Physitis in Young Horses

March 22, 2010 (published) | November 14, 2016 (revised)

Physitis is a condition that develops in foals who are between 3 and 6 months of age.  It is an inflammation of the growth plate at the ends of the long bones, and it usually occurs just above the knee, fetlock, or hock.  These areas become swollen and are painful, causing lameness of varying degrees.  The problem is a nutritional one in which growing foals are overfed and are getting too much energy in their diet.  It is common in foals grazing lush pasture or those being fed large amounts of grain to encourage rapid growth.  Diagnosis of the condition is suspected due to clinical signs of swelling above the joints but must be confirmed by X-rays to make sure the foal doesn’t have a fracture. 

If physitis is diagnosed, a diet analysis is required to make sure the foal is getting the correct amount of energy – enough, but not too much energy.  To reduce energy, some of these foals will need to be weaned if they are nursing mares that produce a lot of milk.  The hay may need to be changed from alfalfa to a good quality grass hay, and it may be necessary to replace high energy concentrates with a ration balancer.  Some breeders may be reluctant to decrease nutrition as they desire a certain size foal for a show or sale.  However, if a foal is lame, shows are not an option anyway. 

Regardless, we have to do what is best for the horse but we do not want to starve the foals so it is best to place them on a balanced diet with supplemental vitamins and minerals if necessary.  Also, confining these foals is critical as they are in pain and without confinement, these young foals will follow the mare all over the pasture, causing more pain and increasing the inflammation.

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