CONDITION

Calcinosis Circumscripta

Calcinosis circumscripta is a condition in which calcium salts are deposited in the soft tissues beneath the skin, forming one or more firm lumps that can sometimes ulcerate and discharge a chalky white material. The deposits most commonly appear on the hind feet and lower limbs, the tongue, or over bony pressure points such as the elbow, though they can occur at other sites. Owners often notice a single hard swelling that has developed slowly, or they may find a wound that will not heal and is leaking a gritty white paste. The condition is seen most often in young, large-breed dogs, particularly German Shepherds, though it can occur in other breeds and occasionally in cats. The cause in most cases is not known; the deposits form without any apparent trigger, and the rest of the animal is usually well. This page explores what an owner may observe, what is understood about how these deposits form, the investigations that help clarify the picture, and the approaches that exist for managing them.

Why this matters now

Signals & patterns

Early signals

Later signals

Click to read about the biological mechanisms

How this is usually investigated

Options & trade-offs

Related conditions

Calcinosis Cutis

Calcinosis cutis describes a broader pattern of calcium deposition in the skin that can occur across different parts of the body, often associated with underlying metabolic or hormonal disturbances, whereas calcinosis circumscripta typically presents as isolated deposits without such systemic triggers. The two conditions share the core mechanism of calcium salt accumulation in soft tissue but differ in distribution and context.

Sterile Nodular Panniculitis

Sterile nodular panniculitis can present as firm lumps in the skin that may be considered during evaluation of subcutaneous masses, though the inflammation in panniculitis targets the fat layer itself rather than involving calcium deposition. Both conditions may occasionally ulcerate and discharge material, which can make them difficult to distinguish on initial examination alone.

Canine Parvovirus

Histiocytoma is a common benign skin growth in young dogs that presents as a firm nodule, and may be considered when evaluating a solitary lump in a young, large-breed dog—the same demographic pattern often seen with calcinosis circumscripta. The two can sometimes be distinguished by texture, as calcinosis deposits tend to feel harder or grittier beneath the skin.

Lipomas

Lipomas are soft, moveable fatty lumps commonly found in dogs and may enter the differential diagnosis when an owner notices a subcutaneous mass, though they lack the firm, gritty texture characteristic of calcium deposits. Both are generally benign findings that may remain stable or grow slowly over time.

Mast Cell Tumours

Mast cell tumours are among the more common skin growths in dogs and can present as firm nodules that might prompt consideration alongside other causes of discrete lumps. Unlike calcinosis circumscripta, mast cell tumours arise from immune cells and carry the potential for more variable biological behaviour.