Buffalo are susceptible to internal parasites, especially young or stressed animals.
This is exacerbated by the fact we now intensively graze with large concentrations of animals in smaller areas. Bison in the wild or on large tracts of land graze and move on, which means they seldom re-expose themselves to parasitic larvae.
Bison naturally are nomadic, so when we fence them into small enclosures, the parasitic burdens can quickly become huge.
Controlling internal parasites must be an integral part of a herd health program.
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Producers should have their veterinarians do various fecal samples throughout the year to determine how great the parasitic burden is in the herd.
These are easy and almost always are done in house, so results are quickly obtained. Parasitic numbers are often falsely lower in the winter. Because parasites are survivors, producing more eggs in the warmer months, fecal counts at this time are a truer reading.
Egg counts of 50 eggs per gram or greater are considered significant. A good average can be obtained by randomly gathering a few samples of fresh manure.
A few species of parasites can be identified by their egg type and some are more significant than others. A veterinarian can best advise on severity of the problem.
If lungworms are suspected, a different type of fecal flotation is done, again usually in house, but the results take several hours to quantify. No dewormers are officially approved for use in bison in Canada, and only Ivomec in the United States, so all applications would require a veterinary prescription.
Worms can kill if they are severe enough, but the first signs are often poor weight gains in young calves and poor fertility in mature stock. Dull hair coats, slower shedding in the spring and increased susceptibility to other diseases such as pneumonia may be the first clues that worms are present.
The two best times to deworm are during fall processing and just before the animals are released onto pasture, where overwintered larvae and eggs are picked up. Wet cool weather in the spring favours parasitic larvae survival and increased worm burdens.
Injectable and pour-on endectocides effectively treat internal parasites common to bison. Most producers I work with prefer the injectable form because dosages can be fine tuned, especially if weighing the animals at the same time.
The pour-ons must not be applied when bison are shedding their winter coats because the dead hair follicles will not absorb the material. Push the application gun down through the hair to insure proper absorption. These products are commonly applied in the late fall during yearly processing along with other procedures commonly done to bison such as pregnancy diagnosis and vaccinations.
A dilemma I run into is how to effectively deworm if late spring fecal analysis shows worm counts are up.
Running bison cows with calves through the chute at this time of year is out of the question. Several good options are available. A product called Safeguard, with the active ingredient fenbendazole, is effective when administered in the feed.
The bison dosage for Safeguard is two times the amount given to cattle.
Many producers occasionally give their bison grain as a treat. Provided trough space is adequate and all or most of the herd consumes the grain at once, mixing in Safeguard could have desirable results. However, there are always a few timid animals that hold back.
With the advent of remote watering systems for bison, such as tanks, solar pumps and windmills, we now have a good mechanism to facilitate deworming.
As long as there is no other source of water, a close approximation of water consumption can be made based on size and ambient temperature. A water soluble product that stays in suspension can be added and mixed in the water.
The only product I could find on the market for this application is a Tramisol cattle obelet. The active ingredient is levamisole and previous advice suggested bison be dosed about 10 percent higher than cattle.
The obelets can be dissolved in water and should be an effective way to deworm. Continue to use your veterinarian to monitor parasite levels in your herd.
Roy Lewis is a veterinarian practising in Westlock, Alta.
