What are Physitis?
Developmental orthopedic disease (DOD) comprises a series of syndromes that causes irregular skeletal development in foals. Examples of such syndromes include angular limb deformities, osteochondritis, osteochondritis dessicans (OCD), cervical malformation, clubfoot, bone cysts, and physitis. For horse owners and breeders, developmental orthopedic disease may pose significant threats to their livelihoods, as well as the health of their companion animals.
First, it is important to understand that DOD is an umbrella phrase, so cases of DOD vary significant between equines. Symptoms, causes and outcomes vary from syndrome to syndrome, and from horse to horse. One of these syndromes, physitis, also called physeal dysplasia, is one of the least serious offshoots of DOD. Specifically, physitis refers to the inflammation of the growth plates in the long bones of a developing foal. In a foal’s skeletal system, the physis is the growth plate. In the case of bone development, which begins in the first month of gestation, a tiny system of cartilage slowly transforms into bone. This important developmental phase is called ossification. From the growth plate, the physis, the long bones in the limbs extend as the foal’s musculoskeletal system develops and matures. These long bones continue to lengthen over the course of the next 18 months. However, if this process goes awry, and the growth plate maladapts to the ordinary growth process of a healthy foal, physitis, a condition that causes deformities in the limbs of young foals, may occur.
At this time, no one factor has been isolated as a cause of syndromes such as physitis. Likewise, preventative steps to help breeders avoid syndromes of DOD have not been substantiated. The good news is that, in most cases, physitis recedes as the foal reaches maturity. Specifically, the physes close, enabling the foal to become a strong, clinically normal horse. Treatment is still important for the health of the foal because physitis is a painful condition.
Researchers do recommend a best-case scenario plan both to lessen the possibility of physitis and to treat foals born with limb deformity or irregularity. Mares must have proper nutrition during gestation and lactation, including a healthy balance of minerals, particularly copper and phosphorus. Proper diet (feeding small amounts of grain instead of one large meal), exercise and hoof trimming appear to give a foal the best chance to grow a healthy frame. Time is also part of this process. A veterinarian is an essential piece of this diagnostic process as physitis may indicate the presence of more serious DOD-related condition.
Physitis refers to the inflammation of the growth plates in the long bones of a maturing foal.
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Symptoms of Physitis in Horses
- Gait that appears stiff
- Reluctance to move
- Palpation presents pain
- Heat and swelling around growth plate
- Enlargement of the distal radius, tibia, and cannon bones
- The knee, hock, and fetlock joints may have an altered appearance
Causes of Physitis in Horses
- Over supplementation of calcium
- Mineral imbalances, particularly zinc, copper, manganese and iron
- Poor nutrition in mares
- Genetic predisposition (Quarter Horses and Paints)
- Conformational defects (faulty hoof growth)
- Compression of the growth plate
- Excessive exercise
- Injuries to growth plates and cartilage
- Major growth spurts
- Larger skeletal frames
- Feeding of grains and concentrates rather than hay
Diagnosis of Physitis in Horses
Diagnosis is made primarily based on clinical signs. Without imaging technology, a definitive diagnosis cannot be made. Radiographic examination has been considered the most reliable approach to diagnosing DOD and related syndromes, though more advanced, costly testing like MRI may be available. Imaging results can confirm the suspicion of physitis and can also indicate incomplete bone ossification and the presence of angular limb deformities.
Treatment of Physitis in Horses
A common treatment for less severe cases of physitis is non-treatment. Time plays a large role in the treatment process as many foals improve as they mature. Corrective shoeing and rest may be a conservative option. In more severe cases, surgery, such as transphyseal bridging, is an option. Pain relief in the form of anti-inflammatories, vitamin supplements, proper nutrition and exercise are all often recommended by a veterinarian. Corrective hoof trimming and shoeing is part of treatment and maintenance.
Recovery of Physitis in Horses
Veterinarians will direct horse owners to monitor the growth of foals by performing weekly height and weight checks. Growth spurts should be avoided if possible, so any signs of rapid growth, particularly in horses with a predisposition of such, may call for a food and exercise adjustment. Overfeeding appears to have a role in the development of physitis, as does the over-supplementation of vitamins and minerals.