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