When Calcium Ends Up Where It Does Not Belong
Finding hard, gritty plaques on your dog's skin can be alarming, and rightfully so. Calcinosis cutis — the pathological deposition of calcium salts within the dermis and subcutis — is not a disease in itself but a cutaneous sign of an underlying metabolic or hormonal disturbance. In dogs, it most commonly signals hyperadrenocorticism (Cushing's disease), though its causes are broader than many owners realise. Understanding what drives calcium into the skin is the first step toward addressing it effectively.
The Underlying Causes
Calcium deposition in soft tissue is classified according to its mechanism. In dogs, the most clinically relevant categories are dystrophic and metastatic calcification, alongside a specific iatrogenic form.
Hyperadrenocorticism
Cushing's disease — whether pituitary-dependent or adrenal-dependent — is by far the most common cause of calcinosis cutis in dogs. Chronic excess of glucocorticoids alters calcium and phosphorus metabolism, damages connective tissue, and promotes mineralisation of the dermal collagen matrix. The skin becomes fragile and prone to secondary infection alongside the calcium deposits.
Iatrogenic Glucocorticoid Excess
Dogs receiving prolonged or high-dose steroid therapy can develop calcinosis cutis as a direct consequence of treatment. This is an important consideration in dogs managed long-term with corticosteroids for conditions such as immune-mediated disease or chronic allergy. The lesions are clinically indistinguishable from those seen with endogenous Cushing's disease.
Other Causes
- Chronic renal disease with secondary hyperphosphataemia and disturbed mineral balance
- Hypervitaminosis D, typically from excessive supplementation or ingestion of certain rodenticides
- Calcinosis circumscripta — a localised form often seen over pressure points or in the tongue of large-breed dogs, with no systemic cause identified
- Tissue damage and necrosis, where dystrophic calcification occurs in previously injured or inflamed tissue
Recognising Calcinosis Cutis
The classic presentation involves firm, white to yellow, gritty papules and plaques that may coalesce into larger mineralised areas. The deposits have a characteristic chalky or sandy texture when the overlying skin is ruptured. Common sites include the dorsal neck, axillae, groin, and ventral abdomen — regions of skin folds or areas subject to friction.
Secondary bacterial and yeast infections are extremely common, as the disrupted skin barrier and immunosuppression associated with glucocorticoid excess create ideal conditions for microbial colonisation. Affected areas are frequently erythematous, malodorous, and pruritic, though the calcinosis itself is not always painful unless infected.
In dogs with hyperadrenocorticism, calcinosis cutis rarely occurs in isolation. Other signs — pot-bellied appearance, polyuria, polydipsia, alopecia, muscle wasting, and thin skin — are typically present and provide important diagnostic context.
Diagnosis and Investigation
Skin biopsy is the most definitive way to confirm calcinosis cutis histologically, demonstrating basophilic mineralised deposits within the dermis. However, the more critical diagnostic step is identifying the underlying cause.
- Adrenal function testing (low-dose dexamethasone suppression test or ACTH stimulation test) to evaluate for Cushing's disease
- Full biochemistry panel including calcium, phosphorus, urea, and creatinine to assess renal function and mineral balance
- Vitamin D metabolite levels if hypervitaminosis D is suspected
- Thorough medication history to identify iatrogenic causes
- Abdominal ultrasound to evaluate the adrenal glands and kidneys
Cytology of affected skin areas helps characterise secondary infection and guide antimicrobial selection.
Treatment Approaches
Treating calcinosis cutis effectively requires addressing the root cause. Skin-directed therapies alone will not resolve mineralisation if the underlying hormonal or metabolic driver persists.
Addressing the Primary Cause
In pituitary-dependent hyperadrenocorticism, medical management with trilostane or mitotane reduces cortisol production. As cortisol levels normalise, calcinosis cutis frequently regresses over months, though resolution is slow and not always complete. In adrenal-dependent disease, surgical adrenalectomy may be recommended. For iatrogenic cases, tapering and discontinuing the offending steroid — wherever the underlying condition permits — is the priority.
Topical and Supportive Care
Dimethyl sulphoxide (DMSO) gel applied topically has been used to facilitate calcium resorption, with some evidence of benefit in canine calcinosis cutis. It should be used under veterinary supervision due to its potent skin penetration properties. Antiseptic shampoos and topical antimicrobials help manage secondary infection. In severe or refractory cases, surgical debridement of extensive mineralised plaques has been performed, though wound healing may be compromised by concurrent steroid effects on the skin.
Prognosis and Owner Expectations
Resolution of calcinosis cutis is achievable in many dogs once the underlying cause is controlled, but owners should be prepared for a prolonged course. Mineralised deposits may take six to twelve months to resorb significantly after hormonal control is achieved. Secondary infections require ongoing management during this period.
- Work with your veterinarian to identify and treat the underlying cause before focusing on the skin lesions
- Manage secondary bacterial and yeast infections promptly to reduce discomfort and prevent worsening
- Monitor calcium and phosphorus levels regularly where renal or metabolic causes are involved
- Be realistic about timelines — skin improvement lags behind hormonal control by months
- Report any worsening, new lesions, or signs of systemic illness to your vet without delay
Calcinosis cutis is one of the more striking dermatological manifestations of internal disease in dogs. With thorough investigation and commitment to long-term management, most affected dogs achieve meaningful improvement in skin comfort and quality of life.