OBJECTIVE To determine the seroprevalence of heartworm infection, risk factors for seropositivity, and frequency of prescribing heartworm preventives for cats.
DESIGN Prospective cross-sectional study.
ANIMALS 34,975 cats from 1,353 veterinary clinics (n = 26,707) and 125 animal shelters (8,268) in the United States and Canada.
PROCEDURES Blood samples were collected from all cats and tested with a point-of-care ELISA for Dirofilaria immitis antigen, FeLV antigen, and FIV antibody. Results were compared among geographic regions and various cat groupings.
RESULTS Seropositivity for heartworm antigen in cats was identified in 35 states but not in Canada; overall seroprevalence in the United States was 0.4%. Seroprevalence of heartworm infection was highest in the southern United States. A 3-fold increase in the proportion of seropositive cats was identified for those with (vs without) outdoor access, and a 2.5-fold increase was identified for cats that were unhealthy (vs healthy) when tested. Seroprevalence was 0.3% in healthy cats, 0.7% in cats with oral disease, 0.9% in cats with abscesses or bite wounds, and 1.0% in cats with respiratory disease. Coinfection with a retrovirus increased the risk of heartworm infection. Heartworm preventives were prescribed for only 12.6% of cats at testing, and prescribing was more common in regions with a higher seroprevalence.
CONCLUSIONS AND CLINICAL RELEVANCE At an estimated prevalence of 0.4%, hundreds of thousands of cats in the United States are likely infected with heartworms. Given the difficulty in diagnosing infection at all clinically relevant parasite stages and lack of curative treatment options, efforts should be increased to ensure all cats receive heartworm preventives.
Objective—To evaluate the use of the anesthetic
combination tiletamine, zolazepam, ketamine, and
xylazine (TKX) for anesthesia of feral cats at largescale
Animals—7,502 feral cats.
Procedure—Cats were trapped by their caretakers
for a feral cat neutering program from July 1996 to
August 2000. The anesthetic combination TKX was
injected IM into cats while they remained in their
traps. Each milliliter of TKX contained 50 mg of tiletamine,
50 mg of zolazepam, 80 mg of ketamine, and
20 mg of xylazine. Females were spayed by veterinarians,
whereas males were castrated by veterinarians
or veterinary students. Yohimbine (0.5 mg, IV)
was administered at the end of the procedure. Logs
were kept of the individual drug doses, signalment of
the cats, and any complications encountered. These
data were analyzed retrospectively (1996 to 1999)
and prospectively (2000).
Results—Of the 5,766 cats for which dosing records
were complete, 4,584 (79.5%) received a single
dose of TKX. The mean initial dose of TKX was 0.24
± 0.04 ml/cat, and the total mean dose of TKX was
0.27 ± 0.09 ml. Overall mortality rate was 0.35%
(26/7,502) cats, and the death rate attributable solely
to potential anesthetic deaths was 0.23% (17/7,502)
Conclusions and Clinical Relevance—The use of TKX
for large-scale feral cat neutering clinics has several
benefits. The TKX combination is inexpensive, provides
predictable results, can be administered quickly and
easily in a small volume, and is associated with a low
mortality rate in feral cats. (J Am Vet Med Assoc 2002;
Objective—To evaluate the use of adult cat serum as
an immunoglobulin supplement in kittens with failure
of passive transfer.
Design—Randomized controlled study.
Animals—11 specific pathogen-free queens and their
Procedure—Kittens were removed from the queens at
birth, prior to suckling colostrum, and randomly
assigned to 1 of 4 groups: colostrum-deprived,
colostrum-fed, colostrum-deprived and administration
of pooled adult cat serum IP, and colostrum-deprived
and administration of pooled adult serum SC.
Colostrum-fed kittens were returned to the queen and
allowed to suckle normally. Colostrum-deprived kittens
were isolated from the queen and fed a kitten milk
replacer for 2 days to prevent absorption of colostral
IgG. All colostrum-deprived kittens were returned to
the queen on day 3. Serum IgG concentrations were
measured by radial immunodiffusion in the kittens at
birth and 2 days and 1, 2, 4, 6, and 8 weeks after birth.
Results—None of the kittens had detectable
serum IgG at birth. Both IP and SC administration
of adult cat serum resulted in peak serum IgG concentrations
equivalent to those in kittens that suckled
normally. Untreated colostrum-deprived kittens
did not achieve serum IgG concentrations comparable
to those for kittens in the other groups until 6
weeks of age.
Conclusions and Clinical Relevance—Results suggest
that adult cat serum may be used as an
immunoglobulin supplement in colostrum-deprived kittens.
Although the minimum concentration of IgG necessary
to protect kittens from infection is unknown,
concentrations achieved were comparable to those in
kittens that suckled normally. (J Am Vet Med Assoc 2001;219:1401–1405)
Objective—To determine prevalence of FeLV infection
and serum antibodies against feline immunodeficiency
virus (FIV) in unowned free-roaming cats.
Design—Cross-sectional serologic survey.
Animals—733 unowned free-roaming cats in
Raleigh, NC, and 1,143 unowned free-roaming cats in
Results—In Raleigh, overall prevalence of FeLV infection
was 5.3%, and overall seroprevalence for FIV
was 2.3%. In Gainesville, overall prevalence of FeLV
infection was 3.7%, and overall seroprevalence for
FIV was 4.3%. Overall, FeLV prevalence was 4.3%,
and seroprevalence for FIV was 3.5%. Prevalence of
FeLV infection was not significantly different between
males (4.9%) and females (3.8%), although seroprevalence
for FIV was significantly higher in male
cats (6.3%) than in female cats (1.5%).
Conclusions and Clinical Relevance—Prevalence of
FeLV infection and seroprevalence for FIV in unowned
free-roaming cats in Raleigh and Gainesville are similar
to prevalence rates reported for owned cats in the
United States. Male cats are at increased risk for
exposure to FIV, compared with female cats. (J Am
Vet Med Assoc 2002;220:620–622)
Objective—To determine the prevalence and severity
of pulmonary arterial lesions in cats seropositive for
heartworms (Dirofilaria immitis) but lacking adult
heartworms in the heart and lungs during necropsy.
Animals—630 adult cats from an animal control shelter
Procedure—Cats were tested for adult heartworms
in the heart and pulmonary arteries and antibody
against heartworms in the serum. Histologic examination
was conducted on the right caudal lung lobe of
24 heartworm- and antibody-positive cats; 24 heartworm-negative and antibody-positive cats; and 24
heartworm-, antibody-, and antigen-negative cats.
Wall areas of 10 small to medium-sized pulmonary
arteries of each cat were measured and expressed as
a proportion of total cross-sectional area.
Results—Heartworm infection or seropositive status
was significantly and strongly associated with severity
of medial hypertrophy of pulmonary arterial walls.
Heartworm- and antibody-positive cats and heartworm-negative and antibody-positive cats had a significant
increase in wall thickness, compared with
wall thickness for heartworm- and antibody-negative
cats. Heartworm- and antibody-positive cats had the
most severe hypertrophy. The proportion with occlusive
medial hypertrophy was significantly higher in
heartworm- and antibody-positive cats (19/24 [79%])
and heartworm-negative and antibody-positive cats
(12/24 [50%]), compared with heartworm- and antibody-negative cats (3/24 [13%]).
Conclusions and Clinical Relevance—Cats with
serologic evidence of exposure to heartworms,
including those without adult heartworms in the lungs
and heart, have a greater prevalence of pulmonary
arterial lesions than heartworm-negative cats without
serologic evidence of exposure. Additional studies are
needed to define the pathogenesis, specificity, and
clinical importance of these lesions. (Am J Vet Res
Objective—To determine the pharmacokinetics of
enrofloxacin in neonatal kittens and compare the pharmacokinetics
of enrofloxacin in young and adult cats.
Animals—7 adult cats and 111 kittens (2 to 8 weeks
Procedure—A single dose of 5 mg of enrofloxacin/kg
was administered to adults (IV) and kittens (IV, SC, or
PO). Plasma concentrations of enrofloxacin and its
active metabolite, ciprofloxacin, were determined.
Results—The half-life of enrofloxacin administered IV
in 2-, 6-, and 8-week-old kittens was significantly
shorter and its elimination rate significantly greater
than that detected in adults. The apparent volumes of
distribution were lower at 2 to 4 weeks and greater at
6 to 8 weeks. This resulted in lower peak plasma concentration
(Cmax) at 6 to 8 weeks; however, initial plasma
concentration was within the therapeutic range
after IV administration at all ages. Compared with IV
administration, SC injection of enrofloxacin in 2-weekold
kittens resulted in similar Cmax, half-life, clearance,
and area under the curve values. Enrofloxacin administered
via SC injection was well absorbed in 6- and 8-
week-old kittens, but greater clearance and apparent
volume of distribution resulted in lower plasma concentrations.
Oral administration of enrofloxacin resulted
in poor bioavailability.
Conclusions and Clinical Relevance—In neonatal
kittens, IV and SC administration of enrofloxacin provided
an effective route of administration. Oral administration
of enrofloxacin in kittens did not result in
therapeutic drug concentrations. Doses may need to
be increased to achieve therapeutic drug concentrations
in 6- to 8-week-old kittens. ( Am J Vet Res 2004;65:350–356)
Objective—To determine whether passive transfer of
IgG in neonatal kittens affects plasma opsonic capacity
and neutrophil phagocytic and oxidative burst
responses to bacteria in vitro.
Animals—22 kittens from 6 specific pathogen-free
Procedure—Kittens were randomized at birth into the
following treatment groups: colostrum-fed,
colostrum-deprived, or colostrum-deprived supplemented
with feline or equine IgG. Blood samples
were collected at intervals from birth to 56 days of
age. Plasma IgG concentrations were determined by
radial immunodiffusion assay. Neutrophil function
was assessed by a flow cytometry assay providing
simultaneous measurement of bacteria-induced
phagocytosis and oxidative burst. The opsonic capacity
of kitten plasma was determined in an
opsonophagocytosis assay with bacteria incubated in
untreated or heat-inactivated plasma.
Results—Among treatment groups, there were no
significant differences in neutrophil phagocytic and
oxidative burst responses to bacteria or opsonic
capacity of plasma. In all samples of plasma, inactivation
of complement and other heat-labile opsonins
significantly reduced the opsonic capacity. Plasma
IgG concentrations in kittens did not correlate with
neutrophil function or plasma opsonic capacity before
or after inactivation of complement.
Conclusions and Clinical Relevance—The plasma
opsonic capacity and neutrophil phagocytic and oxidative
burst responses in vitro of kittens receiving passive
transfer of IgG via colostrum intake or IgG supplementation
and those deprived of colostrum were similar.
The alternate complement pathway or other heat-labile
opsonins may be more important than IgG in bacterial
opsonization and phagocytosis. ( Am J Vet Res
Objective—To determine the prevalence of infectious diseases of animal and zoonotic importance in cats and dogs rescued and transferred from the Gulf Coast region following Hurricane Katrina.
Animals—414 dogs and 56 cats rescued and transferred from the Gulf Coast region within 4 months after the hurricane.
Procedures—EDTA-anticoagulated blood and serum samples were tested via PCR and serologic assays for infectious diseases.
Results—In dogs, prevalence was highest for anti-West Nile virus (WNV) antibodies (218/390 [55.9%]), Dirofilaria immitis antigen (195/400 [48.8%]), anti-Toxoplasma gondii antibodies (92/366 [25.1%]), and hemotropic mycoplasma DNA (40/345 [11.9%]). The DNA of Bartonella spp, Ehrlichia spp, or Babesia spp or anti-canine influenza virus antibodies were identified in < 2% of dogs. In cats, prevalence was highest for antibodies against Bartonella spp and DNA of Bartonella spp combined (49/55 [89.1 %]), anti–T gondii antibodies (13/55 [23.6%]), hemotropic mycoplasma DNA (5/47 [10.6%]), anti-WNV antibodies (5/48 [10.4%]), D immitis antigen (4/50 [8.0%]), and anti–FIV antibodies (4/56 [7.1%]). A total of 308 (74.4%) dogs and 52 (92.9%) cats had evidence of previous or current vector-borne infections.
Conclusions and Clinical Relevance—Cats and dogs rescued from the disaster region had evidence of multiple infectious diseases. The dispersal of potentially infectious animals to other regions of North America where some infections were not typically found could have contributed to new geographic ranges for these organisms or to underdiagnosis in affected animals because of a low index of suspicion in regions with low disease prevalence.
Objective—To determine the effects of anesthesia and surgery on serologic responses to vaccination in kittens.
Design—Prospective controlled trial.
Animals—32 specific-pathogen–free kittens.
Procedures—Kittens were assigned to 1 of 4 treatment groups: neutering at 7, 8, or 9 weeks of age or no neutering. All kittens were inoculated with modified-live virus vaccines against feline panleukopenia virus (FPV), feline herpesvirus (FHV), and feline calicivirus (FCV) at 8, 11, and 14 weeks of age and inactivated rabies virus (RV) at 14 weeks of age. Serum antibody titers against FPV, FHV, and FCV were determined at 8, 9, 11, 14, and 17 weeks of age; RV titers were determined at 14 and 17 weeks of age.
Results—Serologic responses of kittens neutered at the time of first vaccination (8 weeks) were not different from those of kittens neutered 1 week before (7 weeks) or 1 week after (9 weeks) first vaccination or from those of kittens that were not neutered. In total, 31%, 0%, 69%, and 9% of kittens failed to develop adequate titers against FPV, FCV, FHV, and RV, respectively, by 17 weeks of age.
Conclusions and Clinical Relevance—Neutering at or near the time of first vaccination with a modified-live virus vaccine did not impair antibody responses in kittens. Many kittens that were last vaccinated at 14 weeks of age had inadequate antibody titers at 17 weeks of age. Kittens may be vaccinated in the perioperative period when necessary, and the primary vaccination series should be extended through at least 16 weeks of age.
OBJECTIVE To estimate seroprevalences for FeLV antigen and anti-FIV antibody and risk factors for seropositivity among cats in the United States and Canada.
DESIGN Cross-sectional study.
ANIMALS 62,301 cats tested at 1,396 veterinary clinics (n = 45,406) and 127 animal shelters (16,895).
PROCEDURES Blood samples were tested with a point-of-care ELISA for FeLV antigen and anti-FIV antibody. Seroprevalence was estimated, and risk factors for seropositivity were evaluated with bivariate and multivariable mixed-model logistic regression analyses adjusted for within-clinic or within-shelter dependencies.
RESULTS Overall, seroprevalence was 3.1% for FeLV antigen and 3.6% for anti-FIV antibody. Adult age, outdoor access, clinical disease, and being a sexually intact male were risk factors for seropositivity for each virus. Odds of seropositivity for each virus were greater for cats tested in clinics than for those tested in shelters. Of 1,611 cats with oral disease, 76 (4.7%) and 157 (9.7%) were seropositive for FeLV and FIV, respectively. Of 4,835 cats with respiratory disease, 385 (8.0%) were seropositive for FeLV and 308 (6.4%) were seropositive for FIV. Of 1,983 cats with abscesses or bite wounds, 110 (5.5%) and 247 (12.5%) were seropositive for FeLV and FIV, respectively. Overall, 2,368 of 17,041 (13.9%) unhealthy cats were seropositive for either or both viruses, compared with 1,621 of 45,260 (3.6%) healthy cats.
CONCLUSIONS AND CLINICAL RELEVANCE Seroprevalences for FeLV antigen and anti-FIV antibody were similar to those reported in previous studies over the past decade. Taken together, these results indicated a need to improve compliance with existing guidelines for management of feline retroviruses.