A rancher pulls into the clinic you are working at and rushes in to say his horse is having difficulty breathing. You assist the vet in examining the horse and note that the horse is in respiratory distress. He has dilated pupils and bright red mucous membranes. You are asked to pull blood for testing which you note is also bright red in color. Which of the following may cause this in the horse?

- Chronic Obstructive Pulmonary Disease (COPD) - Walnut toxicity - Cyanide toxicity - Choke

Cyanide toxicity would have caused the symptoms like dilated pupil, bright red mucous membranes, and respiratory distress in the horse.

Explanation:

Etiology: Grazing on forage crops like grasses, fruits which are pitted and with increased levels of cyanide. The cyanide content in such plants increases if the leaves are wilted, cut, crushed, trampled or damaged in any other way and also due various environmental causes like wind, pests etc. Other sources include fertilizers, pesticides, tobacco smoke etc

Cyanide toxicity: Increased levels of prussic acid (hydrocyanic acid) turns lethal to the horses and basically prevents oxygen supply to the cells of the body.

Types: Acute and chronic cyanide toxicity

Symptoms: Include rapid pulse, excited or stressed out behavior, rapid with labored breathing, drooling, decreased heart rate, mucous membranes that turn bright red or pink, bright cherry red colored blood, collapse, dilated pupil, coma etc.

Diagnosis: Blood test, urinalysis, physical examination

Treatment:

Restoration of oxygen supply Medical treatment Adding cyanide binders like sodium salts, molasses, etc