Rickets in Sheep: Weak Bones, Bent Legs, and Mineral Deficiency

Rickets is a metabolic bone disease of young, growing sheep. It happens when developing bones cannot mineralize normally, most often because the lamb is not getting enough usable vitamin D, phosphorus, calcium, or the right calcium-to-phosphorus balance. The result is soft, weak bone near the growth plates, especially in the legs.

In sheep, rickets is most often discussed in lambs with weak bones, enlarged joints, lameness, and bent legs. Merck notes that rickets affects growing animals and impairs normal endochondral ossification at the growth plate. In ruminants, activated vitamin D deficiency is commonly linked to limited sunlight exposure and sometimes dietary phosphorus deficiency. Cornell also lists rickets in sheep as a disease of the young caused by calcium, phosphorus, and vitamin D imbalances.

Some lambs recover well when the problem is found early and the feeding program is corrected. If the condition is advanced, however, bone deformities may not fully reverse. That is why it helps to involve your vet early, especially if several lambs in a group are growing poorly or walking abnormally.

Rickets in sheep is usually caused by a problem with bone mineral nutrition, not an infection. The main drivers are too little vitamin D, too little phosphorus, too little calcium, or an imbalanced calcium-to-phosphorus ratio. Merck notes that in ruminants, vitamin D deficiency is generally tied to lack of sunlight exposure and, to a lesser extent, dietary phosphorus deficiency.

Management plays a big role. Lambs kept indoors for long periods, especially fast-growing lambs in confinement, may not get enough ultraviolet light to support vitamin D production. Ohio State and Virginia Tech extension sources note that sheep housed indoors for more than a few weeks may need dietary vitamin D support, while sheep on pasture usually get enough from sunlight and normal forage.

Diet quality matters too. Mature brown forage, low-quality hay, and roughage-heavy diets can be low in phosphorus, especially when little grain or mineral supplementation is provided. Montana State notes that mature pasture and range forage is often phosphorus-deficient, and that a 2:1 calcium-to-phosphorus ratio is ideal for most sheep rations. Sheep fed the wrong mineral product, inconsistent supplements, or cattle minerals can also run into serious nutrition problems.

Rarely, inherited forms of rickets have been reported in sheep, including Corriedale sheep. If one lamb is affected, nutrition is the first concern. If multiple well-managed lambs from related lines are affected despite a balanced ration, your vet may consider a genetic contribution.

Your vet will start with a history and physical exam, including age, growth rate, housing, access to sunlight, forage type, grain intake, and the exact mineral or vitamin products being used. This history is important because rickets often reflects a flock feeding issue, not only an individual lamb problem.

According to Merck, the most reliable in vivo test is radiography of large bones and joints. X-rays may show widened, irregular growth plates, lower bone density, and changes consistent with poor mineralization. Bloodwork can also help. Merck notes that alkaline phosphatase is often increased, while calcium, phosphorus, and vitamin D values may be altered depending on the underlying cause.

Your vet may recommend serum chemistry, calcium and phosphorus testing, and sometimes a broader nutrition review of the ration or mineral tag. In some cases, feed analysis is useful, especially if several lambs are affected. Other conditions can mimic weak or crooked legs, including trauma, white muscle disease, congenital limb deformities, and other metabolic bone disorders, so diagnosis should not rely on appearance alone.

Prevention starts with a balanced sheep ration and a sheep-specific mineral program. Make sure growing lambs receive enough calcium, phosphorus, and vitamins, and that the calcium-to-phosphorus ratio is appropriate for the feeding system. Extension guidance for sheep commonly targets about 2:1 calcium to phosphorus in most rations, while mature forage diets may need added phosphorus.

Sunlight and forage type matter. Sheep on pasture usually make enough vitamin D from sun exposure, but lambs raised indoors or in confinement may need dietary vitamin D support. Sun-cured forage also contributes vitamin D activity. If lambs are housed inside for weeks at a time, ask your vet and nutrition advisor to review the ration before problems appear.

Use only sheep-formulated minerals unless your vet or nutritionist directs otherwise. Cattle minerals can be dangerous for sheep because of copper content, and homemade supplementation can create new imbalances. Monitor mineral intake, growth, and gait in young lambs, especially during winter housing, rapid growth phases, or when forage quality changes.

If one lamb develops suspicious leg changes, review the whole group right away. Early flock-level correction is often the most practical way to prevent more cases.