Strange skin lesions? It could be calcinosis

An owner-described case study with photos documenting calcinosis circumscripta in dogs, a condition closely related to calcinosis cutis in dogs. In this 18-month old boxer, prolonged high-dose prednisone caused the calcinosis. Oozing white sores of calcium-phosphate first appeared on the underside of the tongue. They spread to bony prominences including shoulders and chest. See how it looked and hear firsthand experience in what an owner can do to heal it. Both kinds of calcinosis can be caused by steroids if the doses are high or if a dog is on the drugs for a long time.

This article documents my dog’s experience with the closely related condition called calcinosis circumscripta. All the information in this piece applies to both calcinosis cutis and calcinosis circumscripta. In our case, the condition developed as a side effect of prednisone in dogs. 

What is canine calcinosis cutis?

Rock hard skin lesions or subcutaneous lumps. They either stay beneath the skin or break open and ooze a chalky white substance. The ooze is calcium-phosphate mineral salts. It gives off a very distinctive but hard to describe odor.

Sometimes with calcinosis cutis in dogs, the plaques spread so extensively that it’s like the dog is armor-plated.


In our case, I noticed the calcinosis a few months after starting steroids. At first, the vet thought it was a pressure sore on one leg. Soon after, white lumps appeared on the underside of my dog’s tongue.

The vet was mystified. 

He was a specialist who regularly prescribed prednisolone. Calcinosis is well documented in the veterinary literature as a side effect of steroid medication. But the vet still didn’t recognize what it was. He gave antibiotics, taking a stab that it was some kind of mouth infection.

The antibiotics had no effect. The lumps spread. Eventually they covered the entire underside of the tongue. The vet did a biopsy. The pathology results came back identifying the lumps as calcium-phosphate. 

Finally, we had a diagnosis.


My dog was taking the steroids to treat meningitis. By the time we got off the drugs, he had more than a dozen calcinosis lumps all over his body. Mostly they were on “bony prominences” — in other words, places where the skin and bone are close together.

All up, the affected locations included:

  • underside of tongue
  • elbows
  • on the back
  • over bones of backside
  • on cheek bones
  • shoulders
  • hind legs
  • hocks
  • base of tail
  • chest
  • ribcage
  • paw pads

Most of the lumps were freely moveable under the skin. However, one of the shoulder lumps seemed affixed to the bone. 

Calcinosis cutis causes

Calcinosis cutis in dogs is due to endogenous (internally caused) or exogenous (caused by drugs) hyperadrenocorticism. 

Essentially this means there’s too much steroid in the body. When this happens spontaneously it’s known as Cushing’s disease. However, many dogs experience it as a result of steroids given to treat something else. 

Calcinosis cutis or calcinosis circumscripta?

My dog’s condition was what’s called calcinosis circumscripta, as opposed to the more common calcinosis cutis. 

Calcinosis circumscripta is distinguished by the distribution of the calcium-phosphate plaques as lumps in the subcutaneous tissue. The lumps typically form on bony prominences, the paw pads and on the bottom of the tongue.

By comparison, with calcinosis cutis, it’s more like a thin sheet of calcinosis in the dermis, usually open and weeping. Calcinosis cutis often starts at the base of the neck and spreads rapidly down the back.

Treatment for calcinosis cutis

The only way to actually cure calcinosis cutis or circumscripta is to address the excess of steroids. 

If it’s calcinosis cutis in dogs with Cushing’s, you have to control that underlying condition. When the calcinosis is iatrogenic (caused by drugs), you fix it by getting off the steroid medication, when possible.

Once you discontinue the drugs, the lumps will stop depositing. 

The condition then begins to resolve. It can take as long as five weeks or so to see the first improvement. Sometimes the lumps remain in the skin. Other times they can eventually disappear as the body very slowly resorbs them. Or the calcium-phosphate can push out through the skin. 

This is one of the reasons people say calcinosis “gets worse before it gets better”. 

This is what happened on the underside of Shiva’s tongue. It created those open bleeding sores. They became repeatedly infected and posed quite a challenge to manage.

How to manage calcinosis

Unfortunately, you have to wean off steroids painfully slowly. In the meantime, the only thing you can really do as calcinosis cutis treatment is supportive care. In other words, keep the area clean and prevent infection. Many owners use daily baths and poultices made with activated charcoal, which I’ll explain below. 

Veterinary treatments


Vets normally recommend DMSO for dogs with calcinosis. What is DMSO? Dimethyl Sulfoxide is a powerful solvent. It breaks down the mineral salts and sends them back into the bloodstream for elimination. If you take this route, do regular blood tests to monitor serum calcium levels. You’re supposed to wear gloves to apply and there’s some risk it can carry other substances that might happen to be on the skin through the skin barrier. So you need to be careful. All these warnings made it sound pretty heavy-duty to me. Some owners report seeing the site “smoke” when DMSO is applied. 

Calcinosis cutis dog natural treatment

Botanica cleansing wash

This Irish-made product boasts all natural ingredients and a large number of testimonials in all sorts of animals. It was gentle and very effective in keeping my dog’s lesions clean. We especially used it on Shiva’s tail area when it was an open sore. 

Activated charcoal for dogs

Buy it as a powder and carefully add water to make into a thick paste. Paint onto the affected area daily and leave for 15-20 minutes.

You can wrap the area in plastic which builds heat. Rinse off with water. Many owners of dogs with calcinosis cutis have found great success with activated charcoal. They feel it draws out the calcium-phosphate deposits and helps keep the area clean.

Beware the charcoal dust is very fine. Inhaling it (by activated carbon plant workers, for instance) can cause lung disease.

I tried activated charcoal for a while and it was gentle and may have been helping. The difficulty was that we lived in an apartment. The dust was depositing throughout the house. There was no way we weren’t inhaling it and so I discontinued it. It would be more viable if you have an outdoor area.

Nu-stock ointment

No bones about it, this ointment stinks! It’s used to treat a range of skin conditions in animals. Some owners have seen this help their dog’s calcinosis cutis. Pop on a t-shirt to prevent it smearing onto everything. 

Experimental options

A few small studies suggest oral aluminium hydroxide or oral charcoal absorbent can be used to treat calcinosis. To be honest, in that mad phase we’re you’re desperately clutching for solutions I bought both products (as well as DMSO) but never used any of them. I was concerned they might inadvertently cause other problems.


Some owners of dogs with calcinosis circumscripta have opted to have the lumps surgically removed once they’ve stopped depositing. I don’t know anyone who’s attempted calcinosis cutis removal. 

With calcinosis cutis, the skin sometimes remains blackened and scarred, but it doesn’t seem to bother the dogs. Usually the hair grows back.

In conclusion

If you suspect your dog has calcinosis, be sure to join this facebook group. Members have a lot of experience with the “cutis” version of the condition. 

The owner of Tyson the bulldog is also very generous in sharing her experiences using an activated charcoal bath for dogs with calcinosis cutis.

More reading

What prednisone does to your dog’s body

Can dogs eat bones?

Mucus in dog’s poop: When it’s a good sign

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