The number of BYFCs has increased in urban and suburban areas over the past 10 years.1,2 These chickens are often kept as a source of fresh eggs and meat or as gardening partners assisting with pest control, and many are thought of and treated as household pets.1,2 There appears to be no specific demographic information available regarding BYFCs kept primarily as pets, and although backyard flock sizes can vary considerably, the authors’ observations have been that pet chickens seem to be commonly kept in smaller flocks that are predominately composed of hens. There has been an apparent increase in demand for veterinary care among BYFC owners, and this may reflect the fact that many BYFC owners regard their birds as they do other conventional companion animals, along with the likelihood of more direct and closer observation of individual chickens in the smaller-sized flocks. Poultry medicine has routinely focused on large-scale poultry production (eg, > 20,000 birds/flock), wherein the emphasis is less on individual chicken care and more on flock-based approaches. Veterinary school curricula have historically trained veterinarians in traditional large-scale poultry production. Thus, most small animal veterinarians have limited experience with poultry other than this training but may be asked to attend to individual pet chickens as patients. Large animal veterinarians, despite greater access to farm animals, also generally have limited experience with treating individual chickens. Avian veterinarians, although widely versed in the care of pet birds, may also have less experience with chickens than with more traditional pet birds, such as psittacines. As backyard poultry flocks have become more prevalent, some veterinary medical schools have introduced some medical training with a focus on pet chickens; however, there is limited information within the veterinary medical literature regarding the extent and usefulness of such training. Overall, studies are warranted to better understand the veterinary medical needs of BYFCs.
A recent survey revealed that most BYFC owners have been raising chickens for < 5 years and that many owners lack knowledge of common poultry health concerns.1 Respondents to the survey noted that they most often consulted the internet, books, magazines, or feed store personnel for information on poultry health and management.1 In addition, the stoic nature of chickens makes it challenging for pet owners and veterinarians to detect the early onset of clinical signs; hence, chickens are often evaluated for conditions that are quite advanced. For these reasons, chickens are often evaluated on an emergency basis and many require urgent care. To the authors’ knowledge, there are no reported studies that have assessed common problems and short-term outcomes among chickens that are evaluated on an emergency basis. The objective of the study reported here was to characterize the reasons for evaluation of and short-term outcomes for BYFCs that required urgent or emergency care at a veterinary teaching hospital.
Materials and Methods
Case selection and medical records review
The electronic medical records at the Cummings School of Veterinary Medicine, Tufts University, were searched for chickens that were evaluated by the emergency service from January 2014 through March 2017. The records were retrieved and reviewed; information obtained included each bird's age, sex, medical history, primary medical problem, flock size, final confirmed or working diagnosis, final outcome, and findings at necropsy when performed. Primary medical problems were classified as abnormal droppings, crop or gastrointestinal tract disease, lameness, neurologic disease, respiratory tract disease, reproductive tract disease, trauma, and nonspecific signs (ie, undefined illness). Descriptive statistics for chicken age and flock size were calculated.
Results
Seventy-eight BYFCs were evaluated on an emergency basis during the study period (Table 1). Most chickens were female (71 hens, pullets, and sexed chicks), with 3 reported as roosters. The sex was not recorded or known for 4 birds, of which 3 were chicks < 1 week old. The median age was 1 year (range, 0.1 to 7 years). The median flock size was 6 birds (range, 1 to 22 birds). Most chickens were living in a suburban or rural environment, with many accommodated in small coops in owners’ backyards. The reason for owning chickens was not widely recorded; however, when noted in the records, reasons included keeping the bird as pets or as a source of fresh eggs. No chickens were reported as being raised for meat production. Among the 78 BYFCs, the 2 most common primary medical problems leading to evaluation on an emergency basis were known or suspected trauma (n = 25 [32%]) and reproductive tract disease (10 [13%]).
Summary of results by disease category or reason for visit for 78 BYFCs evaluated on an emergency basis at a New England veterinary teaching hospital from January 2014 through March 2017.
| Outcome | |||||
|---|---|---|---|---|---|
| Disease category | Survival to hospital discharge | Death | Euthanasia | Treatment with antimicrobials | Necropsy diagnosis |
| Abnormal droppings (n = 3) | 2 | 1 | 0 | 0 | Visceral gout and renal inflammation (1) |
| Crop or gastrointestinal signs (n = 6) | 6 | 0 | 0 | 5 | NNP |
| Lameness (n = 6) | 2 | 0 | 4 | 2 | MD (1) |
| Neurologic signs (n = 6) | 1 | 0 | 5 | 1 | Visceral lymphoma (3) |
| Septic coelomitis (1) | |||||
| Open (1) | |||||
| Nonspecific signs (n = 11) | 4 | 0 | 7 | 4 | Visceral lymphoma (2) |
| Ovarian carcinoma with carcinomatosis (1) | |||||
| Pulmonary edema and coelomic hemorrhage (1) | |||||
| Respiratory tract signs (n = 5) | 2 | 0 | 3 | 2 | Aspergillus pneumonia with lymphoid atrophy (1) |
| Heterophilic to granulomatous bronchitis (1) | |||||
| Reproductive tract signs (n = 10) | 5 | 1 | 4 | 5 | Oviduct magnum prolapse with secondary necrosis (1) |
| Ovarian carcinoma (1) | |||||
| Fatty liver hemorrhagic syndrome (1) | |||||
| Trauma (n = 25) | 13 | 0 | 12 | 9 | NNP |
| Euthanasia (n = 6) | 0 | 0 | 6 | 0 | NNP |
| Total number of BYFCs | 35 | 2 | 41 | 28 | 16 |
Data provided represent the number of chickens.
NNP = Necropsies not performed.
Among the BYFCs evaluated because of trauma, the most common traumatic event was an attack by predators (11 chickens), including raptors (3 chickens) and dogs or foxes (6 chickens); 2 chickens had traumatic wounds consistent with predation, but the event was not witnessed and the cause of the trauma could not be verified. Three BYFCs that were housed singly had evidence of traumatic injuries that were presumed to be from accidental causes, including 1 bird with keel injuries and 2 birds with beak trauma of unknown origin. Two chickens were injured by human caretakers; one was accidently dropped by a young child and the other had a closed humeral fracture as a result of being restrained for oral administration of an herbal product. Two chickens were injured by other chickens. One bird had stepped on a thumbtack. The source of the trauma was unknown or not recorded for the remaining 6 chickens. No birds were suspected of sustaining nonaccidental injury, and there was no evidence of cockfighting. One chicken, which was in the coop when 2 other chickens were killed by a predator, had no external wounds identified. Among the 25 BYFCs with trauma, 12 were euthanized because of the severity of their injuries and 13 were discharged from the hospital after wound care. Six of the 13 noneuthanized birds underwent sedation or anesthesia for wound care.
Eleven BYFCs were evaluated for an undefined illness. Of the 11 birds with nonspecific signs, 7 were euthanized, and 4 were discharged from the hospital. Of the 4 surviving birds, 1 was taken out of the hospital by the owner prior to undergoing diagnostic testing, 2 were suspected of having reproductive tract disease (coelomic mass and presumed salpingitis), and 1 was noted to have respiratory tract signs. Four of the 7 euthanized chickens underwent necropsy. Two of those birds were identified as having visceral lymphoma consistent with MD. One bird had an ovarian carcinoma with carcinomatosis and concurrent impaction of the ventriculus, and the other bird (a 6-week-old chick) had mild to moderate pulmonary edema and coelomic hemorrhage of unknown origin. Of the 3 birds that were euthanized and did not undergo necropsy, 2 were suspected of having reproductive tract disease (egg binding or coelomic mass and egg yolk coelomitis) and 1 was presumed to have renal disease.
Ten BYFCs were evaluated on an emergency basis because of known or suspected reproductive tract disease. The median age of birds with reproductive tract disease was 1.75 years (range, 0.42 to 4 years). Five chickens had a cloacal prolapse associated with egg laying or egg binding, 3 chickens were suspected to be egg-bound by the attending clinician, 1 chicken laid an unshelled egg, and 1 chicken had swelling of the soft tissue associated with its vent. Five birds were discharged from the hospital; 4 other birds were euthanized, and another bird died. Three of the latter 5 chickens were necropsied; 2 birds had cloacal prolapse as the primary medical problem with confirmation of an oviduct magnum prolapse with secondary necrosis and congestion for one and an ovarian carcinoma for the other. The third chicken that underwent necropsy was initially evaluated because of suspicion of being egg-bound; the diagnosis for that bird was fatty liver hemorrhagic syndrome without any concurrent reproductive tract abnormalities.
Six BYFCs were evaluated on an emergency basis because of suspected neurologic disease. Of these 6 birds, 5 were euthanized and 1 (which was dragging a leg) was found to have a healing tibiotarsal fracture and was discharged from the hospital. All 5 birds that were euthanized underwent necropsy. Three of the 5 birds had visceral lymphoma consistent with MD, 1 had septic coelomitis, and 1 had no specific gross lesions.
Six BYFCs were evaluated on an emergency basis because of lameness. Four birds were euthanized. Of those 4 birds, 1 had a limb deformity since hatching, 1 had severe frostbite involving the scaled portions of both legs, 1 had suspected MD (on the basis of other flock deaths), and 1 had evidence of MD detected during necropsy. One of the 2 surviving birds with lameness that were discharged from the hospital had severe pododermatitis, and the other bird had severe degenerative joint disease.
Six BYFCs were evaluated on an emergency basis because of suspected gastrointestinal tract disease, including crop impaction. All 6 chickens were discharged from the hospital. Five chickens had gastrointestinal stasis with concurrent crop impaction or stasis. Three of those 5 birds were tested for possible lead toxicosis and had blood lead concentrations of 9.9, 10.3, and 43 μg/dL. A diagnosis was not made for the remaining 4 chickens with suspected gastrointestinal stasis, including the 2 birds with lower blood lead concentrations. One chick (approx 3 weeks old) had eaten part of a string, and the remainder was hanging from its beak; the string was manually removed, and the bird was discharged from the hospital.
Five BYFCs were evaluated on an emergency basis for a primary medical problem of respiratory distress; of those birds, 3 were euthanized, 1 was discharged from the hospital against medical advice, and 1 was discharged from the hospital on the understanding that the owner would have the bird euthanized and necropsied at another facility. Two of the 3 euthanized birds underwent necropsy. One bird had Aspergillus pneumonia and concurrent lymphoid atrophy; the other had moderate heterophilic to granulomatous bronchitis without an identifiable etiologic agent, and its condition was suspected to be related to possible aspiration events.
Three chickens were evaluated on an emergency basis because of abnormal droppings, as assessed by the 3 owners. Two were treated as outpatients without further diagnostic investigation or characterization of the droppings. One chicken with an initial primary problem of hematochezia died during the examination, and visceral gout and a renal injury of unknown cause were confirmed during necropsy.
Overall, 35 of 78 (45%) BYFCs were discharged from the hospital following the emergency visit. Of those 78 chickens, 41 (53%) were euthanized and 2 died. Of the 43 deceased birds, 16 underwent necropsy; the carcasses of 14 birds were disposed of via cremation. Thirteen birds were taken home for planned burial following euthanasia. Six birds were brought to the emergency service for euthanasia only, presumably for quality-of-life issues; however, the reason for euthanasia was not always recorded but included MD in the flock, myiasis, and suspected neoplasia. Unfortunately, none of these birds underwent necropsy, and a final diagnosis could not be determined in those cases.
Of the 35 BYFCs that were discharged from the hospital, 28 were prescribed systemic antimicrobial treatment (Table 1). Twenty-three chickens received amoxicillin trihydrate–clavulanate potassium,a 2 chickens received long-acting ceftiofur,b 2 received enrofloxacinc with 1 of those birds also receiving ampicillin, 1 chicken received ampicillin-sulbactam, and 1 chicken received trimethoprim-sulfamethoxazole. Fourteen of the discharged BYFCs were prescribed oral treatment with meloxicam, of which 9 birds were evaluated because of trauma, 4 birds were evaluated because of reproductive tract disease, and 1 bird was evaluated because of lameness. One chicken that was evaluated because of trauma also received an IM injection of butorphanol tartrate prior to hospital discharge. One chicken with reproductive tract disease that received an IM injection of butorphanol prior to hospital discharge was not given any additional analgesic medication. Prior to hospital discharge, another chicken received IM injections of butorphanol and midazolam as a sedative for crop lavage for the management of crop stasis. After discharge from the hospital, no further follow-up information was available for any bird that was treated with antimicrobials, likely because of the inherent nature of emergency service visits.
Discussion
In the present study, BYFCs were evaluated on an emergency basis most commonly for issues related to trauma and reproductive tract disease, although many had nonspecific signs of illness. Consistent with prior reports, trauma as a result of predation and other environmental issues were common reasons for emergency service visits.2 Compared with findings for dogs and cats, there were fewer blunt trauma injuries among the BYFCs of the present study, with only 1 chicken being injured by a falling coop. Trauma in dogs and cats may be assessed by use of the animal trauma triage score3; this has not been assessed in chickens to date. Moreover, although the Veterinary Council on Trauma (as part of the American College of Veterinary Emergency and Critical Care) maintains a national database on small animal trauma, this database does not include chickens.4 In a survey2 of owners of BYFCs, curbing predation was the most commonly cited challenge in terms of poultry management. Therefore, it is important for emergency veterinary clinicians to review enclosure details when discussing prevention of further traumatic injuries with chicken owners. In the present study, predation by raptors, such as hawks that are active during daylight hours, occurred in several cases of traumatic injuries; however, many of the reported predator attacks involved nocturnal animals and could have been minimized by keeping chickens in a predator-proof enclosure at night. Close supervision of interactions with small children and other pets, such as dogs, is also advised to minimize traumatic injuries to pet chickens. Chickens may also inflict traumatic injuries on one another. Most flocks establish a social order with dominant chickens receiving priority access to food and nesting locations; disruption of this social order by the addition of new hens to the flock may increase the incidence of chickens fighting with each other during reestablishment of their pecking order.
Traumatic wound care in chickens is often straightforward and uses management strategies similar to those applied to wounded dogs and cats. Chickens may be sedated or anesthetized for wound care. Chickens are relatively easy to intubate given that their glottis is readily accessible near the base of the tongue, although it is important to remember that birds have complete tracheal rings and thus only uncuffed endotracheal tubes should be used in avian species. Chickens tolerate inhalational anesthesia with few complications; however, in heavily sedated or anesthetized chickens, patient positioning is an important consideration. Placement of a chicken on its side allows for proper ventilation, whereas placement of a chicken on its back makes it very difficult for the bird to expand its chest because of the heavy keel and large thoracic pectoral muscles. In addition, care should be taken to briefly withhold food from the patient or empty crop contents, as needed, to reduce the chance of aspiration associated with sedation and anesthesia. Intravenous catheters may be placed in the ulnar, tibiotarsal, or right jugular vein to provide vascular access and facilitate concurrent fluid administration to chickens requiring additional support during anesthesia. In the present study, most chickens undergoing traumatic wound care were prescribed antimicrobial treatment and meloxicam, and 1 bird only concurrently received an injection of butorphanol for pain management.
Reproductive tract disease was also common in BYFCs that were evaluated on an emergency basis in the present study. On the basis of the primary medical problem at the time of the visit to the emergency service, only 10 of 78 (12.8%) chickens were assumed to have reproductive tract disease; however, further assessment of all chickens in the study revealed that 17 of 78 (21.8%) had presumed or confirmed concurrent reproductive tract disease. Most BYFCs are hens, which are kept not only for their egg-laying abilities but also likely because of their communal nature and lack of excessive vocalizations. Many urban areas also have legal restrictions on the ownership of roosters. Given that hens are routinely kept in backyard flocks as a source of fresh eggs, it is not uncommon for chicken owners to seek veterinary care when a hen suddenly stops laying eggs. Egg binding or dystocia, abnormal eggs, and cloacal prolapse are common in smaller flocks, likely a consequence of close observation of individual chickens by the owners. Pullets are considered hens once they begin laying eggs at approximately 18 to 21 weeks of age; however, a few breeds do not reach sexual maturity until closer to 6 months of age. Pullets younger than the age of expected sexual maturity are unlikely to develop reproductive tract disease. In the present study, this was reflected in the median age of BYFCs with reproductive tract problems (1.75 years; range, 0.42 to 4 years). Unlike commercial-production hens whose life span is limited by traditional poultry production practices, BYFCs typically have greater longevity as pets and are more likely to develop reproductive tract disease, such as neoplasia, egg-related coelomitis, oviductal impaction, and persistent right oviducts, and undergo age-related decreases in egg production.2 Reproductive tract health is important in pet hens because these birds lay eggs for many years, with some hens laying eggs until ≥ 10 years of age, albeit at a much lower frequency than that among younger hens. Chickens can undergo salpingohysterectomy with possible partial ovariectomy as a means of managing reproductive tract disease; understandably, this procedure ends egg production and is not routinely performed in hens in backyard flocks.
Marek disease is a major cause of death among BYFCs, and affected birds are commonly perceived by their owners as having lameness, neurologic disease, or vague illness.5 The disease is caused by a highly contagious and environmentally resistant alphaherpesvirus. Of the 3 serotypes, MDV-1 is considered to be pathogenic and associated with MD.5 Because there is no effective treatment for MD in poultry, vaccination is the primary means of control. Commercial poultry chicks are routinely vaccinated at 1 day of age or receive a vaccine in ovo as an 18-day-old embryo. These vaccines inhibit the development of MDVinduced lymphoma, although viral replication of and infection with MDV-1 still occur.6 Although chicks obtained directly from commercial sources may be vaccinated, many owners of pet BYFCs do not vaccinate their chicks against MD, in part because the vaccine is typically only sold in large-scale dosing formulations and many chicken owners are unaware of the need to vaccinate young chicks or embryos.
Marek disease typically affects young chickens between the ages of 10 and 20 weeks but can develop in birds outside this age range, often in unvaccinated flocks, as an acute form that can rapidly lead to high mortality rates.2 There are several forms of MD that are associated with various clinical signs. Classic MD is characterized by neurologic changes including paresis or paralysis and vague signs associated with the development of visceral lymphoma. There is also an ocular form that results in lymphocyte infiltration of the iris and a cutaneous form that causes feather follicle changes. Of the 6 chickens that had necropsy findings consistent with MD in the present study, 3 were evaluated because of neurologic signs, 2 were evaluated because of nonspecific signs of illness, and 1 was evaluated because of lameness. One chicken for which the primary medical problem was lameness was also suspected of having MD because of the presence of MD within the flock; however, this chicken did not undergo necropsy after euthanasia. Marek disease can be difficult to differentiate from the neoplastic changes induced by avian leukosis virus (another important infectious agent among chickens), and often additional molecular testing is required to confirm a diagnosis. Avian leukosis virus typically causes lymphoid leukosis in infected chickens, although numerous other forms can develop. Unlike MD, avian leukosis virus infection rarely causes clinical signs of lymphoid leukosis prior to 14 weeks of age. Marek disease virus is only transmitted horizontally, whereas avian leukosis virus can be transmitted both horizontally and vertically (through the egg) and has the potential to be controlled via vaccination strategies.7 Unfortunately, there is no treatment for and no effective vaccine against avian leukosis virus.
Vaccination of 1-day-old chicks against MD is recommended for pet BYFCs, and no booster vaccines are required. Vaccination is generally beyond the scope of emergency medicine, but a thorough history should involve inquiring about the vaccination status of individual chickens as well as the flock to determine the potential for MD contributing to nonspecific signs of illness. Other vaccines, which are not commonly administered but may be in some situations, are those against Newcastle disease, infectious bronchitis, infectious laryngotracheitis, salmonellosis, mycoplasmosis, and fowlpox. Knowledge of the vaccination status of avian patients can assist emergency clinicians in determining the overall risk of these diseases in birds evaluated on an emergency basis.
In the present study, 5 owners brought a chicken to the emergency service for treatment of suspected respiratory tract disease. Respiratory distress was associated with a high mortality rate (ie, euthanasia of 3/5 birds). The cause of respiratory distress was unknown in all affected birds. The most common respiratory tract disease in chickens is generally nonspecific and considered to be husbandry related.8 In such cases, there is no known infective agent, and clinical signs likely develop secondary to high environmental ammonia or dust concentrations or changes to the bacterial flora within the bird's respiratory tract.8 Common infectious causes are infectious laryngotracheitis virus, Avibacterium paragallinarum (the causative agent of infectious coryza), and Mycoplasma gallisepticum. Mycoplasmosis is one of the most common respiratory tract diseases that affect BYFCs. This was supported by results of a recent postmortem survey of poultry in back yard flocks that indicated that M gallisepticum was the second most common infective agent identified.9 Typical respiratory tract signs in chickens include oculonasal discharge, coughing, sneezing, and periocular swelling consistent with sinusitis. Stress, concurrent infections, and underlying immunosuppression may contribute to development of disease in individual chickens in a flock of birds with latent mycoplasmosis. Although respiratory tract disease in BYFCs is frequently attributable to mycoplasmosis, other infectious bacterial agents, including Pasteurella spp, Escherichia coli, and Pseudomonas spp, should be considered.8 Viral diseases, such as mesogenic Newcastle disease,10 low-pathogenicity avian influenza, and infectious laryngotracheitis, should also be considered as causes of respiratory tract disease in chickens. When in doubt, veterinarians who attend birds with a potentially infectious disease should contact the appropriate state veterinarian for guidance; some diseases (eg, avian influenza and exotic Newcastle disease) are reportable regardless of the region in the United States, and other diseases may be reportable in individual states.10,11 In more moderate climates, parasitic causes of respiratory tract disease, such as tracheal worms (Syngamus trachea), are more common, and more intensive housing may be associated with more widespread infectious respiratory tract disease.12
Crop abnormalities are commonly observed by chicken owners and are usually a marker of underlying gastrointestinal tract or systemic disease. In the present study, this was supported by the fact that 5 of the 6 chickens evaluated for gastrointestinal tract disease had an abnormal crop appearance. Although true crop impaction that requires medical intervention can develop (often a result of ingestion of pebbles, long grasses, or fibers), apparent crop impactions are far more commonly attributable to gastrointestinal tract stasis or ileus. In birds with ileus, the muscles of the crop stretch and become weak, creating a pendulous appearance of the crop and resulting in clinical crop stasis in the absence of any obstructing foreign material. One of the birds that was evaluated because of gastrointestinal tract disease in the present study had a blood lead concentration of 43 μg/dL and was presumed to have gastrointestinal tract dysfunction secondary to lead toxicosis. Although a blood lead concentration of this magnitude may contribute to gastrointestinal tract signs in other species, it is unclear whether this is true for chickens, especially given that they have long-term exposure to lead-contaminated soils. In a recent survey of BYFCs representing 30 flocks in the New England region, 40 of 57 (70.2%) chickens had detectable concentrations of lead in collected blood samples (mean blood lead concentration, 12.49 μg/dL [median, 7.5 μg/dL; range, 1.65 to > 65.0 μg/dL), yet none of the surveyed chickens had clinical evidence of lead toxicosis.d Further research is needed to determine whether there is a direct correlation between cases of gastrointestinal tract dysfunction in chickens and blood lead concentration.
Several birds of the present study were evaluated on an emergency basis because of owner-reported abnormal droppings. Although the description and assessment of eliminations can assist in localizing a disease process in dogs and cats, localization of disease on the basis of characteristics of droppings in avian species can be more challenging. Given that birds have a cloaca that serves as the terminal portion of the gastrointestinal, urinary, and reproductive tracts, it can be difficult for owners and veterinarians to differentiate between a reproductive, gastrointestinal, or urinary tract disease solely on the basis of the appearance of droppings. Typical chicken droppings include 3 components: feces, solid white urates, and liquid urine. For a given bird, the fecal component can vary dramatically in color and appearance because of several factors including diet, time of day, season, and the bird's health status. Adult chickens often have no clinical signs for many of the bacterial diseases that contribute to diarrhea in young chickens, including those caused by Salmonella spp, Clostridium spp, and Campylobacter jejuni. In the present study, 2 of the BYFCs that were evaluated because of abnormal droppings were discharged from the hospital with an open diagnosis. One chicken that was evaluated because of bloody droppings and initially presumed to have gastrointestinal tract disease died shortly after arrival at the hospital. On necropsy, visceral gout and concurrent renal injury and inflammation were present with no apparent definitive cause of hematochezia, which further emphasizes the innate challenges in diagnosing the underlying cause of abnormal droppings in avian species. Visceral gout in that bird may have been attributable to 1 or more factors, such as nutritional issues, lack of available water sources, ingestion of mycotoxins, systemic viral infection, or even underlying enteritis caused by coccidiosis.
As for all species, nonspecific signs are relatively common as the reason for examination. In backyard flocks, birds may appear lethargic or do not eat as much as usual but have no localizing clinical signs. In such cases, determination of the underlying cause can be very difficult without further diagnostic testing or necropsy to obtain a definitive diagnosis. However, following examination and other diagnostic testing of 11 BYFCs with nonspecific signs in the present study, a presumptive diagnosis was made for 8 of 11 birds. Similar to a cat or dog that is perceived to be vaguely ill, to obtain a diagnosis for a chicken with nonspecific signs may require examination, review of its history, and diagnostic testing, including diagnostic imaging and laboratory testing.
Forty-one of the 78 (53%) BYFCs evaluated on an emergency basis in the present study were euthanized because of the severity of illness or trauma. Compared with other smaller avian species, euthanasia of chickens is a relatively straightforward procedure, given the ease of obtaining vascular access. Chickens, particularly sick chickens, are generally easy to restrain and have prominent right jugular and tibiotarsal veins that are easily accessible for injection of euthanasia solution when indicated. Often inhalational anesthesia can be provided prior to euthanasia to minimize stress and handling issues in less debilitated chickens. Thirteen of the chickens that were euthanized were taken home for burial by their owners. As for all euthanized animals that undergo burial, the presence of pentobarbital or phenytoin in the carcass could represent a risk to other animals. Owners taking home their chicken following euthanasia should be advised of this risk and informed of the fact that many local legal statutes dictate the terms of proper burial.
Although extralabel use of medications is common in dogs and cats, clinicians should be reminded that for food animal species, even those kept as pets, there are FDA mandates dictating the acceptable use of many medications. The AVMA has a helpful algorithm that veterinarians can follow when contemplating extralabel use of drugs (notably antimicrobials) in species such as chickens.13 In obvious contrast to the situation for dogs and cats, it is essential for veterinarians and owners to be cognizant of meat and egg withdrawal times after giving any medications to chickens. The Food Animal Residue Avoidance Databank provides current guidelines regarding withdrawal times; however, these regulations are constantly changing, and it is very important to consult the guidelines prior to prescribing medications for the treatment of chickens. In the present study, systemic antimicrobials were prescribed for 28 of the 35 chickens that were discharged from the hospital. Unfortunately, given the nature of most emergency service visits and the retrospective nature of the present study, follow-up information was not available for the chickens that were discharged from the hospital and were to be treated with antimicrobials by the owners. Potentiated penicillins, which can be legally administered to chickens, were most commonly prescribed. For chickens, the egg and meat withdrawal times for potentiated penicillins are both 8 weeks. In contrast, fluoroquinolones, cephalosporins, and metronidazole are not approved for use in chickens. Surprisingly, 2 chickens in the present study were treated systemically with enrofloxacin despite our hospital policy that forbids the use of fluoroquinolones in chickens. There are many other drugs that are prohibited with zero tolerance of use in chickens, such as chloramphenicol, clenbuterol, diethylstilbestrol, glycopeptides (including vancomycin), nitroimidazoles, and nitrofurans. These are all FDA group 1 drugs; as such, there is no allowance for their extralabel use in any food-producing animals, including chickens.
It is important to note that limitations of the study reported here included the retrospective nature of the data collected and the potential for incomplete medical record details (especially as a consequence of the innate rapid pace of a busy emergency service). Moreover, the types of emergency evaluations were impacted by geographic location of the veterinary teaching hospital in terms of local distribution of endemic diseases, potential predators, environmental factors, and seasonal influences.
Results of the present study indicated that BYFCs were evaluated on an emergency basis for a wide variety of problems ranging from very obvious trauma, respiratory tract signs, or neurologic signs to vague and nonspecific signs. It is helpful when clinicians understand the common diseases (along with possible short-term outcomes) that affect chickens, thereby facilitating the medical approach to such cases in an emergency room setting.
ABBREVIATIONS
| BYFC | Backyard flock chicken |
| MD | Marek disease |
| MDV | Marek disease virus |
Footnotes
Clavamox, Zoetis, Kalamazoo, Mich.
Excede, Zoetis, Kalamazoo, Mich.
Baytril, Bayer, Shawnee Mission, Kan.
Rosenbaum MH, Research Assistant Professor, Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, Mass: Personal communication, 2017.
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