Visceral lesions in wild carnivores naturally infected with Spirocerca lupi.

Aortic lesions pathognomonic for Spirocerca lupi were found in 123 of 150 (82%) coyotes, Canis latrans, 23 of 66 (35%) bobcats, Felis rufus, one of five gray foxes, Urocyon cinereoargenteus and one of two red foxes, Vulpes vulpes, examined in West Texas. Adult nematodes in the esophagus were recovered from 11 of 150 (7%) coyotes. In the aorta there was initially an acute inflammatory response followed by an eosinophilic granuloma surrounding larval nematodes. The principal lesions was scarring of the aorta with replacement of elastic tissue with collagen. There was blockage of the intervertebral arteries, pitting and formation of granulomatous nodules on the intimal surface and scarring with diverticula and anuerysms in affected animals. The response to adult nematodes in the esophagus was usually a small eosinophilic granuloma surrounding the worms. There was no evidence of esophageal sarcoma or spondylosis deformans of thoracic vertebrae as reported in the dog.