Examples of lesions observed in the esophagus in case #1 Case #1 — Severe oral and mucosal lesions associated with acute BVD infection
Bill Hessman, Haskell County Animal Hospital LLC, was called in to consult on a disease outbreak in the fall of 2008 in a northwest Texas feedlot. The high morbidity and mortality plus severity of lesions initially raised concerns about the presence of a new pathogen or the introduction of a foreign pathogen into the herd. Signs included fever and extensive ulcerative lesions of the larynx, trachea and esophagus. Two lots of heifers were involved in the outbreak. Of the 159 calves in lot A, 119 became ill and 45 died. Of the 45 mortalities, 22 had marked mucosal lesions. Losses were smaller in lot B, with 79 out of 160 animals sick and six dying. Three of the six dead animals had extensive mucosal lesions. The lesions observed were described in the Journal of Veterinary Diagnostic Investigation thusly:
“Grossly, the mucosal lesions observed on necropsy varied dramatically. Lesions were observed in the oral cavity on buccal surfaces and tongue, and in the larynx, trachea and esophagus. Small infrequent, 1-3 mm, irregular but sharp-edged ulcerations without gross necrotic material were observed in the esophagus of some animals but others had extensive, multifocal, 1mm to 1 cm, circular to ovoid mucosal ulcerations involving the majority of the esophagus with and without necrotic debris. Yet other animals with esophageal involvement showed more proliferative, raised, necrotic lesions. The lesions varied in size from 1-5 mm, circular, raised lesions to up to 1 cm wide and 4 cm long coalescing, raised, proliferative lesions. Some animals showed extensive, coalescing ulcerations involving greater than 50 percent of the upper esophageal mucosa, which contained firm, yellowish, plaque-like necrotic debris that was not proliferative.
“Mucosal lesions of the larynx showed large, 1 cm, circular to ovoid mucosal ulcerations with necrotic material but in other animals the lesions were small circular (3-5 mm), raised, proliferative lesions. Gross lesions of the tongue were observed in two animals. One animal showed circular, 3-5 mm ulcerations but the other animal had circular, raised, proliferative, 3-8 mm lesions.”
Based on the severe oral lesions, differential diagnosis included vesicular stomatitis, papular stomatitis and footand- mouth disease. Samples from 11 of the dead calves were tested by virus isolation and immunohistochemistry (IHC) in Robert Fulton’s lab in the Department of Veterinary Pathobiology at Oklahoma State University. At least one tissue from each of the 11 fatalities was positive for BVDV by IHC. Comparison of sequences from the isolated viruses, conducted at the National Animal Disease Center, demonstrated that the same BVDV2 strain was isolated from animals in both lots. Due to the timing of the mortalities, it is hypothesized that the BVDV2 infection originated in lot A and then spread to lot B. No further outbreaks of this disease were subsequently seen in this feedlot.