Mitral valve bacterial endocarditis in a dog

A four year old male Spitz dog was presented with approximately a month old history of progressive depression, inappetance and lethargy. Clinically investigation showed leukocytosis, neutrophilia and monocytosis. Rectal temperature was 103°F, both rate and effort of respiration were increased. Heart rate was 110 b. p. m. with a bounding pulse and an audible cardiac murmur over the left heart base. The animal collapsed the next day and a necropsy examination was carried out. Large vegetations approximately 1 centimeter across extending from the mitral valve into the left atrial mural endocardium was observed together with a large embolic fragment about 0.5 centimeter in length in the left ventricular chamber. The lungs appeared congested and infarcts were observed on the spleen and kidneys. Urinalysis at post-mortem showed mild proteinuria. Histologically, the vegetation was composed of an irregular, amorphous thrombo-necrotic mass embedded with colonies of gram positive beaded filamentous bacteria. Micrometry of bacterial filaments ranged from 21.3 - 85.2 micrometer in length. Although, bacterial isolation was not carried out, the morphological and staining characteristics were indistinguishable from Erysipelothrix sp. Cause of death was attributed to severe left cardiac failure.