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. . 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.
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.