Cancer is one of the leading causes of death in dogs and cats. Early detection is key to a better outcome. Here are 10 warning signs of cancer. If you notice one or more of these signs, you should take your pet in to see your local veterinarian.

• Swollen Lymph Nodes
  These glands are located throughout the body but are most easily noticed under the jaw or behind the knee. When lymph nodes are enlarged, they can suggest several illnesses including infections or a common form of cancer called lymphoma. A biopsy or an aspirate from these swollen lymph nodes can aid in obtaining a diagnosis.
  

• Enlarging or Changing Lump or Bump
  Any lump that is rapidly growing or changing in texture or shape should be examined. A biopsy or aspirate can aid in determining if it is benign or malignant.
  (Also read about:  Basal Cell Carcinoma, Canine Mammary Gland Tumors, Histiocytic Sarcomas, Mast Cell Tumor, Melanoma, Soft Tissue Sarcoma, Squamous Cell Carcinoma)
  
  
• Distended Abdomen
  When the belly becomes rapidly enlarged or distended, this can suggest several problems including a mass or tumor in the abdomen or fluid accumulation including bleeding in the abdomen. A radiograph (X-Ray) or an ultrasound of the abdomen are often recommended to help in diagnosing the problem.  
  (Also read about: Hemangiosarcoma)
  
  
• Weight Loss
  Unexplained or chronic weight loss in a pet (that is not on a diet) should be examined and checked for illnesses that can lead to weight loss. Although it's not a specific sign in pets with cancer, it can indicate that something is wrong. Many cancer patients do have weight loss while others do not. Weight loss can also be seen in pets with gastrointestinal, liver and kidney disease.
  
  
• Vomiting or Diarrhea
  Unexplained chronic or intermittent vomiting or diarrhea should prompt further investigation. There are many causes of vomiting and diarrhea - cancerous and non-cancerous conditions. Tumors of the gastrointestinal tract can often cause chronic vomiting and/or diarrhea. Radiographs (X-Rays), ultrasound, endoscopy and laboratory tests are useful diagnostic tools to help in determining the cause.
  
  
• Unexplained Bleeding
  Bleeding from the mouth, nose, gums, or blood in the urine or stool, that is not due to obvious trauma should be examined. Bleeding disorders do occur in pets and can be life-threatening. There are cancerous and non-cancerous causes of unexplained bleeding and a thorough search of the cause should be undertaken.
  
  
• Cough
  Chest radiographs (X-Rays) should be taken in older pets with a dry, non-productive cough. Although there are various causes for coughing in pets of all ages - including anatomic problems, allergies and infections - this type of cough is the most common sign of lung cancer in older pets.  
  
  
• Lameness
  Unexplained lameness or limping, especially in large or giant breed dogs, is a very common sign of bone cancer. Radiographs of the affected area are very useful for detecting bone cancer or other diseases of the bone. If bone cancer or an infection of the bone is suspected, a biopsy may be recommended to obtain a diagnosis. (Read about Chondrosarcoma)
  
  
• Straining to Urinate
  Straining to urinate or blood in the urine are usual signs of a urinary tract infection. However, if the straining or bleeding do not resolve rapidly with antibiotics or if they are recurrent, urinary bladder stones or bladder cancer may be an underlying cause. Radiographs, ultrasound and cystoscopy are all techniques that allow the veterinarian to examine this area in detail. With cystoscopy, a biopsy can be taken non-invasively to help in establishing whether bladder cancer is the cause.
  
  

• Bad Breath

  A foul odor from the mouth can be noticed in pets with moderate to severe dental or gum disease and in pets with tumors of the oral cavity, nasal passages or sinuses. Dental disease and oral tumors can also cause a pet to change their food preference (from hard to soft food) or cause a pet to change the way in which they chew their food. A thorough examination by a veterinarian is warranted. The veterinarian may recommend radiographs of the head or teeth, and in some cases a CT scan may be recommended, to determine the underlying cause or extent of disease.