The word “osselet” means “little bone” in Latin. Osselets in horses is a repetitive stress injury usually associated with running and training. If left untreated, osselets in horses can lead to acute arthritis and bone growth limiting flexibility. Osselets can make it painful when the horse flexes the joint and may lead to lameness.
General Information about Osselets in Horses
Osselets in horses are caused by repetitive percussion occurring at the joint between the cannon bone and large pastern bone at the front of the fetlock. The stress of the impact with the ground causes inflammation at the joint. If left untreated and the condition worsens, the fibrous joint capsule may start to thicken. New bone growth may be triggered, which may limit the amount of flexion in the fetlock joint and can result in arthritis or lameness over time.
Osselets in horses do not have to be a permanently crippling condition. Prompt diagnosis and following the treatment plan prescribed by your veterinarian can result in resumption of normal activities.
What Causes Osselets in Horses
Horses with short, upright pasterns may be predisposed to developing osselets, as this type of pastern is not as efficient as a shock absorber. For other horses, chronic stress injury to the fetlock associated with the impact of running is the primary cause of osselets. Factors that can exacerbate the effects of the impact or cause uneven stresses to the fetlock include:
- Working out on hard or unforgiving surfaces;
- Poor shoe design or poor shoeing;
- Training on uneven and rugged terrain;
- Fatigue caused by extended running and training or rushed conditioning.
All of the above stressors lead to inflammation on the front of the fetlock joint. If left unchecked, the condition may worsen and the joint may become more and more irritated, eventually leading to lameness.
Treatment Options Available for Osselets in Horses
The first phase of treatment will focus on reducing the swelling and inflammation caused by the repetitive impact. For a horse diagnosed with osselets, the veterinarian will often first suggest limiting activity. Stall rest may be recommended for up to six weeks. It is important to follow your veterinarian’s recommendations and not resume activity too soon, as that may lead to a worsening condition.
The veterinarian may also recommend alternating hot and cold treatment of the area to reduce the swelling and inflammation of the fetlocks. Medicines that reduce swelling and inflammation may also be prescribed. A DMSO/cortisone wrap after activity may reduce the swelling.
Special shoes may be recommended for the patient that cushion the impact of the hoof on the ground. Shoes that prevent the over-extension of the fetlock joint may be in order as well. If your horse is predisposed to osselets, you may want to investigate shoes that can positively affect your horse’s step or gait.
Swimming may be recommended as a low-impact form of exercise that can develop the muscles of the leg and improve overall fitness without aggravating the condition. Strengthening of the muscles of the foreleg may improve the horse’s ability to handle uneven terrain and avoid undue fatigue of the joint due to missteps.
If bone spurs or bone fragments are diagnosed, these may need to be surgically removed
For patients with chronic osselets, who don’t respond to treatments, or who were not diagnosed and treated upon onset of the condition, further actions may be necessary. This may include cortisone injections or the injection of polysulfated glycosaminoglycans (PSGAGs). These may reduce the inflammation within the joint capsule and provide the patient with relief from discomfort.
For a horse with a predisposition to osselets or a horse with chronic osselets that does not respond to treatment, the only recourse may be a change to a career with less high-impact running.
Prevention of Osselets in Horses
The key to prevention of osselets is to identify predisposition towards developing osselets, and to be aware of high-impact activities that may lead to developing or aggravating the condition. For horses predisposed to developing osselets, special attention should be paid for symptoms of the condition. For them and for other horses, owners and trainers should be on the lookout for the following symptoms and behaviors:
- Hot swelling on the front of the fetlock joint
- An abnormally short, choppy gait
- Pain or soreness in and around the fetlock
- Stiffness of the fetlock joint
- “Pointing” one of the legs and trying to avoid putting weight on it
If diagnosed in the early stages of development and treated promptly, the condition may be resolved to the point where the horse can resume normal activities in a timely fashion. However, care should be taken to avoid rushing the horse back to normal activities, as this may result in recurring osselets.
Osselets in horses is a swelling on the front of the fetlock joint usually caused by the repetitive impact of running. Horses with short, upright pasterns may be predisposed to osselets.
The key to prevention and treatment is early detection of the symptoms and taking immediate action to reduce inflammation and long-term negative effects caused by the swelling. Working with a veterinarian to diagnose osselets and treat the symptoms can provide the patient with a speedy return to normal activities.