They can't tell you when something is wrong, but there are warning signs of cancer every pet owner can look for. If your dog shows any of the following symptoms, see your vet. Early diagnosis could save your pet's life.
1. Lumps and skin changes
Not all lumps and bumps on or under your dog's skin will be cancerous, but if you notice a hard lump that feels well-attached to underlying tissue, or one that seems to be growing, get it checked out. A swollen lump by the jaw near the neck, in the arm pits, in the groin area or on the rear legs behind the knees, could be a swollen lymph node. Cancer of the lymph nodes is the most common cancer found in young dogs.Watch out for changes to your dog's skintoo. Small skin lesions and wounds or sores that do not heal can also be potentially cancerous.
See also: Is your dog depressed?
2. Lethargy / collapsing
Most dogs slow down gradually with age but tumours can cause changes in a short space of time. If your dog appears weak, sluggish, depressed or lethargic (less responsive or not greeting people at the door as usual) in the space of a week or two, get them checked over. See your vet immediately if your dog collapses, even if they seem fine the next day.
Coughing can be a sign of lung cancer. While there's no need to worry if your dog coughs now and then (especially small breed dogs who are prone to windpipe problems), you should see your vet if the cough worsens and/or continues for more than a few days.
4. Weight loss
Weight loss can be a sign of cancer, particularly if your pet has a gastrointestinal tumour. While many dogs with this type of cancer will stop eating, others will continue to eat the same amount but still shed the pounds. If your dog starts losing weight and you haven't made any changes to their diet or exercise, make an appointment with your vet. Any major changes in appetite/thirst should also be reported.
5. Weight gain / bloating
It's not just weight loss – weight gain and bloating can also signal a problem. If your dog is eating less or the same amount but is packing on the pounds, get it checked out. A growing or ruptured tumour can cause an animal's abdomen to appear enlarged.
6. Four breath / mouth changes
Don't forget to check your dog's mouth too. Sores, lumps, a bad smell (worse than usual doggy breath), bleeding, and changes to the colour of gums can all signal oral cancer. Difficulty eating (prolonged chewing, reluctance to chew or food dropping from the mouth) as well as bleeding after eating, drinking or chewing toys can also signal a problem. Nosebleeds are another sign of cancer, particularly in older animals.
7. Changes in toilet habits
Occasional diarrhoea is unlikely to be a problem, but if it continues or gets worse, it's worth speaking to your vet. A dog that constantly whines to do their business and has trouble urinating or with bowel movements should be checked out. Vomiting and blood in the urine or stools is a common symptom of cancer.
Keep a look out for any unusual discharge. Continual discharge from the nose can be caused by facial tumours, while eye discharge can signal an eye tumour.
Sudden and uncontrolled behaviour, such as champing and chewing, jerking of the legs, or foaming at the mouth, should never be ignored, particularly in older dogs. Seizures can be a sign of brain tumours.
10. General pain or discomfort
Pain is one of the most common side effects of cancer in dogs – just as it is for humans. If your pet whines or cries when you pat them, pick them up, or when they eat, see your vet. Limping while walking is mostly associated with arthritic issues and joint or muscle diseases, but it can also be a sign of bone cancer.
Three related books that may be of interest:
The Natural Vet's Guide to Preventing and Treating Cancer in Dogs, £11.69
The Dog Cancer Survival Guide, £21.65
Cancer in Dogs, £7.80