THE DIAGNOSIS EVERYONE IS AFRAID OF,

BUT EVERYONE SHOULD BE TALKING ABOUT

Cancer. It is a word no one wants to hear, but a diagnosis that is made all too often for our pets. The good news is that cancer is still less common than other long term illnesses like heart disease, kidney disease or endocrine disease. The bad news is that while there have been advances in treating cancer, those advances haven't been as successful or economically feasible as those made in the treatment of the other long term diseases. While the incidence of cancer probably hasn't increased over the years, our ability to diagnose it sooner and more effectively has. The good thing about that is, with some cancers, a quick diagnosis can mean a positive outcome for your pet.

Cancers come in 3 classes, a kind of good, bad and ugly situation. Good cancers don't spread, are easily removed, or sometimes, even resolve on their own. They are often incidental findings during a regular check up, that may lead to some anxiety, but with proper treatment, do not affect duration or quality of life. Bad cancers are difficult to remove and do spread to other tissues.  However they are usually very slow to grow and slower to spread, so they often can be managed.  Bad cancers are usually diagnosed because the caretaker notices a growing lump, or some sort of discomfort in their pet.  Signs of illness or pain may take months to a couple of years to begin to threaten  a pet's quality of life, so your veterinarian may be able to extend that time with medications, or, depending on the location, surgery to make tumors smaller.  Ugly cancers are fast growers, quick to spread, and usually cause immediate illness. More often than not, ugly cancers are causing severe enough illness that quality of life is an issue at presentation and deteriorates rapidly after diagnosis.  In these cases, your veterinarian may only be able to recommend hospice care, or euthanasia.

Good cancers are those that we can cure simply by removing them. Thankfully, many cancers fall into this category. Every dog owner probably knows about “fatty tumors” or Lipomas. If you have a bully breed or boxer, your puppy may have had a Histiocytoma as a teenager. Histiocytomas and Lipomas are cancers. They are considered benign because they don't cause illness, they don't spread to other tissues, and they don't recur if they are excised. Many skin cancers and a few abdominal cancers fall into this category. While surgery and anesthesia are still necessary, the good chance of a curative outcome make the risk of anesthesia and the cost of the surgery worth while.

Bad cancers, are the kind that can be treated or controlled, but may recur or get worse later in life. Mast Cell tumors and Nerve Sheath Tumors form lumps on or under the skin that can be removed, but because of the type of tissue they originate from, they tend to adhere to surrounding tissues, making it very difficult for them to be completely eradicated. Bone and cartilage tumors affect joints and long bones and while some can be cured with surgery, often the surgeries are very invasive, with an increased risk of bad complications. These types of cancers are typical in young and middle aged dogs and cats, and are are often considered to have inherited traits since certain types are more commonly found in certain breeds.

Cancers in this category have the potential to make animals sick or painful, but are slow to grow, and IF they spread to lungs or liver, usually take years to do so, making them manageable but not curable. The decision to surgically excise them must be made based on the long term outlook, the acceptance of surgical complications either during surgery or immediately afterward, the potential need for post-operative nursing care depending on the pervasiveness of the procedure, and the costs for such complicated procedures. Sometimes the long term prognosis of these cancers can be improved with chemotherapy or radiation therapy, but the caretaker must be committed to the nursing care that will be needed, the travel involved in weekly visits for therapy, and the costs involved with more advanced treatment. The pet must also like their vet, as weekly treatments for radiation and or chemotherapy are not ideal for fearful or aggressive patients.

Ugly cancers are the type that grow fast, spread to multiple areas, and cause your pet to act ill. These cancers are difficult to treat surgically, as they have often spread at the time of diagnosis, and are traditionally resistant to chemotherapy or radiation treatments. Liver cancers, pancreatic cancers, and oral cancers, all are fast to grow and quick to lessen your pet's quality of life. Most times these types of cancers are found in older patients and are probably more related to lifestyle and environment than hereditary factors. Unfortunately, the pet is often so sick at the time of diagnosis that the only treatment option is euthanasia, though hospice care can sometimes provide enough comfort for a patient to allow a family time to say good bye.

The five most common cancers seen in the dogs are Lymphoma, Mast Cell Tumors, Hemangiosarcoma, Osteosarcoma, Carcinoma. In cats it is Lymphoma, Carcinoma, and Digit Cancer.

Lymphoma is a cancer of the tissues that make white blood cells. These tissues are found in the bone marrow, intestinal tract, lymph nodes, and in the thymus gland in the chest cavity. It is considered bad cancer, as it is treatable, but not curable, and the treatment involves chemotherapy. It is common in all cats, and often associated with the virus that causes Feline Leukemia. In dogs, there is a strong feeling that it has inherited traits, as it is seen predominantly in Retrievers and Boxers. It is usually a cancer of young or middle aged pets. Some forms of Lymphoma are very responsive to chemotherapy, and animals can live up to 18 months after treatment, or two years after diagnosis. Others are more resistant to treatment, and pet's can become deathly ill within months of their diagnosis. Without any form of medical treatment, most forms of Lymphoma will degrade quality of life within 2 months of the diagnosis.

In cats, Lymphoma tends to start either in the Thymus or the GI tract. Cats will present either with trouble breathing because they have fluid in their lungs, or with a decreased appetite and weight loss because the cancer in the intestines is making them nauseous. Most dogs with Lymphoma are brought in because owners feel enlarged lymph nodes in their dog's neck. Lymphoma is considered to have the same long term prognosis as heart disease or kidney disease, but that is only if the pet's caretaker can afford the chemotherapy, and the patient can tolerate the side effects and the frequent vet visits.

Mast Cell Tumors are skin cancers that are very common in short haired dogs, especially Pit Bulls, Bull Dogs, and Boxers. They are usually easily diagnosed during a physical exam. They look like round, often hairless lumps, usually on the legs or chest. Your veterinarian would take an aspirate of the lump and look at it under the microscope to see the cells that would be suggestive of a MCT. They come in four grades. Grade 1 being the best and easiest to treat, and Grade 4 being the most likely to cause a shortened life span. Grade 1 and 2 MCT are considered good cancers, with the potential to be cured with surgical removal. Catching them small is key. They have a tendency to come back if even microscopic pieces of the tumor are left behind. If your veterinarian is suspicious of a MCT, you should plan on removing it and then having a biopsy performed to make sure he or she got it all. Grade 3 and 4 MCT have a higher tendency to recur and spread, so they are bad cancers. Many will not be able to be completely removed and require some form of medical care to keep your pet comfortable. If removable, post-operative radiation or chemotherapy treatments do seem to help the long term outcome of these cancers. The long term prognosis for a completely removed Grade 1 or 2 MCT is 5 years. For a Grade 3 or 4, it depends on whether or not the tumor recurs. If it can't be excised because of its location, dogs can become ill from this cancer within months of diagnosis.

Hemangiosarcomas are cancers that arise from tissues that make red blood cells. They are also typical for young to middle aged dogs, and there are certain breeds that are more prone than others, so genetics does play a factor. However, all medium sized dogs are prone to this cancer. These cancers are very invasive, but slow spreaders, making them bad cancers. Most commonly it causes tumors to develop in the spleen or on the heart. Splenic tumors will grow until they begin to bleed. Tumors on the heart will grow until they interfere with the heart's ability to pump blood. In both cases, dogs will present suddenly pale and weak. They will be unable to stand, and may have difficulty breathing because of poor oxygen delivery. If the mass is in their spleen, and they haven't bled too much, removal of the spleen can prevent further bleeds and drastically improve quality of life, but within 6 – 12 months, the cancer will show up in the liver or lungs. If the mass is on their heart, the dog may respond to medications that help regulate heart function, but eventually heart failure will occur. Chemotherapy and radiation have not been shown to help these dogs.

Osteosarcomas are bone cancers. Bone and cartilaginous cancers are usually slow growers and slow to spread, but impossible to cure, putting them in the bad category. They have strong genetic predispositions, with Rotties, Shepherds, Retrievers, and Giant Breeds being very prone to developing these cancers before the age of 7. Osteosarcomas develop in all bones, but are more commonly diagnosed in the limbs. Those dogs, and occasionally cats, that have lesions in their limbs, present with lameness and pain. They can be treated, but treatment usually involves amputation of the affected limb. While 3 legged animals do amazingly well to adjusting to their new means of getting around, bone cancers do tend to spread to the lungs. Chemotherapy can make it take longer for the spread to occur, but at best, we hope for providing an extra 18 months of good quality life. Without surgery, your veterinarian can provide far more pain management than was available even 5 years ago, but there is a risk that the cancer can weaken the bone enough to cause pathologic fractures.

Carcinomas are cancers that affect glandular tissue. They are fast growers, quick to spread, and rapidly cause illness. They are the classic, ugly cancer. In cats, they typically show up in the mouth or mammary tissue. In dogs, they develop in the bladder, anal glands, mammary glands, pancreatic gland, liver, and intestinal tract. Mammary gland cancer in dogs is preventable by having your dog spay before her first heat. In cats, this does not seem to help. There is a feeling that chronic inflammation can predispose to these cancers, which means chronic urinary tract infections, anal gland infections, mouth infections, or heats, could be part of what triggers bladder cancer, anal gland cancer, oral cancer, and mammary cancer. If this is the case, good preventative medicine can help lessen the risk of your pet developing Carcinoma. Some of these tumors can be managed with surgery, but cures are not the goal, and in some instances, the cancer will recur at the surgery site faster than if left alone. Most of the time, your veterinarian will just try to manage whatever pain or discomfort your pet is in, until the time is right to say good bye.

Cats tend to get a lot of cancer in their feet. Swollen, painful toes are associated with toe nail tumors that can either be Carcinomas (glandular origin) or Sarcomas(tendon or muscle origin). The good news for this particular variety of cancer, is that surgery can often be curative, making them good cancers. While they are tumors that may spread to lungs, most are quickly identified because of their visibility and the amount of pain that they cause. If they are caught early, amputation of just the affected toe can prevent spread, and lead to a long and happy life for your cat. However, a chest radiograph should always be done first, as in some cats, toe tumors are actually a primary lung cancer that has spread to the foot.

While it is never good to hear that your pet has cancer, it is important to remember that SOME cancers can be treated and managed with a reasonable hope for a good and long quality of life. The chances of a good outcome GREATLY improve with early diagnosis and appropriate treatment. Don't put off getting the lump checked because you assume there is nothing that can be done. I found a tiny little lump on my Pittie in 1997 that I almost ignored because it was so small I, a vet, didn't think it was of concern. I ended up removing it as an afterthought when I had her teeth cleaned. It came back as a Grade 3 Mast Cell tumor. Because of where it was, her breed, and the grade, I was originally told to expect her to become ill from it spreading elsewhere within 2-3 years. Siri went on to live another 8 years, going camping, canoeing, playing frisbee, and swimming in the pool right up until the week before she died. She had a total of 3 recurrences during those eight years. Each required surgery that she bounced back from within a week, though she never was very good about leaving her sutures alone. In the end, the cancer must have spread to her spleen. I lost her suddenly one day in 2005.

The key to successful treatment for any disease, or injury, is early intervention. We are all afraid we might hear bad news when there is something wrong with our pets. But not taking your pet to the veterinarian because you are afraid of what you might hear, is one way to guarantee that you've waited too long to have hope for a good outcome. With all disease, early diagnosis and treatment is the key. Lipomas are completely benign, unless you let them grow so large that they become impossible to remove. Mast Cell tumors can be life threatening, but if you remove the lump when it is less than the size of a quarter, it can likely be cured with a half day in the hospital, a mild sedative, and some local anesthetic. You won't know what your options are, until you diagnose the problem, and quite often, what we imagine is worse than than the reality. When it is not, the sooner you get your pet to the veterinarian, the more likely there will be a cost effective way to do something that will truly help save your pet's quality of life.

For those times when the reality is worse than what we imagine, it is important to remember that every pet deserves the best life you can give him or her, and the most humane and dignified passing you can give them. By talking to your veterinarian about all of the potential treatment or hospice options that are available, you can make the most responsible decision for your pet and your family, knowing you gave them the best life possible, and the most comfortable ending to that life once that time has come.



More Information

For more information on common cancers in dogs and cats:

Canine Lymphoma

Feline Lymphoma

Bone cancer in dogs

Mammary Cancer in dogs

Mammary Cancer in cats

Oral Carcinoma in cats

Lipomas

Mast Cell Tumor

Histiocytoma

Hemangiosarcoma

For Information about Cancer awareness, or to donate to Veterinary Cancer research:

We are the Cure

RI Chapter of We Are the Cure

Cancer Awareness for Dogs

The Pet Cancer Center



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