Canine Histiocytomas: Causes and Treatment

Histiocyte cells are part of the skin’s immune system. These white blood cells respond to bacteria and viruses by increasing in number and, in the process, can produce an abnormal amount of tissue in a short amount of time.

These cells can also be found in the nose, stomach, lungs, and intestines, but they are predominantly on the skin’s surface.

A histiocytoma presents as a small round growth that is usually pink or red in color. There is seldom more than one. They’re not painful on their own, but they can be irritating, depending on the location. Tumors found on the foot can produce a limp. Histiocytomas found in the ear can cause head-shaking.

While any virus or infection can cause a histiocytoma, no particular virus or germ has ever been identified as a cause. Dogs cannot easily spread it to each other, nor to other pets or humans.

There is speculation that they’re connected to growth spurts since it’s predominantly a puppy and young dog issue. There have also been some cases that originated following an injury that broke the skin, such as a tick bite.

These tumors are considered benign and often disappear on their own within 3 months. A histiocytoma only requires removal if it blisters or grows in an area that causes your dog distress, such as between the toes. These growths can be itchy, and dogs can blister them by licking or scratching, causing a secondary infection — or even the possibility of it turning cancerous.

The short answer is no. If the growth does not blister or become infected, you don’t have to have it removed. However, if it starts oozing, becomes irritated, is hot to the touch, or if the tumor doesn’t go away in 3 months, you need to take your dog to your veterinarian.

There are some treatments for histiocytomas you can try at home. Applying a saltwater solution to the site helps prevent infection, and cortisone cream can also help with the inflammation. However, you’ll need to monitor your dog very closely to prevent them from licking, scratching, or biting the tumor, which can result in the vet bill you were trying to avoid.

There are malignant tumors that can mimic a histiocytoma, so it’s always advisable to get any growth checked out by your vet. There are two biopsy methods: One removes the entire tumor, and the other takes sample cells. For the first method, the area is numbed, the growth is snipped off, a few stitches are put in, and the tissue is sent off to be looked at under a microscope. The second method is done by inserting a needle into the mass to gather cells. It's less accurate because it can miss some cells that could be cancerous.

You will need to keep the site clean and dry by changing the dressing daily. If an infection was found, your dog would be prescribed oral antibiotics.

Additionally, your vet may recommend an Elizabethan collar to prevent your dog from scratching or licking the incision. Depending on where the stitches are located, there are other collar options available that allow your dog to eat, drink, and rest more comfortably.

The cost will vary based on your dog's specific case and your vet's fees. A basic exam and needle biopsy can run up to $200, depending on the cost of living in your area. However, if your dog hasn't had blood work in a while, your vet may require a complete blood count to make sure the rest of the body is healthy, such as the liver, kidneys, pancreas, etc., and are not contributing factors.

There's a small chance that a histiocytoma can be transmitted from one dog to another, but humans and other animals are not at risk. There is no need to keep your dog in isolation while they have a histiocytoma, and you don't need to worry if your dog has been in contact with another dog that has a histiocytoma.

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