Cytological evaluation of cerebrospinal fluid in a dog infected with toxoplasmosis and distemper – Case Report

Resumo

Toxoplasmosis is a zoonotic disease caused by the protozoan Toxoplasma gondii, which affects various species. Dogs are intermediate hosts and, due to their role as sentinel animals, help monitor the environmental condition. The infection is more common in cases of immunosuppression and coinfection, and infected dogs are usually asymptomatic. Although rare, the infection, when associated with distemper, significantly increases the severity of neurological symptoms. In the present case, a four-year-old male Golden Retriever dog was treated for symptoms including apathy, anorexia, cachexia, vomiting, and abdominal pain upon palpation. In addition to nonspecific symptoms, the dog exhibited severe neurological symptoms. The first complete blood count revealed intense pancytopenia, and the second showed worsening with intense normocytic normochromic non-regenerative anemia, as well as severe leukopenia and thrombocytopenia. Elevated ALT and urea levels were also observed. Due to the severely debilitated condition, the animal died. Immediately after death, cerebrospinal fluid (CSF) was collected for analysis. The sample was xanthochromic, turbid, and exhibited intense pleocytosis, with 156 mg/dL of proteins, a density of 1.016, and a pH of 6.5. Cytoscopy revealed a predominance of mononuclear cells, mainly reactive lymphocytes and heavily activated, foamy macrophages, with the presence of erythrophagocytosis and leukophagocytosis. The neutrophils present were degenerated. Additionally, Toxoplasma sp. bradyzoites were observed, both phagocytized and free in the background, as well as Lentz bodies exclusively intracellularly. The report concludes that canine toxoplasmosis, associated with immunosuppressive diseases like distemper, causes severe neurological symptoms, often confused with other diseases, which can delay diagnosis and lead to death. Therefore, toxoplasmosis should be considered an important differential diagnosis. CSF examination is crucial in cases of severe neurological symptoms, especially when previous treatments have failed, as it was essential for the diagnosis guidance in this case.