Category: cancer-cats

Radiotherapy uses radiation (like a powerful type of X-rays) to damage and destroy cancer cells. The radiation can be administered in a number of ways but when it contacts cells it causes permanent damage. Most commonly radiation is delivered from an external source for a short period of time on a regular basis (external beam therapy). Radiation delivered in high doses can do damage very rapidly so a short exposure to the radiation beam will damage the cells which die off over the next few days.

The aim with radiotherapy is to give a high dose of radiation to the cancer cells (doing maximum damage) whilst minimising the dose to the rest of the body.

It is quite expensive to have radiotherapy and you will probably have to travel to a specialist centre to get treatment so your vet will not recommend the procedure unless they think it is likely to help in the treatment of your pet.

Cancers can be treated using surgery, drugs (chemotherapy), radiotherapy or often a combination of these. Each type of cancer is best treated in a particular way and if your vet has recommended one form of treatment it is likely that this is the best option for your pet. However, if you are concerned about the treatment then discuss your worries with your vet.

Radiotherapy is usually given as a course of treatments. It is very important that all treatments in the course are given at the right time so make sure before agreeing to treatment that you can take your pet for every session. The damage to cancer cells caused by radiotherapy builds up over time so each treatment kills off cells missed by the previous one. The time between each treatment in the course allows the normal healthy tissues to recover and grow. So the course maximises the damage to cancer cells whilst reducing the risk of side effects.

Many owners are worried by the idea of radiotherapy for their pet because they have heard of the side-effects suffered by human cancer patients. In people the aim of cancer treatment is to kill all cancer cells and cure disease doses of radiotherapy are therefore high and side-effects such as vomiting and hairloss are relatively common.

Although it does sometimes cure cancer, the aim of cancer treatment in pets is to prolong a good quality of life (rather than necessarily trying to cure the cancer). This means that treatment sessions are designed to have the maximum beneficial effect without causing severe side effects. Your pet should remain well throughout the course of treatment.

If your pet is having external beam radiotherapy the radiation does not stay in their body so they are able to come home between treatments. However, it is very important that the treatment is delivered at regular intervals and so if the treatment interval is short (e.g. alternate days) your vet may recommend that they stay in hospital so that you do not have to keep travelling back and forward.

It is essential that your pet remains still throughout the whole treatment as this must be directed at a very specific area of the body. Severe damage can be caused if the radiation beam strikes the wrong tissue during the procedure.

Modern anaesthetics are very safe and your pet will probably recover more rapidly from an anaesthetic than any form of sedation. As radiotherapy is usually performed at specialist centres it is likely that your pets anaesthetic will be monitored by a vet with a special interest in anaesthesia and the anaesthetic will be very safe. You will usually be able to take your pet home as soon as they have recovered from the anaesthetic unless they are receiving further treatment.

As your pet will be having an anaesthetic your vet will ask you not to feed your pet the evening before the day of the treatment. Occasionally drugs are given before treatment to increase the effect of the radiation on cancer cells if your vet gives you specific instructions make sure you follow them carefully.

There is a small risk associated with repeated anaesthetics, but your pet’s health will be closely monitored and modern anaesthetics are very safe.

Radiotherapy is a very powerful treatment and the aim is to give a dose that will destroy most of the cancer cells whilst allowing the normal tissue to recover between treatments. Some cells are very sensitive to the effects of radiation so when treatment is planned your vet will try to avoid particularly sensitive areas (such as the eye).

After treatment the area of skin around the tumour may become red or sore looking. Your vet will prescribe tablets if they are concerned about your pet, but if you are worried make sure you voice your concerns at your next visit. Long term problems are usually changes at the site of the treatment such as bald patches or white hair regrowing (where it should be coloured).

If your pet has had an anaesthetic they should be fully recovered by the time you get home. Offer a light meal at tea time but do not be alarmed if your pet does not want to eat until the following day. Often a course of radiotherapy is given after a cancer has been removed if your pet has stitches keep a close eye on these as the radiation treatment may delay healing and the wound could open up.

If your pet is receiving medication for other conditions check with your vet that you should continue these throughout the radiotherapy course.

Chemotherapy is a highly toxic drug given alone or in combination with other drugs to damage and destroy cancer cells. Chemotherapy drugs can kill all cells (healthy ones as well as cancer cells) and great care is necessary when using them. When treating lymphoma more than one type of chemotherapy is given at the same time the aim of this is to attack the cancer cells from two or more sides whilst minimising the amount of damage to normal tissue by using lower doses of each drug.

Doses are given at intervals (which may be days, weeks or months apart) and during the interval healthy tissue is able to recover and regenerate. Unfortunately in most cases the cancer cells also start to recover and over time the cancer cells often develop a resistance to the drug that is being used for treatment. Treatments must be given regularly so before agreeing to start treatment make sure you are able to give regular medication or can take your pet to hospital for regular treatment sessions as necessary.

There are many chemotherapy treatment plans (also known as protocols) that have been used for the management of lymphoma in dogs. The most commonly used include Cyclophosphamide, Vincristine (known as Oncovin) and Prednisolone. This is often called the COP protocol. Sometimes another drug, doxorubicin (also called Hydroxydaunorubicin or Adriamycin), is added and this is called a CHOP or COAP protocol.

Treatment for lymphoma is usually a combination of tablets given at home and hospital visits for your vet to administer some drugs intravenously (directly into the blood stream). Remember that all these drugs are toxic and must be handled carefully. Drugs should always be handled with gloves and must be given according to the schedule prescribed by your vet.

Obviously it is particularly important that these drugs are kept out of the reach of children and pregnant women should not be exposed to them. If you accidently give too many tablets in one dose or give the doses too close together you must contact your vet or veterinary oncologist immediately.

All chemotherapy drugs can cause side effects but these vary depending on the type of drug and the way it works.

Prednisolone

Prednisolone is a steroid but in cancer therapy it is given at very high doses initially. It would be usual for dogs receiving prednisolone to drink more than normal and hence wee more often! The drug given to otherwise healthy animals is a potent appetite stimulant. However dogs receiving chemotherapy may have a poor appetite due to the cancer or the other chemotherapy drugs and so excessive appetite may not be a problem.

Some dogs are more affected by high doses of steroids and may have muscle weakness and show excessive panting. Stomach ulceration is also a potential side effect of high doses of steroids and may cause blood in the vomit or in bowel movements.

Vincristine (Oncovin)

Side effects are rare following treatment with vincristine. The drug is given by your vet into the vein in the leg – if the drug leaks out of the vein it may cause damage and soreness around the site of injection. Weakness and neurological changes are reported by people receiving vincristine but these are rare in domestic pets.

Cyclophosphamide (Cytoxan/Endoxana)

Like many chemotherapy drugs cyclophosphamide can reduce production of white blood cells by the bone marrow, making your pet more prone to infection. This effect usually starts around 1 week after treatment has been given, and reaches its lowest point at 1014 days. The bone marrow should naturally recover and will usually have returned to normal function before the next dose of doxorubicin is due. Your vet will usually check blood samples regularly from your pet to ensure that the bone marrow is working properly.

You should contact your vet straight away if:

• Your pet has a high temperature (above 38.9°C / 102°F) – if your pet has a fever they will usually be quiet and unwilling to eat
• Your pet is unwell (even without a high temperature)

Nausea and vomiting have been reported but in most cases this is mild and usually resolves without any treatment.

Hair loss following chemotherapy is not common in dogs. However, poodles and old English sheepdogs may be more at risk. Certainly clipped areas may take longer to regrow if your pet is receiving chemotherapy.

The main problem with cyclophosphamide is the risk of a form of cystitis. This is caused by irritation of the bladder by the chemicals formed when the drug is broken down in the body. To try to prevent cystitis the drug should be given in the morning and the dog should be encouraged to empty their bladder before bedtime. If you see any blood in the urine or your dog shows any signs of cystitis (frequent urination, discomfort on urination, or frequent squatting or straining) do not give any more cyclophosphamide until you have spoken to your vet.

Doxorubicin

Doxorubicin may also affect bone marrow function and you should be alert for signs of infection or anaemia. Doxorubicin can also reduce the production of other cells from the marrow, e.g. platelets (which help the blood to clot). Call your vet if your pet has any unexplained bruising or bleeding, such as nosebleeds, blood spots or bleeding gums.

Nausea can occur within a few hours of treatment with doxorubicin but this can be effectively controlled with drugs. If your dog is reluctant to eat or vomits after treatment make sure your vet knows. If your pet vomits after treatment do not offer them anything more to eat for 12 hours and then offer them a small tempting snack. Ensure that water is available and encourage them to drink if possible. Dogs with diarrhoea should be allowed to eat as normal but if you are concerned or the diarrhoea continues for more than 24 hours call your vet for further advice.

Some dogs receiving doxorubicin are anorexic after treatment. This may be due to sores in the mouth or in some people the drug alters the taste of food and this may be unpleasant for some animals. Try feeding tempting small meals more frequently to encourage your dog to eat.

Hair loss can also occur after doxorubicin treatment but this is a rare complication and not of any clinical significance.

Lomustine (CCNU)

Lomustine can cause severe suppression of the bone marrow and regular monitoring of blood cell counts is important if your pet is receiving this.

Inappetence, vomiting and/or diarrhoea are also relatively common side effects but these can usually be controlled if the dose is tailored appropriately to the patient.

Many of the chemotherapy drugs have cumulative toxic effects (meaning that the effect of each dose builds up in the body).

Many of the drugs are processed or removed from the body by the liver or kidneys. Your vet may need to check liver and kidney function with regular blood tests, particularly if your pet is receiving drugs which can cause damage to these organs. Lomustine can cause liver damage and permanent bone marrow injury so long term monitoring by blood tests is required.

Doxorubicin can cause damage to the heart muscles and if your pet is receiving this you may be asked to take them for regular ultrasound scans of the heart.

Long term side effects of steroids are not uncommon but these are usually not a significant health risk. Skin may become thinner and darker in colour, hairloss is quite common and dogs may develop a pot-bellied appearance.

There are many different things that can cause swellings: bruising or fluid build-up, abscesses, things attached to the skin, e.g. ticks (small parasites which latch onto your pet and suck blood swelling as they do so), and of course cancers. If you find any unusual lump or swelling on your pet you should make an appointment for your vet to check it out. Although most lumps are harmless, some can be very dangerous if left untreated. The biggest concern for most people is whether their pet has cancer.

Cancers are divided into two groups:

• Benign: These lumps may grow bigger but do not spread elsewhere.
• Malignant: More aggressive lumps, which not only grow but also spread through the body and may affect organs such as lungs and liver.

Some benign growths can also cause problems if they continue to grow. Even fatty lumps can grow to a huge size and may cause problems due to their size, e.g. restricting leg movement or pressing on the airways and causing breathing problems. Malignant growths are obviously more worrying – they must be removed before they have spread elsewhere.

Even your vet probably won’t be able to tell whether the lump is cancer, or some other kind of swelling, just by looking at it. There are several things to look for which may help your vet decide whether a lump on your pet is likely to be benign or malignant:

• If the lump can be picked up in the fingers and moved around it is less likely to be aggressive. Malignant lumps often grow into the tissues beneath the skin and this makes them more difficult to remove.
• If the lump grows very quickly it can soon cause problems even if it does not spread. Removing a large lump is much more difficult and leaves a bigger wound so fast-growing lumps should be removed while they are still small.
• Malignant lumps often cause a reaction in the tissue around them – if any lump is red, painful when touched or is ulcerated or discharging then it should probably be removed.
• Some cancers produce substances that make animals unwell – if your pet has a lump and shows signs of illness e.g. sickness, depression or excessive drinking then mention this to your vet when he examines your pet.

If a lump has been present for a long time without causing any problems it is unlikely to suddenly turn nasty. However, all lumps should be monitored closely. Feel the lump once a month (if you feel it too often you will not notice if it is growing slowly), and keep a note of its size. Ask your vet to measure the lump each year at the time of vaccination and record if it is growing. If the lump changes in any way, i.e. starts to grow more quickly, is sore or discharging, make an appointment for your vet to check the lump again.

If you find a lump on your pet your vet will want to examine the lump to see if they think it is likely to cause a problem. They will also examine your pet to see if they are otherwise healthy or if there are any other growths elsewhere. Unfortunately it will not be possible to say for certain that a growth will never cause problems just by looking at it.

If your vet is concerned they will take some samples from the lump to try to find out what sort of lump it is. Sampling a lump can be as easy as putting a needle into it to collect a few cells or it may be necessary to take a piece of the lump under anaesthetic. These samples can be sent to a pathologist at a laboratory who will be able to tell your vet what kind of lump it is. Once your vet knows this they will be able to advise you on the best treatment for your pet.

In most cases, the only treatment needed for small growths is to remove them. However, if it is a type of cancer that could spread elsewhere your vet may want to make sure that there is no sign of spread and to do this they may need to take X-rays or perform an ultrasound examination. If your pet is old or unwell your vet may want to take a blood sample to check your pet is healthy enough to have an anaesthetic.

In human medicine, skin lumps are often removed by a doctor using a local anaesthetic. It is unusual for this to be done in veterinary medicine. It is very important that the whole of a cancer is removed to make sure that it does not regrow. Even if the lump appears very small it may be necessary to cut quite deeply to remove all of it.

It is important that your pet lies still during the procedure – if they jump or move the operation will be more difficult and dangerous. It is necessary to give patients a sedative to make sure they stay still and sedation is no safer than a well-monitored anaesthetic. Sedated patients may take many hours to recover whereas the effects of a short anaesthetic should wear off more quickly in most animals. If you are worried about treatment of your pet, mention your concerns to your vet who will be happy to discuss all the options with you.

Fatty lumps

Probably the most common lump found on dogs is a fatty lump (lipoma). These are more common in obese animals. These are benign cancers that rarely spread and are often quite slow growing. However, over many years they can become very large and may need to be removed because they cause physical problems.

Sebaceous cysts

Often seen in older animals – these are swellings filled with a creamy substance similar to toothpaste. They are often found in the middle of the back. Sometimes the swellings become red and sore but normally they do not cause any problems. Sebaceous cysts can be removed but removing one does not stop others from developing.

Mast cell tumours (cancer)

These are one of the most common types of lumps found in the skin. Mast cells tumours are a type of cancer that can take on many different appearances and can easily be confused with all sorts of other lumps. Some mast cell tumours are harmless and cause no problems, others are very nasty cancers. It is difficult to tell how a mast cell tumour will behave and they can turn from a benign cancer to a malignant one so all mast cell tumours should be removed.

Histiocytoma

These are button like lumps about 1 cm across found on the skin of young animals. The lump may look quite red and usually comes up very quickly. Often they will go away as rapidly as they appeared without any treatment.

Warts

Warts look like small tags of skin. They are more common in older animals. Often animals that have a wart will go on to develop many others. Sometimes warts bleed and may be irritating in which case they will need to be removed.

Mammary tumours (breast cancer)

Lumps in the mammary glands of female dogs are very common and account for nearly half of all cancers in bitches. Most of these are relatively harmless but some of the most aggressive types of cancer can also be found here. Mammary lumps in male animals are often very nasty. Surgical removal of all mammary lumps is advisable and in some cases removal of all mammary tissue (mastectomy) is also necessary. Before removing mammary lumps your vet will want to check your pet thoroughly to make sure that the cancer has not spread anywhere else.

The most important thing to remember is that most lumps, even cancers, can be cured if they are caught early enough – so always check with your vet if you find anything unusual on your pet. In most cases your vet will be able to reassure you.

Chemotherapy is a highly toxic drug given alone, or in combination with other drugs, to damage and destroy cancer cells. Chemotherapy drugs can kill all cells (healthy ones as well as cancer cells) and great care is necessary when using them. Many vets in practice will refer patients to specialist veterinary oncologists when chemotherapy is being considered.

All chemotherapy drugs are toxic and should not be taken unnecessarily. However, it is important to get the risks into proportion and not to be afraid of managing your pet at home. Whilst the drugs can cause many side effects these are usually seen with large doses or long term use.

If your pet is taking a tablet and you touch that tablet the amount on your hands is unlikely to cause you any side effects even if you put your fingers in your mouth. However, many of the cancer treating drugs can cause cells to mutate. It is essential that pregnant women do not come into contact with these drugs as damage can be done to the foetus. Drugs causing DNA mutations can also cause normal cells to become cancerous.

Some chemotherapy drugs are irritant and can cause reactions or allergies in the skin if touched.

Often you will be asked to give tablets to your pet at home. It is important the drugs are given at regular intervals according to set treatment plans (protocols). Before your pet starts on treatment your vet will need to be sure that you are able to give the drugs regularly and to follow instructions regarding their use.

If you are really concerned about giving treatment at home, share your concerns with your vet. It may be that there is an alternative treatment that your vet can administer for you. These will have to be given in the veterinary hospital and you will need to take your pet for regular treatment appointments.

Many of the drugs can be given with food. Your vet will advise you on the best time and method of giving the drugs. If you give the drug with food always handle them with gloves and put in a small amount of tasty food (that you can be sure your dog will want to eat) in a small dish.

Watch your dog to make sure they eat the food and all of the tablets and then make sure that they do not spit the tablet out again afterwards. The bowl can then be washed up separately before giving your dog the rest of his food.

If you are doubtful whether your pet can be relied on to eat the tablets with food it may be safer to put the tablets straight down the throat. If you do this it is even more important to wear gloves as the protective coating put on some tablets can be dissolved by saliva in your dog’s mouth. If you have not given tablets to your pet before ask your vet to show you how to do this safely and effectively.

Your vet will not allow your pet to go home with you if there are any risks to you from your dog. It is perfectly safe to continue to treat your pet as part of the family and hugging and petting are all permitted. The risks to you come from exposure to the drug itself. Remember also that the drugs are removed from the body in urine and faeces so there is a potential second risk of exposure.

There is some debate over how long pets can excrete chemotherapy drugs and metabolites in their urine and faeces. Therefore it is sensible to avoid direct contact with waste from your pet while they are receiving chemotherapy.

Once a treatment course has finished, you should maintain the same strict measures that you followed during treatment for a further three weeks. If your dog is having tablets or capsules there may be a risk of exposure to the drugs in these if your dog vomits after treatment. Ensure that you wear protective gloves to clear up any vomit and place all the cloths used for cleaning and gloves in a tied plastic bag with the vomit and place straight in an outside dustbin.

Chemotherapy is the use of drugs to damage and destroy cancer cells. Chemotherapy drugs can kill all cells (healthy ones as well as cancer cells) and great care is necessary when using them. There are many types of chemotherapy and depending on the drug they can be given by mouth, directly onto the lesion or given by injection into a body space or directly into the blood stream.

Different chemotherapy drugs are more effective against specific types of cancer and it is essential to get an accurate diagnosis of the type of cancer before the appropriate drug can be selected for treatment. Many vets in practice will refer patients to specialist veterinary oncologists when chemotherapy is being considered.

Chemotherapy is just a highly toxic drug given alone or in combination with other drugs. Your vet will try to find a treatment that is particularly toxic to a given type of cancer cell but less so to normal healthy body tissue.

Chemotherapy is given at a dose that will kill as many cancer cells as possible without doing too much damage to normal tissue. Doses are given at intervals (which may be days, weeks or months apart) and during the interval healthy tissue is able to recover and regenerate. Unfortunately in most cases the cancer cells also start to recover and over time the cancer cells often develop a resistance to the drug that is being used for treatment.

Often more than one type of chemotherapy is given at the same time – the aim of this is to attack the cancer cells from two or more sides whilst minimising the amount of damage to normal tissue by using lower doses of each drug.

Cancers can be treated using a variety of therapies (surgery, radiation or chemotherapy) and often a combination of treatments is given. If your vet has recommended chemotherapy it will be because it is the most effective treatment for your pet. You may need to travel to a specialist oncology centre for treatment and some forms of chemotherapy are expensive, therefore it is important that you discuss all your concerns with your vet before treatment starts.

It is very important that if you begin a course of treatment that you are able to see it through to the end. Treatments must be given regularly so before agreeing to start treatment make sure you are able to give regular medication or can take your pet to hospital for regular treatment sessions as necessary.

In some cases you may be given tablets to give your pet at home. Remember that these drugs are potentially toxic and must be handled according to the instructions given by your vet. Drugs should always be handled with gloves and must be given according to the schedule prescribed by your vet. Obviously it is particularly important that these drugs are kept out of the reach of children and pregnant women should not be exposed to them. Other drugs have to be given by your vet in the veterinary hospital and you will need to take your pet for regular treatment appointments.

Chemotherapy protocols are carefully designed to maximise the beneficial effect and minimise side effects of the drugs. The drugs are given regularly with an interval that allows healthy tissue to recover between doses. It is therefore important that doses are not given too close together or too much damage can be done to healthy tissues. If you accidently give too many tablets in one dose or give the doses too close together you must contact your vet or veterinary oncologist immediately.

Everyone has heard stories of how unwell some people are whilst receiving chemotherapy and no-one wants this for their pet. However, there is a difference between human and veterinary medicine. In human medicine doctors are aiming to prolong life for as long as possible – this means that treatment in people is often very aggressive (high doses of drugs are used to kill the maximum numbers of cancer cells). The high dose of drugs used makes the side effects much worse. In veterinary medicine vets are trying to prolong only high quality life. In general doses of treatment are calculated to minimise any ill effects experienced by your pet.

All chemotherapy drugs can cause side effects but these vary depending on the type of drug and the way it works. Hair loss, a well-recognised (and much feared) problem in people, is rare in animals receiving chemotherapy. However, clipped hair may take longer to regrow and the texture of the hair coat may change. Many dogs receiving chemotherapy will be given steroids as well; these typically have side effects of increased drinking and urinating.

Commonly, chemotherapy can cause damage to the bone marrow which may make animals anaemic or suppress their immune response. For this reason pets receiving chemotherapy are usually closely monitored with regular blood tests to monitor levels of blood cells.

Digestive system upsets (nausea with or without vomiting and diarrhoea) are caused by damage to cells lining the intestine. Effects can range from extremely mild diarrhoea to severe vomiting and bloody diarrhoea. In most cases these complications are short lived and can be managed quite simply with the use of drugs to control sickness. However it is very important to report such complications to your vet so that they can provide you with additional treatment and it may be necessary to reduce the dose of the chemotherapy to prevent these complications occurring after the next dose.

If you are concerned in any way about your dog’s health you should contact your vet immediately.

Many of the chemotherapy drugs have cumulative toxic effects (meaning that the effect of each dose builds up in the body). Many of the drugs are processed or removed from the body by the liver or kidneys. Your vet may need to check liver and kidney function with regular blood tests, particularly if your pet is receiving drugs which can cause damage to these organs. One commonly used chemotherapy drug can cause damage to the heart muscles and if your pet is receiving this you may be asked to take them for regular ultrasound scans of the heart.

Osteosarcoma is most commonly found in large or giant breeds of dog and it is well known that certain dog breeds develop this cancer more often than others. It is frequently seen in rottweilers and Irish wolfhounds in particular.

Osteosarcoma of the limb bones can be extremely painful and the typical presenting complaint for affected dogs is that of an intermittent lameness. The lameness may respond to standard doses of pain-killers initially but rarely for more than a week or so. Sometimes a swelling in the bone at the site of the cancer may be noted and this is often painful, red and hot to the touch.

If your vet suspects that your pet has a bone cancer they will first want to take X-rays of the affected site. Whilst osteosarcoma cannot be definitively diagnosed on an X-ray alone, a presumptive diagnosis can be made and in many cases biopsy is not necessary. In addition X-rays of the lungs are obtained to see if the cancer has spread. If there are any other painful bone lesions these should be investigated. If your vet detects any enlarged lymph nodes in the region of the bone lesion samples can be taken using a needle and syringe to collect a few cells for examination.

While the most pressing concern in patients with osteosarcoma is undoubtedly the pain associated with the bone cancer, it is also important to be acutely aware of the fact that osteosarcoma in dogs spreads rapidly via the blood stream. Therefore any treatment plan needs to address the secondary spread of the cancer as well as the bone cancer itself. Therefore management of osteosarcoma in dogs focuses on both the primary and the secondary tumours.

Treatment: primary tumour

The ideal therapy involves complete resection of the bone cancer and this most often requires limb amputation. Many dogs cope extraordinarily well following amputation but clearly there are some patients for whom this would be inappropriate. Concurrent neurological problems or severe arthritis are reasons for not considering amputation. Moderate arthritis can be managed extremely well with suitable medication and need not be a reason for rejecting amputation; obviously this should be evaluated on a case by case basis. Amputation invariably has a tremendous impact on the state of mind of the patient. While it is clearly a major operation, these patients seem to be so relieved to be free from the pain that they recover extremely quickly.

In the event that amputation is considered inappropriate there are other options. For osteosarcomas of the distal radius (this is the lower front limb just above the wrist joint equivalent in dogs) an operation can be performed in which the affected piece of bone is removed and replaced by a special implant. This procedure, called limb-conserving surgery, can restore the dog to normal mobility in a very short time. While this approach carries a definite appeal, it is critical to emphasise that the degree of cancer control afforded by this approach can at best be equivalent to amputation. Following this treatment there is also a risk of the cancer returning in the same bone at some point. More importantly, this procedure is associated with a high risk of complications, worst of which is infection associated with the metal implants.

For the patients in which amputation and the so-called limb-conserving surgery are not appropriate, palliative therapy can be administered in the form of radiotherapy (weekly on 3 out of 4 weeks) and chemotherapy in conjunction with the first and final doses of radiation. Other radiotherapy treatment protocols are described and this is an active area of research so it would pay to consult an oncologist if further detail is required.

A further novel therapeutic approach is the use of a drug that is very highly concentrated in active bone tissue, as one finds in osteosarcoma. At the high drug concentrations achieved in a bone cancer the drug is supposed to become toxic, specifically targeting the nearby cells which are of course cancerous ones. In practice, this approach has failed to achieve the results that were initially promised. There remain isolated cases that exhibit tremendous responses so this treatment option should not be rejected completely. It may be that further refinements to the treatment plan in the future result in improved cancer control.

Treatment: Secondary Spread

Sadly, despite control of the original cancer, it is the development of metastatic cancer (that has spread elsewhere in the body) that leads to euthanasia of many patients with osteosarcoma. Optimal outcomes are achieved by treating both the primary and the secondary cancers. In order to treat all the sites to which the cancer may spread it is necessary to give chemotherapy. As a rule this treatment is tolerated extremely well. The most widely used chemotherapy protocol involves treatment once every three weeks for a total of four doses.

Over the last few years veterinary oncologists have tested novel combinations of chemotherapy agents for the management of secondary cancer in osteosarcoma. Despite increasing levels of side effects, there remains no good evidence of an improvement in outcome associated with these treatment protocols. With the constant emphasis on quality of life, most oncologists choose to use chemotherapy aiming for reduced side effects whilst maintaining the same beneficial results in terms of cancer control and overall survival. In most cases, chemotherapy treatment passes uneventfully. All owners must be fully apprised of the risks of chemotherapy administration prior to embarking on a course of treatment.

Following diagnosis, life expectancy can be summarised as follows:

• Without therapy the average survival time is approximately 2 months. This is primarily determined by the discomfort associated with the primary cancer.
• If amputation is performed the average survival time is increased to 6½ months with a few patients alive after 2 years.
• Patients receiving palliative radiation and chemotherapy have an average life expectancy of six months.
• Amputation (or limb-conserving surgery) with chemotherapy makes the average survival time just a little less than one year with 2 in 10 dogs still enjoying a good quality of life 2 years after surgery.

Not all of the treatment options outlined are suitable for all patients. While it is important for owners to be aware of the options and the reasons for choosing one treatment over another, the ultimate decision about which treatment plan is most appropriate is best made in conjunction with the veterinary oncologist.

Lymphoma is a cancer of the white blood cells (lymph cells) and can arise almost anywhere in the body. Although it is always frightening to learn that your pet has cancer, lymphoma is one of the most commonly treated forms of the disease.

Lymphoma in dogs can present in many different ways. The most common is for a dog to develop large swellings in areas where lymph nodes are found. The most prominent of these is under the back of the jawbone on either side. Typically these swellings will suddenly appear and can measure up to 2 cm or 1 inch or more. They often feel firm but are mobile under the skin if you manipulate them.

Your vet will first want to examine your dog. They may be able to feel enlarged lymph nodes on your dogs body. Chest X-rays or ultrasound may be needed to identify the presence of tumours in the chest or abdomen.

Diagnosis is made by taking a sample of the tumour tissue for examination. This can be done using a fine needle aspirate, core biopsy or surgical biopsy. A sample of the tissues affected can be examined under a microscope.

Some types of lymphoma are associated with high blood calcium concentrations (hypercalcaemia). It is important for the well-being of the patient that complications like this are identified and managed appropriately.

Sadly chemotherapy will not cure lymphoma. However the disease will go in to complete remission in up to 85 out of 100 dogs treated with a standard chemotherapy protocol. A remission means that the disease improves and clinical signs are reduced a complete remission means that it appears that the disease has completely resolved and your pet will show no signs of illness at all. The duration of this remission is variable; a few cases may survive for years but usually patients will survive somewhere between 2 and 6 months. On relapse of the disease, it is often appropriate to consider alternative therapy to attempt to regain control over the tumour.

Those animals that experience a complete remission of their disease have a better chance of longer term survival. Sometimes it is appropriate to repeat treatment with the same protocol they had before if this produced acomplete remission in the first place. In other cases it is more appropriate to employ a new rescue protocol. Chemotherapy rescue may be something that requires referral to a specialist oncology centre.

In dogs, the life expectancy with most types of lymphoma without treatment is limited to only a few months. If chemotherapy is given, life-expectancy increases to an average of 6½ to 12 months depending on the treatment plan. The average life expectancy on COP protocols is approximately 6½ months. The CHOP protocols achieve complete remission in a higher percentage of cases and the average life expectancy is improved as a consequence to approximately 1 year.

It is tremendously important to emphasise that patients undergoing chemotherapy (or any other cancer therapy for that matter) do so because their team of carers, the primary veterinary surgeon, the veterinary oncologist and the family at home, all feel that the treatment is improving quality of life at all times. Chemotherapy and cancer rightly carry a certain stigma. Your vet should take great pains to ensure that any potential side effects are discussed fully prior to embarking on a course of cancer therapy. This way you can make informed decisions about the treatment choices for your pet. The aim of cancer treatment in pets is to promote a good quality of life first and foremost and life expectancy second.

An insulinoma is a special kind of cancer of the pancreas. These cause symptoms by producing excessive amounts of insulin, which results in the animal suffering low blood sugar levels and feeling light-headed and weak. Animals with insulinomas can also show symptoms such as reduced ability or enthusiasm to exercise and even fainting, particularly after long periods without eating.

Insulinomas can be very challenging to diagnose because:

• The symptoms are not specific to this condition, and
• Blood tests might suggest there is a relative imbalance between insulin and blood glucose but are rarely conclusive.

If your vet suspects that your pet may have an insulinoma on the basis of the symptoms it shows they will need to take some blood tests to confirm exactly what is going on. It is also important to check for evidence of spread of the cancer using abdominal ultrasound and chest X-rays.

Ultimately the diagnosis is made by surgical biopsy but clearly your vet needs to be confident of what they would find in order to perform this operation. Oddly, insulinoma is diagnosed much more frequently in the summer; in one study 9 out of 10 insulinoma cases treated over the course of a 5 year period were diagnosed between May and September!

Patients with insulinoma are treated according to the severity of their problem. In animals where there is an apparently solitary lump in the pancreas, surgery can be performed to remove the part of the pancreas containing the cancer.

If the cancer has already spread to the lymph nodes or the liver, surgery is unlikely to have a beneficial effect and so treatment is aimed at controlling the signs of disease with medication. Patients who are not good surgical candidates receive medical therapy, initially solely with a kind of steroid called prednisolone.

Life expectancy following a diagnosis of insulinoma is related to how badly affected the individual is. If surgery has been performed the development of post-operative complications might significantly influence life expectancy.

Previous reports in the literature describe average life expectancies of approximately 1 year for patients undergoing surgery and 2½ months for medical management. A more recent UK study reported outcomes that appeared to be significantly improved by comparison, with an average life expectancy following surgery of approximately 18 months. For patients who have achieved normal blood glucose control post-operatively, the average survival time was in excess of 3½ years. This compares reasonably favourably with published estimates of up to 381 days.

It should also be remembered that patients receiving medical therapy, whether due to disease relapse after surgery or because surgery was not an option, can still enjoy a prolonged period of normal life. The average life expectancy for these patients in the UK study was 15 months from the time of institution of medical therapy.

Mast cell tumours arise from a special type of cell that typically lives in the skin. These cells are normally involved in inflammatory reactions. Therefore, mast cell tumours can show any of the changes typically associated with inflammation like swelling and redness. In fact, it is common for owners to notice that the lump of a mast cell tumour has been fluctuating in size.

There is a marked variation in the behaviour of mast cell tumours and for this reason a tumour grading scheme is used. This scheme categorises mast cell tumours into three groups usually described as grades 1-3; sometimes the terms well-differentiated, intermediately differentiated and poorly differentiated are used.

The tumour grade significantly influences the treatment decision-making process. The higher grade a tumour is, the more likely it is to infiltrate into the normal looking body tissues around the tumour and the more likely it is to spread through the body via the blood or lymph systems.

Many of these tumours can be cured but only by appropriate intervention and there is great merit in finding out what grade a mast cell tumour is before definitive treatment is planned.

Mast cell tumours do not have a typical appearance and so any lump in or under the skin should be viewed with suspicion as it could be one. High grade mast cell tumours tend to look bad from the start. They can be big, red and frequently discharging serum or blood with no apparent border between the normal and the cancerous tissues.

Diagnosis is typically made by fine needle aspirate. This allows the collection of a small number of cells from a lump that can then be examined under a microscope. Sedation is rarely required and certain tumours, including most mast cell tumours, are very readily identified by this means.

Once a mast cell tumour has been diagnosed a complex series of decisions needs to be made. Ideally the grade of the tumour is determined first. This requires a biopsy to be obtained and submitted to a pathology laboratory.

Sometimes mast cell tumours are not identified until after surgery (to remove what had appeared to be an innocuous skin lump). The pathology laboratory describes the presence of a mast cell tumour and they will usually define the tumour grade and comment on the degree of invasiveness of the tumour. Under these circumstances further treatment is often necessary as the surgery has rarely been adequate to completely remove the cancer.

In the initial assessment of any patient with a lump that is considered likely to be cancerous, the local lymph nodes are examined by palpation. If they are enlarged, samples need to be obtained to determine whether there is evidence of tumour spread.

Low grade mast cell tumours can be cured in almost all cases. Surgical removal with appropriate margins of apparently normal tissue (1cm) is appropriate.

Intermediate grade tumours require wider margins (2-3cm). It is important to note though that approximately 1 or 2 out of 10 of these patients have spread of their tumour before the diagnosis is made. There is little point in successful removal of a single lump in the skin if cancer is left behind in other parts of the body.

Surgical removal of high grade tumours requires much wider margins of normal tissue to be removed. Approximately 8 of every 10 of these tumours have spread before the time of diagnosis and therefore the role of surgery in their management is limited.

Other treatments do exist for mast cell tumours. As a rule, they are less effective than surgery in that they do not cure the disease. However, there are instances when these treatments are more appropriate.

Radiotherapy

Radiotherapy or radiation therapy has a particular role to play in the management of mast cell tumours at sites that are not amenable to surgery, for instance the lower limb or around the face. Radiotherapy can dramatically affect the further progression of mast cell tumours, irrespective of tumour grade, with many cases failing to worsen for many months or even years after treatment. For this reason radiotherapy is also used in the post-operative management of some mast cell tumours, when there is a strong suspicion of incomplete removal.

By and large the side effects of radiotherapy are minimal; this is defined in part by the particular radiotherapy protocol used. Some animals develop reddening of the skin; others can develop skin ulceration. Skin related side effects can be irritating but tend to be short-lived. More serious effects can develop in the long term and for this reason radiotherapy is undertaken less freely in younger patients.

Chemotherapy

While there are countless descriptions of the use of chemotherapy in the management of canine cutaneous mast cell tumours in the veterinary literature, many of the successes reported have probably failed to recognise that a number of the cases described were already cured by the earlier administration of appropriate surgery. As a result, the stated responses to chemotherapy are likely to be overoptimistic. Having said that, chemotherapy may be appropriate in the management of metastatic mast cell tumours and some very favourable results can be seen.

Unfortunately, the response to chemotherapy can be unpredictable. While every effort is made to control the patients disease, it is not controlled at the expense of quality of life. The overriding philosophy in the management of all canine and feline cancer patients is the promotion of quality of life first and length of life second.

Designer drugs

2009 saw the arrival of the first veterinary designer drug, masitinib. This drug comprises a molecule which is specifically designed to block an enzyme important in the development of a proportion of canine mast cell tumours. Initial reports of its use are very encouraging.

The risks associated with the use of masitinib are limited. In trials a low percentage of cases developed haemolytic anaemia, reason unknown. A relatively high proportion developed low grade gastrointestinal signs (vomiting and diarrhoea) that rarely required treatment modification. Current data suggest that the best indication for masitinib is high grade metastatic or multifocal mast cell tumours.

Complete removal of a mast cell tumour that has not spread from its original site will result in a cure. This is the case for nearly all grade 1 or low grade mast cell tumours and more than three-quarters of grade 2 or intermediate grade tumours. Unfortunately in the majority of cases with grade 3 or high grade tumours this is not possible.

In cases with high grade tumours or cancer that has spread, it is unusual that patients live more than six months from the time of diagnosis, even with treatment. We may find that this changes as we gain more experience with the new designer drugs. A specialist veterinary oncologist would be able to offer the most up to date information in this respect.

As with human cancers, the causes of cancer in dogs are still not well understood. Possible causes include:

• Toxic chemicals or exposure to harmful radiation.
• Abnormalities in the immune system that usually protects against infectious diseases.
• Abnormal genes.

The signs of cancer are very variable and depend on the type of tissue cells involved, the site of the cancer and the stage of the disease. Animals with advanced cancers often show weight loss and loss of appetite. If your dog has cancer it may be depressed, vomit, have diarrhoea or constipation or fever. Your dog may also get tired easily because of other effects caused by the cancer, e.g. anaemia. Cancer can occur in any animal and at any age, but certain types of dog are more likely to get certain forms of cancer.

Yes, most forms of cancer can be treated, but this depends on the type of cancer involved and whether the disease has spread. The outcome of treatment can be very variable. In some cases treatment can produce a complete cure, or at least significantly increase the length or improve the quality of your dog’s life. Sometimes euthanasia is the only humane alternative to a slow and painful death.

There are three basic options for treating cancers; not all are appropriate for every case and sometimes a combination of treatments has the best chance of success. The treatment options are:

Surgical removal

Usually the best choice for most cancers of solid tissue. If the cancer is relatively benign, or if a more malignant cancer has not yet spread to other parts of the body, surgical removal often produces very good results.

Chemotherapy (drug treatment)

Chemotherapy is the best option for cancers affecting the blood or multiple areas of the body. Drug treatment may also prevent or delay the appearance of secondary tumours in other organs after surgical removal of the original lump. Chemotherapy is used to improve quality of life in pets and the side-effects of chemotherapy seen in people are usually not seen in dogs.

Radiotherapy (x-rays)

Radiotherapy is often effective when tests have clearly shown the extent and size of the tumour. The radiation is usually delivered by a special machine in a radiotherapy unit. A beam of radiation is most effective on cancers of the extremities (such as the limbs and head) where it is less likely to damage normal tissue before reaching the tumour.

Radiotherapy units are only located in a few specialised centres and your vet would need to refer you to a cancer specialist for this form of treatment. In some cases it may be possible to treat the cancer by injecting radioactive material into the body.

Discomfort can be severe when the cancer is advanced but most cancer-related pain can be controlled. Your vet will probably try a gentle painkiller at first and move on to more powerful drugs if these are required. Your vet will try to improve your dog’s quality of life rather than prolonging the life of your dog if it is suffering.

Careful attention to your dog’s diet may improve its quality of life. Dogs need extra food to cope with the effects of a fast growing tumour but many cancer patients have a poor appetite and so lose weight. Warming the food or feeding by hand may help stimulate your dog to eat. There are also special diets designed for animals with cancer that provide good nutrition even if your dog’s appetite is poor.

This is the question that every owner wants answered but, as with human cancer, it is impossible for your vet to give you an answer with any confidence. The survival chances will depend not only on the type and stage of the disease but also on your dog’s general state of health. You should discuss this issue with your own vet so that you can agree between you an appropriate treatment plan for your dog.

It is understandable that, faced with a diagnosis of cancer, you will feel frightened about the future for your pet. Discussing your fears with your vet is the very best way to obtain reassurance and an independent assessment that you are doing what is right for your pet.