Lisa Weeth, a board-certified veterinary nutritionist and member of the WSAVA Global Nutrition Committee based in Los Angeles, reviewed the evidence on the efficacy and safety of various non-conventional pet-food diets. She recognised that concerns about the quality of commercial pet foods have led many pet owners to seek different approaches to pet animal nutrition in recent years.
Although Lisa insisted that she had no strong preference for any particular type of pet food, there was one exception – raw meat products. She could not recommend this approach as it posed a potential health risk both to the animal and to its human family members.
Dogs are fairly resistant to Salmonella
infection but food-borne disease could develop in very young or old dogs, as well as in those that are immunocompromised. Moreover, there was a significant risk that humans living under the same roof could develop a potentially serious infection, even when the raw food is handled with care and the dog bowl is washed separately to any other dishes. Bacteria are likely to be present in the dog’s saliva and can be transferred on to the owner’s face or be disseminated on surfaces all around the house, she warned.
Many owners, and even some veterinary practitioners, believe that freezing meat products will successfully eliminate the infection risk but there is good reason to challenge such claims. Many bacterial species will become dormant and stop reproducing but they can survive for extended periods at sub-zero temperatures and may be present on surfaces within the freezer as well as in frozen animal products.
Lisa Weeth noted the cluster of cases of human infection with Shiga toxin-producing E. coli detected by Public Health England in 2017. There was strong evidence that frozen raw dog food had been the source of the infections, one of which proved fatal. Another series of incidents in the United States resulted from contact with Salmonella-contaminated pig-ear-based dog chews and led to 21 people being hospitalised, she said.
Another major trend in pet animal nutrition over the past decade has been the growth in the popularity of home-cooked diets. Using fresh ingredients may potentially offer some nutritional benefits for dogs and cats, and the act of preparing and offering the food may help to strengthen the human–animal bond, she said.
However, there are significant drawbacks, she continued. There are potential risks when following this approach that it will not produce a suitably balanced combination of both major and minor nutrients, unless the owner seeks out and then follows the advice of a trained nutritionist. Other potential problems include selective consumption with the animal ignoring those ingredients that it doesn’t particularly like.
Another common issue with home-produced rations is “diet drift”, involving the owners changing the recipe for the home-cooked meals to match what they believe the pet wants, which can undermine efforts to produce a properly balanced diet. Any changes in the dog’s health or appearance are unlikely to be noticed by the owner but dietary deficiencies could diminish the pet’s quality of life or its longevity, she warned.
In the same session, Cecilia Villaverde, a board-certified veterinary nutritionist based in the Republic of Ireland, addressed the particular issues involved in providing a properly balanced diet for pets with kidney disease. She believed that commercially produced diets were preferable in these patients because of the difficulties in keeping control over key factors such as phosphorus levels and the overall pH of the ration when trying to follow a home-cooked recipe.
But it is not impossible to create a satisfactory maintenance diet at home and this strategy may even be preferred in cases where there are comorbidities that make standard commercial formulae less suitable.
Home-cooked meals may also be appropriate if owners are trying to encourage pets to eat when their appetite is poor. If clients are keen to follow this route, Cecilia Villaverde recommended using fattier cuts of meat like chicken thigh in combination with carbohydrates and necessary supplements. However, the importance of consulting a veterinary nutrition specialist before adopting a home cooked diet was highlighted by both speakers, and a proper custom-made recipe should be created taking the pet’s specific needs into account.
The two speakers were asked about their views on more unorthodox protein sources, particularly the insect/larvae-based products that have appeared on the European pet-food market.
Lisa Weeth believed that insect protein is very attractive from an environmental sustainability viewpoint and the amino acid balance in this particular source did appear to be reasonably good. “There’s not a lot of research on how digestible those insect proteins are, especially if they’re put into a commercial extruded diet: it’s a processed ingredient going into another more processed food [which is then] fed to dogs and cats. Is it healthy and sustainable for the animal? That is still a question mark.”
Cecilia Villaverde was asked about the prospects for pet foods made entirely with vegetable ingredients. She suggested that the answer depends on how the product is formulated, explaining that it can be tricky to get the amino acid profile right with plant-based ingredients and it is much easier to do so when starting off with an animal protein source.