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Aggression And Protein Content Of Food


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I'm going to preface this by noting that it may be a highly controversial topic. I am still in the process of searching for scientific literature on this topic (and unfortunately it seems there is very little, and the little there is are only very small studied).

 

We had our meeting with a certified behaviorist today and one of the things that was mentioned is that lower protein diets (under 20%) have been associated with less reported aggression in fear aggressive or territorial aggressive dogs. He did not have the study available, as no clients have ever asked to see it. I did a quick search after our appointment and I did indeed come across a very small number of studies comparing low protein with high protein (30%) diets for a short time (1 to 2 weeks), with each with study groups of only about 7 to 12 dogs. (ie: likely not a big enough study population or long enough duration to give strong evidence either way)

 

Now, the dilemma is this: I am very supportive of the nutritional value of raw feeding. Our raw food has been assessed to have 48% protein content, though at the moment we are mixing this half and half with a 24% protein kibble. Very roughly he's likely getting about 36% protein in his meals, though he also gets high protein treats such as bully sticks and dehydrated liver. He's very well muscled, has a soft and shiny coat, and never seems to be without energy when we engage him in play, or take him out for walks. He also LOVES eating this food, and certainly is not as enthusiastic about eating plain kibble.

 

However, the studies do suggest that decreasing protein level in food has improved the owner perceived level of aggression (ie: less aggressive). I won't get into the technical details here, but it is proposed that high protein diets decrease the amount of serotonin in the brain. Lower serotonin levels in the brain and cerebral spinal fluid have been associated with higher level of anxiety and aggression in canines, which unlike the dietary studies, is a much researched area.

 

In addition, these dietary studies only lasted 14 days maximum, so detrimental nutritional effects would not likely have been seen (or at the very least were not reported as endpoints in the studies).

 

It has been recommended to us to decrease dietary protein in addition to behavior interventions and reinforcing our leadership (essentially NILF). I'm in full support of all these suggestions except for changing his diet. I'm posting to open a discussion about the link between diet and behavior, and to see if anybody has anecdotal support for or against, or knows of any better scientific evidence for or against changing protein in diet and aggressive behavior.

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Guest Giselle

I have not seen convincing evidence, but I didn't do a thorough literature search. What are the articles you found that linked increased aggression to higher protein levels?

 

This is my opinion and mine only: Because I've seen how effective techniques and advanced skills can influence animals' behaviors much more than medication and/or food changes, the latter two issues are not of great concern to me.

 

I tried everything under the sun with Ivy. And I had a serious case of dog aggression on my hands. Ivy had an abnormality where she would not growl or warn. She went straight from silent staring to fatal attacks. I tried food changes. I tried medication. I tried nutriceuticals. In the end, what mattered most was my technique, my training methods, and my consistency. What matters most, in my opinion, is practicing over and over and over and over and over and over and over again. You have to practice the 'good' behaviors over and over until those neural pathways override all the dog's aggressive impulses.

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@Giselle,

 

Dietary protein is mentioned in a meta-analysis of specific nutrients and canine behavior in a 2007 publication in Nutrition Research Reviews

Abstract: http://journals.camb...ine&aid=1452580

Full text: http://journals.camb...1bc6fe8a66d382c

 

I believe the one that Kerry was referring to is this study in the AVMA (he mentioned that Dodman was one of the co-authors) but I only have access to the abstract (will need to get the boyfriend to see if he has access through his school)

http://avmajournals.avma.org/doi/abs/10.2460/javma.2000.217.504

 

So far that's all I've found, but I haven't had the time to do a serious search.

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Guest PiagetsMom

I'm currently working with a veterinary behaviorist with Maya, and I'll share her opinion on this subject, which I myself posted about several months ago after having a trainer make the suggestion that diet was related to aggression/reactivity.

 

When I broached the subject with the behaviorist, her feelings are that diet wouldn't be the first thing that she focused on.....or the second, etc., but when you've exhausted your other training and behavioral options, and have not found a solution, then she feels it would be something to consider and address to see if it helped.

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Don't you think it would be very odd that a high protein diet would cause behavioural problems in a canid? I suppose you could consider it the other way round and say, well, wild dogs need to be aggressive to survive, so the fact that a high protein diet is natural to a dog AND that it causes behavioural changes don't have to be incompatible statements, but ..

 

We - humankind - have been living with and around dogs for millennia now. Up till fairly recently, my guess would be that they were fed largely protein diets. And if you look at greyhound racing kennels, I don't know of a single one that feeds a low protein kibble - most don't, even for retired dogs. They all get the same dinner, if a little less of it. And greyhounds are one of the least aggressive breeds.

 

I personally think the truth is more likely the same as with oats and horses. If you keep an animal in top condition, and fed a high energy diet, you must then employ that animal, or suffer the consequences. A dog feeling fit and full of energy will usually become frustrated, and may find himself something fairly negative to do if he's not allowed to vent that energy. Horses that 'feel their oats' do not want to be restricted to a gentle walk, and may start to misbehave if you require it.

 

Add to that the fact that dogs aren't ideally suited to digest large amounts of carbs and the fact that we know what a deadening effect they can have on us (they can make people sleepy and sluggish) and we begin to talk, not about 'is a high protein diet bad for dogs?' but 'why do we feed so much carbohydrate to an animal which is largely a carnivore when it's less than optimum nutrition?

 

Just my opinion, but it seems logical to me that if you put a lot of effort into bringing a dog to prime fitness, and you don't give him enough to do, both mentally and physically, he's going to get frustrated. Could it simply be this that the studies appear to be finding - scant as they are?

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The plural of anecdote is not data

Brambleberry Greyhounds My Etsy Shop

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Guest Giselle

Thanks for the articles! I think the DeNapoli study is covered in the review paper, and I'm not particularly interested in the subtle nuances of the individual studies. So, I just read the first review one :)

 

Also, Silverfish, the first paper that Antisense posted suggests that carbohydrate-rich diets encourage the uptake of non-tryptophan proteins into skeletal muscle. This then increases the relative amount of tryptophan, which (due to enzyme kinetics) supposedly increases the amount of serotonin produced. While there are many other dietary approaches to theoretically raise tryptophan:other protein ratios, they seem to suggest that carb-rich diets are beneficial for boosting serotonin production.

 

At the end of the day, though, none of the studies are very robust. I am uncomfortable with the parameters they use to gauge "aggression" in pet dogs in the studies, and I am doubly concerned by the usage of "dominance aggression" (a term which, to my knowledge, has mostly been phased out in modern studies). It seems to me that the behaviors they tried to study weren't good indicators, the results weren't replicable, and the mechanisms are mostly unverified. So, is diet a concern in regards to aggression? Well, sure, it's always a concern. But, in terms of behavior modification? It's probably one of my least concerns. My two cents!

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While there may be no scietific studies, like silverfish said, look at the racing kennels. Racing in the U.S. has gone on for over 80 years and a high protien diet is essential. While there is an occasional fight it isn't an every day or every week happening. Their diet is 30% protein or maybe a little more. So I would say each kennel is a study unto itself.

 

You might occasionally get a dog, like Downing, that didn't like any dog and had to be turned out with the one dog he did get along with at a different time, but that is the exception.

 

Hopefully someone like Rachel, Dennis or one of the other people on GT that work in the kennels can comment.

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Also, Silverfish, the first paper that Antisense posted suggests that carbohydrate-rich diets encourage the uptake of non-tryptophan proteins into skeletal muscle. This then increases the relative amount of tryptophan, which (due to enzyme kinetics) supposedly increases the amount of serotonin produced. While there are many other dietary approaches to theoretically raise tryptophan:other protein ratios, they seem to suggest that carb-rich diets are beneficial for boosting serotonin production.

 

Which is probably the same mechanism which causes us to feel sleepy after a carbohydrate-rich meal. My point is that we are better suited to a carb-rich diet than dogs are, and giving it to a dog is pretty much like deliberately feeding them a less-than-optimum diet just to make them more to our liking.

 

Well, making a dog 'more to our liking' is OK, because a lot of what we do with our dogs is aimed at just that, but I'm not sure I like the idea of doing so by adjusting their metabolism/nutrition in a negative way. IMHO it's preferable - as PiagetsMom's behaviourist and Giselle said - to make them more to my liking by addressing their behaviour.

 

... and I am doubly concerned by the usage of "dominance aggression" (a term which, to my knowledge, has mostly been phased out in modern studies). It seems to me that the behaviors they tried to study weren't good indicators, the results weren't replicable, and the mechanisms are mostly unverified. So, is diet a concern in regards to aggression? Well, sure, it's always a concern. But, in terms of behavior modification? It's probably one of my least concerns. My two cents!

 

Exactly. And in fact I've heard more substantiated stories about dog foods containing large amounts of chemical additives (like colourings and preservatives) causing behaviour problems that about high protein foods doing so. Seems to me to be harking back to the days of 'if you let a dog taste fresh blood he'll become aggressive'. And our raw feeders would have something to say about that!

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The plural of anecdote is not data

Brambleberry Greyhounds My Etsy Shop

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Thank you for your input everyone.

 

I did find one more article, Effect of dietary protein content on behavior in dogs, and I believe this is actually the one that the behaviorist was referring to as Dodman is the primary author

http://www.ncbi.nlm.nih.gov/pubmed/8575968

 

Key findings being:

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

 

However, this statistical significant change was only found in a post hoc analysis... which is typical when the researchers found NO statistical significance when following their initial experimental proposal, and they tried to find something interesting by re-analyzing their data.

 

At least for me, this strongly suggests that diet is unlikely to result in significant behavior change.

 

 

It IS interesting however that in the DeNapoli study (posted link earlier, but here's a pubmed link http://www.ncbi.nlm.nih.gov/pubmed/10953712) the addition of tryptophan to the diet may be helpful in some cases of aggression (primarily fear based). I think JJ would approve of more turkey necks!

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I remember reading some articles on this on one of the nutrition groups I am on. As far as I know a lot of tryptophan studies have been done on pigs and rats...the ones on dogs have been inconclusive. From what I remember reading, it produces seratonin in gut fermentation, and needs to be taken with a soluble fibre to really work. Pigs and rats, being omnivores, have a longer digestive tract that would be more suited to this....dogs not so much. It does seem like increased tryptophan has sometimes shown a decrease in aggression, but I really think there are too many other factors here in the studies (ie. what other ingredients were in the food they fed, was it the placebo affect of the owners who just thought their dogs were calmer, or acted calmer themselves, thereby reducing aggression, etc.).

 

There are hundreds of thousands of dogs (including racing greys, racing sled dogs, raw fed dogs, grain free dogs) on high protein diets, I would imagine if it was a big deal their would be a lot more aggression!

 

As was already mentioned, I think training is the big factor here, although it also doesn't hurt to try things out if you are stuck.

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Guest Giselle

Of course, my personal anecdote is not equivalent to scientific fact. BUT this is a forum :) Personally, I think that there are sooooo many steps along this serotonin pathway that could be abnormal in an aggressive dog. Sure, we can increase the substrates and hope for more products, but I can't even tell if the intermediate steps are working correctly. Who knows if the receptors are working correctly? Is the electric impulse traveling down the nerve correctly? Is acetylcholine working? Are the calcium channels working? Are the vesicles releasing correctly? And, who knows if all the other neurotransmitters and hormones are working correctly! Again, this is just my personal anecdote, but I had Ivy on "trytophan-supplement" treats and an SSRI. It never hurts to try, but it sure didn't help us much. :dunno

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