| CWD | TB | Johne's |
Elk and deer are susseptible to diseases and health related problems just like any
other animal. The conditions of your pasture, the method a rancher uses to feed the
stock, and the geographical region where the ranch resides all leads to different health
concerns and general condition of the herd.
Here are some of the diseases that affect all ranchers. Every rancher needs to be
aware of these potential problems and keep an eye on the every animal and the condition of
the herd in general. More disease threats will be added on a periodic basis.
Chronic Wasting Disease (CWD)
Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy of deer and
elk that has only occurred in limited areas in the Western United States and some
Provinces of Canada. It was first recognized as a clinical syndrome in 1967 and is
typified by chronic weight loss leading to death. This is similar to Mad Cow Disease
in the Cattle, or Scrapie in Sheep.
Most cases of CWD occur at 3 to 6 years of age. The disease is progressive and
always fatal. The most obvious and consistent clinical sign of CWD is weight loss
over time with the rest of the herd in good shape. Behavioral changes also occur in
the majority of cases, including decreased interactions with other animals, listlessness,
lowering of the head, blank facial expression, and repetitive walking in set patterns
within a pen.
There are no live animal diagnostic tests, so definitive diagnosis is based on
postmortem examination, but game ranchers and government officials are working on a test
for live animals. The origin and mode of transmission of CWD is unknown although
transmission is thought to be lateral, and possibly maternal.
Tuberculosis is a disease that can affect many mammals (yes, this includes humans).
There are three kinds of Tubercle Bacilli. They are known as the human,
bovine, and avian. The principle reason tuberculosis is so hard to cure is that the
microbes have a wax-like covering that protects them against destruction by certain of the
white blood cells. The malady commonly ends with a slow wasting away of the tissues
especially in old animals.
The disease is spread in food, water and air. Bovine Tuberculosis in Elk and
Cattle is the most dangerous. Elk can get Avian TB from birds around the property or
around the feed areas. This type of TB is not harmful to the elk, but can show
positive signs during the single cervical TB test period.
The testing for Bovine TB in elk involves shaving an area on the neck and injecting a
small amount of TB to see how if the injected area swells up after 3 days (this is known
as the single cervical test). If there is any sign of swelling, it is considered a
reaction and then another test must follow - either a comparable cervical test (shaving
the neck area on the opposite side and injecting two samples of TB and then comparing the
growth of each to each other after 3 days) or blood sample test (some states do not allow
this test, but it does cost the animal owner around $100). If either of these tests
show positive, then the animal is labeled a suspect and required to be checked for one
more test prior to a final determination that TB existed. This final test requires
samples of the animals that can only be taken upon necropsy (the animal must be destroyed)
and a culture is grown from these samples. The culture takes 90 days so the herd the
animal belong to (and all animals on the property) in question are under a quarantine for
90 days until the results shows conclusive evidence. If after 90 days the culture
shows no sign of TB growth the herd is released from quarantine. Some states have a
TB program so the loss of the animal to TB can be partially reimbursed - the USDA also has
a program to allow around $750 for the animals loss as well.
The single cervical test is around 80-90% accurate and only as accurate as the vet
doing the work. The comparable cervical test is closer to 95-99% accurate and again
only as accurate as the doing the work. The culture test is 100% accurate.
reservoirs of Bovine TB in New Zealand
surveillance Program Proven Effective
Johne's Disease is an infectious disease of hoffstock caused by Mycobacterium
paratuberculosis. This is not the same as TB, but in the same general area.
Animals with Johnes may test positive in a single cervical TB test, but should show
negative in the comparative cervical TB test. Tests for herd certification for
Johnes is under way and the regulations are currently in draft mode.
Young animals become infected most easily but symptoms may not appear until animals are
three or four years old. Symptoms include loss of condition while appetite remains
good, thirst, diarrhea with out straining, rough coat, dry skin, and no fever.
Animals seem to recover but symptoms later appear again. Toward the end, animals
refuses to eat. Practically all animals that show symptoms die within a period of
one month to two years.
DRAFT - Johne's Disease-Cervid Herd Certification
State Veterinary Laboratory