North American Veterinary Licensing Examination (NAVLE) Practice Test

What type of toxin is associated with Crotalaria spp. in an equine patient?

1. Nitrate

2. Organophosphate

3. Cyanide

4. Pyrrolizidine alkaloid

The correct answer is: Pyrrolizidine alkaloid

Crotalaria spp. is well-known for containing pyrrolizidine alkaloids, which are toxic compounds that can cause serious liver damage in equines and other animals. When ingested, these alkaloids undergo metabolic activation in the liver, leading to the formation of reactive metabolites that can cause cellular damage and necrosis. This mechanism of action is particularly concerning as it can lead to conditions such as hepatotoxicity, cirrhosis, and even failure of the liver. Understanding the specific effects of pyrrolizidine alkaloids helps veterinarians in diagnosing and managing cases of poisoning in horses. Signs of toxicity include weight loss, jaundice, and liver failure, often resulting from chronic exposure to plants containing these alkaloids. The other types of toxins listed do not relate to Crotalaria spp. While nitrates and cyanides are toxins associated with different plants and can cause various toxic syndromes, they are not linked to the Crotalaria species. Organophosphates, primarily known for their role in insecticides, are another category of toxin that is unrelated to the issues caused by Crotalaria. Thus, recognizing that pyrrolizidine alkaloids are the primary concern when discussing Crot