ABSTRACT
A 1.5-year-old American quarter horse gelding (case 1) and an 11-month-old American quarter horse filly (case 2) were presented for acute onset pelvic lameness and lethargy. Case 1 had nasal discharge, while case 2 developed rapid muscle atrophy. Both horses had elevated serum creatine kinase activity. The horses showed similar polyphasic histiocytic and lymphoplasmacytic myositis with necrosis, mineralization, and regeneration. Additionally, case 1 had Streptococcus equi subsp. equi-induced suppurative retropharyngeal lymphadenitis with renal purpura hemorrhagica and myoglobinuric nephropathy. A focal pulmonary abscess caused by Actinobacillus equuli was found in case 2. Genetic testing revealed case 1 as heterozygous and case 2 as homozygous for the E321G MYH1 variant, supporting the diagnosis of myosin heavy-chain myopathy, with concomitant bacterial disease as potential triggers.
ABSTRACT
American trypanosomiasis is caused by the zoonotic protozoa Trypanosoma cruzi and primarily results in heart disease. Organisms also infect the central nervous system (CNS). The Texas A&M University veterinary teaching hospital archive was searched for dogs with CNS disease with intralesional protozoal amastigotes. This study summarizes 4 cases of dogs with disseminated trypanosomiasis and CNS involvement confirmed by quantitative polymerase chain reaction (qPCR) with T. cruzi primers. Clinical signs included lethargy, respiratory distress, tetraparesis, and seizures. Central nervous system lesions included meningeal congestion (1/4), necrosis with hemorrhage in the spinal cord gray and white matter (2/4), and histiocytic meningoencephalitis (4/4), and meningomyelitis (2/4) with intralesional and intracellular protozoal. Genotyping identified 1 case of T. cruzi discrete typing unit (DTU) TcI and 2 cases as TcIV, both are common variants in the United States. Trypanosomiasis should be considered a differential diagnosis for dogs with CNS signs in T. cruzi-endemic areas.
