What is a cyst?
Cysts are hollow spaces within tissues that contain either a liquid or a solidified material. Occasionally cysts will develop within a cancerous lump. They are a benign form of cancer.
What type of cysts are there?
True cysts have a membrane that line its inner surface and produces secretions. Often, they are a result of blocked ducts. Complete removal or destruction of the lining may be necessary to prevent recurrence of a true cyst. In animals this most commonly forms in sweat glands.
Follicular cysts (epidermoid cysts) are dilated hair follicles containing fluid or dark-colored cheesy material. They are predisposed to developing a secondary infection. Dilated pores and comedones (blackheads) are related to follicular cysts but have wide openings on the surface.
Sebaceous cysts fill with sebum and develop in/around sebaceous glands that are associated with hair follicles. These are also prone to secondary infections.
Dermoid cysts are complex congenital cysts.
False cysts are fluid filled structures that do not contain a secretory lining. False cysts may be formed by hemorrhage or trauma that leads to tissue death; the fluid within them develops when the dead tissue liquefies.
What do we know about the cause?
Comedones and follicular cysts are secondary problems that occur because of local injury, blockage of the opening of the pore or follicle, mechanical or “pressure point” damage, sun radiation damage, or follicular inactivity (e.g. Mexican hairless and Chinese crested dogs). Some follow treatment with drugs such as “steroids”. Others may form due to a lack of oily secretions. There is an inherited predispositions as in breeds such as Schnauzers and Yorkshire terriers
Comedones on the sternum and other pressure points are not uncommon in dogs with thin coats and little body fat. Multiple and recurrent follicular cysts may develop on the heads of young dogs. Boxers have a predilection for these cysts.
Dermoid cysts along the midline develop during embryonic growth and occur because the epidermis fails to close properly; the result of this developmental abnormality is that isolated islands of the outer epidermal tissue become trapped within the deeper tissue. Dermoid cysts occur most frequently in the Rhodesian Ridgeback dog.
False cysts due to hemorrhage or trauma are common on the flank. A few are idiosyncratic reactions to injections.
Are these common?
Follicular and sebaceous cysts are common in dogs but unusual in cats, with the exception of “feline acne” on the chin and “stud tail” on the upper tail. Dermoid cysts are rare. Cysts due to trauma are moderately common in dogs. Sweat gland cysts are common in dogs and cats, particularly on the eyelids.
How will these affect my pet?
Follicular and dermoid cysts are unsightly and may fill with an unpleasant, soft cheesy material. This material may become secondarily infected with bacteria or yeast, producing a foul smell.
Sweat gland cysts are nodules or vesicles, approximately 1/8 of an inch in diameter. They are usually slightly translucent and blue or dark in color; often the surrounding hair will be lost. They may be multiple, particularly around the eyes and in the ears.
Cysts filled with blood often look dark. With the naked eye they may be difficult to distinguish from cancers.
How are these diagnosed?
Accurate diagnosis relies upon microscopic examination of tissue, not cells. Cytology is not diagnostic for cysts. Histopathology is necessary for the accurate diagnosis of these benign tumors. Your veterinarian will either take a biopsy of the tissue or remove the entire lump and submit the tissue to a specialized laboratory for evaluation. Histopathology may also help determine the cause of the cyst, predict the behavior of the tumor (prognosis) and rule out other forms of cancer.
What types of treatment are available?
The most common treatment for cysts is surgical removal. If available, cryotherapy is useful for sweat gland cysts. Medical treatment of multiple small follicular cysts can be used.
Can this problem disappear without treatment?
If the underlying cause is removed, some cysts will decrease in size or disappear. Cysts due to trauma can resolve in time.
How can I help my pet?
Preventing your pet from rubbing, scratching, licking or biting cysts will reduce inflammation, infection and bleeding. If the cyst becomes ulcerated, it will need to be kept clean and your pet may require a protective bandage over the area until it heals.
After surgery, the incision site needs to be kept clean and dry, and your pet should not be allowed to interfere with the site. Report any significant swelling, bleeding, or loss of sutures to your veterinarian. If you require additional advice on post-surgical care, please ask.
Are there any risks to my family or other pets?
No, these are not infectious and are not transmitted from pet to pet or from pets to people.
If you believe your pet has a cyst and would like it to be examined please contact Meadowlands Veterinary Hospital at 201-646-2008 or visit us at www.meadowlandsvethospital.com