Raw Meat-Based Dog Food Diets
Critics of raw meat-based diets point to the dangers of contamination by bacteria, parasites, and protozoa. How real are these threats?
There are some very high-profile illnesses that can result from handling raw meat – scarifying things like E. coli, salmonella, and trichinella. The mere idea of these threats prevents many people interested in “raw feeding” from giving this type of highly beneficial diet a try. So, we’re going to demystify everything that could go wrong with raw meat (but probably won’t). We’ll describe some horrible diseases, and how they would affect a person who got them, and how they would affect a dog.
But don’t be put off; these things just don’t seem to happen to the kind of educated, conscientious dog owners who are reading this article and trying to provide their dogs with the healthiest diets possible.
In fact, we made inquiries with several veterinary nutrition experts, and none of them had ever personally seen a dog who had become infected with one of these pathogens by eating human-grade raw meat. They’ve seen problems with ALL-meat diets – of course! Dogs are omnivores, and require more than meat alone!
They’ve seen problems with feeding dogs so-called 4-D meat, that is, “condemned meat” that came from animals that were dead, down, dying, or diseased animals that could not pass for human-grade food. Of course problems would result from feeding this sort of unhealthy meat!
And they’ve seen problems with dietary imbalances; most of us still have a lot to learn about designing a nutritionally complete homemade diet. (In fact, we’re going to talk about formulating homemade diets in an upcoming issue this fall.)
But none of the experts we spoke with could cite a case where a dog contracted one of the illnesses we discuss below from eating human-grade raw meat.
Terms of engagement
There are several ways that illness-inducing organisms in raw meat can pose a danger to you and/or your dog:
1. Your dog eats harmful pathogens present in raw meat that is infected and becomes ill.
2. In the process of preparing your dog’s raw meat, pathogens that are present in or on the meat infects your food preparation tools or area, and, in turn, infects your food and causes illness in your human family.
3. Your dog eats harmful pathogens present in raw infected meat and becomes ill. You come into contact with a later stage of the pathogen, in the form of organisms shed in the sick dog’s diarrhea.
According to experienced “raw feeders,” fastidious meat selection, preparation, and storage techniques can prevent most of the illnesses we’re about to discuss in detail. However, people who are still nervous about these risks can employ various levels of precautions to protect themselves, their dogs, and their families while optimizing the dog’s diet through at-home preparation of the dog’s food.
To begin with, if feeding raw meat is just too terrifying for people to contemplate, they can cook the meat! Thorough cooking kills all of the potentially infective agents mentioned below – and we would rather see people feeding their dogs a diet that includes cooked meat than one that includes kibble!
Virtually all of the people who have warned us over the years about the potential dangers of feeding raw meats either work for or have done research for dog food companies; these are people with a vested interest in warning people away from feeding real food to their dogs. It’s hard to trust people who have something to sell, and dog food is a multi-billion-dollar industry these days.
We’d rather trust the hundreds of people who have written to us to describe how much healthier, stronger, and energetic their dogs are, and the holistic vets who have told us how their clients’ dogs are less prone to illness, injury, or disease since they began feeding raw meat. We’ll believe the people who have actually tried feeding a meat-based diets, and found that it really works for dogs.
This infectious disease is the most common cause of diarrheal illness in the U.S. It is caused by contact with Campylobacter bacteria, generally through the handling or consumption of raw or undercooked infected poultry. More than 10,000 human cases are reported to the Centers for Disease Control (CDC) annually, but many more cases go undiagnosed or unreported; the CDC estimates two million people each year are infected.
People who become ill with Campylobacteriosis get diarrhea, cramping, abdominal pain, and fever within two to five days of exposure to the organism, although some people who become infected do not experience symptoms. The diarrhea may be bloody, and can be accompanied by nausea and vomiting. The illness typically lasts one week. In people with compromised immune systems, Campylobacter can spread to the bloodstream and cause a serious, life-threatening infection.
Campylobacter lives in the intestines of infected chickens, contaminating the chicken meat during slaughter. According to the CDC, more than half of the raw chicken in the U.S. market has Campylobacter on it. The best way for people to avoid infection with this bacteria is to practice stringent safe handling of raw poultry.
Dogs may be infected with Campylobacter and suffer no symptoms; dogs and cats appear to be better adapted to the bacteria than humans. When clinical illness develops in a dog, it is generally in puppies less than six months of age and/or under unusual stress. Treatment with oral antibiotics often takes care of the illness, but many strains are proving to be resistant to antibiotics, due to the aggressive use of antibiotics in animal feeds.
There are actually four recognized classes and hundreds of strains of E. coli, and the effect and relative dangers of each is different. But whether exposure to E. coli causes diarrhea in dogs is as yet unresolved. The danger of E. coli-infected meat would appear to threaten only the humans in the household, and only through shoddy meat handling practices.
The organism lives in the intestines of healthy cattle. Meat can become contaminated during slaughter, and organisms can be thoroughly mixed into beef when it is ground. Bacteria present on the cow’s udders or on equipment may get into raw milk. Contaminated meat and milk looks and smells normal.
E. coli also naturally resides in the intestines of healthy humans, so person-to-person contact in families and child care centers is often seen as a mode of transmission. Infection can also occur after drinking raw infected milk and after swimming in or drinking sewage-contaminated water.
Some strains of E. coli are harmless; mild forms of E. coli cause what is commonly referred to as “travelers’ diarrhea.” The most potent form (known as E. coli O157:H7) can cause intensely painful, bloody diarrhea. In some people, particularly children under five years of age and the elderly, the infection can cause a complication called hemolytic uremic syndrome, in which the red blood cells are destroyed and the kidneys fail. About two to seven percent of infections lead to this complication, which usually must be treated in an intensive care unit and may require blood transfusions and kidney dialysis. Most people, however, recover without antibiotics or other treatment in 5-10 days. An estimated 73,000 cases of infection and 61 deaths occur in the U.S. annually.
The is a serious infection caused by eating food that has been contaminated by Listeria monocytogenes. The symptoms include fever, muscle aches, and sometimes gastrointestinal symptoms such as diarrhea or nausea. If infection spreads to the nervous system, headache, stiff neck, confusion, loss of balance, or convulsions may occur. Infected pregnant women may experience only a mild flu-like illness, but this can lead to premature delivery, infection of the newborn, or even stillbirth.
As estimated 2,500 people become seriously ill with Listeriosis each year, and about 500 of these die. At increased risk are pregnant women (who make up about one-third of the affected people); newborns; people with weakened immune systems or AIDS (AIDS patients are 300 times more likely to get Listeriosis than people with normal immune function); people with cancer, diabetes, or kidney disease; and the elderly. Healthy adults and children occasionally get infected with Listeria, but they rarely become seriously ill. The infection may be identified only with a culture of the patient’s blood or spinal fluid.
Raw meat can be infected with Listeria monocytogenes, but because the bacteria is naturally found in soil and water, vegetables and dairy products are also included on the list of suspects when Listeriosis strikes.
We could find no record of dogs becoming infected with Listeria from eating infected meat. There have been cases of dogs with Listeriosis, but the route of infection was thought to be oral contact with infected dirt or silage.
The disease in dogs is sometimes referred to as “circling disease,” as an infected dog often displays neurologic signs such as ataxia (loss of balance), circling, or head tilting. Treated early with vigorous antibiotic therapy, the prognosis is good.
The Salmonella bacteria lives in the gastrointestinal tract of infected humans and animals, and is present in their feces; people and dogs can be infected with the bacteria without any signs of illness.
People who do become ill generally develop diarrhea, fever, and abdominal cramps 12 to 72 hours after infection. The illness usually lasts 4 to 7 days, and most people recover without treatment, although the elderly, infants, and those with impaired immune systems may experience severe illness. In some cases the diarrhea may become so severe that the person needs to be hospitalized. In these patients, the Salmonella infection can sometimes spread from the intestines to the blood stream, and can even cause death unless promptly treated with antibiotics. Unfortunately, some Salmonella bacteria have become very resistant to antibiotics, largely due to the use of antibiotics to promote the growth of food animals.
About 40,000 cases of Salmonellosis are reported each year in the U.S. The CDC estimates that the actual number of cases is perhaps 20 times greater than this, since most cases are not diagnosed or reported. An estimated 1,000 people die annually due to Salmonella infections.
Pet reptiles, especially turtles, are particularly likely to harbor Salmonella; people should always wash their hands after handling reptiles. But Salmonella is often transmitted to people by eating foods that have been contaminated with feces from an infected animal. It should be noted that such foods usually look and smell normal. Beef, poultry, milk, or eggs are the most commonly infected foods, but even vegetables may be infected.
Dogs may harbor Salmonella bacteria for years without suffering gastrointestinal problems, until illness is triggered by unusual stress. The stress of hospitalization, anesthesia, immuno-suppressive therapy, concurrent disease, and overcrowding has been correlated with an increased risk of Salmonellosis in dogs.
Signs of infection in dogs are variable, and most occur within a few days of stress or hospitalization. Fever, malaise, and anorexia are noted initially, followed by vomiting, abdominal pain, and diarrhea. Because Salmonella gastroenteritis is usually self-limited, and because antibiotic resistance is so common, antibiotics are generally not used to treat the infection. Supportive therapies for effects of diarrhea are helpful.
PARASITIC AND PROTOZOAN THREATS
A quote from the Food Safety and Inspection Service (FSIS), a branch of the U.S. Department of Agriculture, may be instructive here: “The presence of parasites in meat is repugnant to the consumer whether or not the parasites are transmissible to humans.” In other words, parasites are one thing that meat inspectors really look for when examining meat for human consumption.
There are two types of parasites of meat animals in this country that are directly transmissible to humans through the consumption of meat: Trichinella, most often observed in pork but sometimes found in beef, and tapeworms.
This disease is caused by eating raw or undercooked meat infected with the larvae of a species of worm called Trichinella. The parasite can infect beef, but is almost always seen in pork.
According to the USDA, Trichinella is unique among the parasites encountered in meat inspection in that it cannot be diagnosed by examination of the carcass and, as yet, there is no test that will guarantee freedom from the presence of the parasite. Therefore, they advise the consumer to “assume that all swine are infested and must be sufficiently treated to destroy Trichinae by heating, freezing, curing, or use of irradiation. The consumer is expected to thoroughly cook those fresh pork cuts that have not been processed to destroy Trichinae.”
Trichinosis is very rare in dogs, but the disease in humans is so serious that the disease is always mentioned in discussions of feeding raw meat. For this reason, few raw feeders utilize pork in their dogs’ diets.
Infected meat actually contains worm larvae, which develop into worms in the new host. These worms travel through the arteries and are transported to muscle tissue, where they encyst. Nausea, diarrhea, vomiting, fatigue, fever, and abdominal discomfort are the first symptoms, occurring within a day or two of eating infected meat. Further symptoms – headaches, fevers, chills, cough, eye swelling, aching joints and muscle pain, itchy skin, diarrhea or constipation – usually start within two to eight weeks. The severity of the symptoms is directly related to the number of infectious larvae consumed. Often mild cases of trichinosis are never diagnosed or assumed to be the flu or some other illness. A blood test or muscle biopsy is needed to diagnose trichinosis.
Though this disease was once considered very common in the U.S., infection is considered by the CDC to be fairly rare today, with an average of 38 cases being reported each year. The decrease is attributed to legislation prohibiting the feeding of raw meat garbage to hogs, commercial and home freezing of pork, and public awareness of the danger of eating raw pork products. Freezing cuts of pork that are less than six inches thick for 20 or more days at 5 degrees F. will kill any worms present; however, similar treatment will not kill larvae present in wild game meat.
There are numerous types of tapeworms that can infect dogs and people, and some are transmitted through the ingestion of infected meat. Echinococcus granulosus and E. multiocularis, also known as “hyatids,” commonly infect lamb; Taenia saginata, also known as the common tapeworm, is usually found in cattle. A related tapeworm, Taenia solium, exists in the larval state in the muscles of the hog. The larvae exist in the muscles and organs of these food animals. If they detect tapeworms, meat inspectors condemn the carcass or compel the meat to be rendered safe through a special freezing or heating process; however, one must imagine that not every infection can be detected.
Cooking meat kills the larval form of all tapeworms; freezing the meat does, too. However, the temperatures required to kill any tapeworm larvae present are rarely approximated by home freezers. Most home appliances are set to a temperature just around freezing (32 degrees F.) The USDA uses temperatures of no more than 15 degrees Fahrenheit for 10 to 20 days to inactivate tapeworm larvae.
Infected dogs rarely show signs of disease unless the tapeworms are present in very high numbers from multiple exposures.
Meat is not the only vehicle for tapeworm transmission. The most common route of dog-to-human tapeworm infection is through accidental ingestion of infected flea larvae or lice, or through eating vegetation such as nuts, berries, or herbs that became contaminated through infected dog, cat, fox, or other canid feces.
There are numerous protozoans (single-celled creatures) that can infect dogs if they are present in meat and are consumed. Toxoplasma gondii, a protozoan that causes the disease known as toxoplasmosis, is the best known, but its habits and effects are not completely understood. The creature generally replicates in intestinal walls, although it can invade and colonize in the central nervous system. The disease in humans may resemble as little as a mild cold – or can lead to hepatitis, pneumonitis, myocarditis, or meningoencephalitis.
Carnivores and omnivores can become infected by eating raw infected meat, but infection can also be congenital (present from birth due to transmission in utero from an infected mother), or a result from exposure to infected feces. Since many dogs eat feces occasionally (and a few eat feces whenever they can), this must be considered as a probable cause in many cases. According to some estimates, about 40 percent of all cats and humans in the U.S., and 20 percent of all dogs in the U.S., already have Toxoplasma gondii present in their bodies. The disease usually develops only in animals and humans with an immuno-deficiency.
Cooking meat inactivates any tissue cysts that are present. Freezing meat inactivates many – but not all – protozoal tissue cysts.
In recent years, another protozoan has been widely reported as causing disease in dogs. Infection with Neosporum caninum causes a disease called neosporosis, which is characterized by paralysis and atrophy of the hind limbs.
Early studies are showing Neosporum caninum to be ubiquitous in the worldwide cattle population, so concern has increased that dogs (and people) could become infected with the protozoan through the consumption on uncooked or undercooked meat. However, the only proven route of transmission in dogs is transplacental.
Are we vegetarians yet?
The more you learn about the potential dangers of food, the less you want to eat anything; meat is perhaps the worst example. But dogs need meat – preferably raw, but cooked meat is better than none.
Not every food animal that is infected with a potentially harmful pathogen can be detected and rejected from the human food supply, but considering the scale of the project, food inspectors do a heroic job. If you do your part – buying the best meats from reputable markets, handling and storing the meat assiduously, and feeding it to healthy dogs – the odds are, neither you nor your dogs will ever experience any of the problems described here.
-By Nancy Kerns