Carpal Hygroma in Horses

Horses spend a great deal of time on their feet so their legs need to be in good condition. This is especially true if you use your horse for work, racing, hunting, and riding. Some of the causes of carpal hygroma are poor bedding condition, trauma, and hitting the structure when jumping. If you see a growth anywhere on your horse’s leg, it is important to see a veterinarian that specializes in treating horses (equine veterinarian) to make sure it is not something serious or infected.

A carpal hygroma is a swelling or capsule in or near the knee filled with fluid caused by some kind of repeated trauma such as hitting knees on a fence or other hard objects. This is sometimes referred to as water on the knee because of the fluid and the fact that it is on the knee. While this swelling is usually painless, it can become large enough to cause lameness or pain. It is also possible for a carpal hygroma to become infected, so it should be treated whenever possible. There are several conditions that can be mistaken for carpal hygroma so it is best to get your horse seen by an equine veterinarian as soon as possible.

Some of the signs that your horse may have carpal hygroma include:

• Swelling over the dorsal area of the carpus
• Firm, capsule shaped lesion over the knee
• Warmth and redness in the affected area
• Slight limp or lameness of affected leg

In most cases, the carpal hygroma is caused by an injury or trauma to the affected limb. However, another cause may be inadequate bedding. Your horse needs between three and four inches minimum of proper bedding material. It can also happen when you are racing or jumping hurdles if your horse’s legs hit the structures you are jumping.

To diagnose carpal hygroma the veterinarian needs your horse’s history, job, and vaccination records, if possible. Also, the veterinarian has to do a physical examination including, but not limited to, your pet’s general health, behavior, condition, and conformation. This will be done from far away as you walk your horse and then up close for the detailed physical examination, which includes weight, height, body condition score, respirations, heart rate, body temperature, and blood pressure. You will be asked to trot your horse so the veterinarian can watch the muscle function, movement, and joint fluidity while in motion. A flexion test will be done next, which includes putting pressure on the affected joint for approximately two minutes and then having you trot again to see if there is pain causing any lameness. Then, a nerve block will be injected to numb the area before you go on another trot. This will help the veterinarian know if the carpal hygroma is causing any pain or lameness.

Additionally, blood tests will be performed such as a lactate dehydrogenase (LDH), creatine kinase (CK), chemistry panel, electrolyte and glucose levels, complete blood count (CBC), and a blood culture. The veterinarian will also need to get a bit of fluid from the hygroma to test for bacterial or fungal infection. Imaging is done last, which usually includes a contrast x-ray, ultrasound, and bone scan, but may also include a CT scan and MRI.

The veterinarian will use all of the information from the physical examination, laboratory tests, and imaging to create the best treatment plan for your horse. Some of the treatments used may include:

Aspiration

To help reduce the inflammation, the veterinarian will drain the fluid left in the carpal hygroma. A hypodermic needle will be used to remove any of the leftover fluid after shaving the hair and sterilizing the area. This is a fast and safe procedure that can be repeated if necessary.

Hydrotherapy

Soaking the leg in ice cold water is best for reducing the inflammation and easing the pain. Sometimes this will include immersing the limb in cold water for approximately 30-45 minutes. Then the veterinarian will drain more fluid and put the leg back in the water for another 30-45 minutes. Some other hydrotherapy treatments include static spas, water treadmills, and swimming.

Medication

The veterinarian may also decide to use NSAIDS (non-steroidal anti-inflammatories), corticosteroid injections, and a topical medication called diclofenac sodium liposomal cream to reduce inflammation and pain.

Arthroscopic Surgery

This joint surgery is usually done if the veterinarian suspects an infection or damage to the joint. The veterinarian will make three tiny incisions to insert the arthroscope and two small tools to remove particles or other debris that may be in the area from trauma or accident.

Prognosis is excellent for carpal hygroma with no lasting complications. If surgery was done, you will have to keep the wound clean and covered to reduce the chance of infection. The veterinarian will probably prescribe antibiotics just in case. Therapy is usually needed for several months.