Submitted Date 08/05/2019

As your pet ages, you will find that she may accrue a variety of interesting (if not a bit gross) lumps and bumps. This may not worry you—you have plenty of your own! Or this may have you running to your vet with tears in your eyes and concerned about the big "C". The question is: when should you relax, and when should you panic over a lump?

There are so many different types of growths and masses that a pet can grow. Anything from a benign (non-cancerous) subcutaneous cyst to a malignant (cancerous) osteosarcoma (bone tumor) is possible. How are you as an owner supposed to know which is which? The truth is, even your trusted veterinarian cannot tell you for sure with just a glance. Of course, they can speculate based off of appearance, palpation, and any changes you've noted, but until you stick that mass under a microscope, there is no telling what resides within it.

Pet owners should be wary of any and all masses. You should notify the vet at your companion's next office visit should a lump or bump appear. It's important to keep track of changes such as growth over time, firmness of the mass, and "mobility" of the mass. Has it doubled in size since last month, or has it remained the same size for three years? Is it soft and squishy or is it as solid as a marble? Can you "pinch" it and move it around, or is it firmly attached to your pet? What about color? Did it start as a pinkish skin tone but has now morphed to a deep brown?

Just like in humans, animal masses can have some outward or clinical signs that are concerning or, at the very least, worth noting. Firmness is a noteworthy factor. Hard-to-the-touch masses can be a sign of malignancy. This is not true for every mass—such as when the mass is underneath muscle or if the mass is so large it renders the skin taut, it can feel very firm.

Another trait to monitor is mobility. When I say mobile, I mean that you can grab the mass and move it slightly side to side. If it's not budging, it's not mobile. Masses under the skin that are "moveable" are more likely to be benign. This is not always the case of course; for example growths on top of the skin are not going to move any, but that doesn't necessarily make them cancerous.

Rate of growth is also an important attribute to a mass. Malignant masses are more likely to grow at an exponential rate. Benign tumors tend to stay the same size or grow slowly over time, whereas a cancerous tumor might double in size within a couple of months. Again, both benign and malignant masses can grow at any rate—every type of tumor is different.

Other things to watch for when you discover a mass are things like how bothersome it is to your pet (or you!), color and color change, if it "ruptures" (masses, depending on the type, can sometimes open and ooze), and hair loss around the site. It's important to note whether a mass causes your animal pain, or if they chew or lick at the site. Extremely dark color can sometimes be a cause for concern. Benign cysts can rupture, but so can malignant tumors.

Now that your pet has a lump and you've recorded any growth or changes, what should you do? You may not be rushing to lob it off during a surgical procedure, but you should certainly have it tested. Again, your vet can never say for sure what a mass is upon appearance; they can only speculate based on its presentation. And they may certainly have a good guess (especially if it looks to be a skin tag, lipoma, or what we in the vet world affectionately call "old man warts"), but you should still consider testing it. Some masses can appear or "act" like other masses. The only way to be sure is to view the tumor's cells microscopically.

Testing can be as simple as poking the lump with a needle and collecting a sample of cells to be processed on a microscope slide. This is called a "fine needle aspirate cytology". The results of this are not always 100% accurate as the vet doesn't know what cells she just collected within the needle. It could just be blood and not an actual sample of the mass. Still, this is a much less invasive (and costly!) way to test your pet's lump. Sometimes veterinarians can even diagnose the mass right at the clinic (versus sending the sample out to a pathologist to view) if they have been trained to identify that type of mass.

A more accurate way to test a mass is to biopsy it. This can be done by surgically removing the entire mass, also known as an excisional biopsy, or by taking a small incisional biopsy, which means only a portion of the mass is removed. Either way, the pet must be anesthetized for these sorts of procedures, so in most cases, it makes sense to take the entire mass, and even margins around the mass. Sometimes, due to size, placement, or other factors, an incisional biopsy must be taken instead. Submitting tissue for a histopathology report will receive more accurate results than a fine needle aspirate cytology, at a more expensive procedure. There is a lot involved in removing a mass!

Now that you've received results of your furry friend's mass, what are you supposed to do? That all depends on the diagnosis. Some masses should be surgically removed; others can simply be monitored. Cancerous growths may need to receive chemotherapy or radiation. One thing is for certain: if it is bothering your pet, it needs to go. Even benign masses should be considered for surgical removal if the pet is bothered by them (i.e. licking, scratching, chewing, expressing pain from the mass, or if mechanical movement is affected by the mass).

It's important to listen to your vet's advice on the matter. You should always monitor a lump on your pet for growth and change. These can be indicators that the mass may now need to be removed. Overall, the key to masses is vigilance. Stay on top of your pet's lumps and bumps, so that as soon as one appears, you can notify your vet and take any necessary action.

Please remember that this blog is NOT meant to replace your veterinarian. You should always seek your veterinarian for medical advice on your pet. Tumors are too diverse to use this information to attempt to diagnose a mass. If your pet develops a mass, talk to your vet.


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