Source: South Dakota State University
Weather conditions this spring and summer are proving to be just right for ergot poisoning that can affect cattle on pasture, says Russ Daly South Dakota State University Extension Veterinarian.
"Cool, damp spring weather followed by the recent heat means that grasses are at increased likelihood of becoming infected with ergot bodies," Daly said.
Ergot bodies appear as dark brown to black growths on top of the seed heads of grasses and grains. The growths vary in size. Ergot bodies result from infection of the grain by a fungus called Claviceps purpurea, which grows very well in warm weather and infects over 200 species of grasses throughout the country. Examples of plant species infected include; wheat, barley, oats, brome grass, and wheatgrass.
All domestic animals are susceptible to the effects of ergot; however, due to their diets, ruminants are usually more commonly affected than others Daly says.
The ergot bodies contain several toxic substances produced by the fungus, called ergot alkaloids explains veterinary pathologist, Regg Neiger.
"The effects of these toxins on animals can vary widely and cause both problems systemically overall, as well as with the extremities of the animal," Neiger said.
Symptoms to watch for
In cattle, a common peripheral effect of ergot poisoning is a constriction of the small blood vessels to their extremities, like the ears, tail, and feet. Blood flow may be compromised, and in severe cases, result in gangrene, or a sloughing off of hooves and the distal parts of ears and tails.
Initially, animals may appear to be in pain and lame; this may be initially confused with other causes of lameness on pasture such as foot rot. However on closer examination, the extremities of animals affected with ergotism are cool to the touch, and there is a line of demarcation between normal and non-healthy tissue. Other initial signs of ergotism are also quite non-specific: increased susceptibility to heat, reduced feed intake, rough hair, weight loss, and decreased milk production.
Systemically, cattle may less commonly show signs of nervous system problems. Excitability and tremors may be present, especially when cattle are forced to move.
Sheep are susceptible to ergotism as well, but tend to show milder clinical signs than cattle. Swine fed grain contaminated with ergot can show feed refusal and decreased weight gain. Gangrene is less of a problem in swine, but occasionally edges of ears and snouts may slough. In sows, ergot is associated with reduced milk production, infertility and early parturition, resulting in birth of smaller, weaker pigs.
Diagnosis of ergotism is usually made on the basis of clinical signs in the animal and presence of large numbers of ergot bodies in grain or on grass in pasture. Chemical analysis of suspected grass, hay, or grain for the ergot alkaloid toxins can be performed if needed.
How to treat animals with ergotism
Treatment of ergotism in affected animals relies on removal of the animals from the offending feed source and providing supportive care to manage pain, stress, and secondary infections of the affected body parts.
Preventing ergotism involves removing animals from infected pasture if possible. Mowing or pasturing grass before it flowers will prevent the formation of ergot bodies on grasses.
If you think your livestock may be affected by ergotism, contact your local veterinarian.