Fall Health Concerns for Horses

Fall HorsesFall can be a beautiful time of year for horseback riding. However, falling leaves and frost can negatively impact horse health.
Ingestion of dried or wilted, but not fresh, maple leaves is associated with the toxicosis. Dried leaves are not generally believed to retain toxicity the following spring. Toxicosis normally occurs in the autumn when normal leaf fall occurs. Although studies indicate that leaves collected after September 15 are more toxic, cases of toxicosis in horses due to wilted leaves after summer storms have been observed. Horses are the only species for which maple leaf toxicity has been reported. Horses are often depressed, lethargic, and anorexic with dark red or brown urine after the first day of ingestion. They may progress to going down with labored breathing and increased heart rate before death. Horses should be fenced out of areas where wilted maple leaves are plentiful.
Prunus species (species in the cherry family) contain cyanide and should be removed from horse pastures. Cyanide is released after chewing the plant or seed, or when the plant material wilts (after a frost). Animals are most commonly found dead within minutes to a few hours of ingestion of the plant.
There are no reports of toxicity of horses grazing frost damaged pastures (includes grass and legume species). Frost damaged pastures can have higher concentrations of nonstructural carbohydrates, leading to an increase in potential for founder and colic, especially in horses diagnosed with or prone to obesity, laminitis and Equine Metabolic Syndrome. To reduce the chance of adverse health effects, it is recommended that horse owners wait up to a week before turning horses back onto a pasture after the first killing frost. Subsequent frosts are not a concern as the pasture plants were killed during the first frost.

This article is reprinted with permission from Krishona Martinson, University of Minnesota. This and other horse nutrition articles can be found at http://www.extension.umn.edu/agriculture/horse/nutrition/.

Fall Pasture Management

Fall provides an ideal time of year to improve horse pastures. August 1st to September 15th is an ideal time of year to seed or overseed pastures and rid pastures of perennial weeds. Fall is the best time to seed or re‐seed pastures due to the usually adequate moisture, less weed competition and cooler weather conditions. Fall is also best for perennial weed control since perennial plants are storing carbohydrates in their roots allowing the herbicide to be translocated into the root for effective control.

Make sure to check fences; especially posts. Fix broken posts before they are frozen into the ground. Finally, make sure the pasture grasses have 3 to 4 inches of re‐growth going into winter. This will help with winter survival and a quicker spring growth. Keeping horses on pastures over winter causes damage to plants and offers the horse little nutrition. Keeping the horses in a sacrifice paddock (dry lot) with access to hay, water and shelter is recommended.

Horse owners should use caution when grazing after the first killing frost of the fall. Frost damaged pasture forages can have higher concentrations of non‐structural carbohydrates following the first killing frost of the season. This can lead to an increase in the potential for laminitis and colic, especially in obese horses or horses diagnosed with laminitis and equine metabolic syndrome. To reduce the chance of adverse health effects, it is recommended that horse owners wait one week before turning all horses, including healthy horses, back onto a pasture after the first killing frost.

This article is reprinted with permission from Krishona Martinson, University of Minnesota. This and other horse nutrition articles can be found at http://www.extension.umn.edu/agriculture/horse/nutrition/.