Prevalencia y caracterización clínico-lesional de los principales procesos infecciosos de etiología vírica que afectan a las colonias de gatos callejeros en Madrid capital

Abstract

In developed countries, there is a general concern about animal welfare, especially in pets. About 75% of domestic cats around the world live in the street, where infectious diseases are widespread, since they are not sanitary controlled. In Madrid, as in other cities, there are cat colonies in several locations with an increasing social and sanitary sensitivity to this type of animals. In the late years, this interest has been reflected in the creation of animal protection societies that are involved in taking care of cats from these colonies, allowing the direct access to the cats for their sanitary examination and control. Moreover, the veterinary clinical activity specialized in feline species has significantly increased. For infectious disease diagnosis, in the recent years, new sensitive, specific and affordable diagnostic tools have been developed and have allowed the direct and rapid diagnosis of a wide range of diseases in the clinic. Considering the scarcity of studies on the sanitary status of cats coming from street colonies and under the hypothesis that viral diseases would be spread in those communities, causing severe clinical signs affecting animal welfare and allowing their dissemination, the main objective of this study was to establish the prevalence of the main viral infectious diseases affecting the cats in street cats from Madrid. Moreover, the diffusion of these infections among the different locations and the relationship with the age, sex and main clinical signs and lesions found, were also analyzed. A total of 296 street cats, from four colonies located in Madrid, were examined. The cats were captured in close collaboration with animal protection associations. They were coming from four cat colonies located in Entrevías, (n=54), Vallecas (n=54), Buen Retiro park (n=76) y Sacramental cemetery (n=112). A total of 133 (44.93%) cats were females and 163 (55.07%) males. Age was determined by dental examination and cats were classsified as younger than 5 months (118; 39.86%) and adults, between 5 months and 4-5 years (178; 60.14%). Animals were homogeneously distributed according to sex and age among the four colonies examined. Blood samples, for serum obtaining, and fecal samples with a fecal swab, were taken. Serum samples were used for antibody determination against feline immunodeficiency virus (FIV) and leukemia virus (FeLV) while fecal samples were employed for panleukopenia virus (VPF) and coronavirus (FCoV) antigen detection. Rapid diagnostic techniques, available as commercial kits, were used. Moreover, herpesvirus/calicivirus infection was determined by the examination of the presence of clinical signs and lesions related to these viruses. More precisely, the existence of rhinotracheitis, blepharoconjunctivitis and corneal ulcers, or gingivostomatitis were assessed. As both virus can be involved in the same type of lesion, the differentiation between both agents were not carried out, and animals were classified as compatible with infection by herpesvirus, coronavirus or both. From the 296 examined cats, 192 animals (64,86%) showed signs of being infected by any of the virus considered. The most prevalent infection was that associated with herpesvirus/calicivirus, since clinical signs and lesions were seen in 152 cats (51.35%), followed by the infection by FIV (19 animals; 6.42%), FeLV (13 cats 4.39%), VPF (16 animals; 5.41%) and FCoV (7 gatos; 2.36%). In the latter four viruses, since the specificity and sensitivity values of the diagnostic techniques were known, the true prevalence was calculated: 5,89% for FIV, 2.68% for FeLV, 3.51 for VPF and 0.28% for FCoV. The five infections were detected in cats coming from the four street colonies analyzed, without differences in the prevalence among them. Concerning the age, infections were most commonly found in adult cats (73.59%) than in young (51.69%), and regarding the viruses, a higher percentage of adult cats were seen in herpesvirus/coronavirus, FIV and FeLV infections, while infection due to FCoV was most frequently seenin young cats, without differences for VPF infection. About sex, no differences were seen for any of the infections. In 15 cases out of the 192 with lesions (7.81%), dual infections were demonstrated: two cats were positive for FIV and FeLV, eight for FIV and herpesvirus/calicivirus and the remaining 5 for the latter and FeLV. In relation to clinical signs, the percentage of animals that showed fever was significantly higher in infected cats (40.1%) than in those uninfected (14.42%). When the different viral agents were analyzed, although in all the cases the percentage of cats with fever was higher in the infected cats, differences were statistically significant in infections by VPD and FCoV. In cats infected by herpesvirus/coronavirus, the most frequently found lesions were rhinotracheitis (93.41%), gingivostomatitis (28.95%) or blepharoconjunctivitis (22.37%), that in a high percentage of animals were associated. An outstanding finding was the diagnosis of “feline odontoclastic resorptive lesion” (FORL), always associated with gingovostomatitis. The majority of cats infected by FIV and FeLV were asymptomatic and in two cases neoplastic diseases were diagnosed, a renal lymphoma in a cat infected by FeLV and a fibrosarcoma in an animal positive to FIV. In cats infected by VPF and FCoV, diarrhea and fever were the most consistently found clinical signs. In the group of uninfected cats, diarrhea was seen in a 34% of animals and dermatophitosis in a 26%. The latter was also diagnosed in cats infected by FIV, FeLV or VPF, possibly associated with the immunosuppression induced by these viruses. The results of this study point out that viral infections are highly prevalent among cats that live in street colonies in Madrid. These infections are associated with evident clinical signs that can be severe in some cases and that directly have an impact on animal welfare. Moreover, they pose a risk for contagion to the rest of the cats. These results would support the necessity of the establishment of sanitary control programs in this type of animals.