The most feared word of any dog owner is “cancer”. For dog owners whose pets are part of the family, the news that your dog has cancer is devastating. However, although it is hard to take in and very frightening, the more information you have and the more knowledge about treatment options, the easier it will be for you to decide what steps to take to do the best you can for your dog.
Understanding a little about the disease, its various forms, and the possible outcomes will at least make things clearer and assist you in making decisions along the way. You will understand what changes your dog will go through, what is likely to happen to him, and what treatment and complementary therapies are available for him.
In simple terms, cancer is abnormal division of the cells and multiplication. Cells in all organs and of the body grow and then divide as part of the normal life cycle. The division of the cell results in two cells, which is why it is known as “multiplication” of cells. When the multiplication of cells is unchecked, they eventually destroy normal tissues and organs. Cancer can occur in any part of the body, and at any stage of life.
The good news is that the growth in “Veterinary Oncology” as a study field and the dedicated work of researchers and veterinary cancer specialists, cancer treatment for dogs has evolved a very long way in the past thirty years.
Many types of cancer CAN be cured through conventional treatments, or knocked into remission for increasingly longer periods of time. Due to the synergy and cross over of veterinary medicine to human medicine and back again, many cancer treatments available for people are also available for dogs, and new cancer treatments are being developed every day.
There are many pioneering organizations making efforts to research and work on canine cancer treatments in the hopes that new discoveries and drug therapies will provide a treatment where currently fatal cancers can be halted before that stage or even cured.
TREATMENT PHILOSOPHY OF CANINE CANCER
Cancer treatment for animals is always focused on providing the animal with the highest possible quality of life for the longest amount of time possible. That is why dogs typically do so well while undergoing chemotherapy.
Humans by comparison rationalize and understand that the of the rigors of chemotherapy will make us very ill and we will suffer severe side effects in some cases but we have the mental capacity to know we will feel ill before we get better.
The philosophy of quality of life for your dog is extremely important since they cannot consent to their own medical treatment. Your dog’s quality of life could be destroyed and cause him considerable distress where an aggressive treatment that could cure the cancer completely is used, but would sacrifice your dog’s quality of life to the extent where he would not be able to function on his own and would need round the clock nursing.
Veterinary treatments of cancer keep the dog in a state where he can perform basic tasks such as eating, drinking, and toileting and retain some comfort. Many owners will take responsibility for the dog’s needs of course but if the treatment will take away the quality of life of your dog, it is a matter for discussion between you and your veterinarian. This is one of the most difficult diseases for you as a dog owner as ultimately you are responsible for his welfare. Some canine cancer support groups out there will help you through a difficult time or decision.
TYPES OF CANINE CANCER
Normal Cell Division. Cell division is rapid in young growing pups, to allow for the quick growth in body size. As dogs become adult, this cell division slows and stops, until only cells of the skin, bone marrow, and intestine continue to divide throughout life. The body has an inbuilt monitor that keeps a close check on the balance between cell multiplication and cell death, so there is always just the right number of cells in an organ. Genes are responsible for controlling cell division and some genes switch on cell division and some switch cell division off thus maintaining the right balance.
Abnormal Cell Division. All of the causes of cancer are not fully known, but genetics, environment, and the state of an individual’s immune system are all thought to play a role. The outcome of treatment depends on how successful the therapy is at stopping the abnormal cell divisions. Abnormal cell division puts the body out of balance and can be caused by damage to a cell’s DNA. This in turn affects the genes involved in controlling the rate of cell division.
The body somehow loses the ability to kill the cells with damaged DNA resulting in abnormal cells multiplying out of control. These cells commonly known as cancer cells can spread throughout the body leading to organ failure and death.
Cell division and multiplication occurs in every organ of the body. This means cancer can occur anywhere. However, some cancers occur more frequently in our dogs than others and different breeds have more susceptibility to cancer.
The most prevalent cancers in all dogs are:
Breeds that tend to have a higher incidence of cancer include Golden Retrievers, Boxers, German Shepherds, Cocker Spaniels, Flat Coat Retrievers, West Highland White Terriers, Rottweilers, Doberman Pinschers, Schnauzers, Bernese Mountain Dogs, Great Danes, Greyhounds, and Standard Poodles.
Breast Cancer in Dogs
Breast cancer is most common in female dogs, but it can occur in male dogs also. It usually occurs in middle aged to older dogs, particularly if they are not spayed or were spayed later on in life. This is because the hormones associated with the heat cycle can trigger abnormal growth of the mammary cells. This is a good reason to spay your female puppy if she is not going to be bred from.
- Symptoms: The symptoms are firm, irregular lumps or masses that are felt under or near a nipple. The lumps usually appear in the mammary glands between the back legs. They grow rapidly and can develop smelly ulcers on top. Veterinarians rely on a biopsy to confirm that it is cancer. Sometimes the lumps are benign, but there is a real risk that these benign lumps will turn cancerous over time. It may be a good idea to remove the lump before it becomes dangerous.
- Treatment: Treatment for this type of dog cancer is surgery to cut away the lump, followed by chemotherapy. If the dog is female, you will be advised to have her spayed to remove the chances of hormonal activity that could set off the cancer again. Unfortunately, in many dogs, by the time breast cancer is diagnosed, it has already spread to the internal organs, and the outcome is not good.
Canine Osteosarcoma (Bone Cancer)
Osteosarcoma is the most common bone cancer in dogs. It tends to occur in middle aged, large breed dogs, and it most often develops at the ends of the long bones of the leg.
- Symptoms: The first indication that there is a problem is usually when the dog starts to limp. The limp progressively gets worse, and painful swellings may develop where the tumour is growing. The cancerous bone is not as strong as normal bone, and it may suddenly break. A veterinarian can usually make a diagnosis based on the dog’s age and breed and by taking an x-ray of the sore leg. A bone biopsy will give a definite answer. Bone cancer is extremely painful, and by the time it is diagnosed, it has usually already spread to the lungs.
- Treatment: Treatment commonly involves amputation of the affected leg. Most dogs do very well with only three legs, and they feel better with the painful tumour removed. Chemotherapy can extend their life, but for many dogs, the survival rates with osteosarcoma are one year even with treatment.
Skin Cancer in Dogs
Skin cancer is normally thought of as being caused by too much time spent in the sun. This is the case with dogs too, but the most common skin cancer is not related to sun exposure at all.
- Symptoms: Skin cancer tumours are called mast cell tumours, and they normally appear as fast growing ulcerated nodules on the legs or body. They can be aggressive and spread to the internal organs from time to time.
- Treatment: Treatment involves surgical removal of the tumour where a wide margin of skin is also removed around the tumour to ensure all traces of cancer are removed. Follow up treatment may be radiation or chemotherapy. The outlook is very positive after skin cancer and your dog is likely to enjoy a good quality of life for several years.
Canine Mouth Cancer
Different types of tumour may develop in a dog’s mouth and throat. They all cause similar symptoms: Most tumours are not found until the disease is fairly advanced, so it is a good idea to regularly look inside your dog’s mouth. These tumours can spread into the bone of the jaws.
- Symptoms: The symptoms of mouth cancer are bad breath, pain and difficulty eating, and sometimes bloody saliva.
- Treatment: Treatment often includes surgical removal of part of the jaw. Although dogs do seem to cope with this, it can make eating more difficult. This is often followed up with radiation therapy to try to increase survival time. These tumours do not have the best prognosis and many dogs do not survive for much more than a year after diagnosis.
Lymphatic Cancer in Dogs
Lymphocytes are cells, which are produced in the bone marrow, and are part of the body’s immune system. As with any other type of cell, they too can become cancerous. When this occurs, it is called Lymphoma and damage is possible to any organ that has lymphatic tissue. The most common areas for lymphoma to develop are the lymph nodes, the gastrointestinal tract, the bone marrow, and the skin.
- Symptoms: Symptoms vary depending on which part of the body is affected, but in most cases, dogs will be come ill and may vomit, stop eating and develop a fever. Untreated, the dog rarely survives more than a few months.
- Treatment: Chemotherapy is successful in many cases and can lead to remission where the signs of cancer disappear, and the dog is essentially normal. Remission can last for as much as a year, but the cancer often reappears.
This is a perplexing problem for veterinary oncologists as if the cancer did not reoccur; this would be quite treatable with a positive prognosis.
INFLUENCES ON THE DEVELOPMENT OF CANCER IN DOGS
There are four main influences in the development of cancer in dogs, some of them can be managed to reduce the risk of the disease.
Genes have been identified in some breeds of dog that seem to increase the risk of them developing cancer. German Shepherd dogs often develop hemangiosarcomas (a tumour of blood vessels), whereas osteosarcomas are common in Rottweilers. The fact that some types of tumours are more common in certain breeds suggests that these tumours have a genetic basis. It could be possible that some dogs are born with damaged DNA in his cells hence predisposing him to these types of cancer.
Infection and Inflammation
Papilloma is a virus that causes harmless growths in a dog’s mouth. However, there appears to be a link between papilloma virus infection and the tendency for a dog to develop aggressive cancer of the mouth.
Chronic inflammation of an area may also trigger the growth of cancer. One example of this is when a broken limb has been repaired with plates and screws. If the screws become loose over time, then the irritation to the bone may lead to osteosarcoma in the area.
There are very strong links between hormones and breast cancer in dogs. Spaying a female dog before their first heat virtually eliminates the risk of breast cancer later in life. However, if she is spayed after 2 years of age, spaying does not protect her at all. Similarly, a tumour known as a perianal adenoma (a tumour of the tissue around the anus) is much more common in male dogs that have not been castrated.
In people, there have been connections made between exposure to pesticides and the development of cancer. There does not appear to be as strong a link between environmental toxins and cancer in dogs, so this may not be such an important influence. It does appear that being exposed to cigarette smoke may increase the risk of cancer of the nose and sinuses. Sun damage can lead to skin cancer in dogs.
Responsible dog ownership and attention to your dog’s well being may not prevent him developing cancer but if you regularly give him a condition check when you are grooming or make a point to have a once weekly examination, you may be able to improve the outcome by catching the warning signs early. Other warning signs to look out for are included that you may see at any time.
CONDITION CHECK STEPS AND CANCER WARNING SIGNS
- Feel your dog’s body all over to check for any lumps and bumps. If you dog is longhaired, pay special attention to this. If you notice any lumps or bumps, then get them checked out by your veterinarian.
- Check your dog’s mouth for bad breath, bleeding gums. Does he seem sore? Monitor how he eats a treat or his meal, is he having difficulty swallowing. If he shows any of these signs, he should be checked over by your veterinarian.
- Most dog owners know what their dog is like when he is in fine fettle and bursting with play, health, and activity with a healthy appetite so it should be easy to see if he is depressed or just off colour. Any of these signs of unwellness or vomiting or lethargy should be investigated.
- Does your dog have any lumps and bumps on his leg joints? Is he lame or sore? If he is showing any of these signs, he needs to be checked over.
- Check your dog’s body condition and see if he has lost weight unexpectedly, if so he needs a trip to the veterinarian.
- Are there sores that do not seem to be healing or bleeding and discharge from any body openings?
- Is your dog reluctant to exercise or has a distinct loss of stamina?
- Is your dog showing signs of difficulty, breathing, urinating, or evacuating stools?
If your dog exhibits any of these signs or you notice any abnormalities in your dog during your condition check, make an appointment with your vet sooner rather than later. Cancer treatment in dogs usually has a better outcome if it is started early, so getting a quick diagnosis is crucial.
OTHER CANINE CANCER PREVENTATIVE MEASURES
- Spay your female dog before her first heat to prevent breast cancer if she is not breeding stock.
- Male dogs with undescended testicles should be neutered as the retained testicle often becomes cancerous.
- Dogs with thin skin and coats with a pale colour should not be allowed too much exposure to the sun to avoid skin cancer.
- Choose your pedigree dog with care and avoid breeds with a predisposition to cancer or try to buy from a parental line that does not have any incidences of cancer.
- Feed your dog a high-quality diet that uses human-grade ingredients and little to no preservatives or additives. Good nutrition is key to good health.
- Keep your dog at a healthy weight. Dogs that are overweight or obese are at greater risk of developing cancer.
- Try to limit your dog’s exposure to chemicals and pesticides such as lawn treatments and fertilizer, known to increase risk of cancer.
- Avoid chemical flea and tick treatments or limit the use to when you need them.
- Consider using natural remedies and treatments to support your dog’s immune system
CANINE CANCER TREATMENT TYPES
Radiation therapy involves using a focused radiation beam to kill tumour cells. Radiation can also affect rapidly dividing normal (good) cells, so veterinarians try to protect surrounding parts of the body as much as possible. They also spread out radiation treatments to allow normal cells to recover.
Chemotherapy is a drug treatment that may be a single drug or combination of drugs to aggressively treat the cancer. In general, dogs receive a lower dose than humans as it is important for dogs to retain basic functioning. This also helps them to avoid some side effects and tolerate the treatment more robustly.
The purpose of the drugs is to attack cells and prevent them from dividing or to damage the cell’s DNA. The chemotherapy drugs cannot differentiate between cancerous and non-cancerous cells so the immune system is compromised and side effects can occur. Side effects are not so much of an issue with dogs as they receive the chemotherapy in lower doses.
It is unlikely your dog will lose his hair as a human would, as they do not continually grow hair like humans. There may be a little thinning or change of texture though. Poodles and Old English Sheepdogs are at risk of losing their coats as they have coats that continually grow.
The removal of cancerous tumours and growths will be done under a general anaesthetic. Biopsies may just require a local anaesthetic.
Complete removal of the tumour may be possible or in the case where a tumour affects other organs, is close to or entwined in major blood vessels, a partial removal to de bulk the tumour will be performed.
Your dog will experience some pain and discomfort after surgery and will need nursing. He will likely have some form of pain relief. It is important to discuss the surgery with your veterinary surgeon so you know what the surgery is, if the dog will need feeding tubes fitted for post surgery and you will need to discuss the options if the veterinary surgeon discovers more masses or complications.
If all of the tumour is safely removed, your dog is still likely to require follow up with chemotherapy or radiation.
Alternative and Natural Therapies
Some dog owners like to use alternative and natural therapies to support treatment that is more conventional. Many vets now offer these services and natural remedies, and they may improve the outcome for some cancer patients.
There are some natural remedies and treatments that have proved highly effective in supporting conventional medicine
While your dog is undergoing the stressful procedures of surgery, radiation and chemotherapy treatment, there are things you can do to support him. Good nutrition is vital to keep up his energy levels. If his appetite is poor, he may need to be fed through a stomach tube. He may need fluids to stop him becoming dehydrated, and in most cases, he will definitely need pain relief.
It is perfectly fine to choose not to continue treatment or not to treat your dog that has cancer if the outcome is not promising or if you do not have the finances to treat him. All veterinarians will give you support to make your dog’s life comfortable and will help you when it comes to making the right decision for your pet.
You can provide palliative care for your dog at home with the help of your vet and do what you can to keep his quality of life strong for as long as possible.
Advances in veterinary care mean that dogs are living longer than in the past, and the incidence of cancer is naturally increasing as more dogs reach geriatric age. New diagnostic tests and treatment choices mean that the outcome for many cases of cancer in dogs is quite good. Work with your vet, choose your treatments carefully, and you will get the best outcome possible for both you and your dog.
Finally, do not overlook the importance of a good pet insurance policy. This will not necessarily reduce the risk of cancer, but it may make routine wellness exams and preventative care more affordable. If your dog should be diagnosed with cancer during the course of their life, it will help you to afford lifesaving cancer treatments to help your dog battle this disease. Pet insurance is an excellent way to protect yourself and your pet.