Inflammation and Cancer

Causes of Chronic Inflammation

When the body has an injury or infection, it launches an acute inflammatory response to heal the injury or fight the infection. When the inflammatory process fails to stop after the injury or infection is resolved, the result is chronic inflammation. Inflammation and cancer are inextricably linked.²

There are many causes of chronic inflammation and many diseases other than cancer that can result from chronic inflammation. Some of these include:

• Diabetes¹
• Cardiovascular disease¹
• Allergies¹
• Chronic obstructive pulmonary disease (COPD)¹
• Atopic dermatitis⁹
• Arthritis and other joint diseases¹
• Chronic enteropathy¹⁷

Chronic Inflammation and Cancer

Chronic inflammation is a risk factor for cancer.¹ Before going on, let’s establish a couple of things:

• This does not mean that inflammation or even chronic inflammation always causes cancer. It simply means that chronic inflammation increases the risk of developing cancer.
• It also does not mean that removing all sources of inflammation (which is not even possible) will guarantee that your dog will live cancer-free.

Cytokines and Their Role in Inflammation

Cells and their surrounding tissues undergo a lot of changes in response to inflammation. When inflammation becomes chronic, one of the many changes that occurs includes a chronic increase in inflammatory cytokine levels.

Cytokines are molecules that are released from both immune and non-immune cells and help regulate the body’s inflammatory response. Elevated cytokine levels can promote cells becoming cancerous and promote the growth of existing tumors or pre-cancerous cells.²

Chronic Inflammation Causes and Risk Factors

Like humans, there are many sources of chronic inflammation in dogs. Some risk factors for developing chronic inflammation include:

• Age¹
• Obesity²
• Genetics²
• Lifestyle factors¹
• Environmental factors¹

We have no control over some of these factors, such as genetics and age, but we can influence, to some degree, some of the lifestyle and environmental factors that cause chronic inflammation.

There are no specific breed predispositions for chronic inflammation, but there are some breeds that are predisposed to certain conditions that are associated with chronic inflammation:

• German Shepherds and Rough Coated Collies have a predisposition to chronic pancreatitis,⁸ or inflammation of the pancreas.
• Golden and Labrador Retrievers, German Shepherds, English Bulldogs, Boxers, Pugs, Irish Setters, Dalmatians, Lhasa Apsos, Shih Tzus, Miniature Schnauzers, and terriers (West Highland White, Pit Bull, Scottish, Wirehair Fox, Welsh, Boston, and Cairn) all have a predisposition to atopic dermatitis,^9-11 a chronic inflammatory condition of the skin.
• Boxers, Cairn and Scottish Terriers, Labrador Retrievers, Shetland Sheepdogs, Basset Hounds, Cocker and Cavalier King Charles Spaniels, Longhaired Dachshunds, Beagles, and some giant breeds are more prone to obesity,^2,12 which is associated with chronic inflammation.
• Osteoarthritis is common in dogs, and especially common in large breed dogs including Mastiffs, Boxers, Italian Cani Corsi, German Shepherds, Golden and Labrador Retrievers, and Bernese Mountain Dogs.¹²
• Weimaraners, Rottweilers, German Shepherds, Border Collies, and Boxers have a predisposition for developing chronic enteropathy, which is uncontrolled inflammation in the gastrointestinal (GI) tract.¹⁷

Environmental and lifestyle factors that have been shown to contribute to chronic inflammation include obesity,² diet,¹ stress,¹ air pollution,^3-5 herbicides,⁶ and pesticides.⁷

Our ability to control these different factors varies, and no single factor can be blamed for developing chronic inflammation or cancer. Please don’t beat yourself up if you have had these things in your environment. Everyone has, and they are not all in our control.

How to Reduce Risk of Chronic Inflammation

Given the many potential triggers of chronic inflammation, we cannot possibly avoid all of them, but we can take steps to reduce some of the risk factors for developing chronic inflammation.

Obesity

Obesity is the most common nutritional disease in dogs,² with up to 50% of the dog population in the United States being overweight or obese.¹⁴ This disease is also common in humans, and it is often associated with feelings of embarrassment or low self-esteem.

Please keep in mind that obesity is NOT simply a cosmetic issue resulting from poor self-control. It is a chronic metabolic disease that can be difficult to manage but must be addressed to minimize the risk of developing health problems that are associated with being overweight or obese.

Excess fat cells cause the increased secretion of pro-inflammatory cytokines, eventually resulting in chronic low-grade inflammation throughout the body.² As with most things, prevention is the best medicine. It is usually much easier to prevent your dog from becoming overweight than it is to help her lose weight.

Monitor Calories

The most important step to preventing your dog from becoming overweight is to feed the correct amount of food needed by your dog for her current life stage. This can be tricky because your dog’s needs will change throughout life depending on age and growth stage, activity level, and any injuries or illnesses that may occur.

Collaborate with your veterinarian or a veterinary nutritionist on this to determine exactly how much food your dog needs for her current life stage. Do not rely on the feeding guidelines on the label of the food you use, as these are broad and often grossly overestimate how much food your dog needs.

Be very honest with yourself about the amounts you are feeding, including treats. What seems like a small treat can add up quickly, especially for smaller dogs.

Your vet can easily calculate your dog’s daily caloric needs with some precision and can then show you how to calculate exactly how much food that is using the nutritional content information on the label of the food you use.

Monitor Your Dog’s Body Condition

Ask your vet to teach you how to assess your dog’s body condition score so that you can pick up on subtle differences in weight changes without a scale. This is especially important for long-haired dogs where it may not be as obvious if they begin to gain weight.

Just like with people, weight gain can be slow and insidious, creeping up without much notice. Using these tools will help you keep your dog at a healthy weight, or if your dog is already overweight, will help you stay steadily on her weight loss plan.

Also keep in mind that weight loss is a slow process. Don’t get discouraged! If you have been following a plan for months with no results, it may be time to reassess the plan with your veterinarian or seek the advice of a veterinary nutritionist. Your dog may simply need a different food with a different nutrient profile.

Dietary Considerations for Inflammation

There is no single “best” diet for dogs. What works well for one dog may not work for another. If your dog has no health issues and you want to feed a commercial diet, choose a high-quality food and consider supplementing it with fresh, healthy whole foods.

Be sure to include any foods you supplement in calorie calculations to avoid inadvertently overfeeding. Also be sure to check that any foods you may supplement with are safe for your dog, as some healthy human foods (such as grapes or raisins) can be toxic for dogs.

If your dog suffers from an inflammatory condition, especially atopic dermatitis or enteropathy, you should work closely with your veterinarian to try to identify which foods make your dog’s symptoms worse, so that you can make diet choices to help manage their condition.

There is currently very little research comparing inflammation in dogs fed a whole (fresh) food diet versus a processed (commercial) diet. One small study suggests that feeding a whole food diet decreased general inflammation,¹³ but the information gained from this study is limited and requires further exploration.

One well-known nutrient that has been shown to reduce inflammation in dogs and people alike is omega-3 fatty acids. Commonly known as fish oil, omega-3 fatty acids can reduce inflammation in dogs with immune-related inflammatory conditions,¹⁵ and help manage inflammation associated with osteoarthritis.¹⁶

Reduce Your Dog’s Stress

Many dogs today are prone to anxiety and stress which can result in chronic inflammation in the body¹ if not managed properly. This anxiety often has behavioral causes and can be mitigated to some degree with proper training and management of the home environment.

Learn to recognize signs of stress in your dog. Work with your veterinarian, a veterinary behaviorist, and/or a trainer to help you learn to address any behavioral needs and to manage your dog’s home environment to minimize their specific stressors.

Reduce Pesticide and Herbicide Exposure

Repeated exposure to chemicals used in common pesticides and herbicides has been implicated in promoting chronic inflammation in the body.^3-5 When possible, avoid exposure to these chemicals by choosing lawn and garden care products that avoid these chemicals.

Reduce Air Pollution

Poor air quality is unfortunately something most of us are exposed to regularly, and one thing that we have little control over. To minimize exposure as much as possible, you can pay attention to air quality alerts and avoid spending time outdoors with your dog when air quality is at its worst.

Indoors, you can use an air purifier to help reduce toxins in your home, change furnace air filters regularly and avoid further pollution of indoor air with pollutants such as tobacco and combustion products. The Environmental Protection Agency provides an excellent guide to improving indoor air quality in your home.