Should I be alarmed by dog or cat cysts?
By: Ernest E. Ward, Jr., DVM
What cysts occur in dogs and cats?
Cysts, or tumors, are hollow spaces within tissues and contain either a liquid or a solidified material; the contents may be a natural bodily secretion or an abnormal breakdown product. Some cysts develop within a cancerous lump, but we’re only discussing non-cancerous cysts here. Non-cancerous cysts include:
- True cysts, which form in glands as a result of blocked ducts. In animals, a common type of true cyst is the one that forms in sweat glands. Complete removal or destruction of the true cyst lining may be necessary to prevent recurrence.
- Follicular cysts, which are dilated hair follicles containing fluid or dark-colored cheesy material. They’re also known as epidermoid cysts and are prone to secondary infections. Dilated pores and blackheads are related to follicular cysts but have wide openings on the surface.
- Sebaceous cysts, which are filled with sebum (skin oil) and develop in and around sebaceous glands associated with hair follicles. These common cysts are also prone to secondary infections.
- Dermoid cysts, which are complex congenital cysts, which means they’re present at birth.
- False cysts,which are fluid-filled structures formed by hemorrhage or trauma that leads to tissue death; the fluid within them develops when the dead tissue liquefies.
What causes cysts in dogs and cats?
There are numerous causes for cysts to develop in pets:
- Blockage of the opening of the hair follicle pore
- Sun damage or follicular inactivity (e.g. Mexican hairless and Chinese crested dogs)
- Treatment with certain drugs including steroids
- A lack of oily secretions in diseases such as sebaceous adenitis
- Inherited predispositions due to breed, such as Schnauzers and Yorkshire terriers
- 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, which occur most frequently in the Rhodesian Ridgeback dog, develop because the skin fails to close properly so the outer epidermal tissue becomes trapped within the deeper tissue
- Hemorrhage, trauma or even an injection reaction
Are these common tumors?
- Sweat gland cysts are common in dogs and cats, particularly on the eyelids.
- Follicular and sebaceous cysts are common in dogs. Cats get them less frequently except for “feline acne” on the chin and “stud tail” on the upper tail.
- Dermoid cysts are rare.
- False cysts due to trauma are fairly common in dogs.
What do these cysts look like… and what do they do?
- Follicular and dermoid cysts are unsightly and may fill with an unpleasant, soft cheesy material (keratin). This material may become secondarily infected with bacteria or yeast, producing a foul smell.
- Sweat gland cysts are nodules that are are usually slightly translucent and blue or dark in color; often the surrounding hair will be lost. You may see several of them, 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.
- It’s important to note that cysts in dogs and cats can’t harm people.
How are these pet cysts diagnosed?
- For an accurate diagnosis, your vet will recommend a tissue examination under a microscope (called histopathy).
- 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 by a veterinary pathologist.
- If the sample is the complete lump, the pathologist can assess whether the entire mass was successfully removed.
- Histopathology can also help the pathologist 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, laser treatment is useful for sweat gland cysts.
- Topical treatment, such as a cream, can be used with multiple small follicular cysts.
- Other treatments may be needed to address the primary causes, and sometime if the underlying cause is removed, some cysts will decrease in size or disappear on their own. Cysts due to trauma can resolve in time.
How can I help my pet?
- Prevent your pet from rubbing, scratching, licking or biting the cysts so you can help reduce inflammation, infection and bleeding.
- If the cyst becomes ulcerated, you’ll need to keep it clean and your pet may require a protective bandage over the area until it heals.
- After surgery, you’ll need to keep the incision site clean and dry, and your pet shouldn’t be allowed to interfere with the site.
- Call your vet immediately if you see significant swelling, bleeding, or loss of sutures after surgery. If you require additional advice on post-surgical care, please ask.
How will I know if the cyst has been permanently cured?
In many cases, excision leads to a complete cure.
If your pet develops recurrent or multiple cysts, it’s necessary to determine the underlying cause through diagnostic investigation. If cysts are genetic (e.g. Mexican hairless dogs), there will always be a tendency to develop further cysts.
The great news is -your vet can treat cysts right away to help your pet.
Contact your vet if you detect cysts on your dog or cat.