Cancer in Dogs
Dogs are affected by cancer just as we humans are, and the disease can affect any of their organ systems, as well as their soft tissue and bones. Advances in medicine mean that nowadays, it is often possible for an early diagnosis to be made and for better treatment to be given, as there are specialised hospital departments for radiotherapy and chemotherapy.
What symptoms could be a sign of cancer in dogs?
The symptoms of cancer can take many forms, and often do not initially appear to indicate a serious illness at all. Many illnesses involving tumours develop gradually to begin with, which means that it is barely noticeable that anything is amiss with the patient.
Signs can include, among others:
- Symptoms of feeling unwell: vomiting, loss of appetite, diarrhoea, constipation, sensitive stomach
- Changes in behaviour: increased tiredness, fatigue, groaning, restlessness at night, disordered sleep, aggression/passiveness
- Visible lumps (nodes) on various body parts, which may, among other things, affect mobility
- Neurological abnormalities: cramps, symptoms of paralysis
- Blood in the urine/stool
What to do if a tumour is diagnosed
Today’s cancer treatments
Depending on the type of tumour in question, the symptoms of cancer can vary considerably. Often, the beginning of the illness is characterised only by very general symptoms such as diarrhoea, vomiting, fever, weight loss, refusing food, and fatigue. A thorough diagnosis by the vet will shed light on what is going on. Once the type of tumour has been determined, an appropriate treatment plan will be worked out which includes surgery, chemo or radiotherapy, or a combination of these treatment methods. Accompanying pain therapy helps to assuage the dog’s suffering. The most common tumours in dogs affect the lacteal glands and lymph nodes, the skin, the muzzle area, the bones and the soft tissue.
A healthy lifestyle lowers the risk of cancer
Unfortunately, there is no guaranteed way to prevent cancer. A healthy lifestyle with plenty of exercise and high-quality food are, however, proven to lower the risk of cancer. Try to expose your dog to as little strong sunlight and as few exhaust fumes as possible, and choose a species-appropriate, natural feed free from synthetic flavourings and preservatives. If your dog already has cancer, do not delay getting treatment under any circumstances. Each day of waiting decreases your dog’s prospects of recovery, or of being able to extend their life. Ideally, take your dog to a cancer clinic for animals which uses the latest types of treatment.
Types of cancer in dogs
Tumours of the nose
- Rhinitis = inflammation of the nasal mucous membrane with discharge (initially on one side)
- One-sided, later also two-sided stenosisation (narrowing) of the nasal cavity
- Changes to the shape of anatomy in the nasal area or paranasal sinus area due to the tumour breaking through under the skin
- Growth of the tumour into the oral cavity, the eye socket or via the ethmoid bone into the brain
- Often, obstruction (shift) of the tear duct or hindering of the outflow of frontal sinus secretions (making infections etc. more likely)
Just as is the case in humans, there are a range of different tumours which can affect dogs’ skin tissue. These lumps can be both benign and malignant. Such tumours are often seen in middle-aged and older dogs. They range from the simple papilloma (wart) to squamous cell carcinomas and mast cell tumours. It is usually not possible to tell from outward appearance alone what type of tumour is present.
- Often no noticeable symptoms initially
- Changes in the skin: lumps and bumps
- In the case of larger lumps, there may also be restrictions to mobility, pressure sores or chafing of the lump, accompanied by inflammation
- In case of malignant tumours that spread, additional organ symptoms are also possible over time
Mast cell tumour
- Appearance can vary greatly
- Tends to be found on the body and the limbs
- Signs of malignancy: rapid growth, superficial disintegration of the nodules, appearance of satellite nodes, increase in size of primary lymph nodes
- The appearance of the tumour can change rapidly due to the formation of oedemas (build-up of fluid in the tissue) and inflammation
- Metastatic spread to the liver and spleen is possible later
- Metastases in the lungs are relatively uncommon
What is particular about these tumours:
Signs can include:
- Painless enlargement of the lymph nodes, particularly in the shoulder (neck) and the hollow of the knee, enlargement of the spleen and liver as well as infiltration of the lungs and/or bone marrow
- May be asymptomatic initially
- Then general symptoms later: listlessness, lack of appetite, fever, emaciation
- Diarrhoea, loss of appetite, vomiting, bowel obstruction, emaciation
- Coughing, shortness of breath, formation of oedemas, pleural effusion
- rare, can be a lymphatic infiltration of the central nervous system, of the spinal cord, the skin, the nose, the larynx etc.
- Distinction between epitheliotropic (focal or generalised reddened to flaky dermatitis with ulcers or papule formation = widespread changes to the skin) and non-epitheliotropic (affecting the middle and lower layers of the skin)
Blood tests, image procedures (x-ray, ultrasound), aspiration cytology of altered lymph nodes, of the spleen, liver and bone marrow, and biopsies
Treatment by an oncologist (surgery, palliative radiation, chemotherapy). The aim is for treatment to begin as early as possible in order to enable the dog to enjoy good quality of life in remission, and for the remission to be maintained by way of maintenance treatment.
Very bad without treatment. With treatment, the prognosis depends on the location and stage of the cancer. With treatment and favourable circumstances, a life expectancy of one year or more can be achieved.
- Benign tumours often remain symptomless
- Malignant tumours: vomiting, loss of appetite, emaciation, listlessness and usually blood in the stool (not visible to the naked eye) and pain when the stomach area is touched
- In older dogs, vomiting blood is always a reason to consider the possibility that the dog may be suffering from a gastric tumour.
For the diagnosis, an image procedure is carried out (x-ray, ultrasound) and a tissue sample is taken. Treatment is difficult and it is recommended that a specialist be consulted. If it is possible for an operation to be carried out, surgery may be conducted, as well as chemo/radiotherapy.
Benign tumours such as leiomyomas or adenomatous polyps can usually be removed effectively by way of surgery (curatively). The prognosis for malignant tumours is bad.