There are several types of skin tumors that develop from the skin and adnexa (the parts adjoining the skin). The most common tumor is the Lipoma, commonly referred to as a “fatty tumors” and the second most common is a tumor arising from the sebaceous glands called sebaceous adenomas.
The sebaceous glands produce an oily substance called sebum, which lubricates the skin. The ducts of the sebaceous glands empty into hair follicles. A different problem that can occur in dogs that arises also from the sebaceous gland is a Sebaceous Cyst, but is less common in dogs.
Overview of Sebaceous Adenoma in Dogs
The development of sebaceous cysts is thought to develop from an obstruction of the follicles, leading to abnormal accumulations of sebum.
Sebaceous adenomas are benign tumors that originate from the landular or ductal tissue. In dogs, they are common on the head, neck, back, eyelids and limbs. They are generally hairless protrusions firmly attached to the skin. They can have the appearance of cauliflower.
Sebaceous adenomas develop more often in dogs as they get older and are most common in dogs over the age of 7 to 8 years. Dogs that are prone to sebaceous adenomas tend to get more sebaceous adenomas as they age.
What to Watch For
Sebaceous adenoma can turn into sebaceous adenocarcinoma, which is a malignant tumor. Please monitor your pet for any changes in the sebaceous adenoma that could suggest a malignancy including rapid growth, changes in color, or ulcerations.
Diagnosis of Sebaceous Adenoma in Dogs
The diagnosis of a sebaceous adenoma in your dog will largely be based on the history and examination of the mass. Veterinarians can often diagnose sebaceous adenomas be physically looking at it.
Dog owners often mistake a sebaceous adenoma with an Acrochordon or Fibroepithelial Polyp in Dogs (commonly referred to as a dog skin tag) or with Canine Viral Papillomas (commonly referred to as dog warts). This article may be helpful in the section that tells you how to tell a skin tag from a wart.
Your veterinarian will ask questions about your dog's mass that may include:
- How long has the mass been there?
- Is there only one mass or are there others?
- Has it gotten larger or smaller or changes in appearance?
- Does the mass appear to be attached to the underlying skin?
- How fast is it is growing?
- Have there been any recent injuries or injections?
- Are there any changes in your pet's behavior, such as eating less, weight loss, vomiting, diarrhea or lethargy?
- Are there any other lumps, tumors, masses, or growths?
A complete physical exam will be done and your veterinarian will pay particular attention to the appearance of the mass, whether it is hot or painful, whether it is within the skin or under the skin, if it is attached to underlying tissues, if it is ulcerated, and where it is located on the body.
Additional tests may include:
- Fine needle aspiration. A diagnosis can often be made by placing a small needle within the cyst and suctioning some cells out of it with a syringe. Microscopic evaluation of the cells will often be suggestive of a sebaceous adenoma.
- An aspirate of the mass with a small needle may be done to collect cells for staining and examination under a microscope (cytology). This test usually requires no anesthesia and often leads to a diagnosis.
- If the mass is ulcerated or draining fluid, a microscope slide may be touched to the fluid to make an impression for microscopic examination. This is referred to as an “impression cytology”.
- A biopsy may be taken to send to a veterinary pathologist for examination. The biopsy may involve removing the entire mass or removing a piece of the mass.
- A piece of tissue may be submitted for culture if infectious agents such as bacteria or fungi are suspected.
Treatment of a Sebaceous Adenoma in Dogs
If the growth is diagnosed as a sebaceous adenoma, no treatment is required. However, some sebaceous adenomas break open, bleed, become infected or are irritated by leashes, collars, halters and/or grooming procedures. Some sebaceous adenomas are close to the mouth and become damaged when eating. Another common location is on the eyelid that can cause the mass to rub on the eye potentially causing corneal ulcerations. In these cases, surgical removal of the sebaceous adenoma is recommended.
Sebaceous adenoma can be removed surgically by removing the mass with a wedge of underlying skin to ensure the entire mass is removed. Surgery can be performed under general anesthesia however some sebaceous adenomas can be removed using local anesthesia such as lidocaine.
Using local anesthesia will depend on the location of the mass, size of the mass, and your dog's personality. For example, a small mass on the top of the head or neck in a calm dog may do well with a local anesthetic to remove the sebaceous adenoma. In these cases, lidocaine is injected around and under the mass until the skin is numb and a surgical blade is used to excise the mass.
When using general anesthesia, surgery for a sebaceous adenoma is often combined with other elective procedures such as a dental cleaning.
Sutures are generally placed in the skin that needs to be removed in 10 to 14 days after surgery.
Evaluate the sebaceous adenoma for changes in color, ulceration, increase in size, redness, swelling and/or pain. If any changes occur, please see your veterinarian. If the growth has been removed or biopsied, keep your dog confined to allow for healing. Do not allow your dog to scratch or lick at the surgical site.
If your dog has surgery, please observe the incision site closely for drainage, swelling, redness, heat or pain that suggestion infection and notify your veterinarian if you see abnormalities. Follow-up with your veterinarian for suture removal if required.
Prevention of Sebaceous Adenomas in Dogs
There is no known way to prevent sebaceous adenomas in dogs. There have been reports that sun exposure may increase the occurrence of sebaceous adenomas in light-coated and white dogs. Minimize sun exposure. Monitor your dog closely for additional growths or abnormalities and consult with your veterinarian.