Dr. Kim A. Nicholas, a veterinarian at Cedar River Animal Hospital in Renton, answers this week's questions.

Question: Should owners have the bumps and/or lumps on their dogs' skin removed?

Answer: Not always. Many bumps and lumps are not cancerous. If a noncancerous growth is not bothering your pet, it may not need to be removed. Your veterinarian will consider the age of the pet, the location of the lump, the appearance, the texture, color and rate of growth of the mass to determine the most likely diagnosis.

For example, young pets are statistically less likely to develop cancer than an older pet. Some breeds are genetically more vulnerable to certain cancers. Boxers, for example, often develop cancerous mast cell tumors. Others, such as the basset hound, commonly develop noncancerous skin cysts.Your veterinarian may recommend a biopsy to determine if it is cancerous or benign.

Question: Is there any easy way to tell if the bumps are dangerous or ought to be looked at by a vet? Color, size, location?

Answer: There is no easy way to tell if a lump or bump is dangerous. The only way to know for sure is to remove it or at least get a piece of the mass and have it microscopically evaluated by a veterinary pathologist. In some cases, the veterinarian will place a small-gauge needle into the mass and collect cells for evaluation.

Because the sample of cells in this technique is small, sometimes the results do not give a definitive diagnosis. For a more complete determination, a local or general anesthesia is needed to get a larger section of the mass for the pathologist to review.

Warning signs to watch for in a potentially cancerous mass include a lump that is rapidly growing, changing texture, changing color or bothering the pet. Those should be checked by a veterinarian.

Dogs can develop benign cysts like this one.
Photo by Roxann Watson

Question: Can they be burned off or must they be cut out?

Answer: There are several ways a skin lump can be removed. Scalpel, freezing and laser surgery are the most common ways to remove a skin mass.
In some cases, a small and superficial skin mass can be removed with just a local anesthesia. In most cases, the mass may be large and deep enough within the skin and surrounding tissues that the proper removal requires general anesthesia.

Question: Are hard lumps more dangerous than soft-tissue lumps?

Answer: Not necessarily. Lumps and growths are an abnormal accumulation of cells. Every cell type behaves differently. Noncancerous fat deposits, called lipomas, can be soft and easily moveable under the skin. However, the same lipoma between muscle layers can be hard, non-movable and painful. A skin cyst can feel hard and painful but not be cancerous.

Being hard or soft does not matter as much as the activity and behavior of the cells within the mass. Some tumor cell types have a more aggressive and destructive behavior than others.

Question: Why do dogs seem to produce more lumps as they get older?

Answer: We don't really know. Some theorize that the pet's immune system weakens with age, allowing lumps to grow. Sometimes the masses are caused by a virus that the pet becomes exposed to over time. But mostly, we truly do not know.

Dr. Kim Nicholas

Nicholas grew up in the Seattle area and started working for a veterinarian when he was 14. He completed his undergraduate and veterinary degrees at WSU, where he also received a master's in the department of veterinary virology and immunology. He has owned and operated Cedar River Animal Hospital in Renton since 1986.

Read our previous Q&As:

Veterinary QA: What dogs can safely chew
Veterinary QA: Why does it cost so much to clean a dog's teeth?
Veterinary QA follow-up: More on cleaning a dog's teeth
Veterinary QA: When to spay or neuter

Do you have a question about pet health? Ask now! We'll pose some of your questions to a local vet in an upcoming post.