Dog food is food specifically intended for consumption by dogs. Like all carnivores, dogs have sharp, pointed teeth, and have short gastrointestinal tracts better suited for the consumption of meat. In spite of this natural carnivorous design, dogs have still 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.
In the United States alone, dog owners spent over $8.6 billion on commercially manufactured dog food in 2007. Some people make their own dog food, feed their dogs meals made from ingredients purchased in grocery or health food stores or give their dogs a raw food diet.
History
In 37 BCE Virgil talks about the feeding of dogs in his Bucolics:
Nec tibi cura canum fuerit postrema; sed una Veloces Spartae catulos, acremque Molossum, Pasce sero pingui:
"Do not let the care of dogs be last; but the swift Spartan hounds, and fierce Mastiff, Feed the whey"
Around 70 CE, Columella wrote his book On Agriculture in which he addresses the feeding of dogs:
Cibaria fere eadem sunt utrique generi praebenda. Nam si tam laxa rura sunt, ut sustineant pecorum greges, omnis sine discrimine hordeacea farina cum sero commode pascit. Sin autem surculo consitus ager sine pascuo est, farreo vel triticeo pane satiandi sunt, admixto tamen liquore coctae fabae, sed tepido, nam fervens rabiem creat.
"Provisions of victuals are almost the same for both [types of dog]. If the fields are so large as to sustain herds of animals, barley meal mixed with whey is a convenient food. But if it is an orchard without grain, spelt or wheat bread is fed mixed with the liquid from cooked beans, but warm, for boiling creates rabies."
In the Avesta, written from 224 to 651 CE, Azura Mazda advises:
Bring ye unto him milk and fat with meat; this is the right food for the dog.
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 (the dregs of the tallow pot) to dogs, though the English favored them (see below), and suggested a meat-flavored soup:
By a misguided economy dogs are given meat scraps and tallow graves; one must avoid this, because these foods make them heavy and sick; give them twice a day a soup of coarse bread made with water, fat and the bottom of the stew pot; put a half-kilogram of bread at least in each soup.
In England, care to give dogs particular food dates at least from the late eighteenth century, when The Sportsman's dictionary (1785) described the best diet for a dog's health in its article "Dog":
A dog is of a very hot nature: he should therefore never be without clean water by him, that he may drink when he is thirsty. In regard to their food, carrion is by no means proper for them. It must hurt their sense of smelling, on which the excellence of these dogs greatly depends.
Barley meal, the dross of wheatflour, or both mixed together, with broth or skim'd milk, is very proper food. For change, a small quantity of greaves from which the tallow is pressed by the chandlers, mixed with their flour ; or sheep's feet well baked or boiled, are a very good diet, and when you indulge them with flesh it should always be boiled. In the season of hunting your dogs, it is proper to feed them in the evening before, and give them nothing in the morning you take them out, except a little milk. If you stop for your own refreshment in the day, you should also refresh your dogs with a little milk and bread.
(Greaves, which was often recommended for dogs, is "the sediment of melted tallow. It is made into cakes for dogs' food. In Scotland and parts of the US it is called 'cracklings'.")
In 1833, The Complete Farrier gave similar but far more extensive advice on feeding dogs:
The dog is neither wholly carnivorous nor wholly herbivorous, but of a mixed kind, and can receive nourishment from either flesh or vegetables. A mixture of both is therefore his proper food, but of the former he requires a greater portion, and this portion should be always determined by his bodily exertions.
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:
The first three prize winners at the late coursing meeting at Great Bend were trained on Spratt's Patent Dog Biscuit. This same dog food won no less than three awards, including a gold medal, at the Exposition in Paris which has just closed. It would seem that the decision of the judges is more than backed up by the result in the kennel. Another good dog food is that manufactured by Austin & Graves, of Boston. They, too, seem to be meeting with great success in their line.
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 deceased horses. 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.
Foods dangerous to dogs
A number of common human foods and household ingestibles are toxic to dogs, including chocolate solids (theobromine poisoning), onion and garlic (thiosulfate, sulfoxide or disulfide poisoning), grapes and raisins (cause kidney failure in dogs), milk (some dogs are lactose intolerant and suffer diarrhea; goats' milk can be beneficial), nutmeg (neurotoxic to dogs), 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.
Food allergies in dogs
Certain ingredients in dog food are known to be a key cause of allergies. A popular belief among pet owners is that wheat and soybeans are a leading cause of dog allergies, however many studies backed by veterinarians have failed to show wheat and soybeans as major causes of allergic reactions, and in fact blame the meat protein such as beef, chicken and lamb for most allergies. A number of "grain free" dog foods are available that claim to alleviate such allergies in dogs. Given the current research, wheat/grain allergies are rare in dogs. However, gluten intolerance is more prevalent in certain breeds such as the Irish Setter.
Diets for those dogs allergic to food are made from limited ingredients or hypoallergenic recipes. Limited ingredients make it easier to identify the suspected allergens. In hypoallergenic recipes, manufacturers use those ingredients which are less likely to cause allergies to the dogs such as lamb, fish, and corn. Food allergies account for about 10% of all the allergies seen in dogs, being the most common cause after flea bite allergies and atopy (inhalant allergies). Food allergies generally account for 20% of the causes of itching and scratching in dogs.
Grain free/low carbohydrate
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. Carbohydrates in dog food contribute to approximately 3.5 cals of energy per gram, the same as protein per the modified Atwater method of calculating metabolizable energy. The grain-free diets have created a trend toward avoiding commercial pet food. However, a recent study published in Nature suggests that domestic dogs are able to metabolize carbohydrates.
Contamination issues
Melamine
In 2007, following a series of reports of renal failure in pets, there was a widespread recall of pet foods due to contamination found in ingredients produced in China. The contaminant was identified as melamine which had been added as an adulterant to simulate a higher protein content.
Salmonella and other concerns
Recently, the FDA has 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 recently settled.
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.
In addition "taurine deficiency" has been found in dogs and cats fed commercial diets intended to be "complete and balanced". Not usually considered an essential nutrient in dogs, taurine is plentiful in most whole meats whether raw or cooked, but is reduced in extruded diets. Cats require more taurine in their diets due to their increased rate of protein metabolism; taurine is usually synthesized in the body from methionine and cysteine, but cats' increased use of these amino acids in normal bodily functions mean that taurine itself must also be provided in the diet.
The above observations could also be explained by the rendered, highly processed source of meat being less rich in taurine and by the fact that some of the taurine is denatured during extrusion. Cats are obligate carnivores and their natural diet would consist of high amounts of whole meat - thus what has been termed "taurine deficiency" causing dilated cardiomyopathy in cats, is more likely to be a deficiency in the production of commercial feed diets. Taurine is now artificially supplemented back into the diet after processing in the production of most commercial pet food. A similar dynamic occurred in the first half of the twentieth century with an epidemic of Pellagra in humans living in the Southern United States. The cause was determined to be a deficiency of the essential vitamin niacin (B3), which was being destroyed in the mass processing of corn. Niacin was supplemented back into Southern diets and the disease was eradicated.
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 (animal grade) ingredients, yet to date no comprehensive federal regulation exists on mycotoxin testing in feed grade (animal 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 (the source of mycotoxins) 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.
A 2012 study published in the journal of Toxins found concerning levels of multiple mycotoxins in pet food in Europe, which has some of the strictest guidelines.
For all the above reasons, a current trend away from feed ingredients, and toward USDA certified ingredients fit for human consumption has developed.
Commercial dog food
Most store-bought dog food is made with feed grade (animal grade) ingredients and comes in either a dry form (also known in the US as kibble) or a wet, canned form. Dry food contains 6â€"10% moisture by volume, as compared to 60â€"90% in canned food. Semi-moist foods have a moisture content of 25â€"35%. Pet owners often prefer dry food for reasons of convenience and price, spending over $8 billion on dry dog food in 2010 â€" a 50% increase in the amount spent just seven years earlier.
Dry dog food
Dry food processing done is popular in the pet food industry as it is an efficient way to supply continuous production of feed in various variety as 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.
Structure of Extruder
A simple extruder consists of a barrel, helical screws, and a die (tool to cut and shape food). Some extruders in the United States also contain a fat distributor, and the food mixture enters the barrel of the extruder through a funnel-like structure. Fat is stored in a container where is it pumped through a heat exchanger and fed through a line connected to the barrel of the extruder with a valve to prevent backflow of fat. A metering device connected to this line allows for control of fat amounts deposited in the mixture. Pressure is applied by helical screws that is driven by a motor. Food mixture is shaped through a die when extrusion process concludes; allowing fly knife to cut extruded feed.
Extrusion Process
Mixture of feed ingredients are solid at room temperature therefore; the extrusion process of these ingredients requires a temperature higher than this in order to soften or melt the mixture and allow for fluidity through the barrel. In the United States, before entering the extruder, water is added to the starch mixture to elevate the moisture content to 20 to 35%. 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. The material is put through high amounts of shear stress that generates heat which allows for mixture to come together. Temperature in the extruder is raised to above 100 degrees Celsius by the use of steam, hot water, or other heat sources. The pressure is increased to allow starch granules to gelatinize. Fat used in US extruders is then added into the mixture at the metering zone of the extruder which allows for the incorporation of fat, but without affecting the product's ability to expand. Feed mixture stays in the extruder for only 15 to 120 seconds before exiting through die openings. As the feed exits the extruder, it is subjected to relatively lower amounts of heat and pressure, that results in the expansion of the product, creating its “puffed†kibble appearance. The feed is expelled in one long sequence where it is cut to its desired size by a rotating fly knife. As moisture of this extrudate is at roughly 20 to 35% of its weight, it is dried further in an oven to reduce its moisture content to 8 to 10%.
Wet dog food
Wet or canned dog food is significantly higher in moisture than dry or semi-moist food. Canned food is commercially sterile (cooked during canning); other wet foods may not be sterile. Sterilizing is done through the process of retorting. A given wet food will often be higher in protein or fat compared to a similar kibble on a dry matter basis (a measure which ignores moisture); given the canned food's high moisture content, however, a larger amount of canned food must be fed. Grain gluten and other protein gels may be used in wet dog food to create artificial meaty chunks, which look like real meat.
Canning 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 down 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.
Retort Process
For canned pet foods in the United States, a process known as retort is employed to sterilize the product using steam. It is important to ensure that the formulation made is resistant to bacterial contamination and spoilage. The now canned mixture is placed in a retort where steam brings the temperature up to 121 degrees Celsius. To ensure that heat reaches the center of the mixture, the can stays inside the retort for roughly 75 minutes. However, some steam retorts are able to reach the center of the can in only 10 minutes.Â
Alternative dog food
In recent years, alternatives to traditional commercial pet food are being sold. Many companies have been successful in targeting niche markets, each with unique characteristics. Some popular alternative dog food labels are:
- Frozen, also called fresh-prepared, comes in raw or cooked (not processed) 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 idea is to skip the processing stage traditional dog food goes through. This causes less destruction of its nutritional integrity.
- Dehydrated or freeze-dried comes in raw and cooked form. Products are usually air dried or frozen, then dehydrated (freeze-dried) 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.
- Fresh or refrigerated, produced through pasteurization of fresh ingredients. Products are lightly cooked and then quickly sealed in a vacuum package. Then they are refrigerated until served. This type of dog food is extremely vulnerable to spoiling if not kept at a cool temperature and has a shelf life of 2â€"4 months, unopened.
- Homemade diet often comes in a bucket or Tupperware-like package. In the past this was thought to be a diet that owners create themselves. These diets generally consist of some form of cooked meat or raw 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. Recently, small companies have begun to home-cook dog dishes and then sell them through specialty stores or over the Internet.
- Vegetarian dog foods are manufactured by several companies. They are usually balanced and contain ingredients such as oatmeal, pea protein, and potatoes instead of meat to supply protein. A dog owner may choose to feed a vegetarian food for ethical and/or health reasons, or in cases of extreme food allergies.
Contents
Many commercial dog foods are made from materials considered by some authorities and dog owners to be unusable or undesirable. These may include:
- Meat and bone meal
- Offal (wild canines, however, do eat offal as a vital part of their diets)
- Animal digest
- Sucrose and/or fructose
- Animal by-products
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. Ingredients must be listed by amount in descending order.
According to the Association of American Feed Control Officials (AAFCO), animal by-products in pet food may include parts obtained from any animals which have died from sickness or disease provided they are rendered in accordance to law. As well, 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 â€" those who enter the food chain as dead, dying, diseased or disabled.
One emerging differentiation between pet food qualities in the United States is the use of standard feed grade (animal grade) ingredients versus the use of USDA-inspected, approved, and certified ingredients fit for human consumption. The USDA certification and approval process is among the best quality control programs in food production in the world. The US Food and Drug Administration (FDA) has recently commented that the ingredients defined as feed in pet food (feed grade or animal grade) are not classified as generally recognized as safe (GRAS). Examples of potential toxins include melamine, Salmonella, and mycotoxins. Only the language "USDA certified" or "USDA approved" is legally meaningful. Some companies will say "Made with ingredients from a USDA facility", or "USA Meat", which is misleading as it can include dead or dying animals or carcasses rejected from the human food chain and is not the same as USDA inspected, approved, or certified, which are FDA approved for human consumption.
Packaging
Dry dog food (kibbles) is most often packed in multi-wall paper bags, sometimes with a plastic film layer; similar bag styles with film laminates or coextrusions are also used. Wet dog food is often packed in aluminum cans or steel cans. Packaging regulations for dog food are often very similar to corresponding regulations for human foods.
Raw dog food
Supporters of raw feeding believe that the natural diet of an animal in the wild is its most ideal diet and try to mimic a similar diet for their domestic companion. They are commonly opposed to commercial pet foods, which they consider poor substitutes for raw feed. Opponents believe that the risk of food-borne illnesses posed by the handling and feeding of raw meats would outweigh the purported benefits and that no scientific studies have been done to support the numerous beneficial claims. The Food and Drug Administration of the United States states that they do not advocate a raw diet but recommends owners who insist on feeding raw to follow basic hygienic guidelines for handling raw meat to minimize risk to animal and human health.
Many commercial raw pet food manufacturers now utilize a process called High Pressure Pascalization (HPP) that is a unique process that kills pathogenic bacteria through high-pressure, water-based technology. High Pressure Pascalization is a USDA-approved, and is allowed for use on organic and natural products.
Commercial frozen raw dog food is distributed by various independent pet specialty retailers.
Senior dog food
Senior dogs require specialized diets that are catered towards the aging animal. There are various physiological changes in 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 noted 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 does 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 have 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 fibre 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 good gut bacteria while eliminating the bad gut bacteria.
Labeling
In the United States, dog foods labelled as "complete and balanced" must meet standards established by the Association of American Feed Control Officials (AAFCO) either by meeting a nutrient profile or by passing a feeding trial. The Dog Food Nutrient Profiles were last updated in 1995 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. 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.
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 have recalled more than 100 brands of pet foods, with most of the recalled product coming from Menu Foods. Although there are several theories of the source of the agent causing sickness in affected animals, with extensive government and private testing and forensic research, to date, no definitive cause has been isolated. As of April 10, the most likely cause, according to the FDA, though not yet proven, is indicated by the presence of melamine in wheat gluten in the affected foods.
In the United States, there has been extensive media coverage of the recall. There has been widespread public outrage and 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. The events have caused distrust of most processed pet foods in some consumers.
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 the potentially deadly toxin, Aflatoxin, according to Cornell University veterinarians.
In recent years, recalls of traditional and raw commercial pet foods have become frequent due to increased awareness and testing by the FDA. Every few months a new large scale recall is announced and a dynamic list of recall alerts is being continually updated by the FDA
See also
- Dog food brands
- Dog biscuits
- Dog meat
- Puppy nutrition
- Dental health diets for dogs
- Cat Food
- Senior dog diet
- Dog odor
References
External links
- Interpreting pet food labels â€" Pet food labeling according to AAFCO regulations
- National Research Council (U.S.). Subcommittee on Dog Nutrition (1974). Nutrient requirements of dogs. National Academy of Sciences. ISBNÂ 0-309-02315-7.Â