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Updated: 11/13/2013 08:00:03AM

What about the lump on my dog (or cat)?

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Lumps in animals should be checked out and the general rule is that if it growing it could be cancerous. This lesion is a mast cell.

Thomas B. Schotman

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Many of our dog and cat patients present with lumps or bumps on the skin, mostly benign and not a serious health risk to the animal. Cutaneous growths can be serious. If a lump is growing, there is a significant likelihood that it is cancer, and it is best diagnosed and removed while it is small. The larger a skin tumor the more likely it has spread or metastasized.

Many dogs will develop skin tags, sebaceous cysts, or moles which are benign growths called histiocytomas. These are not a health risk to the animal but may be a nuisance to the owner or the groomer. Cysts may rupture and drain. Larger tags or moles may bleed or scab over if disturbed. Usually surgical removal is the best resolution of these skin issues, even though they are not a bigger risk to the dog ( or cat).

There are a large numbers of more serious growths on dog and cat skin that are not benign and could create a health risk in time. Many cases I have seen have had a lump that was there for a long time (pre-cancer?) that suddenly began tO grow. One dog had a mass the size of golf ball that was not there (per the owner!) on week prior. In both cases I diagnosed cancer by performing a fine needle aspirate and examining the cells under the microscope. Both cases were resolved by surgical removal.

It is imperative that any skin lesions be identified to allow removal before spread of a cancer can occur. A biopsy of a mass for specific diagnosis by a pathologist is best, although I prefer to do excisional biopsy by removing a skin mass completely and then sending the samples for identification. One surgery instead of two.

Mastocytomas or mast cell cancers are commonly found and easily diagnosed and usually resolved by early excision. These tumors can be grade 1 , 2 or 3, and like most cancers, the earlier diagnosis and removal the better the prognosis. There are many other skin cancers of the dog and cat, including some that are also found in humans, like Squamous Cell Carcinoma and Melanoma. Do not let a growth on your pet’s skin get large before it is diagnosed and/or removed.

I have always had a rule that no dog or cat should get old intact, meaning that ALL animals should be spayed or neutered before they get too old. In this article I refer to mammary cancer.

In the female dog that is not fixed it is very common to find some mammary cancer or pre-cancer by age 8-10. While data indicates that early ovariohysterectomy (before the first heat) will prevent this cancer, it is well recognized that dogs over 3 to 4 years old have a higher predisposition for mammary cancer as they get older. Early recognition in the dogs and surgical removal before metastasis is curative. In cats this cancer is much more likely to spread earlier in the staging. It is appropriate to examine for lumps and bumps.

The best advice is to be concerned about any lump or bump on your dog or cat. Have your veterinarian diagnose and deal with it as is appropriate … before it it too big or too late to resolve.

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