This incoordination results from eating paspalum grasses
(Paspalum spp) infested by
Claviceps paspali. The
life cycle of this fungus is similar to that of C purpurea (see Ergotism). Toxic infestations are most likely after
humid, wet summers. The yellow-gray sclerotia, which mature in the seed heads in
autumn, are round, roughened, and 2–4 mm in diameter. Ingestion of sclerotia causes
nervous signs in cattle most commonly, but horses and sheep also are susceptible.
Guinea pigs can be affected experimentally. The toxicity is not ascribed to ergot
alkaloids; the toxic principles are thought to be paspalinine and paspalitrem A and
B, tremorgenic compounds from the sclerotia.
A sufficiently large single dose causes signs that persist for
several days. Animals display continuous trembling of the large muscle groups;
movements are jerky and incoordinated. If they attempt to run, they fall over in
awkward positions. Appetite remains good, and animals will eat if feed is provided.
Affected animals may be belligerent and dangerous to approach or handle. After
prolonged exposure, condition is lost and complete paralysis can occur. The time of
onset of signs depends on the degree of the infestation of seed heads and the
grazing habits of the animals. Experimentally, early signs appear in cattle after
sclerotia at ~100 g/day has been administered for >2 days. Although the mature
ergots are toxic, they are most dangerous just when they are maturing to the hard,
black (sclerotic) stage.
Medical treatment is usually not necessary, unless animals
have physical injuries or are compromised from dehydration or lack of eating.
Recovery follows removal of the animals to feed not contaminated with sclerotia of
C paspali. Animals are less affected if left alone and provided
readily available nutritious forages. Care should be taken to prevent accidental
access to ponds or rough terrain where accidental trauma or drowning could occur.
Topping of the pasture to remove affected seed heads has been effective in
Last full review/revision December 2014 by Gary D. Osweiler, DVM, MS, PhD