I hope you and your kitties have had a lovely week. In this week’s Sunday Read, by popular request, I’m going to delve into the subject of raw feeding.
I have to confess, when a few readers messaged me asking if I could look into the topic I thought it might be too simple for a Sunday Read – boy, was I wrong! In the last week I’ve been on a fascinating journey that has had me pinging back and forth between two really entrenched schools of thought. I’ve been in touch with people on both sides who passionately believe that what the other side is doing is harming their cats, and most importantly, read dozens – probably hundreds – of scientific papers to try and get my head around the subject and work out what we really can say with any certainty.
Until now I’d never really given much thought to my cats’ nutrition but researching this article was like opening a Pandora’s box. Now, finally, I think I’ve got to the heart of the matter, and I’m ready to share what I’ve found.
WHAT IS RAW FEEDING?
I first heard of raw feeding when I went to collect Lola as a kitten from her breeders. They raved about the benefits of a raw diet, and suggested that we order up ready-made raw food from an online supplier and store it in our freezer to feed her instead of wet (canned) food.
I planned to do exactly that, but I’m ashamed to admit that laziness prevailed and the convenience of getting wet food from the local supermarket pretty much put the brakes on my good intentions to keep Lola on the raw diet she’d been raised on.
It turns out that raw feeding (also known by the acronym BARF, for Biologically Appropriate Raw Food, or Bones And Raw Food diet) has recently taken off for cats, and there are both ready made commercial preparations and do-it-yourself recipes circulating for those willing to give it a go at home.
The idea is that cats in the wild consume a raw diet, so why not continue that in the home. Seems sensible, right?
WHAT ARE THE BENEFITS?
"Providing your cat with a diet modelled on what they would eat in the wild has many benefits, for you and your cat, including improved digestion; greatly reduced stool odor and volume; healthy coat, less shedding, fewer hairballs; increased energy; weight loss, if overweight; better dental health; better urinary health."
“These [raw] diets are widely touted by their proponents as being more appropriate than commercial pet foods and as resulting in improved coat quality, health, immune status and longevity: however, there currently are no objective data that support any of these claims.”
Advocates of raw food diets give a long list of potential benefits, but the truth is that there are virtually no modern studies that have tried to independently verify these claims (don't lose hope and stop reading though, it just means we have to work a little harder in this Sunday Read for our answers!). I’ve read people on forums saying that’s probably because there’s no one with a vested interest to fund them, since the pet food companies have such a stranglehold on the field. That may indeed be true (although it’s worth remembering that lots of other studies get funded for purely blue sky reasons – just look at past Sunday Reads).
THE POTTENGER CAT STUDY
Amazingly the only study which does seem to speak directly to the question of whether raw food can be beneficial was conducted over 75 years ago. It’s known as the Pottenger Cat Study. Dr Francis Pottenger was a physician at a sanatorium in California in the 1930s and 40s. When he wasn't looking after his patients with tuberculosis, he liked to do his own experiments to test theories on health and disease, and those experiments were often conducted on ex-laboratory cats.
For practical reasons, he started feeding a group of laboratory cats a diet of milk, cod liver oil and cooked meat scraps leftover from the sanatorium itself, but when the number of cats grew, he was forced to start feeding a second group on a different diet of raw meat scraps acquired from the local market (Pottenger, F., 1946, via Brink, P., 2002).
Before long he noticed a stark difference between the health of the two groups – the cats in the raw food group had glossier coats and recovered better from surgery. He hadn't set out to study their diet (he was interested in their adrenal hormones), but when he spotted the interesting trend he decided to refocus his study – following the fortunes of 900 cats fed raw and cooked diets over a period of ten years, and across three cat generations.
The cats fed a raw food diet maintained general good health. But the health of the group fed a cooked diet took a nosedive. They suffered from lethargy, their coats weren’t as glossy, and they recovered less well from routine surgery. As the generations wore on the symptoms became worse, with cats being born with skeletal malformations, succumbing to heart disease, organ failure, allergies and infections, until by the third generation they became unable to breed and died by the age of six months (Pottenger, F., 1946, via Brink, P., 2002).
The results of this study have been cited in recent times as evidence of the benefits of raw feeding (e.g. here, here and here). But we need to ask ourselves some questions. First of all, why aren't millions of cats around the globe that have been reared on cooked diets experiencing the same symptoms as Pottenger's cats? Pottenger asked these same questions himself, and hypothesised that there was a substance in the cats' food that was essential to their wellbeing, and that was being damaged by heat during the cooking process (Davidson, R. & Emlet, J. 2014).
We now know that that factor is taurine, a molecule that is essential for many biological functions (Davidson, R. & Emlet, J. 2014). We humans can make it but cats can’t – they have to get it from their food. The only problem is that it is inactivated by heat, so doesn't survive through the cooking process. Poor old Pottenger's cats were suffering from serious taurine deficiency:
"Pottenger’s main observations...correspond to published descriptions of taurine deficiency in cats...Taurine deficiency is a strong explanation for the symptoms observed by Pottenger in his cat studies."
All modern commercial cat foods now add taurine back in after the cooking process (European Pet Food Industry Federation, Nutritional Guidelines 2013), so that's why we don't see any of the ill effects that Pottenger documented in his study.
This is very good news for cats worldwide. But it does leave us at a bit of an impasse when it comes to working out if there are any benefits to raw feeding. Now we know about taurine, Pottenger's study doesn't seem as enlightening after all.
Luckily, all is not lost.
Instead we just need a new approach. Instead of asking whether raw food diets are better than commercial cooked diets (for which no studies have been done), why don’t we ask whether there’s anything wrong with eating a commercial cooked diet, and if so, whether raw feeding could fix those problems.
Now, we can get some answers.
IS THERE ANYTHING WRONG WITH COMMERCIAL CAT FOODS?
There is a big difference between the food we typically feed our cats and the diet that they would consume in the 'wild'.
Cats are what's known as 'obligate carnivores' which means that they have evolved to derive all or most of their energy and nutrients from eating meat. Because of this, their natural diet consists almost solely of fat and protein (the stuff that makes up muscles) with very little carbohydrate at all.
Commercially available foods look very different indeed:
"A bird or a mouse consists of approximately equal amounts of fat and protein and <5% carbohydrates. Commercial diets, however, contain on average 33% carbohydrates in dry food and 15% carbohydrates in canned [wet] food"
Because of their meat-eating history, cats lack several adaptations that other mammals have for digesting carbohydrates (more commonly found in grains and plants). For instance they don't have an enzyme that begins breaking down starch in their saliva like we do (Kienzle, E. 1993), although they can still use carbohydrate as an energy source.
So could forcing a cat's digestive system to contend with 'unnaturally high' levels of carbohydrate be causing them any harm?
The big accusation that's levelled at high carbohydrate foods is that they cause excess sugar to wash around in your cat's blood stream, eventually causing conditions like obesity and type II diabetes.
Now, normally I would take you through all of the studies one by one but there are too many in this area to cover them all (they are all listed and discussed in depth in this great review article though, which is free to access: Buffington, C. A., 2008). The important thing is that the overall picture from multiple studies is that eating a high carbohydrate diet doesn't seem to be linked to obesity or type II diabetes in cats.
"Current published evidence...does not support a direct role for diet in general, or carbohydrates in particular, on disease risk in domestic cats."
Certainly more research needs to be done, but so far all the signs point to the fact that those diseases are much more heavily influenced by a cat's genes, environment and activity levels than the exact amount of carbohydrate in their food. (Buffington, C. A., 2008)
ARE THERE ANY DRAWBACKS OR DANGERS TO RAW FEEDING?
By this point you might be thinking - sure, there's no strong evidence in favour of raw feeding, but I look after myself and try to know exactly what I'm eating, and I'd like to do the same for my cat too.
So if you decide to do this, are there any risks you should be aware of?
The first one is the difficulty in getting the exact balance of your cat's meal right. We've already seen what can happen when a cat is deficient in taurine, and you may think that by raw feeding you've got that covered. But taurine levels are highest in certain parts of the animal (such as in the organs and dark meat), and there has recently been a case in the literature where a breeder raised a kitten on chicken meat only, resulting in severe nutrient deficiency for the poor little cat.
"A 5-month-old castrated male Sphynx kitten presented with left hindlimb lameness shortly after adoption. Prior to adoption, the breeder had fed the kitten an exclusively raw chicken diet...The patient’s diagnoses included metabolic bone disease and feline central retinal degeneration, which can result from taurine deficiency."
This is a cautionary tale against just switching to a meat based diet without doing some serious research. But getting the balance right is possible. To make things easier, you can buy pre-prepared raw food diets that are already nutritionally balanced, or there are established recipes for you to make up yourself, that call for supplementation with key nutrients. It's just a case of making sure you do your research.
The other big risk is bacteria and viruses that may be hiding in your cat's food, and the risk they may pose to you and your cat. Let's just take your cat first. Although many claim that cats are virtually immune to diseases like Salmonella (e.g. here), and point to the fact that they can lick their rear ends without apparent harm, cats can in fact succumb to these diseases:
"Salmonellosis in cats is similar to salmonellosis in dogs and humans...Sources of Salmonella organisms in cats are various, but they are dependent on whether cats are indoor or outdoor cats. For indoor cats, the most likely exposure is con- sumption of food contaminated with Salmonella organisms, whereas outdoor cats may be exposed through scavenging and hunting, especially the hunting of birds."
So far, there has been one reported case in the literature of two cats from the same house developing salmonella after eating a raw diet. Sadly both cats died (Stiver, S. et al 2003).
WHAT ABOUT THE RISKS FOR HUMANS?
Growing concerns around the safety of raw food diets for pets have led the Food and Drug Administration (FDA) in America to do their own research. In a two year study they tested over 1000 samples of pet food for bacteria that could cause food borne illnesses.
"The study showed that, compared to other types of pet food tested, raw pet food was more likely to be contaminated with disease-causing bacteria."
The raw pet foods showed a much higher rate of positive results for Salmonella and Listeria than the dry foods they were tested alongside. These findings led the FDA to release a public safety message:
"Based on the study's results, CVM [the FDA's Center for Veterinary Medicine] is concerned about the public health risk of raw pet food diets...owners who feed their pet a raw diet may have a higher risk of getting infected with Salmonella and Listeria."
These are both potentially deadly diseases, especially for the immune compromised and young children, so this is not information to be taken lightly. If you do end up going raw, it's well worth reading their list of guidelines to reduce your risk of infection, including not letting your cat give you 'kisses' on your face (the full FDA advice guide is available here).
And that's it! Thanks for sticking with me on this grand tour through our current state of knowledge - I hope it gives you the tools and facts you need to make your own choice about your cat's diet.
If there's a subject you'd like me to investigate for you in a future Sunday Read, just drop me an email at firstname.lastname@example.org.
Have a great week ahead,