For Pet Owners
Here you may find answers to some of your initial concerns about your pet's health.
- I think my pet has cancer.
- I’ve just learned that my pet has cancer.
- Is pathology testing important?
- A word about cancer statistics
- What should I feed my pet with cancer?
- What about complementary and alternative therapies?
- Deciding about amputation.
- How can I take my pet to see an oncologist in person?
I Think My Pet Has Cancer
Does my pet have cancer?
Cancer is the process where normal cells in the body undergo excessive or unrestrained growth. Cancer can occur in any bodily organ and can travel from one part of the body to another distant part by the blood or lymph system. There are more than 100 different types of cancer that can affect our pet companions.
How common is cancer in pets?
Cancer is usually more common in older animals, and is the cause of death in almost half the pet population over 10 years of age.
What are the signs of cancer in a pet?
Most often, a pet’s caregiver will notice a mass on the body, or possibly enlarged lymph nodes. Sometimes the animal may have a reduced appetite and less energy. There may be changes in bowel movements, or there may be an unusual odour from the mouth of a pet with mouth cancer. While the initial lump or cancer is often the most obvious to a caregiver, other organs of the body may become affected (metastasis), and the function of normal cells may be compromised. For example, liver damage may occur because of the expanding tumour cell population in the liver, and decreased exercise tolerance may happen when the lungs are affected. Normally the bone marrow produces the majority of the blood cells. Tumour cells in the bone marrow can cause fewer normal cells which aid in blood-clotting and infection-fighting to be available. The pet is then susceptible to bleeding and infection.
The affected pet may develop what are called “paraneoplastic syndromes” or tumour-associated conditions. For example, there may be abnormal proteins or too much calcium in the blood due to secondary effects of the cancer. These syndromes themselves can cause acute, life-threatening problems; this is why careful monitoring by the veterinarian is important. Many of these signs are non-specific, indicating problems other than cancer, and a visit to the primary care veterinarian is always the first step when you suspect cancer in your pet. If a diagnosis of cancer is confirmed, your veterinarian may suggest a biopsy, lymph node evaluation, chest and abdominal radiographs, and standard blood tests and urinalysis, but they may also discuss more complicated procedures.
What are the causes of cancer in a pet?
Cancer is caused by a variety of factors, potentially involving viruses, genetic components, exposure to carcinogens, and other unknown factors. In this respect cancer in pets is the same as in any other animal, including humans. Some cancers are preventable in pets, such as breast (mammary) cancer in dogs which rarely occurs after early neutering.
Know your pet’s medical history.
Particularly when seeing a veterinarian for the first time, it’s important to give a complete picture of the health status of your pet. If your pet has several health problems or a long history with one, be sure to provide a history of events, recurrences, treatments, medications, and outcomes associated with the condition. A written list can save time and ensure completeness.
Start with a primary care veterinarian.
Primary care is a term for the branch of medicine concerned with your pet’s overall, general well being. It is important to have a veterinarian who is familiar with your pet’s medical history and who can serve as their “care ambassador”.
Specialist veterinary care
Although your primary care veterinarian is an integral part of the cancer care for your pet, often you may need to visit an expert in a specific area of veterinary science. These veterinarians have undertaken further training and have achieved certification by various veterinary Colleges. They are often called Specialists.
Cancer in Pets
What is cancer?
Cancer is the process where normal cells in the body undergo excessive or unrestrained growth. Cancer can occur in any bodily organ and can travel from one part of the body to another distant part by the blood or lymph system. There are more than 100 different types of cancer that can be grouped into one of six major categories:
- Sarcomas: Cancer that begins in tissue that connects, supports or surrounds other tissues and organs (such as muscle, bone and fibrous tissue).
- Carcinomas: Cancer cells that originate in tissues that cover a body surface, line a body cavity or make up an organ.
- Lymphomas: Cancer that occurs in cells that make up an important component of the immune system and protect the body’s cells.
- Leukaemias: Cancer that occurs in the blood-forming tissues and blood cells.
- Skin cancers: Cancer that originates in the skin cells; the most common in dogs being mast cell tumour.
- Brain tumours: Cancer that originates in the brain cells.
What are the causes of cancer in a pet?
Cancer is caused by a variety of factors, potentially involving viruses, genetic components, exposure to carcinogens, and other unknown factors. In this respect cancer in pets is the same as in any other animal & humans.
What should I do?
When you hear the word “malignant,” it’s hard to focus on anything but what it may mean for your pet. What are the treatment options? What will work? How will having cancer affect your pet’s quality of life?
First, most cancers require more than one form of treatment to effectively fight the disease. This can mean using as many as four different cancer therapies, including Surgery (surgical oncology), Chemotherapy (medical oncology), Radiation therapy (radiation oncology), and immunotherapy. This requires a multi-disciplined cancer care team that develops, coordinates and monitors all aspects of your pet’s treatment plan.
Start with a primary care veterinarian.
Primary care is a term for the branch of medicine concerned with your pet’s overall, general well being. It is important to have a veterinarian who is familiar with your pet’s medical history and who can serve as their “care ambassador”.
Know your pet’s medical history.
Particularly when seeing a veterinarian for the first time, it’s important to give a complete picture of the health status of your pet. If your pet has several health problems or a long history with one, be sure to provide a history of events, recurrences, treatments, medications, and outcomes associated with the condition. A written list can save time and ensure completeness.
Make sure all members of the cancer care team are informed.
If your pet develops a condition that requires one or more specialists or needs surgery, it’s important that all members of your pet’s veterinary medical team have complete and consistent information. So when you visit one veterinarian, make sure you have the names and contact numbers of any others involved with your pet’s care and keep them apprised of your pet’s condition.
Know when and how you will receive test results.
Assume nothing. Ask when and how you will be notified of test results. If results do not arrive when you expect them, contact your veterinarian and ask about them.
Specialist veterinary care
Although your primary care veterinarian is an integral part of the cancer care for your pet, often you may need to visit an expert in a specific area of veterinary science. These veterinarians have undertaken further training and have achieved certification by various veterinary Colleges. They are often called Specialists. Medical oncology is the general study and treatment of cancer. Medical oncologists are trained in the prevention, detection and medical treatment of all forms of cancer.
Surgical oncology is the specialty concerned with the physical removal of cancerous tissue. Sometimes, surgery is augmented with other forms of care, such as chemotherapy or radiation therapy. Surgical oncologists have specialty experience in treating distinct types of cancer, from breast, bone and lung cancer to cancers that occur within the abdomen, as well as skin cancer. Internal medicine deals with the function of the internal organs, such as the liver and lungs, plus the diagnosis and treatment of associated problems. Internists often provide the first contact for an unspecified internal illness or problem. They may diagnose and treat the problem themselves, or work in conjunction with another specialist (such as an oncologist) for more focused diagnosis and treatment.
Emergency medicine is the specialty that deals with critical health and accident cases, where immediate treatment can sometimes mean the difference between life and death.
How is my pet likely to respond to treatment for cancer?
For cancer in dogs and cats, expected remission times and life span, or “prognosis”, is highly variable and depends on a number of factors, the most important of which is the type of cancer as diagnosed by biopsy.
Other factors that will influence your pet’s prognosis include:
- The stage of the disease, which reflects the number, location, and size of major populations of tumour cells in the body.
- Whether your pet is feeling sick or not. Loss of appetite is one of the most important symptoms.
- Histologic grading: the specific appearance of tumour cells and their pattern of infiltration in various tissues (what the pathologists reports from a biopsy specimen).
- The pet’s response to therapy.
- The presence of paraneoplastic syndromes, previously described.
- The treatment chosen and the care given by the owner and veterinarian.
It is difficult at this time in veterinary medicine to accurately predict the prognosis for a given individual pet because not enough is known about the specific way the above factors influence prognosis for the wide variety of cancers that occur.
In general, pets that are not feeling sick and are diagnosed early in the course of tumour growth have a better chance of remission with treatment. Untreated pets with malignant cancer often live 2 months or less, but this varies greatly depending on the type of tumour. Lymphoma and osteosarcoma are two common cancers in dogs. With therapy, many dogs with one of these cancers live 9 months to 1 year. Therefore, a reasonable goal is a 1 year survival. Occasionally the pet will live much longer, up to 2 1/2 years or more. Some animals are truly cured of cancer, but this depends greatly on the tumour type.
Cancer treatment
The treatment of cancer has evolved over the last few decades to parallel treatment in humans, with certain differences. The important difference between cancer therapy in humans, and that offered for pet animals, is in the goals of therapy. In humans, many cancers are cured, and cancer survivors may enjoy many decades of comfortable life. For this reason, treatment of cancer is aggressive and may be associated with side effects. While pet animals are very similar biologically to humans, the chance for survival of decades is remote. Therapies are therefore directed at preserving quality of life; and tumour control, or remission, is the aim rather than cure at any cost.
The goal of veterinary cancer therapy is to achieve a “complete clinical remission” or to make the pet as normal as possible with no outward evidence of cancer. Often the treatment starts with surgery. If the surgeon is unable to remove all the tumour cells without causing compromise to your pet’s quality of life, then radiation therapy may be offered as a follow-up. If the tumour has spread to other sites, or if the risk of spread is very high, then treatment may involve the use of anti-cancer chemotherapy medications. They are used in a set format, or “protocol”. Various such protocols exist, using slightly different drug sequences and dosages.
It is important to recognize that although cancer is a rarely curable disease, your pet can be treated in such a way that a high quality of life is achieved following diagnosis. In this respect, it is similar to treating heart or kidney disease, which can also be fatal. Remember that one of the most important factors influencing your pet’s quality of life and remission time is the interest and dedication of you and your veterinary care team.
The Importance of Pathology in Veterinary Oncology
Everybody knows the signs of cancer, but just because the signs are present doesn’t mean it is cancer, or what type.
So, how do we as veterinarians and you as a pet owner know whether or not to worry about that lump on your pet?
Once in a great while an oncologist or very experienced general practitioner might be able to give a strong indication of whether a lump is something to worry about, and even what it might be, based just on a physical exam. But the huge majority of the time the decision requires pathology. Yes, veterinarians are special but even our eyes and our fingers are not microscopes!
And, “if it’s worth taking off, it’s worth sending in” (that means, if you are having a lump surgically removed from your pet there is rarely a reason not to have the veterinarian send it in for pathology – if you’re absolutely certain it’s benign then why are you having it removed?
As oncologists seeing pets with cancer on referral, admittedly we only hear about the times it goes wrong and not about the many times that nothing bad eventuated. But, many is the time that we’ve wished for a time machine to diagnose a cancer that first showed signs weeks, months or even years ago.
Being able to obtain diagnostic samples and establish a definitive diagnosis is crucial to formulating a prognosis and developing an effective treatment plan for any pet with cancer and it is a big part of what veterinarians and veterinary oncologists do. This is really square one.
Moreover, we may not even be happy with just sending a sample in to a pathology laboratory. We might even be picky about which lab and which pathologist; because just as a veterinary practitioner might be more interested in one type of problem than another (for example, reproduction or dermatology); not all pathologists are equally focused on oncology – some might be more interested in dermatology, or bone pathology, or infectious disease. Therefore, for a veterinary oncologist, identifying veterinary pathologists that excel in oncologic pathology is a major priority when developing an animal cancer treatment team.
As oncologists, we don’t just read the diagnosis line either, we read the whole description because there’s often additional information in there that may be helpful. We’re interested in more than just “Is it cancer or not?” but also the tumour type, and in many cases the “grade”, and other characteristics like the “surgical margins” and “mitotic index”. Depending on the individual case, all these may factor into the prognosis for the patient and a plan of how best to approach this cancer.
But wait, there’s more! We almost always want to know other things too, because another old motto is “treat the patient, not the tumour” – so we also need to know all about their overall health aside from the cancer. This also feeds into the overall prognosis and treatment plan. This means that the veterinarian needs to run “general health panels” – blood and urine tests that look at the whole pet, not just the cancer.
In the diagnostic process, we might suggest cytopathology (or cytology) (usually the sample is a “fine needle aspirate”) and / or histopathology (usually the sample is a “biopsy”). These are often read by two different pathologists – again, they have their areas of expertise too. In some cases veterinarians might suggest going straight to histopathology, as this is usually needed to provide all the information we need to make a final plan. But in some cases we might suggest starting with cytology and then proceeding to histopathology depending on the results. The pros and cons of these two types of pathology, and when to use which one, depend on the individual case.
Sometimes even histopathology doesn’t give us all the information we want about a pet with cancer, and we need to request additional tests to be run on the sample, including various types of special stains and subtyping tests. We only recommend these tests if the information to be gained will be helpful to the pet. Sometimes if the pathologist is having difficulty classifying a particular tumour and special stains or other tests are needed, this can take more time and it can become frustrating for a pet owner. But, as much as we wish that pathology were an exact science, it isn’t. There is subjectivity in it and even the very best pathologist can’t always make a final diagnosis “just by looking”. In fact, in our experience, the best pathologists are the most likely to offer additional tests because they are the ones who are most aware of the subtlety and subjectivity of their discipline, and also the most aware of the usefulness of the extra information that can be gained from these tests and take the trouble to make them available.
Although on this website we tend to focus on the implications of a cancer that is missed; there is another side to this coin. That is, what if we assume that a lump IS cancer when it actually isn’t. In veterinary medicine, that can be equally life-threatening because if a pet owner is mistakenly given a grave prognosis then they may choose to have their pet euthanized when it wasn’t really necessary. Or, they may just miss having the correct condition appropriately treated. Here are a few examples:
Brodie is a bouncy and loving 10 year old desexed male Staffy. He came to see his veterinary oncologist with multiple lumps in and under his skin. He had been treated a year earlier for a mast cell tumour, so when he came in with multiple lumps the obvious fear was that his mast cell disease had disseminated. Based on this assumption, his prognosis would be considered grave and many pet owners would have chosen euthanasia for him at that time. Luckily for Brodie though, his dedicated owner agreed to have histopathology done on the lumps. Guess what, not only were they not mast cell tumour but they weren’t cancer at all – they were a rare infectious disease called canine leproid granulomatosis, and he was cured with a course of the correct antibiotic.
Every cat owner fears oral squamous cell carcinoma. This is one of the most relentless cancers of older kitties and erodes quality of life very quickly. A typical presentation is of a proliferative and erosive lesion under the tongue in an older cat, and certainly a lesion of this appearance in an older cat is extremely worrying. So when beloved 12-year old China presented with a history of drooling and halitosis and a peek under the tongue disclosed the dreaded lesion, it was most fortunate that her veterinarian performed a biopsy and made a diagnosis of eosinophilic granuloma. Had a diagnosis been made based only on the appearance she would have been either treated incorrectly or euthanized needlessly.
When your veterinarian suggests what seems like a lot of tests for your pet in the process of diagnosing or staging a possible cancer, it is important that you understand what each test entails and the reasons for it. But do remember that the more we know about your pet the better we can help!
Dietary Recommendations For Pets With Cancer
Food and eating are an important aspect of quality of life for pets as well as for people; and maintaining a good dietary intake helps to make a patient's body more resilient to both disease and treatment.
Caregivers often wonder how best to feed their pets with cancer. As quality of life is always the primary consideration for care of pets with cancer, it’s important to remember that the best food is not only nutritionally complete and appropriate to the individual condition, but should also be enjoyable!
Here are a few tips to help you optimize your pet’s enjoyment, as well as his or her intake and nutritional status:
- Ask your veterinarian to help you make sure that pain and / or nausea and other metabolic imbalances are controlled to the extent possible.
- Ask your veterinarian whether appetite stimulants would be appropriate.
- Make any dietary changes gradually to avoid causing digestive upsets, diarrhoea, and even pancreatitis.
- Warm the food to body temperature before feeding.
- For cats, provide food throughout the day.
- If your pet is unable to eat, ask your veterinarian to discuss with you whether a feeding tube would be appropriate.
In choosing a commercially available diet or preparing your own:
- Choose a diet or use ingredients that your pet prefers.
- Avoid excessive starches and sugars (carbohydrates).
- Use high quality protein sources (meat, fish).
- Consider supplementing with n-3 fatty acids, such as DHA or fish oil.
Pets have different dietary requirements than people do, and it’s important not simply feed your pet human food. High quality commercially prepared pet foods are nutritionally balanced for pets, so are a simpler option than trying to home-cook a balanced diet. Hill’s Prescription Diet n/d is optimized for dogs with most types of cancer, and for dogs that enjoy it, is probably the simplest best choice.
If you prefer to home-cook for your dog, try the “Ogilvie Canine Cancer Homemade Diet”. Remember, it is more important that your pet eats, than it is for your pet to eat a specific cancer diet; if your pet refuses to eat the prescribed diet, discuss alternatives with your veterinarian rather than have your pet have a suboptimal caloric intake.
Finally, a word of caution about seemingly magical supplements offered in magazines, health food stores, and on the internet. There is certainly potential for nutritional and herbal supplements to be effective, but many formulations haven’t been adequately evaluated for efficacy or side effects.
We strongly recommend consulting with a veterinarian qualified in alternative and complementary medicine or naturopathy to help you choose what may or may not be appropriate for your pet.
Complementary and Alternative Therapies in Veterinary Oncology
Many owners of a pet with cancer wish to try anything that may help their pet, and in doing so are interested in trying complementary and alternative therapies either instead of or in addition to “conventional” therapies.
We fully understand this; but there are some hazards that you should be alert to. We take a “holistic” approach to patient care, in that we take the whole pet into account in our recommendations (“treat the patient, not the cancer!”) and always prioritize quality of life. But confusingly, the word “holistic” is also used to describe a medical approach focused on complementary and alternative therapies in preference to conventional therapies. We don’t prescribe complementary and alternative treatments because, firstly, it is a body of knowledge in itself, and secondly, our philosophy of medicine is to prioritize evidence-based decisions where possible. We do strongly recommend that if you want to explore complementary and alternative therapies to see a veterinarian specially trained in that area. The internet is a boon for salespeople who capitalize on the fears and hopes of owners of pets with cancer.
Typically these claims lack data from controlled clinical trials showing safety and efficacy, and because the substances are not regulated as drugs, they are not required to be produced according to GLC so contamination and inconsistent potency are relatively common problems. Once data showing safety and efficacy is available for any particular substance, it becomes part of “mainstream” medicine. There are little published data on most of the “alternative” medicines. It is also very difficult to identify any potential toxicity, as most patients are receiving multiple different types of supplement, which confuses the issues. Other compounds may cause toxicity; for example, although rare, xiao-chai-hu-tang is documented to cause acute hepatic disease.
This is based on a single case report, but so is the “efficacy” on which it is being prescribed for many patients. It also has been associated with interstitial pneumonitis. Some direct experience we have is that some of our patients also receive Five Mushroom Extract; used in the assistance of treatment for cancer and chemotherapy for “immune support”; consisting of various Chinese Mushrooms, including Cordyceps, Shitake, Reishi, and Tremella. We had one patient that developed severe and acute liver toxicity and possible gastric ulceration that continued despite stopping chemotherapy but then resolved after ceasing the alternative medications (but there were approximately 20 of them so it’s not possible to identify the actual causative agent), and those signs did not recur when chemotherapy was restarted.
In dogs with lymphoma, the only study published so far has been for Maitake mushroom as a treatment. There was no decrease in lymph node size (objective response) seen in any of the dogs. Thirteen dogs developed progressive disease before the 4th week. Another study investigated Coriolus versicolor (Yun-Zhi) for dogs with haemangiosarcoma, and claimed improved survival in the abstract, but in the article, the improvement in survival was not significant statistically, and was based on 5 dogs; there was no discussion about tumour grade (which markedly affects survival). An interesting statistic to consider when thinking about where the new “cures” for cancer come from is that between 1990 and 2005, there were 920 anticancer compounds that underwent clinical trials (so these are ones that got beyond the initial testing of in vitro and mice testing and into human subjects) in the USA.
Of these only 32 were found to be effective. Many got as far as late-stage clinical testing before being found to be ineffective. It is important when evaluating whether to use untested “alternative” drugs in your pet, that the likelihood of finding true benefit is probably no greater than for traditional drugs; in other words, it would have only a 3.5% chance of actually benefiting him or her, but without the testing and analysis that we require “conventional” drugs to go through, we will never know which of the alternative medications might work. Separate to that is the question of “supplements” to reduce the toxicity of chemotherapy. In truth we do a good job of this with antiemetics and antibiotics, so unless there is a specific problem with an individual patient’s chemotherapy, we are not sure there is an advantage to adding more chemicals (even if “natural”). However, we totally understand that owners wish to try anything that may help their pet, and we try to support this.
Many of our patients do also receive complementary and alternative treatments in addition to their conventional treatments, and if it is done safely and sensibly there is usually no problem with this. We do advise avoiding antioxidant supplements at the same time as chemotherapy, as antioxidants can interfere with the mode of action of chemotherapeutics, and thus reduce the effectiveness of treatment.
So again, if you really want to pursue complementary and alternative treatments, see a veterinarian specially trained in that area. Be aware that there are many unscrupulous salespeople out there ready to prey on uninformed people – and a plethora of “offerings” – so you need to do a lot of reading to sort out what is what. This phenomenon isn’t new of course, the internet just makes it easier.
We have found one of the best explanations of these concerns in a veterinary website, voiced by SkeptVet; http://skeptvet.com/Blog/2014/03/tumexal-wonder-drug-of-snake-oil/.
The Cancer Council of Australia has a booklet called “Understanding Complementary Therapies” that you may want to have a look at (http://www.cancercouncil.com.au/1987/b1000/complementary-therapies-40/understanding-complementary-therapies-using-therapies/?pp=74162&cc=4233&&ct=35).
Deciding About Amputation
In the course of cancer treatment, surgery can play a major role. More cancers are cured by surgery than by any other treatment modality.
How Can I Bring My Pet to See a Veterinary Oncologist in Person?
While in many situations your family veterinarian is the best person to care for your pet, there are times when referral is appropriate.
We can help find an oncologist for your pet with cancer in several major metropolitan areas in Australia and worldwide. Please ask your veterinarian to contact us for advice.
