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 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.
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
Compared 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.
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.
From 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.
We all rely on numbers to help us make decisions. The stock market is above 16,000; time to sell. Your chance of winning the Powerball Jackpot with a two dollar ticket is one in 175 million, but it’s only two dollars so you buy yet another losing ticket. One in four Americans dies of heart disease every year; more exercise and less butter for you. In my line of work, veterinary medicine, quoting numbers is not nearly as easy.
I have been struggling with a particularly complicated cancer case the past few weeks. After hours of discussion and many more of pondering the options, a clear plan has emerged for this patient. And then the client asked the number one question: “What are the chances my pet will benefit from this procedure?” Having never been much of a math whiz or very successful at gambling, explaining the concept of odds is difficult. The odds of A versus B are calculated from a large group of patients with the same disease. But when I am talking about Fluffy or Fido, it becomes harder to predict the outcome for an individual patient. In some ways it’s a 50-50 coin toss. Your pet gets better or it doesn’t. Because medicine rarely has 100% certainty, no doctor, human or animal, will ever guarantee a 100% chance of success. Even with a 99.9% chance of success, there will be some patients who do not have the desired outcome after the test, treatment or surgery is completed.
An article in last week’s New York Times ‘Science Section’ written by a physician, numbers and their connection to disease appear again. Dr. Abigail Zuger writes about using a reasoned numerical approach (“30 percent of people with your problem of X will develop Y”). Yet, she writes, “many studies (and all casinos and lotteries) illustrate how abysmal is the average person’s understanding of risk when couched in mathematical terms.” Her patients have a hard time grasping the importance of risk factors on their future health or as she calls them “pre-diseases.”
If two medical professionals have difficulty using numbers in their daily practice, then how can people or pet owners make well-informed decisions on healthcare matters?
- Preventing disease is much easier (and cheaper) than correcting a problem. If your veterinarian gives you numbers on preventing disease, pay close attention. For example, obesity quadruples your dog’s risk of cruciate ligament rupture. Getting your dog’s weight down saves money two ways – you buy less food and your dog doesn’t need an expensive reconstructive knee surgery.
- There are actually some medical conditions that doctors can predict the outcome with reasonable certainty; for example, diabetes. Without administration of insulin, which is deficient in dogs and cats with diabetes, your pet will die of high blood sugar within days.
- Since not all diseases come with certainty of outcome like diabetes, think about quality of life. If your pet’s current problem is decreasing their quality of life, consider a treatment to improve it. Keep in mind this is where numbers can become overwhelming and sometimes a decision is made based on your heart rather than your head.
Tracy and her 14 year old grey tabby, Baller, have experienced a few bumps in the road this past year. In April, Tracy noticed Baller, named after a rap song, was defecating outside his litter box. He also had diarrhea, but he didn’t seem very sick since he was eating well and was his usual playful self. Her neighborhood veterinarian examined Baller and found two pounds of weight loss. Tracy thought she could breathe easier when she heard the blood tests were normal, but an abdominal ultrasound revealed Baller had colon cancer.
Minimally Invasive Testing
Tracy brought Baller to The Animal Medical Center for a consultation with one of our board certified oncologists. Baller’s oncologist, Dr. Maria Camps, explained the most common type of cancer in cats is lymphoma, and recommended a minimally invasive approach to diagnosis since lymphoma is treated with chemotherapy, not surgery. Ultrasonography was used to direct a small needle into the colon tumor and retrieve cells from the tumor. Within hours, Tracy found out she and Baller were facing an uphill battle against lymphoma. The anticipated survival time for a cat with lymphoma treated with chemotherapy is less than one year.
Dr. Camps actually gave Tracy so much hope, and Dr. Mollica, Baller’s regular veterinarian and a former AMC intern, was also very supportive. These two veterinarians really gave Tracy that extra oomph she needed to continue Baller’s treatment. Ms. Koch says, “I knew the chemo was working almost immediately. Right after his first treatment he was feeling better again. He is one to make it known when he has issues by hiding under the bed, not eating and not able to use the bathroom. But, it was amazing that right after his first treatment he was back to his normal routine. I thought it [the chemotherapy] would help a bit, but I didn’t realize how much better it would make him feel. He was like a whole new cat, which makes me sad because who knows how long he was feeling bad before he really started to show it.”
About one third of the way through his prescribed course of chemotherapy, and just when Baller’s cancer seemed to be in control, a roadblock obstructed the path to further cancer treatments; Tracy was laid off.
Buddy Fund Helps Out
This is where the Buddy Fund comes in to assist Tracy and Baller. The Buddy Fund, one of AMC’s Community Funds, was established to provide financial support for AMC patients with cancer whose owners could otherwise not afford to treat their four-footed family members. The name of the Buddy Fund has a double meaning. The original donors to the fund had a very special cat named Buddy and the fund acts as a “buddy” to owners of pets with cancer. Baller’s oncologist recommended him for the fund because he was responding exceptionally well to the prescribed course of chemotherapy. Discontinuation of treatment would put him at high risk for relapse of his cancer.
Thanks to the Buddy Fund and its generous supporters, Baller completed his chemotherapy protocol just before Thanksgiving and without missing a single treatment. At his most recent follow up appointment he was given a thumbs up because no tumors were detected during the examination. Going forward, Baller will continue to be monitored for tumor recurrence. As the one year anniversary of his diagnosis approaches, everyone has their fingers crossed for Baller. Tracy looks forward to a time when she is employed again and can be a “buddy” to another deserving cat through a contribution to AMC’s Buddy Fund.