Web Only Article January 22, 2019

Signs of Cancer in Dogs

What are the most common types of cancer in dogs, and what are the signs? Early detection of cancer in your dog makes all the difference in his or her prognosis.

Cancer is a word that strikes fear in the hearts of dog owners. As human cancer deaths rise in the United States, you may wonder if a similar phenomenon is happening in our canine companions. According to veterinary oncologist Dr. Stacy Binstock, estimates show that 25%-33% of dogs will have cancer at some point in their lives. It is the number one cause of death in older dogs. Those are sobering statistics. The good news is that you can help with early cancer detection and early treatment of your dog.

The first step is semi-annual or annual examinations with your veterinarian. These are not just vaccine appointments. A visit is needed for a thorough physical examination. Your veterinarian will check your dog’s weight, vitals, lymph nodes, heart and lungs, palpate the abdomen, and perform a rectal exam. These are all essential to early detection of illness. Weight loss may be the first sign and can be easy to miss at home. Secondly, as your dog ages, your veterinarian will likely recommend bloodwork, urinalysis, and other diagnostics. These can detect changes in organ function, possibly indicating cancer.

dog getting examined by vets

E+/ hoozone

Types of cancer in dogs are varied and include skin, orthopedic, blood, and bone malignancies. As a result, the symptoms differ wildly and depend on which system is affected. The four most common cancers and their clinical signs are listed below.

senior dog sleeping in vet hospital

iStock / Getty Images Plus/ Obradovic

Lymphoma. This is a frequently diagnosed cancer in dogs. It can originate in the lymph nodes, bone marrow, or organs like the spleen. The first signs may be very vague and often include large knots that are palpable under the jaw, behind the elbows, and behind the knees. These are all locations of lymph nodes that can enlarge with cancer. Other symptoms may include lethargy, weight loss, and increased drinking and urinating.

Osteosarcoma. This is a type of bone cancer seen often in large breeds such as Great Danes and Wolfhounds, although it can occur in any breed. Osteosarcoma typically grows silently at the end of a bone (called the diaphysis) until the bone is severely weakened. Early symptoms may include swelling and tenderness. Often, there are no symptoms until the tumor destroys the bone enough to cause a fracture. When this happens, your dog may suddenly be unable to walk on the affected leg and demonstrate signs of severe pain.

dog with mast cell tumor getting shaved for surgery

iStock / Getty Images Plus/ Chalabala

Hemangiosarcoma. Another type of cancer that often has no obvious clinical signs is hemangiosarcoma. These tumors can grow anywhere—on the skin or in the spleen, liver, or other internal organs. In dogs, it is most frequently encountered in the spleen, liver, or heart. Usually, no signs are noted until the tumor grows very large and ruptures. This sudden, catastrophic rupture leads to internal bleeding, weakness, and collapse.

Mast cell tumor. Boxers are especially prone to these skin malignancies. Mast cells are normally found in the skin and react when an allergen is introduced. They are filled with histamine and other substances that are released in an allergic reaction, leading to the formation of hives. Unfortunately, cancer can arise from these cells. The hallmark of an MCT is a growth on the skin that waxes and wanes in size and character. They can be small and “quiet,” or they can become large, inflamed, and weep fluid.

Always observe your dog carefully for any changes. Any skin masses or lumps that you palpate should be checked out by your veterinarian sooner rather than later! Remember, early detection is critical in catching and treating cancer.

Comments (5)

My sweet Chocolate Labrador jsut turned 12 years old. At 6 1/2 years, he was diagnosed with a Mast Cell Cancer (Mastocytoma) on the abdominal wall wich spreads to lymph nodes in both groin. He had a surgery (taking out the tumour and the nodes...) and 6 cycles of CHEMOTx (which he tolerates very well...). He's perfectly fine since that period. No relapse. Enjoys life with a few "old dog problems" (cataracts, lipomas, ...). Glad we decided to treat him !...

Posted by: Jocelyn | February 24, 2019 10:48 PM    Report this comment

I lost my 17 year old English Shepherd to an inoperable nasal cancer. She had no signs that I saw until one day she started sneezing blood. I got her to the vet immediately, but he cancer was right between her eyes and the vet said he couldn't operate and she would let me know when it was over. Three months later she sneezed out a lump of what looked like a bloody pink fungus the size of a large egg and seemed to feel much better, but it didn't last. Just as he predicted, one morning she didn't want to get up and he and I cried together when he euthanized her. I don't recognize any of the descriptions above as matching her symptoms.

Posted by: peppersmum | February 24, 2019 1:07 PM    Report this comment

Mast cell tumors are also common in Boston Terriers, Frenchies and other dogs than Boxers. It's a good idea to just look your dog over from head to toe, run your hands over their body and check for lumps on a regular basis. That way if there is anything suspicious, you can find it before it is there too long.

Posted by: puppypig | February 24, 2019 12:03 PM    Report this comment

Lost my chow mix to lymphoma last spring. She had not been herself for several weeks, but multiple exams by more than one doctor in her vet practice, a complete series of blood tests, and even a total body x-ray showed no sign of what was wrong. Two days before she died, her vet and I were finally able to feel lumps. They were sent for biopsy, but she passed before we even got the confirming results.

Posted by: Rainy's Mom | February 24, 2019 11:43 AM    Report this comment

I would like to know if lung cancer is often found in dogs? Our 13 year old Border Collie was diagnosed with Kennel Cough originally because it was going around in our area. Given antibiotics and seemed to recover, but the cough, runny nose and watering eyes came back. We were in our winter place and went to a differs Vet Clinic, and after Blood work, and X-rays the lung cancer was discovered. Besse
The irony of this is she has me E been around smokers. But after three years of smoke from forest fires, I feel this may have been a contributing factor. Pat Gebbie & Besse Border Collie

Posted by: Besse | February 24, 2019 11:01 AM    Report this comment

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