Pet Articles

Dog and Cat Skin Lumps

Evaluating and treating dog and cat skin lumps – Dr. M. Slome DVM

Skin lumps are one of the most common conditions that Veterinarians are faced with on a day to day basis.

A general approach to lumps is to determine whether there is a malignancy or if they are benign – is it ‘black or white’. The very big problem that health professionals are faced with is that most of them are ‘grey’.

It is for this reason that often it is recommended to have these lumps evaluated and rather be over cautious than ignore the problem until it really does become a problem. Evaluation of the skin lumps may firstly entail doing what is known as a Fine Needle Aspirate. This is a technique which involves sticking in a large type needle through the centre of the lump after it has been surgically prepared (shaved and disinfected) and using a larger syringe to apply negative pressure (sucking up hard with the syringe) to try and obtain at least enough material from the lump to place on a slide, smear the content in a thin layer, stain it and have it evaluated under microscope. The unfortunate problem with this technique is that it is only 50% accurate since the slide may be non diagnostic if the tissue is too dense and cannot pick up an adequate sample from the lump.

The next option is to take a biopsy of the lump which means removing a piece of tissue from the lump surgically and send it off to the pathologist for evaluation. Once the result is obtained, it may be more scientifically determined which course of medical intervention would be best.

The next option is to surgically remove the whole lump and send it in for evaluation to determine the prognosis of full recovery. Often this latter option is the most preferred as it will remove the whole lump and pathology will give a definite answer. To do a biopsy will usually require a general anaesthetic, and if you are going to that extent, you may as well remove the whole thing then rather than have to operate a second time. There are exceptions though when it is actually advised against to remove the lump before doing a biopsy first to determine what you are dealing with and this is something that only experienced professionals are sometimes able to determine.

My approach to evaluate lumps involves a careful history and clinical examination of the lumps. It is essential to find out:

  1. Does the lump bother the pet. Is it painful, itchy or tender. Is there an appearance that it has been chewed at or licked at incessantly and caused the lump to be traumatized and bleeding and raw. If there is no history of the lump being traumatized, then one has to consider that there may ulceration of the lump which generally means a less favourable prognosis. It is for this reason that it is important to provide as accurate information as possible to you Veterinarian. My approach is that if it bothers the pet, have it sorted out – either surgically removed or aggressively managed medically and if it does not respond within a short space of time, don’t wait – remove it. I would rather removed a small irritating lump that the pet is bothered by than a large one that is not bothering the pet and would appear to be benign based on experience.
  2. How long has the lump been there. Older lumps that don’t look good now are less favourable. Newer lumps may be from self trauma again – may be itchy skin from allergies, cuts, scrapes, insect bites, injection sites from previous vaccines. Newer lumps may be treatable with non surgical options and seeing as they arose recently and quickly, you generally have the option of trying medication of just observation for a determined period of time, before deciding to take further action. My general approach to a lump that has arisen suddenly: if it turns out to be malignant and is so aggressive that you do not at least have 1-2 weeks to try conservative treatment, then I don’t believe there is a good chance of recovery however soon it was surgically removed once diagnosed.
  3. How old the pet is. Middle to older pets have a greater chance of having malignancies.
  4. Location of the lump – whether over the mammary tissue, lymph glands and whether it is more deeply located under the skin in the muscle tissues, these need to be addressed more urgently.
  5. The owners play a large role in determining the next step. Often a lump may be tiny and look like a benign pimple but the owner is very concerned. The Veterinarian has to recognize this and while he/she may feel it is likely something that can be monitored for a period of time, it may not be worth the stress of the owner to endure and rather pick up on the feeling of the owner. To have a benign lump removed because the owner is worried is not harmful to the pet and as long as the owner perceives the cost of this to be acceptable, it is prudent to rather remove the lump and be safe. On the flip side, there are often large, ulcerating lumps that are not healing, been there for months and seem obviously more serious, and the Veterinarian will strongly advise to have the lump evaluated as soon as possible. The owner may elect not to pursue this farther but understand the future consequences to the decision. Often the decision would be financially based. It is quite sad and funny at the same time though, when finances are not an issue and while recommending more immediate action, owners may still opt to not do anything. On a 15 year old pet it is understandable, on a 6 year old pet, I often wonder why the owner has brought the pet in if they do not follow sound advice. I guess what I am trying to say here, is that a client/Veterinarian is most important to make a sound decision. You need to trust your professional health provider.

There are no easy answers to deciding when a lump should be investigated or removed. The above points should help you decide when it is time to act though. Be prepared in some cases to have to spend money to find out, but don’t resent the Veterinarian if the result comes up with something benign. If you trust your Veterinarian, you will know he/she has merely acted out of concern and in your pet’s, a valued family member’s, best interest.

There are so many different types and causes of lumps to mention them but here are a few that are more commonly encountered in practice.


Sebaceous cysts, Hair follicle cysts, Folliculitis (looks like measle bumps with fur falling out over the bumps), common wart, Sebaceous hyperkeratosis (look like raised pink pimples of different sizes and have creases in them that looks like cookie dough), Epulis (nodular growths in the oral cavity)


Mast Cell tumours, Basal cell tumours, skin or lymph gland lymphomas, melanomas

I hope this gives some general insight whether to remove or observe skin lumps.

Martin Slome DVM

Centre Street Animal Hospital
7700 Bathurst Street
Units 40-42
Thornhill, On.
L4J 7Y3
Tel: (905) 771-9855

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