National Pet Cancer Awareness Month: Pet Cancer Treatment Options, Part II

November 12, 2014

dog receiving chemotherapyNovember has been designated National Pet Cancer Awareness Month to raise awareness about the causes, prevention and treatment of dogs and cats with this terrible disease. To raise awareness of the possible treatments for pet cancer, this second part of my two-part blog on cancer treatments for pets discusses three additional treatment therapies: chemotherapy, immunotherapy and targeted therapy. Part I focused on surgery and radiation therapy.

Chemotherapy
Although the use of radiation therapy in humans preceded the use of chemotherapy, chemotherapy was more widely used in pet cancers before radiation therapy. Chemotherapy is administered when a biopsy indicates a tumor has spread or might spread, such as in feline breast cancer.

Chemotherapy can also be administered when a tumor is too widespread for either surgical removal or radiation therapy. At the top of the veterinary list of pet cancers treated with chemotherapy is lymphoma.

Veterinary oncologists treat both dogs and cats for lymphoma using a variety of chemotherapy drugs. Most commonly used is the CHOP protocol. CHOP is an acronym representing the first letter of each chemotherapy drug in the protocol and is repurposed from human oncology. Despite the bad reputation chemotherapy has, both cat and dog owners report a good quality of life in their pets receiving chemotherapy.

Immunotherapy
The concept of harnessing the cancer patient’s own immune system to fight cancer is an idea that has been around a long while. The idea came to fruition when a vaccine to treat melanoma in dogs was approved in 2010.

Dogs suffering from melanoma are given four vaccinations over two months and then boostered every six months. This treatment protocol prolonged survival by 300 days or more in dogs receiving the vaccine. In people with lymphoma, treatment using monoclonal antibodies like Rituxan® has dramatically improved patients’ survival time. In a similar vein, AMC oncologists are currently studying a monoclonal antibody against T cell lymphoma and a monoclonal antibody against B cell lymphoma is also available.

On the horizon for the treatment of lymphoma is a new cancer vaccine for a particular type of lymphoma in dogs called large B cell lymphoma.

Targeted Therapy
In 2009, toceranib phosphate, known as Palladia®, became the first targeted therapy approved for use in dogs diagnosed with mast cell tumors.

A second targeted therapy, mastitinib, known as Kinavet®, has conditional approval for the treatment of the same tumor. Targeted therapies exploit a physiologic abnormality in tumor cells, not present in normal cells. Targeted therapies commonly work by turning on or off a cellular process critical to cancer growth and metastasis, halting tumor growth. In the future, expect to see more targeted drugs used in dogs and cats.

Because cancer is diagnosed in over six million pets each year, you may be faced with this diagnosis in your favorite furry friend. But treatment of cancer in pets is possible. You and your pet have more treatment options and more specially trained veterinarians than ever before to help you achieve a good outcome if your pet is diagnosed with cancer. To find a board certified veterinary cancer specialist in your area, visit the American College of Veterinary Internal Medicine website and use their search function.


National Pet Cancer Awareness Month: Pet Cancer Treatment Options, Part I

November 5, 2014

National Pet Cancer Awareness MonthNovember has been designated National Pet Cancer Awareness Month to raise awareness about the causes, prevention and treatment of dogs and cats with this terrible disease. According to the Morris Animal Foundation, there are six million new pet cancer diagnoses every year. That number of diagnoses translates to millions of pet cancer treatments each year. Traditionally, surgery, chemotherapy and radiation therapy were considered the mainstays of cancer treatment in both people and pets, but recent innovations add immunotherapy and targeted drug therapy to the growing list of cancer treatments for pets.

To raise awareness of the possible treatments for pet cancer, Fur the Love of Pets will feature this two-part blog on cancer treatment options in pets.

Surgery
Surgical removal as a treatment for cancer has been practiced since Roman times. Perhaps because of a lack of surgical skill, coupled with a lack of techniques for general anesthesia, surgery was not particularly effective, if we believe the Roman physician Celsus. He wrote, “After excision, even when a scar has formed, none the less the disease has returned.” Today we know much more about how to treat canine and feline cancer patients with surgery. Tumors such as canine breast cancer, soft tissue sarcomas and mast cell tumors are potentially cured by surgical excision alone. The key to treating many types of tumors with surgery is to remove a wide swath of normal skin and tissue around the tumor to ensure complete removal of the cancer-causing cells. Anyone with a pet treated with surgery for mast cell tumor or soft tissue sarcoma can attest to the fact that the actual incision was much bigger than they anticipated. Current guidelines recommend as much as 3cm (1.25 inches) of normal tissue be removed on all sides of the tumor as part of a cancer surgery.

Surgical treatment of pet cancer recently became highly specialized when the American College of Veterinary Surgeons (ACVS) recognized the Veterinary Society of Surgical Oncologists (VSSO). Members of VSSO have achieved a high level of competence in cancer surgery though their participation in a surgical oncology fellowship following certification by ACVS.

Radiation Therapy
The second cancer treatment to be widely used in humans was radiation therapy. Veterinarians began using radiation therapy in pets in the early 1980s. Board certified veterinary radiation oncologists treat a wide variety of tumors including brain tumors, thyroid tumors and melanoma.

The radiation therapy equipment The AMC currently uses is our third machine since 1989. The first two used cobalt as the radiation source. Now we have a linear accelerator with electron beam capabilities, image modulated radiation therapy and stereotactic radiosurgery – a huge advancement in technology from our first rudimentary cobalt machine. To ensure exact positioning for each treatment, a customized “bed” is created for each patient. View a video of one of our vacuum assisted positioning devices being used in a feline patient.

Want to learn how to recognize signs of cancer in your pet? View our slide show on the “Ten Warning Signs of Cancer in Pets.”

In Part II of this blog, I’ll discuss chemotherapy, immunotherapy and targeted therapy.


What Does a Vet Tech Do?

October 8, 2014

July is Sarcoma Awareness Month

July 23, 2014
The wrist of a dog diagnosed with osteosarcoma.

The wrist of a dog diagnosed with osteosarcoma.

Both veterinary and human oncologists talk about three big families of cancer: carcinomas, sarcomas and tumors of the blood and lymphatic system. Carcinomas frequently originate from glands – like breast or prostate carcinomas. The most well-known tumors of the blood and immune system are leukemia and lymphoma. Sarcoma is a form of cancer arising from bones, tendons, muscles, nerves, joints, blood vessels and fat. Over 13,000 Americans were diagnosed with sarcoma in 2013. Sarcomas are rare in adults, but represent 15% of all childhood cancers.

Pets Get Sarcomas Too
Cancer registries for pets exist, but recording the types of cancer pets have is not mandatory as it is for human cancer diagnoses. Some information about the occurrence of sarcomas in pets has been published. In a survey of Greek dogs with skin cancer, 40% of the tumors were sarcomas, the two most common were mast cell tumors and fibrosarcoma. A study of American dogs found the mast cell tumor was the most common malignant tumor on this side of the Atlantic as well. An Italian tumor registry based out of Genoa found sarcomas occurred more commonly as a dog aged. Breed also influences the development of sarcomas. A survey of flat coated retrievers in the United Kingdom found 55% of malignant tumors and 26% of all tumors in this breed were sarcomas.

Common Dog Tumors with the Last Name Sarcoma
Osteosarcoma (bone sarcoma) is ten times more common in dogs than in humans. Large and giant breed dogs have a greater risk of developing osteosarcoma. In dogs, the tumor destroys the bone (see the above photograph) and to control pain, amputation is often recommended; although limb-sparing surgery and radiation therapy are also used to control pain. Coupling surgery or radiation with systemic chemotherapy helps to control the spread of osteosarcoma and thus prolongs survival.

Hemangiosarcoma is a tumor of blood vessels. Because the vessels are cancerous, they rupture easily and dogs with hemangiosarcoma frequently end up in the animal ER with catastrophic hemorrhage from a ruptured tumor in their spleen, liver or heart.

Soft tissue sarcomas include tumors whose name is a mouthful like hemangiopericytoma, or that sound like a more benign tumor, such as the nerve sheath tumor. Soft tissue sarcomas are a mixed group of tumors frequently of the skin and often lumped together because of a similar clinical course. These tumors send tentacles of tumor out into the surrounding tissue, making complete removal challenging. Successful surgical removal of a soft tissue sarcoma requires a much bigger incision than most dog owners expect in order to remove the tentacles. If residual tumor is left behind, these tumors commonly recur and may require radiation therapy to control.

Cat Tumors with the Same Last Name

An injection site sarcoma in a cat just prior to surgical removal.

An injection site sarcoma in a cat just prior to surgical removal.

An injection site sarcoma is a very specific type of sarcoma, most commonly found in cats where injections are administered, such as a vaccination or insulin injection. When these tumors develop on the nape of the neck (as in the photograph on the right) or on the hip, they are very difficult to completely remove and they recur much more frequently than soft tissue sarcomas of dogs. Most patients need follow up with radiation therapy, and because 25-40% of these tumors metastasize, chemotherapy as well.

Raising Sarcoma Awareness

  • Osteosarcoma causes bone pain and limping. Don’t assume your limping dog has a bum knee or weak ankles. Have your limping pet seen by your veterinarian.
  • Soft tissue sarcomas and injection site sarcomas often start as a skin lump. See your veterinarian for any lump that is enlarging over a month, is larger than 2 cm (3/4 inch) in diameter, or has been present for more than 3 months.
  • Sarcomas can often be diagnosed based on a fine needle aspirate. Help your veterinarian take the best care possible of your pet and allow this simple procedure if it is recommended.

10 Warning Signs of Cancer in Pets

May 21, 2014

How Do Dogs’ Noses Work?

April 30, 2014
dog nose

Photo: Mark Watson

Dog noses have been in the news lately. Not just because dogs can sniff out a cracker crumb between the sofa cushions or because dogs smell the new bag of bacon strips through the closed pantry door, but because dog noses are being put to work in a very serious way.

For hundreds of years, dogs, like the Bloodhound, have been employed as search and rescue workers to find missing people after being given a whiff of the missing person’s clothing. Now medical sniffer dogs are being trained to diagnose cancer, detect low blood sugar and predict an epileptic seizure. Several features of dogs’ noses make their sense of smell better than our own.

Bigger is Better
CT scan of a dog's noseCompared to the size of their face, dogs have big noses – well most of them do. And, a bigger nose means they have more area for smell receptors. Inside the nasal passages, the dog has ruffles of tissue called turbinates which increase the surface area that accommodates their smell receptors. Compared to our 5 million, dogs have 300 million receptors on their nasal turbinates. The CT scan on the right shows the ruffles of tissue inside a dog’s nasal passages, and if you watch our video, you can see what turbinates actually look like when a rhinoscopy (nasal endoscopy) is performed.

Bidirectional Smelling
Take a look at your dog’s nose. Notice the nostrils have slits on the sides and the openings are a bit more to the side than directly out front. These features give your dog’s sense of smell directionality. New smells come in from the front and old smells go out through the side slits with exhalation, allowing new smells to constantly bathe the smell receptors.

More Brain Power
Because dogs’ sense of smell is their most highly developed sense, they devote an enormous amount of brain power to the act of smelling. Compared to our rudimentary sense of smell, there is 40 times more canine brain power dedicated to smelling, which allows dogs to differentiate 30,000 to 100,000 different smells. Our repertoire of smells is only 4,000 to 10,000 different smells.

For more about these scent-sitive dogs, watch my interview on Fox5 News with Liz Dahlem.


Dogs Get Cirrhosis? Cats Get Lung Cancer?

April 9, 2014

cat and dogFrom a medical perspective, we are not that different from our pets. Humans, dogs and cats have many diseases in common and the treatments for these diseases are often strikingly similar. Diabetes in pets is treated with a special diet and insulin injections; radioactive iodine therapy is used to treat feline hyperthyroidism; and dogs with heart disease receive diuretics (water pills) and ACE inhibitors. Despite these similarities, disease in our pets is not always the same as it is in humans.

Dogs Get Cirrhosis?
In people, cirrhosis of the liver is most often associated with alcoholism, or hepatitis virus infection. Since dogs don’t drink (or they shouldn’t) and the hepatitis virus is a human virus which does not infect dogs, how do dogs get cirrhosis? The diagnosis of cirrhosis does not imply a cause and the cause in dogs differs from humans. Cirrhosis is a liver disorder in which the liver loses its normal structure and function as a result of chronic inflammation. Inflammation, in turn, causes replacement of normal liver cells with scar tissue and destroying their function. If enough of the liver is damaged, dogs show signs of liver failure: jaundice, accumulation of abdominal fluid (ascites) and a bleeding tendency. Labrador Retrievers, Cocker Spaniels and West Highland White Terriers are breeds with an increased risk for developing liver inflammation and cirrhosis. The inciting cause of the inflammation in dogs remains a mystery.

Lung Cancer in Nonsmokers?
The number one cause of lung cancer in humans is cigarette smoking. Since pets don’t smoke, why do they get lung cancer? Veterinarians don’t know exactly. Studies evaluating the impact of the home environment on dogs with lung cancer did not find an association with either living in an urban or a rural environment. We know secondhand smoke affects pets, increasing their risk of lymphoma and oral squamous cell carcinoma, but secondhand smoke has not yet been linked to lung cancer in dogs and cats. If you smoke, don’t do so near your pet; better yet, quit.

But What About Heart Attacks?
Heart attacks, a leading cause of sudden death in the United States, occur when the blood flow to the heart is abruptly blocked. Most heart attacks are the result of high cholesterol and blockage of the coronary arteries which supply blood to the heart muscle. Dogs and cats do not develop coronary artery disease as a result of high cholesterol, and thus do not have heart attacks like their human companions. However, since heart attacks often cause sudden death, grieving families frequently blame a heart attack when their pet dies unexpectedly. Heart disease in pets can be a cause of sudden death due to abnormal heart rhythms, ruptured heart valves and bleeding tumors of the heart.

To read more on disease affecting pets and people, read some of our previous blog posts.


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