Slipped Tendon (Perosis) in Geese: Hock Deformity and Leg Problems

Slipped tendon, often called perosis, is a developmental leg problem seen most often in growing goslings. The hock joint becomes enlarged and misshapen, the lower leg may twist or bow, and the gastrocnemius tendon can slide out of its normal position. When that happens, a goose may stand awkwardly, limp, or stop walking normally.

In poultry and waterfowl, perosis is usually tied to nutrition during rapid growth, not a contagious disease by itself. Merck Veterinary Manual describes perosis as a problem associated most classically with manganese deficiency, but choline, biotin, folic acid, niacin, and pyridoxine can also be involved. In ducks, geese, and turkeys, niacin needs are higher than in chicks, so feeding the wrong starter ration can contribute to leg trouble.

For pet parents, the big takeaway is that this is often a time-sensitive husbandry and nutrition problem. A mild early case may stabilize or improve with prompt veterinary guidance and diet correction. A severe or chronic case can leave a permanent deformity, ongoing pain, poor mobility, and reduced quality of life.

The most common cause is an imbalanced diet during growth. Merck notes that classic perosis in poultry is strongly associated with manganese deficiency, and can also occur with low choline, biotin, folic acid, niacin, or pyridoxine. In geese and other waterfowl, niacin deserves special attention because their needs are higher than those of chickens. Merck specifically notes that ducks, geese, and turkeys do well with about 55-70 mg/kg of feed for niacin, and that niacin deficiency can cause leg weakness and hock problems, although the Achilles tendon slips less often than in manganese- or choline-related perosis.

A common real-world trigger is feeding goslings a chick starter or unbalanced homemade ration instead of a properly formulated waterfowl or all-flock diet reviewed by your vet. Fast growth, poor feed storage, old vitamins in feed, and overcrowding can make the problem worse. Slippery flooring also adds strain to already weak legs and can worsen deformity.

Not every swollen hock is nutritional perosis. Trauma, infectious synovitis, septic arthritis, developmental bone disease, and other causes of lameness can look similar. That is why a hands-on exam matters, especially if only one bird is affected or the joint is hot, painful, or suddenly enlarged.

Your vet will usually start with a physical exam and diet history. They will look at the hock shape, leg alignment, ability to stand, body condition, growth compared with flockmates, and whether the tendon feels displaced. Feed type, age of the bird, supplements used, and whether the flock is eating chicken feed instead of waterfowl feed are all important clues.

In many cases, diagnosis is based on the combination of typical leg changes plus nutrition history. If the case is severe, unusual, or not improving, your vet may recommend radiographs to look for bone deformity or fracture, or testing to rule out infection. In flock situations, a feed review or feed analysis may be helpful when multiple goslings are affected.

If a bird dies or must be euthanized, a diagnostic necropsy can help confirm the problem and rule out infectious causes. This can be especially useful when several birds have leg issues, because treatment and prevention for a nutritional problem are very different from treatment for infectious joint disease.

Prevention starts with the right feed from day one. Goslings should be raised on a balanced ration appropriate for waterfowl or on a diet your vet has reviewed for growing geese. Avoid relying on chick starter alone unless your vet tells you exactly how to balance it, because waterfowl have different nutrient needs, especially for niacin support.

Good footing matters too. Use dry, non-slip bedding and avoid slick surfaces that force young birds' legs to slide outward. Keep feeders and waterers easy to reach, prevent overcrowding, and watch growth closely during the first weeks of life. A gosling that is smaller, wobblier, or slower than flockmates deserves prompt attention.

Store feed properly and replace stale feed regularly, since vitamin quality can decline over time. If you keep mixed flocks, review the ration with your vet rather than assuming one feed fits every species and age group. Early correction of diet and environment is the best way to reduce the risk of permanent hock deformity.