Perosis in Turkeys: Slipped Tendons and Leg Deformities
- Perosis is a leg development problem in young turkeys, most often linked to nutrient imbalance, especially low manganese or choline in the diet.
- Common signs include swollen hocks, bowed or twisted legs, poor growth, trouble standing, and in more severe cases a slipped Achilles-type tendon.
- Early cases may improve if your vet confirms the cause and the ration is corrected quickly. Long-standing deformities are less likely to fully reverse.
- See your vet promptly if a poult cannot stand, is being trampled, stops eating, or several birds in the flock show similar leg changes.
What Is Perosis in Turkeys?
Perosis is a developmental leg disorder seen most often in growing poults. Pet parents may hear it called slipped tendon, but that phrase only describes one part of the problem. In perosis, the hock area and nearby leg bones do not form normally, so the leg starts to rotate, bow, or flatten. In more advanced cases, the gastrocnemius tendon can slip out of place.
This condition is usually tied to nutrition rather than injury alone. In poultry medicine, perosis is classically associated with manganese deficiency and can also occur with choline deficiency. Similar-looking leg problems can happen with other nutrient shortages, including niacin deficiency, so a careful exam matters.
Turkeys are especially important to watch during rapid growth. A poult with mild changes may only look awkward or reluctant to walk at first. If the problem continues, the bird may become lame, spend more time sitting, lose access to feed and water, and develop permanent deformity.
Symptoms of Perosis in Turkeys
- Swelling or puffiness around the hock joint
- Flattened, enlarged, or misshapen hock
- Bowed, twisted, or rotated legs
- Lameness or reluctance to walk
- Poor growth or smaller size than flockmates
- Tendon slipping from the hock condyles
- Unable to stand or repeatedly falling
Mild cases can be easy to miss at first, especially in a fast-growing group of poults. Watch for birds that sit more than others, walk stiffly, or have hocks that look puffy or uneven. Compare both legs and compare the bird with healthy flockmates.
See your vet sooner rather than later if the leg looks twisted, the tendon appears displaced, the bird is losing weight, or more than one turkey is affected. Flock-level patterns often point to a feed or management problem that needs quick correction.
What Causes Perosis in Turkeys?
The most recognized cause of perosis in turkeys is dietary manganese deficiency during growth. Manganese is important for normal cartilage and bone formation. When growing poults do not get enough, the hock and leg bones can develop abnormally, leading to joint enlargement, twisting, shortening of the leg bones, and tendon displacement.
Choline deficiency can also cause classic perosis changes in chicks and poults. In these birds, the hock may first become slightly puffy, then the metatarsus rotates and the leg can no longer support weight well. The tendon may eventually slip from its normal position.
Perosis is not tied to one nutrient alone. Similar leg deformities can also be seen with other nutritional problems, including niacin deficiency, which is especially important in turkeys because they are more sensitive than chickens. With niacin deficiency, the legs may bow and the hock may enlarge, but the Achilles tendon is less likely to slip.
Feed formulation errors, old or poorly stored feed, homemade rations, incorrect supplementation, or feeding a diet meant for another species or age group can all raise risk. High calcium or phosphorus intake may also worsen manganese-related problems by reducing manganese absorption.
How Is Perosis in Turkeys Diagnosed?
Your vet usually starts with a hands-on exam and a close look at the flock history. They will ask the bird's age, growth rate, what feed is being used, whether the ration was recently changed, how long signs have been present, and whether multiple poults are affected. That history is often one of the biggest clues.
On exam, your vet looks for hock swelling, rotation of the metatarsus, bowing of the legs, poor body condition, and whether the tendon has slipped from its condyles. Because several conditions can mimic perosis, diagnosis also means ruling out other causes of lameness, including niacin deficiency, infectious synovitis, trauma, and less common developmental or hatch-related problems.
In some cases, your vet may recommend radiographs, feed review, or lab support. If several birds are affected or a bird dies, flock-level diagnostics or necropsy through a veterinary diagnostic lab can help confirm whether the problem is nutritional, infectious, or mixed. That matters because treatment and prevention plans are different for each cause.
Treatment Options for Perosis in Turkeys
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Office or farm-call exam focused on gait, hock alignment, and body condition
- Immediate review of the current turkey ration, treats, supplements, and storage conditions
- Switch to a complete, age-appropriate commercial turkey starter or grower feed if your vet agrees
- Supportive nursing care such as easy access to feed and water, softer footing, and separation from stronger flockmates if needed
Recommended Standard Treatment
- Veterinary exam plus targeted differential diagnosis for nutritional, infectious, and traumatic causes
- Guided correction of the ration and supplement plan based on age and flock use
- Radiographs or focused imaging if the leg is severely deformed or the diagnosis is unclear
- Discussion of humane quality-of-life decisions for birds with severe tendon displacement or permanent inability to stand
Advanced / Critical Care
- Comprehensive flock investigation with feed analysis, diagnostic lab submission, or necropsy when indicated
- Advanced imaging or referral-level avian evaluation for complex lameness cases
- Testing for infectious differentials such as mycoplasma-associated synovitis when the history or exam suggests it
- Intensive supportive care planning for valuable breeding or companion birds, including repeated rechecks
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Perosis in Turkeys
Bring these questions to your vet appointment to get the most out of your visit.
- Does this look most consistent with perosis, niacin deficiency, trauma, or an infectious joint problem?
- Is the tendon actually slipped, or are we seeing early hock and bone changes that may still improve?
- Is our current turkey feed appropriate for this bird's age and growth stage?
- Should we change the whole flock's ration right away, and if so, to what type of feed?
- Do you recommend radiographs, feed analysis, or diagnostic lab testing in this case?
- If several poults are affected, should we submit a bird for necropsy to confirm the cause?
- What signs would mean this bird's quality of life is poor enough that humane euthanasia should be discussed?
- What changes to footing, feeder height, and housing would help reduce stress on the legs while we address the cause?
How to Prevent Perosis in Turkeys
Prevention starts with feeding a complete commercial turkey ration made for the bird's age and purpose. Turkeys grow quickly and have different nutrient needs than chickens, ducks, or mixed-flock birds. Using the wrong feed, diluting feed with too many extras, or relying on homemade diets without veterinary nutrition guidance can increase the risk of leg problems.
Store feed in a cool, dry place and replace stale or damaged bags. If you use supplements, do so only with your vet's guidance. Adding nutrients without a plan can create new imbalances instead of fixing the original one.
Watch young poults closely during the first weeks of growth. Early hock puffiness, awkward walking, or slower growth than flockmates should prompt a fast review of feed and housing. Good footing, easy access to feed and water, and avoiding overcrowding also help reduce stress on developing legs.
If one bird develops suspected perosis, think flock-wide. Because nutritional problems often affect more than one poult, early correction can protect the rest of the group and may prevent mild cases from becoming permanent.