Avocado Poisoning in Horses
Raising avocados may be detrimental to the health of your horse. Avocado leaves, fruit, bark, and seeds all contain persin and an unidentified cardiac toxin. In lactating mares, persin produces a non-infectious mastitis (inflammation of the mammary glands), epithelial necrosis (skin cell death over the mammary glands) and agalactia (decrease in milk production). Occasionally gastritis and colic may occur. Additional clinical signs are related to myocardial necrosis (death of the heart muscle cells) and include dyspnea, coughing, and increased respiratory and heart rates. Other cardiac changes that may occur include cardiac arrhythmias, edema of the neck, lips, tongue, mouth and ventral abdomen, cyanosis (bluish discoloration due to lack of oxygen), anorexia, generalized weakness and recumbency (inability to get up).
The heart damage may be fatal and the cardiac changes are largely irreversible; therefore, access to avocado groves should be prevented for horses.
Stegelmeier, Bryan. "Myotoxic Plants: Identifying Poisoning Signs, Sequelae." DVM. October 2007. Pp. 16E-17E.
Smith, Bradford. Large Animal Internal Medicine. 2nd Ed. Mosby. St. Louis. 1996. P. 1889.