By Dr. Becker
Given the embarrassing number of processed pet food recalls in recent years due to salmonella contamination, coupled with the FDA's zero-tolerance policy for salmonella in pet food and treats,1 as you might guess, one of the primary concerns of pet food manufacturers is the potential for salmonella contamination of their products, especially kibble.
As an aside, many people don't realize that salmonella infections from pet food are much more likely to occur in the humans handling it than the animals eating it, unless the pet is immunosuppressed or there's an unusually high level of contamination.
Dry pet food is heat-treated twice, once during pre-conditioning and again during extrusion, and the raw materials (such as meat meals) have been heated and processed extensively before being added to the kibble "batter." The very high temperatures used in these processing steps should kill the salmonella present in the food, however, recontamination can and does occur after the food is extruded — possibly inside the conveying system or from airborne dust in air-handling systems.
There are a number of tactics pet food producers use to control salmonella contamination, including vendor inspections, hazard analysis and critical control point plans and hold-and-release programs. Potential additives, some of them quite bizarre, are also routinely investigated for their ability to control salmonella.
Study Investigates Bodybuilding Supplement for Use in Salmonella Control
One such substance I read about recently is 3-hydroxy-3-methylbutyric acid (HMB, not to be confused with 3-hydroxybutyric acid). HMB is a breakdown product of the amino acid leucine. Small amounts of HMB are present in certain foods, including alfalfa, asparagus, avocados, cauliflower, grapefruit, catfish and milk.2 HMB is also naturally synthesized in the human body. It's produced by the liver and muscles, and is thought to be involved in muscle protein synthesis.3
HMB is sold as a dietary supplement to (human) athletes and exercisers who want to add muscle mass and reduce recovery times. It's also found in certain medical foods designed to provide nutritional support to people with diseases that cause muscle wasting, as well as to promote wound healing after surgery or injury.
If you're wondering how a bodybuilding supplement has anything to do with controlling salmonella on dry pet food, welcome to the club. For reasons known only to them, recently a manufacturer of HMB supplements and scientists at Kansas State University conducted a study on the ability of the chemical to prevent recontamination by salmonella after the pet food extrusion process.4
Can Spraying HMB on Kibble Help Control Salmonella Contamination?
The researchers ran three trials using five different concentrations of two forms of HMB sprayed onto kibble post-extrusion. After spraying the HMB, they injected the dry food with a strain of salmonella bacteria. The control kibble sample did not get treated with HMB, but did get exposed to the salmonella.
At specific intervals over the next two weeks, the researchers measured the kibble for the presence of bacteria, and observed that the HMB reduced salmonella growth compared to the control sample. At the end of the two weeks, the HMB had eliminated detectable salmonella contamination on the treated samples. Study author John Fuller, Ph.D., told PetfoodIndustry.com:
"As with any scientific hypothesis, it generally takes repeated studies to have widely accepted support for the hypothesis. We are confident in the data we have generated as this was generated in two independent laboratory settings. Thus, this could provide the basis for commercial use; however, these results should be repeated in an actual commercial setting."5
HMB Provides yet Another Marketing Opportunity for Pet Food Companies
How fortunate is it for processed pet food manufacturers that a chemical that appears to kill salmonella in finished product kibble also just happens to be an athletic performance supplement? According to PetfoodIndustry.com:
"HMB can be found on the shelves of dietary supplement stores, where it is marketed as a means to build lean muscle and speed healing after hard weightlifting sessions. Also, physiologists and biologists have found empirical evidence to back up those marketing claims."
Study co-author Fuller, who works for an HMB supplement manufacturer, believes the chemical may provide similar benefits for working and athletic dogs.
"The intended use would be as an anti-microbial when added to or coated on the food," says Fuller, "but yes it could have a physiological effect as well similar to the effect seen in humans."
Studies of HMB in humans and horses show the substance does help with recovery from strenuous exercise, and helps athletes of both species "train and work harder." There are no published studies involving dogs, but Fuller's company has done some pilot studies that indicate "a distinct benefit for racing and working dogs."
Needless to say, when and if HMB is approved for use in pet food, its benefit as a salmonella killer won't be mentioned on product advertising, but you can bet its potential to improve the condition, performance and recovery of working and athletic dogs will be.
Lipstick on a Pig
The good news is pet food companies are actively searching for ways to reduce exposure to salmonella bacteria in their products. And as chemical pet food additives go, 3-hydroxy-3-methylbutyric acid appears to be relatively benign. The bad news? Adding a substance like HMB to dry pet food is a little like putting lipstick on a pig (no offense to pigs, since they're actually quite adorable). The pig may look more attractive, but it's still a pig.
Salmonella-free kibble is still kibble. Aside from poor-quality meats, byproducts and synthetic vitamins and minerals, most commercial dry pet foods are built around high glycemic, genetically engineered (GE) corn, wheat, rice or potato — grains and starches that have no place in your pet's diet and create metabolically stressful insulin, glucagon and cortisol spikes throughout the day.
In fact, many grain-free dry foods have a higher glycemic index than pet foods containing grain due to the excessive amounts of potatoes, peas, lentils or tapioca included in the formulas.
Carbs also break down into sugar, which fuels degenerative conditions such as diabetes, obesity and cancer. In the last 50 years we've learned the hard way that feeding biologically inappropriate, low-fat, high-carb diets do not create health in pets. In fact, chronic inflammatory and degenerative diseases have reached epidemic levels, all related to diet and lifestyle, in my opinion.
Further, low-quality proteins and fats (not fit for human consumption), when processed at high temperatures, create cancerous byproducts like heterocyclic amines.
The low moisture content of dry food is also problematic, especially for cats. Dry cat food provides only about one-tenth the amount of moisture cats receive from prey animals, living foods and even commercial canned diets, which puts significant stress on their kidneys and bladder.
Dogs also tend to become excessively thirsty when fed kibble exclusively. The carb-heavy nature of dry food, along with the tendency of pet parents to overfeed, is also a significant factor in rising rates of pet obesity. Most dogs and cats will thrive when given fresh, whole foods that mimic their ancestral diet, but unfortunately, many must make do with entirely processed, largely inferior alternatives. Your pet may have adapted to this diet, but it's a recipe for chronic disease.
As I mentioned earlier, the danger of salmonella poisoning from pet food is primarily a risk to the humans serving the food, not the animals eating it. Healthy pets are able to handle a much higher bacterial load than their owners. If you feed your pet kibble (which again, I do NOT recommend), the following simple handling precautions should keep you and your family safe from contamination:
✓ Wash your hands thoroughly after handling any pet food or treats.
✓ Don't allow very young children, elderly people or those who are immunocompromised to handle pet food or treats.
✓ Keep all pet foods and treats away from your family's food.
✓ Do not prepare pet foods in the same area or with the same equipment/utensils you use to prepare human foods.
✓ Do not allow pets on countertops or other areas where human food is prepared.
✓ Feeding pets in the kitchen has been identified as a source of infection. If you can arrange to feed your pet in an area other than your kitchen, consider doing so. Alternatively, feed your pet as far away from human food preparation areas as possible.
I don't recommend feeding your furry family member a commercial pet food with special additives designed to control salmonella. I'm an advocate of wholesome, natural diets for pets (and people).