How to Prevent Dog Cancer
To prevent your dog from getting cancer, feed it a healthy diet with controlled portions since being overweight can contribute to cancer. Since potential carcinogens are just as bad for animals as they are for humans, try and keep your dog away from tobacco smoke, vehicle exhaust, detergents, weedkillers, and other carcinogens. Along with these preventive steps, check your dog regularly for any new lumps or bumps once a week so you can take it to the vet if you notice one is rapidly growing in size. You may also want to consult your vet about the impact of vaccinations on your dog when it comes to preventing cancer.
Limit exposure to carcinogens. Exposure to potential carcinogens, such as tobacco smoke, is just as damaging to animal health as it is to human health. Minimize exposure to chemical such as flame retardants, weedkillers, tobacco smoke, vehicle exhaust, detergents, and air fresheners. Consider the impact of vaccinations. Holistic veterinarians argue that over-vaccination is a stimulus for cancer in dogs. While there does seem to be a slight risk of sarcoma (a cancer of the soft tissues at the site of injection) with the rabies vaccine, this needs to be balanced against the horrific consequences of acquiring rabies infection. As for other vaccinations, there is no hard and fast evidence that this is the case, and more work needs to be done to prove the point one way or the other. In the case of the rabies vaccine, the cause of the increased risk is not known, and one theory is that stabilizers added to the vaccine (rather than the rabies virus itself) are responsible. Of these, aluminium has been most mentioned, although this argument is not completely convincing, as some vaccines that don't contain aluminum have also caused sarcoma. Discuss the risks with your veterinarian (as reactions are very rare, especially in dogs) before deciding not to have the vaccination. Deciding against vaccination to err on the side of caution about causing cancer, does place your pet at the considerably greater risk of picking up diseases that can be fatal or debilitating. Be aware if you opt against vaccination, you could be reducing a tiny risk but increasing a larger risk, so your decision should be carefully balanced on a risk evaluation basis. Also be aware that if you opt against giving the rabies vaccination you may be breaking the law in your state. Feed your dog a healthy diet. It is a good idea to keep your dog in lean or normal body condition by controlling how much he eats, rather than letting him become overweight. There is also a vocal lobby who believe that additives in prepared dog food are a cancer risk. There are no clinically proven studies to prove this point, so this is something you need to consider for yourself. It is best to reach your own conclusion by researching the literature and checking for trustworthy scientific papers where the weight of evidence is compelling. At the present time, this evidence is lacking, which means one opinion is as good as another. The alternative to a commercial diet is a home-cooked diet made from organic foods. However, this is not as simple as it seems because dogs have complex nutritional needs. It is all too easy to feed a dog a diet deficient in vital minerals or proteins. In the long term this can cause deficiency disease, which is every bit as debilitating as some forms of cancer. Weigh the pros and cons of desexing. While neutering can decrease the risk of certain cancers, it increases the chances of others. Because the risk of certain cancers depends heavily on a variety of factors, such as age and breed, these pros and cons should be thoughtfully discussed with your veterinarian in order to decide the best course of action for your particular dog. Some of the debates about desexing revolve around at what age to spay and neuter animals. At present, one of the strong arguments for spaying a female dog is that it protects her against mammary cancer in later life. The chances of mammary cancer in a spayed female after she has had two menstrual cycles is one in four. For a female spayed between her first and second season, this risk falls to one in 10,000, while for a bitch spayed before her first season the risk is just one in 25,000. This is a compelling reason to get females spayed at a very young age. However, early spay seems to place female dogs at slightly greater risk of certain other cancers, such as hemangiosarcoma (cancer of the blood vessels) and osteosarcoma (bone cancer), especially in larger breeds. This increased risk is lower than that of mammary cancer, but these other cancers are all potentially aggressive and difficult to treat, whereas there is a spectrum of seriousness for mammary cancer. With regard to male dogs, neutering removes the testicles and therefore the risk of testicular cancer. However, studies indicate a slightly increased risk of prostatic cancer and bone cancer (again, especially in large breed dogs). Pay attention to bodily and behavioral changes. Be vigilant for general changes in your pet's eating habits, bowel movements, and demeanour. If these become abnormal the cancer is just one possible explanation amongst many, but again, the sooner it is checked out the better the likely outcome for the pet. Check your dog regularly. It is essential to check your dog over regularly in order to detect new lumps and bumps. Once a week check your pet over from head to tail, feeling her skin, and becoming familiar with how her body feels. If you find a skin mass or a lump under the skin, the very least you should do is monitor it. Measure the lump with a ruler once a week and write the measurement down. If the lump is increasing in size rapidly, then a vet check is essential. Get lumps and bumps checked by a veterinarian. Getting a lump checked by a professional early gives your dog the best chance of a full recovery if the lump is cancerous. In a worst case scenario, where the lump is malignant and liable to spread, surgical removal at the earliest opportunity reduces that the cancer will spread to other parts of the body. Plus, intervention when a lump is small means surgery is less complex and the outcome is more likely to be successful. 
Limit exposure to carcinogens. Consider the impact of vaccinations. Feed your dog a healthy diet. Weigh the pros and cons of desexing. Pay attention to bodily and behavioral changes. Check your dog regularly. Get lumps and bumps checked by a veterinarian. 