Drought-Associated Livestock Diseases
The Wyoming State Veterinary Laboratory has been seeing or consulting on several disease problems that will be more likely with the extremely dry conditions over most of Wyoming. .
Cow asthma (pulmonary emphysema and edema) is associated with sudden change from dry pastures to meadows, especially regrowth meadows after haying, and could present quite a challenge to producers this year. Most ranches don’t normally move to meadows until after heavy frosts, but this year many are already doing so and cow asthma is showing up. Cow asthma occurs when rumen bacteria convert the amino acid, tryptophan, to a toxic compound that causes an allergic reaction in the lungs. Ionophores such as monensin will prevent ABPE if fed in advance, but many cows won’t eat the blocks and still be affected. Keep a very close eye on cows for a few days after a change to meadows. Gradual adaptation is an option.
Polioencephalomalacia (“polio”) due to high sulfate water or water deprivation is on the rise. This disease is mainly associated with drinking water that has the sulfate concentrated due to evaporation. Alkali ponds are the biggest problem, but even well water may be high in sulfates. The high sulfur content causes brain damage. Clinically, the animals are blind and show nervous signs such as incoordination. Testing stock water is important. Hauling water may be the only option on some ranches or farms.
Bovine respiratory disease, especially BRSV could be quite serious this year with all the dust irritation. Use MLV vaccines with preconditioning shots to help avert it. The killed products have, in some cases, actually increased the lesion severity in BRSV outbreaks.
Consult with your local veterinarian for more information about these disease problems and measures that can be taken to prevent them.