By Dr. Amanda Wilson
It's a sight that can make your heart sink into your stomach: your horse is not willing to bear weight on a limb and is very painful and unwilling to move. This can be scary for you and for your horse and it is important to act quickly to identify the cause.
When you call your veterinarian, be prepared to give them the following information:
1. When was your horse last seen normal?
2. Can you observe any wounds in the skin on the affected leg? Are there any awkward angles or swellings you notice on the affected leg?
3. Have you given the horse any medications recently?
4. Can you see anything obvious (such as a nail) on the bottom of the foot when you lift it?
While your veterinarian is on their way, there are a few things you can do to prepare your horse for the exam and to assist your veterinarian in finding a diagnosis quickly. If the horse is able to walk and the distance is not very far, slowly move them to a stall or other dry, clean location away from other horses and close to a power source in the event that your horse needs X-rays. If the horse has to be moved any distance, it is best to keep them there and wait.
Make every effort to keep your horse calm and quiet while you wait. While it can be tempting to administer pain medications for your horse, it is advised to wait until your veterinarian can examine the horse because these medications can mask the location of the pain.
The possible causes for severe, sudden lameness
in a single limb are broken down into three categories:
Hoof abscess. This is the most common diagnosis for severe lameness and fortunately, the one with the best prognosis. Abscesses within the hoof start from a small piece of debris, rock, or other object working its way into the soft part of the sole and setting up an infection. This site of infection creates pressure around it and can be very painful. Your veterinarian can often open the abscess with a hoof knife and this usually makes the horse much more comfortable. Some abscesses are deep within the hoof and take some time to come to the surface. Sometimes the foot has to be bandaged or soaked to draw out the abscess, this can take a few days. Once the abscess has resolved, the horse can return to normal activity. A penetrating hoof wound such as that from an object like a nail can also cause similar signs.
Infection. An infection within a joint, tendon sheath, or bursa can cause severe, sudden lameness of one leg. These are most often associated with a penetrating wound that has punctured one or more of these structures. Often, the affected area is swollen and very warm to the touch. These infections require very early and aggressive treatment with antibiotics. The prognosis is very poor for resistant or chronic infections. Cellulitis (infection of the subcutaneous tissues) can also cause severe lameness.
Fracture. A bone fracture within a limb will immediately cause lameness. Sometimes these are evident with visual or hands-on exam but some can be very subtle and only identified with radiographs. Fractures are classified by their location and shape. Classification helps determine a treatment plan and the horse's prognosis for long-term soundness.
There are also several things that can cause severe, sudden lameness that affects more than one limb or area of the body: laminitis, tying up, neurologic disease, cellulitis/vasculitis. A discussion of these is beyond the scope of this article but these are important to mention.