University of Kentucky College of Agriculture, VET-35 Food and Environment Cooperative Extension Service

Forage-Related Cattle Disorders Staggers (Tremorgenic Syndrome) Michelle Arnold, Veterinary Diagnostic Laboratory

Table 1. Three main grass types associated with tremorgenic syndrome. “Staggers” is an all-inclusive term for a group of nervous system disorders Indole-diterpenoid Species caused by indole-diterpenoid mycotoxins Disease/Grass Affected Fungus Mycotoxins: “Tremorgens” Affected produced by various types of fungi on Perennial Ryegrass Staggers Neotyphodium lolii Lolitrem B Cattle, Sheep forages. These mycotoxins are collec- Grass: Lolium perenne Paxilline Horses, Llamas tively known as “tremorgens” (Table 1), Staggers Claviceps paspali Paspalitrems A-C Cattle, Horses and they may be found in several types Grass: P. dilatatum (Dallisgrass) paspalinine Buffalo of grasses at varying stages of maturity. Grass: P. notatum (Bahiagrass) The three main grass types associated Bermudagrass Tremors Claviceps cynodontis Paspalitrems A & B Cattle, Horses with tremorgenic syndrome are Pas- Grass: Cynodon dactylon Paspaline palum spp. (dallisgrass and bahiagrass), paspalinine Cynodon dactylon (bermudagrass) and Lolium perenne (perennial ryegrass). Clinical signs are characterized by Regardless of fungal type, clinical • As the condition worsens, the animal tremors and incoordination that tend to signs of staggers are similar. may exhibit staggering, head shaking, worsen with excitement or movement. • When at rest, animals appear to move salivation, collapse and seizures or Cases of perennial ryegrass staggers and graze normally. other neurologic signs (opisthotonus, are most likely to occur when perennial • The earliest signs are head tremors nystagmus). Deaths rarely occur except ryegrass infected with the endophyte and muscle twitching (fasciculations) from accidental trauma or from conse- Neothyphodium lolii is grazed inten- of the neck and shoulders which later quences of being recumbent (downer). sively in the summer and fall. The highest may involve the extremities. • Affected animals usually return to concentration of the tremorgens exists • With excitement or movement, normal movement and grazing after a in the basal leaf sheaths, so cattle are tremors of the head, shoulder and period of rest. A full recovery may be most at risk when the infected grass is flank worsen and are accompanied by expected in approximately 1-2 weeks grazed close to the ground. Alternatively, incoordination, ataxia (wobbling gait) once removed from the infected grass paspalum staggers or dallisgrass staggers or a stiff hopping gait, and/or general and left undisturbed. occurs when animals consume the seed weakness of hind limbs. heads of mature dallisgrass (Paspalum dilatatum) or bahiagrass (Paspalum Dallisgrass (Paspalum dilatatum Poir.) infected with . notatum) infected with the fungus Claviceps paspali. The fungus invades the grass flower and replaces the seeds with a mass of fungal tissue or “sclerotia.” Similarly, bermudagrass tremors occurs when bermudagrass becomes trem- orgenic in late summer and fall when seed heads are infected with the fungus Claviceps cynodontis.

2015©University of Georgia Pathology Archive, University of Georgia, Bugwood.org

Cooperative Extension Service | Agriculture and Natural Resources | Family and Consumer Sciences | 4-H Youth Development | Community and Economic Development In a typical episode, a cow may stand This condition has been described in References with her hind limbs extended in a base- many parts of the world but as yet not in Cheeke, P.R. Endogenous Toxins and wide stance and sway. When forced to . Mycotoxins in Forage Grasses and run, she may have exaggerated movement Staggers has no effective treatment Their Effects on Livestock. Journal of the legs resulting in incoordination other than gently, quietly removing the of Animal Science. 1995;73:909-918. that causes her to fall. She may paddle herd from the infected pasture. Preven- Mostrom, M.S., and Jacobsen, B.J. Ru- violently while attempting to get up. tion is based on minimizing the amount minant Mycotoxicosis. Veterinary After a period of rest, she will sit up, rise of mycotoxin consumed. In the case of Clinics of North America: Food Ani- unassisted and then slowly walk away. Paspalum staggers, prevention is best ac- mal Practice. 2011; 27:315-344, viii. Diagnosis is based upon the clinical complished by scouting the field for signs Pickrell, J.A., Oehme, Fred, and Man- signs coupled with a history of grazing of the fungus in the seed heads and mow- nala, Shajan A. Tremorgenic For- one of the affected grasses. Another ing if the pasture is significantly infected ages In: Plumlee KH, ed. Clinical possible cause of forage-related tremors or by maintaining high grazing pressure Veterinary Toxicology. St. Louis is poisoning by Aspergillus clavatus, a to prevent heavy seeding. Prevention of (MO): Mosby, 2004; 270. mold associated with feeding sprouted ryegrass staggers is based on avoidance Riet-Correa F., Rivero R., Odriozola E., cereals (barley) and sugar beet residues, of heavy grazing that forces livestock to et al. Mycotoxicoses of Ruminants hydroponically grown sprouts or malted graze the lower parts of the plant. Rye- and Horses. Journal of Veterinary by-products. This is a much more severe grass hay cut when the grass is toxic has Diagnostic Investigation, 2013; disease due to degeneration of the brain been shown to retain toxicity for at least 25:692-708. and spinal cord characterized by trem- two years. Prevention of bermudagrass ors, staggering, weakness, paralysis, and tremors is simply avoidance of severely recumbency (downer) followed by death. infected pastures.

Where trade names are used, no endorsement is intended, nor criticism implied of similar products not named.

Educational programs of Kentucky Cooperative Extension serve all people regardless of race, color, age, sex, religion, disability, or national origin. Issued in furtherance of Coop- erative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Nancy M. Cox, Director of Cooperative Extension Programs, Uni- versity of Kentucky College of Agriculture, Food and Environment, Lexington, and Kentucky State University, Frankfort. Copyright © 2015 for materials developed by University of Kentucky Cooperative Extension. This publication may be reproduced in portions or its entirety for educational or nonprofit purposes only. Permitted users shall give credit to the author(s) and include this copyright notice. Publications are also available on the World Wide Web at www.ca.uky.edu. Issued 7-2015