What are Exotoses of the Metatarsal Bones?
Exostoses of the metatarsal bones in horses is a common skeletal problem also known as splints and doesn’t always exhibit itself in lameness. Sometimes, the affected horse may not even display any symptoms at all. The second and fourth metatarsals of the horse are two splint bones which run down the sides of the cannon bone (third metatarsal and the largest bone in the limb) from the knee to about two-thirds of the length of the cannon bone, ending above the ankle. The term splints usually refers to the condition caused by the inflammation of an injury to the splint or metatarsal bones of the limb.
The definition of exostoses is basically a benign growth on the surface of a bone or a tooth, also known as a bone spur. The benign growth, in this case, would be located on one of the metatarsal bones of one of your horse’s limbs.
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Symptoms of Exotoses of the Metatarsal Bones in Horses
If your horse is suffering from exostoses of the metatarsals, he may or may not display symptoms that you will notice. If there are symptoms, however, here are some that you may see:
- This condition is most frequently seen in two-year olds who are beginning the training process
- Lameness, if it occurs, will be noted when the equine is working or when at a trot or sometime after the activity has been discontinued - usually not long after the activity is done
- Lameness may be constant or intermittent
- Feeling along the cannon bone will likely reveal places of inflammation which may be swollen to varying degrees to which the horse may display a pained response when pressure is applied
- You may visually observe swelling in one or more limbs
The types of disorders of the metatarsals in the horse basically come down to three categories:
- Bucked shins - A condition that refers to the inflammation and eventual elevating or tearing away of the periosteum (tissue that covers bones or attaches metatarsals to cannon bone) from the front of the cannon bone in the limb
- Exostoses of the metatarsals - A condition in which benign growths form on the surfaces of bones
- Various types of fractures of the metatarsals - This includes open fractures as well as closed fractures
Causes of Exotoses of the Metatarsal Bones in Horses
These exostoses of the metatarsals (splints) are most commonly found, but not limited to, in younger horses. These benign growths can be found at injury sites or at stress points and are frequently the result of previous injuries. They can also be caused by unequal pressure or stress applied to a joint, soft tissue attachment or bone. It is pretty much a natural process for the body to form new bony tissue at the site of a break or fracture and thus, the formation of the exostosis or benign bony growth is the normal process of the body healing the hurt, whether resulting from an injury or from strain. These are common maladies of the equine and are successfully treated in most cases.
Diagnosis of Exotoses of the Metatarsal Bones in Horses
To diagnose the reason for the suspected lameness or discomfort, the affected limb should be imaged radiographically to ascertain if there are fractures involved. Previous fracture sites can be the harbinger of potential exostoses of the metatarsals. Since the body will naturally heal the hurt, it is important to get to the root cause of the growth. The growth may be smaller or of a larger size and may not be tender to the touch or palpation upon physical examination.
Radiography will reveal the presence (or not) of possible fractures, or even microfractures, as there can be multiple sites at which the exostoses is taking place. This will also show any splint bone fragments which may be around the injury site. Radiography will help to ascertain if the cause of the growth is inflammatory in nature versus the result of fracture, regardless of size or type. These tests, along with the physical examination, will enable your veterinary professional to develop a treatment plan to get your horse back to work as quickly and safely as possible.
Treatment of Exotoses of the Metatarsal Bones in Horses
For those horses who are having symptoms, the general treatment will likely be some type of cold treatment (ice packs, cold hosing), bandaging the limb, and administering non-steroidal anti-inflammatory medications. For some horses, injecting corticosteroids in the areas around the exostosis has been found to be of some benefit. Surgical removal of the exostoses which are causing significant pain and discomfort is also an option under certain conditions.
Many microfractures will heal nicely without any treatment. Rest is a major recommendation given by veterinary professionals for a minimum of 30 days and a recommendation for keeping the horse on soft ground will likely go along with the recommendation for rest. This will reduce the pressure being placed on the injury so the healing process can take place more naturally and appropriately. Keep in mind that many splint injuries can heal quite nicely on their own without any real treatment.
Recovery of Exotoses of the Metatarsal Bones in Horses
The prognosis for a horse suffering from exostoses of the metatarsal bones is very good. Recovery should be complete provided the medically recommended regimen is followed. Recovery for those horses who exostosis or bony growth is very large and interferes with the action and function of the knee, or interferes with the attachment of the suspensory ligaments, surgical intervention may be called for to remedy this very tough situation.
For those very young horses in which you suspect problems with exostoses, begin as early as possible with good nutrition and attention to stress on the bones to build up the density as the foal grows. Then, when the foal is old enough, begin training that incorporates extended work in the areas of trot, gallop and speed and increase in a step-by-step fashion.