According to a Tufts University study,
For dogs with dominance aggression, the addition of tryptophan to high-protein diets or change to a low-protein diet may reduce aggression. For dogs with territorial aggression, tryptophan supplementation of a low-protein diet may be helpful in reducing aggression.
Read the complete Tufts study in this PDF
Tryptophan is an essential amino acid which the body (canine or otherwise) can’t make on its own. It must be ingested in foods such as red meat, dairy, some seeds and even oats. Once ingested, tryptophan morphs into serotonin, which you may have heard is a natural mood enhancer and sleep aid.
If a dog is low in tryptophan levels, he’s also low in seratonin. A lack of seratonin has been linked to more aggressive, anxious behavior in dogs.
We have also been told by equine enthusiasts that the same principle applies to horses. Oftentimes, nervous horses are given tryptophan supplements before a competition to help calm them down.
Adding Tryptophan to Your Tripawd’s Diet
The only way to know if tryptophan will decrease your dog’s aggression is to try it. Researchers at Tufts found that a twice daily dose of 10mgs per kilo, significantly reduced “territorial and dominance aggression” in dogs.
While you can try introducing tryptophan-laden foods to your dog’s diet, the easiest way to get it is through a number of supplements like the ones you see here.
Be aware that side effects can include diarrhea and vomiting, so please check with your vet before use.