There is some debate as to whether domestic dogs should be classified as omnivores or carnivores by diet. The classification in the Order Carnivora does not necessarily mean that a dog’s diet must be restricted to meat unlike an obligate carnivore, such as the cat family with its shorter small intestine, a dog is neither dependent on meat-specific protein nor a very high level of protein in order to fulfill it basic dietary requirements. Dogs are able to healthily digest a variety of foods including vegetables and grains, and in fact dogs can consume a large portion of these in their diet.
Wild canines not only eat available plants to obtain essential amino acids, but also obtain nutrients from vegetable matter form the stomach and intestinal contents of the herbivorous prey, which they usually consume. Domestic dogs can survive healthily on a reasonable and carefully designed vegetarian diet, particularly if eggs and milk products are included. Some sources suggest that a dog fed on a strict vegetarian diet without L-carnitine may develop dilated cardiomyopathy, however, L-carnitine is found in many nuts, seeds, beans, vegetables, fruits, and whole grains. In the wild, dogs can survive on a vegetarian diet when animal prey is not available. Observation of extremely stressful conditions such as the Iditarod Trail Sled Dog Race and scientific studies of similar conditions has shown that high protein (approximately 40%) diets including meat help prevent damage to muscle tissue in dogs and some other mammals. This level of protein corresponds to the percentage of protein found in the wild dog’s diet when prey is abundant, higher level or protein seem to confer no added benefit.
Dogs frequently eat grass, which is a harmless activity. Explanations abound but rationales such as that it neutralizes acid or that dog eat grass to induce vomiting to remove unwanted substances from their stomachs, are the best educated guesses. Dogs do vomit more readily than humans, as part of their typical feeding behavior of gulping down food then regurgitating indigestible matter such as bones or fur. This behavior is typical of pack feeding in the wild, where the most important thing is to get as much of the kill as possible before others consume it all. Individual domestic dogs, however, may be very “picky” eaters, in the absence of this social pressure. Dogs may also appear to eat grass when they are running the blades through their mouths to gather information. Their sense of small and taste may act together to detect if other animals have walked through there are or urinated on the grass.
Dangerous Substances for Dogs and Puppies
Human Food Some foods commonly enjoyed by humans are dangerous to dogs, including chocolate (Theobromine poisoning), onions, grapes and raisins, some types of gum, certain sweeteners and Macadamia nuts. The only known dangerous substance in chocolate is cocoa, so the danger of white chocolate is uncertain. The acute danger from grapes and raisins was discovered around 2000, and has slowly been publicized since then. The cause is not known. Small quantities will induce acute renal failure. Sultanas and currants may also be dangerous. Cooked bones are dangerous for dogs, because the heat of cooking changes their chemical and physical properties so that they cannot be chewed properly. As a result they may splinter into jagged shards that resist digestion. Alcoholic beverages pose comparable hazards to dogs as they do to humans, but due to low body weight and lack of alcohol tolerance they are toxic in much smaller portions.
Plants Plants such as caladium, dieffenbachia and philodendron will cause throat irritations that will burn the throat going down as well as coming up. Hops are particularly dangerous and even small quantities can lead to malignant hyperthermia. Amaryllis, daffodil, english ivy, iris, and tulip (especially the bulbs) cause gastric irritation and sometimes central nervous system excitement followed by coma, and, in severe cases, even death. Ingesting foxglove, lily of the valley, larkspur and oleander can be life threatening because the cardiovascular system is affected. Yew is very dangerous because it affects the nervous system. Immediate veterinary treatment is required for dogs that ingest these.
Household Poisons Many household cleaners such as ammonia, bleach, disinfectants, drain cleaner, soaps, detergents, and other cleaners, mothballs and matches are dangerous to dogs, as are cosmetics such as deodorants, hair coloring, nail polish and remover, home permanent lotion, and suntan lotion. Dogs find some poisons attractive, such as antifreeze (automotive coolant), slug and snail bait, insect bait, and rodent poisons. Antifreeze is insidious to dogs, either puddled or even partly cleaned residue, because of its sweet taste. A dog may pick up antifreeze on its fur and then lick it off.
Animal Feces Dogs occasionally eat their own feces, or the feces of other dogs and other species if available, such as cats, deer, cows, or horses. This is known as coprophagia. Some dogs develop preferences for one type over another. There is no definitive reason known, although boredom, hunger, and nutritional needs have been suggested. Eating cat feces is common, possibly because of the high protein content of cat food. Dogs eating cat feces from a litter box may lead to Toxoplasmosis. Dogs seem to have different preferences in relation to eating feces. Some are attracted to the stools of deer, cows, or horses.
Other Risks Human medications may be toxic to dogs, for example paracetamol/acetaminophen (Tylenol). Zinc toxicity, mostly in the form of the ingestion of US cents minted after 1982, is commonly fatal in dogs where it causes a severe hemolytic anemia. Some wet dog and cat food was recalled by Menu Foods in 2007 because it contained a dangerous substance.