Clinical expression of lolitrem B (perennial ryegrass) intoxication in horses.

This research investigates the effects of lolitrem B intoxication in horses, a toxin found in perennial ryegrass, and explores the potential for a diagnostic test using ELISA. The study finds that intoxication leads to tremors and balance disorders among other symptoms, and the severity of these symptoms does not correlate with the detected levels of lolitrem B in the horses’ bodies.

Objective and Methodology

The study aimed to understand better the clinical impacts of horses ingesting lolitrem B, a mycotoxin found in perennial ryegrass. This neurotoxin was suspected to induce a condition commonly called the ‘ryegrass staggers,’ featured by tremors and lack of coordination among horses.

The researchers used seven horses for the experiment, which they exposed to 2 ppm of lolitrem B for two weeks through ryegrass seed and hay. They carried out a detailed neurological examination before and after the exposure period, employing clinical examination and video documentation methods.

Results of the Study

Upon exposure to lolitrem B, all the horses developed tremors of varying intensity and showed signs of ataxia, a condition affecting balance and coordination. The researchers noted that the level of tremors was dependent on the horse’s level of activity and even manifested as a subtle, rapid tremor in the eyeball.

Ataxia primarily caused irregular limb placements and truncal sway and became more pronounced when the horses were blindfolded. Moreover, contrary to expectations, the study found no correlation between the severity of symptoms and the detected levels of lolitrem B in the horse’s plasma or urine.

Apart from these neurological symptoms, the most severely intoxicated horses also displayed physical symptoms such as limb swelling, heel lesions, and serous nasal discharge. The researchers suspect ergovaline, a compound found in perennial ryegrass, may have caused these symptoms.

Conclusion

The ingestion of lolitrem B results in significant behavioral changes in horses and induces symptoms such as action-related tremors and symmetrical vestibular ataxia. Although these symptoms do not correlate with the toxin’s detected levels in horse plasma or urine, the researchers suggest that an ELISA test for lolitrem B in plasma may be useful for future diagnosis.

The study thus provides valuable insights into the effects of perennial ryegrass intoxication in horses, laying the foundation for a better understanding of the disease and potential diagnostic methods.