In human nutrition, we understand that food affects our mood and behaviour – consider how children behave after eating brightly coloured sweets or how “dull” your thinking becomes when you miss a meal.

Increasingly, we are realising the benefits of eating a wide variety of fresh, whole foods and eliminating artificial flavours, preservatives, and compounds.

In animal studies too, there is evidence that diet can influence our dogs’ behaviour in the following ways. (de Leeuw et al 2008, Bosch et al 2009)

Tendency to react aggressively, fearfully or calmly

Animal studies using rats have shown that when hungry the rats exhibited increased levels of anxiety. Likewise, in dogs, studies show that hunger and high feed motivation elicits undesirable behaviours. When dogs are fed a high fermentable fibre diet they displayed lower levels of activity and repetitive behaviours than dogs fed a lower fibre diet. The study concluded that anxiety may be influenced by feelings of satiety. (Bosch et al 2009, Bosch et al 2007)

Behaviour results from signal detection, transmission and processing in the central nervous system. It is modulated by chemical messengers such as neurotransmitters and hormones. Amino acids are required to synthesize enzymes and other proteins that are precursors of neurotransmitters and hormones. In animal studies, dietary tryptophan, the precursor to serotonin, has been shown to positively influence animals’ behaviour. Studies have reported a reduction in aggression and self-mutilation, enhanced exploratory behaviour, and influence animals’ tolerance to stress. Diets supplemented with tryptophan appear to reduced aggression in dogs but had no effect on hyperactivity. (Bosch et al 2007, de Napoli et al 2000, Weld et al 1998)

Dogs displaying aggressive behaviour have been found to have a higher omega 6 to omega 3 ratio than non-aggressive dogs. This study found that when dogs are fed a low fat diet, their central serotonergic activity reduced. It concluded that low omega 3 status may affect serotonergic function in the central nervous system. (Re et al 2008, Bourre 2006)

Ability to learn and retain skills

Learning abilities in rodents fed omega 3 deficient diets were decreased. In these same subjects, increased aggression and anxiety was also observed. Behavioural changes such as poor memorisation and habituation, defensiveness and anxiety, and neuro-muscular co-ordination was observed in rodents fed an omega 3 deficient diet. A diet high in omega 3 increases alertness and learning abilities in mice. (Bourre 2006, Bosch et al 2007)

Willingness to interact in a desirable way with humans and their environment

A study of shelter dogs investigated the effects of human contact combined with a high quality diet comprises animal derived food sources on dogs’ behaviour. The study found that combining positive human contact with a high quality diet reduced escape attempts in behaviour tests and better enabled dogs to benefit from human contact. (Hennessy et al 2002)

Here are some points to consider when looking at your dogs’ diet and its effects on their behaviour and general health:

• Quality – Food source quality directly impacts nutritional quality. Protein is a good example. The quality of protein is measured by three factors: (1) the concentration of essential amino acids, (2) the digestibility of the protein and (3) the bioavailability of amino acids. (Gilani et al 2005) Protein from animal sources is recognized as being higher quality than from grain or legumes.

• Availability – The way our dogs’ food is processed (e.g. baked, steamed, extruded, and pelletised) affects the availability of the nutrients. The less a food is processed, the more available the nutrients such as protein, vitamins, antioxidants and fats. (Murray et al 1997, Singh et al 2007, Rawson et al 2011)

Food combination also affects nutrient availability. When all ingredients are mixed together, compounds in some foods interact with others. As an example, phytates found in grains have been shown to reduce zinc absorption and calcium retention. (Billinghurst 1993, Fredlund et al 2006)

• Artificial additives – Human studies indicate a link between artificial flavours, preservatives and colouring and increased hyperactivity and educational difficulties. (McCann et al 2007) Similarly, in animal studies, exposure to artificial food additives resulted in hyperactivity, learning difficulties, repetitive behaviours and impaired social behaviours. (Schultz et al 2008, EFSA 2011)

• Products of processing – The way our dogs’ food is processed can also create “products” or compounds that are foreign to the dog’s body. These products reduce nutrient availability and may be implicated in undesirable behaviour and longer term health issues. For example, Maillard reactions between proteins and sugars reduce the nutritional value of protein. Some vitamins may also be lost. (Singh et al 2007, Davis & Williams 1998, Williams et al 2006)

Full Stride works with you to tailor a diet plan to suit your dog and your lifestyle and budget. Please contact me at jlconlon@fullstride.com.au. to see how small diet changes may improve your dog’s wellbeing.

You can also stay up to date by following Full Stride on Facebook – https://www.facebook.com/FullStrideCanineMassageTherapy/

Until next time, enjoy your dogs.

Sources

Billinghurst, I (1993), Give your dog a bone:the practical common sense way to feed dogs for a long and healthy life, Warrigal Publishing, Bathurst NSW.

Bosch, G., Beerda, B, Hendriks, W.H, van der Poel, A.F.B & Verstegen, M.W.A. (2007) “Impact of nutrition on canine behaviour: current status and possible mechanisms.” Nutrition research reviews 20.02: 180-194.

Bosch, G., Beerda, B., van de Hoek, E., Hesta, M., van der Poel, A. F., Janssens, G. P., & Hendriks, W. H. (2009). Effect of dietary fibre type on physical activity and behaviour in kennelled dogs. Applied Animal Behaviour Science, 121(1), 32-41.

Bourre, J. M. (2006) “Effects of nutrients (in food) on the structure and function of the nervous system: update on dietary requirements for brain. Part 2: Macronutrients” The Journal of Nutrition, Health & Aging, Vol 10, No. 5: 286 – 399

Davis, P.J & Williams, S.C (1998) “Protein modification by thermal processing” Allergy 53 (Suppl 46): 102 – 105
De Leeuw, J. A., Bolhuis, J. E., Bosch, G., & Gerrits, W. J. J. (2008). “Effects of dietary fibre on behaviour and satiety in pigs.” Proceedings of the Nutrition Society, 67(04), 334-342.

De Napoli, J.S, Dodman, N.H, Rand, W.M & Gross, K.L, (2000) “Effect of dietary protein content and tryptophan supplementation on dominance aggression, territorial aggression, and hyperactivity in dogs” Journal American Veterinary Medical Association Vol 217, No 4:504-508

European Food Safety Authority, 2011 “Scientific opinion on the re-evaluation of butylated hydroxyanisole – BHA (E 320) as a food additive”, EFSA Journal 2011: 9 (10): 2392

Fredlund, K., Isaksson, M., Rossander-Hulthén, L., Almgren, A., & Sandberg, A. S. (2006). Absorption of zinc and retention of calcium: dose-dependent inhibition by phytate. Journal of Trace elements in Medicine and Biology, 20(1), 49-57.

Gilani, G. S, Cockell, K.A. & Sepehr, E (2005). “Effects of antinutritional factors on protein digestibility and amino acid availability in foods.” Journal of AOAC International 88.3: 967-987.

Hennessy, M. B, Voith, V.L, Young, T.L, Hawke, J.L, Centrone, J & McDowell, A.L (2002) “Exploring human interaction and diet effects on the behavior of dogs in a public animal shelter.” Journal of Applied Animal Welfare Science 5.4: 253-273.

McCann, D., Barrett, A., Cooper, A., Crumpler, D., Dalen, L., Grimshaw, K.,& Sonuga-Barke, E. 2007, “Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomised, double-blinded, placebo-controlled trial.” The Lancet, 370(9598), 1560-1567.

Murray, S.M. Patil, A.R. Fahey, G.C. Merchen, N.R. & Hughes, D.M. (1997) “Raw and rendered animal by-products as ingredients in dog diets” Journal of Animal Science 75: 2497 – 2505

Rawson, A, Patras, A, Tiwari, B.K, Noci, F, Koutchma, T, & Brunton, N (2011) “Effect of thermal and non thermal processing technologies on the bioactive content of exotic fruits and their products: Review of recent advances”, Food Research International, 44:1875-1887

Re, S, Zanoletti, M & Emanuele, E. (2008) “Aggressive dogs are characterized by low omega-3 polyunsaturated fatty acid status”, Veterinary Research Communications, 32: 225 – 230

Shultz, S. R., MacFabe, D. F., Ossenkopp, K. P., Scratch, S., Whelan, J., Taylor, R., & Cain, D. P. 2008. Intracerebroventricular injection of propionic acid, an enteric bacterial metabolic end-product, impairs social behavior in the rat: implications for an animal model of autism. Neuropharmacology, 54(6), 901-911.

Singh, S, Gamlath, S, & Wakeling, L. (2007) “Nutritional aspects of food extrusion: a review” International Journal of Food Science and Technology, 42:916 – 929

Weld, K.P. Mench, J.A, Woodward, R.A, Bolesta, M. S, Suomi, S.J & Higley J. D. (1998) “Effect of tryptophan treatment on self-biting and central nervous system serotonin metabolism in rhesus monkeys (Macaca mulatta).” Neuropsychopharmacology 19.4: 314-321.

Williams P.A, Hodgkinson, S.M, Rutherfurd, S.M & Wouter, H.H. 2006 “Lysine content in canine diets can be severely heat damaged” Journal of Nutrition, 136: 1998S-2000S