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Yesterday’s post as part of the “A Salmonella Story” series I talked about the prevalence of bacteria in our world and how all meat, even yours is contaminated by the time you get it home. Today I’m going to talk about the dog’s digestive system and how it has been designed to handle nasty bacteria and other pathogens.
Digestion and Bacteria
A dog has a simple and relatively short gastrointestinal tract, about a 6:1 ratio, meaning the intestinal length is 6 times longer than the dog. Cat’s have an intestinal to body length ratio of 4:1 with some herbivores up to 20:1, very long!
A dogs stomach is simple compared to the stomach of a herbivore (cows have 4 stomach compartments), and since dogs evolved to eat easily digested animal protein, a complex digestive system as seen in the herbivore, is not required.
Digestion in Action
- Dog smells food & starts salivating
- Dog is presented with food
- Dog inhales food
- Digestion takes place
- Dog poops out unusable material from consumed food (which is a lot in a kibble fed dog)
In humans, chewing our food breaks it into smaller pieces that we can swallow and mixes it with the amylase an enzyme that begins the process of digesting carbohydrate. Since dogs are carnivores and have evolved to eat mainly animal protein, their saliva doesn’t contain amylase, but acts as a lubricant to help move food down the esophagus to the stomach. Another job of a dog’s saliva is to kill bacteria entering in its food.
Dogs weren’t designed to do a lot of chewing, their jaws are pretty much limited to up and down movement, good for cracking bones, tearing flesh and gulping down relatively large pieces of food, thanks to a fairly elastic esophagus.
A dogs stomach serves two purposes;
- It acts as a holding tank for mixing and storing large amounts of food.
- Exposes food to a highly concentrated solution of hydrochloric acid.
Dogs have a very acidic stomach with a pH of 1-2 (human stomach pH is between 4-5), making it capable of dissolving whole pieces of bone and snuffing out nasty bacteria not destroyed by saliva.
For the really hardy bacteria, the ones that are able to survive the environment of a dog’s highly acidic stomach, the rough ride isn’t over. The stomach contents (bolus) pass into the duodenum (small intestine), where the liver and pancreas deposit their enzymes; bile salts and bicarbonate. The pancreatic enzymes digest the cell walls of harmful bacteria and the liver’s bicarbonate contains powerful antimicrobial agents. Lysozyme another enzyme also wages war on the cell walls of bacteria.
Any bacteria that make it this far need to be able to attach to the wall of the small intestine, be able to move “upstream” so to speak, and be able to multiply rapidly to do their nasty work. If they can’t meet these criterion, they’re up sh*t creek without a paddle!
Intestinal Flora
Intestinal Flora are microorganisms that reside within the digestive tracts of animals and are generally thought of as having a symbiotic relationship with their host and are referred to as normal flora.
Normal flora discourages infection from outside pathogens by secreting antimicrobial substances preventing the bad guys from taking over and setting up shop.
Antibiotics kill off some of the good microorganisms upsetting the balance of the normal flora increasing the likelihood of further infection. This is usually why your doctor or veterinarian will usually recommend that you or your dog supplement with acidophilus or probiotics (good bacteria) while on antibiotics, this helps to maintain normal intestinal flora.
The carnivore’s colon is short to allow quick removal of waste, this combined with all of the digestive defences mentioned above, a healthy dog is well equipped to deal with salmonella and other pathogens.
In tomorrow’s post I’ll present some information to show just how difficult it can be for a dog to become infected with salmonella AND show clinical signs of illness from that bacteria.
Off Topic
Did you know that over 700 racing greyhounds have been injured at Wheeling (WV) Island Racetrack and Casino between January 2008 and September 2009. More than 1,000 dogs were prevented from racing because of injury or illness, and 62 dogs died or had to be euthanized during this period. Greyhound racing is wrong! Read more at PetNewsandViews.com
Disclaimer: The above information is not meant to be used to treat animals for medical problems nor should it take the place of proper veterinary medicine. For more information on raw canine diets, please contact a veterinarian who has experience with the diet and recommends it in their practice.
I'm a dog guardian to Sweety, my 15 year old Border Collie & Zeus a stray American Pit Bull Terrier that I rescued in October of 2009. I write about canine health and nutrition focusing mainly on topics relating to feeding a raw meaty bones diet.
