As an Ecosystem
Unfortunately, not all animals remain healthy throughout their lives. Accident, disease and often surgical or medical intervention will be necessary. In almost all cases, modification of the diet will assist recovery, slow the progression of incurable disease or improve the effect of organ dysfunction.
In some cases, adjustment of the quantities and proportions of nutrients is sufficient to improve your fur kids’ health. In others, a more complex manipulation is required when we need to consider not just a particular nutrient but a particular type of that nutrient and its effect on the whole body. To understand this, we need to take an overall view and realize that the digestive tract is not just a conveyor belt through the body, but is actually a complete ecosystem.
By definition, an ecosystem has two components – a community of organisms (the biotic component), and their habitat [Bacteria in the Gut: Friends and Foes and How to Alter the Balance] [ref]. The organisms interact with each other, often competing for space and food. They are also influenced by chemical and physical features of their environment (the abiotic component). The biotic component in the gut is formed of bacteria, fungi, protozoa, yeast and other organisms. Their numbers vary in different sections of the digestive tract, tending to increase in numbers distally (situated farthest from the middle and front of the jaw, as a tooth or tooth surface). The acidity of the stomach prevents high numbers there and rapid transit of food through the upper regions of the bowel normally discourages proliferation of organisms. However, in the large intestine, and in particular in the colon, high numbers of micro-organisms flourish. They are able to do so because the food residues are present in greater quantity and the flow rate is slower. Their effect on the body of the host animal is therefore greatest in the colon.
The composition of the gut flora is established within 2 to 3 weeks of birth (some research suggest it might be much later, between week 8 and 12) through contact with the mother and her environment. Once organisms colonize the gut, they are generally there for life. Their relative proportions can be influenced by the diet of your fur kid. Most of the research into the biotic component of the gastrointestinal ecosystem has concerned bacteria, the function and importance of the other micro-organisms being, as yet, not fully understood.
Gut bacteria fall into three groups – the good, the bad and the indifferent. To put this more scientifically, the beneficial species (bifidobacteria and eubacteria together with lactobacilli and other lactic acid bacterial), the pathogenic and putrefactive species (enterobacteria and clostridia) and neutral species (effectively the rest). These bacteria are part of the ecosystem, interacting with each other and the environment, but chiefly living their own lives and producing their own waste. This waste may be of use to the host animal, e.g. short-chain fatty acids which are used as a source for energy by the cells lining the colon, or may damage the host, e.g. toxic or carcinogenic products. If the beneficial bacteria can be increased in numbers, then the beneficial effect on the host will be greater. Greater numbers of these will also tend to crowd out the pathogens. This process is known as exclusion by competition. In doing so, it will reduce the harmful effects in the host. It is also possible that the beneficial bacteria may produce substances toxic to the pathogens and that beneficial bacteria boost the body’s ability to resist potential toxic effect of pathogens.
It is possible to manipulate these bacterial populations in two ways:
- Provide beneficial bacteria as a dietary supplement – also known as probiotics
- Provide substrates to encourage increase of beneficial bacteria – also known as prebiotics
We discuss The Gut in detail here, as a healthy gut is a healthy pet.
By definition, prebiotics are a type of non-digestible fiber compound. Just like other high-fiber foods, prebiotic compounds - including the kind found in foods like garlic, Jerusalem artichokes, jicama, dandelion greens and onions (for humans only) - pass through the upper part of the gastrointestinal tract and remain undigested, since the human and canine body can’t fully break them down. We discuss the importance of prebiotics in the diet.
Bacteria have a reputation for causing disease, so the idea of tossing down a few billion a day for your health might seem - literally and figuratively - hard to swallow. But a growing body of scientific evidence suggests that you can treat and even prevent some illnesses with foods and supplements containing certain kinds of live bacteria. We discuss the role of probiotics in your pets' health in more detail.
Your fur kids’ digestive system is different than a human's and therefore dogs (and cats) process and eat differently than us. This is important to know and understand so that you can feed your fur kids the correct diet and be aware when something goes wrong. We discuss this in more detail.