Osselets (Fetlock Arthritis) in Horses

Key Takeaways

Fetlock arthritis (aka “osselets”) in horses is inflammation of the fetlock joint and surrounding tissues. This condition is common in performance and racehorses. 

• Common signs of fetlock arthritis include reduced performance, lameness, joint swelling, and joint pain

• Fetlock arthritis is usually suggested based on a physical examination, including nerve and joint blocks, and is confirmed using X-rays

• Treatments for fetlock arthritis may include stall rest, cold therapy, anti-inflammatory drugs, joint injections, or surgical intervention

• Fetlock arthritis is a progressive disease with a variable prognosis that depends on the progression of disease, patient’s age, and response to treatment

A Closer Look: What is Osselets in Horses?

Fetlock arthritis is common in racehorses and high performance horses. Horses showing symptoms of osselets require prompt veterinary examination. It is important to diagnose and address arthritis early to prevent further joint damage. This disorder commonly affects either both front or both hind limbs.

Risk Factors

Symptoms of fetlock arthritis can vary in severity depending on the progression of disease. 

It is important to note that symptoms don’t always correlate to the severity of disease. Arthritis results in new bone formation around the joint. Symptoms will vary in location, presentation, and severity depending on the characteristics and progression of bone deposition in a given case. For example, a severely affected joint  may cause mild changes in performance  in one horse, whereas a mildly affected joint may result in a severe performance reduction in another horse.

Possible Causes

The fetlock is a highly mobile joint, and is subject to repeated stress during movement. The most common cause of fetlock arthritis is strain of the fetlock joint during training in young racehorses. Traumatic injury, such as fractures or osteochondrosis of the fetlock can also lead to fetlock arthritis.

Main Symptoms

The main symptoms of osselets are

Reduced performance • Joint pain • Skin over the joint feels warm • Swelling of the jointLameness

Testing and Diagnosis

Diagnosis begins with a physical examination, including a lameness exam and nerve or joint blocks. If fetlock arthritis is suspected, X-rays are required for diagnosis.

Steps to Recovery

If recognized early, the arthritis may be treated with stall or small pen rest for weeks to months. For more advanced disease, other possible treatments include:

• Applying cold packs to the affected area • Administration of anti-inflammatory drugs • Joint injections

• Arthroscopic removal of joint tissue • Surgical correction of the joint, including surgically fusing the joint 

Osteoarthritis is a progressive disease and cannot be definitively treated. Long-term treatment and preventative measures are key to management of this disease.  Fetlock arthritis has a variable prognosis regarding athletic performance. Outcome is dependent on the progression of disease, patient’s age, and response to treatment. Athletic horses often need a reduced workload or an alternative sport as their condition progresses. Some horses develop chronic lameness that requires retirement.

Prevention

Fetlock arthritis can be prevented by:

• Preventing trauma to the fetlock joint • Addressing joint abnormalities with appropriate treatments promptly

• Trimming feet appropriately

Is Osselets Common in Horses?

Fetlock arthritis is common in horses, particularly in racehorses and high performance horses.

Typical Treatment

• Stall rest • Cold compression • Anti-inflammatory drugs • Joint injections • Arthroscopy • Surgery

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