Top Five Signs of Canine Cancer

Canine cancer:  it’s a diagnosis that strikes fear in the bravest of us; so much so that we might want to ignore the warning signs to avoid hearing the word.  This isn’t usually the best strategy, however, as early detection is conclusively linked to longer survival.

Maggie’s Story

My Golden Retriever Maggie was given a clean bill of health by the vet, then two weeks later I found a lump when I was scratching her under her chin.  It had grown enough in two weeks to go from undetectable by a professional to very obvious by a lay person.  Since we caught it so early, the tumor was still encapsulated in the thyroid and hadn’t yet metastasized to anywhere else in Maggie’s body.

For about 75% of dogs, thyroid cancer is not discovered until it is too late to be surgically removed.  Most are then treated with radiation to keep the tumor as small as possible for as long as possible until the cancer spreads to other parts of the body and kills the dog.

Symptom # 1:  Lumps

Probably the most obvious sign of cancer is a new lump.  Your dog can develop benign lumps for various reasons, the most common of which are warts and fatty tumors.

To distinguish between these harmless lumps and those that should be checked out, perhaps the best indicator is the squish factor.  Soft, squishy tumors are quite often harmless and should just be mentioned to your vet at your next visit for confirmation.  Hard tumors should be checked out immediately..

Another important distinction between malignant tumors and benign tumors is the rate of growth.  Benign tumors typically grow more slowly and soon reach a point where they stop growing.   Malignant tumors, on the other hand, are generally fast-growing and they continue to grow until treatment is successful.

Symptom # 2:  Loss of Appetite

Another sign of canine cancer that is fairly easy to spot is a loss of appetite.  If your dog reduces his intake for more than a day or so, it’s a good indication that something is amiss.  Most dogs have a very high food drive, and they are never late for dinner!

Loss of appetite is a common sign of cancer in dogs

Dogs afflicted with cancer may change their eating habits slowly as they become progressively more ill.  This slow change may be a little harder to spot until the cumulative reduction in intake becomes impossible to ignore.

Depending on the location of the dog’s tumor, you may see other changes in eating habits.  For example, a dog who normally eats dry kibble may only be able to eat moist canned food if he or she has a tumor of the digestive tract.  Even if the tumor is in a structure that is simply near the digestive tract, the external pressure on the gastrointestinal organs may be enough to cause similar changes.

Symptom # 3:  Changes in Bowel or Bladder Function

You may see your dog straining to pass urine or solid waste, which is probably the result of a tumor in the bladder or bowel which is blocking the passage of waste.

Another troublesome change in bowel or bladder function is finding blood in the stool or urine.  Tumors are often highly vascularized, meaning that they have a large number of blood vessels per square inch.  This increased blood flow is one of the reasons tumors can grow so quickly.

As the tumor grows and changes shape, some of the blood vessels may become torn or stretched, and they soon begin leaking blood.  This loose blood can be excreted with the dog’s waste if the tumor is located in the digestive tract or urinary tract.

Blood in the urine or solid waste is cause for immediate concern.  Even if the dog doesn’t have cancer, excreted blood indicates a serious problem that should be checked by your veterinarian.

An important note about bloody stool:  the blood may or may not be bright red.  It is very common for the blood to become dried out as it passes through the intestines, giving it the appearance of coffee grounds by the time the dog poops it out.

Symptom # 4:  Difficulty Breathing

Tumors of the respiratory system can cause your dog to have trouble breathing as the tumor takes up space normally devoted to lung expansion.  In addition, any tumor in the chest cavity can prevent lung expansion even if the lungs are not directly involved.  Further, tumors anywhere in the body can grow so quickly that they need a huge amount of oxygen, causing the dog’s respiratory system to struggle to keep up.

You may notice your dog breathing unusually fast, or you may notice your dog’s activity level slowing down to allow more oxygen to feed the tumor rather than the dog’s muscles.  Once your dog becomes a senior citizen, he or she will begin slowing down somewhat, but the lethargy associated with cancer is usually much more pronounced.  And lethargy in a younger dog should be always cause for concern.

If your usually active dog becomes uninterested in his or her favorite activities without any apparent reason, you should suspect illness as the cause.  Most dogs want nothing more than to play with their favorite people.  If they are unable or unwilling to do so, you would be safe in assuming something is wrong.

Symptom # 5:  Sores That Won’t Heal

Skin cancer is one of the most common cancers to afflict dogs, and the cardinal sign of a skin tumor is a sore that refuses to heal. Your dog may or may not worry over the spot, licking it whenever he or she can.  If the dog isn’t constantly licking the sore, you may have trouble spotting it, particularly if your dog has long hair.

Spend some time at least once a month pushing aside the dog’s hair to see the skin.  Look for areas of color change or scaly, crusty spots.  You might also find small skin lesions that bleed easily or any kind of discharge from a spot on the skin.  Any of these signs are worth of a vet visit.

Even if none of these signs are present, if you find a spot that looks different from the skin surrounding it, keep an eye on it to see if it changes.  If so, bring it to your vet’s attention as soon as possible.

Defeating Canine Cancer

You might want to find out how you can help fund research for canine cancer.  The Morris Animal Foundation is trying to raise $30 million dollars to fund canine cancer research, and Chase Away K-9 Cancer is one pet parent’s response to her dock-diving dog, Chase’s, death.  You can donate online, or if you ever attend a national Dock Dogs event, you can slip a few dollars into one of the dogs wearing the bright yellow vest.

Cancers of different systems will create different signs and symptoms, so it’s important you spend enough time with your dog to see changes in his behavior, habits, and health while any related tumors are small and easier to treat.  The five symptoms covered above will give you a start, and more information can be found in our doggie den series on canine cancer and in our doggies.com blog post about canine cancer.