Mar Vista Animal Medical Center

3850 Grand View Blvd.
Los Angeles, CA 90066




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GLAND TUMORS(original graphic by

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We receive a fair amount of email from our Papillomavirus page from people with older dogs with numerous "warts" wondering if their dog's warts will go away as viral warts usually do. The problem is that in older dogs, what looks like a viral wart is probably a sebaceous gland tumor, while there is a 98% chance it is benign, it will not be going away any time soon.

It is not uncommon for an elderly dog to develop scores of "warts" which are not warts at all but are sebaceous growths. They are generally of cosmetic concern only but removal is recommended under the following circumstances:

  • when the growth has been bleeding.
  • when the growth is itchy or is in a location where it is bothering the pet.
  • when the growth is in a location where it interferes with normal grooming of the pet (i.e. the growth gets caught in the grooming clippers etc.).
  • when there is a question as to whether the growth actually IS a sebaceous tumor and biopsy is needed to settle the question.

These growths are typically small (pea size or smaller) and are thus generally amenable to removal with local anesthetic. This is helpful since often patients are older and not good anesthesia candidates. It is usually not practical to remove all the sebaceous growths but the most troublesome can be selected for removal.

Viral warts occur primarily on the face of young adult and adolescent dogs. Sebaceous gland tumors occur on any location, often in large numbers, and usually in older dogs (and occasionally in older cats).


There are several types of sebaceous gland tumors:

Nodular Sebaceous Hyperplasia

About 50% of sebaceous growths are technically not tumorous and fit into the sebaceous hyperplasia group. It is thought that this group ultimately progresses to the actual benign tumors described below. These lesions are round, cauliflower-like, and sometimes secrete material that forms a crust. Occasionally they even bleed. They are particularly common in Cocker spaniels, Beagles, Miniature Schnauzers, Poodles, and Dachshunds. This growth is technically not a tumor but is actually an area of excessive sebaceous cell division.

Sebaceous Epithelioma

Another 37% of sebaceous growths fit into this category. These look just the same as sebaceous hyperplasias to the naked eye but tend to occur in larger breeds and usually on the eyelids or head. They often pigment into a black color. They are actual benign tumors and not just areas of excessive sebaceous cell division.

Sebaceous Adenoma

These lesions also look the same as the others to the naked eye. These are also actual benign tumors that probably arose from areas of hyperplasia.

Sebaceous Carcinoma

About 2% of sebaceous tumors are malignant and may be locally invasive but even malignant sebaceous tumors rarely spread. They have a greater tendency towards ulceration than do the benign growths. Cocker spaniels seem to be predisposed.


Again, in most cases removal of sebaceous gland tumors is straight forward and can frequently be done with a simple local anesthetic. In the event that further treatment is needed, your veterinarian will inform you of options.

Date last updated: 2/5/2019
Page last reviewed: 3/18/2021