Horse Drops Feed

Q:My horse has an unusual problem. A dentist has worked on him, but he still drops his oats while trying to eat them. Now he is being fed pellets. I do not know if grazing is a problem for him, but he did drop in weight during the winter. Do you have any idea what the problem might be? If his teeth were in need of treatment for a long period of time, could he have developed a bad way of eating to avoid pain?

Colin, via e-mail

A: There are many reasons that a horse might drop feed, and while I can't give you a definitive diagnosis on the information that you have provided, I can offer advice on how to go about understanding why your horse may exhibit these clinical signs.

It's important to first figure out a few key pieces of information, and they are as follows: How old is the horse? A young horse dropping feed is different from an old horse dropping feed. Young horses can drop feed because their teeth have sharp points or retained caps, and they can have dental complications as their permanent teeth erupt (See page 58 of the March 2011 issue for an illustration of how teeth erupt). Older horses often drop feed because of dental malocclusion or an uneven bite, sharp points, or missing or loose teeth.

Watching your horse eat is a good place to start to make sure the horse can actually prehend (bite) the feed, get it into the mouth, and then chew it correctly. It is important to notice if the horse drops the same amount of feed now that he is eating pellets as he was when he was eating oats, and if he is able to eat his hay or is leaving it balled up in the feed bucket or stall.

Has the horse had a thorough oral exam performed by a veterinarian comfortable with dentistry? A thorough oral exam involves placement of a mouth speculum with visual and tactile inspection of all teeth in the mouth. However, without a full exam, it is hard to say whether the horse has any oral pain or may have an abnormality of his mouth, preventing him from fully chewing his food.

You asked if your horse could have developed poor eating habits if he were in need of dental care for a long period of time. The answer is yes. Severe dental abnormalities or malalignment could have caused him to develop an abnormal chewing pattern from pain or mechanical limitations. Such abnormalities may include a shear mouth, a wave mouth, infected tooth roots, sharp points, and other uncomfortable conditions.

The problem may not be dental, and a thorough physical and neurologic exam is the next step in this diagnostic process. Horses have two temporomandibular joints (TMJ), one on either side of their mandible (lower jaw). This joint allows the mandible to move up and down and side to side, facilitating movement of the jaw and chewing. If this joint becomes inflamed or sore, it can affect a horse's ability to eat. Other things that can cause difficulty chewing and can be observed on a physical exam include swelling or abnormalities of the face and neck. If a horse has had any trauma recently to his head, it could also cause him to drop feed and chew abnormally. A neurologic exam, in particular an exam of the cranial nerves, will allow evaluation of a horse's ability to prehend his food, move it back into his mouth, and then swallow it properly. After thorough evaluation, a veterinarian should be able to recommend further diagnostics or a plan of action.

So there is not a simple answer to this seemingly simple question. In order to determine the reason your horse is dropping feed, I recommend a veterinarian perform an oral exam, a complete physical, and a cranial nerve exam. If nothing significant is discovered, then further diagnostics can be performed. These include skull radiographs to evaluate tooth roots and the sinuses, radiographs and ultrasound examination of the TMJs, or a joint aspirate (fluid sampling of the TMJs via aspirating with a needle).

In horses routine dental care is extremely important, and any sign of dental disease or problems warrants an exam by an experienced veterinarian or licensed equine dental technician. In this case, there is not enough information provided to make an accurate diagnosis and further evaluation is recommended.

About the Author

Julia Wolfe, DVM, Dipl. ABVP

Julia Wolfe, DVM, Dipl. ABVP, is a veterinarian with the University of Pennsylvania's New Bolton Center.

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