An adult female cougar (Felis concolor) suspected to have been involved in a human attack in far west Texas was trapped and euthanized. The animal was submitted to the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) for diagnostic testing. At necropsy, the carcass was thin with no visceral or subcutaneous fat. Other significant gross findings included two, approximately 2 cm diameter, firm, raised, crateriform nodules that partially occluded the pylorus. On cut surface, the nodules were cystic and filled with numerous, thin, approximately 1 cm long, reddish nematodes and necrotic debris. The small intestine contained moderate numbers of cestodes and some roundworms. Two approximately 2 cm mucosal ulcers were observed in the jejunum. The animal tested negative for rabies, tularemia, plague, E. canis, Lyme borreliosis, FeLV, FIV and had a low positive titer for RMSF.
The helminths discovered in this case were examined by TVMDL staff parasitologist, Dr. Tom Craig. The nematodes in the pyloric nodules were identified as Cylicospirura subaequalis. The cestodes were identified as Taenia pisiformis (intermediate host is the rabbit), and the round worms identified as Toxascaris leonina. Only two species of Cylicospirura are found in sylvatic felids in North America, C.subequalis, and C. felineus. Although there is some spillover, the former is typically associated with mountain lions and encysts in the proximal duodenum and only rarely in the stomach. Conversely, C. felineus is associated with bobcats and encysts in the stomach almost exclusively. C. subequalis has been previously reported in mountain lions in Texas, Oregon, and Washington. The life cycle is obscure, but probably involves an intermediate host such as an arthropod (beetle) or a vertebrate paratenic host. Phylogenetic analyses of worm DNA sequences from both species indicate they are most closely related to Spirocerca lupi. TVMDL speculated that the combination of partial pyloric obstruction and inflammation, intestinal ulceration and intestinal parasitism may have caused intermittent, if not prolonged, regurgitation/vomiting, inappetence and suboptimal nutrient assimilation. The result was starvation and possible “problematic” behavior (adverse interaction with humans).
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