Does your horses reside in a selenium-deficient area? If they do, and they’re broodmares, their foals’ health could be at risk.
Foals depend on their dams for dietary selenium. And foals with a selenium deficiency are at risk of developing white muscle disease, which leads to skeletal and cardiac muscle abnormalities. It typically affects foals up to weanling age and has a fatality rate ranging from 30 to 45%.
In an attempt to provide geographical insight into managing and preventing white muscle disease, Catherine Delesalle, DVM, PhD, Dipl. ECEIM, and colleagues from Ghent University, in Belgium, collected data from eight foals with white muscle disease that were admitted to Wolvega Equine Hospital, in The Netherlands.
All foals presented with increased muscle enzymes indicative of the disease and clinical signs including muscle weakness, inadequate suckle reflex, and lethargy. All foals received general supportive care and medication upon arrival, and six received a selenium and vitamin E injection. Two foals did not survive, and post-mortem findings confirmed muscle histopathology (cell structure when viewed under a microscope) consistent with white muscle disease.
All the foals came from one of four farms of the Netherlands. The researchers were able to obtain samples from the dams and other herd members to evaluate selenium and vitamin E status to represent two of those four locales. Further, for three months following, the dams and herdmates received a daily oral selenium and vitamin E supplement.
Some of the team’s key findings included:
- Geographical review of the four premises indicated that all were in areas known to be selenium-deficient;
- After three months of selenium and vitamin E supplementation, blood glutathione peroxidase (a selenium-containing antioxidant used as a selenium status indicator) values improved in mares, foals, and their herdmates in one of the two premises monitored; and
- In the second premises observed, more than half of the mares still showed indications of selenium (7/10) and vitamin E (6/10) deficiency despite three months of supplementation. These horses had a previous history of liver disease due to ragwort poisoning
Based on these findings, the researchers emphasized that owners should focus more on improving selenium concentrations in areas where soil is known to be deficient. The study contains geographical maps that illustrate soil selenium content in different regions of The Netherlands and Belgium (find the publication in full online at ncbi.nlm.nih.gov/pmc/articles/PMC5415829). Such maps are also available for the United States via the U.S. Geological Survey.
Delesalle cautioned that it is important to realize that even in adequate selenium areas, the chemical form of soil selenium might not be readily available to plants and, thus, contribute to deficiencies in animals grazing those plants or hay produced from the field.
“Unfortunately, these soil conditions seem to manifest themselves with increasing frequency in many geographical areas,” says Delesalle.
Owners should perform proper soil maintenance and fertilization, paying particular attention to components that affect plants’ selenium uptake, including acid-base balance and phosphorous levels, should be applied as needed when soil selenium levels fall below 0.6 parts per million; a soil test can help determine level in individual areas.
Also, have your veterinarian monitor the selenium status of broodmares residing in selenium-deficient areas, and provide oral supplementation as necessary to help reduce the likelihood of their foals developing white muscle disease.
The study, “White muscle disease in foals: focus on selenium soil content. A case series,” was published in BMC Veterinary Research.