We are doing a study to establish this. It clearly happens, but the percentage is low. No precise figures are available yet. Many factors are likely to affect the probability that a subclinically affected bison will develop clinical disease. One of the most important of these is stress.

Our limited knowledge on this subject suggests that bison may be infected for extended periods, in some instances years, before developing MCF. More work is needed on this aspect of the disease.

The best one to use for diagnosing active disease is the PCR test. Blood collected into an EDTA-anticoagulant tube (purple-top tube) is the best sample to obtain from live animals. Both the PCR test and a newly developed serological test can be run on one purple-top blood sample. The carcass of an animal that dies of MCF-like signs should be examined post-mortem by your veterinarian or better still a pathologist at a veterinary diagnostic laboratory.

Our limited knowledge on this subject suggests that bison may be infected for extended periods, in some instances years, before developing MCF. More work is needed on this aspect of the disease. A recent study performed by a veterinary epidemiologist in Canada, Dr. John Berezowski at WCVM in Saskatoon, demonstrated that bison develop clinical signs as soon as 52 days and as late as 8 months after exposure to infected sheep.

With currently available test methods, between 15 and 23%. This is a minimal figure. No test is perfect. It is entirely possible that the tests currently being used for identifying infected normal bison miss a significant percentage of animals. The true rate of subclinical infection could be significantly higher than this.

Yes. Bovine viral diarrhea, salmonellosis and pneumonia complex, among others, can be confused with MCF: Testing sick animals is the key to establishing an accurate diagnosis.

Most infections are characterized by depression, separation from the rest of the herd, loss of appetite, and in many bloody diarrhea. Unlike MCF in cattle, discharge from the eyes and nasal passages of affected bison is minimal. Animals develop a fever and may pass bloody urine. The clinical course is generally 1 -7 days. Most animals die within 3 days of developing clinical signs.

Animals older than 6 months, particularly if stressed by bad weather, transportation and handling. Large outbreaks occur in feedlots, where stress due to crowding is likely.

Following transmission, the MCF virus is presumed to infect lymphoid tissues (spleen and lymph nodes) and cells lining the gut, urogenital tract and nasal passages. The severe inflammation generally causes gastroenteritis, with widespread formation of ulcers particularly in the large bowel. This is the basis for bloody diarrhea, a common and useful diagnostic sign of MCF in bison.

MCF virus is transmitted by sheep in most instances. There is no documented evidence of person-to-bison transmission. Normal veterinary infection control precautions should be followed when caring for a bison suspected to have this viral infection.

Natural infections occur in many species of deer such as elk, reindeer and moose, as well as a variety of exotic ruminants. The disease can be transmitted experimentally to laboratory species, but there is nothing to indicate these species are involved in natural transmission. MCF was recently reported in pigs for the first time.

Three tests are available: histopathology, serological testing for MCF and an OvHV-2 specific test using the polymerase chain reaction (PCR).

We are aware of cases in 11 states (Utah, Wyoming, Colorado, Montana, California, Oregon, Ohio, Kansas, Nebraska, North and South Dakota) and three Canadian provinces (Saskatchewan, Ontario and Alberta). The disease is widespread in the bison industry and is commonly misdiagnosed due to lack of specific clinical signs.

There is no reason at this time why such animals should be culled. An important question we are trying to answer is whether healthy test-positive bison are at a significantly higher risk of developing MCF compared to healthy test-negative bison.

We think it is rare. There are inherent problems in tracking diseases like MCF in wild bison. The number of studies of MCF in public herds is small.

There is no evidence that transmission occurs horizontally from one bison to another. Currently we are doing a study supported in part by the National Bison Association to establish whether bison-to-bison transmission is a factor in natural outbreaks.

Yes. There are generally no lesions in the fetus or placenta. It is assumed that abortion is a result of illness in the dam, rather than infection of the fetus. Dams die shortly after they abort.

There is no reason at this time why such animals should be culled. An important question we are trying to answer is whether healthy test-positive bison are at a significantly higher risk of developing MCF, compared to healthy test-negative bison.

Osteoporotic fractures may occur spontaneously while standing, walking or sitting – and even while sleeping. Simple movements such as lifting a shopping bag or carrying your grandchild may cause a fracture. Each fracture increases the risk of suffering the next one. Osteoporosis and vertebral fractures may lead to deformation of the vertebral column (so-called hunchback), which may limit respiratory function or cause painful and problematic displacement of internal organs.

Avian pox is another common disease that affects a bird’s eyes. This disease causes warty lesions on the head, legs, and feet, but cannot always be easily distinguished from conjunctivitis. Avian pox is transmitted by biting insects, by direct contact with infected birds or contaminated surfaces (e.g. feeders), or by ingestion of contaminated food or water. Just as with conjunctivitis, the infected bird becomes vulnerable to predation, starvation, or exposure. MORE PHOTOS

Clinical signs vary depending on the severity of the episode. In mild cases, affected horses may be slightly stiff after exercises. At the other end of the spectrum, pain may be so intense that affected horses may be unable to stand and bear weight. Exercise may elicit a short, stiff stride. Following rest, horses may be reluctant to move and may adopt an unusual stance; males often posture as if to urinate. Horses may also sweat liberally and more than the degree of exertion would dictate.