Today’s case is a 3-year-old male neutered Siamese cross with weight loss, lethargy, and anorexia. What is your diagnosis?
The cardiac silhouette is mildly enlarged, and the pulmonary vessels appear normal. There is a diffuse nodular interstitial pulmonary pattern throughout the lungs. The lung lobes are mildly retracted with pleural fissure lines visible. Within the portion of the abdomen included, there is poor serosal detail. There are small gas bubbles present in the cranial thoracic esophagus. The animal is in thin body condition.
Differential diagnoses for the pulmonary pattern and mild pleural effusion include inflammatory granulomatous disease, such as FIP or fungal pneumonia, or less likely neoplasia. The poor serosal detail is likely due to a combination of lack of fat and peritoneal effusion. Abdominal ultrasound is recommended to investigate the abdomen.
Abdominal ultrasound showed mild peritoneal effusion and lymphadenopathy.
Necropsy – FIP with severe lymphocytic plasmacytic pneumonia and fibrosis in the lungs. The abdomen was affected with granulomatous peritonitis.
The image is of multifocal histiocytic neutrophilic inflammation within the pulmonary parenchyma along with fibrosis and type 2 pneumocyte hyperplasia and vasculitis. In one image there are inflammatory nodules along with the histiocytic inflammation and fibrosis of the pleura and mesothelial cell hyperplasia. We performed an IHC for feline corona virus which had positive brown staining cells.