“Cancer” is such an ominous and preoccupying presence in the subject of human health that we can all too easily forget that it affects other animals too, not least dogs. And just as with humans canine cancer comes in all manner of forms, due to all manner of causes, and with all manner of prognoses.
In the simplest sense cancer comes about when the natural process of cell division goes awry. Somewhere a cell with damaged or abnormal DNA divides and continues to divide, creating an uncontrolled and growing presence far beyond the needs of the normal cell replacement that keeps the body intact. The purposeless lump that results is a tumour
Just as with humans there are myriad causes for this abnormal cell division. It may be down to environmental or chemical factors. Dogs, fortunately, don’t tend to smoke cigarettes or drink alcohol, but they are exposed to sunlight, and may well come in contact with carcinogenic chemicals in the course of their life. Canine cancer may also be down to an inherited genetic tendency. But it may also simply be down to DNA damage caused through accumulated wear and tear. This is why cancers are most common in older dogs, and older people.
The most obvious symptom of cancer in a dog is some sort of lump. But you might notice other symptoms, including weight loss and a lack of appetite, a general lethargy and a sense of decline. At this point it’s time for the veterinary professionals to step in and make a diagnosis. If there’s no visible lump a scan or x-ray might be needed, and then, once a lump is found there’s need for a biopsy. Depending on the size and location of the tumour this might be done with a needle, or the whole thing might be removed in a simple operation. In many cases the tumour turns out to be “benign”. This means that, although it will continue growing where it is, it has no tendency to spread elsewhere in the body. Providing the tumour can easily be removed and has done no permanent damage to surrounding tissues or organs, a dog will usually make a full recovery. Sometimes, however, the tumour may be “malignant”, with the potential for its abnormal cells to spread and grow new tumours elsewhere. Just as with humans these are the cases that can sadly prove fatal.
Treatment of canine cancers has developed massively in recent decades, and much of what doctors have learnt about treating the disease in humans has been transferred to veterinary sciences too. Chemotherapies, radiotherapies and other, more innovative treatments can sometimes be applied to dogs, though these are of course often traumatic processes in their own right, with challenging side effects.