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Oncology

Hearing from your local vet that they have confirmed or highly suspect a tumour in your pet can be a very difficult time. Leave it to us to develop a care plan bespoke to your pet’s needs and your personal preferences, freeing you up to concentrate on enjoying more quality time together.

For some pets referred to us, the investigations will have been completed by your local vet and we then recommend the most effective treatments selecting from specialist surgery, radiation therapy, chemotherapy, immunotherapy, palliative care, and combinations of these. Some patients also benefit from the completion of investigations with us before starting therapy. These treatment options might sound scary to some pet owners, such as chemotherapy, but the experience is very different from human medicine and constantly improving- please click here to access a leaflet on this topic if this is a concern for you.

Your pet’s quality of life will be our top priority before, during, and after treatment as nothing is more important to us. Your pet can avail of most treatments as an outpatient, maximising their time at home, but if you’re busy during office hours, we can offer early admissions and evening discharges too. Although we can offer a genuine cure for selected tumours, for pets with other tumours we suggest monitoring after therapy, designed to confirm our enduring control of the disease and identify when further intervention is helpful.

Our Oncology Service was founded by Dr. Richard Elders, a Diplomate of the European College of Veterinary Medicine, and recognised by both the Royal Veterinary College and the European Board of Veterinary Specialisation as a specialist Oncologist for dogs and cats. Richard also has similar qualifications in Internal Medicine and a PhD in mast cell targeting and immunotherapy. He will see you and examine your pet personally, and is supported in the delivery of clinical excellence by his specialist colleagues in other disciplines, our devoted nurses and dedicated interns.

Like you Richard is a pet owner, and has previously been in the position in which you find yourself now. We’re ready for an in-person or remote consultation, arranged through your local vet, so both you and your pet can start to feel better.

  • Chemotherapy
  • Mast Cell Tumours
  • Lymphoma
  • Sarcomas
  • Apocrine gland of the anal sac adenocarcinomas
  • Feline injection site sarcomas
  • Osteosarcoma
  • Urothelial carcinoma

Chemotherapy

Chemotherapy is thankfully a very different experience in dogs and cats compared with chemotherapy in people. The medications used are often the same, but we use much lower doses. We use previous research to choose a dose which is effective against their tumour and should be easily tolerated by your pet.

Tumour cells usually reproduce more rapidly than most other normal tissues in the body. Most forms of chemotherapy medications work by damaging the DNA within reproducing cells, or other structures involved in reproduction. Rapid reproduction leads to chemotherapy causing greater damage in tumour cells than in normal tissue cells in which reproduction is typically slower. As the tumour cells try to reproduce, the chemotherapy induced damage can cause them to die off. This difference in sensitivity between tumour cells and normal tissue cells allows us to effectively treat tumours with minimal side effects in the rest of the body. Furthermore, normal tissue cells tend to repair themselves better than tumour cells.

Sometimes chemotherapy is used as the only therapy, such as with lymphoma. Sometimes we use surgery first to get rid of the bulk of a tumour, followed by chemotherapy to fight against any cells let behind locally or around the body (called “adjuvant” chemotherapy, such as with mast cell tumours, or osteosarcoma). Very occasionally we use chemotherapy before surgery (called “neo-adjunctive” chemotherapy such as with some mast cell tumours and injection site sarcomas).

There is no one size fits all approach, however, so depending largely on the tumour type diagnosed, Dr Elders will suggest which chemotherapy medications are most likely to be successful, based on previous research.

The vast majority of pets have treatment on an out-patient basis with an overnight stay being very rarely needed. The risk of side effects in your pet from chemotherapy medication is small but cannot be guaranteed to be zero. The majority of treated pets tolerate their treatment without any problem, due to the low doses used, validated by previous research. In the unlikely event of significant side effects, you pet would be welcome back here for further care on a 24 hour basis, and we can be contacted for advice at any time too. We will also discuss the risks of your exposure to chemotherapy residues before treatment starts and at each treatment visit.

Mast Cell Tumours

Mast cells are normal defensive immune system cells which help to get rid of parasites but are also the cell behind allergies, and they can become mutated and develop into tumours. A mast cell tumour is the most common skin-based tumour in dogs. Some breeds are especially prone such as breeds with a short nose, retrievers, Weimaraners, and Shar Pei. Most predisposed breeds tend to have more frequent but less aggressive mast cell tumours. Most dogs are older when they develop a mast cell tumour.

All mast cell tumours cause a problem in the local area. Reassuringly, the vast majority of dogs with a mast cell tumour in the skin or the fatty tissue underneath will have long term control or a cure achieved through surgery, and will not need any further therapy. A minority of mast cell tumours will try to spread/metastasise and will not be cured by surgery alone. To try to identify those which will benefit from further therapy, we look at several features.

Grade is an assessment of aggressiveness of the tumour cells made by microscopic examination. There are two methods of grading which separate the less aggressive from the more aggressive tumours which require more treatments.

Stage is an assessment of how extensive the disease is in your dog. We can use needle samples of the liver and spleen taken with ultrasound guidance to see if there is spread of the cancerous mast cells within. This is a very safe and minimally invasive procedure. However, a common place for cancerous mast cells to spread is the nearest lymph nodes. Needle samples are a good start in assessing the lymph nodes, but the best information comes from microscopic assessment of the whole node after its removal. Other tests can be offered for complete staging such as bone marrow sampling. Dr Elders will discuss with you how much staging is advisable, sometimes no staging tests are pursued.

After surgical removal, the tumour tissue is examined microscopically. This gives us the grade, and also an assessment of how much of a cushion of normal tissue has been removed around the tumour (the margin). If the margin is narrow, a second surgery or possibly radiation therapy might be offered to minimise the risk of recurrence. If the margin is adequate, the risk of recurrence is already minimised. Combining all of the above information, will determine if further treatment is likely to be beneficial.

If further therapy after surgery is advised, then you will be offered options including chemotherapy, medication to turn off growth signals (receptor tyrosine kinase inhibitors), and/or supportive medications. This might sound scary, but side effects are actually very unusual - please see our chemotherapy overview section for more details.

Finally, veterinary research is ongoing, and Dr Elders will be able to discuss any novel developments which might have occurred since this document was written, including new treatments such as immunotherapy.

Lymphoma

Lymphocytes are normal defensive immune system cells which travel around the body, with each one devoted to combatting a different virus, bacterium or parasite, together comprehensively protecting the whole body. If one of these cells mutates and becomes cancerous, then lymphoma is the most common resulting disease. Some breeds are predisposed, such as any breeds with a short nose, retrievers and Siamese cats. Most cats and dogs are older when they develop lymphoma. 

The best treatment for each individual cat or dog depends on a number of features.

Stage, is an assessment of how extensive the disease is. The location of the lymphoma is significant in terms of predicting spread, the symptoms that will arise, the overall outlook including lifespan, and therefore the treatment which is best in response. Sometimes all the mutated lymphoma cells are present in one location, such as in most cases of nasal lymphoma, meaning that radiation therapy of just the nose is a comprehensive therapy for them. However, just as healthy normal lymphocytes can travel around the body, lymphoma cells often are able to travel too, and some nasal lymphoma patients will be found to have lymphoma cells outside the nose, which results in chemotherapy being a more comprehensive treatment for them than radiation therapy. This might sound scary, but side effects are actually very unusual in cats- please see our chemotherapy overview section for more details.

Testing can be offered to look for the spread of lymphoma such as x-rays, ultrasound, needle samples of organs, maybe bone marrow sampling. Dr Elders will discuss with you how much testing is advisable, and sometimes no such tests are needed. Blood and urine samples can be useful both for assessing spread and to see the impact of the lymphoma on your cat, sometimes revealing features that need to be addressed promptly such as a high calcium level.

Grade is an assessment of aggressiveness of the tumour cells made by microscopic assessment. The size of the individual tumour cells can be seen on a needle sample, and size and the grade of the lymphoma are often aligned with large cells being associated with a high grade, aggressive lymphoma. However, grade is a more comprehensive assessment of the lymphoma cells than merely their size, and often requires a surgical biopsy of the lymphoma, perhaps with removal of a mass or a lymph node. Depending on where a tumour is, a biopsy through a scope might be another option.

Phenotype is a term which mainly describes the origin of the lymphocyte which has been mutated, such as B (for those originating in the bone marrow) or T (for those originating in the thymus). This information can be determined from any needle or biopsy sample of lymph node tissue. Flow cytometry is an antibody-based method of assessing needle samples, and provides the T or B status of a lymphoma as well as several other features of the phenotype which can impact the anticipated outlook for a dog or cat, and the best treatment choices.

If there is any confusion as to whether the problems in your dog might not be lymphoma but might actually be caused by a beneficial but excessive immune response, we can offer a PARR test. This test assesses the how related the cells are at the genetic level.

The aim of treatment in most cats and dogs is to significantly extend lifespan with a normal quality of life, through the least frequent visits.

Some clients prefer not to have chemotherapy and we can offer supportive medication to improve quality of life and lifespan without chemotherapy too. Finally, veterinary research is ongoing, and Dr Elders will be able to discuss any novel developments which might have occurred since this document was written, including new treatments and vaccines.

Sarcomas

Sarcomas are tumours which arise from mutation in any tissue which is not lining the insides or outside of the body and is also not a gland. They can arise from fat (lipoma), blood vessels (haemangiosarcoma), muscle (myosarcoma), etc. However, some mutated cells do not maintain the features of their origins, even after looking for them with sophisticated tests such as immunohistochemistry, in which case they are simply labelled soft tissue sarcomas. Although this might seem imprecise, soft tissue sarcomas are frequently diagnosed and well researched, so we know what to expect in terms of their threats and behaviour.

All soft tissue sarcomas have at least some potential to be malignant and spread around the body, none of them are truly benign. While all soft tissue sarcomas will have an effect in the local area, reassuringly, the vast majority of dogs with a soft tissue sarcoma will have long term control or a cure achieved through surgery, and will not need any further therapy. This is because only a small minority of soft tissue sarcomas will try to spread/metastasise. To try to identify those which will benefit from further therapy, we look at several features.

Grade is an assessment of aggressiveness of the tumour cells made by microscopic examination. This can be done through needle samples and biopsies.

Surgical removal of these is the most common treatment. After surgical removal, the tumour tissue is examined microscopically. This gives us the grade, and also an assessment of how much of a cushion of normal tissue has been removed around the tumour (the margin). If the margin is narrow, a second surgery or possibly radiation therapy might be offered to minimise the risk of recurrence. If the margin is adequate, the risk of recurrence is already minimised.

If further therapy after surgery is advised, then you will be offered options including standard chemotherapy, metronomic chemotherapy, and/or supportive medications, followed by a monitoring programme. For dogs who have surgery that does not remove all of the sarcoma cells with a good margin, we can recommend metronomic chemotherapy to combat the risk of recurrence. This is a very well-tolerated, home-administered form of low dose chemotherapy in pill form, and can also be used to retard the progression of sarcomas which are not removed through surgery. This might sound scary, but side effects are actually quite unusual- please see our chemotherapy overview section for more details.  

Combining all of the above information, will determine if further treatment is likely to be beneficial. If further therapy is unnecessary your dog will be offered a monitoring programme.

Finally, veterinary research is ongoing, and Dr Elders will be able to discuss any novel developments which might have occurred since this document was written, including new treatments such as immunotherapy.

Apocrine gland of the anal sac adenocarcinomas

Apocrine gland of the anal sac adenocarcinomas (abbreviated to AGASACas) are tumours which arise from mutation of the paired glands just inside the anus of dogs. Some breeds are especially prone such as Spaniels, typically in their later years.

Some AGASACa masses are small and found on relief of blockages in the rest of the anal gland, whereas, others become large and interfere with defaecation, sometimes narrowing or flattening the stool and causing discomfort. All AGASACa have some potential to be malignant and spread/metastasise around the body, and none of them are truly benign. Although many dogs will not have overt spread/metastasis at the time of diagnosis, this is present microscopically in the vast majority of dogs, and will emerge over time.

The best treatment for an individual dog with AGASACa depends on whether there is any evidence of spreading and how extensive the spread is, therefore we recommend a CT scan for the most detail to make these decisions. Spread/metastasis from an AGASACa can be to any organ, but classically will be to the local lymph nodes initially, making its way over time from the lymph nodes at the back of the abdomen to the front. The anal area mass and the local lymph nodes can be removed at the same time, but best how to approach this operation depends on the location, size and mobility of the lymph node, especially those in the pelvis. The results of a CT can suggest whether a surgical approach from behind, from in front of, or though the pelvis is best. Most large lymph nodes revealed on CT can be sampled using ultrasound guided needle samples which is a minimally invasive procedure. Some large lymph nodes will be inflamed or infected rather than having tumour cells within. If the lymph nodes are particularly large with tumour cells within, sometimes we substitute radiation therapy for surgery as the best first treatment option, and if there is unusually widespread disease we might suggest medical management over surgery. There is a limit to how small a mass can be detected by any type of scan, which means that some dogs with a clear set of results initially might have overt spread detected months or years later.

Surgery is the best treatment for most dogs with AGASACa. The majority of dogs will have the local lymph nodes removed. After surgical removal, the tumour tissue is examined microscopically to assess how much of a cushion of normal tissue has been removed around the tumour cells (the margin). If the margin is narrow, a second surgery or possibly radiation therapy might be offered to minimise the risk of recurrence. If the margin is adequate, the risk of recurrence is already minimised.

If further therapy after surgery is advised, then you will be offered options including chemotherapy, medication to turn off growth signals, and/or supportive medications, followed by a monitoring programme.

It might seem unusual that for a mass which is almost guaranteed to spread/metastasise that chemotherapy is not being emphasised. This is in part because the tumour cells are not usually reproducing rapidly and therefore do not take much of a hit from chemotherapy. In many past surveys traditional chemotherapy choices resulted in no benefit or only a small benefit in overall survival of groups of dogs with AGASACas.

Finally, veterinary research is ongoing, and Dr Elders will be able to discuss any novel developments which might have occurred since this document was written, including new treatments such as immunotherapy.

Feline injection site sarcomas

Feline injection site sarcomas are tumours which arise from mutations in tissue which have been injected in the past, often with a vaccine but other drugs and implants have caused sarcomas too. They seem to arise from an excessive immune system reaction to injections, which mutates over time into a very aggressive tumour which persists even after the injection has been absorbed. Tumour development was more common with historical vaccines, but still happens today including occasionally with non-vaccine injections, so some of the risk seems to be likely genetic, as most cats tolerate multiple injections without tumour formation.

Although feline injection site sarcomas have at least some potential to be malignant and spread around the body, few of them actually do spread/metastasise. Therefore, the major threat is from the local damage that the sarcoma causes. Injection site sarcomas are the most invasive type of sarcomas seen in cats, easily invading through local tissues including bone. While we treat most types of sarcomas by removing all tissue within 2-3 cm of the overtly abnormal mass, for injection site sarcomas, research has shown we need to remove 5 cm of tissue to achieve similar control. Having to remove such a large amount of tissue is quite routine for us, and will typically be followed by re-stretching of the skin over time, with comfort maintained throughout. Some injection site sarcomas are in challenging locations which can result in a compromise between removing the necessary amount of tissue for tumour control and the preservation of vital structures (e.g. nerve tissue).

To make as sure as possible that a surgery will have the desired effect, most cats have an initial CT scan to define in the best detail the most appropriate surgical approach.

Where we can predict that an injection site sarcoma is likely to recur even after extensive surgery, or where the microscopic analysis of a removed tumour confirms recurrence is likely, we can offer radiation therapy as well as surgery.

Where spread/metastasis is detected on a CT scan, or when other options are declined, we can offer either standard or metronomic chemotherapy, medication to turn off growth signals (receptor tyrosine kinase inhibitors), or palliative care. This might sound scary, but side effects are actually unusual - please see our chemotherapy overview section for more details.

Metronomic chemotherapy is a very well tolerated home-administered form of low dose chemotherapy in pill form and can also be used to try to retard the progression of sarcomas. Receptor tyrosine kinase inhibitors are growth factor inhibiting drugs which seek to oppose tumour cells dependant on these growth factors, given in a pill form at home every 2 or 3 days. At this point the evidence base for each of these medical options is quite weak when groups of cats are analysed, but individual cats can do well.

Osteosarcoma

Osteosarcoma is a malignant tumour which has developed from mutation of normal bone cells, often with a mixture of uncontrolled production and uncontrolled destruction of bone tissue. Osteosarcoma is the most common diagnosis for a mass in a bone, but other tumours and non-tumour conditions can be present too. Some breeds are predisposed, such as any tall and/or heavy breeds, especially Rottweilers, but also heavily physically-trained dogs and dogs which have had a previous fracture or implant in the bone. Many dogs are older when they develop an osteosarcoma, but there are also many cases around the time of skeletal maturity/achieving adult height.

There are a number of different diagnostic tools that we can use to get an accurate diagnosis, these include; radiographs, biopsies, blood sampling, urine sampling and CT scans.

Quality of life is our main focus at Hamilton Veterinary Specialists. Without doing any surgery, we can improve comfort and lameness through external supports, medications, and radiation therapy. There are several medications which relive pain and also reduce further weakening of the bone which can be used in combination for patients not having surgery or prior to surgery. Radiation therapy is primarily offered as a further option for pain relief too. These would be considered palliative care as they do not tackle the tumour directly.

Surgical treatment options include lump removal, amputation and limb sparing surgery. Sometimes chemotherapy will then be used post surgery. Chemotherapy might sound scary, but side effects are actually very unusual- please see our chemotherapy overview section for more details. There are a quite a few variations to the above treatment options. Dr Elders will guide you through all these options. After completion of your choice of treatments, your dog will be offered a monitoring programme.

Urothelial carcinoma

Urothelial carcinoma (previously called transitional cell carcinoma) is a tumour which arises from mutation of the normal cells lining the urinary tract (called urothelial or transitional epithelial cells). This is the most common bladder-based tumour in dogs, but can also effect the kidneys and the tubes that carry the urine (ureters and urethra). Some breeds are especially prone such as Spaniels and many Scottish breeds, most often in their later years.

The symptoms of a urothelial carcinoma are often the same as those for other bladder conditions like stones and infections. Some tumours are poorly structured and are prone to repeated infections making the underlying tumour more difficult to diagnose. There is a urine test based on a genetic change called a BRAF mutation which seems to be present only in cancerous urothelial cells. This allows the majority of urothelial carcinomas to be separated from other bladder conditions.

Other methods of making a diagnosis are mainly biopsy-based. There are several ways in which we can try to take a biopsy from the inside the urinary tract without crossing the skin (e.g. catheter-based, scope-based), which avoids the risk of spread. Very rarely is a surgical biopsy needed to reach a diagnosis.

Tumours arising at the front of the bladder can have a very good initial response to surgery. The majority of urothelial carcinoma arise at the back/trigone of the bladder, a more specialised area with a lot of vital anatomy nearby meaning beneficial surgery is typically impossible.

There are several treatments on offer, and Dr Elders will discuss the best approach with you. For a typical urothelial carcinoma at the back of the bladder, the most commonly chosen option is a medical combination consisting of chemotherapy and non-steroidal anti-inflammatory medications. Both medications are effective, and we can offer sole non-steroidal anti-inflammatory to clients wishing to avoid chemotherapy, however combination therapy is superior. If chemotherapy sounds scary, be reassured that side effects are actually quite rare- please see our chemotherapy overview section for more details.

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