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Signs of Cancer in Dogs | Pupford

December 6th, 2023

Filed under Health + Wellness

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Just like humans, our pets can experience illnesses. With so much information on the internet about symptoms, signs and preventative measures, it’s important not to get too caught up in it all and make yourself crazy worrying about every little dog sneeze. However, we all understand how important it is to take specific actions and have the necessary knowledge to ensure the safety and health of our furry best friends!

In this article we’ll discuss the common types of cancer for dogs, signs to look out for and how to best prevent these illnesses.

This should only be meant as as a general guide. It is by no means comprehensive. Please consult your vet with specific questions or health concerns.



This type of cancer invades the blood vessels and is a common cancer found in dogs, resulting in about 5% of cases. It can develop anywhere on a dog, but most commonly is found on the skin, spleen, heart, and liver. It is mostly seen in middle to older aged dogs and can occur in any breed but is most common in German Shepherds, Golden Retrievers and Labradors.

Common Symptoms of HSA:

  • Weakness, collapse
  • Lethargy
  • Pale gums
  • Mass under skin (in cutaneous hemangiosarcoma cases)

If the tumor has ruptured, your dog could experience more severe symptoms of weakness, lethargy etc. The most common treatment for this type of cancer is surgery. 1-3 months following surgery, the cancer could spread to other parts of the body, so chemotherapy is often delivered.


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Canine Lymphoma is very similar to non-Hodgkins Lymphoma in people. Lymphoma is a blanket term used to describe different cancers that stem from the lymphocytes. There are over 30 kinds of lymphoma which all vary in signs, aggressiveness, and survival rate, but multicentric lymphoma is the most common and makes up around 80% of all lymphomas. The most obvious manifestation is an enlargement of the lymph nodes.


Larger breed dogs are more at risk for this type of cancer that originates in the bones and bone marrow. Osteosarcomas are highly aggressive and cause painful bone destruction where the tumor is growing.

Signs of osteosarcoma can be hard to identify, but can include swelling that increases over time, degrees of lameness, irritability, loss of appetite, aggression, weight loss, sleeplessness, and decreased physical activity. If you notice any swelling, or if your pup is having a very hard time breathing during exercise or play time, contact your veterinarian right away!

Treatment differs on a case by case basis and your veterinarian would be able to discuss your options in-depth with you.


In dogs, Melanoma most often is found on the skin, in the mouth, on the digits, or around the nail bed. Usually it will present as dark, raised masses on the skin or mouth, but can also appear as a pinkish color. If your dog has melanoma in the mouth other signs include excessive drooling, bad breath, bleeding, pain, and difficulty eating.

Most of the time melanoma is benign, but melanoma in the mouth or around the nail beds/digits can be malignant and spread to other parts of the body. shows on your pup in the form of small, dark lumps or even large wrinkled areas on their skin.

Common treatments include surgery and/or radiation therapy.


Neutered female dogs have a lower risk for this form of cancer. It is very common in non-spayed female canines and experts from National Canine Cancer Foundation recommend “Spaying females before 2 to 2 1/2 considerably reduces the risk of both benign and malignant tumors.”

Symptoms of mammary carcinoma can include pain, ulceration, inflammation in the overlying skin, edema, redness, and more.

Treatment will depend on the stage that the disease is in, but surgery is the most common form of treatment.


According to the Flint Animal Cancer Center, here are the recommended signs you should watch for early diagnosis and treatment:

  • Sores: Open wounds that are not healing at a normal pace.
  • Unusual swelling that has grown or has not gone down in a few days
  • Lumps or bumps that are enlarging over time
  • Weight loss and loss of appetite
  • Discharge of any part of the body (mouth, anus, nostrils)
  • Bleeding
  • Excessive diarrhea
  • Excessive vomiting
  • Bad odor (coming from the mouth, nose or anus -- this can be caused by tumors)
  • Decrease in stamina and willingness to play or exercise
  • Issues with breathing such as wheezing
  • Issues with going to the bathroom such as straining to urinate or poop.

If your pup is experiencing one or more of the above symptoms, they require an immediate trip to their vet!

Related Reading: Pet Insurance 101 - How to Choose Pet Insurance


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First, it’s important to note that not all cancers can actually be prevented. While nutrition and exercise are VERY important to help your pup be happy and healthy, it’s not a sure fire way to prevent any sort of illness. So having awareness of these types of cancers, the signs and understanding when to take action is so important.

For more tips on keeping your pup safe in emergencies and in life in general, check out our course in Pupford Academy, the Dog First Aid Course. Taught by Shelby Baden, Doctor of Veterinary Medicine, this course covers what to do in case of an emergency, how to know if there is an emergency, DIY remedies, dog CPR, preventatives, and more. Check out the course now!

And speaking of safety, learn about emergency preparedness for dogs here.


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