Thyroids put out the hormone thyroxin, which helps with many areas of the pony or horse’s health. But if the thyroid glands put out too little, the horse will be ill and listless. It’s unusual for an adult horse to get goitre or hypothyroidism, or under active thyroid glands. It is generally far more common for a horse to get hyperthyroidism, which is when the thyroid glands go into hyperdrive.
But one of the treatments for hyperthyroidism and for thyroid cancer is to remove the thyroid glands. In that way, you need to be aware of the symptoms of hypothyroidism, especially if you do not know the horse’s past history because he or she is a rescue.
Hypothyroidism in Foals
When hypothyroidism is seen, it’s more commonly seen in newborn foals than in adult horses or ponies. The foal will lack energy and have large swellings on either side of his neck. Those are swollen thyroid glands. They usually will not want to stand up to nurse. It’s not entirely known why this happens.
According to “The Complete Equine Veterinary Manual” (David & Charles; 2004) if you can support the foal so he or she can stand and suckle, the problem will go away on its own. The last symptom to disappear will be the thyroid glands going back down to normal size. The foal still should be seen by a vet.
Symptoms in Adults
Adult horses and ponies with hypothyroidism will have major changes in their weight, their coats and their behavior. Their weight will go up, even if their appetites do not. Sometimes a rapid weight gain and loss of appetite can be symptoms of more serious conditions, so you need a vet to give your horse a proper diagnosis.
Horses and ponies with hypothyroidism also will be apathetic and not seem to want to do much of anything. They will often loose interest in play, sex or food. They will tire out far more easily than usual when worked. The horse may even seem to have forgotten even the most elementary of commands and may seem confused far more often than usual.
The coat will also be affected in horses with hypothyroidism. The hair will often get longer and will not shed at the appropriate time. The hair will also begin to feel rougher than usual. It will often stick up like a paintbrush rather than lay flat.
Treatment
Adult horses and ponies with hypothyroidism have a very good chance of surviving without treatment, but their quality of life will seriously be impaired. They are often given blood tests to check their iodine and thyroxin levels. If they are severely lacking in iodine, then it is added to the feed. If they are lacking in thyroxin, then they are given thyroxine. It can take up to three months to see any improvement in the horse.
Horses on thyroxine treatments need to have their blood checked regularly, so they don’t develop hyperthyroidism.
Additional References:
“The Complete Equine Veterinary Manual.” Marcy Parvord & Tony Pavord, BVSc, MRCVS. David & Charles; 2004
“Horse Owner’s Veteriary Handbook.” Thomas Gore, DVM, et al. Howell Book House; 2008.
“Hypothyroidism.” Douglas Novik, DVM. http://www.novickdvm.com/thyroid.htm
Kentucky Equine Reasearch. “Diagnosing Hypothyridsm in Horses.” Dr. Bryan Waldridge. http://www.ker.com/library/health/2010/07/diagnosing-hypothyroidism-in-horses.html
Reference:
- books.google.com/books?id=86yKpiLNLNkC&pg;=PA187&lpg;=PA187&dq;=pony+hypothyroidism&sour;
- www.lochlevenequine.co.uk/downloads/metabolic_syndrome.pdf
- www.equinechronicle.com/health/facts-and-myths-about-equine-hypothyroidism.html
