Cancer is one of the health conditions that dogs owners should know about, because it affects quality of life, and it is easier to manage when it is caught early. This guide explains what cancer is, the signs to watch for, what causes it, how it is diagnosed, how it is treated, whether it can be prevented, and how to live with a dog that has it. Every suggestion here is general guidance, not a prescription for an individual dog.
Golden Retrievers are the focus of this guide. A typical adult Golden Retriever weighs 25–34 kg, with a typical lifespan of 10–12 years, and is commonly described as friendly, outgoing, active. Golden Retrievers are known to have a higher risk of some cancers than most breeds, and cancer is one of the most common causes of death in the breed. That does not mean every Golden Retriever will develop cancer, but it does mean owners should check their dog regularly and mention any new lump to the vet promptly. The rest of this guide covers the condition itself — what it is, the signs, the causes, how it is diagnosed, how it is treated, and how to live with it — with the breed in mind throughout.
What is cancer in dogs?
Cancer is a condition where abnormal cells grow and divide without control, forming a lump or spreading through the body. There are many kinds of cancer, in many parts of the body, and they behave very differently: some grow slowly and stay in one place, others grow fast and spread quickly, and some are cured by removing them while others need more treatment. Cancer is more common in older dogs, and some breeds are more prone than others, but any dog can develop it, and a lump in a dog should always be checked by a vet — most lumps are not cancer, but the only way to know is to check.
The rest of this guide covers the signs, the causes, how cancer is diagnosed, how it is treated, whether it can be prevented, and how to live with a dog that has it. A dog with cancer should be checked by a vet, because the right treatment depends on the individual dog, its age, and how advanced the condition is — and because some of the signs of cancer can also be signs of other conditions, which need a vet to tell apart. The dog ideal weight calculator works out a target weight range, and the when is a dog considered a senior guide gives the senior thresholds by size.
Signs of cancer in dogs
The signs of cancer in dogs are listed below. Not every dog with cancer will show every sign, and some dogs will show only one or two — but any one of these signs, especially if it lasts more than a few days or gets worse, is worth mentioning to a vet. A dog that is bright, eating, drinking, and otherwise well between episodes is less likely to be seriously ill than a dog that is lethargic, off its food, or losing weight — but the only way to know is to check.
- A lump or swelling that grows, changes, or does not go away.
- Weight loss, even though the dog is eating normally.
- A sore that does not heal, or a wound that keeps coming back.
- Lethargy, weakness, and a dog that seems generally unwell.
- A loss of appetite, or a dog that goes off its food.
- Difficulty eating, breathing, or going to the toilet, depending on where the cancer is.
- Bleeding, discharge, or a bad smell from a lump or a sore.
If two or more of those signs apply, or if one sign is severe — a dog that cannot urinate, cannot breathe, cannot stand, or has had a seizure lasting more than five minutes — see a vet the same day. Those are signs that need a vet, not waiting. Bring a note of when the signs started, how often they happen, and what the dog eats and drinks — that information helps the vet far more than a guess about the cause. The how to tell if your dog is overweight guide gives the hands-on check for weight, which matters for many of these conditions.
Causes and risk factors for cancer
Cancer is caused by changes in the cells' DNA, and those changes can be caused by age, genes, and the environment. Age is the biggest risk factor: the older a dog is, the more likely it is to develop cancer, because the cells have had more time to change. Some breeds are more prone than others — Golden Retrievers, for example, are known to have a higher risk of some cancers — and some cancers are linked to the environment, such as skin cancer from sun exposure in dogs with thin coats or pale skin. In most cases the exact cause is never found.
Some dogs are more prone to cancer than others, because of their genes, their breed, their size, or their age — but breed and age are not destiny, and a dog of any breed can develop cancer. What an owner can control is weight, food, exercise, and vet checks: a dog at a healthy weight, with measured food and daily exercise, is less likely to develop cancer and will cope better with it if it does. A dog that is overweight, that eats a poor diet, or that never sees a vet is more likely to develop cancer and to have it found late, when it is harder to treat.
How cancer is diagnosed
A vet diagnoses cancer by examining the lump or the dog, and then by taking a sample — a fine needle sample, where a thin needle is used to take a few cells, or a biopsy, where a small piece is removed — and sending it to a laboratory. The vet may also run blood tests, take X-rays, or use an ultrasound to see whether the cancer has spread. A lump that is growing, changing, or not going away should be checked promptly, because cancer is easier to treat when it is found early, and some cancers are cured by removing them while they are still small.
If you are worried about your dog, see a vet and mention cancer by name, with the signs you have seen and when they started. Bring a note of what the dog eats, how much, and any medicines it takes, and whether it has had cancer or a related condition before. A video of the signs, if it is safe to take one, helps the vet far more than a description — especially for seizures, limping, or breathing problems. Do not try to diagnose cancer yourself, and do not buy medicines or special diets for it without veterinary advice, because the wrong treatment can make it worse.
Treatment and management of cancer
Treatment depends on the kind of cancer, where it is, and how far it has spread. The most common treatment is surgery to remove the lump, and in many cases that is all that is needed. Some cancers also need chemotherapy, radiotherapy, or other medicines, which the vet will discuss with the owner. Treatment is a big decision, and it is made with the vet, weighing the dog's age, health, and quality of life against the treatment and its side effects. Some owners choose not to treat, and to keep the dog comfortable instead — and that is a valid choice, made with the vet, not on the basis of a web page.
Treatment is a decision made with the vet, weighing the dog's age, health, and quality of life against the treatment and its side effects. Some owners choose not to treat, and to keep the dog comfortable instead — and that is a valid choice, made with the vet, not on the basis of a web page. Whatever is decided, the treatment must be followed every day, at the same times, and the dog must be checked regularly, because cancer changes over time, and the treatment needs to change with it. Do not stop a medicine suddenly, and do not change the dose without veterinary advice.
Living with a dog with cancer
A dog with cancer can live a full and happy life with the right care, but it needs a routine: treatment as the vet advises, regular checks, and a close watch on appetite, weight, and energy. The owner must watch for the signs coming back — a new lump, weight loss, lethargy — and mention them to the vet promptly. Quality of life matters most: a dog that is bright, eating, and comfortable is doing well, whatever the diagnosis, and a dog that is in pain, not eating, or not itself needs a vet visit to talk about what is best. The vet will help the owner decide what is best for the dog at each stage, including when the kindest choice is to let it go.
Keep a routine: the same times for food, medicines, walks, and play, the same places for furniture, food, and water, and a calm, predictable home. Keep a note of appetite, drinking, weight, and behaviour, and mention any change to the vet promptly — a change that lasts more than a few days, or that gets worse, is worth a vet visit. Keep the dog at a healthy weight, with measured food and daily exercise at a level that suits its body, and keep vet checks regular: once a year as an adult, and twice a year as a senior. The senior dog diet guide covers feeding older dogs, and the dog calorie calculator works out daily calories for any weight.
Why Golden Retrievers are prone to cancer
Golden Retrievers are known to have a higher risk of some cancers than most breeds, and cancer is one of the most common causes of death in the breed. That does not mean every Golden Retriever will develop cancer, but it does mean owners should check their dog regularly and mention any new lump to the vet promptly. That does not mean every Golden Retriever will develop cancer — it means owners of the breed should know the signs, and mention them to the vet early, because cancer is easier to manage when it is caught early. A Golden Retriever that is kept at a healthy weight, with measured food and daily exercise, is less likely to develop cancer and will cope better with it if it does.
Can cancer be prevented?
Cancer cannot always be prevented, because much of it is about age and genes — but the risk can be reduced. Keep the dog at a healthy weight, because obesity is linked to some cancers, and keep it out of strong sun, because sun exposure causes skin cancer in dogs with thin coats or pale skin. Have the dog checked regularly, and check it yourself at home: run your hands over its body once a month, and mention any new lump to the vet promptly. A lump found early is far easier to treat than one found late.
Early checks matter most: have the dog checked regularly, so cancer is found early, when treatment works best. Keep the dog at a healthy weight, with measured food and daily exercise, and mention any change in drinking, eating, weight, or behaviour to your vet early, because a change caught early is easier to treat than one left for weeks.
For related reading, see the Golden Retriever food guide, the Golden Retriever lifespan guide, the dog ideal weight calculator, the dog body condition score chart, the how to tell if your dog is overweight guide, the senior dog diet guide, the dog calorie calculator, the when is a dog considered a senior guide.
Frequently asked questions
What is cancer in dogs?
Cancer is a condition where abnormal cells grow and divide without control, forming a lump or spreading through the body. There are many kinds of cancer, in many parts of the body, and they behave very differently: some grow slowly and stay in one place, others grow fast and spread quickly, and some are cured by removing them while others need more treatment. Cancer is more common in older dogs, and some breeds are more prone than others, but any dog can develop it, and a lump in a dog should always be checked by a vet — most lumps are not cancer, but the only way to know is to check.
What are the signs of cancer in dogs?
The most common signs are: A lump or swelling that grows, changes, or does not go away. Weight loss, even though the dog is eating normally. A sore that does not heal, or a wound that keeps coming back. See the full list above for every sign to watch for, and see a vet promptly if two or more apply, or if one sign is severe.
What causes cancer in dogs?
Cancer is caused by changes in the cells' DNA, and those changes can be caused by age, genes, and the environment. Age is the biggest risk factor: the older a dog is, the more likely it is to develop cancer, because the cells have had more time to change. Some breeds are more prone than others — Golden Retrievers, for example, are known to have a higher risk of some cancers — and some cancers are linked to the environment, such as skin cancer from sun exposure in dogs with thin coats or pale skin. In most cases the exact cause is never found.
How is cancer diagnosed?
A vet diagnoses cancer by examining the lump or the dog, and then by taking a sample — a fine needle sample, where a thin needle is used to take a few cells, or a biopsy, where a small piece is removed — and sending it to a laboratory. The vet may also run blood tests, take X-rays, or use an ultrasound to see whether the cancer has spread. A lump that is growing, changing, or not going away should be checked promptly, because cancer is easier to treat when it is found early, and some cancers are cured by removing them while they are still small.
How is cancer treated?
Treatment depends on the kind of cancer, where it is, and how far it has spread. The most common treatment is surgery to remove the lump, and in many cases that is all that is needed. Some cancers also need chemotherapy, radiotherapy, or other medicines, which the vet will discuss with the owner. Treatment is a big decision, and it is made with the vet, weighing the dog's age, health, and quality of life against the treatment and its side effects. Some owners choose not to treat, and to keep the dog comfortable instead — and that is a valid choice, made with the vet, not on the basis of a web page.
When should a dog with cancer see a vet?
See a vet promptly if the dog shows any of the signs above, especially if they last more than a few days or get worse — and the same day if the dog cannot urinate, cannot breathe, cannot stand, has had a seizure lasting more than five minutes, or is lethargic or off its food. Bring a note of when the signs started and what the dog eats and drinks. A dog with cancer should be checked by a vet, because the right treatment depends on the individual dog, its age, and how advanced the condition is.
Results on this page are estimates for general information only and are not veterinary advice. If your pet is ill, underweight, overweight, pregnant, or has a health condition, consult your veterinarian before changing diet or care.