So many people know about tumors and cancer from personal experience with friends, family, themselves and/or their pets.  Since we work with cancer regularly in our patient population as well, I thought this post would be good to share for people to understand the process (whether in humans or pets).

What is a tumor?

A tumor is the uncontrolled growth of abnormal cells.  A tumor begins when normal cells in a body mutate into abnormal cells which, instead of following the normal cell process of reproducing, maturing and dying, just keep reproducing without ever maturing or dying.  So they keep growing, forming a mass known as a tumor.

If the tumor remains localized in the tissue in which it started, the abnormal cells are considered benign, which means “harmless”.  They’re abnormal, but they don’t spread anywhere.  So if a benign tumor is surgically removed, the problem is usually solved.  Benign tumors are common, however, to form anew in the same part of the body or in different parts.

If the abnormal cells are NOT benign that means they have either spread to surrounding tissue or they have traveled through the bloodstream or the lymphatic system to other parts of the body to establish colonies of new tumors – they are considered malignant.

Malignant cells are what we call cancer.  Their process of invasion and spread is called metastasis.

What Causes Tumors and Cancer?

Tumors and cancers used to be diseases of old dogs, and they still account for almost half of all canine deaths over age 10.  But today an alarming number of young dogs are developing cancer.  Why?

First, because the tendency for cells to mutate can be inherited – and the unwise breeding practices that are so popular today (breeding related dogs together) have caused these kinds of faulty genes to become widespread in the purebred population.

Second, because canine immune systems are much weaker today than they used to be, and a weak immune system is unable to prevent mutated cells from spreading.  Again, weak immune systems are perpetuated by unwise breeding practices, along with poor nutrition, excessive vaccinations, over-use of drugs and medications, and the increasing presence of toxic chemicals in our dogs’ environments.

What are the symptoms of a tumor?

A tumor can start in virtually any cell in your dog’s body – skin cells, lymph gland cells, bone marrow cells, bladder cells, blood vessel cells, mammary gland cells, etc.  Some tumors develop so deep inside the body that they cause vague symptoms that are hard to detect and recognize.  Some tumors present themselves as a growth, either attached to your dog’s skin like a wart or raised lesion (spot/bump), or under the skin as a lump or mass.

Remember – don’t panic if you see or feel a growth on your dog as this is not always a tumor! Sebaceous cysts, fatty lipomas, and warts are all very common growths on dogs.  These are not tumors (as they are not formed by normal cells mutating into abnormal cells).  But if you do notice any mass that is getting larger, it’s good to have the area checked by your Vet.

What are the most common tumors and cancers in dogs?

Adenoma and adenocarcinoma:

An adenoma is a benign tumor formed by glandular tissue cells almost anywhere – such as in the sebaceous glands, mammary glands, anal glands, thyroid gland, lungs, kidneys, liver, intestines, prostate, nasal cavity, etc.

One common form of adenoma is a sebaceous gland tumor, which appears as a warty growth around a hair follicle.

Another form of adenoma is a perianal tumor which appears as a lump in the anal region, usually in older male dogs who have not been neutered.  Testosterone stimulates anal tissue into developing adenomas – if you neuter your dog when young, he is unlikely to develop an adenoma later in life.

Another common form of adenoma is a mammary gland tumor, which forms a lump in the breast, usually in older females who have not been spayed or who were spayed later in life.  Estrogen stimulates breast tissue into developing adenomas – if you spay your dog before or just after her first heat cycle, she is unlikely to develop an adenoma later.

Unfortunately, there is also a malignant form of adenoma called adenocarcinoma – and it is one of the most aggressive cancers in dogs.  A mammary gland tumor as about a 50-50 chance of being a benign adenoma or a malignant adenocarcinoma.

Other common tumors and cancers in dogs:tumor in schnauzer

Basal Cell tumor and basal cell carcinoma (small skin cells involved), Epulide (most common benign oral tumor), Fibroma and fibrosarcoma (in fibrous tissue of a bone), Hair Follicle tumors, Hemangioma and heangiosarcoma (blood vessels effected), Histiocytoma and histiocytic sarcome (white blood cell related), Lymphoma or lymphosarcoma (in lymphatic system – one of the most common cancers in dogs), Mast Cell tumor and mastocytoma (accounts for about 20% of skin tumors), Melanoma (in pigment-producing skin cells), Osteosarcoma (most common bone cancer in dogs), Sertoli cell tumor (testicular tumor – highest risk is in those with an undescended testicle), Squamous cell carcinoma (on skin, on toes most common in large black dogs including Giant Schnauzers), Transitional cell carcinoma (bladder cancer – very aggressively malignant).


Simplest test is a fine-needle biopsy, where a needle is inserted into the growth and a bit of its contents are aspirated into a syringe and then examined on a slide under a microscope.  For some tumors and potential cancers, blood tests, ultrasounds and x-rays may be needed.


Many benign tumors can be left alone.  Chinese medical herbs may help shrink some of these.  If a benign tumor is making your dog uncomfortable or if it is interfering with some important body function, it can be surgically removed.

For malignant tumors, Western medicine recommends the same options as they do for humans: surgery (including amputation if necessary), chemotherapy and radiation.

Surgery may indeed be the best option for malignant skin tumors, which can usually be removed cleanly and completely when caught early.  And amputation may be the only way to control the pain of some cancers such as osteosarcoma… at least for the short run.  But it is my opinion that chemotherapy and radiation often damage your dog’s immune system and his/her quality of life. Some cancers do respond to aggressive chemotherapy or radiation by shrinking (or going into remission) – for a few months or a year.  Unfortunately, many return, requiring higher doses or stronger drugs to forced them back into remission and after a few cycles, the cancer often becomes resistant.

Naturopathic options do exist for keeping your dog’s immune system at its full strength.  I recommend (and use with Caesar various antioxidants, Omega 3 fatty acids (fish oils) and various herbs (my favorites being turmeric and astragalus).  Homeopathic remedies can also be very useful for treatment.  Do consult a Holistic Vet or Health Care Practitioner that you trust, for specific suggestions for your own dogs.

Even with “hopeless” cancers, naturopathic medicine can help your fur-baby feel much more comfortable than working without as you can decrease the side-effects of Western medical treatments and/or work without medical treatments to allow your pet as much comfort and healing as possible as you work through the cancer journey together.

Wishing you and your fur-babies the best of health today and always!


Dr. Menen


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