Merck Manual

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Possible Signs of Cancer

Possible Signs of Cancer

Various changes in a pet’s behavior or appearance, such as those listed below, might indicate the development of cancer. These are not always signs of cancer; however, paying attention to such changes and bringing them to the attention of your veterinarian as soon as they occur can increase the chance that a cancer will be detected and treated at an early stage.

  • A growing or changing lump

  • Swollen lymph nodes

  • Sudden abdominal swelling

  • Unexplained bleeding from the mouth, nose, or genital area

  • Difficulty when breathing, chewing, swallowing, urinating, or defecating

  • Persistent sores or swelling

  • Unexplained bad breath or other odor

  • Dry cough

  • Lowered stamina

  • Recurrent vomiting or diarrhea

  • Loss of weight or appetite

  • Lack of interest in physical activities

  • Indications of physical discomfort, such as lameness or stiffness