Feline Leukaemia Virus Associated with Leukaemia in Cats in Santa Catarina, Brazil

Leukaemia is a haemopoietic neoplasm originating from myeloid or lymphoid precursors in the bone marrow and may be either acute or chronic. These tumours are rare, but occur more frequently in cats because of an association with the feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV). To the best of our knowledge, no studies conducted in Brazil to date have analysed the association between leukaemia and FeLV and FIV infection in cats. The aim of this study was to perform a histopathological analysis of feline leukaemia and evaluate the association between leukaemia and FeLV and FIV infection in cats. The study evaluated 37 cats with leukaemia diagnosed between 2009 and 2017. The animals underwent necropsy examination, histopathology and immunohistochemistry with anti-FeLV gp70 and anti-FIV p24 gag antibodies. Of the evaluated animals, 54% (20/37) were males and 43.2% (16/37) were females. With respect to the life stage of the animals, 24.3% (9/37) were junior, 32.4% (12/37) were prime, 18.9% (7/37) were mature and 10.8% (4/37) were senior, and five animals were of unknown age. Myeloid leukaemia occurred in 56.8% (21/37) of the cases and lymphocytic leukaemia occurred in 43.2% (16/37) of the cases. Acute leukaemia (73%, 27/37) was more common than chronic leukaemia (27%, 10/37). The positivity for FeLV (78.4%, 29/37) and FIV (16.2%, 6/37) indicated a high association between FeLV infection and tumour development in the study region.

Feline Lymphoma and a High Correlation with Feline Leukaemia Virus Infection in Brazil

Lymphoma is the most important haemopoietic tumour in cats and has been associated with feline leukaemia virus (FeLV) infection. In Brazil, no studies have established a correlation between FeLV infection and lymphoma. The aim of this study was to characterize lymphomas arising in cats in Brazil anatomically and microscopically, and to correlate these data with FeLV infection as determined by immunohistochemistry for the FeLV gp70 antigen. Fifty-three cats with lymphoma were evaluated. The mean age of junior, prime, mature, senior and geriatric cats was 1.65 years, 4.34 years, 8 years, 12.14 years and 15.5 years, respectively. The anatomical types of lymphoma were multicentric (43.4%, 23/53), mediastinal (33.96%, 18/53), renal (11.32%, 6/53), hepatic (5.66%, 3/53), nodal (3.77%, 2/53) and alimentary (1.89 %, 1/53). The histological types were small noncleaved-cell (33.96%, 18/53), mixed diffuse (22.64%, 12/53), immunoblastic (15.11%, 8/53), lymphoblastic (11, 32%, 6/53), small lymphocytic (9.43%, 5/53), small cleaved-cell (3.77%, 2/53) and large cell lymphomas (3.77%, 2/3). Immunopositivity for FeLV was observed in 56.6% (30/53) of the samples. FeLV positivity was equally distributed between the genders, but predominated in junior and prime cats. The degree of association between lymphoma and FeLV infection in Brazil was higher than that found in other countries, demonstrating the need to prevent and control the factors associated with infection.