Seroprevalences of feline leukemia virus and feline immunodeficiency virus infection in cats in the United States and Canada and risk factors for seropositivity.

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.

Seroprevalence of heartworm infection, risk factors for seropositivity, and frequency of prescribing heartworm preventives for cats in the United States and Canada.

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.

Comparison of non-contact infrared thermometry and rectal thermometry in cats.

OBJECTIVES: Body temperature is commonly used for assessing health and identifying infectious diseases in cats. Rectal thermometry, the most commonly used method, is stressful, invasive and time consuming. Non-contact infrared thermometry (NIRT) has been used with mixed success to measure temperature in humans and other species. The purpose of this study was to determine if NIRT measurements were comparable to rectal temperature measurements or, if not highly correlated, could at least identify cats in the hypothermic or hyperthermic range in need of further evaluation. METHODS: From a total of six NIRT devices and 15 anatomic sites, three devices and three sites (pinna, gingiva and perineum) with the highest correlation to rectal temperature were selected for further study. Measurements were made in 188 adult cats housed indoors at animal shelters, veterinary clinics and private homes across a wide range of body temperatures and compared with rectal temperatures. RESULTS: Bland-Altman analysis revealed poor agreement between NIRT and rectal thermometry. The mean NIRT measurements ranged from 0.7-1.3°C below the mean rectal measurements, but the effect was not consistent; NIRT measurements tended to exceed rectal measurements in hypothermic cats and fall below rectal measurements in normothermic and hyperthermic cats. CONCLUSIONS AND RELEVANCE: The accuracy of temperature measurements using NIRT devices is not reliable for clinical use in cats.

Reference interval for rectal temperature in healthy confined adult cats.

OBJECTIVES: Despite the common use of rectal temperature for assessing health and identifying infectious diseases in cats, there is little evidence to support frequently cited feline reference intervals for rectal temperature. Body temperature measurements are most commonly performed indoors in animal shelters and veterinary clinics. In these facilities, cats are often inactive and housed in small enclosures in a climate-controlled environment. The purpose of this study was to establish a new reference interval for rectal temperature in healthy confined adult cats. METHODS: Rectal temperatures were measured in 200 healthy adult indoor cats in animal shelters, veterinary clinics and private homes. The reference interval was established using the method of the Clinical and Laboratory Standards Institute. RESULTS: The reference interval for healthy adult cat rectal temperature was determined to range from 36.7°C (confidence interval [CI] = 36.6-36.8°C; 98.1°F [CI = 97.9-98.3°F]) at the lower limit to 38.9°C (CI = 38.8-39.1°C; 102.1°F [CI = 101.9-102.3°F]) at the upper limit. The ambient temperature ranged from 20.3-30.8°C (68.5-87.5°F). Rectal temperature was not significantly correlated with ambient temperature. CONCLUSIONS AND RELEVANCE: A range of 36.7-38.9°C (98.1-102.1°F) should be considered the new reference interval for healthy adult cats for rectal temperature measured indoors in climate-controlled conditions. This range is lower than commonly reported. Use of previously published ranges could lead to overdiagnosis of hypothermia or underdiagnosis of mild pyrexia.

Tail vaccination in cats: a pilot study.

Feline injection site sarcomas affect 1-10 cats per every 10,000 vaccinated and are associated with high mortality. Radical resection may be curative, but is often associated with prolonged recovery, disfigurement and loss of function when tumors occur at currently recommended injection sites. The objective of this study was to assess alternatives to currently recommended vaccination sites in terms of preference by oncology practitioners, ease of injection and serological responses. Surgical, radiation and medical oncology practitioners were surveyed regarding their preference for vaccination sites based on the ease of tumor resection. A six-point Likert scale was used to measure each cat's behavioral reaction to vaccination when injected subcutaneously in the distal hind limb or the distal tail. Serum collected before and 1-2 months after vaccination was tested for antibody titers against feline panleukopenia virus (FPV) and rabies virus (RV). The preferred sites for vaccination by 94 oncology practitioners were below the stifle (41%) and the tail (30%). There were no significant differences in the cats' behavioral reaction to vaccination below the stifle (n = 31) and in the distal tail (n = 29). Of the cats seronegative for FPV at the time of vaccination, 100% developed protective antibody titers (≥40) against FPV 1-2 months following vaccination. For cats seronegative for RV, all but one cat (tail vaccine) developed acceptable antibody titers (≥0.5 IU/ml) against RV. Tail vaccination was well tolerated and elicited similar serological responses to vaccination in the distal limbs.

Prevalence of serum antibody titers against feline panleukopenia virus, feline herpesvirus 1, and feline calicivirus in cats entering a Florida animal shelter.

OBJECTIVE: To determine the proportion of cats entering a Florida animal shelter with serum antibody titers against feline panleukopenia virus (FPV), feline herpesvirus 1 (FHV1), and feline calicivirus (FCV) and to identify factors associated with seropositivity. DESIGN: Cross-sectional study. ANIMALS: 347 cats admitted to a Florida animal shelter. PROCEDURES: Within 24 hours after admission to the animal shelter, blood samples were collected from all cats ≥ 8 weeks of age. Serum antibody titers against FPV were determined via a hemagglutination inhibition assay, and those against FHV1 and FCV were determined via virus neutralization assays. Age, sex, environment (urban or rural), source (stray or previously owned), evidence of previous caregiving, health status (healthy or not healthy), and outcome (adoption, transfer, return to owner, or euthanasia) were evaluated as potential factors associated with antibody seropositivity. RESULTS: Of 347 cats, 138 (39.8%), 38 (11.0%), and 127 (36.6%) had antibody titers ≥ 40, ≥ 8, and ≥ 32 (ie, seropositive) against FPV, FHV1, and FCV, respectively. Factors associated with seropositivity included being neutered, age ≥ 6 months, and being relinquished by an owner. On multivariable analysis, health status at shelter admission, environment, vaccination at shelter admission, and outcome were not associated with seropositivity. CONCLUSIONS AND CLINICAL RELEVANCE: Most cats were seronegative for antibodies against FPV, FHV1, and FCV at the time of admission to an animal shelter. These findings supported current guidelines that recommend vaccination of all cats immediately after admission to animal shelters, regardless of the source or physical condition.

Enteropathogens identified in cats entering a Florida animal shelter with normal feces or diarrhea.

OBJECTIVE: To determine the frequency of enteropathogens in cats entering an animal shelter with normal feces or diarrhea. DESIGN: Cross-sectional study. ANIMALS: 100 cats evaluated at an open-admission municipal animal shelter in Florida. PROCEDURES: Fecal samples collected within 24 hours after admission from 50 cats with normal feces and 50 cats with diarrhea were tested by fecal flotation, antigen testing, PCR assay, and electron microscopy for selected enteropathogens. RESULTS: 12 enteropathogens were identified. Cats with diarrhea were no more likely to be infected with ≥ 1 (84%) enteropathogens than were cats with normal feces (84%). Only feline coronavirus was significantly more prevalent in cats with diarrhea (58%) than in cats with normal feces (36%). Other enteropathogens identified in cats with and without diarrhea included Clostridium perfringens enterotoxin A (42% and 50%, respectively), Cryptosporidium spp (10% and 20%, respectively), Giardia spp (20% and 8%, respectively), Cystoisospora spp (14% and 10%, respectively), hookworms (10% and 18%, respectively), ascarids (6% and 16%, respectively), Salmonella spp (6% and 4%, respectively), astrovirus (8% and 2%, respectively), feline panleukopenia virus (4% and 4%, respectively), calicivirus (0% and 2%, respectively), and Spirometra spp (0% and 2%, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: In the present study, cats entered the shelter with a variety of enteropathogens, many of which are pathogenic or zoonotic. Most infections were not associated with diarrhea or any specific risk factors such as signalment, source, or body condition, making it difficult to predict which cats were most likely to be infected. It is not possible to test all shelter cats for all possible infections, so practical guidelines should be developed to treat routinely for the most common and important enteropathogens.

Enteropathogens identified in dogs entering a Florida animal shelter with normal feces or diarrhea.

OBJECTIVE: To determine the frequency of enteropathogens in dogs entering an animal shelter with normal feces or diarrhea. DESIGN: Cross-sectional study. ANIMALS: 100 dogs evaluated at an open-admission municipal animal shelter in Florida. PROCEDURES: Fecal samples were collected within 24 hours after admission from 50 dogs with normal feces and 50 dogs with diarrhea. Feces were tested by fecal flotation, antigen testing, PCR assay, and electron microscopy for selected enteropathogens. RESULTS: 13 enteropathogens were identified. Dogs with diarrhea were significantly more likely to be infected with ≥ 1 enteropathogens (96%) than were dogs with normal feces (78%). Only Clostridium perfringens enterotoxin A gene was significantly more common in dogs with diarrhea (64%) than in dogs with normal feces (40%). Other enteropathogens identified in dogs with and without diarrhea included hookworms (58% and 48%, respectively), Giardia spp (22% and 16%, respectively), canine enteric coronavirus (2% and 18%, respectively), whipworms (12% and 8%, respectively), Cryptosporidium spp (12% and 2%, respectively), ascarids (8% and 8%, respectively), Salmonella spp (2% and 6%, respectively), Cystoisospora spp (2% and 4%, respectively), canine distemper virus (8% and 0%, respectively), Dipylidium caninum (2% and 2%, respectively), canine parvovirus (2% and 2%, respectively), and rotavirus (2% and 0%, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Dogs entered the shelter with a variety of enteropathogens, many of which are pathogenic or zoonotic. Most infections were not associated with diarrhea or any specific dog characteristics, making it difficult to predict the risk of infection for individual animals. Guidelines for preventive measures and empirical treatments that are logistically and financially feasible for use in shelters should be developed for control of the most common and important enteropathogens.

Effects of maternally-derived antibodies on serologic responses to vaccination in kittens.

The optimal vaccination protocol to induce immunity in kittens with maternal antibodies is unknown. The objective of this study was to determine the effects of maternally-derived antibody (MDA) on serologic responses to vaccination in kittens. Vaccination with a modified live virus (MLV) product was more effective than an inactivated (IA) product at inducing protective antibody titers (PAT) against feline panleukopenia virus (FPV). IA vaccination against feline herpesvirus-1 (FHV) and feline calicivirus (FCV) was more effective in the presence of low MDA than high MDA. Among kittens with low MDA, MLV vaccination against FCV was more effective than IA vaccination. A total of 15%, 44% and 4% of kittens had insufficient titers against FPV, FHV and FCV, respectively, at 17 weeks of age. Serologic response to vaccination of kittens varies based on vaccination type and MDA level. In most situations, MLV vaccination should be utilized and protocols continued beyond 14 weeks of age to optimize response by all kittens.

Detection of protective antibody titers against feline panleukopenia virus, feline herpesvirus-1, and feline calicivirus in shelter cats using a point-of-care ELISA.

Serum antibody titers are a useful measurement of protection against infection (feline panleukopenia virus [FPV]) or clinical disease (feline herpesvirus-1 [FHV] and feline calicivirus [FCV]), and their determination has been recommended as part of disease outbreak management in animal shelters. The objective of this study was to determine the sensitivity, specificity, and inter-observer and inter-assay agreement of two semi-quantitative point-of-care assays for the detection of protective antibody titers (PAT) against FPV, FHV and FCV in shelter cats. Low sensitivity for FPV antibodies (28%) rendered a canine point-of-care assay inappropriate for use in cats. The feline point-of-care assay also had low sensitivity (49%) and low negative predictive value (74%) for FPV PAT detection, but was highly accurate in the assessment of FHV and FCV PAT. Improvements in accuracy and repeatability of FPV PAT determination could make this tool a valuable component of a disease outbreak response in animal shelters.

Long-term fertility control in female cats with GonaCon™, a GnRH immunocontraceptive.

The uncontrolled reproduction of free-roaming feral cats contributes to overpopulation and associated concerns regarding their welfare and impact on public health and the environment. Nonsurgical fertility control that could be administered to feral cats in the field would be a powerful tool for cat population control. The objective was to test the efficacy and duration of activity of a single-dose GnRH immunocontraceptive vaccine (GonaCon™) on the fertility of adult female laboratory cats. Vaccinated cats (n = 15) received a single injection of vaccine containing a GnRH-KLH conjugate (200 µg) emulsified in a mycobacterial and oil adjuvant on study Day 0. Sham-treated cats (n = 5) received a single injection containing all vaccine components except the GnRH-KLH conjugate. A breeding trial started on study Day 120. Vaccinated cats had a longer time to conception (median 39.7 mo) compared to sham-treated cats (4.4 mo; P < 0.001). A total of 93% of vaccinated cats remained infertile for the first year following vaccination, whereas 73, 53, and 40% were infertile for 2, 3, and 4 y, respectively. At study termination (5 y after a single GnRH vaccine was administered), four cats (27%) remained infertile. The GnRH antibody titers declined more rapidly in short-term responding cats with < 2 y of infertility (n = 4), compared to long-term responding cats that experienced fertility control for >2 y (n = 11) (P < 0.05). Non-painful but persistent late-onset granulomatous injection site masses appeared 2 y after initial vaccination in five cats. We concluded that GnRH immunocontraception is an ideal candidate for further development for feral cat control.

Association of Wolbachia with heartworm disease in cats and dogs.

Although the presence of adult Dirofilaria immitis in the pulmonary arteries and its associated arteritis and thromboembolic disease can explain some of the manifestations of canine and feline heartworm disease, the cause of other findings remains unclear. Cats with D. immitis antibodies but lacking adult parasites in the pulmonary arteries frequently develop histological lesions of the airways, resulting in a condition termed Heartworm-Associated Respiratory Disease. All D. immitis parasites harbor Wolbachia pipientis bacteria and D. immitis-infected animals can have circulating Wolbachia antibodies and pro-inflammatory Wolbachia antigens (WSP) deposited in tissues. Little is known about the role that Wolbachia plays in lung disease of animals naturally infected with D. immitis. The purpose of this study was to determine the contribution of Wolbachia to the pathogenesis of natural heartworm disease in cats and dogs. We hypothesized that animals having sufficient Wolbachia burden to be detected in lung tissue by immunohistochemistry and/or polymerase chain reaction (PCR) would have more severe pulmonary disease than those with bacteria below the limits of detection. We further hypothesized that animals that were immunoreactive to pro-inflammatory WSP would have more severe pulmonary lesions than those that were seronegative for WSP antibodies. Blood and lung tissue samples were collected from cats and dogs representing three different D. immitis infection statuses: heartworm-free, heartworm-exposed, heartworm-infected. There was a positive but weak correlation between the magnitude of D. immitis antibody titers and WSP titers in cats (r=0.57, p<0.001) and in dogs (r=0.39, p<0.001). Pulmonary lesions were more common in HW-infected animals than in HW-free animals. Pulmonary arteriolar occlusion was more common in HW-infected cats (57%; p=0.003) than in HW-infected dogs (17%). Although pulmonary lesions were most common in HW-infected animals, there was no clear additive effect when either Wolbachia DNA/WSP was detected in lung tissue or when circulating Wolbachia antibodies were detected. There were no significant differences in the magnitude of pulmonary lesion scores within each HW-infection status group regardless of whether Wolbachia DNA/WSP or antibodies were detected. The relationship between Wolbachia and lung pathology in heartworm-infected animals remains to be determined. The lack of clear evidence for a role of Wolbachia in heartworm disease creates a dilemma for veterinarians treating animals in D. immitis-endemic areas. Although the indiscriminant use of antibiotics should be avoided, many clinicians prescribe doxycycline based on the favorable responses observed in human filarial diseases and promising results from the first published studies of doxycycline use in D. immitis-infected dogs.

Effects of anesthesia and surgery on serologic responses to vaccination in kittens.

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.

Effect of vaccination on parvovirus antigen testing in kittens.

OBJECTIVE: To determine the frequency and duration of feline panleukopenia virus (FPV) vaccine-induced interference with fecal parvovirus diagnostic testing in cats. DESIGN: Prospective controlled study. ANIMALS: Sixty-four 8- to 10-week-old specific-pathogen-free kittens. PROCEDURES: Kittens were inoculated once with 1 of 8 commercial multivalent vaccines containing modified-live virus (MLV) or inactivated FPV by the SC or intranasal routes. Feces were tested for parvovirus antigen immediately prior to vaccination, then daily for 14 days with 3 tests designed for detection of canine parvovirus. Serum anti-FPV antibody titers were determined by use of hemagglutination inhibition prior to vaccination and 14 days later. RESULTS: All fecal parvovirus test results were negative prior to vaccination. After vaccination, 1 kitten had positive test results with test 1, 4 kittens had positive results with test 2, and 13 kittens had positive results with test 3. Only 1 kitten had positive results with all 3 tests, and only 2 of those tests were subjectively considered to have strongly positive results. At 14 days after vaccination, 31% of kittens receiving inactivated vaccines had protective FPV titers, whereas 85% of kittens receiving MLV vaccines had protective titers. CONCLUSIONS AND CLINICAL RELEVANCE: Animal shelter veterinarians should select fecal tests for parvovirus detection that have high sensitivity for FPV and low frequency of vaccine-related test interference. Positive parvovirus test results should be interpreted in light of clinical signs, vaccination history, and results of confirmatory testing. Despite the possibility of test interference, the benefit provided by universal MLV FPV vaccination of cats in high-risk environments such as shelters outweighs the impact on diagnostic test accuracy.

Response of feral cats to vaccination at the time of neutering.

OBJECTIVE: To determine whether administration of inactivated virus or modified-live virus (MLV) vaccines to feral cats at the time of neutering induces protective serum antiviral antibody titers. DESIGN: Prospective study. ANIMALS: 61 feral cats included in a trap-neuter-return program in Florida. PROCEDURES: Each cat received vaccines against feline panleukopenia virus (FPV), feline herpes virus (FHV), feline calicivirus (FCV), FeLV, and rabies virus (RV). Immediately on completion of surgery, vaccines that contained inactivated RV and FeLV antigens and either MLV or inactivated FPV, FHV, and FCV antigens were administered. Titers of antiviral antibodies (except those against FeLV) were assessed in serum samples obtained immediately prior to surgery and approximately 10 weeks later. RESULTS: Prior to vaccination, some of the cats had protective serum antibody titers against FPV (33%), FHV (21%), FCV (64%), and RV (3%). Following vaccination, the overall proportion of cats with protective serum antiviral antibody titers increased (FPV [90%], FHV [56%], FCV [93%], and RV [98%]). With the exception of the FHV vaccine, there were no differences in the proportions of cats protected with inactivated virus versus MLV vaccines. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that exposure to FPV, FHV, and FCV is common among feral cats and that a high proportion of cats are susceptible to RV infection. Feral cats appeared to have an excellent immune response following vaccination at the time of neutering. Incorporation of vaccination into trap-neuter-return programs is likely to protect the health of individual cats and possibly reduce the disease burden in the community.

Immunoglobulin concentrations in feline colostrum and milk, and the requirement of colostrum for passive transfer of immunity to neonatal kittens.

The purpose of this study was to clarify whether cats have a colostral and milk phase of lactation differentiated by concentrations of immunoglobulins, and whether colostrum ingestion by newborn kittens is essential for optimal transfer of passive immunity. Milk from specific pathogen-free queens was analyzed for IgG and IgA concentrations from parturition through 6 weeks of lactation. Serum IgG and IgA concentrations from birth through 8 weeks of age were determined for colostrum-fed kittens, colostrum-deprived kittens that were fed a milk replacer, and colostrum-deprived kittens that were fostered onto queens in the milk phase of lactation. The total IgG and IgA concentrations in milk were significantly higher on the day of parturition than on day 7 of lactation, indicating cats do have a colostral phase of lactation. The predominant immunoglobulin in both colostrum and milk was IgG. The serum IgG concentrations in colostrum-deprived kittens fostered on queens in the milk phase of lactation were similar to colostrum-deprived kittens fed a milk replacer, and the concentrations were significantly lower than in colostrum-fed kittens for the first 4 weeks of life. The serum IgA concentrations in both colostrum-deprived groups were significantly lower than colostrum-fed kittens on day 2 after parturition, but were similar thereafter. Colostrum-deprived kittens fostered onto queens in the milk phase of lactation had failure of passive transfer of maternal antibodies. Protective concentrations of immunoglobulins can be restored in kittens with failure of passive transfer of immunity by parenteral administration of adult cat serum, but not by fostering on queens in mid-lactation.

Validation and use of an indirect enzyme-linked immunosorbent assay for detection of antibodies to West Nile virus in American Alligators (Alligator mississippiensis) in Florida.

In October 2002, West Nile virus (WNV) was identified in farmed American alligators (Alligator mississippiensis) in Florida showing clinical signs and having microscopic lesions indicative of central nervous system disease. To perform seroepidemiologic studies, an indirect enzyme-linked immunosorbent assay (ELISA) was developed to determine exposure of captive and wild alligators to WNV. To validate the test, a group of WNV-seropositive and -seronegative alligators were identified at the affected farm using hemagglutination inhibition (HAI) and the plaque reduction neutralization test (PRNT). The indirect ELISA utilized a rabbit anti-alligator immunoglobulins polyclonal antibody as the secondary antibody, and inactivated WNV-infected Vero cells were used as the coating antigen. For all samples (n=58), the results of the ELISA were consistent with the HAI and PRNT findings. Plasma was collected from 669 free-ranging alligators from 21 sites across Florida in April and October 2003. Four samples collected in April and six in October were positive for WNV antibodies using HAI, PRNT, and the indirect ELISA. This indicated that wild alligators in Florida have been exposed to WNV. These findings can be used as a baseline for future surveys.

Effects of passive transfer of immunity on results of diagnostic tests for antibodies against feline immunodeficiency virus in kittens born to vaccinated queens.

OBJECTIVE: To determine whether passive transfer of immunity affects results of diagnostic tests for antibodies against FIV in kittens born to vaccinated queens. DESIGN: Experimental trial. ANIMALS: 12 specific-pathogen-free queens and their 55 kittens. PROCEDURE: Queens were vaccinated with a whole-virus FIV vaccine prior to breeding. Serum was obtained from the queens on the day of parturition and from the kittens on days 2 and 7, then weekly until results of tests for antibodies against FIV were negative for 2 consecutive weeks. Milk was collected from the queens daily for the first week and then weekly. Serum and milk were tested for antibodies against FIV with 2 commercial assays. RESULTS: Antibodies against FIV were detected in serum obtained from the queens on the day of parturition and in the milk throughout lactation. All kittens tested positive for antibodies against FIV at 2 days of age. At 8 weeks of age, 30 (55%) kittens tested positive with 1 of the commercial assays, and 35 (64%) tested positive with the other. All kittens tested negative for antibodies against FIV by 12 weeks of age. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that kittens readily absorb antibodies against FIV in colostrum from vaccinated queens and that these antibodies may interfere with results of commercially available tests for FIV infection past the age of weaning. Currently licensed diagnostic tests for FIV infection are unable to distinguish among kittens with antibodies against FIV as a result of infection, passive transfer from infected queens, and passive transfer from vaccinated queens.