Cat with many skin nodules caused by toxoplasmosis infection

Abstract

Abstract A 9‐year‐old female, domestic short hair cat was presented with sudden onset of polyuria/polydipsia, and hundreds of cutaneous nodules. Prior to referral, the cat had had four skin nodules that were treated with steroids. The four skin nodules then multiplied to form more than 100 ulcerated and nonulcerated nodules located all over the trunk. Clinical evaluation revealed hypothermia and respiratory distress. Cytology from both skin nodules and bronchoalveolar lavage showed macrophages and small organisms whose shape and size were indicative ofToxoplasmaspp., or similar organisms. Feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) serology results were negative. The cat was seropositive forToxoplasma(IgG 1 : 640) andNeospora(1 : 80) infections. The cat died soon after referral. Necropsy revealed pyothorax, necrotic/purulent pneumonia, haemorrhagic spots on kidneys and mesentery. Histopathology from skin nodules showed diffuse, deep necrotic dermatitis/panniculitis, vasculitis and disseminated free and grouped protozoa. The parasites were found in lungs, spleen, kidneys and liver. Immunohistochemistry on skin tissue with anti‐Toxoplasma gondiiandNeospora caninumantibodies gave positive results with both. Electron microscopy showed single and grouped tachyzoites with morphological features ofT. gondii, often within macrophages. Samples of cutaneous nodules and bronchoalveolar fluid were examined by a polymerase chain reaction (PCR) assay for detecting apicomplexa coccidia. PCR results were consistent only withT. gondiiinfection. Therefore, immunohistochemistry positivity forN. caninumwas considered a cross‐reaction and a diagnosis of cutaneous and visceral toxoplasmosis was made.