BASICS
- Chronic ingestion of Sorghum vulgare var. sudanense (sudangrass or hybrid sudangrass) causes cystitis, ataxia, and teratogenesis in horses. Grazing of sudan pastures and ingestion of freshly cut hay are associated with the syndrome but feeding of cured hay is not
- Generally, intoxication occurs during periods of high rainfall and rapid plant growth. Fertilization has no effect on toxicity
- The toxin is believed to be a lathyrogenic agent, γ-glutamyl-β-cyanoalanine. Onset of clinical signs is after weeks to months (average of 8 weeks) of grazing a sudangrass pasture
- Geographically, sudangrass is most commonly used as a forage in the southwestern and central USA. Ingestion of Sorghum spp. is also associated with cyanide and nitrate toxicoses (see chapters Cyanide toxicosis and Nitrate/nitrite toxicosis for more in-depth discussion of these intoxications)
Sorghum cystitis—ataxia is more common in mares but can occur in geldings or studs. All ages are susceptible.
- Posterior ataxia and incoordination
- Forced movement enhances ataxia
- Falling when backed up
- Recumbency
- Constant urine dribbling from a full bladder
- Urine scalding
- Cystitis
- Frequent opening and closing of vulva (winking)
- Mares may appear to be in constant estrus
- Fetal malformations (extreme flexion of joint or ankylosis) when mares graze sudangrass between days 20 and 50 of gestation
- Secondary complications of urinary tract and kidney infection
DIAGNOSIS
TREATMENT
MEDICATIONS
FOLLOW-UP
MISCELLANEOUS