By Dr. Mark Silberman, Southwest Animal Clinic

Cancer is a common canine ailment. It is a killer in dogs, just as it is in humans.  There are predisposing factors that have been identified such as exposure to substances like metals, dust, chemicals or pesticides.  Diet plays a role in the development of cancer, as does exposure to UV light.  Most dogs with cancer are middle-aged to older animals, but the effect of an animal’s age on cancer is not well understood.  Cancer is found in all breeds of dogs even though some have a greater predilection.  This article will concentrate on some of the common breeds and their predispositions to cancer.

In a 1997 Swedish study involving 222,000 dogs, the proportional mortality rate for cancer was 18.6 percent of the recorded deaths in 1993. These high-risk breeds (more than 10 percent dying of cancer) are: Boxer (36.9 percent), Giant Schnauzer (36.9 percent), Bernese Mountain Dog (32.7 percent), Irish Wolfhound (24.8 percent), Cocker Spaniel (22.2 percent), Doberman Pinscher (22.2 percent), Pomeranian (19.0 percent), Newfoundland (16.8 percent), German Shepherd Dog (14.8 percent), Saint Bernard (13.1 percent), Great Dane (12.3 percent), Greyhound (12.3 percent) and Basset Hound (percentage unknown, but the breed does have a genetic predisposition to lymphomas).

The most prevalent tumor location in dogs is the skin with 20 – 30% of these being malignant. Mast cell tumors, Histiocytomas, Squamous Cell Carcinomas and Melanomas are the most common.

Osteosarcoma is the most common primary bone tumor of dogs.  Size rather than breed is considered more of a risk factor.   However, there is a genetic predisposition in St. Bernards, Great Danes, Irish Setters, Dobermans, German Shepherds and Golden Retrievers.

Gender also plays a role.  The most common tumor type in the female is a mammary gland tumor.  In an intact male it would be the testicular tumor (neutering a male dog will eliminate the cancer risk).  But there does not appear to be a breed predisposition to mammary gland tumors.

Lymphoma, a tumor arising from the hematopoietic tissue, is becoming more prevalent in certain breeds and at a younger age.

What follows is a partial list of some popular breeds and their predilections for cancer.  It is interesting to note that there are some breeds with no predilection. 

Airedale – Melanoma, Lymphosarcoma, Pancreatic carcinoma

Alaskan malamute – Sebaceous gland tumor, Anal sac adenocarcinoma

Australian Shepherd – None

Basset Hound – Mast cell tumor, Cutaneous haemangioma, Lymphosarcoma

Beagle – Mast cell tumor, Sebaceous gland tumor, Haemangiopericytoma, Perianal gland adenoma, Lymphosarcoma

Bichon Frise – Basal cell tumor

Border collie – None

Boston terrier – Mast cell tumor, Melanoma, Fibroma, Primary brain tumor

Boxer – Mast cell tumor, Melanoma, Cutaneous haemangioma, Histiocytoma, Sq. cell carcinoma, Fibroma, Thyroid neoplasia, Insulinoma, Osteosarcoma, Primary brain tumor, Lymphosarcoma.

Briard – None

Brittany spaniel – Liposarcoma (Lipoma)

Bull dog (English) – Mast cell tumor, Lymphosarcoma

Cavalier King Charles Spaniel – None

Chihuahua – Melanoma, Testicular neoplasia

Chow – Melanoma, Lymphosarcoma

Cocker Spaniel  – Basal cell tumor, Sweat gland tumor, Trichoepithelioma, Cutaneous papilloma, Sebaceous gland tumor, Plasmacytoma, Histiocytoma, Fibrosarcoma, Perianal gland adenoma, Anal sac adenocarcinoma, Melanoma, Lipoma,

Collie – Sweat gland tumor, Histiocytoma, Haemangiopericytoma, Nasal cavity tumors, Colorectal neoplasia

Dachshund – Anal sac adenocarcinoma, Lipoma, Mast cell tumor, Sq.cell carcinoma, Histiocytoma, Ocular melanoma

Dalmatian – Actinic keratosis, Cutaneous haemangioma

Doberman – Melanoma, Lipoma, Histiocytoma, Fibroma, Myxoma, Primary brain tumor

Fox Terrier – Mast cell tumor, Fibroma, Haemangiopericytoma, Schwannoma, Insulinoma

German Shepherd – Sweat gland tumor, Trichoepithelioma, Anal sac adenocarcinoma, Cutaneous haemangioma, Lymphoma, Myxoma, Nasal cavity tumors, Colorectal neoplasia, Insulinoma, Limbal melanoma, Testicular neoplasia, Thymoma

Golden Retriever – Mast cell tumor, Sweat gland tumor, Trichoepithelioma, Melanoma, Haemangioma, Histiocytoma, Fibroma, Lymphosarcoma, Nasal cavity tumors, Thyroid neoplasia, Insulinoma, Primary brain tumor, Fibrosarcoma

Great Dane – Histiocytoma, Osteosarcoma

Greyhound – None..although beginning to see haemangiosarcoma

Havanese – None

Irish setter – Trichoepithelioma, Sebaceous gland tumor, Haemangiopericytoma, Lymphoma, Melanoma, Insulinoma

Jack Russell – Pituitary tumor

Labrador retriever – Mast cell tumor, Cutaneous histiocytoma, Sq. cell carcinoma, Nasal cavity tumors, Insulinoma, Lymphosarcoma, Limbal melanoma, Oral Fibrosarcoma, Thymoma

Lhasa Apso – Sebaceous gland tumor, Keratocanthoma, Perianal gland adenoma

Maltese – None

Miniature Pinscher – None

Pekingese – Sq. cell carcinoma

Pointers – Mast cell tumor, Haemangioma, Nasal cavity tumors

Poodle – Basal cell tumor, Trichoepithelioma, Sebaceous gland tumor, Sq. cell carcinoma, Insulinoma, Pituitary tumor, Adrenalcortical tumor, Lymphosarcoma, Limbal melanoma, Oral melanoma, Testicular neoplasia,

Pug – Oral melanoma, Mast cell tumor

Rottweiler – Sq. cell carcinoma, Histiocytoma, Osteosarcoma

Schnauzer – Trichoepithelioma, Sebaceous gland tumor, Melanoma, Lipoma, Histiocytoma, Sq. cell carcinoma, Testicular neoplasia, Limbal melanoma,

Scottish terrier – Mast cell tumor, Melanoma, Histiocytoma, Sq. cell carcinoma, Lymphoma, Primary brain tumor

Shar Pei – Histiocytoma, Mast cell tumor

Sheltie – Histiocytoma, Basal cell tumor, Lipoma, Nasal cavity tumors, Testicular neoplasia

Shih Tsu – Sebaceous gland tumor, Perianal gland adenomas

Siberian Husky – Basal cell tumor, Sebaceous gland tumor, Haemangiopericytoma, Perianal gland adenoma, Testicular neoplasia

Springer Spaniel – Trichoepithelioma, Histiocytoma, Melanoma, Anal sac adenocarcinoma,

Weimaraner – Mast cell tumor, Lipoma

Welsh Corgi – None

Westie – Histiocytoma

Yorkshire terrier – Keratocanthoma, Pituitary tumor, Testicular neoplasia

Cancer prevention is not well understood.  In its simplest sense, cancer is a failure of the immune system to check uncontrolled growth of certain cells.  As these cells multiply unchecked, they form tumors.  If the tumors are unchecked, they metastasize.  They send cancer cells all over the body to form more tumors.

There is ongoing research at several universities looking for better treatment options.  Newer strategies include gene therapy, drugs that inhibit the metastasis process and chemotherapy-impregnated implants that release drugs in a slow, steady manner.