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Well, that’s the million dollar question, isn’t it? And the answer very much depends on the type of Leukaemia.
Leukaemia is a type of cancer resulting from an abundance of cancerous blood cells in the bone marrow, and no one is really sure of the cause in our pets. In humans it is thought that a virus, exposure to certain chemicals, and treatment with chemotherapy drugs or radiation therapy may all have a part to play in causing the dreaded disease. Sadly there is no way of preventing leukaemia.
Although leukaemia can be classified in many different ways, the most common form seen in cats and dogs is lymphocytic leukaemia, which can in turn be broken down into the acute (sudden onset) and chronic (long term illness) forms, known as ALL and CLL respectively. The different forms have differing clinical presentations and each form carries a different prognosis for your pet.
Diagnosis
In order to diagnose leukaemia your veterinarian is going to need to do the following:
Take a complete history and make a physical examination.
Do a complete blood count to evaluate the red and white blood cells as well as the platelets. This is an essential part of the diagnosis process. The red blood cells and platelets are often decreased in pets with leukaemia. In cases of ALL, the white blood cell count may be high or low, with the presence of abnormally large lymphocytes, called blasts. In CLL, the lymphocyte count is abnormally high, but the cells appear normal in shape and size. Results of the complete blood count can be strongly suggestive of leukaemia.
Many pets with leukaemia have a low red blood cell count (anaemia). Normally, an animal’s bone marrow responds to anaemia by releasing reticulocytes, so a reticulocyte count, which measures immature red blood cells in circulation, helps to evaluate the bone marrow function and categorise the cause of the anaemia.
A biochemical profile is done to evaluate blood sugar, blood proteins and electrolytes, as well as providing information about the patient’s liver and kidney function. This helps to give the veterinarian an overall idea of systemic health. Pets with leukaemia often have cancer cells working their way into the abdominal organs, which may lead to changes in the biochemical profile. In addition, some pets have an elevation in their blood calcium level, which can be associated with several types of cancer. A rise in the globulin level, which is a blood protein, can also be seen in pets with leukaemia.
X-rays of the chest are a useful way for the veterinarian to look for evidence of spread of cancer to the lungs. Abdominal x-rays or an abdominal ultrasound exam also help to show further evidence of cancer. It is not uncommon to find an enlarged liver and/or spleen in patients with leukaemia.
The definitive test for making a diagnosis of leukaemia is by taking a sample of bone marrow to determine the presence of cancer cells within. This involves placing a specialised needle within a bone and suctioning cells out. This procedure is usually done under heavy sedation or anaesthesia, and is most commonly performed by a specialist.
Because leukaemia is a disease of blood cells, the cancer often spreads throughout the body. Lymph nodes and abdominal organs may become enlarged when they are infiltrated with cancer cells. In cases where the organs are abnormally large, fine needle aspirates of these tissues will often confirm the suspicion of cancer in a given organ.
Prognosis
The chronic form of lymphocytic leukaemia is known as chronic lymphocytic leukaemia, or CLL, and is usually seen in older pets (over 10 years). Pets with CLL will often be ‘under the weather’ with vague signs of illness, including weight loss and lethargy that can be present for months or even years before a diagnosis is made. The prognosis for animals with CLL is fairly optimistic in that, with appropriate treatment, they will often live for several years after diagnosis.
Pets with the acute form – acute lymphoblastic leukaemia, or ALL – are generally very ill, often have a fever, will show clinical signs suddenly, and sadly the prognosis is very poor, as a pet with ALL will often die within days or months of diagnosis. This form is more common in certain large breed dogs of any age. Although the cancer cells may respond to therapy, the presence of secondary complications often creates severe illness. In addition to being at risk from infection, these patients are often profoundly anaemic, may develop life-threatening bleeding disorders, and can even suffer from neurologic disease such as seizures and strokes.
Treatment
Treatment for the different types of leukaemia will vary quite considerably.
A cocktail of different chemotherapy drugs are used in combination for the treatment of both ALL and CLL. Initially, this will involve weekly visits to the veterinarian. The response to chemotherapy in patients with ALL is often disappointing; however, most CLL patients do well with chemotherapy.
Because many of the animals with ALL are anaemic, blood transfusions are often required to stabilise the pet. This requires careful monitoring and, of course, access to canine and feline blood products. Similar to human blood transfusions, the donor blood type must be compatible with the recipient's blood type. Transfusions are usually only available at specialty hospitals or emergency centres.
Pets with ALL often have a low proportion of normal white blood cells. White blood cells work to fight infection. Because of this, they run a very real risk from opportunistic bacterial infections that can be life threatening. Chemotherapy can also worsen the situation, as many drugs can lower the white blood cell count even further. Treatment with antibiotics is therefore needed to help prevent infection in these animals. If an infection is already present, cultures of urine, blood, and possibly other fluids are necessary to choose the appropriate antibiotic therapy.
In addition to the above, severely sick pets will require intravenous fluid therapy to combat dehydration, keep blood electrolyte levels balanced, and maintain normal blood pressure and kidney function. Nutrition is a vital part of therapy. Cancer patients lose weight rapidly and may not be able to get enough nutrients, especially if they are not eating, or are experiencing gastrointestinal illness. Feeding tubes or intravenous feeding may be necessary to sustain them.
Optimal treatment for your pet requires a combination of home and professional veterinary care.
Home Care
At home a pet must be given all his medications as directed by the veterinarian, as many patients with leukaemia are predisposed to secondary infections due to a compromised immune system. Exposure to animals outside of the household should be minimised as much as possible.
Monitor your pet at home for signs of lethargy, continued weight loss, anorexia, and general weakness. Learn how to check your pet's temperature with a rectal thermometer and call the veterinarian if a fever is present.
Follow-ups with your veterinarian will include weekly evaluations of the complete blood count to monitor red and white blood cell counts and platelet levels. This is one important way to measure response to treatment. It should also include a physical examination where your veterinarian will monitor weight, body condition, and temperature and palpate lymph nodes and internal organs to assess their size. Repeat x-rays or ultrasound exams may be indicated as well to track changes in organ size.
Once your pet is stable, less frequent exams will be needed but close contact with your veterinarian is required for the rest of your pet’s life.
What to look for!
These may not necessarily mean your pet has leukaemia, but if he exhibits any of these signs it’s best to get him checked out:
Loss of appetite
Weight loss
Pale gums
Lack lustre and lethargic
Bleeding or bruising
Vomiting
Diarrhoea
Lameness
Increased drinking and urinating
Seizures
Abnormal behaviour
Generally sick
It might be this
Leukaemia can mimic many other diseases, making laboratory findings crucial in making a diagnosis. Other conditions that may cause similar clinical signs are:
Neoplasia (cancer), especially lymphoma. Lymphoma is another form of cancer that is quite similar to leukaemia and involves cancerous lymphocytes.
Autoimmune disease. Autoimmune or immune-mediated diseases occur when the body destroys its own cells. Clinical signs of pale gums and bleeding or bruising can often be seen in autoimmune disease and leukaemia.
Severe bacterial infection/sepsis.
Severe inflammatory conditions such as pancreatitis or pneumonia.
Feline Leukaemia Virus (FeLV)
The Feline Leukaemia Virus (FeLV) is different to Feline Leukaemia in that it is a type of virus called a retrovirus. Retroviruses are species-specific which means that FeLV is specific to cats only and cannot be caught by humans or their other non-feline pets. FeLV suppresses your cat's immune system, causing her to become susceptible to many diseases which she might otherwise be able to fight off.
A cat that tests positive for FeLV will not necessarily contract Feline Leukaemia. However, cats that do test positive for the virus are more likely to catch any one of a number of diseases including, but not limited to, leukaemia, lymphoma, lymphosarcoma or opportunistic infections. Not all cases of leukaemia and lymphosarcoma are caused by FeLV.
FeLV-infected cats can sometimes live for years. Stress and exposure to ill animals should be avoided, and FeLV-positive cats should be kept indoors both to protect them from exposure to disease and also to prevent them from spreading FeLV to other cats.
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