Equine Pathology Workbook

Water Deficiency and Dehydration

Water deficiency is caused by the lack of a source of clean, fresh water. Without access to drinking water the body tissues become dehydrated, causing a relative increase in tissue oncotic colloidal pressure and a relative increase in vascular hydrostatic pressure. This forces fluid out of the into the . The loss of fluid from the blood results in hypovolemia. Horses that are sweating excessively, lactating or are exercising in hot and humid weather are predisposed to dehydration. The clinical presentation of dehydration and water deficiency includes tissue dehydration, polydipsia, anhydrosis, impaction colic, hypovolemia, hypotension, ataxia, coma and death.

Diagnosis can be made through clinical signs and symptoms, dehydration

&

serology. Treatment includes the administration of IV fluids.

Nutritional Excesses in the Horse

Salt (Sodium Chloride) Toxicity

Salt toxicity is rare in horses but may be caused by limited access to fresh drinking water or by drinking water. The clinical presentation of salt toxicity includes ptylasim, polydipsia, colic, diarrhea, ataxia, circling, blindness, seizures, paresis, knuckling of the hind limb or dragging of the toes of the hind limb, weakness, recumbency & death Diagnosis is made through serology and treatment includes IV fluids and free access to fresh drinking water.

Selenium Toxicity and Alkali Disease

Selenium toxicity is usually related to the

supplementation of selenium. Foals and

horses that ingest seleniferous plants are predisposed to selenium toxicity.

The clinical presentation of selenium toxicity includes a smell on the breath, cracking of the hooves at the coronary band, lameness, stiff joints, lethargy, dullness, emaciation, alopecia seen most clearly at the mane and tail and sloughing of the hoof wall. High toxicity in the acute stage can lead to cardiac & respiratory failure and CNS signs. Diagnosis is made through clinical signs and symptoms as well as serology and treatment includes restricting selenium intake.

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