Companion animal exposures to potentially poisonous substances reported to a national poison control center in the United States in 2005 through 2014

Alexandra L. Swirski Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.

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David L. Pearl Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.

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Olaf Berke Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.

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Terri L. O'Sullivan Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.

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Abstract

OBJECTIVE

To evaluate data concerning suspected companion animal exposures to possibly hazardous substances reported during telephone calls to the US Animal Poison Control Center (APCC) for characterization of dog and cat exposures to potentially toxic substances in the United States.

SAMPLE

Household-level poisonings events involving dogs and cats in the United States that were reported to the APCC in 2005 through 2014.

PROCEDURES

Substances involved in reported poisonings of dogs and cats were classified into 20 general categories, and descriptive statistical analysis was used to examine the most common categories. Case fatality ratios were estimated for all exposure categories for which a final outcome status of the affected animal was documented.

RESULTS

Over the 10-year study period, 241,261 household-level poisoning events were reported to the APCC from across the United States, of which 86.0% and 14.0% involved dogs and cats, respectively. The most common agent categories reported for dogs included human medicines, foods, and pesticides. The most common agent categories reported for cats included human medicines, plants, and veterinary medicines. Chocolate and Lilium plants were the most commonly reported exposures of dogs and cats, respectively. Fluorouracil (65.2%) and bifenthrin (66.7%) were found to have the highest case fatality ratio for dogs and cats, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

The APCC call data can be used to identify the most common toxicological exposures of dogs and cats, understand the epidemiological aspects of these poisonings, and inform education programs for owners and veterinarians. Data from the APCC may be suitable for surveillance of toxicological exposures of companion animals in the United States.

Abstract

OBJECTIVE

To evaluate data concerning suspected companion animal exposures to possibly hazardous substances reported during telephone calls to the US Animal Poison Control Center (APCC) for characterization of dog and cat exposures to potentially toxic substances in the United States.

SAMPLE

Household-level poisonings events involving dogs and cats in the United States that were reported to the APCC in 2005 through 2014.

PROCEDURES

Substances involved in reported poisonings of dogs and cats were classified into 20 general categories, and descriptive statistical analysis was used to examine the most common categories. Case fatality ratios were estimated for all exposure categories for which a final outcome status of the affected animal was documented.

RESULTS

Over the 10-year study period, 241,261 household-level poisoning events were reported to the APCC from across the United States, of which 86.0% and 14.0% involved dogs and cats, respectively. The most common agent categories reported for dogs included human medicines, foods, and pesticides. The most common agent categories reported for cats included human medicines, plants, and veterinary medicines. Chocolate and Lilium plants were the most commonly reported exposures of dogs and cats, respectively. Fluorouracil (65.2%) and bifenthrin (66.7%) were found to have the highest case fatality ratio for dogs and cats, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

The APCC call data can be used to identify the most common toxicological exposures of dogs and cats, understand the epidemiological aspects of these poisonings, and inform education programs for owners and veterinarians. Data from the APCC may be suitable for surveillance of toxicological exposures of companion animals in the United States.

The curious nature of dogs and cats and their tendency to explore their surroundings makes them highly susceptible to accidental exposure to potentially hazardous substances. Dogs are especially susceptible to accidental ingestion of potentially toxic substances because of their indiscriminate eating habits. Ingestion of pesticides, human and veterinary pharmaceuticals, and plants are the most common exposures implicated in accidental dog and cat poisonings, with most of these exposures occurring in the animals’ home environment.1–10

The home environment poses the greatest toxicological risk for both dogs and cats because of the plethora of toxic products found in and around the animals’ home base.7,9,10 Human activity that results in improper handling and use of these products can increase a pet's risk of exposure to toxins, and accidental contact with a toxin is more likely to occur when the products are not safely stored or when a pet is unsupervised.7,10 Exposure to hazardous substances is also influenced by an owner's knowledge of the toxic potential of substances and the relative abundance of these substances within the home environment.7 Fluctuations in product availability, popularity, and use may alter the relative abundance of hazardous substances in the home environment over time.7 Common household products also undergo reformulation, which may change their potential toxic effects in animals. Such patterns of change with regard to household abundance and toxicity of hazardous substances likely have a substantial impact on the types of pet-related toxic substance exposures encountered by emergency veterinary medical providers. As exposures to potentially toxic substances are one of the most common reasons for emergency visits in companion animal practice,11 it is important to routinely examine trends in toxicological exposures among pets to ensure veterinary care professionals are up to date, well-informed, and, therefore, able to provide the best possible care to their patients.

Currently, there is no central registry for reporting toxicological events in companion animals in the United States. However, there are a number of PCCs that receive calls every day from veterinarians and pet caretakers from across the country who are seeking assistance regarding exposure of animals to potentially toxic substances.1,7,12,13 These PCCs may be an excellent source of data for conducting real-time surveillance of poisoning events in companion animal populations, and such data may provide important insight into emerging trends in companion animal toxicology.

The APCC, operated by the American Society for the Prevention of Cruelty to Animals, is a 24-hour, fee-based, emergency poison control hotline that provides advice regarding toxicological exposures of both wild and domestic animal species. The consultation fee is waived for any case that involves an agent covered by a manufacturer participating in the American Society for the Prevention of Cruelty to Animals’ Animal Product Safety Service program. The APCC receives thousands of telephone calls each year from across Canada and the United States, including US commonwealths and territories, and from a variety of sources (eg, other PCCs, the general public, and veterinarians). The APCC veterinary staff collects extensive data from each telephone call, including the number of animals exposed, exposure history, patient characteristics, clinical signs at the time of the call, diagnostic test results, and outcomes, as well as the source of the report, geographic location of the reporting person who made the first contact with the APCC, and time of the call. These data are subsequently stored in the APCC's animal toxin database. It is important to note that all exposures entered into the animal toxin database are considered to be suspected or possible exposures because the APCC does not collect samples for confirmatory analysis. The objective of the study of the present report was to evaluate data concerning suspected companion animal exposures to possibly hazardous substances reported during telephone calls to the APCC received in 2005 through 2014 for characterization of dog and cat exposures to potentially toxic substances in the United States.

Materials and Methods

SPE data

Information regarding household-level SPEs involving dogs and cats reported to the APCC from within the United States (excluding US commonwealths and territories) in 2005 through 2014 were extracted from the APCC's animal toxin database. Suspected poisoning events associated with the Animal Product Safety Service were excluded from subsequent analyses because it was believed that they would not be representative of regular calls to the hotline and the service fee is waived for these calls. Information concerning exposure, patient characteristics (species, age, weight, sex, and reproductive status), and source of telephone call was available for each SPE. Exposure information included the number of animals exposed, route of exposure, product name and primary ingredient, time of exposure, evidence of exposure, dose, an assessment of the certainty of exposure, and final outcome. Information on the source of the telephone call included the type of caller (veterinarian, other PCC, or member of the general public), time when the APCC received the first telephone call for that particular SPE (the APCC recommends follow-up calls to report findings of laboratory tests and the final outcome of the exposure), and geographic location of the first caller, which included city, state, and zip code. An SPE was defined as a single exposure event in an individual household but may have involved > 1 animal or substance. If someone in a household called and reported a different exposure event at a different point in time, this would be classified as a new SPE. Individual animals involved in the SPEs were identified as patients; each animal may have been exposed to > 1 agent. In short, an SPE could involve > 1 animal, and an animal could be involved in > 1 SPE.

For every SPE, the suspected substance exposure was assigned a certainty measure by the APCC staff on the basis of their assessment of the available data. This measure reflected how certain the APCC staff member who received the telephone call was that the reported findings were attributable to exposure to the agent and involved consideration of the time elapsed since exposure, initial clinical signs, exposure history, and subsequent clinical findings. This measure was assigned at the time of the call. The certainty of exposure was designated as high (ie, the time elapsed since exposure, clinical findings, and history were sufficient and characteristic of agent-related toxicosis), medium (ie, findings were characteristic, but historical or clinical data were not completely available), low (ie, only a few findings were consistent with toxicosis or there were inconsistencies in historical or clinical data), or doubtful (ie, the time elapsed since exposure, findings, and history were not consistent with toxicosis) or was expressed as not related to the suspected exposure (ie, an alternative diagnosis had been made), did not develop (ie, after following up on the case, there was no development of clinical signs), did not monitor (ie, the case was not followed up, and clinical signs were not present at the time of the initial call), or not assessed (ie, a certainty measure was not recorded). The high-, medium-, and low-certainty designations represented probable, suspected, and possible toxic exposures, respectively. The final outcome status of animals affected by an SPE was also classified by the APCC staff member who received sufficient information to assign an outcome status. Final outcomes were classified as death or euthanasia, full recovery, mixed, no development of signs, not asked, development of sequelae, continuation of signs, continuation of treatment, other, or unknown. Suspected poisoning events that were categorized as not asked, development of sequelae, continuation of signs, continuation of treatment, and unknown were not considered as final outcomes for the calculation of CFRs.

Exposure classification

Owing to the large number of exposure agents in the APCC's animal toxin database, agents were classified into 20 general categories on the basis of a modified version of a previously published classification scheme14 (Appendix). Categories of human and veterinary medicines were further subclassified because these agents are commonly involved in small animal poisonings. Subclassification of agents within the human medicine category was performed on the basis of a previously used classification scheme.3 Agents within the veterinary medicine category were subclassified on the basis of a more simplistic classification scheme and were grouped into subcategories of analgesics and pain killers, antimicrobials and antiseptic agents, antiparasitic drugs, drugs to treat CNS disorders, drugs to treat urinary incontinence, topically acting drugs, and vaccines. For both human and veterinary medicines, subclassification included a subgroup of other, which included any agents that had > 1 primary indication.

Descriptive statistical analysis

Descriptive analysis of the characteristics (eg, breed, age, and weight) of dogs and cats involved in SPEs reported to the APCC during the study period was conducted. Categorical variables (eg, species and breed) are reported as proportions. Continuous variables (eg, weight and age) are reported as the mean ± SD if the distribution of data appeared approximately normal on visual assessment of a histogram; if the data distribution was asymmetric, these variables are reported as the median and IQR.

Graphs of the total number of telephone calls to the APCC each month were generated for each species to visually examine any temporal patterns in the reporting of SPEs involving dogs or cats to the APCC. To assess the data on the basis of seasons, the seasons were defined as follows: winter (December through February), spring (March through May), summer (June through August), and fall (September through November). The percentage of SPEs reported to the APCC that were attributable to each route of exposure (eg, oral, dermal and oral, dermal, inhalational, SC, IV, IM, aural, via bite or sting, and other) was also reported by season and species.

To assess the geographic distribution of telephone call sources, the number of calls to the APCC/100,000 residents for each state was calculated by dividing the number of calls to the APCC from each state by the state population. State populations were extracted from the 2010 American Decennial Census.15 These proportions were then assessed visually, for each species, by generating choropleth maps on the basis of 5 categories in a quantile classification scheme (ie, categories with an equal number of observations) with open-source geographic information system software.a

The proportion of SPEs involving each agent category and the top 5 most common exposures for each category (based on the primary ingredient) was reported as a percentage of the total number of SPEs per species. However, some general categories were combined for analysis, and the 10 most common exposures were reported because of the small number of exposures (based on the primary ingredient); these categories included cleaning and maintenance products; fuels, flammable substances, and liquid scents; construction materials; dyes, paints, lacquers, and varnishes; and chemical agents for technical equipment, products, and processes.

Patient-level CFRs were estimated for each species from patient-level SPE data that had a final outcome recorded (eg, the animal died or was euthanized, fully recovered, other, developed sequelae, or developed no clinical signs). Case fatality ratios for each species were calculated as the number of deaths divided by the number of SPEs for agent categories and for individual agents on the basis of the primary ingredient. To avoid inflation of CFRs for agents with few documented exposures, CFRs were calculated only for general agent categories with ≥ 20 recorded exposures and for individual agents with ≥ 10 recorded exposures.

Commercially available statistical softwareb,c was used for all data management, descriptive statistical analyses, and graphical visualizations of data. The 95% CIs for proportions (ie, data reported as percentages) were estimated with the Agresti-Coull method, which provides better estimates than does the standard method.16

Results

Dogs and cats

In 2005 through 2014, a total of 241,253 telephone calls were made to the APCC from pet owners, veterinarians, and other PCCs requesting information regarding household-level SPEs involving dogs and cats. Of those 241,253 calls, 207,492 (86.0%) involved dogs and 33,869 (14.0%) involved cats. The individual number of calls involving dogs or cats added up to more than the total number of calls because 108 (0.04%) calls reported an SPE that involved both a dog and cat from the same household. Exposure of 1 animal/household was reported in 226,777 (94.0%) calls. Overall, these calls represented SPEs involving 253,138 individual dogs and cats.

Of the 217,495 dogs involved in SPEs for which reports were made to the APCC, 104,689 (48.1%) were male and 111,868 (51.4%) were female (Table 1). Of the 35,643 cats involved in SPEs for which reports were made to the APCC, 19,075 (53.5%) were male and 16,179 (45.4%) were female. There were 161,657 (74.3%) neutered dogs and 30,712 (86.2%) neutered cats. The median age of dogs and cats involved in SPEs was 2 years (IQR, 7 months to 5 years) and 3 years (IQR, 1 to 7 years), respectively. The median weight of dogs and cats involved in SPEs was 11.3 kg (24.9 lb; IQR, 5.4 to 26.0 kg [11.9 to 57.2 lb]) and 4.0 kg (8.8 lb; IQR, 2.7 to 5.4 kg [5.9 to 11.9 lb]), respectively.

Table 1—

Distributions of sex and reproductive status among 217,495 dogs and 35,643 cats involved in SPEs reported to the US APCC in 2005 through 2014.

VariableNo. of dogs involved in SPEs (%)No. of cats involved in SPEs (%)
Sex
 Male104,689 (48.13)19,075 (53.52)
 Female111,868 (51.43)16,179 (45.39)
 Unknown938 (0.43)389 (1.09)
   
Reproductive status
  Immature11,518 (5.30)1,090 (3.06)
  Sexually intact35,744 (16.43)2,390 (6.71)
  Lactating234 (0.11)45 (0.13)
  Pregnant157 (0.07)16 (0.04)
  Neutered161,657 (74.33)30,712 (86.17)
  Unknown8,185 (3.76)1,390 (3.90)

Among the 217,495 dogs involved in SPEs, the most common breeds were Labrador Retrievers (29,144 [13.4%]), Chihuahuas (10,439 [4.8%]), Yorkshire Terriers (8,917 [4.1%]), Golden Retrievers (8,917 [4.1%]), and Boxers (7,177 [3.3%]). Among the 35,643 cats involved in SPEs, the most common breeds were domestic shorthair (25,057 [70.3%]), domestic longhair (3,136 [8.8%]), domestic medium hair (2,138 [6.0%]), Siamese (1,104 [3.1%]), and Maine Coon (321 [0.9%]).

Temporal distribution of calls to the APCC

Although the APCC typically receives telephone calls relatively steadily throughout any given year, there was an evident seasonal pattern in call volume, regardless of species, during the study period. In general, call volume began to increase in March, peaked in June and July, and then decreased slightly followed by a smaller secondary peak in October (Figure 1). The call volume then decreased over the winter months and reached its lowest level in February. Regarding dogs and cats involved in SPEs, the month with the highest volume of calls was December and July, respectively. The lowest volume of calls occurred in February for calls involving exposures of either species.

Figure 1—
Figure 1—

Monthly distribution of telephone calls from pet owners, veterinarians, and other PCCs requesting information regarding household-level SPEs involving dogs (dark gray bars) and cats (light gray bars) received by the US APCC in 2005 through 2014. In the 10-year period, the number of telephone calls concerning SPEs received was 241,253, of which 207,492 (86.0%) involved dogs and 33,869 (14.0%) involved cats; 108 (0.04%) calls involved both a dog and a cat from the same household.

Citation: Journal of the American Veterinary Medical Association 257, 5; 10.2460/javma.257.5.517

Geographic distribution of calls to the APCC

Suspected poisoning events were reported from all US states throughout the study period, and the geographic distribution of telephone calls was similar between species (Figure 2). The greatest proportion of calls received by the APCC for SPEs involving dogs or cats came from the states in the northeast region (eg, Maine, New Hampshire, Pennsylvania, Virginia, and New Jersey) and the lowest proportions of calls came from states located in the Midwest (eg, Montana, North Dakota, Wyoming, South Dakota, and Nebraska) and the southeast regions (eg, Louisiana, Oklahoma, Arkansas, Mississippi, and Alabama).

Figure 2—
Figure 2—

Volume of telephone calls (No. of telephone calls/100,000 residents) concerning SPEs involving dogs (A) and cats (B) received by the US APCC in 2005 through 2014, displayed by state.

Citation: Journal of the American Veterinary Medical Association 257, 5; 10.2460/javma.257.5.517

Common exposures

Exposure to only 1 agent was reported for 176,392 of the 207,492 (85.0%) SPEs involving dogs and for 29,710 of the 33,869 (87.7%) SPEs involving cats. Among the 241,253 SPEs overall, exposure to 2 agents was reported for 24,125 (10%) SPEs and ≥ 3 exposures were reported for 12,063 (5.0%) SPEs. Given that some animals were exposed to > 1 product, the number of reported toxicants in SPEs involving dogs and cats were 271,678 and 42,062, respectively.

For the SPEs reported to the APCC during the study period, suspected substance exposures were each assigned a certainty measure by the APCC staff on the basis of their assessment of the available data. A high or medium degree of certainty regarding the clinical syndrome associated with the suspected exposure was assigned to 172,678 of 271,678 (63.6%) reported toxicants in SPEs involving dogs and 25,405 of 42,062 (60.4%) reported toxicants in SPEs involving cats (Table 2). Exposures most commonly occurred via the oral or dermal route, or a combination of both, for both species (Table 3). However, there were noticeable differences in the percentages of exposures by each route across seasons and species. In particular, strictly oral exposure was more common for dogs than it was for cats and dermal and oral or strictly dermal exposure was more common for cats than they were for dogs.

Table 2—

Distribution of the assigned measure of certainty for and species involved in SPEs reported to the US APCC in 2005 through 2014.

Measure of certaintyPercentage of dog exposures (95% CI)Percentage of cat exposures (95% CI)
High38.46 (38.28–38.64)36.12 (35.66–36.58)
Medium25.13 (25.00–25.30)24.32 (23.92–24.74)
Low15.18 (15.05–15.32)16.10 (15.75–16.45)
Doubtful11.63 (11.51–11.75)13.91 (13.58–14.24)
Not related5.63 (5.55–5.72)5.71 (5.49–5.94)
Did not develop0.20 (0.18–0.22)0.20 (0.16–0.25)
Did not monitor1.53 (1.49–1.58)0.92 (0.83–1.02)
Not assessed0.34 (0.32–0.37)0.47 (0.41–0.54)
Unknown1.89 (1.84–1.94)2.25 (2.11–2.39)

*Reported exposures included potential exposures to unique products; therefore, there are more exposures than the number of animals because some animals were exposed to > 1 product (ie, 271,443 exposures involving 217,495 dogs and 42,062 exposures involving 35,643 cats).

Table 3—

Seasonal distribution of SPEs involving dogs and cats that were associated with various routes of exposure and were reported to the US APCC in 2005 through 2014.

DogsCats
Route of exposureWinter (95% CI)Spring (95% CI)Summer (95% CI)Fall (95% CI)Winter (95% CI)Spring (95% CI)Summer (95% CI)Fall (95% CI)
Oral only95.33 (95.14–95.51)92.65 (92.43–92.87)90.96 (90.72–91.20)93.04 (92.82–93.26)77.63 (76.65–78.58)76.39 (75.49–77.26)67.85 (66.91–68.78)68.59 (67.58–69.58)
Dermal and oral1.99 (1.87–2.12)3.08 (2.94–3.23)3.75 (3.59–3.92)2.67 (2.53–2.81)12.05 (11.31–12.82)12.08 (11.42–12.78)14.30 (13.61–15.02)14.05 (13.32–14.52)
Dermal only1.07 (0.98–1.17)2.11 (1.99–2.24)2.70 (2.57–2.84)2.26 (2.13–2.39)5.72 (5.20–6.28)6.81 (6.31–7.36)12.19 (11.55–12.86)12.07 (11.39–12.79)
Inhalational0.35 (0.30–0.40)0.38 (0.33–0.43)0.46 (0.41–0.53)0.36 (0.31–0.41)0.78 (0.60–1.01)0.55 (0.42–0.73)1.07 (0.88–1.30)0.90 (0.72–1.13)
SC0.16 (0.13–0.20)0.21 (0.17–0.25)0.20 (0.17–0.24)0.19 (0.15–0.23)0.70 (0.53–0.92)0.53 (0.40–0.71)0.60 (0.46–0.78)0.64 (0.49–0.83)
IV0.20 (0.17–0.25)0.24 (0.20–0.29)0.22 (0.19–0.27)0.25 (0.21–0.30)0.53 (0.38–0.73)0.44 (0.32–0.60)0.50 (0.38–0.67)0.60 (0.45–0.79)
IM0.08 (0.05–0.10)0.10 (0.07–0.12)0.10 (0.07–0.12)0.08 (0.06–0.11)0.32 (0.21–0.48)0.30 (0.21–0.44)0.18 (0.11–0.29)0.28 (0.18–0.42)
Aural0.05 (0.03–0.07)0.07 (0.05–0.09)0.05 (0.04–0.08)0.09 (0.06–0.11)0.25 (0.16–0.40)0.20 (0.13–0.32)0.19 (0.12–0.30)0.23 (0.14–0.36)
Via bite or sting0.01 (0.01–0.03)0.08 (0.06–0.10)0.15 (0.12–0.18)0.07 (0.05–0.10)0.04 (0.08–0.13)0.07 (0.03–0.15)0.07 (0.32–0.16)0.06 (0.02–0.15)
Other*1.45 (1.35–1.56)2.01 (1.89–2.14)2.40 (2.27–2.53)1.89 (1.78–2.01)3.39 (2.99–3.83)3.84 (3.45–4.26)5.16 (4.73–5.62)4.38 (3.96–4.84)

Data are reported as the percentage of SPEs associated with each route of exposure for each season and species.

This category includes intraperitoneal, not asked, ocular, rectal, vaginal, by other route (no other information was available for route of exposure), and unknown routes of exposure.

Seasons were defined as follows: winter (December through February), spring (March through May), summer (June through August), and fall (September through November).

The suspected substance exposure for each SPE was assigned a certainty measure by the APCC staff on the basis of their assessment of the available data. The certainty of exposure was designated as high certain (ie, the time elapsed since exposure, clinical findings, and history are sufficient and characteristic of agent-related toxicosis), medium (ie, findings are characteristic, but historical or clinical data are not completely available), low (ie, only a few findings are consistent with toxicosis or there are inconsistencies in historical or clinical data), doubtful (ie, the time elapsed since exposure, findings, and history are not consistent), not related to the suspected exposure (ie, an alternative diagnosis has been made), did not develop (ie, after following up the case, there is no development of clinical signs), did not monitor (ie, the case was not followed up and clinical signs were not present at the time of the initial call), or not assessed (ie, a certainty measure was not recorded). The high-, medium-, and low-certainty designations represented probable, suspected, and possible toxic exposures, respectively.

Seasonal variations in the relative proportion of SPEs that occurred via the oral, dermal and oral, dermal, inhalational, and bite or sting exposure routes were evident (Table 3). In particular, the percentages of dermal and dermal and oral exposures for both species were the lowest in the winter and highest in the summer. Among dogs, the percentage of SPEs that occurred via bites and stings was greater in the summer than in the winter. Among cats, the percentage of SPEs that involved inhalational exposures was greater in the summer than in the spring or winter. However, those seasonal variations for either species were not examined statistically.

The most common categories of agents and subgroups of drugs involved in SPEs reported to the APCC during the study period were similar for dogs and cats, with a few noticeable differences (Tables 4 and 5). Dogs were most commonly exposed to human medicines; food intended for human consumption; pesticides, fertilizers, and plant protection agents; plants and wild mushrooms; and human and veterinary dietary supplements (nonprescription). Conversely, cats were most commonly exposed to human medicines; plants and wild mushrooms; veterinary medicines; pesticides, fertilizers, and plant protection agents; and cleaning and maintenance products. The top 5 most commonly reported specific agents in SPEs involving dogs (in descending order) were chocolate, ibuprofen, sucrose-containing foods, nitrogen-based fertilizers, and acetaminophen (Tables 68). The top 5 most commonly reported specific agents in SPEs involving cats (in descending order) were Lilium spp, canine spot-on permethrin treatments, glow sticks or jewelry (ie, dibutyl phthalate), ibuprofen, and Dracaena plants.

Table 4—

Agent exposures (by category) in SPEs involving dogs and cats as a percentage of the total number of SPEs for each species that were reported to the US APCC in 2005 through 2014.

Agent categoryPercentage of SPEs involving dogs* (95% CI)Percentage of SPEs involving cats* (95% CI)
Biocides1.03 (0.98–1.07)2.41 (2.25–2.58)
Bites and stings0.09 (0.08–0.10)0.06 (0.04–0.10)
Chemical agents for technical equipment, products, and processes0.55 (0.52–0.58)0.17 (0.13–0.21)
Cleaning and maintenance products5.04 (4.95–5.14)8.33 (8.04–8.63)
Construction materials1.74 (1.68–1.80)1.93 (1.79–2.08)
Consumer items and products2.25 (2.19–2.13)3.61 (3.42–3.82)
Cosmetics and personal care products3.82 (3.74–3.90)2.70 (2.53–2.88)
Dyes, paints, lacquers, and varnishes0.85 (0.82–0.90)1.46 (1.13–1.60)
Food intended for human consumption19.47 (19.30–19.64)2.00 (1.89–2.15)
Foreign bodies0.30 (0.28–0.33)0.17 (0.13–0.22)
Fuels, flammable substances, and liquid scents1.93 (1.84–1.99)2.41 (2.25–2.58)
Human or veterinary dietary supplements9.60 (9.47–9.73)3.53 (3.33–3.73)
Human medicines40.82 (40.60–41.03)32.74 (32.24–33.24)
Other or unknown2.30 (2.24–2.37)1.53 (1.40–1.66)
Pesticides, fertilizers, or plant protection agents15.67 (15.51–15.82)10.33 (10.01–10.66)
Pet products, foods, or treats0.49 (0.46–0.52)0.31 (0.26–0.38)
Plants or wild mushrooms9.68 (9.54–9.80)28.27 (27.80–28.76)
Tobacco or recreational or illicit drugs1.83 (1.77–1.89)0.44 (0.37–0.51)
Unclassified medicines0.42 (0.40–0.45)0.48 (0.41–0.56)
Veterinary medicines6.96 (6.86–7.07)15.27 (14.90–15.66)

Given that animals could have been exposed to > 1 agent or class of agent, the sum of the percentages for each species exceeded 100%.

Table 5—

Human and veterinary pharmaceutical exposures in SPEs involving dogs and cats as a percentage of the total number of SPEs for each species that were reported to the US APCC in 2005 through 2014.

Pharmaceutical categoryPercentage of SPEs involving dogs (95% CI)Percentage of SPEs involving cats (95% CI)
Human pharmaceuticals  
  Analgesics and pain killers10.11 (9.99–11.02)6.08 (5.83–6.34)
  Antihistamines1.59 (1.53–1.64)1.13 (1.02–1.25)
  Antimicrobials, antiseptics, and vaccines1.08 (1.04–1.12)0.88 (0.79–0.99)
  Antineoplastic drugs0.35 (0.32–0.38)0.05 (0.03–0.08)
  Birth control products and contraceptives0.25 (0.23–0.27)0.04 (0.02–0.07)
  Cardiovascular drugs4.06 (3.98–4.15)2.87 (2.70–3.05)
  Drugs administered aurally, ocularly, or nasally0.98 (0.94–1.02)0.29 (0.24–0.36)
  Drugs to treat CNS disorders13.55 (13.41–13.70)15.92 (15.53–16.31)
  Drugs to treat endocrine disorders1.52 (1.46–1.57)1.09 (0.98–1.21)
  Drugs to treat gastrointestinal disorders2.07 (2.00–2.13)2.18 (2.03–2.34)
  Drugs to treat musculoskeletal disorders1.62 (1.57–1.68)0.87 (0.78–0.98)
  Drugs to treat respiratory tract disorders1.92 (1.87–1.98)0.21 (0.17–0.27)
  Immunosuppressant drugs0.38 (0.35–0.41)0.14 (0.11–0.19)
  Other0.51 (0.48–0.54)0.42 (0.36–0.50)
  Prescription nutritional supplements0.15 (0.14–0.17)0.20 (0.16–0.25)
  Topically acting drugs0.67 (0.64–0.71)0.23 (0.18–0.28)
Veterinary pharmaceuticals  
  Analgesics and pain killers1.34 (1.29–1.39)0.83 (0.74–0.93)
  Antimicrobials and antiseptics0.36 (0.34–0.39)0.68 (0.60–0.77)
  Antiparasitic drugs3.70 (3.62–3.78)12.89 (12.54–13.25)
  Drugs to treat CNS disorders0.26 (0.24–0.28)0.35 (0.30–0.42)
  Drugs to treat urinary incontinence0.79 (0.75–0.82)0.05 (0.03–0.09)
  Other0.38 (0.35–0.40)0.33 (0.28–0.40)
  Topically acting drugs0.07 (0.06–0.09)0.06 (0.04–0.09)
  Vaccines0.06 (0.05–0.07)0.07 (0.05–0.10)
Table 6—

Top 5 most common drug exposures (based on primary ingredient) associated with human medicines, tobacco and recreational or illicit drugs, human and veterinary dietary supplements, and veterinary medicines in SPEs involving dogs and cats as a percentage of the total number of SPEs for each species reported to the US APCC in 2005 through 2014.

 DogsCats
Agent categoryPrimary ingredientPercentage of SPEs involving dogs (95% CI)Primary ingredientPercentage of SPEs involving cats (95% CI)
Human medicinesIbuprofen3.42 (3.34–3.50)Ibuprofen1.56 (1.44–1.70)
 Acetaminophen1.48 (1.43–1.53)Amphetamine aspartate1.37 (1.25–1.50)
 Amphetamine aspartate1.06 (1.02–1.10)Venlafaxine hydrochloride1.34 (1.22–1.47)
 Alprazolam1.02 (0.98–1.06)Acetaminophen1.30 (1.19–1.43)
 Clonazepam0.89 (0.85–0.93)Pregabalin0.94 (0.84–1.05)
     
Tobacco and recreational or illicit drugsCannabis (including synthetic derivatives)0.99 (0.95–1.04)Cannabis (including synthetic derivatives)0.14 (0.11–0.19)
 Tobacco (cigarettes)0.58 (0.55–0.61)Tobacco (cigarettes)0.14 (0.10–0.18)
 Methamphetamine0.10 (0.09–0.93)Methamphetamine0.07 (0.05–0.11)
 Cocaine0.05 (0.05–0.07)Cocaine0.04 (0.02–0.07)
 Heroin hydrochloride0.01 (0.01–0.06)Diacetylmorphine0.12 (0.03–0.32)
     
Human and veterinary dietary supplementsMultivitamin or prenatal vitamin1.23 (1.18–1.27)Vitamin D0.32 (0.29–0.41)
 Vitamin D0.88 (0.84–0.92)Multivitamin or prenatal vitamin0.28 (0.23–0.34)
 Ascorbic acid0.47 (0.44–0.50)Minoxidil0.15 (0.11–0.20)
 Fish oil0.31 (0.28–0.33)Methionine0.15 (0.11–0.20)
 5-hydroxytryptophan0.90 (0.86–0.94)Ascorbic acid0.13 (0.10–0.18)
     
Veterinary medicinesCarprofen0.76 (0.73–0.80)Permethrin3.56 (3.37–3.77)
 Cyphenothrin0.70 (0.67–0.74)S-methoprene0.94 (0.84–1.05)
 Ivermectin0.66 (0.63–0.70)Etofenprox0.94 (0.84–1.05)
 Phenylpropanolamine hydrochloride0.66 (0.63–0.70)Imidacloprid0.93 (0.84–1.04)
 Spinosad0.56 (0.62–0.59)Fipronil0.82 (0.73–0.93)
Table 7—

Top 5 most common food and household exposures (based on primary ingredient) associated with food intended for human consumption, consumer products, cosmetics and personal care products, and a group of various cleaning and maintenance products, chemicals, construction materials, fuels, scents, and paints in SPEs involving dogs and cats as a percentage of the total number of SPEs for each species reported to the US APCC in 2005 through 2014.

 DogsCats
Agent categoryPrimary ingredientPercentage of SPEs involving dogs (95% CI)Primary ingredientPercentage of SPEs involving cats (95% CI)
Food intended for human consumptionChocolate7.40 (7.29–7.51)Onion and garlic0.38 (0.32–0.45)
 Sucrose*2.05 (1.99–2.11)Chocolate0.30 (0.25–0.37)
 Sorbitol*1.38 (1.33–1.43)Raisins and grapes0.13 (0.10–0.18)
 Xylitol*1.03 (0.99–1.07)Avocado0.10 (0.01–0.14)
 Raisins and grapes0.93 (0.89–0.98)Sucrose*0.10 (0.01–0.14)
     
Consumer productsPolyethylene glycol0.27 (0.25–0.29)Glow stick or jewelry (dibutyl phthalate)2.74 (2.57–2.92)
 Silica gel0.21 (0.19–0.24)Potpourri (nonliquid)0.51 (0.44–0.60)
 Potpourri (nonliquid)0.18 (0.16–0.20)Silica gel0.18 (0.14–0.23)
 Elemental iron0.15 (0.14–0.17)Calcium chloride0.12 (0.08–0.16)
 Sodium polyacrylate0.14 (0.14–0.16)Sodium polyacrylate0.03 (0.02–0.06)
     
Cosmetic or personal care productsZinc oxide0.97 (0.93–1.01)Tea tree oil0.45 (0.38–0.53)
 Tea tree oil0.28 (0.26–0.31)Aloe vera0.13 (0.10–0.18)
 Petrolatum0.19 (0.17–0.21)Essential oils (nonspecific)0.10 (0.07–0.14)
 Sodium cocoyl isethionate0.15 (0.14–0.17)Acetone0.07 (0.05–0.11)
 Elemental iron0.15 (0.13–0.16)Eucalyptus0.07 (0.07–0.10)
     
Cleaning or maintenance products, chemicals, construction materials, fuels, liquid scents, or paintsEthylene glycol0.51 (0.48–0.55)Ethylene glycol0.78 (0.69–0.88)
 Sodium hypochlorite0.42 (0.39–0.44)Sodium hypochlorite0.71 (0.63–0.81)
 Petroleum distillate (nonspecific)0.29 (0.27–0.32)Sodium hydroxide0.55 (0.47–0.63)
 Sodium chloride0.26 (0.24–0.28)Liquid potpourri0.48 (0.41–0.57)
 Potassium hydroxide0.24 (0.22–0.27)Anionic surfactants0.33 (0.27–0.39)

Group includes products that contained this sweetener as the primary ingredient, and not products that contained chocolate as the primary ingredient.

Owing to a small number of exposures (based on primary ingredient), several agent categories (cleaning and maintenance products; construction materials; chemical agents for technical processes, equipment, products, and processes; fuels, flammable substances, and liquid scents; and dyes, paints, lacquers, and varnishes) were combined to examine the top 10 primary ingredients.

Table 8—

Top 5 most common plant and outdoor exposures (based on primary ingredient) associated with plants and wild mushrooms; pesticides, fertilizers, and plant protection agents; and biocides in SPEs involving dogs and cats as a percentage of the total number of SPEs for each species reported to the US APCC in 2005 through 2014.

 DogsCats
Agent categoryPrimary ingredientPercentage of SPEs involving dogs (95% CI)Primary ingredientPercentage of SPEs involving cats (95% CI)
PlantsMushrooms0.97 (0.93–1.02)Lilium spp5.86 (5.61–6.11)
 Cyca spp0.43 (0.40–0.46)Dracaena spp1.47 (1.35–1.61)
 Hydrangea spp0.29 (0.27–0.32)Spathiphyllum spp1.16 (1.05–1.28)
 Spathiphyllum spp0.24 (0.22–0.27)Zantedeschia spp0.83 (0.74–0.93)
 Vitis spp0.24 (0.22–0.26)Alstroemeria spp0.73 (0.64–0.82)
     
Pesticides, fertilizers, and plant protection agentsNitrogen-based fertilizers2.00 (1.94–2.06)Permethrin0.70 (0.62–0.79)
 Cyhalothrin1.13 (1.08–1.17)Bifenthrin0.61 (0.62–0.79)
 Bifenthrin0.79 (0.75–0.83)Nitrogen-based fertilizers0.59 (0.51–0.67)
 Brodifacoum   
 Bromethalin0.64 (0.60–0.67)Brodifacoum0.40 (0.34–0.48)
     
BiocidesAlkyl dimethylbenzylammonium chloride0.16 (0.15–0.18)Alkyl dimethylbenzylammonium chloride0.64 (0.56–0.73)
 Calcium hypochloride0.09 (0.08–0.10)Dodecyl dimethyl ammonium chloride0.33 (0.27–0.40)
 Trichloroisocanuric acid0.08 (0.07–0.10)Benzyl-C12–18-alkyldimethyl quaternary ammonium chloride0.22 (0.18–0.28)
 Sodium dichloroisocyanurate dehydrate0.08 (0.07–0.09)Benzalkonium chloride0.14 (0.11–0.19)
 Benzyl-C12–18-akyldimethyl quaternary ammonium chloride0.07 (0.06–0.08)Sodium dichloroisocyanurate dehydrate0.12 (0.09–0.16)

Exposures involving veterinary and human pharmaceuticals

Suspected exposures to veterinary and human medicines, prescription nutritional supplements, and recreational or illicit drugs were reported for 123,635 of 207,472 (59.6%) SPEs involving dogs and 17,690 of 33,761 (52.4%) SPEs involving cats (Tables 4 and 5). For dogs, exposures to human pharmaceuticals, recreational drugs, and prescription nutritional supplements represented a greater proportion of SPEs, compared with findings for cats. Conversely, products intended for veterinary use were more commonly associated with exposures of cats than with exposures of dogs.

The most commonly reported specific drug exposures for SPEs involving dogs were ibuprofen, acetaminophen, multi- or prenatal vitamins, amphetamine aspartate, alprazolam, and cannabis (including synthetic derivatives; Table 6). Among the SPEs involving dogs, 2,075 of 207,472 (1.0%) involved a suspected exposure to cannabis and synthetic derivatives (eg, tetrahydrocannabinol [THC] and 1-naphthalenyl(1-pentyl-1H-indol-3-yl)-methanone [JWH 018]). Exposures to these substances tripled in number from the beginning (102 cases in 2005) to the end of the study period (369 cases in 2014). Furthermore, exposures to synthetic cannabinoids (excluding THC) were not reported until 2010, and the number of exposures to synthetic cannabinoids increased from 3 cases in 2010 to 31 cases in 2014. The most commonly reported specific drug exposures for SPEs involving cats were permethrin, ibuprofen, amphetamine aspartate, venlafaxine hydrochloride, and acetaminophen.

Exposures involving food and household products

During the study period, 74,690 of 207,472 (36.0%) SPEs involving dogs and 7,664 of 33,761 (22.7%) SPEs involving cats were attributable to cleaning and maintenance products, chemical agents for technical processes, construction materials, consumer items and products, and cosmetics and personal care products (Table 4). For dogs and cats, the greatest proportion of household product exposures reported as SPEs involved foods intended for human consumption and household chemicals, respectively.

The most common specific foods and household products reported as SPEs involving dogs included chocolate; foods containing sucrose, sorbitol, or xylitol as the main ingredient (and did not contain chocolate as the main ingredient); and cosmetics containing zinc oxide as the primary ingredient (Table 7). Conversely, the most common specific foods and household products reported as SPEs involving cats were glow sticks or jewelry (ie, dibutyl phthalate), ethylene glycol, sodium hypochlorite, liquid potpourri, onions and garlic, and cosmetics containing tea tree (Melaleuca alternifolia) oil.

Exposures involving plant and outdoor toxins

During the study period, outdoor toxins (eg, plants; pesticides, fertilizers, and plant-protection agents; or biocides) were reported for 54,773 of 207,472 (26.4%) SPEs involving dogs and 13,842 of 33,761 (41.0%) SPEs involving cats. The most common exposure of dogs was to pesticides, whereas the most common exposure of cats was to plants.

For dogs, the most commonly reported specific exposures were nitrogen-based fertilizers, cyhalothrin, mushrooms, bifenthrin, and brodifacoum (Table 8). Conversely, for cats, the most commonly reported specific exposures were various species of plants (ie, in decreasing order: Lilium spp, Dracaena spp, Spathiphyllum spp, Zantedeschia spp, and Alstroemeria spp).

Exposure outcomes

With regard to the SPEs reported during the study period, a final outcome (eg, death or euthanasia, full recovery, mixed, no development of signs, not asked, development of sequelae, continuation of signs, continuation of treatment, other, or unknown) was reported for 13,862 of the 271,443 (5.1%) dogs and 2,561 of the 42,062 (6.1%) cats involved. Among the animals for which a final outcome was reported, 2,617 of the 13,863 (18.9%) dogs and 686 of the 2,561 (26.8%) cats died or were euthanized.

On the basis of patient-level exposures with documented final outcomes, the highest proportions of fatal exposures in SPEs involving dogs were associated with pet products and foods, biocides, and foreign bodies (Table 9). The highest proportions of fatal exposures in SPEs involving cats were associated with pesticides, unclassified medicines, and cleaning and maintenance products. The primary ingredients responsible for the highest CFRs among dogs were fluorouracil, thioctic acid, phenylbutazone, and ethylene dichloride (Table 10). The primary ingredients with the highest CFRs among cats were bifenthrin, borax, metronidazole, nitrogen, bromethalin, and methimazole.

Table 9—

Case fatality ratios (based on the number of exposures per category*), by species, for agent categories in SPEs involving dogs and cats with recorded outcomes that were reported to the US APCC in 2005 through 2014.

 DogsCats
Agent categoryNo. of deathsNo. of exposuresCFR (95% CI)No. of deathsNo. of exposuresCFR (95% CI)
Biocides349336.56 (24.47–46.71)93129.03 (15.94– 46.45)
Bites and stings412NA01NA
Chemical agents for technical equipment, products, and processes52420.83 (8.80–40.91)02NA
Cleaning and maintenance products12541030.49 (26.23–35.11)5913743.07 (35.07–51.44)
Construction materials3115220.39 (14.72–27.53)144134.15 (21.50–49.51)
Consumer items and products2420111.94 (8.10–17.20)52817.85 (7.41–36.06)
Cosmetics and personal care products352392.93 (1.19–5.94)124427.27 (16.23–41.99)
Dyes, paints, lacquers, and varnishes107014.29 (7.07–24.71)42119.05 (7.08–40.59)
Food intended for human consumption2071,47514.03 (12.35–15.90)32412.50 (3.50–31.84)
Foreign bodies102835.71 (20.63–54.25)12NA
Fuels, flammable substances, and liquid scents2312718.11 (12.32–25.77)113828.95 (16.88–44.88)
Human and veterinary dietary supplements1921,19216.11 (14.13–18.31)3412527.20 (20.14–35.62)
Human medicines8595,35616.04 (15.08–17.05)19188121.68 (19.08–24.52)
Other or unknown8231126.37 (21.77–31.54)92142.86 (24.44–63.48)
Pesticides, fertilizers, and plant protection agents4561,63915.37 (13.71–17.20)8516950.53 (42.84–57.74)
Pet products, foods, and treats349137.36 (28.11–47.64)1016NA
Plants and wild mushrooms2521,10522.81 (20.43–25.37)9740424.01 (20.09–28.41)
Tobacco and recreational or illicit drugs141837.65 (4.52–12.52)313NA
Unclassified medicines197225.39 (17.52–38.64)112544.00 (26.65–62.95)
Veterinary medicines2011,08218.56 (16.37–21.00)12853823.79 (20.38–27.57)

Patient-level CFRs were estimated for each species from SPE data that had a final outcome recorded (eg, the animal died or was euthanized, fully recovered, other, developed sequelae, or developed no clinical signs). Case fatality ratios were calculated for only agent categories with ≥ 20 recorded exposures. NA = Agent category for which a CFR was not calculated because there were < 20 recorded exposures.

Table 10—

Case fatality ratios (based on the number of exposures to primary ingredient*), by species, for the top 20 most fatal exposures in SPEs involving dogs and cats with recorded outcomes that were reported to the US APCC in 2005 through 2014.

DogsCats
Primary ingredientNo. of deathsNo. of exposuresCFR (95% CI)Primary ingredientNo. of deathsNo. of exposuresCFR (95% CI)
Fluorouracil10716465.24 (57.67–72.12)Bifenthrin8126.67 (38.10–86.45)
Thioctic acid71163.64 (35.19–85.02)Borax61060.00 (3.16–83.29)
Phenylbutazone81656.25 (33.15–76.93)Metronidazole61060.00 (3.16–83.29)
Ethylene dichloride61154.54 (28.00–78.75)Nitrogen61154.54 (27.99–78.75)
Amlodipine92142.86 (24.44–63.48)Bromethalin61154.54 (27.99–78.75)
Blue-green algae61442.86 (24.44–63.48)Methimazole51050.00 (23.66–76.34)
Hydroxyurea51241.67 (19.26–68.11)Minoxidil81747.06 (26.16–69.04)
Didecyl dimethyl ammonium chloride71741.18 (21.56–64.05)DEET61346.15 (23.19–70.87)
Hydrogen peroxide82040.00 (16.71–68.84)Ethylene glycol92045.00(25.81–65.81)
Stoddard solvent41040.00 (16.71–68.84)S-methoprene163941.03 (27.06–56.60)
Mirtazapine41040.00 (16.71–68.84)Sulfurated lime solution41040.00 (16.71–68.84)
Ethylene glycol389739.18 (30.04–49.13)Selamectin71838.89 (20.23–61.46)
Calcitriol82138.10 (20.65–59.20)Dracaena spp61735.29 (17.17–58.84)
Green tea–based weight-loss product82138.10 (20.65–59.20)Meloxicam61735.29 (17.17–58.84)
Methomyl61637.50 (18.37–61.47)Pyrethrin (nonspecific)93030.00 (15.52–48.02)
Lamotrigine267037.14 (26.75–48.87)Acetaminophen155427.78 (17.53–40.98)
Bromethalin4211536.52 (28.28–45.64)Multivitamin41526.67 (10.46–52.38)
Caffeine3711033.63 (25.47–42.90)Enrofloxacin51926.32 (11.45–49.15)
Aldicarb123633.33 (20.14–49.74)Tramadol hydrochloride31225.00 (8.27–53.85)
Colchicine72233.33 (20.14–49.74)Mirtazapine104124.39 (13.65–39.51)

Patient-level CFRs were estimated for each species from SPE data that had a final outcome recorded (eg, the animal died or was euthanized, fully recovered, other, developed sequelae, or developed no clinical signs). Case fatality ratios were calculated for only individual agents with ≥ 10 recorded exposures.

DEET = N, N-Diethyl-meta-toluamide.

Discussion

Disease surveillance within companion animal populations is beneficial for many reasons, and the data can be used to direct veterinary teaching curricula, inform veterinary practitioners, and detect disease trends in both human and animal populations.17 For example, the 2007 melamine pet food contamination incident exemplified the devastating impact a point-source foodborne outbreak can have on the North American companion animal population. This outbreak also emphasized the impact these exposures can have on human public health because food items intended for human consumption were also found to be contaminated with melamine.18 This event highlighted the need for enhanced reporting of exposures of animals to toxic substances and subsequent development of a real-time surveillance system that could provide data to guide veterinary and human public health action during future large-scale exposure events. Currently, there is no central registry for the reporting of toxicological events involving companion animals in the United States12,19; nevertheless, PCCs such as the APCC may be able to perform real-time surveillance of poisoning events. However, there are a number of important factors to consider before application of APCC data for this purpose, including examining the reports made to the APCC to determine their geographic distribution and representativeness across the US companion animal population and identifying recurring trends in exposure reporting, as well as other factors that may bias reporting to the APCC. As such, the present study represented a first step in assessing the suitability of APPC SPE–related call data for the purposes of real-time surveillance of poisoning events. However, the results from this study have suggested that there are factors, such as season, geographic location, animal breed, and presumably owner SES, that may influence submission of reports to the APCC, and further analyses are warranted prior to use of such data for surveillance purposes.

Assessment of the APCC's telephone call volume in 2005 through 2014 revealed a seasonal trend with peak volumes occurring over the summer months, regardless of whether dogs or cats were involved in the reported SPEs. The diversity of reported routes of exposures also increased for both species during the summer and fall months. This likely reflected an increase in the amount of time pets spent outdoors during warmer months and greater variety of and accessibility to potentially harmful substances in the environment, such as pesticides, plants, and poisonous or venomous animals.6,7,9 There was also a substantial peak in call volume in December regarding SPEs involving dogs. This may be explained by an increase in the presence and abundance of chocolate in homes because of seasonal holidays. Identification of these patterns among SPEs may be helpful for targeting educational programming to prevent possible exposures of dogs and cats to toxic substances. These results also suggested that correction for seasonal trends should be made prior to the use of temporal or spatial-temporal quantitative methods for disease surveillance to avoid bias among acquired data.

Although the APCC receives telephone calls from across the United States each year, call volume per state was found to be highly variable and did not reflect the size of the companion animal population in a given state. Many of the states with the highest call volume had the lowest proportions of pet-owning families in the country.20 It was likely that the geographic distribution of calls was influenced by socioeconomic factors, and the states with large urban centers and high overall SES contributed the most to call volume during the study period. Moreover, it has been previously noted that pet owners with lower household incomes are less likely to use veterinary services.21 Hence, the APCC consult fee may be cost prohibitive for some individuals, and the influence of SES on report submission to the APCC warrants further investigation.

There were notable differences between SPEs involving dogs and cats regarding call volume and the types, routes, and times of exposures. These differences between species were likely not a function of companion animal population size because it is estimated that there are approximately 10 million more pet cats than pet dogs in the United States.20 Instead, these differences were likely attributable to differences in behavioral and physiologic factors between the 2 species and to differences in the pet health care–seeking behaviors of their owners. Dogs are omnivores, have indiscriminate eating habits, and tend to investigate the environment with their mouths. Conversely, cats are discriminate eaters and tend to refuse material that they do not associate with food.21,22 These differences likely affect the numbers and types of substances to which dogs or cats are exposed. Dogs are also likely to ingest a greater amount of a substance because they tend to gulp their food, whereas cats tend to chew their food. However, cats are more likely than dogs to be exposed through a combined dermal-oral route because of their grooming behaviors.23 Ultimately, these differences in eating habits and the facts that dogs are more likely to display sickness behaviors than are cats and that dog owners are more likely to seek veterinary-related help would probably result in a greater proportion of exposures of dogs to toxicants being reported to the APCC.21,22 However, it is likely that a greater proportion of cat-related calls involved more severe outcomes because cats are true carnivores and have fewer biotransformation enzymes that lead to delayed toxin clearance and increased risk for serious health outcomes. Furthermore, cats have highly concentrated urine, which can potentially put them at higher risk from toxins with active urinary metabolites, such as plants from the family Liliaceae.24 In the present study, these species differences with regard to SPE data were illustrated by the most commonly reported exposure, namely chocolate for dogs and plants (Lilium spp) for cats. The study results suggested that owing to the considerable differences between these species, it may not be appropriate to group data derived from dogs and cats together for surveillance in the future, depending on the surveillance objectives. Further exploration of the differences in SPE reporting between these 2 species is warranted.

The most commonly implicated products associated with reported SPEs in the present study mirrored the availability, popularity, and use of those products in the human population. For example, the most commonly reported exposures of dogs and cats to human medicines involved drugs to treat CNS disorders, analgesics and pain killers, and cardiovascular drugs; these are currently the top 3 most common prescription drugs used by humans in the United States.25 In the present study, there was evidence that changes in the popularity of certain foods also impacts pet exposures to those products. Previous reports6,7 by US PCCs did not report avocados as a common exposure among cats. However, in the present study, avocados were the fourth most commonly reported food intended for human consumption to which cats were exposed, and this likely reflected the increasing popularity of avocados over the past few years. Finally, the number of SPEs involving exposure of dogs to cannabis or synthetic derivatives tripled during the study period, with an increase in the diversity of types of synthetic derivatives reported since 2010. Because this type of SPE was relatively common among dogs, future research to examine the effects of legalization of recreational and medical cannabis use in various states is warranted. The changes in the frequency of exposures to these products supported the routine examination of trends in toxicological exposures of pets to ensure veterinary care professionals are well informed and have knowledge that is up to date.

Although the results of the present study mostly concurred with data reported from other US PCCs, there were a few discrepancies. First, the proportion of SPEs attributable to pesticides was much lower in the present study than that previously reported by US PCCs.1,26 This difference was likely attributable to differences in pesticide classifications; in the present study, pesticides intended for topical use on companion animals were classified as veterinary pharmaceuticals, thereby decreasing the proportion of SPEs involving pesticides, compared with findings of other studies.1,7,26 Second, drugs intended to treat CNS disorders were the most common human pharmaceutical involved in SPEs reported to the APCC during the study period. Conversely, previous studies6,7,26 identified analgesics as the most commonly reported human medication exposure among pets. The high percentage of dogs and cats exposed to drugs intended to treat CNS disorders was likely a result of the widespread use of these medications in the US population; it has been estimated that since 2010, > 1 of every 5 adults have been taking ≥ 1 medication for psychological or behavioral disorders, and the prescribing rates of these medications have greatly increased over the past 15 years.27,28 Finally, the categories of agents responsible for the greatest proportion of deaths (or euthanasia) among dogs (eg, pet products and food, biocides, and foreign bodies) did not concur with previous US PCC findings, which identified that the greatest proportions of deaths were associated with exposures to pesticides, plants, and household products.1,6 Furthermore, many of the calculated CFRs in the present study were > 50.0% (eg, CFRs for fluorouracil, thioctic acid, bifenthrin, and bromethalin), which were much higher than CFRs ≤ 2% calculated in other studies.1,26 This discrepancy was likely related to differences in CFR calculation methods. In the present study, only SPEs with documented final outcomes were included in CFR calculations, which represented a fraction of the total exposures reported to the APCC. Other studies1,26 included all exposures in CFR calculations, regardless of the final outcome status, thereby resulting in much smaller CFRs as a result of much larger denominators. Although the extremely high CFRs calculated in the present study may have highlighted products that possibly represent serious poisoning risks to companion animals, the values may be somewhat inflated owing to the small number of cases that were available for the analysis as reflected by the wide 95% CIs for these estimates. Furthermore, if owners are more inclined to follow-up with the APCC for more serious outcomes, such as fatal exposures, the CFRs calculated in the present study would be inflated, compared with true ratios within the population, because serious outcomes would be overrepresented.

Interpretation of the results of the present study should be done in the light of inherent study limitations. First, because of the wide variation in reporting rates at the state level, it is possible that the exposures recorded in the APCC's animal toxin database may not have been representative of all hazardous exposures within the US companion animal population. However, given that there were numerous types of potentially hazardous substances reported to the APCC, including both common and rare exposures with short- and long-acting substances, the exposures reported likely provided a valid overview of toxicological exposures involving hazardous substances in the US companion animal population over the 10-year study period. Second, the APCC was probably subject to substantial underreporting of SPEs because of several factors, such as SES, owners’ pet health care–seeking behaviors, human-animal bond, awareness of the APCC and other PCCs, and public perception regarding substances that may be hazardous or toxic to pets. Furthermore, there may be substantial underreporting of common toxin exposures (eg, SPEs involving chocolate, marijuana, or ibuprofen) of dogs and cats by veterinarians because once veterinarians know how to treat a particular toxicosis, they will be less likely to call the APCC about such events in the future. Finally, it is important to note that all recorded exposures, regardless of their certainty measure, were included in analyses (ie, exposures with a low degree of certainty were not excluded from analysis). Therefore, it is possible that the identified trends may be more representative of the relative abundance of these products in home environments and not necessarily directly representative of the risk of exposure among companion animals in homes. However, > 60.0% of the exposures entered in the APCC's animal toxin database were assigned a high or moderate degree of certainty; thus, it was likely that the identified trends were representative of toxicological exposures among companion animals during the study period.

On the basis of the results of these analyses, certain points should be considered prior to use of data from the APCC animal toxin database for real-time surveillance of toxicological exposures among companion animals. Reporting of SPEs varied markedly among states, and reports submitted to the APCC should be examined at a finer geographic resolution (eg, county-level or census tract-level distribution) because large spatial gaps in the network of potential callers to the center need to be recognized when interpreting the results of analyses of these data. The results of the present study clearly highlighted differences in the types, routes, and seasonality of exposures between dogs and cats. This suggested that it may not be appropriate to group data for the 2 species together for surveillance in the future, depending on the surveillance objectives. Report submissions were found to be influenced by season and may also be influenced by other factors such as SES. Therefore, future studies should identify factors (eg, owners’ SES) that bias the reporting of SPEs involving dogs and cats to the APCC. These factors may need to be accounted for when applying traditional aberration detection methods (eg, spatial scan statistical analyses) to identify large-scale poisoning events because such factors may influence the data to an extent that important trends or disease clusters are masked. Finally, exposure certainty measures are likely important to consider when the database is used for various surveillance objectives. Therefore, future work should characterize the influence of certainty measures on the types of substances reported and determine whether there are any associations between particular certainty measures and toxic agents.

Acknowledgments

Supported by an infrastructure grant to Dr. David Pearl from the Canada Foundation for Innovation and the Ontario Research Fund as well as a research grant from the Natural Sciences and Engineering Research Council. Ms. Swirski was supported by the Ontario Veterinary College and Ontario Graduate Scholarship.

The authors declare that there were no conflicts of interest.

The authors thank Dr. Tina Wismer for invaluable insight throughout the project.

ABBREVIATIONS

APCC

Animal Poison Control Center

CFR

Case fatality ratio

IQR

Interquartile (25th to 75th percentile) range

PCC

Poison control center

SES

Socioeconomic status

SPE

Suspected poisoning event

Footnotes

a.

QGIS Geographic Information System software, version 2.16, QGIS. Available at qgis.osgeo.org. Accessed Nov 23, 2017.

b.

Stata 14 for Windows, Stata Corp, College Station, Tex.

c.

Microsoft Excel 2007 for Windows, Microsoft Corp, Redmond, Wash.

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Appendix

Categories used for general classification of agents and subclassification of human and veterinary pharmaceuticals associated with household-level SPEs involving dogs and cats reported in telephones calls from pet owners, veterinarians, and other PCCs to the US APCC in 2005 through 2014.

GeneralHuman pharmaceuticalsVeterinary pharmaceuticals
BiocidesAnalgesics and pain killersAnalgesics and pain killers
Bites and stingsAntimicrobials, antiseptics, and vaccinesAntimicrobials and antiseptics
Chemical agents for technical equipment, products, and processesAntihistaminesAntiparasitic drugs
Cleaning and maintenance productsAntineoplastic drugsDrugs to treat CNS disorders
Construction materialsBirth control products and contraceptivesDrugs to treat urinary incontinence
Consumer items and productsCardiovascular drugsTopically acting drugs
Cosmetics and personal care productsDrugs to treat CNS disordersVaccines
Dyes, paints, lacquers, and varnishesDrugs administered aurally, ocularly, or nasallyOther
Food intended for human consumptionDrugs to treat endocrine disorders 
Foreign bodiesDrugs to treat gastrointestinal disorders 
Fuels, flammable substances, and liquid scentsDrugs to treat musculoskeletal disorders 
Human and veterinary dietary supplementsDrugs to treat respiratory tract disorders 
Human medicinesImmunosuppressant drugs 
Pesticides, fertilizers, and plant protection agentsPrescription nutritional supplements 
Pet products, foods, and treatsTopically acting drugs 
Plants and wild mushroomsOther 
Tobacco and recreational or illicit drugs  
Unclassified medicines  
Veterinary medicines  
Other or unknown  

Exposure agents were classified into 20 general categories on the basis of a modified version of a previously published classification scheme.14 Subclassification of agents within the human medicine category was performed on the basis of a previously used classification scheme.3 For both human and veterinary medicines, subclassification included a subcategory of other, which included any agents that had > 1 primary indication.

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