Cancer Warning Signs in Dogs
Some of them are very obvious and some are quite discreet

There are several cancer warning signs in dogs and some of them will be very obvious, while others will be very discreet and hard to spot.

However, as an owner, if you understand these warning signs as well as cancer itself, it will be much easier for you to identify them.


This is critical with any disease, but with cancer, identifying it very early can make the difference between a normal life compared to one that may be seriously challenged.

It may also make the difference between life and death in some cases.

Cancer, even with the recent advances, still accounts for over 50 percent of all the deaths in dogs that are ten years old or older.

However, it was not that long ago that if your dog was diagnosed with cancer, it was considered to be an automatic death sentence.

It was only a matter of time before this killer came for your dog.

That has changed drastically in the last few years and the research that is ongoing with both human as well as dog cancer is advancing faster with each passing year.

Because of this, the more you know about the cancer warning signs in dogs as well as what some of the basic terms mean, the better prepared you will be in protecting your dog.


One of the first important steps for any owner in identifying the cancer warning signs in dogs is to understand what some of the basic terms actually mean.

Most owners are not professionally trained, and if you are not, the terms themselves can be frightening without a full understanding.

The first place to start is with the term cancer itself.

Cancer is identified as any malignant or cellular tumor, and these are then divided into two major groups; carcinoma and sarcomas.

The term tumor is defined as a swelling or a cardinal sign of inflammation.

Canaan dogsChippers case proved that not all cases are cancer

A new growth of tissue in which there is cell multiplication that is both uncontrolled and progressive is referred to a neoplasm.

A neoplasm is also a tumor, but the key to this term is abnormal, as well as new. These tumors will then be identified by two other terms; benign or malignant.

The term benign brings immediate relief in an owners mind, but it can still be dangerous.

Benign implies that the tumor is lacking the proper properties to become invasive and metastasis, which refers to the tumors ability to spread.

Benign tumors will also show a lesser degree of abnormality than malignant tumors.

A malignant tumor will cause an owner to react completely opposite, and there is a very good reason for this, but they are still cancer warning signs in dogs.

Malignant tumors do have the properties to be both invasive as well as metastasis, which mean they can and do spread.

They also display cells that have a wide range of varying characteristics, and it this fact that allows them to spread very rapidly in some cases if they are not stopped.

The term carcinoma refers to a malignant tumor or growth that is made up of epithelial cells that can infiltrate the surrounding tissues, and as a result, allows them to metastases or spread.

A Sarcoma is also a malignant tumor that originates either from the connective tissue in your dog’s body, their blood, or their lymphatic tissues.

However, there are still two terms in dealing with cancer warning signs in dogs; a growth or a lump.

A growth refers to any kind of an abnormal increase in the size of tissue in your dog, and a lump implies a growth or fluid filled cyst.

It can also refer to any structure that rises above the normal surface of your dog’s tissue plane, and can also be yet another one of cancer warning signs in dogs.


Cancer warning signs in dogs can appear anywhere on or in your dog’s body as it may be localized, meaning it is confined to one central location.

However, it can also spread and invade both adjacent tissues as well as spread throughout their body.

It is estimated by the medical community that cancer attacks dogs at about the same rate it attacks humans and still accounts for fifty percent of all older dog deaths.

All of the first set of cancer warning signs will involve tumors, with skin tumors being the most common.

All skin tumors in dogs will be either lumps or a mass of some type that appear their skin and can include melanomas, lipomas, as well as basil cell and mast cell tumors.

The next most common sign is with Lymphoma, but in most cases you will not be able to spot this form other than by the symptoms.

This form of cancer affects your dog’s digestive tract as well as their liver.

It will cause vomiting, diarrhea, as well as a yellow tinge to develop in your dog’s gums as well as their skin.

It can also cause your dog to cough, which is the worst warning sound you will ever hear from your dog.

If you ever hear your dog cough other than to clear their throat if they have eaten or drank too quickly, you need to have it checked immediately.

Mammary gland tumors will be the next set of cancer warning signs and are the most common form of cancer in older female dogs that have not been spayed.

It is estimated that over fifty percent of all of the tumors in dogs are mammary tumors, and of these, over fifty percent are malignant.

However, this tumor you can spot as it will begin to appear in your dog’s breast tissue and you can easily feel them if you examine the area on a regular basis.

The next form of tumor that you need to watch for is abdominal tumors, but this is another one you cannot see or feel.

However, you can very easily see the symptoms, as you dog will begin to lose weight for no reason, start to become weak, as well as develop very pale gums.

They will also start to vomit, but it will not be a gagging type of vomiting; instead it will be a protracted form that will be explosive in nature.

There are also two other warning signs to watch for; diarrhea that is persistent, as well as an enlarging of their abdomen or stomach area.

The last of the cancer warning signs that involve tumors will be testicular tumors.

These tumors are the second most common tumors in intact male dogs and these are very easy to identify as your dog will have one normal sized testicle and one that is enlarged.


Cancer warning signs in dogs also have a list of general warning signs that you can watch for.

This list begins with any type of lump or growth that grows very quickly, a firm mass that seems to be attached to an underlying tissue, as well as a pigmented mass.

However, this pigmented mass will also begin to change, and this is yet another sign.

If your dog has a sore or any type of wound that does not heal, a difficult time in eating or swallowing, as well as a loss of weight or appetite, these are also more cancer warning signs in dogs.

However, the list is still not complete, as it also includes any type of repeated vomiting, especially if your dog is in their middle to late ages.

Coughing or any type of labored breathing, bloody urine or a difficulty in urinating, as well as a straining to defecate, are also signs you can watch for.

If your dog suddenly becomes very lethargic, especially if they are normally very active, are also warning signs as is a sudden lameness.


Cancer warning signs in dogs and the symptoms can be very easy to identify if you understand what to watch for, especially as your dog gets older.

What is extremely important for any owner to remember is that just like cancer in humans, early detection can mean the difference between life and death in most cases.

However by no means is it any longer an automatic death sentence.


Rutteman, GR; Withrow, SJ; MacEwen, EG. Tumors of the mammary gland. In Withrow, SJ; MacEwen, EG (eds). Small Animal Clinical Oncology. W.B. Saunders Co. Philadelphia, PA; 2001:455-477.

Sorenmo K. Canine mammary gland tumors. Veterinary Clinics of North America: Small Animal Practice 2003; 33: 573-596.

Mitchener, K. The commandments of cancer care. Presented at the 2002 Wisconsin Veterinary Medical Association Convention, Milwaukee, WI. October 12, 2002.

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