Naturally occurring tumours in domestic animals have been recognized as an interesting opportunity for comparative oncology (MacEwen, 1990; Vail & MacEwen, 2000). Cancer is the second most frequent cause of death in humans and the first one in dogs and cats (Jemal et al. 2003). The age-adjusted overall cancer incidence per 100000 individuals per year is comparable in humans and domestic animals, being approximately 300 in humans, 381 in dogs and 264 in cats (Vail & MacEwen, 2000). When analysing the incidence by site, breast cancer is the most frequent (32%) in women, the first of all neoplasia (52%) occurring in bitches and the third (17%) in queens after lymphohaemopoietic and skin tumours (Hayes et al. 1981; Hayes & Mooney, 1985; MacEwen, 1990; MacEwen & Withrow, 1996; Jemal et al. 2003). Several other aspects contribute to the value of domestic animals as models for human cancers (MacEwen, 1990; Vail & MacEwen, 2000). Tumours occur spontaneously in companion animals that share a similar environment with humans and therefore might be exposed to similar risk factors. The high incidence of some tumour types offers large population samples. The shorter overall lifespan of domestic animals associated with a more rapid progression of cancer allows adequate comparison of response time with humans. Biological, anatomical, histopathological, genetic, and molecular similarities between some animal and human tumours are also well established (Hansen & Khanna, 2004). Finally, testing novel therapies is more ethically acceptable when treating spontaneous diseases in companion animals rather than experimentally induced pathologies in animal models. At the same time, there is an increasing interest of owners towards the use of the most advanced therapeutic tools for companion animals despite the higher economic costs associated with these therapies.

The illegal trade of animals poses several health issues to the global community, among which are the underestimated risk for spillover infection and the potential for an epizootic in both wildlife and domestic naïve populations. We herein describe the genetic and antigenic characterization of viruses of the specie Carnivore protoparvovirus 1 detected at high prevalence in puppies illegally introduced in North Eastern Italy and compared them with those circulating in wild carnivores from the same area. We found evidence of a wide diversity of canine parvoviruses (CPV-2) belonging to different antigenic types in illegally imported pups. In wildlife, we found a high circulation of feline parvovirus (FPV) in golden jackals and badgers, whereas CPV-2 was observed in one wolf only. Although supporting a possible spillover event, the low representation of wolf samples in the present study prevented us from inferring the origin, prevalence and viral diversity of the viruses circulating in this species. Therefore, we suggest performing more thorough investigations before excluding endemic CPV-2 circulation in this species.

Concurrent leishmaniasis and neoplasia has been reported in dogs. This study describes the presence of the protozoa within the cytoplasm of neoplastic cells in 3 different types of tumors. Leishmania amastigotes were detected by light and transmission electron microscopy and immunohistochemistry in a fibrosarcoma, a T-cell lymphoma, and an adrenocortical adenoma.

A gastric lymphoid tumor with involvement of regional lymph nodes and spleen was diagnosed in an 8-year-old crossbreed male dog with a 6-month history of gastrointestinal disease. Despite surgical excision and palliative therapy (prednisolone and cimetidine), the dog was euthanized due to worsening of clinical signs. At necropsy, multiple white, solid, nodular, infiltrative masses were observed in the stomach, duodenum, spleen, liver, and lungs in association with generalized lymph node enlargement. Cytology, histology, histochemistry, immunohistochemistry, and electron microscopy revealed that the neoplastic cell population was composed of B lymphocytes that contained variable amounts of round periodic acid-Schiff-positive cytoplasmic globules consistent with Russell bodies. The tumor most likely represented a variant of B-cell neoplasia with extensive Mott cell differentiation.

Leptospirosis is one of the most widespread zoonotic diseases and can infect both humans and animals worldwide. The role of the cat as a susceptible host and potential environmental reservoir of Leptospira is still not well understood, due to the lack of obvious clinical signs associated with Leptospira spp. infection in this species. This study aims to describe the first European detection of Leptospira interrogans serogroup Australis ST 24 in a young outdoor cat with a severe comorbidity (feline panleukopenia virus). In addition, the results of a preliminary study conducted in 2014–2016 are presented (RC IZSVE 16/12), which reports an investigation of Leptospira exposure of outdoor cats in Northeast Italy by means of serological investigation and molecular evaluation of urine. The animals included in the survey are part of samples collected during active and passive surveillance (diagnostic samples). The study reported a seroprevalence of 10.5% among outdoor cats and the serogroups identified were Grippotyphosa, Icterohaemorrhagiae, Bratislava, Canicola and Ballum. Symptomatic cats reported high MAT titres (ranging from 1:800 to 1:1600) towards antigens belonging to the serovars Grippotyphosa (1:800), Bratislava (1:1600), Icterohaemorrhagiae (1:200) and Copenhageni (1:200–1:800). In one subject, urine tested positive for Leptospira PCR. Cats with high antibody titres for Leptospira and/or positivity on molecular test suffered from immunosuppressive comorbidities (feline immunodeficiency virus and feline leukaemia virus; feline herpesvirus and lymphoma; hyperthyroidism). The overall prevalence of serum antibodies against Leptospira found in free-ranging cats (10.53%, 95% CI: 4.35–16.70%) and the identification of L. interrogans ST 24 in a young cat with immunosuppressive disease (feline panleukopenia virus) suggest the possibility of natural resistance to clinical leptospirosis in healthy cats. In a One Health perspective, further studies are needed to better define the pathogenesis of leptospirosis in cats and their epidemiological role as environmental sentinels or possible carriers of pathogenic Leptospira.