Since the onset of winter, the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) has seen quite a few cases of intoxication in cattle that have consumed the coffee senna (Senna occidentalis) plant. Most of the cases involved adult cattle that were found dead by the owners. The diagnosis was made by finding evidence of the plant in the rumen contents (Figure 1) and compatible organ and muscle damage observed on histopathology. In a few cases that were found prior to death, affected animals displayed signs of recumbency and dark urine which contained myoglobin. Affected animals are sometimes referred to as “alert downers” because they can continue to eat and drink, but are unable to stand.
Coffee senna plants are woody and erect, reaching 6 to 8 feet in height and produce long, upright beans or pods in the fall (Figure 2). All portions of the plant are toxic. Although the plant is not particularly palatable, cattle will consume it when there is not much other forage available for grazing. Most of the cases this year occurred within a few weeks of the freeze that reached deep into Texas in mid-November. Once leaves are freeze-killed, palatability increases. Supportive treatments have been suggested, but are usually unrewarding once cattle are down, and the degree of toxicity is related to the amount of plant material consumed.
Besides coffee senna, there are other toxic members of the Senna genus in Texas. Twin-leaf senna (Senna roemeriana) grows on calcareous soils west of I-35, and Lindheimer’s senna (S. lindheimeriana) grows farther south and west. Sicklepod senna (S. obtusifolia) grows along the gulf coast. Cattle are affected with large muscle group damage in the same way by these other species. In the Texas hill country region, goats tend to consume twin-leaf senna, and they suffer primarily cardiac muscle damage. Chickens that consume the plant are affected similarly.
For more information about TVMDL’s test offerings, visit tvmdl.tamu.edu or call 1.888.646.5623.
REFERENCES
Welborn, M.G. (2008). Anthrax. Blackwell’s Five-Minute Veterinary Consult: Ruminant. S. R. R. Haskell. Ames, IA, Wiley-Blackwell: 826-827