In part one of the raw meat-based diet series, I investigated and explained a few myths associated with raw meat-based diets – including how dogs are far removed from wolves and therefore don’t need to eat a ‘natural’ or ‘ancestral’ diet as often suggested, how grains are not bad ‘fillers’ and why they can be important in a diet. In the next of the series, I have been asked is raw food ‘best’ for dogs.
Table of contents
I am going to burst that bubble
I truly do not believe anyone should claim there is a ‘best’ food. Every dog is individual and so are their nutritional needs, what suits one dog may not suit another. So, as per the last article where I dispelled some common raw food myths used to create a negative commentary around commercial dry/wet diets, this article also does not aim to tell you what is good and what is bad in pet food. It does aim to use evidence to ensure owners who are thinking about, or do feed, a raw meat-based diet do so while taking all considerations into account including the evidence for its benefits, and the potential cons.
What we do know
We do know however, that there are some commercial foods, whether wet, dry, cooked or raw, whose formulations are more likely to be good quality because the companies use veterinary nutritionists (PhD or Board Certified), feeding trials and evidence to back up their choice of formulations, feeding trials are massively important to understand who formulations work in ‘real life’ circumstances. There are even some formulations that may appear to be complete and balanced on paper; but that, when applied to living animals, begin to fall short.
No food choice is the ‘best’; all feeding choices have pros and cons
The reason many veterinary surgeons do not advise raw is because of the wider implication of the diet on the health of the patient. But also those coming into contact with them. In this article we aim to investigate the claim that raw is ‘best’; so owners can understand the evidence, or lack of, behind feeding raw.
Benefits of raw
Anecdotal benefits for the diet include improvement in coat and skin; elimination of breath, body, and faecal odour; improvement in energy, behaviour, and immunity; and a reduction in medical conditions including allergies, arthritis, pancreatitis, dental disease, and parasitism. However, these potential health benefits have not undergone thorough scientific evaluation yet.
The WSAVA states that there is no evidence that raw meat-based diets provide health benefits over commercial or balanced homemade cooked diets. However, there is growing evidence that feeding raw meat can be a health risk both for the pet and the owner. And this is something we should consider going forward.
Possible benefit for uroliths (bladder stones)
Investigators in a study found indications of lower calcium excretion in urine of dogs eating a commercial raw diet, compared with excretion in dogs eating a commercial dry extruded diet. This could indicate it may be beneficial for dogs prone to calcium oxalate urolithiasis. However, the raw diet contained considerably more water than the dry extruded diet. So it is difficult to interpret the importance of these results. It did not compare against a veterinary ‘prescription’ urinary diet or wet diet. Although this is a potential positive avenue further research is required in this area.
Digestibility
A common benefit stated by proponents of raw food feeding is in reference to digestibility and bioavailability of raw feeding. Studies have documented high digestibility of raw meat diets fed to exotic and domestic carnivores. This increase in digestibility could result in decreased feed intake and faecal output; aiding in overall management and husbandry which is very positive. Although heating can have several negative effects that decrease protein quality in a finished product by altering the functional and structural properties of muscle proteins, thermal processing has the potential to influence the digestibility both negatively AND positively, depending on the processing conditions.
One study concluded that ‘although there is evidence for improved digestibility of proteins in raw meat-based diets, compared with digestibility of proteins in extruded diets, the clinical effects of this difference are unclear and require further study.’
Does heating destroy digestive enzymes?
It has been suggested that this action reduces the nutritional quality of the ingested food. Essentially, that cooking or processing in any way reduces the nutritional value. Some have argued that the digestive enzymes in fresh food enhance biological availability and that heating (either by cooking or in the processing of commercial diets) depletes these enzymes.
The theory in one human study hypothesised that vital enzymes in ingested food interact synergistically (together with) with enzymes within the human body and enzymes in the digestive tract. It was suggested that alterations in food enzymes induced by processing such as heating, irradiation and the addition of chemical additives have been proposed to create a decrease in metabolic availability of nutrients, with the long-term consequence being disease.
Along the same line as this hypothesis, upsettingly some claim that commercial dry/wet diets cause illnesses, and believe that vets are promoting these diets to make more money – this is unsubstantiated. It was concluded in the particular study noted above that there is no direct evidence that lack of enzyme synergy leads to any disease processes and that the role of enzyme synergy has not been studied in sufficient detail to predict its biological significance.
So, while digestibility may be a positive in raw diets and some pets will thrive on the increased digestibility. This does not mean that commercial cooked / processed are bad.
Dental health – cleaner teeth
Another demonstrated health benefit is that raw bones given as chews reduce calculus (tartar) – as do other hard/abrasive chews. This is a positive finding as many dogs in the UK suffer from dental disease. Chewing is also very stimulating behaviour for many dogs and is really positive behaviour for them to engage in for boredom, anxiety and more.
However, this study has not yet been followed by an assessment of dental health at sub gingival (below the gum line) level, which is more appropriate when examining true dental health in dogs such as the use of dental X-Rays and examination under general anaesthesia. Furthermore, many commercial raw diets do not include intact bone. These may be given by people feeding a raw diet as an additional supplement.
There is also the concern that chewing bones, particularly weight-bearing bones such as knuckle bones, increases painful tooth fractures – veterinary dentists do not recommend using them for this reason. If bones of inappropriate shape and size are given we also have a risk of gastrointestinal issues such as foreign body obstruction or GI perforation. Overall, the evidence on raw bones is weak due to a serious risk of bias caused by limitations in the experimental design. Furthermore, weaknesses in reporting meant this research was difficult to fully appraise.
Dental health – reduced dental disease?
The reduction of calculus does not translate into reduced periodontal disease. Indeed, wild canids and felids, and feral cats, eating wild prey have high rates of tooth fractures and periodontal disease. Wild carnivorans have a high rate of tooth fractures that, across species, correlates with the amount of hard material, e.g., bone, in their diet. A study in foxhounds fed raw carcasses, including raw bones, showed that they had a high prevalence of tooth fractures, the skulls of African wild dogs eating a “natural diet”, also showed evidence of teeth wearing (83%) and fractured teeth (48%) and free-ranging maned wolves in Brazil on oral examination revealed crown fractures.
It has been concluded that considering the weak evidence on raw bones and lack of evidence on other types of raw treats, veterinarians and veterinary nurses should be cautious when recommending raw treats to support periodontal health in dogs.
Overall, one review by Davies et al (2019) stated:
Claims for improved oral health in diets with raw bones find support in studies showing less calculus among feral or wild dogs and cats yet, on balance, the limited published evidence does not support claims of reduced periodontal disease with raw feeding.
Concerns with raw meat-based diets in dogs: Why raw food might not always be ‘best’
Concerningly in a survey about raw feeding only 1% of owners acknowledged the possibility of health risks associated with this kind of diet. Any diet, whether raw or dry, has both beneficial and harmful effects. The important consideration is weighing up the benefits against the risks and analysing the evidence to ensure we are not putting our pet or ourselves and others at risk.
If you home prepare…
Health risks associated with raw diets include various diseases resulting from nutritional deficiencies or toxicities; the vast majority of home prepared diets, whether cooked or raw, fail to meet nutritional standards. This is why it is essential to use a board-certified veterinary nutritionist to guide your recipes if you choose to home prepare.
Interestingly a study into homemade diets in dogs found them to be rarely balanced leading veterinary professionals to worry about the short and long-term implications this diet may have on companion animals’ health. Although ‘home-made’ doesn’t necessary correlate with ‘raw feeding’ as there are commercial brands available a percentage of raw feeders do make their own formulations at home. So using a board-certified veterinary nutritionist to support you is essential. Many online recipes are not balanced.
One study by Pedrinelli et al stated:
A large percentage of nutritional imbalances was verified in the recipes investigated in the present study, exposing dogs and cats fed them to nutritional problems, compromising health and longevity.
Zoonotic infections
Dogs and cats, raw-fed or not, carry zoonotic (germs which can spread from animals to humans) pathogens, and raw feeding increases carriage of zoonotic and potentially antibiotic-resistant bacteria.
Importantly, freezing raw meat may not kill all of these bacteria. And the risk is not fully mitigated by food-preparation hygiene measures because some bacteria colonise raw-fed pets, which shed them around the home. Ensuring you have a fully traceable source to ensure temperature was controlled appropriately at all points of the process is necessary, any discrepancy in this while being packed or transported can increase the risk.
Foodborne bacteria
Pathogenic bacterial contaminants in raw meat and poultry products sold for human consumption varies greatly, overall prevalence of 10 to 20% is frequently observed for raw human edible products being contaminated with Campylobacter, Escherichia coli or Salmonella species. Just because a food claims to be ‘human grade’ does not make it safe; nor does it mean that much because meat used in animal food cannot be meat that has been removed from the human food chain because of disease etc.
These organisms do not always make pets ill, they may become “asymptomatic carriers”, meaning they can spread bacteria which are harmful to humans without showing any signs. There are published reports of bacterial illness and fatality in pets and humans associated with raw-fed pets. Studies have not yet been done to determine to what extent raw feeding pets increases human or pet morbidity, disease and mortality, however so we do need more evidence of this in future to determine significance.
The problem with public health
Although many believe that good hygiene practices will mitigate these issues this may be hard to achieve. A study found that standard methods of cleaning and disinfecting food bowls were minimally effective at eliminating Salmonella: this included soaking with bleach and cleaning in a dishwasher.
Several government and veterinary agencies have issued statements regarding raw food and concerns over public health citing:
- Feeding pets raw foods is not in agreement with their goal of protecting the public from significant health risks (FDA)
- That they discourage feeding raw foods to dogs and cats because of salmonellosis risk and other infections to both pets and owners
- Cautioned regarding the health risks associated with raw feeding and recommended clients work with their veterinary surgeon to determine if feeding a raw diet is the most appropriate choice
Microbial contamination, by either bacteria or viruses, is the most frequently documented disadvantage of feeding raw feeding. Specifically, Salmonella spp have received the most attention; however, other pathogenic bacterial contaminants include Escherichia coli, Listeria, Clostridium, and Campylobacter spp. Other worrying contaminants include tuberculosis infections in cats.
Dogs possess some physiological adaptations that may allow them to tolerate relatively high levels of microorganisms in their diet and may not frequently exhibit clinical illness when colonised by potentially pathogenic bacteria. However, it has been documented that dogs have experienced clinical illness with raw food associated pathogenic infection. Concerns also lie in the zoonotic risk to people, most notably children, elderly or the immuno-compromised members of society who may be at increased risk. Owners should consider this risk carefully if their raw-fed pet ever has contact with anyone in these groups, even if the animal appears healthy.
Parasites and Protozoa
There are steps we can take to help mitigate the risk of parasites in raw food. Studies have shown that adequate freezing at the right temperature and for the right amount of time can remove most parasitic risks. It has been suggested that the ideal freezing time is a minimum of −18°C for 10 days.
Another zoonotic concern includes Echinococcus (hopefully not in the UK!); a Hydatid tapeworm that dogs can pick up if they are fed raw carcass meat and offal. Concerningly, it has been attributed to a rise in human alveolar echinococcosis cases in Canada. Alveolar echinococcosis is a zoonotic cestode infection which is usually fatal in the absence of treatment. In one small study of human alveolar echinococcosis, risk factors included those that ate eat carrion or prey. Although no link has yet been proven it is thought the rise is due to the urbanisation of coyotes in the area and is an area we need more studies into.
Other parasites and protozoa associated with raw carcass includes Taenia, Neospora caninum, sarcocystis and Toxoplasma gondii and even Linguatula serrata, found recently in a UK dog and suspected to be from imported raw meat.
These parasites and protozoa have implications for our food chain and livestock. So vigilantly picking up faeces and rigorous and regular worming with prescription worming products is of vital importance. These are mainly caught via carcass ingestion, so if your dog is a scavenger on walks – whether raw fed or not – we must follow these recommendations.
Antimicrobial resistance
According to the Centers for Disease Control and Prevention (CDC) “antibiotic resistance is one of the biggest public health challenges of our time”. This is concurred by the World Health Organization (WHO) that describes antibiotic resistance as “one of the biggest threats to global health, food security, and development today.”
Concerningly in one study looking into raw-frozen samples they found that they all carried bacteria that are resistant to many antibiotics, including standard antibiotics that healthcare professionals prescribe regularly.
The authors of the study stated that, “the close contact of pets with humans and the commercialization of the studied brands in different EU countries pose an international public health risk if transmission of such strains occurs between dogs and humans.”
Many dogs do well – but care must be taken
Although of course it is possible to create a raw diet for dogs that is nutritionally balanced for their needs, risks do exist, and it’s important that they aren’t understated, or dismissed without proper consideration. As with any dog diet – not all commercial raw foods are made equal so talking to a board-certified veterinary nutritionist, veterinary professional or looking into a Pet Food Manufacturers Association (PFMA) registered brands can help to guide your decision.
Conclusion
Many dogs do well on raw. But this does not mean we should dismiss the wider issues associated with it. The common statement that raw is ‘best’ is unfounded. No diet is ‘best’, they all have positives and negatives that we need to weigh up.
If raw feeding is undertaken lightly, it can not only have implications for your pets but also for your family, the public and the food chain too.
There are many benefits perceived by advocates, and some dogs do exceptionally well on raw feeding, experiencing minimal issues; this is really positive. However, feeding raw diet does carry risks – we really must take care. Weighing up the benefits against the risks should be part of choosing any pet’s diet, because the health of our animals and our human families is of the utmost importance.
Further reading:
Discussion