It's normal for calcium to deposit in your dog's teeth and bones. Deposits elsewhere in the body are known as calcinosis circumscripta. These calcium deposits generally collect in your dog's subcutaneous tissue. Also known as tumoral calcinosis, these lumps usually aren't painful. If they open up, a chalky puslike substance might come out.
You might notice small lumps on your dog's footpads, over his joints or in his mouth. They might appear individually or in clusters. These deposits aren't necessarily just unsightly; they can ulcerate, causing bleeding and possible infection. Your veterinarian diagnoses the disorder via biopsy of the growth. In some cases, the deposits collect near a dog's spinal cord. You can't feel these growths, but affected dogs might experience neurological problems. Internal calcinosis circumscripta is diagnosed via X-ray or computed tomography.
Calcinosis circumscripta most often affects young large-breed dogs. In most cases, symptoms appear before the dog reaches his second birthday. While rare, the disorder appears to have a genetic basis. Affected breeds include the German shepherd, borzoi, Great Dane and English pointer. Large breeds are also prone to hygromas, or fluid-filled cavities developing on areas receiving pressure such as the elbow. It's not unusual for these hygromas to form calcium deposits.
While calcinosis cutis initially looks like calcinosis circumscripta, it appears on older dogs. It's more likely to appear as several calcium deposits rather than as a single lump. Calcinosis cutis usually results from adrenal cancer, but dogs treated with long-term steroid therapy for skin allergies and other issues are also vulnerable to the condition. Less frequently, diabetes or other types of cancer are the underlying cause of calcinosis cutis.
Treatment and Prognosis
Treatment for calcinosis circumscripta consists primarily of surgical removal of the growths. That's also true of calcinosis cutis. But if your dog has cancer, additional treatment including chemotherapy and radiation might be required. Many dogs do well after surgery, but the growths can recur. Sometimes the growths open up by themselves, with resulting unpleasant discharge. If your dog's growth opens up spontaneously, surgical removal of the tissue might aid healing. There's good news -- once an affected dog reaches the age of two, he's unlikely to develop new calcinosis circumscripta lumps. That's not true of calcinosis cutis.