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Vaccinations important for health of young horses

by Wyoming Livestock Roundup

Young horses can be particularly susceptible to disease making it important for them to receive timely vaccinations, according to Cynthia MacKenzie,a senior equine technical services veterinarian for Merck Animal Health. MacKenzie and Alan Ruggles of Rood and Riddle Equine Hospital in Lexington, Ky., addressed questions related to caring for young horses during a young horse care webinar sponsored by

“Vaccinations are a critical component of protecting young horses from any disease,” MacKenzie explained. “Vaccines help the horse develop its immune system and the memory of the immune system which affect the horse its entire life. Vaccines help the horse build up protective responses to future pathogens.”

Because each area of the country has different disease issues, MacKenzie stopped short of recommending a vaccination program, explaining it is important to consult a veterinarian to develop a customized vaccination program for the owner’s particular operation. This program should take into account the number of mares with foals, if the horses remain on the farm or travel, and the part of the country the operation is located. 

“Foals can receive vaccinations at four to six months,” she said, recommending that foals receive a three dose series of vaccines to protect against infectious upper respiratory infections like equine influenza, Rhinitis and equine herpes. 

The equine influenza vaccine may not be administered until the foal is closer to six months because of the antibodies the foal has in its system from the mare, she explained. 

She also encouraged horse owners to have a good deworming program in place. If the foal develops a potbelly that looks distended, it could be one of the first signs the foal is carrying a load of worms. If the foal is clear of worms, MacKenzie said to look at the nutrition program. 

“Foals can not digest hay as effective as an older horse,” she explained. “They may need a higher quality grass hay or alfalfa.”

Foals should receive 1.5 pounds per day per 100 pounds of body weight, which can be adjusted if the foal has access to good quality and quantity of pasture. 

“The idea is to support growth and nutrition of the foal without making them fat from eating too many calories,” she said. 

“If weanlings or yearlings are going to a show, I would restrict the hay and feed them a good quality alfalfa or grass hay, or a complete feed to keep the belly off, and keep them growing at a moderate rate,” she added.

Gayle Smith is a correspondent for the Wyoming Livestock Roundup. Send comments on this article to

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