What are Failure of Ossification of the Distal Tarsal Bones?
When the fetus is developing in utero, the bones are made up of cartilage only. As the fetus develops and is born, the bones slowly ossify over time. In some foals, the bones never completely harden and remain weak. This is not caused by anything specific except simple underdevelopment. It can cause the affected area to swell, have a deformity, cause pain, stiffness, and lameness. In most cases, the clinical symptoms are obvious, meaning you are able to begin treatment early on.
With braces or casts applied to offer your foal support, the bones are able to continue to develop and ossify before they become damaged or collapse entirely. In some cases, failure of ossification is not noticed until the horse begins to work, in this case, the therapies may be slightly altered but with the end goal being your horse not suffering from any long term deformity. Radiographs will be suggested to confirm the condition and then treatment implemented. If treated appropriately, prognosis of a recovery is good.
Failure of bone ossification most commonly occurs in neonatal foals. If you believe your horse is suffering from this condition, contact your veterinarian so treatment and therapies can be started immediately.
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Symptoms of Failure of Ossification of the Distal Tarsal Bones in Horses
Symptoms may include:
- Abnormal tarsal bone conformation
- Osteoarthritis of the distal tarsal joint
- Tarsal bone appears smaller than it should be
- Flexion deformity of the hock
- Hock swelling
- Stiffness of the hind limbs
- Abnormal angle in the affected part of the limb
Failure of ossification of bones is most often seen in neonatal foals, however, it can affect older horses as well. Sometimes the condition is not caught until the horse is older and is put to work. When it affects older horses, it typically comes with secondary joint disease and collapse of joint spaces. The same condition is affecting each horse in this scenario, it is just the difference in age that sets them apart.
Causes of Failure of Ossification of the Distal Tarsal Bones in Horses
In a developing foal, ossification begins in the center and at each end of long bone. Eventually, it all ossifies and unites and results in a formed bone. When ossification remains incomplete, it leaves the bone weak and vulnerable. The un-ossified bone is unable to support the weight of the foal which can then lead to collapse and injury.
Diagnosis of Failure of Ossification of the Distal Tarsal Bones in Horses
In many cases, symptoms of abnormal bone ossification can be seen as the foal is developing. His clinical symptoms may not be obvious at first, but then the more he is up and active, the more pronounced his symptoms will become. To confirm his condition, the veterinarian will want to take a radiograph of the affected limb and the joints above and below it.
She will want to complete her physical exam entirely to ensure there are no other areas affected by the same or similar condition. She may also recommend routine blood work to see if the foal needs any other medical assistance to develop properly. A complete blood count and chemistry panel will give the veterinarian information on how the organs are functioning, how the blood is supporting the body, and if he is fighting off any type of infection.
Treatment of Failure of Ossification of the Distal Tarsal Bones in Horses
One of the most important things when it comes to treatment of failure of ossification in your horse is early diagnosis of treatment. The earlier you catch the condition, the less likely your horse will have of experiencing the crushing of the bone and progressive osteoarthritis. Cylinder tube casts can be utilized immediately to protect the immature bones with good results.
Stall rest is very important for newborn foals with failure of bone ossification but should not exceed one month. A balanced diet is also very important when it comes to the foal’s recovery. Your veterinarian may suggest diet supplements to assist with bone development and health. Just like with humans, sometimes we need a few extra nutrients in order to grow and heal.
Recovery of Failure of Ossification of the Distal Tarsal Bones in Horses
If caught early on and treatment started immediately, the prognosis of a recovery is good. As long as you provide the horse with the support his developing bones need, he should recover without any long term side effects. However, if it is left untreated, it can lead to the foal being unable to support itself to nurse, limb deformities, chronic arthritis, lameness, pain and permanent abnormality.