By Paula Fitzsimmons
A healthy digestive system is essential to your dog’s well-being. The digestive system serves many important functions: it takes in food, absorbs nutrients, maintains fluid and electrolyte balance, and gets rid of waste, says Dr. Carolyn Jochman, a veterinarian with WVRC Emergency & Specialty Pet Care in Waukesha, Wisconsin.
It also covers a lot of area. “The digestive tract includes the oral cavity (salivary glands, tongue, teeth), esophagus, stomach, small and large intestine, liver, pancreas, rectum, and anus,” she says.
The canine digestive system isn’t the most glamorous topic, but understanding how it works puts you in a better position to determine if your dog is sick and needs to be seen by a vet. It can also guide you in making decisions that will enhance her health. Added bonus: If you’re into anatomy, the canine digestive system is pretty cool.
1. Dogs Get Heartburn, Too
In the fasted state, stomach acids are very similar in people and dogs, says Dr. David Brummer, a veterinarian with Orchard Park Veterinary Medical Center in Orchard Park, New York. After eating, however, dogs produce more acid than we do, he says.
Our similarities mean that “dogs and people benefit from the same antacids.” But before giving your dog an over-the-counter antacid, talk to your veterinarian and be aware of potential drug interactions, side effects, and warnings.
But more stomach acid doesn’t translate to letting your dog eat potentially-contaminated foods. “Dogs are no less sensitive to food poisoning (bacterial contamination) than are people,” he says. For example, “The practice of feeding raw meat to dogs carries a demonstrated risk of food poisoning.”
2. Human and Canine Digestive Systems Share Other Similarities
“Dogs have a small intestine that occupies about 25 percent of the total gastrointestinal volume, which is consistent with other omnivores, including people,” Jochman says. “The small intestine of a cat, a true carnivore, occupies only 15 percent.”
On average, food moves through the canine stomach a bit slower than ours, but food movement through the intestines is a little faster, says Brummer, who is board-certified in internal medicine.
Gastrointestinal transit time is six to eight hours for dogs, while in people it’s between 20 and 30 hours, Jochman adds.
3. Dogs Can’t Chew Side to Side
You’ve probably noticed that your dog can’t chew side to side. “The dog’s jaw only allows for up and down motion when chewing,” Jochman explains. “People also have side-to-side movement that allows more grinding of food.”
The difference probably has to do with our historical diets. The wolf-like ancestors of dogs ate mostly meat that could be easily ripped and swallowed, but people also relied on gathering or farming plant material that required more chewing.
4. Most Dogs Can Digest and Absorb Carbs
But modern dogs are considered omnivores, just like we are. They originally ate a carnivorous diet in the wild, “but since they have been domesticated, adaptions have been made that allow them to digest and utilize plant-based nutrients,” Jochman explains.
True carnivores, like cats, have a higher nutritional requirement for taurine, arachidonic acid, and certain vitamins, which are available in animal fat and protein sources. “Omnivores don’t have a higher requirement for these and create their own arachidonic acid from vegetable oils,” he says.
“Most normal dogs have no difficulty digesting and absorbing carbohydrates,” Brummer adds. So, “there is no benefit to feeding grain-free diets to normal dogs.”
5. Cholesterol Doesn’t Impact a Dog’s Health
Your doctor may advise you to lower your cholesterol level, but you won’t hear the same concerns echoed at the vet’s office. “Cholesterol does not have the same effect on their heart, and their digestive systems are designed to accommodate animal fat,” Jochman says.
Dogs also don’t have the same issues with colon cancer, says Dr. Joseph Wakshlag, a board-certified veterinary nutritionist at Cornell University College of Veterinary Medicine in Ithaca, New York. “So the idea that eating foods high in soluble fiber or low in saturated or trans-fats will provide any health benefit is really unknown at this point.”
Vets say one of the keys to health is keeping your dog at a healthy weight. “Obesity is related to exacerbation of many health problems in dogs and is our number one battle,” Wakshlag says. “If there is any one thing that we can do, it is talk to our vets about how to curb obesity.”
6. Digestive Problems Are Relatively Common in Dogs
Gastrointestinal diseases account for about 10 percent of veterinary visits, says Dr. Jan Suchodolski, associate professor and associate director for microbiome sciences of the Gastrointestinal Laboratory at Texas A&M University, in College Station, Texas. “Diarrhea is one of the most frequent clinical signs,” he says. “Abnormal stool may also be a first symptom of a more systemic disease process, such as kidney, liver, and some endocrine disorders.”
Vomiting is also a common symptom. An acute bout may resolve itself over a day or two—vets will often recommend a short, 12-hour period of fasting to “rest” the GI tract, followed by a bland diet, Jochman says. “But when the clinical signs continue or are especially severe, testing is often recommended to attempt to find out what may be causing the distress,” she says.
Imbalances with other organs, such as the kidneys, can also cause gastrointestinal signs. “So it is important to see your vet to determine the best treatment for your dog,” Jochman adds.
7. Your Dog’s Poop Tells a Lot About Her Health
You can learn a lot about your dog’s health by studying her poop (an unpleasant, but necessary task). “There are a variety of causes for abnormal stool,” says Suchodolski, who is board-certified in immunology. “Most episodes of acute onset diarrhea are typically self-limiting within a few days, as dietary indiscretions are a frequent cause.”
Parasites, bacteria, and viruses may also cause diarrhea, he says. “Depending on the underlying cause, the animal may or may not need appropriate treatment for the infectious agent. If diarrhea persists for several days, and/or there is blood in the stool, the animal should be examined by a veterinarian who can determine the most appropriate course of treatment.”
On the other hand, if your dog isn’t pooping and is straining to defecate, she may be constipated, which if prolonged, may cause serious health issues, Suchodolski says.
One important takeaway is to contact your vet if you notice anything suspicious. “Even short episodes of diarrhea or constipation that occur periodically, especially in combination with other signs, like weight loss and loss of appetite, may indicate a more complicated disease process,” he says.
Another key point is that you regularly monitor your dog’s poop habits. “It is important for the owner to daily monitor how often the animal defecates and the consistency of the stool,” Suchodolski says. “There is some variation between animals and also variation from day to day, with some animals having consistently softer stools or harder stools than others. But generally, with time, the owners should be able to establish what’s normal for their animal.”