The effect of digestion and the microbiome on skin and coat.

The current flavour of the month when it comes to any discussion regarding nutrition, skin and coat health, digestion and the function of the gut is a wholehearted examination of the relevance of the microbiome. But what is the microbiome and what is all the fuss about?

The gut microbiome is the collection of bacteria, fungi and viruses that inhabit the gastro-intestinal tract (gut) of the dog, and is not only responsible for many aspects of digestion, but influences areas such as mood, disease resistance and wellbeing. The number of organisms that inhabit the gut is quite amazing; there are more than a trillion of them and over a thousand species, with the diversity of species in the microbiome being greater than that found in a rainforest. Some would claim “the microbiome should be classed as an organ”, or “our pets are 90% bacteria and 10% dog”, but these statements are a little over the top. The reality is the animal is approximately 50% animal and 50% microorganisms with each requiring the other for their survival. In other words, the gut microbiome and the animal enjoy the ultimate symbiotic relationship.

The main areas that are influenced by the microbiome are:

1. The immune system – up to 90% of the dog’s immunity comes from the microbiome working in association with the mucous membrane lining of the gut. It is in this lining, known as “gut associated lymphoid tissues”, where lymphocytes, T and B cells reside. These cells are the mainstay of the immune system and are vitally important in providing immunity for the animal.
2. Mood – whilst we commonly think of the brain as being in the skull, what is not so commonly known is there is a thin layer of brain cells embedded in the gut tissue and extending the full length of the gastrointestinal tract. Called the enteric system, these neurons are connected to the brain by the vagus nerve, which is a bit like a busy telephone line with messages zooming backwards and forwards all day long. But it’s via the vagus nerve that the gut microbiota appears to have a direct line to the brain, and can control mood by producing hormones such as the feel-good hormone dopamine and the neurotransmitter serotonin. Similarly, if your dog is consuming a disproportionate quantity of one foodstuff, such as sugars, the sugar loving organisms will multiply and dominate, with the resultant craving (or fussy eating syndrome) for that type of food. In one remarkable experiment with mice, researchers were able to show that mice infected with Toxoplasma gondii bacteria became strangely reckless and were strongly attracted to cat urine. When the bacterial balance was restored, the mice resumed their normal, cautious behaviour. It seems there is little doubt the Toxoplasma gondii bacteria were hell bent on populating the cat’s microbiome by modifying the behaviour of the mice. Sounds far-fetched doesn’t it, but it is further confirmation of the “gut-brain axis” which is a popular subject of current research.
3. Protection from disease causing pathogens – a healthy microbiome protects the dog by competitively excluding harmful bacteria and viruses. By completely colonising the gut, the good organisms out-compete the bad guys for food and starve them out. Full colonisation also severely limits the opportunities for the pathogens to gain a foothold in the gut from which to populate and expand.
4. Forms a protective barrier – in the same way as pathogens are excluded, the microbiome can form a protective layer that inhibits absorption of harmful substances such as toxins, carcinogens, allergens and drugs, with these potentially harmful substances simply being eliminated from the body in the faecal waste.
5. Assists with digestion whilst producing additional nutrients – by far the greatest contribution the microbiome makes to the host dog is its assistance in releasing nutrients from the food, as well as producing other essential nutrients at the same time. One example of this is the production by the microbiota of enzymes to assist in the breakdown of the food, without which much of the nutrition contained in the food would not be able to be absorbed into the blood stream. Once the nutrient breakdown is completed the microbiome actually assists in the transfer of the nutrients from the gut to the blood stream. Other members of the microbiome are responsible for the production of vitamins, particularly B vitamins, and whilst these are usually present in the food, the balance of the dog’s requirement is produced in the gut. Another vital area is the fermentation of fibre by Bacteroidetes to produce, amongst other substances, butyrate. Butyrate is an immensely important chemical in gut function because it not only helps to control the growth of cells in the wall of the gut and thus protects against bowel cancer, but acts as an anti-inflammatory. Whilst inflammation is the bodies key defence mechanism against infection, long term, low level inflammation has a negative effect on the body and is a precursor to many sensitivity and allergy issues in dogs.

This means the starting point in any discussion regarding skin and coat health must be the microbiome. The presence of long term, low level gut inflammation causes the immune system to dramatically increase its level of activity, which in turn results in the immune system attacking simple compounds such as pollen and gluten. These attacks are an indication that the microbiome in its present state of diversity is ignorant to what substances are threatening, compared to the substances that pose no threat and can be left alone. It is also an indication that many of the species of organisms that evolved with the animal over millions of years have been lost, and with that loss is the microbiome’s knowledge as to which substances pose the real threat. This loss of beneficial organisms has been exacerbated through the use of antibiotics, whilst stress, pollutants and highly processed foods all make a contribution.

…the starting point in any discussion regarding skin and coat health must be the microbiome.

Unfortunately, we are seeing more and more dogs displaying skin sensitivity problems, with these problems appearing earlier in the dog’s life. Quite young pups are now regularly appearing with compromised skin and coat health, which suggests this loss of microbiome diversity is continuing unabated.

So how do we reverse this situation and restore good health to our pets?

• Change the food – at LifeWise we bang on a lot about only using ingredients in the food which are sympathetic to the dog. By that we actually mean the ingredients are required to foster a healthy microbiome, and those ingredients are present in the food at levels that actually encourage the correct balance of microbiota to restore and maximise the symbiotic relationship between the microbiome and the animal.

A very good example of this is the discussion that centres around the use of grains in pet food. More and more products are appearing on the market boasting a “grain free” status, with proponents of grain free diets making the claim that “you never see a dog chewing on a head of wheat”. Whilst this may be true, it doesn’t take into consideration the evolving status of our domesticated dogs that are now quite capable of digesting starch, plus the fact that resistant starch is also a valued nutrient for organisms in the large intestine where it is fermented to produce butyrate. The other interesting snippet regarding starch is that all dry foods contain starch, whether they be grain free or grain based. Grain free foods typically rely on carbohydrate sources such as potato, pea flour and tapioca to provide the starch with which to bind the food together to make a crunchy kibble, whereas foods containing grain use rice or groats or similar for their starch supply. The key factor here is how much starch is in the food in total, and whether it is balanced to the needs of the microbiome. It goes without saying that excessive amounts of starch, or starch in the wrong balance, can cause low level gut inflammation which as we now know is a precursor to skin and coat issues in our pets.

• Feed a probiotic – the term “probiotic” was first coined by a US researcher to describe the effect of infusing the gut with live, beneficial bacteria. The word soon gained general use as a noun, and is now defined by the World Health Organisation as “live microorganisms, which when administered in adequate amounts, confer a health benefit on the host.”Today, there are many probiotic supplements on the market for a variety of applications not only in our dogs, but for humans and as a useful additive in the nutrition of many other domesticated animals.

Probiotics are available in a number of forms; powder, tablets, liquids or gels. Regardless of the form of the probiotic, it should always be remembered that we are dealing with live bacteria. In the case of powders and tablets, the bacteria are in a freeze-dried form, and whilst being shelf stable, longevity is enhanced through storage in the refrigerator. They are far more stable than the gel or liquid forms which have a relatively short shelf life. Next time you are in the supermarket, check the “use by date” on the yoghurt, and that will give you a good indication of how long these liquid types of probiotics will keep.

The benefits of feeding probiotics are universally accepted as being helpful in a number of situations including:

1. Disease or sensitivity issues such as skin and coat disorders.
2. Stress situations – feedlot cattle are often fed probiotics on arrival to combat the stress disorder “feedlot fever”.
3. After illness to restore gut motility following antibiotic treatment.
4. Dietary related issues that require an improvement to digestion.
5. As a digestive aid in aged dogs where digestive efficiency has declined.
6. To assist an animal that is suffering from parasite infection.

Of course, we now know all of these problems are associated with disruptions to the balance of the microbiome, so it shouldn’t come as a big surprise that seeding the gut with beneficial bacteria will make a difference to the health and wellbeing of our dogs.

Many pet owners have resorted to using yoghurt as an emergency probiotic, but here at LifeWise we prefer to feed any one of the preparations that are formulated specifically for animals. Whilst the microbiome of dogs, cats and humans are quite similar, a wider range of bacteria and yeast appear to be superior to the use of the more limited range found in natural yoghurt and human probiotic supplements. Examples of the type of bacteria to look for when contemplating purchasing a probiotic supplement are:

1. Lactobacillus acidophilus
2. Lactobacillus plantarum
3. Lactobacillus casei
4. Lactobacillus salivarius
5. Lactobacillus rhamnosus
6. Lactobacillus brevis
7. Enterococcus faecium
8. Bifidobacterium bifidum
9. Bifidobacterium lactis
10. Bifidobacterium breve
11. Streptococcus thermophilus

It would be unusual to find all eleven of these strains in the one preparation, but a good mix of any of the above should be suitable for your dog.

• Clean up the dog’s environment, both the internal and the external environment. As touched on earlier, chemicals ingested internally or chemicals in the dog’s surrounding environment can have a detrimental effect on the microbiome. Problematic chemicals and medications include:

1. Antibiotics – these medications do not discriminate between good bacteria and bad bacteria, and whilst being essential in the treatment of bacterial disease, antibiotics also devastate the population of the microbiome. Feeding a probiotic supplement together with natural food sources that promote a healthy biome are essential following a course of medication.
2. Shampoos and conditioners – excessive use of shampoos and conditioners, or the use of the wrong types (for example, using human shampoo rather than a canine shampoo) can decimate the skin microbiome, which is closely connected to the gut microbiome via what is called the skin-gut axis. In other words, changes in one microbiome affects the other, and the negative impact on one will translate to the other.
3. Parasite control medications – flea, tick and worm medications can have a significant effect on the microbiome, with the resultant modification of the microbiota balance being the precursor to skin and coat problems. Heart worm medication, particularly the injectable form which is administered annually, is a particularly harsh chemical that can cause an over-active immune system to go into meltdown. Here at LifeWise we never inject for heartworm, and aim to use more natural or gentler methods of administering anthelmintic treatments.
4. Pollutants – abound in our environment from air born pollutants to household cleaners and disinfectants. Many of these chemicals are blamed for the decline in microbiome diversity, and their avoidance where possible can only assist in maintaining the health and wellbeing of our pets.
5. Natural allergens – many of the dogs we see with skin conditions show seasonal allergy to grasses and pollen. For dogs suffering this type of problem a quick and easy aid in their treatment is to wipe them down with a damp cloth on returning home from a walk. Simply removing the offending irritants from the feet, toes, muzzle and chest can be a great help whilst we work to get the diet, blood nutrient levels and the microbiome back in balance.
6. Stress – we are not the only ones to suffer stress related disorders. Our pets can also suffer, and the microbiome is probably the first part of the body system to be affected. Stress comes in a number of forms for our canine companions, with one of the most common being nutritional stress from a poorly balanced diet. Other subtler forms of stress can result from the dog not having a clearly defined chain of command within the pack (dogs think of their human family as a pack and the rules of the pack must apply) whereby the dog assumes a leadership/protector attitude because of a perceived lack of leadership from any other member of the pack. There is no such thing as equality in a dog pack; each member assumes their position in the hierarchy through their ability to lead or be led. Other stresses such as separation anxiety can also impact upon the health and wellbeing in the same way as previously discussed.

So far, this whole discussion has centred on the relevance and impact of the gut microbiome on the health and wellbeing of our dogs. But, this is only half of the story.

Whilst it follows that sympathetic ingredients in the food will give rise to a healthy and well-balanced microbiome, we still have to ensure the nutritional balance within the food accurately matches the dog’s particularly needs relative to its age and stage of physiological development.

To achieve this outcome, LifeWise food ingredients are analysed for their essential nutrient content before the ingredients are mixed and matched to provide the perfect balance of essential nutrients in the correct ratios to one another. This method, known as nutrient ramping (see the separate article Nutrient Ramping) ensures the correct levels of nutrients are available for use in the body proportionally to the rate of energy expenditure.

The thrust of this nutritional approach is to identify and optimise each process in delivering essential nutrients to the body by optimising each stage of the entire process.

What all this means is that the maintenance of good health and wellbeing is not just a one-dimensional process. It is the sequence of events whereby the ingredients are matched to the microbiome whilst the nutrients are matched to the animal. In other words, it is like a team effort with each member of the team optimised for the best possible outcome for both you and your dog, so it’s a bit like turning a team of champions into a champion team!

Hopefully, this article has shed a little light on an otherwise dark and sometimes smelly area of canine nutrition. Should you require additional information, or would like to comment on any of the above, please drop us a line on the contact form below.