Guide to Canine Cancer
Table of Contents
Canine cancer is the result of cell growth
which is uncontrolled and that serves no purpose. Cancer in dos is also
referred to as a neoplasia, tumor and malignancy. Any body tissue can
develop cancer. Cancer either originates at a site, which is called
primary cancer or spreads from another area, which is called secondary
cancer. Cancer spreads in the body through the blood or the lymph
system, with lymphomas being one of the most common cancers in dogs.
Estimates indicate that as many as 1 in 3 dogs will develop lymphoma.
Once a cancer starts to spread it becomes increasingly more difficult to treat (called cancer that has metastasized). Treatment for specific types of cancer in dogs can be found by clicking on the links below for each specific type ."
Video on on Treating Dog Cancer and Tumors
Hearing that your dog has canine cancer does not mean the end of its life. Like cancer treatment in people, there are now many options for treating your pet. In general, treatments tend to be more effective and have fewer side effects. Cancer is seen in about 1,100 of every 100,000 dogs and is treated by a veterinary oncologist.
Cancer is often referred to as a tumor, which is any sort of lump of bump. Tumors that grow are called neoplasms. There are two types of tumors:
- Benign: Tumors that grow slowly and don’t spread to other parts of the body are considered benign as they have not metastasized or spread. A benign tumor is treated with surgery.
These tumors are the same as cancer and are also called carcinomas,
sarcomas and lymphomas depending on where the cancer is on the body. As
the cancer spreads from one part of the body to another, it can enter
the lymph nodes or circulatory system. The spread is called
Types of Canine Cancer and Tumors
- Dog Neoplasia Overview
- Anal Gland Tumors
- Bladder Cancer
- Breast Cancer
- Bone Cancer
- Benign Bone Tumors
- Intestinal Cancer
- Kidney Cancer
- Alternative Treatment Options - Leukemia and Other Cancers
- Liver Tumors
- Lumps and Bumps on Skin
- Mammary Cancer
- Multiple Myeloma
- Prostate Cancer
- Prostate Cancer in Dogs
- Skin Cancer
- Spleen Cancer
- Stomach Cancer
- Thyroid Cancer
What is Canine Cancer?
In a normal dog cells are constantly dieing and being replaced. In a dog with cancer, something is wrong with the replacement cells (called mutant cells). These mutant cells reproduce quickly and form into large groupings. Since these cells are mutant, they cannot provide the same function as the healthy cells they replaced. If these cells or cancer grows, it eventually replaces healthy tissue and causes the dog to die.
Tumors on Dog Leg
Mast Cell Neoplasia on Legs of a Sharpei
High Risk Breeds for Cancer
Basset Hound – Trichoepithelioma
Kerry Blue Terrier – Pilomaticoma
Cocker Spaniel – Ceruminous Adenoma
English Cocker Spaniel – Anal sac gland carcinoma
Giant Schnauzer and Gordon Settler – Subungual squamous cell carcinoma
Vizsla and Miniature Schnauzer – melanocytoma
Shetland Sheepdog – liposarcoma
Boxer and Pug – Mast Cell Tumor
Cocker Spaniel – Cutaneous Plasmacytoma
- Bernese Mountain Dog* - greatest incidence of cancer in a 20-year
study of nearly 75,000 dogs
- Golden Retriever*
- Scottish Terrier* – Subungual malignant melanoma
- Bouvier des Flandres*
- Irish Setter*
- Airdale Terrier*
- Gordon Setter*
* According to a study in the Journal of Veterinary Internal Medicine that reviewed causes of death for nearly 75,000 dogs from 1984 to 2004, breeds where cancer is more common (in descending order, asterisk breeds only).
There are several early warning signs of dog cancer symptoms:
- Unusual swelling that continues to grow
- Sores that do not heal
- Weight Loss
- Loss of appetite
- Offensive odor, especially from the mouth
- Bleeding or discharge from any body opening
- Reluctance to move or exercise, loss of stamina
- Difficulty eating or swallowing
- Loss of energy
- Difficulty breathing, urinating or making a bowel movement
- Sleeping more than usual
- Persistent lameness or stiffness
Dog Cancer Symptoms Example
Akita pup with fibrosarcoma
Symptoms Requiring Emergency Treatment
Your dog has collapsed
Bleeding after receiving chemotherapy
Loss of appetite while undergoing treatment
Symptoms Requiring a Call or visit to your
- Skin – Sores, bumps, lumps
- Leg – Large breed with swelling or a limp
- Seizure - In older dog that has a
seizure (uncontrolled shaking) for the first time
- Nose – blood coming from the nose
- Mouth – Lump, bump or growth
- Breast – lump or swelling
For more information visit our guide to cancer symptoms.
Determining if your dog has cancer usually requires more than blood tests or x-rays. Your Veterinarian will need to take a sample of the area in question (a biopsy) and send it to a laboratory to test for the presence of cancer. Cancer cannot be diagnosed visually since an examination of individual cells is necessary. If cancer cells are found (called malignant), your entire dog will need to be examined since many types of cancer can spread.
Testing will help the veterinarian classify the stage of development the tumor is in. Each stage is associated with a specific treatment protocol or plan and indicates a dog's prognosis (course and outcome of the disease).
Dog Cancer Diagnostic MRI
Advanced Diagnostic Tests Such as a MRI (shown) Are Used to Diagnose Cancer in Dogs
Tests for Canine Cancer
Even with the advanced canine cancer tests listed below, it is still possible to miss a small tumor.
- Biopsy – The removal of a small sample (non-excisional) or an attempt to completely remove a cancerous mass (excisional). The biopsy is sent to a lab for analysis. A veterinarian may remove an entire lymph node to see if cancer has spread or if cancer of the lymph nodes exists.
- Fine-needle Aspiration (FNA) – Like a biopsy, but instead of surgery, a needle is used to extract cancerous cells for testing.
- Blood Tests (CBC) – There is no blood test for
cancer. Changes in the composition of blood could indicate problems
such as low red blood cells, high white blood cells or changes in
kidney and liver function. These test are called a chemistry
profile and blood count.
- X-Ray – An x-ray will detect tumors in
the lungs, chest or bones.
- Ultrasound – The best technique for detecting tumors in the abdomen. A biopsy would be needed to confirm any findings.
- Endoscopy – A video camera on a thin tube that is inserted into the mouth or nose to look for tumors. Used to examine the colon, bronchi and stomach.
- Surgery – To examine any area in question.
- CT/MRI Scans – Best technique for detecting tumors that are near bone are unable to be seen by X-rays.
- Urinalysis- to check urine components
- Bone Marrow Aspirate - the removal and testing of bone marrow
- Lymph Node Aspirate - the removal of lymph node fluid
- Immunologic Studies - testing immune response
Tumor Node Metastasis Rating System
A veterinary oncologist will use a ratings system that defines the size and spread of a tumor.
- Tumor Size or Extent (T=Tumor)
- Tis: preinvasive tumor (in situ)
- T0: no evidence of tumor
- T1: tumor <5 cm in diameter but confined to primary site
- T2: tumor >5 cm in diameter or ruptured tumor
- T3: infiltrative tumor
- a: no bone invasion
- b: bone invasion
- N = nodes
- N0: no evidence of lymph node enlargement
- N1: movable ipsilateral nodes enlarged
- N2: movable contralateral/bilateral nodes enlarged
- N3: fixed nodes
- M = metastasis
- M0: no metastasis
- M1: metastasis detected
If a tumor has spread (metastasized) in most cases a cure is
not possible. In these cases the purpose of dog cancer
treatment is to focus on maintaining a dog's quality of life
(this is called palliation). Palliation or palliative care seeks to
minimize pain and reduce any functional difficulties such as urination
Tumors that have not spread (referred to as being localized) have the best prospects for being cured. Treatment usually involves some combination or single use of immunotherapy (improving the immune system), surgery, chemotherapy or radiation. Curative approaches are commonly used if the tumor can be controlled for one year or longer after the start of treatment.
For example, radiation can be used to shrink a tumor followed by
surgical removal of any remaining cells.
Radiation Therapy is Used to Treat Cancers Such as Brain Tumors, Nasal Cavity Tumors, Thyroid Tumors, Soft Tissue Sarcoma and Mast Cell Tumors
Treatment approaches for canine cancer:
- Cancers commonly treated with surgery include:
- Mammary tumors (except inflammatory mammary cancer) - most
prevalent tumor in female dogs.
- Prostate tumors
- Oropharyngeal tumors
- Skin cancers
- GI tumors
- Lung tumors
- Bone tumors
- Surgery can have complications with risk increasing based on the age of the dog. Complications include incomplete healing, blood loss, wound infection and the formation of abscesses. There is also a risk of death caused by the surgery itself.
Radiation therapy is used for many types of tumors.
- Cancers treated with radiation:
- Brain tumors
- Small pituitary tumors (can be curative)
- To extend the survival time for spinal lymphomas and intracranial tumors
- Nasal cavity tumors
- Mast cell tumors
- Soft tissue sarcomas
- Thyroid tumors
- Downsides include the possibility that the radiation will not reach cells in the center of the tumor. The radiation may effect surrounding skin or the lining of the gastrointestinal tract. Can also cause blindness or organ malfunction.
Chemotherapy is used to treat systemic cancers as the sole agent (see list that follows). It is also given to patients that have successfully completed surgery and/or radiation as an additional therapy. Chemotherapy can improve the effectiveness of radiation therapy while helping to slow down tumor growth.
When used in combination with surgery, chemotherapy can reduce tumor size before surgery. Other benefits include the ability to kill microscopic cells and to slow down tumor growth.
Canine cancers treated with chemotherapy include:
- hematologic malignancies
- metastatic carcinomas
- Metastatic sarcomas
Hyperthermia is considered to be the most effective treatment approach when used in combination with chemotherapy or radiation. It is used to treat tumors that are small (<1.0 cm) or malignant and superficial.
The limitations of hyperthermia canine cancer therapy includes that it can damage both normal and cancerous cells. It can also cause skin burns. Like other treatment methods, hyperthermia can be used in combination with radiation and chemotherapy.
With radiation, hyperthermia can double the response to therapy. It can improve survival teams by improving the rate of response to therapy. With chemotherapy the hyperthermia improves that performance of medications that work better at higher body temperatures. It may also protect normal cells against the toxicity of the chemotherapy agents. That said, other studies indicate that the combination of hyperthermia and chemotherapy might increase treatment toxicity.
PDT Canine Cancer Therapy
Photodynamic Therapy (PDT) is used in dogs with superficial, minimally invasive and localized tumors
Photodynamic Therapy (PDT)
Photodynamic therapy for canine cancer is used in a limited number of instances. It is primarily used in dogs that have local (limited to one area) and superficial tumors that are minimally invasive. This includes tumors that are on the lining of the urinary bladder, oral cavity and skin.
Limitations of this type of therapy includes the inability of light to deeply penetrate into the skin or tumor tissue. The dog patient must be kept in reduced lighting conditions for 4 to 6 weeks after treatment. Not all tumors react the same way to treatment.
There are four types of gene therapy available to treat dogs:
- Drug resistance gene therapy
- Tumor suppressor gene therapy
- Genetic immunotherapy
- Suicide gene therapy
These medications work by cutting off the blood supply that "feeds" a tumor. These medications are in the early development stages.
Immunotherapy uses immune system processes to attack cancer cells. Types of cancer treated include:
- Soft tissue sarcomas (includes hemangiosarcoma and fibrosarcoma)
- Growth factors
- Antibody therapy
- Adoptive cellular therapy
- Nonspecific immmunomodulators
There are several alternative therapies that can help to reduce pain and other symptoms such as nausea and vomiting. These include:
- for pain relief any vomiting and nausea that are side effects of chemotherapy and other treatment protocols
- In cases where the massage will not interfere with treatment
- Herbal Remedies
- An oncologist might recommend products like C-Caps to
strengthen the patient or to address any side effects. If a dog is
undergoing chemotherapy or radiation, check with your veterinarian to
ensure that products like these can be used.
If a therapy is not available, then some dogs can be enrolled in a testing trial at a veterinary college. A list of universities that are conducing canine cancer trials can be found at the Worldwide Association for Professionals in Veterinary Oncology.
Nutrition and Diet
In cancer patients, nutrition plays a dual role. It is most important to keep a patient healthy and nourished (to avoid a condition called cancer cachexia, which refers to severe malnutrition in cancer patients). Secondly, it is believed by some that some nutrients can help to slow down or prevent cancer. Other nutrients may be able to reduce the side effects of radiation and chemotherapy.
In general, a dog cancer diet includes an increase of protein and a
decrease in carbohydrates (carbs or glucose might fuel cancer cells).
Other nutrients such as some vegetables, fruits and supplements can
have a positive effect.
The problem for dogs is when the cancer alters the metabolism. This
tends to happen during the early stages of cancer and will decrease the
dog's quality of life over the course of the disease.
See our guide to formulating canine cancer diets for details on all aspects of nutrition and canine cancer diets.
Dog Cancer Treatment Podcast
Here is a helpful podcast on cancer treatment in pets from the American Veterinary Medical Association. The podcast features Dr. Erika Krick, assistant professor of oncology at the University of Pennsylvania School of Veterinary Medicine. The discussion reviews recent development in canine cancer treatment.
Should You Treat a Dog with Cancer
Cancer therapy can require a big commitment from an owner
including multiple trips to the veterinarian and related costs.
These are decisions that can only be made by a owner.
There are five criteria that are used to measure quality of life and
canine cancer care. Dogs that score near normal on each factor tend to have
better treatment outcomes.
- elimination of bodily fluids
- level of activity and exercise
- weight and condition of the body
- alertness and mental status
If you decide to not treat the cancer, the focusing on care using alternatives and conventional approaches (called palliative care) for keeping a dog free of pain may be the best approach. For example, products natural remedies such as C-Caps contain antioxidants which help to strengthen healthy cells and boost a dogs immune system. Again, these types of approaches are considered to be supportive vs. a specific cure.