Foul-Smelling Tumors in Dogs

Cuteness may earn compensation through affiliate links in this story.
Foul-Smelling Tumors in Dogs
Image Credit: Chalabala/iStock/GettyImages

Suddenly finding a lump or tumor on your dog that was not there before can be alarming. For most of us, thoughts immediately turn to "The Big C" — cancer. But most of the time lumps on dogs turn out to be benign fatty tumors called lipomas.


Video of the Day

Lipomas are dogs' most common noncancerous soft-tissue growth. Lipomas do not stink. They don't even have to be removed as long as they're not in a spot, like your dog's face, which could interfere with his normal functioning. Your vet can usually tell if a lump is a lipoma just by feeling it.

Cysts and abscesses are different. While not cancerous, in most cases they should be treated by a vet. If you find a foul-smelling oozing growth on a dog, it's most likely a sebaceous cyst or an abscess.

Is it a sebaceous cyst?

Sebaceous cysts are not uncommon in dogs. A sebaceous cyst is a blocked oil gland. It usually looks like a big pimple. A sebaceous cyst may hang out just under your dog's skin for a long time and not cause any trouble. However, it can become infected.


You'll know if the cyst has become infected because it usually grows in size quickly, turns red, and may be hot to the touch. When a cyst is infected it usually smells bad. Really dirty laundry comes to mind.

Sometimes this type of dog tumor ruptures on its own. If it doesn't your vet will cut an opening in it to release the gunk inside. When a sebaceous cyst is opened, greyish white pasty stuff oozes out. And yes, it smells. It smells very, very bad. Let's just say it will make you long for the odor of really dirty laundry.

Don't be discouraged if the cyst returns. They have a way of doing that. Just keep an eye on it. If it interferes with your dog's normal functioning or looks infected, back to the vet, you must go.


Or is it an abscess?

Abscesses are another variety of smelly tumor that dogs get. Abscesses contain pus. They are by definition infections. Abscesses are most often caused by bacteria that have gotten into an open wound. The wound doesn't have to be big. It could be as small as a bug bite.

A healthy dog's immune system will usually do battle with a small infection and win. But sometimes it loses. This is particularly true of larger wounds.

An abscess usually feels warm when you touch it. Abscesses can be very painful. They should be treated by your vet as soon as you find one. In most cases, because of the pain, your dog will have to be anesthetized before your vet can treat the abscess.


My dog’s mouth tumor smells

Oral tumors can be especially challenging. Because of their location, they're often not detected early. Some common signs that your dog may have an oral tumor are bleeding, swallowing food whole instead of chewing it, drooling a lot, and bad breath.

Other signs include food dropping out of her mouth while she eats, not playing with her toys, and pulling away when you try to touch her face or mouth.

If your dog's mouth tumor smells it probably means there's an abscess in there, which means she's in pain and has an infection. Dogs can get a periodontal disease from neglected teeth just like us. Tooth and gum disease is a major cause of oral abscesses.


A good cleaning by your vet is in order. He will remove plaque from your dog's teeth and treat any abscesses. He may also have to extract especially bad teeth to rid the mouth of the infection completely.

When tumors might be cancer

Although most tumors we find on our dogs are not cancerous, if your dog shows other signs, cancer should be ruled out. Early warning signs of cancer include loss of appetite, low energy, rapid unexplained weight gain or loss, and unusual (particularly black) poop. A lump plus any of these signs does not necessarily mean cancer, but they certainly warrant a trip to your vet.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.