ABSTRACT: Lymphoma is the most common canine malignancy. Around 80% of dogs present with multi-centric disease that is characterised by enlarged peripheral lymph nodes. However, any organ system can be affected, so presenting clinical signs can be extremely varied. Many factors affect long-term prognosis, so early diagnosis and treatment is important. The treatment of choice is chemotherapy and this is usually an outpatient treatment. Some patients require hospitalisation either because of the extent of disease or because of complications from treatment. This article discusses the importance of recognising patients that require extra care and the role of nursing the patient with lymphoma.

Canine lymphoma is the most commonly diagnosed malignancy in dogs. Although the aetiology of the condition is unknown, a number of breeds are over represented – for example, the bull mastiff and golden retrievers.

Clinical signs and diagnosis

These can be very variable and nonspecific depending on the location. The most common presentation is multi-centric disease and this accounts for 80 per cent of all canine lymphoma. Multi-centric disease is characterised by peripheral lymphadenopathy and, although the lymph nodes are enlarged, the dog may appear to be perfectly normal at home.

Other clinical signs that are often seen include: anorexia, lethargy, weight loss, vomiting, diarrhoea, polyuria and polydipsia. In some cases, the presenting clinical signs may include dyspnoea, bleeding – or even less frequendy – seizures.

It is important to fully evaluate the patient with lymphoma, but the actual diagnostic route will depend on the presenting clinical signs. For dogs with peripheral lymphadenopathy, the typical diagnostic panel would include full blood work, thoracic radiographs, abdominal ultrasound and either a lymph node biopsy for histology and immuno- phenotyping or fine-needle aspirates submitted for immunocytochemistry.

Multiple factors affect prognosis and these include substage (a) where the dog is clinically well and substage (b) in which the dog is clinically unwell.

A patient in substage (a) has a better prognosis than one in substage (b). This is why you should never wait to start treatment on a patient with lymphoma as they can go from substage (a) to (b) very quickly – and progression to substage (b) will impact negatively on overall survival time, in addition to increasing the possibility of the patient becoming sick when started on chemotherapy.

Histological grade of malignancy

Cases showing ‘high grade’ histology respond quickly to chemotherapy but may rapidly develop resistance leading to a short remission; whereas ‘low grade’ cases respond slowly and so may take longer to achieve remission, although they may have a better overall prognosis. Dogs with B-cell lymphoma have a better overall prognosis too.

Presence of paraneoplastic syndromes

A paraneoplastic syndrome is the consequence of the presence of the cancer in the body, but is not the direct result of the local presence of cancer cells. Those occurring in cases of canine lymphoma include:

•   thrombocytopenia (the most common paraneoplastic syndrome)

•   immune-mediated haemolytic anaemia

•   anaemia of chronic disease-usually mild

•   hypercalcaemia (usually associated with T-cell lymphomas)

•   neutropenia (rare).

Response to therapy

Establishment of a complete remission is important. Approximately 80 per cent of patients do achieve this, but unfortunately a small percentage of dogs will have multi-drug resistance from the outset. If a patient does not respond to the initial protocol, another protocol should be implemented. There is no point in continuing to administer a drug that is obviously not working.

Treatment

Treatment for most patients means chemotherapy. In a small number of cases, radiation may form part of the treatment plan, and very occasionally, for isolated lymphomas, surgery may be the treatment of choice.

Doxorubicin-based protocols have a survival advantage in most patients with lymphoma and are considered the ‘gold’ standard. In some cases, where the lymphoma is more indolent in nature, then other protocols that do not include doxorubicin may be indicated.

Side effects from treatment can result from the toxicity of the drugs themselves and also from the effects of the tumour on the patient. It is very important to distinguish between the two.

Whatever protocol is selected will involve a combination of drugs that have the potential to result in side effects. A small number of dogs will lose hair, for example, Bichon Frise (Figure 1). Some of these side effects are the same as the clinical signs caused by the lymphoma, such as vomiting, diarrhoea and inappetence.

Figure 1: A small number of dogs will lose hair

Many patients can be treated as outpatients, but in some cases hospitalisation is required. Patients that require additional support include those with a high tumour burden, or if a major organ is affected, such as the liver or kidney. Staged induction, reduced doses, anti-emetics, and intravenous fluid support need to be considered in these patients.

In dogs with large tumour burdens that respond well to treatment, the concern is the development of Tumour Lysis Syndrome. This syndrome is well documented in the human literature and probably occurs with greater frequency in veterinary oncology than is appreciated. The most distinctive abnormality seen on blood work is hyperkalaemia – clinical signs include lethargy, fever, collapse, vomiting. Treatment is based on aggressive fluid therapy and correcting electrolyte abnormalities.

Nursing the sick’ lymphoma patient

Why might a patient with lymphoma become ill (Figure 2)?

Figure 2: Canine lymphoma cases demand attentive nursing

1.   The disease itself

•   Location-involvement of major organ systems – the icteric dog with liver failure secondary to hepatic lymphoma, paralysis with spinal disease, persistent vomiting from intestinal lymphoma.

•   Extent – huge submandibular lymph nodes causing oedema and difficulty in breathing, huge mediastinal lymphoma resulting in respiratory distress.

•   Paraneoplastic syndromes – severe hypercalcaemia resulting in renal failure, anaemia.

2.   Response to treatment

•   Tumour burden – if the patient has a significant amount of disease and responds well to induction chemotherapy, t
he death of a significant number of tumour cells can make the patient unwell for a few days. The problems frequently seen include fever owing to release of inflammatory cytokines, lethargy and anorexia and in extreme cases, Tumour Lysis Syndrome. 

•   A poor response to treatment, because of inherent drug resistance, leads to progressive clinical signs.

Side effects

All drugs have the potential to cause side effects and these can range from mild to severe. On the whole most dogs tolerate chemotherapy well, but the most common side effects of concern to the client are vomiting and diarrhoea.

Commonly encountered side effects include: 

Fever

It is important to establish the cause of a fever rather than just dispensing antibiotics. A fever can be either infectious or inflammatory in origin. For the patient presenting with a fever the first thing to do is to check the white blood count (WBC) to see if the patient is neutropenic. If the neutrophil count is normal, infection is unlikely to be the cause of the fever. If the patient is neutropenic, look for the cause of the infection.

A urine culture (especially in females) is advisable and thoracic radiographs to rule out pneumonia. If the patient is pyrexic, then hospitalization for supportive care in the form of antibiotics, fluid therapy and anti-pyretics is required.

For patients with no evidence of infection and a normal neutrophil count, the cause of the fever would be inflammatory owing to release of cytokines – interleukin-1 (IL-1), and tumour necrosis factor (TNF), for example. Treatment includes supportive care, fluid therapy and anti-pyretics (NSAIDs /steroids). A dog that is febrile and neutropenic should not be treated as an outpatient.

Vomiting/diarrhoea

The most important consideration, when managing the side ef fects of chemotherapy, is to ensure that appropriate action is taken immediately, because most patients respond to medical management and good supportive care. This may mean hospitalisation for 24 to 48 hours to ensure adequate hydration in a dog with vomiting and diarrhoea.

In many cases, dispensing anti-emetics at the time of chemotherapy may be beneficial, especially for drugs that are particularly associated with nausea and vomiting – doxorubicin and cisplatin, for instance. In patients with mild signs of vomiting, outpatient treatment in the form of anti-emetics can be considered; but if the patient is depressed or dehydrated, then hospitalisation may be required. Currently the anti-emetic most frequently used is maropitant citrate (Cerenia, Pfizer).

Commitment to the individual is an important aspect of achieving a good outcome. One vital point to remember is that if the patient is unwell as a consequence of treatment, do not continue chemotherapy. Wait until the dog has had 24 hours eating without vomiting or having diarrhoea. If chemotherapy is given to a sick dog, the result will only be a dog that is very sick. If in doubt always wait and re-evaluate in a few days. It is also important to remember that if a patient has bad side effects from one drug, it should be stopped or the dose reduced. Never continue in the face of a bad reaction.

Safe handling of cytotoxics

Always treat cytotoxic drugs with respect. Do not handle them without wearing gloves. Special chemotherapy gloves are available; but if you choose not to use these, then double-glove using powder- free gloves. When giving chemotherapy, the eyes should be protected from splashing and a gow'n worn with a wrist band, such that the gloves and gown do not reveal any exposed skin.

Never divide chemotherapy tablets, such as cyclophosphamide, or open capsules such as CCNU; if reformulating is required this must be carried out by a pharmacist. For patients receiving intravenous chemotherapy, an intravenous catheter must be placed – do not give off the needle. Patients on a slow intravenous drip of chemotherapy should be closely monitored to prevent any dislodging of the line and the drug clearly labelled so that anyone coming to the room knows that this patient is receiving chemotherapy.

Chemotherapeutics should be handled in a fume hood; but if there is no fume hood, sealed delivery systems are available through Phaseal. All disposables used in the administration of chemotherapy should be discarded appropriately as per your clinical waste guidance for the disposal of cytotoxics.

The mode of excretion of cytotoxic drugs depends on the drug. Many are metabolised to inactive residues by the liver and excreted in the faeces, some are excreted primarily through the urine.

All excreta should be disposed of with other biohazardous waste. Gloves should be worn at all times when disposing of excreta or cleaning the kennel after a dog has received chemotherapy. Clients should be instructed to do the same at home and pregnant women should be instructed not to handle either oral chemotherapeutics or excreta.

Should a spill occur, the chemotherapy ‘spill’ kit should be used. These kits are commercially available but you can make your own. Any person cleaning up a spill should wear full protective clothing and dispose of all waste appropriately.

Understanding the human/animal bond

A very important part of nursing the lymphoma patient is an understanding of the human/animal bond. It is this deep commitment of the client to the individual animal that made them want treatment in the first place. This should above everything else be respected and cherished.

Clients whose dogs have lymphoma and are undergoing treatment are under a great deal of stress; so taking time with them is essential and just a few minutes chat’ when they come to pick up or drop off can be very reassuring.

Always remember that each situation is unique and that every patient is an individual. Many of these patients will be seen for months and the importance of recognising the needs of the individual (both human and canine) is invaluable to their well-being. The veterinary nurse is in many instances the very person who can provide that ‘little bit extra’ (Figure 3). 3

Figure 3: A contented patient

Author

Susan M North

BSc(Hons) PhD DVM DipACVIM DipACVR DipECVIM MRCVS

Susan obtained her PhD in 1982 from the Royal Marsden Hospital. She then went on to become assistant professor in the Department of Tumour Biology at MD Anderson Cancer Hospital in Houston, Texas, before deciding to move into veterinary medicine.

She received her DVM from Texas A&M and completed a residency in oncology at the AMC in New York. She is boarded in Medical and Radiation Oncology. In 2002, she established VRCC, a veterinary referral centre in Essex in which she installed the first linear accelerator in a private centre in Europe.

To cite this article use either

DOI: 10.1111/j.2045-0648.2011.00061.x or Veterinary Nursing Journal Vol 26 pp 234
-236

 

• VOL 26 • July 2011 • Veterinary Nursing Journal