Systemic Toxoplasmosis in a Horse

An adult American Quarter Horse gelding with a history of weight loss presented with an acute onset of colic, fever, soft faeces and elevated liver enzymes. At necropsy, there were gastric mucosal masses and evidence of caecal necrosis. Histologically, the masses were lymph nodes with granulomatous inflammation and areas of liquefactive necrosis. Within and surrounding necrotic areas were free and intrahistiocytic clusters of protozoal tachyzoites. Similar but milder inflammation was evident in the spleen, lungs and liver. Necrotizing typhlitis was also evident. Immunolabelling for Toxoplasma gondii was positive and the ultrastructural morphology of the protozoa was compatible with T. gondii. Although studies have shown seropositivity to T. gondii in horses throughout the world, this is the first report of clinical toxoplasmosis in this species. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

An adult American Quarter Horse gelding with clinical toxoplasmosis presented with acute colic, fever, soft faeces and elevated liver enzymes. Necropsy revealed gastric mucosal masses, evidence of caecal necrosis, and histological examination showed lymph nodes with protozoal tachyzoites.