Gossypol poisoning is usually longterm, cumulative, and slowly and subtly harmful. It is caused by eating cottonseed or cottonseed products that contain excess free gossypol.

Gossypol is the major toxic ingredient in the cotton plant. Gossypol content of cottonseeds varies by plant species and variety and by environmental factors such as climate, soil type, and fertilization. Cottonseed is processed into edible oil, meal, linters (short fibers), and hulls. Cottonseed and cottonseed meal are widely used as protein supplements in animal feed. Cottonseed hulls are used as a source of additional fiber in animal feeds and usually contain much lower gossypol concentrations than whole cottonseeds.

All animals are susceptible. Domestic livestock are affected most often, but dogs fed diets that contain cottonseed meal have also developed gossypol poisoning. Guinea pigs and rabbits are most sensitive, followed by dogs and cats. Horses seem relatively unaffected. Toxic effects usually develop only after longterm exposure (weeks to months) to gossypol.

Signs reflect harmful effects on the heart, lungs, liver, kidneys, or reproductive system. Signs of prolonged excess gossypol exposure can include weight loss, weakness, loss of appetite, and increased susceptibility to stress. Prolonged exposure can cause sudden heart failure. Anemia can be another common result. In dogs, heart damage results in fluid buildup within the abdomen. Affected dogs may be very thirsty and have metabolic abnormalities and disturbances in heart rhythm.

Diagnosis is based on 1) a history of eating a diet containing cottonseed meal or cottonseed products over a relatively long period; 2) signs of heart, lung, and liver damage, with fluid buildup in various body cavities; and 3) no response to antibiotic treatment. However, samples of the diet may not be available to be analyzed for free gossypol levels if the feed has already been completely eaten.

Other causes of similar signs need to be excluded. These include antibiotics that can have toxic effects on the heart, nutritional or metabolic disorders (for example, selenium, vitamin E, or copper deficiency), infectious and noninfectious diseases, toxicoses caused by fungus-contaminated grain, and some plant poisonings.

There is no effective treatment for gossypol poisoning. All cottonseed products should be removed from the diet immediately if gossypol poisoning is suspected. However, severely affected animals may still die up to 2 weeks later. Recovery depends primarily on the extent of the toxic effects on the heart. Supportive treatment includes feeding a high-quality diet supplemented with lysine, methionine, and fat-soluble vitamins.

Last full review/revision July 2011 by Barry R. Blakley, DVM, PhD; Cheryl L. Waldner, DVM, PhD; Rob Bildfell, DVM, MSc, DACVP; William D. Black, MSc, DVM, PhD; Herman J. Boermans, DVM, MSc, PhD; Cecil F. Brownie, DVM, PhD, DABVT, DABT, DABFE, DABFM, FACFEI; Raymond Cahill-Morasco, MS, DVM; Keith A. Clark, DVM, PhD; Gregory F. Grauer, DVM, MS, DACVIM; Sharon M. Gwaltney-Brant, DVM, PhD, DABVT, DABT; Larry G. Hansen, PhD; Safdar A. Khan, DVM, MS, PhD, DABVT; Garrick C. M. Latch, MASc, PhD; Gavin L. Meerdink, DVM, DABVT; Lisa A. Murphy, VMD; Frederick W. Oehme, DVM, PhD; Gary D. Osweiler, DVM, MS, PhD, DABVT; Mary M. Schell, DVM; David G. Schmitz, DVM, MS, DACVIM; Norman R. Schneider, DVM, MSc, DABVT