Cancer can strike every organ in the body, and each different type of cancer carries a different prognosis and requires a different treatment. That’s because, although we tend to lump all cancers into the same basket, each one is a separate disease. That is true when we look at cancers within the same species (such as all human cancers or all canine or feline cancers) or when we start comparing the same kind of cancer across species (such as skin cancer in humans and canines). In this article, we take a brief look at how cancers that are important in people usually manifest differently in our pets.
According to the National Cancer Institute (NCI), a group that tracks cancer diagnoses and outcomes among humans, the top five cancers in people are breast cancer in women; prostate cancer in men; and then lung, colorectal and skin cancer in both genders. That probably doesn’t surprise you, since your doctor is likely always talking to you about various screening tests, such as the mammogram or colonoscopy, or about the risks of cigarette smoking or not wearing sunscreen. Organizations like the NCI record and publish information about human cancer rates in the United States to help assess the impact of new treatments and prevention strategies.
There is no national organization that tallies the occurrence of cancer in pets like the NCI does for humans, but veterinarians know that the top cancers you should worry about in your pet are very different from those you should worry about for yourself. You won’t hear me recommending, for example, a screening colonoscopy for your Curly-Coated Retriever or a PSA (prostate specific antigen) test for your Persian. That’s because colorectal and prostate cancers are very uncommon in pets. Since pets don’t smoke, lung cancer is also uncommon. But there are other cancers that are common in both pets and people. Let’s take a look at the top four among those that we veterinary oncologists worry about.
Just as in women, breast (mammary gland) cancer is a commonly diagnosed cancer in dogs and cats — if you live in a region where spaying and neutering is not part of a routine pet preventive health care program. Removal of a dog’s ovaries before her first heat cycle during a spay procedure dramatically decreases the occurrence of breast cancer. That is why one common recommendation from veterinarians is to spay your puppy at about 6 months. Spaying also reduces the occurrence of breast cancer in cats. Breast cancer is the most common tumor found in female dogs and the third most common cancer in cats. In humans, it is one of the top three cancers in women, but obviously, preventive measures differ. In humans, we normally use screening mammograms as an early detection tool.
In cats, one in three cancer diagnoses is lymphoma, a cancer of a portion of the immune system known as the lymph system. It is most often diagnosed in the feline gastrointestinal tract, but any organ can develop the cancer. Dogs, too, can develop lymphoma. For example, both of former President George W. Bush’s Scottish Terriers, Barney and Miss Beazley, died from the malignancy.
Despite the incurable nature of lymphoma in cats and dogs, chemotherapy is the mainstay of treatment. Chemotherapy can offer pets who are suffering from the disease an improved quality and quantity of life. The typical dog receiving chemotherapy for lymphoma lives an extra year, which is a long time in dog years. In comparison, some forms of human lymphoma are curable, while others are not.
Although skin cancer is common in both pets and people, how it manifests as a disease is different. I rarely see skin cancer in pets caused by overexposure to the sun. The most common skin cancer I see in my daily oncology practice is mast cell tumor (MCT), mostly in dogs and occasionally in cats. Physician oncologists, however, rarely see that tumor in their practices. Most humans have never heard of a mast cell, but nearly all of us have felt their negative effects, since those are the cells responsible for allergic reactions ranging from from those to bee stings to hay fever. A mast cell tumor in pets occurs in the skin or just below the skin and is one of the tumors pet owners can identify just by petting their animals.
Mast cell tumors may just be a bump in the skin that looks like any other benign fatty tumor, but more commonly they are pink to red and may be scabby. A simple in-office test known as a fine needle aspirate can help in the early identification of an MCT. A veterinary pathologist will evaluate the aspirate and, if necessary, recommend surgical removal of any mast cell tumor. Surgery is often all that is needed to cure your dog of the tumor, but in some severe forms, chemotherapy and radiation therapy are also needed to control the malignancy.
Melanoma can be a concern in pets, but it is rare compared to its occurrence in people. Unlike the skin spots that alert human patients and physicians to its presence, melanoma in dogs is usually found in the mouth or nail bed. In cats, the most frequent location is in the iris, the colored part of the eye.
Osteosarcoma, or bone cancer, is a disease in pets that shares some similarities to the disease in people. Osteosarcoma in dogs serves as a model for the disease in children due to its similar behavior in both species. It is diagnosed more commonly in dogs than in children, and the good news is that research to improve treatments for dogs with the disease has been translated into new and better treatments for children, showing yet again how our enduring friendship with dogs is beneficial.
For example, ongoing investigation into naturally occurring canine osteosarcoma in dog patients has allowed for the testing of surgical methods that are readily translated to pediatric osteosarcoma — something that can’t be done with rodent models of the disease. The most notable contribution of dogs to the treatment of human osteosarcoma is the pioneering of limb-sparing surgery to remove tumors without removing entire limbs. The NCI has funded that groundbreaking research.
Next on the horizon for osteosarcoma is the investigation of genetic abnormalities leading to the disease and the development of molecularly targeted therapies against those abnormalities.
In dogs, an early sign of osteosarcoma is limping due to pain resulting from the destruction of the bone by the tumor. Although difficult to discuss with fear-fraught pet families, amputation of the leg can dramatically improve quality of life for dogs afflicted by the disease.
Chemotherapy slows the spread of osteosarcoma, and lucky dogs may experience a year or more of good quality of life.
Though we can see that cancers in pets and people differ in many ways, basic common sense when it comes to prevention and early detection in both species is the same. If you, the diligent pet owner, are concerned about your pet’s cancer risk, see your veterinarian for a complete examination and a conversation about minimizing risks. For more on detecting cancer in your best friend, review the Ten Warning Signs of Cancer in Pets.
Fleas and ticks are more than just an annoyance to pets — and to pet owners, who have to listen to the scratching or remove the ticks. These unwanted critters are a potentially significant source of disease, misery and expense.
As the weather warms up, flea and tick season kicks into high gear. And that’s when claims at Veterinary Pet Insurance (VPI) for health problems related to these pests pick up, too.
As chief veterinary officer for VPI, I have both professional and personal experience with fleas. VPI’s offices are in Southern California, one of those places where the external parasites that plague pets never feel the effect of snowstorms and freezing temperatures on their life cycles. But even in parts of the country that experience a deep freeze in the winter months, fleas and ticks are a perennial problem.
When we discuss fleas and ticks, we’re not talking about just two kinds of creatures: The Companion Animal Parasite Council has identified eight species of ticks and five species of fleas that prey on pets. Some of these parasites aren’t terribly picky about where they land, either — neither the “cat” flea nor the “dog” flea stick to the species it’s named for, and ticks hop indiscriminately onto pets and people. As a result, people and pets often share some of the diseases caused by the pathogens that these parasites transmit, including Lyme disease.
People and pets also, of course, share the scratching. You’re probably already feeling itchy just reading about fleas and ticks, so I’ll go right to our VPI claims data for 2013. In order of frequency, here are the top five flea and tick related claims:
Veterinarians stress preventive care for good reason, and that’s especially true when it comes to fleas and ticks. While a simple, overlooked flea infestation often can be resolved by following your veterinarian’s advice, for some of the other health issues on this list, prevention is truly the only way to go. In the case of flea allergy dermatitis, for example, every flea bite can trigger a flare-up of misery. That makes flea control a critical part of maintaining quality of life for these pets.
Ask your veterinarian about recommendations for effective parasite prevention and control. Though most of these strategies will likely involve flea-and-tick preventives, other strategies, such as frequent vacuuming and removing ticks promptly, can be highly effective as well.
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When you think about it, the pancreas is a lot like a cat: It typically goes about its business (of producing hormones and digestive enzymes) without a lot of fuss, but it definitely has a volatile and mysterious side that shows itself when the organ becomes inflamed.
The pancreas pulls double duty in the body. It produces hormones such as insulin and glucagon, which help maintain an appropriate level of glucose in the blood. But it also makes digestive enzymes that enable the body to use carbohydrates, fats and proteins for energy. That multitasking is all well and good, but it can cause confusion when a veterinarian is trying to diagnose a cat with pancreatitis.
Pancreatitis is one of the most baffling diseases veterinarians see in cats. The signs of pancreatitis can be difficult to spot. Loss of appetite, lethargy, dehydration, weight loss, vomiting, abdominal pain and diarrhea can be symptoms of pancreatitis — and of many other illnesses. And some cats won't present with any of thse symptoms: My own family cat, Varmie, had none of the typical signs of pancreatitis except for loss of appetite. Varmie’s case is a good example of why you should take your pet to the vet if you notice any changes in appetite, thirst, activity or elimination.
Another reason pancreatitis is such a puzzle is because we usually don’t know what causes it. In 90 percent of the cases we see, we don’t know why the pancreas has become inflamed. In cats, pancreatitis isn’t associated with obesity, high-fat foods, steroids or other drugs, as it is in dogs, but it can be linked with liver and/or inflammatory bowel disease. In addition, cats as young as 5 weeks and as old as 20 years can develop pancreatitis.
As with any feline health problem, diagnosis begins with a medical history and a physical exam. Common signs we may see on examination of a cat who turns out to have pancreatitis are dehydration, low body temperature (or sometimes a fever) and icterus, a yellowish discoloration of the gums, whites of the eyes and ear tissue. We may also feel a mass in the abdomen, or note that the abdomen is painful when palpated.
Diagnostic tests don’t give us a definitive answer, but they can sometimes help. A blood test that measures what’s called pancreatic lipase immunoreactivity (fPLI) can give some useful answers, but results may not be available for a week or more.
An abdominal ultrasound may or may not indicate that the pancreas is inflamed, but certain findings are consistent with pancreatitis. On the other hand, some cats show no abnormalities on ultrasound but still have severe pancreatitis. One of the advantages of an ultrasound is that it may rule out or detect other diseases that cause similar symptoms.
A biopsy would let us know for sure that we were dealing with pancreatitis, but it’s a very bad idea to anger the pancreas. Poking and prodding at it to obtain a biopsy sample can trigger inflammation and make the condition much worse. Usually, our goal is to be as noninvasive as possible with both diagnosis and treatment.
Often, the best we can do is to start treating the cat’s symptoms while we wait for the results of the fPLI test. For instance, your veterinarian may prescribe anti-emetics if your cat is vomiting or pain-relief medication if the abdomen is tender. Antibiotics may be prescribed if your vet suspects that bacteria from the intestinal tract have traveled up the bile and pancreatic ducts to the pancreas, causing infection and inflammation. Cats who aren’t eating may need hospitalization for tube feeding.
Intravenous fluids are important, too. Giving fluids makes up for any fluid loss the cat may have experienced from vomiting, diarrhea or simply not drinking enough water. It also helps to improve blood flow through the pancreas.
If you’re lucky, your cat will have only a single acute bout of pancreatitis. Unfortunately, some cats develop chronic pancreatitis. That’s a low level of constant inflammation that can cause the cat to become deficient in digestive enzymes. Cats with chronic pancreatitis may need enzyme supplements to help them digest their food.
Pancreatitis isn’t easy to diagnose or treat, but it’s something your veterinarian may consider when nothing else seems to explain your cat’s illness.
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Never leave your pet in a parked car. Temperatures inside parked cars can rise rapidly and cause heatstroke, organ and brain damage, and even death. Just imagine how terrible being trapped in a hot car would be — and then imagine wearing a fur coat at the same time!
Our pets would never leave us in the parking lot. Let’s not do it to them.
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May 23 is National Heat Awareness Day, and humans aren't the only ones who can become sick when it's hot outside. Pets can suffer from heat stress, too. To remind you to keep your dogs and cats safe from the heat, we found 15 photos of pets staying cool on hot summer days.
With the summer season upon us, the Centers for Disease Control has started to issue warnings about sun safety to help protect Americans against sun-induced tumors such as melanoma. Since pets don’t sunbathe or go the tanning parlor — both risky behaviors when it comes to skin cancer — and are covered in fur, how could that dark spot on your Fluffy or Fido be a melanoma? Melanoma in dogs and cats does not look like it does in people, but it can still be deadly. Here’s how you can recognize the dreaded disease in your best friend, despite its resemblance to other problems.
In my daily oncology practice, I often see pets because of a concern on the part of a human family member about dark spots that have appeared on a pet’s skin. The good news is that skin melanoma is quite uncommon in dogs and cats. There are some common pet skin conditions that often look like a possible melanoma, however, and they can get everyone concerned. For example, orange tiger cats commonly develop flat, round, pigmented areas surrounded by normal skin on their lips, gums, nose and eyelid margins. Known as lentigo simplex, the benign lesions require no treatment and do not transform into melanoma.
Another noncancerous skin abnormality often mistaken for melanoma in a dog is a macule, a round to oval, flat, pigmented area that often occurs after a skin infection. Before the skin developed pigmentation, the area may have been red, itchy and surrounded by a flaking, peeling ring. The lesions are not cancerous, but the infection may require antibiotic treatment. Macules are most readily seen on sparsely haired canine tummies.
You can help your doctor detect a melanoma on your own skin, since nearly every inch of human skin can be seen. Your dermatologist can then biopsy suspicious lesions. The most common location for melanoma in your dog, however, makes this kind of easy discovery nearly impossible. That’s because melanoma is the most common oral tumor in dogs. (To a lesser degree, oral melanoma is also occasionally seen in cats.) In a reluctant patient, getting a good look in a dark mouth for a black tumor is no easy task. A bad case of hound halitosis may wind up being your first clue of a melanoma in the mouth. Oral melanomas are most commonly black, raised masses that frequently bleed. Pet owners may notice blood-tinged saliva or blood on their pets' teeth. Your veterinarian may need to sedate your pet to see the tumor and perform a biopsy in order to make a diagnosis. Surgery, radiation therapy and a melanoma tumor vaccine are just some of the common treatments for oral melanoma, but more and better treatments are needed, since a cure is rare.
Feline ocular melanoma may be the most difficult form of melanoma to recognize. At first, the iris — the colored part of the eye — may look as if it simply has a freckle on it, but, as time goes by, that freckle expands over more and more of the iris. If you notice a dark spot on your cat’s iris, consultation with a veterinary ophthalmologist is critical to determine if there is a malignancy. If an iris melanoma is diagnosed, frequent ophthalmologic examinations are required to determine if the eye needs to be removed in order to stop the spread of the deadly tumor. Although heartbreaking, removal of the eye can keep your cat alive and well for many years.
Tricky melanoma may also masquerade as a broken toenail in your dog. Melanoma of the toe typically occurs at the junction between the toe and toenail. The tumor weakens the nail, which snaps off without provocation. Both a broken toenail without an apparent cause or a broken toenail and a very sore, swollen toe could be signs of a melanoma. When you take your dog to his veterinarian for a broken nail, don’t be surprised if he recommends an X-ray. The image will uncover any bone destruction typical of melanoma in the toe. Removal of the toe and treatment with an anticancer vaccine can result in prolonged survival in many dogs.
Although the locations of melanoma in a dog or cat differ from the typical locations in people, melanoma is an aggressive cancer regardless. Whenever you notice a lump, bump or other abnormality in your pet, it is best to have your veterinarian check it out to keep your pet as healthy as possible.
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