Salinomycin toxicosis in horses.
Abstract: A 4-month-old American Paint filly was evaluated because of sudden onset of ataxia that progressed to recumbency. Five additional horses from the same and neighboring premises developed signs of poor performance, generalized weakness, ataxia, and recumbency; 2 of those horses were also evaluated. A new batch of a commercial feed supplement had been introduced to the horses' diet on each farm within the preceding 3 days. Results: Other than recumbency, findings of physical and neurologic examinations of the foal were unremarkable. The other 2 horses had generalized weakness and mild ataxia, and 1 horse also had persistent tachycardia. The foal had mild leukocytosis with neutrophilia, hyperglycemia, and mildly high serum creatine kinase activity. Results of cervical radiography, CSF analysis, and assessments of heavy metals and selenium concentrations in blood and vitamin E concentration in serum were within reference limits. Feed analysis revealed high concentrations of the ionophore antimicrobial salinomycin. Results: The 5 affected horses survived, but the foal was euthanized. At necropsy, a major histopathologic finding was severe vacuolation within neurons of the dorsal root ganglia, which was compatible with ionophore toxicosis. The surviving horses developed muscle atrophy, persistent weakness, and ataxia. Conclusions: In horses, ionophore toxicosis should be considered as a differential diagnosis for acute weakness, ataxia, recumbency, or sudden death. Furthermore, ionophore toxicosis should be considered as a cause of poor performance, weakness, muscle wasting, and cardiac arrhythmias in horses. Surviving horses may have impaired athletic performance.
Publication Date: 2007-06-19 PubMed ID: 17571983DOI: 10.2460/javma.230.12.1822Google Scholar: Lookup
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Summary
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This research investigates an incident of salinomycin poisoning in horses, where symptoms such as weakness, coordination loss and recumbency occurred due to the ingestion of a commercial feed supplement containing a high concentration of the ionophore antimicrobial, salinomycin. The findings underscore the need to consider ionophore toxicosis in cases of sudden weakness, ataxia, or recumbency in horses.
Background and Case Presentation
- The article details the case of a 4-month-old American Paint filly who was examined due to a sudden onset of ataxia (loss of coordination) which progressed to the horse being unable to stand up, a state known as recumbency. Five other horses from the same and neighboring premises also developed similar signs.
- These symptoms had begun to appear just three days after a new batch of a commercial feed supplement was introduced to the horses’ diets.
- Among the other horses, two were evaluated in detail. One of them had generalized weakness and mild ataxia, while the other additionally displayed persistently elevated heart rate (tachycardia).
Investigation and Findings
- In addition to recumbency, the filly horse did not show any significant physical or neurological deviations. However, blood tests revealed mild leukocytosis (increased white blood cells), hyperglycemia (elevated blood sugar), and slightly elevated serum creatine kinase activity, an indicator of muscle damage.
- All assessed parameters including cervical radiography, cerebrospinal fluid (CSF) analysis, concentrations of heavy metals and selenium in the blood, and vitamin E concentration in the serum were within normal ranges.
- However, crucially, a feed analysis revealed high concentrations of salinomycin, an ionophore antimicrobial.
Outcomes and Conclusion
- Although five affected horses survived, the 4-month-old filly was euthanized due to severity of condition. Postmortem investigations showed severe vacuolation (formation of vacuoles or cavities) within the neurons of the dorsal root ganglia, a finding compatible with ionophore toxicosis.
- The surviving horses developed muscle atrophy, persistent weakness, and ataxia, implying that exposure to ionophores can cause long-term health issues in horses.
- The findings highlight that ionophore toxicosis could be a potential cause behind sudden weakness, ataxia, recumbency, poor performance, muscle wasting, and cardiac arrhythmias in horses and therefore, it should be considered as a differential diagnosis.
- The authors conclude with a warning that horses who survive this toxicosis might have their athletic performance permanently impaired.
Cite This Article
APA
Aleman M, Magdesian KG, Peterson TS, Galey FD.
(2007).
Salinomycin toxicosis in horses.
J Am Vet Med Assoc, 230(12), 1822-1826.
https://doi.org/10.2460/javma.230.12.1822 Publication
Researcher Affiliations
- Department of Medicine, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
MeSH Terms
- Animal Feed / toxicity
- Animals
- Anti-Bacterial Agents / toxicity
- Diagnosis, Differential
- Fatal Outcome
- Female
- Food Contamination / analysis
- Horse Diseases / chemically induced
- Horse Diseases / diagnosis
- Horse Diseases / pathology
- Horses
- Pyrans / toxicity
Citations
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