Lumps, Bumps, Cysts & Growths on Dogs


By T. J. Dunn, Jr., DVM


There are very few surprises that will worry you more than discovering a new lump or bump on your dog. As your hand wanders over your canine pal, your fingers just may chance upon a lump that “was not there before." Your first though will probably be along the lines of “What is this?” followed quickly by “I hope it’s not serious.” Read on to learn how abnormal growths in dogs are diagnosed and treated and just how worried you should be.  


Common Lumps and Bumps on Dogs


The question most owners have when they find a new lump or bump on their dog is, "Is it a tumor?". The truth of the matter is that no one can tell you with 100 percent certainty what a mass is by simply looking at it. Your veterinarian may be able to make an educated guess with just an exam, but without taking a sample of cells and looking at them under the microscope or sending them to a pathologist for identification, a definitive diagnosis is simply not possible.


Sebaceous Cysts on Dogs


That said, not every lump or bump on your dog requires a full work-up. Some superficial bumps are just sebaceous cysts, which are plugged oil glands in the skin that are usually nothing to worry about. Skin cysts can be composed of dead cells or even sweat or clear fluid; these often rupture on their own, heal, and are never seen again. Others become chronically irritated or infected, and should be removed and then checked by a pathologist just to be sure of what they are. Some breeds, especially the Cocker Spaniel, are prone to developing sebaceous cysts. 


And yes, the sebaceous glands in the skin do occasionally develop into tumors called sebaceous adenomas. According to Dr. Richard Dubielzig of the University of Wisconsin, School of Veterinary Medicine, "Probably the most commonly biopsied lump from dog skin is a sebaceous adenoma. This does not mean it is the most commonly occurring growth, just that it is most commonly biopsied." Fortunately, this type of skin growth rarely presents trouble after being surgically removed. 


Lipomas on Dogs


The lipoma is another commonly encountered lump seen by veterinarians during a physical exam. These soft, rounded, non-painful masses that usually present just under the skin are generally benign. That is, they stay in one place, do not invade surrounding tissues, and do no metastasize to other areas of the body. They grow to a certain size and then just sit there and behave themselves.


How Do I Know Which Lumps are Dangerous


So how are you to know which of the lumps and bumps found on a dog are dangerous and which can be left alone? Truthfully, you are really only guessing without getting your veterinarian involved. Most veterinarians take a conservative approach to masses like lipomas and sebaceous cysts and only recommend removal if they are growing rapidly or causing problems for the dog.


However, every lump that is not removed should be closely observed. Sometimes, those that appear to be benign can turn out to be a more serious problem. Any mass that is growing rapidly or otherwise changing should be reevaluated.