Nobody wants a lump or bump on his or her pet. Unfortunately, cancer can occur in nearly any type of animal, and the very possibility can be stressful for pet owners. Fortunately, some bumps are nothing to be concerned about, though telling the difference between the two can be challenging.
Both tumors and cancers occur when tissue grows abnormally. Benign tumors stay in one area, while malignant cancers spread by growing into surrounding body parts or catching a ride in blood vessels or lymph tracts.
Definitively telling the difference between a benign tumor and a malignant cancer involves taking samples of the area for examination. There is no general “cancer test” that can be done on an animal’s blood, though there are a few tests for very specific types of cancer.
One type of common and benign tumor is the lipoma. Lipomas are benign tumors of fat, and are very common in older dogs, especially retrievers. They typically are round, smooth and directly beneath the skin, so the hair on top is undisturbed. Lipomas, while benign, can be a problem if they grow too big, or are in the wrong location. Some lipomas can grow to the size of cantaloupe, and even smaller ones can interfere with leg movement or bodily functions if they are in the wrong place. If a lipoma is small and not causing problems, it may be considered a cosmetic problem rather than a health problem. Lipomas tend to grow in spurts, and may shrink with weight loss.
If an older dog has a lump, it is impossible to tell with 100 percent certainty whether it is a lipoma or a more serious growth without taking a small sample. Some serious cancers can mimic the “feel” of a lipoma and fool a person into ignoring them. Sometimes this sample can be taken with a needle in a procedure known as a fine needle aspirate, or FNA. Lipomas that become a problem, because of size or location, are usually easily surgically removed. Because they are solid tumors or fat, they cannot be drained with a needle.
Cysts are small pockets of fluid or solid material beneath the skin, and are not actually tumors. They tend to occur in older small dogs, but can occur at any age or in any breed. These pockets of fluid can become painful, or even potentially rupture as pressure builds. Some cysts grow to a certain size and then remain stable. Occasionally a cyst can be a sign of a more significant health problem; some tumors or cancers can also become cystic. Determining with absolute certainty that a lump is a cyst involves taking a sample of the fluid or solid matter within the capsule, often with a needle or through biopsy. Because the lining of the cysts is still present, simply draining the fluid or matter does not remove them; they typically grow back unless completely surgically removed.
Many lumps and bumps are not a big concern, though determining which are and which are not serious involves some work. Benign lumps can sometimes be ignored, as long as they are in the right location and not growing too fast. When in doubt, get your pet’s lump checked out!
Dr. Michael Rumore is the owner of Lake Seminole Animal Hospital.