Many lumps in pets aren't problematic

Finding a lump on your pet's skin can be worrisome. How do you know if it is something bad? What should you do about it?

There is a long list of things that cause lumps. Some are innocuous; some are serious. Here are some of the more common types of benign lumps I see on pets, and the ways we identify and treat them. In the next column two weeks from today, I'll talk about some of the more common problematic lumps.

• Sebaceous cysts: The sebaceous glands are skin glands that excrete a waxy substance called sebum onto the surface of the skin. Sebum keeps the skin soft and coat shiny.

Sometimes the openings to a sebaceous gland get tucked under the surface of the skin and instead of secreting the sebum onto the surface of the skin, the glands secrete it into a pocket underneath the skin. As the waxy material accumulates with nowhere to go, it turns into a lump. These are known as sebaceous cysts and they are noncancerous.

Although the sebum can sometimes be squeezed from the pocket like popping a zit, the cyst will usually return unless the section of abnormal skin that is producing the pocket is surgically removed. Because most sebaceous cysts sit quietly and don't cause any health problems, the recommendation is usually to ignore them. If they are very large, become infected repeatedly (a common result from being poked frequently to drain the wax), or are otherwise making a nuisance, they can be removed fairly easily.

• Sebaceous adenomas: Those sebaceous glands are back at it, but this time the cells lining the inside of the gland have proliferated excessively and have created a little cauliflower-texture lump on the surface of the skin. I believe it is a legal requirement that all small white dogs older than 6 years must have at least one sebaceous adenoma. By age 12, many dogs will have bumper crops of them sprouting all over their bodies. These lumps are commonly called warts, but they are not contagious like the viral warts that people tend to get on their hands. Once again, surgical removal is the only way to get rid of these lumps, but because they do not cause systemic problems I recommend removal only if the lumps are causing irritation.

• Histiocytomas: These are pink raised lumps that appear on the surface of the skin over the course of a few weeks or a few months. They are the most common type of skin tumor we see in dogs younger than 5 years. Boxers and pit bulls are particularly prone to developing them, but any breed can be affected. When these lumps are left alone, the immune system eventually wakes up and realizes that they are not supposed to be there, and it sends in the cavalry to fizzle away the lump from the inside out in a process that takes from about two weeks to one month. The lump often becomes ulcerated and scabby. When the scab comes off, the lump is usually gone.

The problem with histiocytomas is that, to the naked eye, they are indistinguishable from serious types of skin cancer. Your veterinarian can uncover the identity of a lump only by using a needle to collect some of the cells and then looking at them under a microscope.

If there is any doubt, surgical removal is completely curative.

These are just a few of the common causes of benign skin lumps. Unless your veterinarian paid better attention during Psychic Powers 101 than I did, however, there is no way to make a determination about whether a lump is a problem or not without seeing the patient and doing some testing to determine what the lump is made from. At least you know that it isn't always bad news when you find a lump, so don't be afraid to find out the answer.

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Anne Pierce is a Colorado Springs veterinarian and co-owner of High Plains Veterinary Hospital. Contact her at petdocs@highplainsvet.com.