C. J. Gaskell

A Study of Feline Upper Respiratory Tract Disease with Reference to Prevalence and Risk Factors for Infection with Feline Calicivirus and Feline Herpesvirus

A cross-sectional survey of a convenience sample of cats was carried out to determine the prevalence of and risk factors for respiratory tract disease, feline calicivirus (FCV) infection and feline herpesvirus (FHV) infection. Seven hundred and forty cats were studied; samples for isolation of FCV and FHV were obtained from 622 (84%). Data on individual cat and household variables were obtained by questionnaire for each cat and analysed using univariable and logistic regression analysis. Thirty-eight percent (282/740) of cats surveyed had respiratory tract disease. Eighteen of 24 predictor variables were found to be significantly (P<0.05) associated with the presence of respiratory tract disease in a cat on univariable analysis. Following logistic regression, several factors retained significance including isolation of FCV and FHV, younger cats (4–11 months of age) and multiple cat households. A negative association was found with breeding catteries and other types of household in comparison with rescue catteries. Overall, feline calicivirus was isolated from 162/622 (26%) of cats sampled; 33% of the cats with respiratory tract disease were FCV positive compared to 21% of healthy cats. Variables significantly associated with FCV isolation on logistic regression were the presence of respiratory tract disease and contact with dogs with and without respiratory tract disease. Feline herpesvirus was isolated from 30/622 (5%) of all cats sampled; 11% of cats with respiratory tract disease were FHV positive compared to 1% of healthy cats. Variables significantly associated with FHV isolation on univariable analysis included age, gender, and the presence of respiratory tract disease. Vaccination showed a negative association. Logistic regression analysis of the data for FHV was limited by the sample size and the low prevalence of FHV.

Studies on the role of feline calicivirus in chronic stomatitis in cats

Two groups of cats were inoculated oro-nasally with one of two isolates of feline calicivirus (FCV) from clinical cases of chronic stomatitis. All cats developed signs typical of acute FCV infection; namely, ocular and nasal discharge, conjunctivitis, and marked oral ulceration. None of the cats shed virus beyond 28 days. Seronegative control cats were then infected with a lower dose of one isolate, but again only acute signs were seen and no carriers produced. The original cats were then re-infected with the heterologous isolate. As before, only signs of acute disease were seen, but the range of clinical signs and severity was reduced. Virus shedding patterns in one group were similar to those seen originally, but in the other the duration was reduced. No chronic stomatitis developed over the 10 months of the study. Serum virus neutralising and serum and salivary class specific immunoglobulin responses were investigated. Although long-term carriers were not induced, no relationship between cessation of virus shedding in an individual animal and systemic and local antibody responses was seen.

Studies on poxvirus infection in cats.

SummaryThe development of clinical disease and the pathogenesis of cowpox were studied in domestic cats inoculated by a variety of routes. Intradermal titration in two cats demonstrated that as little as five pfu of cowpox virus caused a primary skin lesion. Intradermal inoculation of ⩾105 pfu cowpox virus resulted in severe systemic disease. Large amounts of virus (⩾103 pfu/g) were isolated from skin lesions and the turbinates of cats killed at eight and 11 days post-inoculation (dpi). Lesser amounts of virus (≃102 pfu/g) were isolated from lymphoid tissues and the lung, and small amounts of virus were isolated from various other tissues. A white cell-associated viraemia was detected from 5 dpi onwards. Skin scarification with 103 or 50 pfu cowpox virus enabled reproduction of the naturally-acquired disease. Cat-to-cat transmission was demonstrated from cats inoculated by skin scarification, but caused only subclinical infection in sentinel cats. Oronasal inoculation resulted in transient coryza and milder generalized disease than skin inoculation, and no transmission to sentinel cats. Preliminary investigations showed vaccinia virus (Lister strain) to be of low infectivity in cats while inoculation of ectromelia virus (Mill Hill strain) did not cause any clinical signs.

Canine coronavirus infection in the dog following oronasal inoculation

Abstract The pathogenesis of canine coronavirus (CCV) infection in 10-week-old puppies was studied up to 14 days after oronasal inoculation. Mild diarrhoea was seen from three to 11 days after inoculation, approximately coincident with faecal virus shedding. Virus was initially isolated from the tonsils on day 3, and then from both small and large intestinal tissues up to 14 days after inoculation. Virus was also isolated from liver and lung. Histological changes were not seen in any tissues, but CCV antigen was detected, using a peroxidase antiperoxidase staining technique, mainly in epithelium overlying gut-associated lymphoid tissue. Virus neutralising antibody was first detected on day 10. Specific anti-CCV IgM was first detected in plasma three days after inoculation and IgG on days 4 to 7. Small amounts of anti-CCV IgG, IgM and IgA were detected in duodenal secretion, but none in bile.

Prevalence and risk factors for feline Bordetella bronchiseptica infection

A cross-sectional survey of a convenience-sample of 740 cats was undertaken to obtain an estimate of the prevalence of Bordetella bronchiseptica infection, and to identify risk factors that might predispose them to the infection. Data on individual cats and household variables, including disease status and animal contacts were obtained by questionnaire. B bronchiseptica was isolated from 82 (11 per cent) of the cats sampled. The prevalence of B bronchiseptica varied with the type of household sampled, being 19.5 per cent in rescue catteries, 9 per cent in breeding catteries, 13.5 per cent in research colonies, and 0 per cent in household pets. On the basis of a univariable analysis, 19 of 29 predictor variables were found to be significantly associated with the isolation of B bronchiseptica, including an association with cats in rescue catteries, and with cats from premises with larger numbers of animals. Separate analysis of the rescue cattery subpopulation showed a highly significant association on multivariable analysis with current respiratory disease, suggesting that different risk fadors may operate in this type of environment. In the whole sample there was also a strong association with cats from households containing a dog with recent respiratory tract disease. The clinical signs observed in the B bronchiseptica-positive cats included sneezing, ocular and nasal discharges and coughing, although only the association with sneezing was statistically significant. There was no significant association between the isolation of B bronchiseptica and the isolation of respiratory viruses, suggesting that in some circumstances B bronchiseptica may be able to cause disease independently.

Studies on natural transmission of Bordetella bronchiseptica in cats

Two pregnant specific-pathogen-free (SPF) cats, from a colony endemically infected with Bordetella bronchiseptica, were housed under barrier conditions in the latter stages of pregnancy in order to study the possible transmission of the organism to their kittens. Both queens had antibody titres to Bordetella bronchiseptica of 1 in 320 at the start of the experiment but did not shed Bordetella bronchiseptica until 9 days and 6 weeks after parturition, respectively. Five of the nine kittens had detectable maternally-derived-antibody to Bordetella bronchiseptica which declined to ≤ 1 in 40 by two weeks of age. Kittens were weaned at 12 weeks of age. No Bordetella bronchiseptica was isolated from any of the kittens and none seroconverted over this time. At 15 12 weeks of age, half of each litter were housed separately and inoculated intra-nasally with 108 colony-forming-units B. bronchiseptica. Mild signs of upper respiratory tract disease were seen and the organism was isolated for 19 weeks following inoculation when the experiment ended. Seroconversion occurrred at 4 weeks post-inoculation. Oral treatment of two clinically-recovered kittens with doxycycline once a day did not eliminate shedding.

Effect of primary-stage feline immunodeficiency virus infection on subsequent feline calicivirus vaccination and challenge in cats

The effect of experimental primary-stage feline immunodeficiency virus (FIV) infection on feline calicivirus (FCV) vaccination and challenge in cats was studied. Clinical signs of acute FCV disease were more widespread in the cats which were infected with FIV than in those which were not. FIV infection also prolonged shedding of FCV, with more of the FIV-infected cats becoming chronic carriers. Although vaccination induced protection against acute FCV disease, this was to a lesser degree in FIV-infected cats. Vaccination by itself also appeared to enhance long-term virus shedding. There was evidence of an impaired anamnestic FCV-neutralizing antibody response in FIV-infected cats following FCV challenge.

Prevalence of feline chronic gingivo-stomatitis in first opinion veterinary practice

Feline chronic gingivo-stomatitis (FCGS) is a syndrome characterised by persistent, often severe, inflammation of the oral mucosa. In the absence of similar studies, our objective was to estimate the prevalence of FCGS in a convenience based sample of cats visiting first opinion small animal veterinary practices. Twelve practices took part, providing a sample population of 4858 cats. Veterinary surgeons identified cases of FCGS according to our case definition over a 12-week sampling period; age, sex and breed information was determined for all cats, plus brief descriptive data for FCGS cases. The prevalence of FCGS was 0.7% (34 cases, 95% confidence intervals: 0.5–1.0%). Of the 34 cases of FCGS, 44% (15 cats) were new cases and 56% (19 cats) were ongoing cases. No statistically significant difference (P>0.353) was found when the age, sex and breed of cats with FCGS were compared to data from cats without the condition.

Characterization of orthopoxviruses isolated from feline infections in Britain

SummaryThe biological properties and genomes of orthopoxviruses isolated from cats in Britain were compared with strains of cowpox virus isolated from cows and their handlers.All the isolates tested produced haemorrhagic pocks and A-type inclusions on the CAM, but did not produce pocks above 40°C. Thus the feline isolates behaved as typical strains of cowpox virus. Differences were found in the heat resistance of the virions and in the character of the A-type inclusion which did not correlate with the host from which the viruses were isolated. Analysis of the genomes with a variety of restriction endonucleases showed very close relationship between all the isolates and also failed to separate feline isolates from cowpox virus. However again minor differences, which may prove to be of epidemiological value were detected.We conclude that the orthopoxvirus currently isolated from domestic cats in Britain is cowpox virus and that there is no evidence that a feline variant or subspecies circulates in Britain.

Characterization of Cauxin in the Urine of Domestic and Big Cats

Cauxin is an abundant protein in feline urine. We have used proteomics strategies to characterize cauxin from the urine of domestic cats and a number of big cat species. Proteins were resolved by gel-based electrophoretic purification and subjected to in-gel digestion with trypsin. The resultant tryptic peptides were mass-measured by matrix-assisted laser desorption ionization time of flight mass spectrometry. Peptides were also resolved by liquid chromatography and analyzed by electrospray ionization and tandem mass spectrometry to generate fragment ion data to infer the amino acid sequence. We identified cauxin polymorphisms and corrected a sequencing artifact in cauxin from the domestic cat. The proteomics data also provided positive evidence for the presence of a cauxin homolog in the urine of big cats (Pantherinae), including the Sumatran tiger, Asiatic lion, clouded leopard, Persian leopard, and jaguar. The levels of cauxin in the urine of all big cats were substantially lower than that in the urine of intact male domestic cats.