Everyone knows that smoking can cause lung cancer. Even second-hand smoke can cause the disease. But primary lung cancer, when the tumor originates from the lungs, in pets is relatively uncommon. On the other hand, metastatic tumors in the lungs (masses that have spread from a tumor elsewhere in the body) are a more common occurrence in veterinary medicine.
Dr. Alison Book is a veterinary oncology resident at the University of Illinois Veterinary Teaching Hospital in Urbana. She explains that, "primary lung cancer in dogs and cats is rare. As far as percentages go, it accounts for less than one percent of all the types of cancers that occur in pets." A certain type of tumor, a pulmonary adenocarcinoma, is the most common form that occurs in the lungs. Squamous cell carcinomas may also be diagnosed.
Primary lung cancer in dogs and cats is rare
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In recent years, research has shown that second-hand smoke in pets can contribute to lung disease in pets. However, in most cases of a primary lung tumor, the cause remains unknown. Owners may initially notice symptoms such as coughing, lethargy, decreased appetite, or exercise intolerance. Alternatively, these masses may be found incidentally on health screening.
If a veterinarian suspects lung cancer, radiographs (x-rays) are taken. If the tumor is large enough, a white circular mass will be seen on the image. It is very important that three images of the chest be taken when performing radiographs. Owners may wonder why just one image will not suffice for diagnostic purposes; without a right chest view, a left chest view, and a ventral-dorsal view (when the dog lies on its back), a radiologist could miss a tumor that is hidden behind a rib or other dense structure.
Dr. Book mentions that, "one small solitary tumor on radiographs, with no evidence of lymph node enlargement will do better than many larger tumors that have spread." In some cases of primary lung tumors, advanced imaging, such as a CT scan, can be performed to rule out masses elsewhere. If no other masses are found, surgery can be performed to remove the specific lung lobe that is affected. Even with advanced imaging and surgical treatment, the tumors may spread to other organs (sometimes smaller metastatic lesions are too small to be seen with diagnostic imaging).
Although primary lung cancer is uncommon, "there are many types of cancers that have a preferential site of spread to the lungs," mentions Dr. Book. Some of the classic cancers that frequently spread to the lungs are osteosarcomas and mammary tumors.
Experts are not exactly sure why so many cancers spread to the lungs, but there are a couple of theories. One hypothesis is that cells from the tumor that starts elsewhere in the body break off and then lodge in the small capillary bed in the lung vessels. Another theory is similar to a seed in soil--perhaps there is something in the lung tissue that particular tumor cells like, so they are able to grow in that particular environment.
For more information about cancer in pets, contact your local veterinarian.
Source: Alison P. Book, DVM
Author: Ashley Mitek
Maybe it's just a tiny mass on Fido's chest, or a new bump on Fluffy's neck. It may look harmless, but mast cell tumors can look like anything. Even a lipoma, a benign fatty tumor many older dogs get, can easily be misdiagnosed without further testing.
The growth of a mast cell tumor is not a normal, natural process in the body.
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Dr. Alison Book is an oncology resident at the University of Illinois Veterinary Teaching Hospital in Urbana. She says, "mast cell tumors can have a wide range of behavior and prognoses in the dog." They also have varying appearances and can mimic other tumors. Similar to lipomas, they may feel soft and moveable; alternatively they can be firm, red or inflamed lesions. In short, you can't judge a tumor by its cover.
It is for this reason that Dr. Book recommends that your veterinarian aspirate any bump found on your dog that looks suspicious. An aspirate is simple to perform and not very stressful to the patient either. A veterinarian gently sticks a small gauge needle into the mass and fenestrates (small movements) or aspirates (pulls back on the syringe) to pull out cells within the mass. With this aspirate, experts can review the cells under a microscope.
In the case of mast cell tumors, under microscopy you will see, like the name implies, increased numbers of mast cells. These cells normally inhabit certain tissues in the body and are associated with inflammation such as allergic reactions. Release of substances contained within mast cells, such as histamine, are responsible for the red and itchy tissue response. For example, the over-the-counter medication Benadryl is an antihistamine, which helps to counteract the histamine released from mast cells when a stimulus sets them off.
However, the growth of a mast cell tumor is not a normal, natural process in the body. "These tumors occur when the growth and development of a population of mast cells is no longer appropriately regulated by the body," says Dr. Book, "the mass occurs as the result of too many cells accumulating in one location, and in some cases, behaving badly."
The prognosis for a mast cell tumor can vary drastically depending on several factors but correlates most strongly with what the pathologist, a veterinarian specializing in diagnosing disease from body samples, finds. With a biopsy, a small part of the tumor is removed--something which is easily accomplished in many cases with a shot of local anesthetic to numb the area, and then a biopsy punch tool that quickly removes a small portion.
This tissue sample is then sent to an expert who will confirm the patient has a mast cell tumor and assign it a grade from 1-3. "Grade 1 mast cell tumors may be surgically cured with complete removal," notes Dr. Book. And hearing the word "cure" from an oncologist is something to get excited about, considering the worst grade, a 3, is not likely to be cured by the time it is diagnosed. With grade 3 tumors, it can be much more difficult to control both local disease and dissemination to other parts of the body. Treatment for grade 3 mast cell tumors is very dependent on each individual situation, but in some cases you are simply trying to provide a remission and/or palliative care and prolong the animal's life, as well as improve their quality of life.
In the end, what is important to remember is that a mass that looks benign really may not be. If you are lucky enough to catch the tumor sooner rather than later, there is a much better chance your veterinary oncologist will mention the word "cure" in their treatment plan, rather than the much dreaded words, "average survival time," in the prognosis.
If your four-legged friend has a bump, or you have questions regarding tumors in your pet, contact your local veterinarian.
Source: Alison P. Book, DVM
Author: Ashley Mitek
Fellows Fill Huge Need for More Research on Feline Health Issues
Morris Animal Foundation granted Amanda Feline Fellowships to Dr. Jessica Quimby at Colorado State University and Dr. Smitha Pillai at the Ohio State University. Dr. Quimby will study chronic kidney disease therapy and Dr. Pillai will study oral cancer treatment. Each will receive $100,000 for her two-year fellowship.
Despite the cat’s status as America’s No. 1 pet, cats receive less veterinary care and research than dogs.
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First awarded in 2007, these fellowships—fully funded by an anonymous cat lover—honor a beloved cat, Amanda, who died at age 15. The donor knew there was a huge need for more health research to look at feline issues, and she wanted to encourage veterinarians and scientists to pursue this area of study. The fellowships are part of the Foundation’s Happy Healthy Cat Campaign to increase funding for feline health research.
After practicing in a feline-exclusive clinic, Dr. Quimby became frustrated by the lack of information about cat health, so she decided to help cats in another way. Having completed a residency in internal medicine, she is now a PhD student at Colorado State University, focusing her energies on chronic kidney disease, one of the most common diseases in aging cats. She also works in the College of Veterinary Medicine and Biomedical Sciences at Colorado State.
“With this fellowship, I hope to discover why cats develop chronic kidney disease and to develop stem cell therapy for cats suffering from it,” said Dr. Quimby.
Dr. Pillai is currently working as a postdoctoral fellow in feline cancer pathogenesis and treatment at the Ohio State University. She is examining a potential treatment for feline oral squamous cell carcinoma, a common and severely debilitating oral tumor that invades and destroys the jaw bones. She hopes the drug combination she is studying will reduce tumor growth and bone invasion in cats suffering from this painful oral cancer.
“This training experience will enable me to make significant contributions to the biomedical research community, specifically to animal patients suffering from invasive bone cancer,” Dr. Pillai said.
Despite the cat’s status as America’s No. 1 pet—there are more than 82 million in U.S. homes—cats receive less veterinary care and research than dogs, and too few scientists are studying feline health issues. Morris Animal Foundation launched the Happy Healthy Cat Campaign in 2008 to raise pet-owner awareness of feline health issues and to increase funding for feline health research and scientist training.
For more information or to support the Happy Healthy Cat Campaign, visit www.research4cats.org. Keep up to date with Morris Animal Foundation on Facebook at “Morris Animal Foundation” and Twitter at “Morris_Animal.”
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