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Natural Canine Health Symposium

Why You Should Fast Your Dog

Photo:  Vic Neumann

Creating and maintaining a strong immune system is an important part of good health.  Toxins like vaccines, wormers, drugs and processed foods all present a challenge to the immune system, making our dogs more susceptible to disease and parasites.  Despite our efforts to the contrary, our dogs are exposed to a number of toxins every day including  hormones, vaccines and antibiotics in their meat, genetically modified and processed foods, hard metals and pesticides.

The dog’s digestive system does much more than simply digest food.  Approximately 80% of your dog’s immunity is found in his gut.  The dog’s intestinal tract has the ability to identify and destroy alien substances such as bacteria, viruses, parasites and chemical toxins.  It also has a built-in memory to recall the specific type of invader next time it presents a threat.

Additionally, the immune system is also an internal communication system comprised of a network of integrated cells to protect your dog. When there is a faulty connection, messages sent to the immune cells are misinterpreted and the ability to differentiate between your dog’s own cells and the invaders ceases and it begins to destroy healthy cells and tissues.  This presents as autoimmune disorders including allergies, arthritis, irritable bowel syndrome, food allergies, yeast overgrowth, liver disease and cancer.

Periodic house cleaning is essential for a strong immune system.  The burden of digestion demands all of the resources of the immune system.  If your dog is constantly digesting food, the immune system does not have the time or resources to stay in peak form.  Regular fasting can help the immune system detoxify years of toxic build-up and restore normal homeostatic balance.

Benefits of Regular Fasting

Elevated Macrophage Activity: Macrophages engulf and destroy bacteria, viruses and other foreign substances. They can ingest worn-out or abnormal body cells. Macrophages form an important first line of defense against harmful particles that have reached the body’s interior. Bolstering the body’s macrophages is often a course of treatment recommended for autoimmune diseases and even some forms of cancer.  Once the macrophages and other immune system components have essentially digested the body’s dead cells, the cells make their way through the bloodstream and eventually into the digestive system for final disposition. This means that the solid waste we call fecal matter is largely composed of dead cells sloughed off by the various organs and processed for elimination by macrophages. This process is dramatically increase during fasting as catabolism increases cellular breakdown to be utilized for fuel.

Increased Immunoglobulin Levels: Immunoglobulin is used to provide passive immunity to a variety of diseases such as immune mediated hemolytic anemia.

Increased Neutrophil Bactericidal Activity: Neutrophils engulf bacteria and other microorganisms. When a bacterium is engulfed by a neutrophil, a metabolic process within the granules produces hydrogen peroxide and a highly active form of oxygen called “superoxide”, which destroy the ingested bacteria.

Heightened Monocyte Killing and Bacterial Function: Monocytes are capable of ingesting infectious agents and other large particles. Monocytes usually enter areas of inflamed tissue or at sites of chronic infections.

Enhanced Natural Killer Cell Activity:Natural killer cells were first recognized in 1975. Researchers observed cells in the blood and lymphoid tissues that could kill tumor cells and cells infected with viruses. Most immunologists feel that natural killer cells play an important part in checking the growth of tumor cells and cells infected with some viruses.

Clinical Research

An experiment was conducted by Mark Mattson and his team at the National Institute on Aging. Mattson fed mice nothing every other day. The mice could eat as much as they wanted on the days in between, and they did. They pigged out. They ended up eating very nearly double what normal mice eat in a day.

But fasting every other day caused them to live longer and healthier lives. A lot longer and a lot healthier. The researchers don’t exactly know what to make of it. Mattson said, “We think what happens is going without food imposes a mild stress on the cells, and cells respond by increasing their ability to cope with more severe stress.” He said maybe it’s similar to what happens when you lift weights: You stress your muscles and they respond by growing stronger.

Near the very end of the study, they injected all the mice (those fasting every other day, and those eating a normal diet) with a toxin that damages the cells in the same part of the brain Alzheimer’s damages in humans (the hippocampus). Mattson and his team later looked at the brains of the mice and found that those that had been fasting every other day suffered less damage to their brain cells.

Recent studies suggest that such fasting may also promote recovery after acute spinal cord injury. Specifically, Drs. Ward Plunet and Wolfram Tetzlaff (photo), University of British Columbia randomized rats with experimental cervical injuries into control animals with free access to food, and those with access only every other day starting immediately after injury.

Compared to controls, fasted rats had improved functional recovery, smaller injury-site lesions, and increased neuronal regeneration.

The investigators concluded that EOD-fasting “can have benefits when initiated after the insult” … “Most importantly, intermittent fasting is a safe and simple multifaceted treatment that could be clinically implemented to improve functional recovery in patients.”

Tetzlaff noted: “We believe that a rigorous re-evaluation of nutritional guidelines for acutely injured patients is in order,” and are planning more basic-science experiments (toward a mechanistic understanding as well as a further corroboration of the principle in different SCI-lesion models). Hopefully this will provide the basis for clinical trials.”

The investigators think that fasting affects the body’s immune response, resulting in fewer, regeneration-blocking immune cells reaching the injury site.

Fasting your dog every week or so can yield tremendous health benefits.  Make sure he has plenty of water and only fast adult dogs:  puppies need a much more regular source of nutrition.


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  • 15 Responses to Why You Should Fast Your Dog

    1. JaySun

      Its good to give the digestive system a break for all animals. Including humans. This allows for healing and detoxing. If done properly it will lead to a longer healthier life.

    2. Carl

      K9 Coach, great points and totally agree – less domesticated habits are not a bad idea, obviously within reason.

      I’m new to reading upon this strategy as a detox, but it’s definitely something i’d try with my dog. I’m keen to do it myself, but I think i’d be whining much more than the dog.

    3. Debbie

      My vet has asked me to fast my dog after he has been getting sick a lot this week but it’s killing me with the whining… I don’t know how to get through the night!? Any suggestions on how to help him deal with not eating!?

      • Dogs Naturally Magazine

        How about giving him an antler to chew on? Or a little bit of kefir which will also help to build good flora in his gut.

    4. Jude

      everyone should be so healthy if you listen to what this article is saying. Humans and dogs alike. Its one day without food. It absolutely improves your overall health to fast once in a while. Dogs especially. Domestic dogs little constitutions have not evolved other the years just because we decided to let them sleep in our beds and eat bon bon ‘s all day. no….the way their digestive system works is the same way their ancestors digestive systems worked. When they had to hunt to survive – there were some days when they would not eat.
      I fast my dogs if they get into something nasty too like if they ate some rotten garbage or rotting carass (we live on an island and go to the woods and beach a lot)
      a raw food diet supplemented with organic coconut oil, spirulina, fresh clean water – will turn old arthritic dogs right around straight. add one day of fasting into that every other week or so and plenty of excercise? One healthy ass dog. thanks for this article.

      • walkthedog

        I totally agree. It’s the whole reason i googled the question. My thoughts were : don’t dogs in the wild go days at a time without eating? Of course they do. I think people personify their dog’s behavior and therefore, feed them like they think they need to be fed. At the end of the day, no matter how endearing they seem, it’s just a dog. They aren’t *that* smart or capable and should be fed and treated as such. Over and out.

    5. Mental and physical stimulation indeed should be part of any dog’s healthy lifestyle. Without these elements the “healthy” part goes away.

      I find the article on fasting interesting and tend to disagree with those above who are not seeing the point of this article. In fact I see those comments as the problem with most of our society, call it “domesticated” if you like, it has become an excuse to remain the way the majority has become… overweight, fat, obese or suffering from some sort of ailment. The thought of changing it up, diet included which fasting has a part in; people put big red flags up about… I’m mean really… the thought of change, especially when it’s a choice that is more difficult that taking a nice little pill, or continuing to eat comfort food (which is what people provide for dogs as well… it makes them feel better to feed the dog… it’s easy and provides serious wagging time)… it’s just that it also shortens their lives and it’s become apparent on the people side too.

      Since our dogs are living shorter lives on average then decades past… perhaps a little less “domesticated” habits are a good option to look at! Same for people… less processed food, more whole food, and less of it is a good thing… but that may sound less “domesticated” than we’ve become in our comfortable super sized fast food ways too.

      Aloha Wags!

    6. BJG

      Who is the author of this article? Why would the author not put his/her name on the page (the photographer did!)?
      Who is Matt Mattson and what are his qualifications? Is he an MD, PhD, DVM?
      I think it’s a big leap from a rat study to advising pet owners to fast their dogs.

      • there is a link abot contact the author

    7. DCF

      I tend to agree with you. I still do not see the point in fasting a dog and they have failed to show me any reason I should feel differently.

      • Mich-H

        The article showed you no reason ? It clearly states the benefits should you decide to fast . You may need to read it more carefully.

    8. Diane

      That is very misleading. First of all, fasting is normal in wild dogs and not in domestic dogs. Domestic dogs are stressed by missing meals because nearly all people do not give their dogs even remotely enough physical or mental stimulation. When taking away their regular mealtime, a domestic dog is stressed. It’s far better to feed a domestic dog less and to feed them a species appropriate diet. That is the key to better health for a DOMESTIC dog. In the wild, canids are busy occupying themselves with the activity and mental stimulation of seeking out prey and hunting or foraging for their next meal. Domestic dogs instead are nearly totally idle. People should be far more concerned about meeting a dogs proper activity and mental stimulation levels than fasting.

      • Lou

        You are right Diane, it does stress the dogs, but like the article says that is the whole point of fasting them. The stress, which should be no longer than 24 hours, strengthens their immune systems. Remember the weight-lifting analogy. Yes, owners do not give their dogs as much mental and physical stimulation as they need, this is true! But that does not discredit the potential health benefits of fasting. Unexercised dogs could probably benefit more from fasting than active dogs. Humans are “domesticated”, but we still benefit from fasting too!

      • my dogs have mental and physical activity, I tried fasting them and they throw up yellow bile,


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