Pregnancy and Disease Analysis of Captured and Radio-Collared Teton Ewes

Completed by: Wyoming State Veterinary Laboratory, Laramie, Wyoming
Date: 3/28/2008

17/20 ewes tested positive for pregnancy.
2 of the non-pregnant ewes had not yet reached reproductive maturity (< 3 years old).

· All bighorn sheep blood samples tested negative for:

Brucella ovis, wildlife brucellosis serology, epizootic hemorrhagic disease
virus (EHD), paratuberculosis (Johne’s disease), bluetongue virus, parainfluenza virus
(PI3), respiratory synctial virus (RSV), bovine viral diarrhea type 1a & type 2 (BVD),
infectious bovine rhinotracheitis (IBR), ovine progressive pleuropneumonia (OPP), caprine
arthritis encephalitis (CAE).

· All bighorn sheep ear swabs tested negative for mites.


These disease test results are unusual for a bighorn sheep population. Most bighorn sheep populations in Wyoming have been previously exposed to or are currently infected with some of these diseases. Many of these diseases are tested for using serological assays, which identify the presence/absence of antibodies to the particular disease, not the disease itself. Serological assays indicate whether an animal has ever been exposed to a disease, and thus, developed antibodies to it. In the case of these Teton bighorn sheep, the serological assays produced results showing no or very low previous exposure levels.

From a disease point of view, these results suggest that this population is likely to have been isolated from mixing with other populations for a long time.