When should a skin or subcutaneous mass be removed in an aging dog?
Everything you need to know about the assessment, diagnosis, and removal of skin masses in older dogs
Lumps on or under the skin are very common in aging dogs. Many are benign, such as lipomas or cysts. Others, such as mast cell tumors or soft tissue sarcomas, can be malignant, even when they appear small and harmless.
You can't determine what a lump is simply by touching it. The first step is usually a fine-needle aspiration: a quick and minimally invasive needle biopsy. A lump should be evaluated if it measures more than one centimeter, has been present for more than a month, grows, changes in appearance, bleeds, or bothers your pet.
Removal is recommended when the mass is malignant or suspicious, is growing, ulcerates, or is causing the dog discomfort. For a malignant tumor, the initial surgery often offers the best chance of complete removal.
Veterinary medicine is evolving rapidly. The information presented in this article is based on available recommendations and our team's experience at the time of publication. It is not a substitute for a veterinary evaluation tailored to your pet.
You pet your dog and feel a small bump under your fingers. It's soft, it doesn't seem to hurt him, and he continues to look at you with the same adoration.
The initial reaction is often to assume it's just a "fatty lump." And in many cases, that's indeed the case. The problem is that some malignant tumors are very good at disguising themselves. A soft, mobile mass could be a benign lipoma. It could also be a mast cell tumor, sometimes nicknamed "the great imitator."
The only way to know is to look at what's inside.
The most common masses in aging dogs
With age, several types of lumps can appear on or under the skin.
Among the masses, which are often benign:
a lipoma, an accumulation of fat cells, usually soft and mobile under the skin;
cysts, pockets filled with matter, sometimes associated with hair follicles;
sebaceous adenomas, small wart-like growths, common in older dogs;
papillomas, growths similar to warts;
Histiocytoma, more common in young dogs, often disappears on its own. Among the masses that can be malignant:
mast cell tumor, one of the most common malignant skin tumors in dogs;
soft tissue sarcomas, which can feel like a lipoma;
melanoma, especially when it affects the mouth or fingers;
Squamous cell carcinoma often occurs in areas with little pigmentation or that are exposed to the sun. There are also masses that are not tumors, such as an abscess, an inflammatory reaction, or a hematoma.
Why can't we judge a mass by touch?
The consistency, size or mobility of a mass does not allow us to know whether it is benign or malignant.
A mast cell tumor can be soft, firm, small, large, red, pale, hairy or bald. It can even change size from day to day.
A soft tissue sarcoma may appear well-defined, while it sends thin microscopic extensions into the surrounding tissues.
Your veterinarian may have a good intuition. But in oncology, intuition is no substitute for a diagnosis.
The rule to remember: see, measure, sample
Several veterinary organizations specializing in surgical oncology recommend a simple approach:
Any mass larger than approximately one centimeter, the size of a pea, that has been present for more than one month should be aspirated. A more rapid evaluation is recommended if the mass:
grows rapidly;
changes shape, color or consistency;
becomes red, swollen or ulcerated;
bleeds or oozes;
seems attached to the deep tissues;
cause of pain or discomfort;
is located on a finger, in the mouth or near an eye.
While waiting for the appointment, measure the mass with a ruler or tape measure, take a photo, and note its position. This information is valuable for monitoring its progress.
Fine-needle aspiration: a small procedure that guides everything
Cytological puncture involves inserting a thin needle into the mass to collect a few cells. These are then spread on a slide and examined under a microscope, either in the clinic or by a pathologist.
This procedure is usually quick and well-tolerated. Most dogs experience it as a vaccination, sometimes without even realizing it. Cytology often allows us to distinguish:
a mass of fat;
a cyst;
inflammation or infection;
a round cell tumor, such as a mast cell tumor;
a suspicious tumor that will require further examinations.
However, it has its limitations. Some tumors release few cells, and an inconclusive sample does not mean that the mass is benign.
When is a biopsy necessary?
When cytology fails to identify the mass, or when a malignant tumor is suspected, a biopsy may be recommended before surgery.
A biopsy involves taking a small piece of tissue, rather than just a few cells. It allows for a more precise diagnosis and, in some cases, the determination of the tumor grade.
This step may seem to delay treatment. However, it allows for the planning of the right surgery from the outset: the size of the margins to be removed, the reconstruction technique, and the need for further examinations.
After a mass is removed, it is usually sent for histopathological examination. The pathologist confirms the diagnosis and checks whether the edges of the removed tissue are free of tumor cells.
Withdrawal is generally recommended when:
the mass is malignant or potentially malignant;
the mass grows, even if it is benign;
It ulcerates, bleeds or becomes infected;
it hinders the dog's movements, walking or comfort;
Her position may make surgery more difficult if she continues to grow;
The diagnosis remains uncertain despite the tests.
A lipoma that grows under the armpit can eventually impair walking. A small lump on a leg, where the skin is sparse, is much easier to remove when it measures one centimeter than when it measures five.
Surgical decisions, management and recovery for skin masses
When can we monitor?
A mass can often be easily monitored when:
Cytology confirms that it is benign, like a typical lipoma;
it remains stable over time;
It doesn't bother the dog;
Its position is unlikely to complicate future surgery.
Monitoring doesn't mean forgetting. Measure the mass regularly, for example, monthly, and report any changes to your veterinarian. A chart of the masses, showing their location, size, and the date of the cytology, can be very helpful for a dog with multiple masses.
The first surgery is the most important
For a malignant tumor, the first surgery often offers the best chance of removing all tumor cells.
Some tumors, such as mast cell tumors and soft tissue sarcomas, extend beyond what can be seen or felt. To remove them completely, the surgeon must remove a margin of healthy tissue around the mass, as well as a layer of tissue deeper within it.
When a malignant tumor is removed without a plan, simply "shelled out," some cells may remain. A second, more extensive surgery, or other treatments such as radiotherapy, may then be necessary.
That's why it's best to know what you're removing before you remove it.
What if the tumor is malignant?
When a malignant tumor is confirmed or strongly suspected, further tests may be recommended before surgery.
This expansion assessment may include:
the puncture of nearby lymph nodes;
blood tests;
chest x-rays or an abdominal ultrasound;
sometimes advanced imaging, such as a CT scan.
These tests help determine if the tumor has spread and to choose the most appropriate treatment. Depending on the type of tumor, surgery may be combined with other treatments, in collaboration with an oncologist.
Can an older dog have surgery?
Yes. Age is not a disease, and it is not, in itself, a reason to forgo surgery. In older dogs, a pre-operative assessment allows for evaluation of their overall health and adaptation of the anesthetic protocol. Blood tests, and sometimes other examinations, may be recommended.
Removing a small mass early is often simpler, quicker, and less invasive than removing a large mass later, when the dog is even older. When anesthesia is scheduled for another reason, such as a dental cleaning, it can also be beneficial to take advantage of the opportunity to remove a small mass that has already been diagnosed.
Why hire a specialist team?
Several skin masses can be removed by your veterinarian.
However, a specialized surgical team can provide particular value in certain situations:
a malignant tumor that requires wide margins;
a large or infiltrating mass;
a mass located on a leg, the face, near a joint, or in an area where there is little skin;
skin reconstruction using flaps or other techniques;
a mass that recurs after initial surgery;
revision surgery after incomplete removal.
In these cases, the planning of the surgery and wound closure makes a big difference to the outcome, both for tumor control and for the animal's function and comfort.
And what about cats?
Skin masses are less common in cats than in dogs. However, when they do appear, they deserve special attention, as a significant proportion of them can be malignant.
In cats, a mass that appears at an injection site also warrants careful monitoring. Recommendations suggest evaluating any mass that persists for more than three months after an injection, measures more than two centimeters, or grows one month after the injection.
As with dogs, fine-needle aspiration or biopsy remains the first step.
What does recovery look like?
Recovery depends on the size of the mass, its position, and the closure technique used.
It generally includes:
pain medication;
wearing an Elizabethan collar or protective clothing;
monitoring the incision;
a restriction of activity for approximately two weeks;
sometimes a drain, removed a few days after surgery;
the points deduction, usually around 10 to 14 days.
Histopathology results are usually available in one to two weeks. They allow for confirmation of the diagnosis and determine whether further monitoring or treatment is necessary.
Can a mobile mass be removed during surgery?
Yes, in most cases.
Mass removal is one of the soft tissue surgeries that our team can perform at a suitably equipped partner veterinary facility, including some larger surgeries requiring reconstruction.
Your dog is operated on in an environment he already knows, and your veterinarian remains involved in the diagnosis, preparation and follow-up.
Certain cases, such as a tumor requiring advanced imaging to plan surgery or additional treatments, may be coordinated with a referral center or oncology department.
At Coupez, each case begins with the analysis of the results transmitted by your veterinarian: cytology, biopsy, photos, measurements and health assessment.
We assess the type of mass, its location, and the necessary margins. When a diagnosis is not yet established, we may recommend a biopsy or further tests before planning surgery.
When surgery is indicated and suitable for mobile care, our team will come to your location to perform it. Follow-up care is then provided in collaboration with your veterinarian. Your veterinarian identifies and diagnoses the mass. Our team plans and performs the removal correctly. Together, we aim to get it right the first time.
In conclusion
Not all masses are dangerous. But none should be judged by touch.
A quick fine-needle aspiration biopsy often helps determine whether it is simply a matter of monitoring, removing the mass, or planning a more extensive surgery.
The earlier a lump is assessed, the simpler the options remain. Your dog won't show you the lump. But your hands can find it.
