Physitis (Epiphysitis)
metacarpal or metatarsal growth plate (with or without involvement of the proximal physis of the first phalanx). Older foals (8 to 24 months) may have signs of physitis at the physis of the distal radius.7 Less frequently, the distal physis of the tibia may be involved.
Physitis is characterized by firm swellings, which may be warm and painful upon palpation. Typically the swellings are medial due to increased weight bearing on this portion of the limb.7 Foals may or may not be lame. Changes radiographically include a sclerotic, roughened physis with an irregular metaphyseal shape.* 1 If the physitis continues, the growth plate may close prematurely, leading to an irreversible angular limb deformity (usually a varus deformity due to the decreased growth on the medial physis).7■ Diagnosis A diagnosis of physitis is usually made by appreciation of the clinical signs, including warm, sometimes painful, firm swellings in the above-mentioned locations. Physitis at the fetlock may appear to have an hourglass appearance if the proximal physis of the first phalanx is affected.7 A convex appearance just proximal to the distal tibial and radial physis may be seen early in the disease process.7 A quantitative method for detection of physitis was investigated in Thoroughbred foals.2 This method was based on the observation that when the physis is enlarged, there is more concavity of both the metaphysis and the ephiphysis. Results of this study show that epiphyseal concavity may indicate the degree of physeal swelling by using the maximum second derivative value of that contour.2 Radiographically, physitis is characterized by a growth plate that is irregularly thickened with sclerotic adjacent bone.2
■ Treatment and Prognosis Treatment of physitis should begin with management changes.
Special attention should be given to the nutrition of these foals and weanlings. Ensuring proper balance of minerals, especially calcium and phosphorus, and adequate amounts of trace minerals, such as copper and zinc, is necessary. Copper is required for successful crosslinking of collagen. When there is a copper deficiency, the cartilage matrix weakens and microfractures occur. Because mare's milk is very low in copper, foals rely on hepatic stores gained during the last trimester of gestation.5 One study showed that supplementation of mares with copper during gestation significantly reduced radiographic signs of physitis in their foals at 150 days of age. Supplementation of foals did not affect the incidence of physitis in the same study. Due to the results of this study, supplementation of mares during the second half of gestation with copper on farms with a high incidence of physitis may be beneficial in preventing physitis in their foals.9 A new supplement available to veterinarians, Leg Aide™, produced by Progressive Nutrition (Hopkins, Minn.), has anecdotally positive results for supplementing foals in rapid growth phases or with nutritional shortages.A general reduction in energy is needed to slow growth rates and when necessary to decrease body weight. Total concentrate should be 0.5 to 0.75 kg/100 kg body weight for nursing foals, 1 to 1.5 kg/100 kg body weight for weanlings, and 0.5 to 1 kg/100 kg body weight for yearlings. Varying degrees of discomfort are involved with physitis. For horses with very painful, warm physes, the judicious use of nonsteroidal antiinflammatory drugs (NSAIDs) is indicated. Exercise restriction, specifically stall rest, is indicated in affected horses. Without exercise restriction, these horses continue to load the physes, which may lead to permanent conformational changes, such as angular limb deformities. The prognosis for physitis is good for athleticism with early detection and treatment.
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- Physitis (Epiphysitis)
- REFERENCES
- Smith Bradford P., Van Metre David C., Pusterla Nicola (eds.). Large Animal Internal Medicine. Part 2. 6th edition. — Elsevier,2020. — 2279 p., 2020