Professional assistance is necessary to conduct physical examinations of the cows and evaluations of their diet and environment.
Although numerous poisonous plants are considered, a common cause is the grazing of dallisgrass.
In searching for chemical poisons, quite often consumption of toxic quantities of lead or arsenic in batteries and lubricating grease of vehicles or machinery can be found.
A dietary cause is likely to produce a common metabolic disorder, such as polio, ketosis, grass tetany, nitrate toxicity, or prussic acid poisoning:
Polio (polioencephalomalacia): The affected cows are thin and have been on a low-protein, low-roughage, and high-sulfate diet and likely were confined and fed a grain diet without roughage. As an affected downer cow attempts to stand, the ankles remain flexed or knuckled over. Immediate treatment to relieve swelling of the brain is necessary to prevent permanent damage to the brain.
Range ketosis (acetonemia, hypoglycemia): The affected cows are thin, on a low-carbohydrate, low-energy diet and likely are stressed from cold weather or are calving and nursing. In addition to the incoordination before the cows went down, they had symptoms of bellowing, wallowing, and licking and pressing against walls, posts, and trees. Immediate treatment is directed to raise the blood sugar and improve glucose metabolism.
Grass tetany (hypomagnesemia): The affected cows are thin, grazing lush pasture high in nitrogen and potassium and likely are stressed from cold, cloudy weather or are calving and nursing. In addition to staggers, the cows had symptoms of tossing head, bellowing, and galloping before going down with convulsions. Immediate treatment is directed to raise the blood magnesium.
Nitrate poisoning and prussic acid poisoning: The early stages of either of these toxicities could cause these symptoms. Examples include nitrate toxicity and prussic acid poisoning. Nitrate toxicity often occurs when cattle are fed sorghum forages that have been stressed by heat or drought. Forages cut for hay or grazed in the field can produce dangerous concentrations of nitrate. Prussic acid toxicities also tend to occur when cattle graze drought- or frost-damaged summer annual plants.
