Signs and Symptoms

• Lumps or Bumps Under the Skin

  • Can form anywhere

  • May be benign or malignant — only a vet can tell by testing

  • Examples:

    • Mast Cell Tumors: pink, hairless, itchy bumps

    • Melanoma: dark patches in the mouth or toes

    • Fibrosarcoma: firm or soft, possibly ruptured

• Foul Odors

  • Bad smells from the mouth, ears, or body

  • Could be a tumor in the mouth (melanoma, squamous cell carcinoma)

• Non-Healing Wounds or Sores

  • Cancer affects immune response → slow healing

  • Sores may appear ulcerated or look like infections

• Loss of Appetite or Weight

  • One of the first warning signs

  • Dogs may eat less, lose strength, or seem uninterested in food

• Digestive Issues

  • Vomiting (especially with blood), diarrhea, bloating, or bloody stools

  • Tumors can cause stomach swelling or blockages

• Coughing or Difficulty Breathing

  • Persistent cough not due to a cold

  • May signal lung tumors or spread of cancer from other organs

• Increased Drinking and Urination

  • May signal metabolic disease or urinary tract involvement

• Trouble Swallowing or Eating

  • May indicate tumors in the throat or neck

• Change in Bathroom Habits

  • Straining to pee or poop

  • Incontinence or frequent urination

• Limping or Signs of Pain

  • Could result from bone cancer or soft tissue sarcoma

  • Dogs may avoid stairs, walks, or play

• Low Energy or Mood Changes

  • Lethargy, sleeping more, avoiding people or other pets

  • Anxiety or aggression can also appear

• Lymphoma

  • Swollen lymph nodes, vomiting, diarrhea, appetite/weight loss, labored breathing

• Anal Gland Cancer

  • Growths near anus, bleeding, pain, straining to poop, difficulty walking

• Bladder Cancer

  • Bloody urine, painful urination, frequent accidents, back pain

• Mammary (Breast) Tumors

  • Large, painful lumps that may bleed or become infected

• Hemangiosarcoma

  • Tumors in spleen, liver, or heart can rupture → sudden internal bleeding → collapse or death

• Liver Cancer

  • Vomiting, diarrhea, weight/appetite loss, jaundice, abdominal swelling

• Melanoma (Oral)

  • Trouble eating, drooling, mouth bleeding, bad breath, facial swelling

• Soft Tissue Sarcoma

  • Large painful masses; may interfere with movement and ulcerate

• Seizures

  • Jerking, foaming at the mouth, sudden aggression, or loss of consciousness

• Behavior Changes

  • Hiding, restlessness, loss of interest, or antisocial behavior,

If your dog shows any of the above signs:

• Visit your local veterinarian immediately for a physical exam and possible diagnostics

• You may be referred to:

  • Internal medicine, dermatology, or surgical specialists

  • Veterinary oncologists if cancer is confirmed

*Treatment options are personalized based on the type and stage of cancer

SASH Vets – 10 Early Warning Signs of Cancer in Dogs

PetMD – Signs a Dog Is Dying of Cancer

Papaya Veterinary Care – Signs and Symptoms of Cancer in Pets