The definition of a cyst is a fluid filled sack. The most common type of cyst is the sebaceous gland cyst found in the skin of dogs and cats. Cysts can occur anywhere on the body and at any age. Cysts are often dynamic, meaning that they can both increase as well as decrease in size over time. Certain breeds are genetically more prone to developing cysts. Cysts are not considered dangerous or threatening to the health of the pet unless they should rupture externally and subsequently become infected. If this was to occur then it is best to remove them surgically.
The sebaceous gland is the wax or oil-producing gland of the skin with a duct that empties into the hair follicle. A cyst occurs when the sebum becomes trapped inside the sebaceous gland. As the gland produces the fluid the cyst begins to “grow” or increase in size. When enough fluid has been produced to fill the sack the pressure inside the sack builds up to the point that stops the cells from producing additional fluid. As the fluid is reabsorbed or the wall stretches the pressure drops inside the sack allowing the cells to begin producing fluid again. At some point there is a standoff and the size of the cyst stabilizes for a period of time.
When you look at a cyst from the side you may see the cyst bulging above the level of the surrounding skin. The cyst wall may vary in thickness from very thin to very thick in nature. When palpating a cyst you should feel a balloon like structure that extends partly below the basement layer of the skin but mostly within the skin. The clinical diagnosis of a cyst can then be confirmed by inserting a needle into the sack and withdrawing fluid from the contents.
Treatment may not be necessary as long as the cyst does not become infected or interfere with the comfort or the function of the pet. Occasionally a cyst will “disappear” due to an internal rupturing of the sack contents thus allowing the fluid to be reabsorbed by the body. If it should rupture externally then surgical removal is almost always recommended and using the laser unit is the best means to accomplish this . Most veterinarians will not have good success from simply draining or squeezing the cyst because the secretory cells have not been removed and thus the cyst will return.
Sometimes it is hard to tell the difference between a cyst and a tumor or other growth, as they can look alike. It is best to let your veterinarian examine your pet to determine the nature of the various lumps and then follow his/her advice accordingly.