Recently a Vet Nurse told me that she had heard in a lecture that raw feeding can cause aggression, I'm not sure if the lecture was from a kibble manufacturer or from a Vet Nurse TAFE course or similar but I thought this was a great opportunity to dive into this topic to dispel this myth. Back in the day, people used to think if a dog got the taste of blood it would make them aggressive - we know this isn't the case. Clearly, raw feeding doesn't make dogs aggressive as a broad generalisation, so let's see if there is any science that might be able to pin point where this myth originated from.
A 2012 study called 'Dietary hyperthyroidism in dogs' evaluated dogs with elevated plasma thyroxine concentration who were fed raw food before and after changing the diet. Hyperthyroidism is the production of too much thyroxine hormone. It can increase metabolism. Symptoms include unexpected weight loss, rapid or irregular heartbeat, sweating and irritability, although the elderly often experience no symptoms.
Six of the 12 dogs in the study showed clinical signs such as weight loss, aggressiveness, tachycardia, panting and restlessness while six dogs had no clinical signs. After changing the diet, the dogs were examined and they found that thyroxine concentration normalised in all dogs and clinical signs resolved.
So, what happened here? A very important sentence in this study is this: "Dietary hyperthyroidism can be seen in dogs on a raw meat diet or fed fresh or dried gullets"
You've probably seen dried gullets as treats in your local pet shop, these are called tracheas here in Australia. Some raw feeders may stuff these with a mix if meat and veggies etc. as an enrichment meal.
So, why might trachea's be an issue? Well, this is where it gets interesting!
The hormone thyroxine that I mentioned earlier is the main hormone secreted into the bloodstream by the thyroid gland and the thyroid gland is attached to the trachea. If the gland is not completely removed during processing then it is likely to be problematic. If your dog is eating a lot of these or regularly eating these, then this has the potential to cause Hyperthyroidism in your dog regardless of it is displaying clinical signs or not.
So, what about raw meat? The study also called that out?! Cheap mince mixes or lower grade suppliers will have trachea and their trimmings minced through. This practice used to occur in human grade meats but was made illegal a long time ago. As a raw feeding pet parent, you need to make enquiries as to what goes into your mince mixes, if you're buying budget minces then you're likely getting trachea in there. The question you want to ask is "Does this product contain tracheas?" If your dog is currently displaying any of the symptoms mentioned earlier, it would be a good idea to get your dogs bloodwork including thyroid levels checked. I get my dogs' bloods run 1-2 times a year because to me, it's just part of their maintenance and gives me an opportunity to get on top of anything in the early stages. The test my Vet orders is the IDEXX Gerd Canine Screening Profile , just make sure it includes Thyroid levels. At this time, none of my dogs or tested foster dogs have shown Hyperthyroidism in their blood work - I do avoid cheap minces because high fat minces lack nutrients and I want to avoid that. My dogs however, have had trachea from time to time, although not regularly.
Now, it's important to note, that this condition has also been linked to canned foods, the FDA put out an alert back in 2017 giving Vets the heads up and stated that animal food with elevated thyroid levels likely contains animal gullets (trachea) in which the thyroid glands were not completely removed. Would we now say that canned foods cause aggression? No, of course not, just like we wouldn't say raw feeding causes aggression. To state that a specific diet causes aggression in an animal would indicate that the communicator lacks education in nutrition and biology.
Whilst this study that was all the way back in 1996 was not based on raw diets, it looked at the effect of dietary protein content on behavior in dogs. They wanted to see if there were any behavioural changes when dogs were fed different protein diets being low (17%), medium (25%), or high (32%). Raw fed dogs typically fit into the high protein group BUT raw fed dogs consume protein largely from meat not from plant matter which is what dry food largely is so it's hard to know if this studies findings could be relevant. In this study, they took 12 dogs with dominance aggression, 12 dogs with hyperactivity, 12 dogs with territorial aggression, and 14 control dogs without behavioral problems. Dogs were fed each of the dry food diets for a 2-week period, and owners were instructed to score their dogs' behavior on a daily basis - owner reported data can be a bit iffy, but let us continue... Behavior of the dogs with dominance aggression, dogs with hyperactivity, and control dogs were unchanged by the dietary manipulations. Territorial aggression was significantly reduced when dogs were fed the low or medium-protein diet, compared with territorial aggression when fed the high-protein diet. Post hoc analysis indicated that this effect was attributable to a marked reduction in aggression in a subset of the group (n = 7) in which territorial aggression was a result of fear.
The results of this study suggest that a reduction in dietary protein content is not generally useful in the treatment of behavior problems in dogs, but may be appropriate in dogs with territorial aggression that is a result of fear. Low protein diets are detrimental to the dogs muscular condition so definitely are not recommended - did these dogs energy levels dive so low that they simply didn't have the energy to participate in their territorial behaviours? If we don't provide dogs with good amounts of protein their body will break down muscle tissue to generate it aka they cannabalise themselves. In addition to this, "protein restriction can result in impaired wound healing, diminished immune function, and lowered enzyme activities and cellular turnover.(1) The territorial aggression scores of dogs on low protein diets but supplemented with Tryptophan were further lowered in another study in the year 2000.
Now, to another concern...if you were to feed your dog rabbit meat for example, would your dog then want to kill your pet rabbit. No. Does your dog have prey drive (wants to chase moving objects) and therefore wants to chase rabbits and other things? Yes? Then they will do this regardless of the diet you feed them - this is genetics and it's your job to well research the breed/mixed breed of dog you're getting to learn about their traits before you bring them home and not put them into situations where their genetics will make decisions you don't agree with.
Food aggression known as 'resource guarding' is seen in dogs fed all diets. A dog who has a high value for what they are eating may show aggressive behaviours to those around them including humans and other animals. Bones and yummy treats can elicit this behaviour in dogs prone to this behaviour. If your dog shows any signs of resource guarding regardless of what diet they are on, you should contract the services of a suitably qualified trainer and/or behaviourist.
A raw diet can actually be beneficial to your dogs mental health, A 2018 study called The fecal microbiome and metabolome differs between dogs fed Bones and Raw Food (BARF) diets and dogs fed commercial diets found that microbial communities and metabolome vary significantly between raw fed and kibble fed dogs with raw feed dogs having higher diversity which is what is seen in healthy beings. We also know that because of the gut-brain axis that a healthy gut microbiome positively influences mental health.
There are many nutritional connections to positive mental health and this is a whole different blog, but let me tell you, feeding your dog a variety of whole foods that are species appropriate on rotation promotes good mental health - I will hopefully get around to writing more on the science of good mental health acquired from nutrition in the near future. My recommendations to any pet parent with aggression and anxiety challenges with their dog is to seek a suitably qualified professional who uses methods you're comfortable with and then team up with a canine nutritionist to help you tweak your dogs diet.
If you would like to learn more about how to feed a balanced fresh food diet to your dog, join us at https://www.facebook.com/groups/rawandfresh --- (1) https://www.whole-dog-journal.com/health/a-low-protein-kidney-diet-is-not-always-the-answer/