Signs of Oral Cancer in Dogs: Mouth and Gum Lumps to Watch For

Signs of Oral Cancer in Dogs

• A visible mass on the gums, palate, tongue or inside the lips. It may be dark, pink or red, smooth or cauliflower-like, and may ulcerate.^8,2,5
• Bad breath that is unusually strong or new^2,8
• Drooling, sometimes with blood^7,5
• Bleeding from the mouth^7,3
• Loose or lost teeth^8,5
• Trouble eating: chewing on one side, dropping food, reluctance to eat, or difficulty opening the mouth or swallowing^8,5,2
• Facial swelling or a lopsided face^7,5
• Pain: pulling away when the head is touched⁸
• Swollen lymph nodes under the jaw, which sometimes enlarge before the tumor itself is noticed^2,7
• Weight loss^5,3
• Nosebleeds, if the tumor involves the upper jaw³
• Trouble breathing or swallowing, which can occur with tumors of the tonsils⁹

Signs of Oral Melanoma

Oral melanoma is the most common mouth cancer in dogs. It often appears as a dark (often black or gray) lump on the gums or palate, but some melanomas have no pigment and look pink.^10,4,2 They can look small while extending deep into the bone, causing facial swelling, and they often ulcerate and bleed.^10,8 Dogs with heavily pigmented mouths may be more prone to it, so don't ignore a new or changing dark spot.²

Mouth Lumps That Aren't Cancer

Many growths in a dog's mouth are benign, but they can look very similar to cancer, so a biopsy is the only way to be sure.^2,11

• Peripheral odontogenic fibroma (epulis): a firm, benign gum growth, usually in dogs 6 and older, cured by complete removal^7,2
• Gingival hyperplasia: overgrowth of the gums, common in Boxers and Bulldogs and sometimes caused by drugs such as cyclosporine; it can look like a tumor¹¹
• Oral warts (papillomas): cauliflower-like growths in young dogs, caused by a virus, that usually disappear on their own within a few months^12,7
• Tooth root abscess: swelling below the eye or along the jaw, with pain when chewing¹³

Checking Your Dog's Mouth

Look at your dog's gums, teeth, tongue and the roof of the mouth when you brush their teeth, and have their mouth examined by your vet at least once a year.¹⁴ Be gentle: a dog with a painful mouth may bite.¹⁴ Any new growth, or one that's changing, should be checked by your vet rather than watched.^6,3

Frequently Asked Questions

What are the first signs of mouth cancer in dogs?

Often a lump on the gums, bad breath, drooling, blood in the saliva, a loose tooth or difficulty eating. Some dogs show swollen lymph nodes under the jaw before a tumor is seen.

What does gum cancer look like in dogs?

It may be a dark, pink or red lump on the gums, sometimes cauliflower-like, ulcerated or bleeding. Benign growths can look similar, so a biopsy is needed to know for sure.

What does oral melanoma look like in dogs?

Usually a black or gray lump on the gums or palate, although some melanomas have no pigment and look pink. They often bleed and may cause facial swelling.

Is every lump in a dog's mouth cancer?

No. Epulides, gum overgrowth, warts and abscesses are common benign causes. But because some cancers look harmless, any mouth lump should be checked by your vet.

Can bad breath be a sign of cancer in dogs?

It can. Bad breath is usually caused by dental disease, but strong, new bad breath, especially with drooling, bleeding or a lump, should be checked for an oral tumor.