Dog food
Dog food is food specifically formulated and intended for consumption by dogs and other related canines. Dogs are considered to be omnivores with a carnivorous bias. They have the sharp, pointed teeth and shorter gastrointestinal tracts of carnivores, better suited for the consumption of meat than of vegetable substances, yet also have 10 genes that are responsible for starch and glucose digestion, as well as the ability to produce amylase, an enzyme that functions to break down carbohydrates into simple sugars - something that carnivores lack. Dogs evolved the ability living alongside humans in agricultural societies, as they managed on scrap leftovers from humans.
Dogs have managed to adapt over thousands of years to survive on the meat and non-meat scraps and leftovers of human existence and thrive on a variety of foods, with studies suggesting dogs' ability to digest carbohydrates easily may be a key difference between dogs and wolves.
In the United States alone, the dog food market is expected to reach $23.3 billion by 2022.
History
Prior to being domesticated, dogs, being canines, fended for themselves and survived on a carnivorous diet. After adapting them for protection, work, and companionship, people began to care at least in part for their nutritional needs. The historic record of this changing approach dates back at least 2,000 years.In 37 BCE, Virgil talks about the feeding of dogs in his Bucolics:
Around 70 CE, Columella wrote his book On Agriculture in which he addresses the feeding of dogs:
In the Avesta, written from 224 to 651 CE, Azura Mazda advises:
In France, the word pâtée began to appear in the 18th century and referred to a paste originally given to poultry. In 1756, a dictionary indicates it was made of a mixture of bread crumbs and little pieces of meat given to pets.
In 1781, an encyclopedia mentioned an earlier practice of removing the liver, heart, and blood of a downed stag and mixing it with milk, cheese, and bread, and then giving it to dogs.
In 1844, the French writer, Nicolas Boyard, warned against even giving tallow graves to dogs, though the English favored them, and suggested a meat-flavored soup:
In England, care to give dogs particular food dates at least from the late eighteenth century, when The Sportsman's dictionary described the best diet for a dog's health in its article "Dog":
In 1833, The Complete Farrier gave similar but far more extensive advice on feeding dogs:
It was not until the mid-1800s that the world saw its first food made specifically for dogs. An American electrician, James Spratt, concocted the first dog treat. Living in London at the time, he witnessed dogs around a shipyard eating scraps of discarded biscuits. Shortly thereafter he introduced his dog food, made up of wheat meals, vegetables and meat. By 1890 production had begun in the United States and became known as "Spratt’s Patent Limited".
In later years, dog biscuit was sometimes treated as synonymous with dog food:
Canned horse meat was introduced in the United States under the Ken-L Ration brand after World War I as a means to dispose of excess horses no longer needed for the war. The 1930s saw the introduction of canned cat food and dry meat-meal dog food by the Gaines Food Co. By the time World War II ended, pet food sales had reached $200 million. In the 1950s Spratt's became part of General Mills. For companies such as Nabisco, Quaker Oats, and General Foods, pet food represented an opportunity to market by-products as a profitable source of income.
Commercial varieties
Most commercially produced dog food is made with animal feed grade ingredients and comes dry in bags or wet in cans. Dry food contains 6–10% moisture by volume, as compared to 60–90% in canned food. Semi-moist products typically run 25–35%. Isotopic analysis of dog food in the Brazilian market have found that they are basically made of maize and poultry by-products.Dry food
Dry dog food usually consists of bagged kibble that contains 3-11% water. It makes up the vast majority of pet foods.Dry food is both convenient and typically inexpensive, with over $8 billion worth being sold in 2010 – a 50% increase over just seven years earlier.
Manufacturing process
Dry food processing is popular in the pet food industry, as it is an efficient way to supply continuous production of feed in many varieties. It is energy efficient, allows for large amounts of feed to be used, and is cost effective.To make dog kibble, a process known as extrusion is done. A simple extruder consists of a barrel, helical screws, and a die. Feed ingredients are solid at room temperature; therefore, the extrusion process of these ingredients requires a temperature above 100 degrees Celsius, achieved by the use of steam, hot water, or other heat sources in order to soften or melt the mixture and allow for fluidity through the barrel. During the extrusion process, the high amounts of pressure applied to the mixture forces it to enter through the die before exiting the extruder completely, where it is cut to its desired size by a rotating fly knife.
Unfortunately, the extrusion process actually denatures some of nutritional elements of the food. Taurine deficiency has been found in dogs and cats fed extruded commercial diets. Not usually considered an essential nutrient for dogs, taurine is plentiful in most whole meats, whether raw or cooked, but is reduced in extruded diets. Taurine deficiency could also be due to the use of rendered, highly processed meat sources that are low in taurine. Regardless of the cause, taurine is now artificially supplemented back into the diet after processing in the production of most commercial pet food.
Wet food
Wet or canned dog food usually is packaged in a solid or soft-sided container. Wet food contains roughly 60-78% water, which is significantly higher in moisture than dry or semi-moist food. Canned food is commercially sterile ; other wet foods may not be sterile. Sterilizing is done through the process of retorting, which involves steam sterilization at 121 degrees Celsius. A given wet food will often be higher in protein or fat compared to a similar kibble on a dry matter basis ; given the canned food's high moisture content, however, a larger amount of canned food must be fed in order to meet the dog's required energy needs. Grain gluten and other protein gels may be used in wet dog food to create artificial meaty chunks, which look like real meat. This food is usually used for old dogs or puppies.Manufacturing process
After ingredients are combined, they are placed in a tank at the end of a canning machine. From there, the mixture is forced through an opening and onto a metal sheet, forming a thickness of 8 to 12mm. Next, the mixture is heated to thoroughly cook the ingredients. Heating can be done through the means of ovens, microwaves or steam heating. The sheet containing a layer of feed is passed through the heat source that displays heat to the top and bottom of the tray, allowing the internal temperature to reach 77 degrees Celsius at a minimum. Once cooked, this mixture can be directly placed into cans to form a loaf or it can be cut into “meaty” pieces for chunks and gravy formulas.Semi-moist food
Semi-moist dog food is packaged in vacuum-sealed pouches or packets. It contains about 20-45% water by weight, making it more expensive per energy calorie than dry food.| Advantages | Disadvantages |
| High palatability | Contains artificial color, chemical preservatives, and chemical flavor enhancers |
| Convenient | Contains higher levels of sodium and sugar |
| Energy-dense | Expensive |
Most semi-moist food does not require refrigeration. However, some of the more well-known choices are "Freshpet" products, which are pasteurized meals requiring refrigeration. They are lightly cooked and then quickly sealed in a vacuum package. This type of dog food is extremely vulnerable to spoiling if not kept at a cool temperature and has a shelf life of 2–4 months, unopened.
Alternatives
Some alternatives to traditional commercial pet foods are available. Many companies have been successful in targeting niche markets, each with unique characteristics. Some popular alternative dog food types are:- Dehydrated or freeze-dried meals come in raw and cooked forms. Products are usually air-dried or frozen, then dehydrated to reduce moisture to the level where bacterial growths are inhibited. The appearance is very similar to dry kibbles. The typical feeding methods include adding warm water before serving. There is some concern of nutrients, such as vitamins, being lost during the dehydration process.
- Specialty ‘‘small batch’’ type feeds sold through specialty or online stores generally consist of some form of cooked meat, ground bone, pureed vegetables, taurine supplements, and other multivitamin supplements. Some pet owners use human vitamin supplements, and others use vitamin supplements specifically engineered for dogs.
Contents
Less expensive dog foods generally include less meat and more animal by-products and grain fillers. Proponents of a natural diet criticize the use of such ingredients, and point out that regulations allow for packaging that might lead a consumer to believe that they are buying natural food, when, in reality, the food might be composed mostly of ingredients such as those listed above. More expensive dog foods may be made of ingredients suitable for organic products or free range meats. Lamb meal is a popular ingredient.
According to the Association of American Feed Control Officials, animal by-products in pet food may include parts obtained from any animals that have died from sickness or disease, provided they are rendered in accordance to law. Cow brains and spinal cords not allowed for human consumption under federal regulation 21CFR589.2000 due to the possibility of transmission of BSE are allowed to be included in pet food intended for non-ruminant animals. In 2003, the AVMA speculated changes might be made to animal feed regulations to ban materials from "4-D" animals – those who enter the food chain as dead, dying, diseased or disabled.
Quality, digestibility and energy density
There are a few key components to consider when evaluating dietary needs. These factors include the quality and digestibility of the protein provided in the diet, as well as the composition of the amino acids included, and finally the energy density provided in the diet. Diets containing proteins that are high in quality, composition, and digestibility require less of that protein to be present. The same can be said in regards to the energy density. In contrast, high-protein diets will provide excess protein content after meeting maintenance demands; this can therefore lead to the protein being utilized in fat and energy storage. This ultimately increases the risk for developing obesity and other health related issues. However, higher protein in the diet helps reduce lean body mass loss, but will not lead to an increase in size of muscle unless paired with resistance exercises or anabolic steroids under maintenance conditions.Labeling
In the United States, dog foods labelled as "complete and balanced" must meet standards established by the Association of American Feed Control Officials, either by meeting a nutrient profile or by passing a feeding trial. The Dog Food Nutrient Profiles were last updated in 2016 by the AAFCO's Canine Nutrition Expert Subcommittee.Critics argue that due to the limitations of the trial and the gaps in knowledge within animal nutrition science, the term "complete and balanced" is inaccurate and even deceptive. An AAFCO panel expert has stated that "although the AAFCO profiles are better than nothing, they provide false securities."
Certain manufacturers label their products with terms such as "premium", "ultra premium", "natural", and "holistic". Such terms currently have no legal definitions and are not regulated. There are also varieties of dog food labeled as "human-grade food." Although no official definition of this term exists, the assumption is that other brands use foods that would not pass US Food and Drug Administration inspection according to the Pure Food and Drug Act or the Meat Inspection Act.
The ingredients on the label must be listed in descending order by weight before cooking. This means before all of the moisture is removed from the meat, fruits, vegetables and other ingredients used.
Types of diets
Raw dog diet
Raw feeding is the practice of feeding domestic dogs, cats and other animals a diet consisting primarily of uncooked meat, edible bones, and organs. The ingredients used to formulate raw diets can vary. Some pet owners choose to make homemade raw diets to feed their animals but commercial raw food diets are also available.Frozen, or fresh-prepared, meals come in raw or cooked form, some of which is made with ingredients that are inspected, approved, and certified by the USDA for human consumption, but formulated for pets. Part of this growing trend is the commercialization of home-made dog food for pet owners who want the same quality, but do not have the time or expertise to make it themselves. The advantage is forgoing the processing stage that traditional dog food undergoes. This causes less destruction of its nutritional integrity.
The practice of feeding raw diets has raised some concerns due to the risk of foodborne illnesses, zoonosis and nutritional imbalances. People who feed their dogs raw food do so for a multitude of reasons, including but not limited to: culture, beliefs surrounding health, nutrition and what is perceived to be more natural for their pets. Feeding raw food can be perceived as allowing the pet to stay in touch with their wild, carnivorous ancestry. The raw food movement has occurred in parallel to the change in human food trends for more natural and organic products.
Senior dog diet
Senior dogs require specialized diets that are catered towards the aging animal. There are various physiological changes which a dog goes through as it ages. Commercially available senior dog diets address these changes through various ingredients and nutrients.When looking for a senior dog food, one of the first things that should be taken into consideration is the energy content of the diet. The maintenance energy requirements decrease as a dog ages due to the loss in lean body mass that occurs. Therefore, senior dogs will require a diet with a lowered energy content compared to non senior diets. Although senior dogs require lower energy content diets, they will also require diets that are higher in protein and protein digestibility. This is due to the fact that dogs have a reduced ability to synthesize proteins as they age.
Joint and bone health is an important factor to be considered when purchasing a senior dog food. The addition of glucosamine and chondroitin sulfate has been shown to improve cartilage formation, the composition of synovial fluid, as well as improve signs of osteoarthritis. The calcium to phosphorus ratio of senior dog foods is also important. Calcium and phosphorus are considered essential nutrients, according to AAFCO.
Gastrointestinal health is another important factor to consider in the aging dog. Sources of fiber such as beet pulp and flaxseed should be included within senior dog foods to help improve stool quality and prevent constipation. A current technology that is being used to improve gastrointestinal health of aging dogs is the addition of fructooligosacchardies and mannanoligosaccharides. These oligosaccharides are used in combination to improve the beneficial gut bacteria while eliminating the harmful gut bacteria.
The aging dog goes through changes in brain and cognitive health. There are two highly important ingredients that can be included in senior dog foods to help prevent cognitive decline and improve brain health. These ingredients are vitamin E and L-carnitne. Vitamin E acts as an antioxidant, which can prevent oxidative damage that occurs during aging. L-carnitine is used to improve mitochondria
Skin and coat health is important in all dogs, but especially becomes important as dogs age. An important nutrient to look for in senior dog foods to support coat health is linoleic acid, which can be found in corn and soybean oil. Another important nutrient is vitamin A, which helps with keratinization of hair. Good sources of vitamin A for skin and coat health include egg yolk and liver.
Immune system health has been shown to decline in aging dogs. The ratio of omega-6 to omega-3 fatty acids plays an important role in providing optimal health. Vitamin E can be used as an antioxidant in senior dog foods. Pre- and probiotics can also be added to senior dog foods to help improve the beneficial bacteria in the gut, providing support for the immune system.
Low-protein dog diet
According to The Association of American Feed Control Officials nutrient guideline for cats and dogs, the minimum protein requirement for dogs during adult maintenance is 18% on a dry matter basis. Other parts of the world would have a guideline similar to AAFCO. The European Pet Food Federation also stated a minimum of 18%. AAFCO only provided a minimum, but majority of the diets found on the market contain a protein level exceeding the minimum. Some diets have a protein level lower than others. These low-protein diets would not be seen with growth and reproductive life stages because of their higher demand for protein, as such, these diets are for dogs meeting maintenance levels. They can be purchased, such as vegetarian, vegan, weight control, and senior diets. Furthermore, this protein requirement varies from species to species.Disadvantages
There is an increasing risk of the practice of coprophagy when providing low-protein diets to dogs; a negative correlation exists between the amount of protein fed and the occurrence of coprophagy. Maintenance needs should still be met by low-protein diets, and the muscle turnover will also remain at an optimal rate, as long as the amino acid intake remains balanced and there are no limiting amino acids. However, there is a greater opportunity for amino acids to be balanced in diets containing higher protein content.Advantages
The dog's simple gastrointestinal tract contains a vast array of microbial populations; some members of this very diversified community include fusobacteria, proteobacteria, and actinobacteria. The gut microbiota of the dog will be comparable to that of the owners due to similar environmental impacts. Not only are the microbes influenced by the dog's environment, but they are also affected by the macronutrient content of the dog's diet. The populations present and health status of the microbiota found within the gut can alter the physiological and metabolic functions of the dog, which then subsequently affects susceptibility to disease development.Fermentation and digestion in the hindgut of a dog can potentially be improved depending on the source and the concentration of protein provide in a diet. Greater digestibility due to higher quality ingredients, in addition to lower protein concentrations within a diet, will help promote beneficial outcomes in assisting the health of a dog's gastrointestinal tract. Higher protein entering the gut will lead to more putrefaction that give rise to various toxins including carcinogens and increase the chances of many bowel diseases, such as colorectal cancer.
The age of dogs and cats is inversely proportional to protein consumption. As they age, the protein requirement decreases due to lower level of pepsin in their stomachs. There has also been discussion about higher protein content in diets being inversely related with lifespan, where lower protein content diets were related to longer lifespans.
Hypoallergenic diet
Dogs are prone to have adverse allergic reactions to food similar to human beings. The most common symptoms of food allergies in dogs include rashes, swelling, itchy or tender skin, and gastrointestinal upsets such as uncontrollable bowel movements and soft stools. Certain ingredients in dog food can elicit these allergic reactions. Specifically, the reactions are understood to be initiated by the protein ingredients in dog food, with sources such as beef, chicken, soy, and turkey being common causes of these allergic reactions. A number of "novel protein" dog foods are available that claim to alleviate such allergies in dogs.Hypoallergenic diets for dogs with food allergies consist of either limited ingredients, novel proteins, or hydrolyzed proteins. Limited ingredients make it possible to identify the suspected allergens causing these allergic reactions, as well as making it easy to avoid multiple ingredients if a canine is allergic to more than one. In novel protein recipes, manufacturers use ingredients which are less likely to cause allergic reactions in dogs such as lamb, fish, and rice. Hydrolyzed proteins do not come from a novel source; they could originate from chicken or soy for example. Hydrolyzed proteins become novel when they are broken apart into unrecognizable versions of themselves, making them novel to allergic gastrointestinal tracts.
Grain-free and low-carbohydrate diet
Some dog food products differentiate themselves as grain- or carbohydrate-free to offer the consumer an alternative, claiming carbohydrates in pet foods to be fillers with little or no nutritional value. However, a study published in Nature suggests that domestic dogs' ability to easily metabolize carbohydrates may be a key difference between wolves and dogs.Despite consumer and manufacturer claims that dogs perform better on grain-free diets, many veterinarians doubt their benefits, pointing to a historical lack of research documenting any benefits. In 2019, a study comparing dry dog food that was manufactured in the United States found that 75% of food containing feed grade grains also contained measurable levels of various mycotoxins, while none of the grain-free dry diets tested had any detectable levels of mycotoxins. Feed grade grains that are allowed to spoil and become moldy are the suspected source of the mycotoxins. This is the first published study to show a potential health benefit to feeding grain-free commercial dry pet foods.
In 2019, the U.S. Food and Drug Administration identified 16 dog food brands linked to canine heart disease. The FDA has investigated more than 500 cases of dilated cardiomyopathy in dogs eating food marketed as grain-free. The 16 brands are: Acana, Zignature, Taste of the Wild, 4Health, Earthborn Holistic, Blue Buffalo, Nature's Domain, Fromm, Merrick, California Natural, Natural Balance, Orijen, Nature's Variety, NutriSource, Nutro, and Rachael Ray Nutrish. These brands are labeled as “grain-free” and list peas, lentils, or potatoes as the main ingredient. The top three brands associated with reports of cardiomyopathy are Acana with 67 reports, Zignature with 64, and Taste of the Wild with 53 reports.
Vegetarian and vegan dog diet
Like the human practice of veganism, vegan dog foods are those formulated with the exclusion of ingredients that contain or were processed with any part of an animal, or any animal byproduct. Vegan dog food may incorporate the use of fruits like bananas, vegetables, cereals, legumes, nuts, vegetable oils, or soya, as well as any other non-animal based foods. The omnivorous domestic canine has evolved to metabolize carbohydrates and thrive on a diet lower in protein, and therefore, a vegan diet may be substantial if properly formulated and balanced.Popularity of this diet has grown with a corresponding increase in people practicing vegetarianism, and there are now various commercial vegetarian and vegan diets available on the market. Vegetarian dog foods are produced to either assuage a pet owner's ethical concerns or for animals with extreme allergies.
Due to the exclusion of animal products and by-products, which are primary ingredients of conventional dog food, many nutrients that would otherwise be provided by animal products need to be provided by replacement, plant-based ingredients. While both animal and plant products offer a wide range of macro and micronutrients, strategic formulation of plant ingredients should be considered to meet nutritional requirements, as different nutrients are more abundant in different plant sources. Despite the large differences in ingredient sourcing, studies have demonstrated that a plant-based diet can be just as edible and palatable as animal-based diets for dogs.
Some nutrients that require special consideration include protein, calcium, vitamin D, vitamin B12, taurine, L-carnitine, and omega-3 fatty acids, particularly DHA and EPA. Although their sources are more limited without animal products, it is possible to formulate a diet adequate in these nutrients through plant and synthetic sources.
Potential risks in feeding a plant-based diet include alkaline urine and nutrient inadequacy, especially in homemade diets. Adherence to recommendations by reliable sources is strongly advised.
Foods dangerous to dogs
A number of common human foods and household ingestibles are toxic to dogs, including chocolate solids, onion and garlic, grapes and raisins, milk, nutmeg, mushrooms, fatty foods, rhubarb, xylitol, macadamia nuts, as well as various plants and other potentially ingested materials.A full list of poison/toxic substances can be found on the ASPCA's website.
Recalls
The 2007 pet food recalls involved the massive recall of many brands of cat and dog foods beginning in March 2007. The recalls came in response to reports of renal failure in pets consuming mostly wet pet foods made with wheat gluten from a single Chinese company, beginning in February 2007. After more than three weeks of complaints from consumers, the recall began voluntarily with the Canadian company Menu Foods on March 16, 2007, when a company test showed sickness and death in some of the test animals.Overall, several major companies recalled more than 100 brands of pet foods, with most of the recalled product coming from Menu Foods. The contaminant was identified as melamine, which had been added as an adulterant to simulate a higher protein content.
In the United States, there has been extensive media coverage of the recall. There have been calls for government regulation of pet foods, which had previously been self-regulated by pet food manufacturers. The economic impact on the pet food market has been extensive, with Menu Foods losing roughly $30 million alone from the recall.
Contaminants
Mycotoxins
In April 2014, aflatoxin B1, a known carcinogenic toxin, melamine, and cyanuric acid were all found in various brands of USA pet food imported into Hong Kong. Since 1993, the FDA has confirmed concerns of toxins in feed grade ingredients, yet to date no comprehensive federal regulation exists on mycotoxin testing in feed grade ingredients used to make pet food.In 1997, the Journal of Food Additives and Contaminants established that low levels of various mycotoxins could cause health concerns in pets, and was found in feed grade ingredients.
A study published in the Journal of Food Protection in 2001 cited concerns regarding fungi in commercial pet foods and warned about the "risk for animal health".
In 2006, a study published in the Journal of Agricultural and Food Chemistry confirmed mycotoxins in pet foods around the world and concluded that contamination of mycotoxins in pet foods can lead to chronic effects on the health of pets.
In 2007, the International Journal of Food Microbiology published a study that claimed "mycotoxin contamination in pet food poses a serious health threat to pets", and listed them: aflatoxins, ochratoxins, trichothecenes, zearalenone, fumonisins and fusaric acid.
A 2008 study published in the Journal of Animal Physiology and Animal Nutrition found high levels of mycotoxins in the raw ingredients used for pet food in Brazil.
A 2010 study in the Journal of Mycotoxin Research tested 26 commercial dog foods and found mycotoxins at concerning sub-lethal levels. It was determined that long-term exposure to low levels of confirmed mycotoxins could pose chronic health risks.
For all the above reasons, a trend away from feed ingredients and toward USDA-certified ingredients fit for human consumption has developed.
In 1999, another fungal toxin triggered the recall of dry dog food made by Doane Pet Care at one of its plants, including Ol' Roy, Wal-Mart's brand, as well as 53 other brands. This time the toxin killed 25 dogs.
A 2005 consumer alert was released for contaminated Diamond Pet Foods for dogs and cats. Over 100 canine deaths and at least one feline fatality have been linked to Diamond Pet Foods contaminated by potentially deadly aflatoxin, according to Cornell University veterinarians.
''Salmonella'' and other concerns
The FDA released a video focusing on another major threat in commercial pet food: Salmonella bacterial contamination. They also cite other major toxins of concern. The video references the case of a specific commercial pet food plant that was also the subject of a March 2014 study published in the Journal of the American Veterinary Medical Association. It details how at least 53 known human illnesses were linked to commercial pet foods made at that plant in 2012. A class action lawsuit linked to this outbreak was settled in 2014.The video also cites the dangers of over supplementation of nutrients in pet food. A study published in the Journal of the American Veterinary Medical Association in February 2013 suggested a correlation between liver disease and the amount of copper supplementation in AAFCO diets.