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Dr. Lewellen is Medical Editor for Advanstar Communications.
Fresh from the 2016 Nestle Purina Companion Animal Nutrition Summit: Exploring the impact of fatty acids and probiotics on anxiety in your canine veterinary patients.
The path to serenity is through the stomach? (Getty Images)
It is well-known that one of the top reasons dogs are relinquished to shelters is for behavioral issues. Many of these owner-dog relationship-threatening behaviors are a direct result of anxiety experienced by the dog. Although the number may be higher, some have estimated that 29% of pet dogs exhibit signs of anxiety.1 Ragen T.S. McGowan, PhD, of Nestlé Purina Research, presented some cutting-edge information on potential new treatments for canine anxiety at the 2016 Nestlé Purina Companion Animal Nutrition Summit.
When clients choose to treat rather than relinquish a dog exhibiting anxious behavior, behavior modification techniques, pharmaceutical intervention and sometimes pheromone exposure are the current staples of treatment. Is another avenue of intervention addressing anxious patients' nutrition?
A small number of studies on herbal,2 milk3,4 or fish derivative5 supplementation and amino acid or protein level manipulation6-8 have lent support to the theory that diet may have a positive impact on problematic behavior in dogs. Dr. McGowan proposed that, “Altering diet to manipulate the availability of precursors for the hormones and neurotransmitters that regulate behavior has merit as a means to mitigate many behavioral issues.”9 She presented information about two promising therapeutics that her research team had studied.
Diving into the fish oil factor
The precise mechanism by which omega-3 fatty acid exerts effects on behavior is not known. However, fatty acids have been proven to have antioxidant and anti-inflammatory effects as well as to modulate neurotransmitters and to affect neuroplasticity. In fact, fatty acids have been found to influence the same pathways that antianxiety medications do, most notably fluoxetine, a commonly prescribed treatment for anxiety disorders in dogs.10
In a study of 24 dogs, Dr. McGowan's team found that, “from both a behavioral and physiological standpoint, increased intake of fish oil had a calming effect on anxious dogs.”11 There is a plethora of evidence in the literature that supports using fish oil as a potential reliever of depression, anxiety, and hyperactivity in numerous species. It appears that this may hold true for dogs, as well.
Scrutinizing bacterial influence
The “gut-brain axis.” Have you heard of it? It is generally recognized that the gut and the brain are engaged in constant bidirectional communication through this axis. Dr. McGowan says there is now robust evidence that vagal pathways within the enteric nervous system (gut) transmit signals from the gut microbiota to the central nervous system (brain).12 She also says, “There is mounting evidence that in the literature that manipulation of the gut microbiota can influence anxious behavior specifically.”13-16
A promising bacterium that Dr. McGowan's team studied is Bifidobacterium longum. A few studies have found that exposure to a probiotic blend containing B. longum alleviated psychological stress in human volunteers and reduced anxiety-like behavior in rats.17 Studies have also shown that this anxiolytic effect is achieved through the vagal pathway.12 In Dr. McGowan's own study in 24 dogs, they found that, “From both a behavioral and psychological standpoint B. longum had an anxiolytic effect on anxious dogs.”11
Digesting the findings
“Our understanding of the impact of diet on anxious behavior is in its infancy,” says Dr. McGowan. “Although there are a handful of studies available in the literature, they are not without confounds and limitations.” However, given the growing body of evidence that nutrition can play a role in behavior, our obligation to relieve animal suffering, and the potential seriousness of the consequences of anxious behavior in dogs, it stands to reason that we should keep ourselves abreast of promising developments in the treatment of canine anxiety disorders. So stay tuned!
1. Denenberg S, Landsberg, GM, Blizzard T. Prevalence of fearful and anxious behaviors in dogs in the United States, in Proceedings. ACVB/AVSAB Veterinary Behavior Symposium, 2013;50-51.
2. DePorter T, Landsberg GM, Araujo JA, et al. Harmonease chewable tablets reduces noise-induced fear and anxiety in a laboratory canine thunderstorm simulation: A blinded and placebo-controlled study. J Vet Behav 2012;7:225-232.
3. Beata C, Beaumont-Graff E, Diaz C, et al. Effects of alpha-casozepine (Zylkene) versus selegiline hydrochloride (Selgian, Anipryl) on anxiety disorders in dogs. J Vet Behav 2007a;2:175-183.
4. Palestrini C, Minero M, Cannas S, et al. Efficacy of a diet containing caseinate hydrosylate on signs of stress in dogs. J Vet Behav 2010;5:309-317.
5. Landsberg GM, Mougeot I, Kelly S, et al. Assessment of noise-inducing fear and anxiety in dog: Modification by a novel fish hydrolysate supplemented diet. J Vet Behav 2015;10:391-398.
6. Dodman NH, Reisner I, Shuster L, et al. Effect of dietary protein content on behavior in dogs. J Am Vet Med Assoc 1996;208:376-379.
7. DeNapoli JS, Dodman NH, Shuster L, et al. Effect of dietary protein content and tryptophan supplementation on dominance aggression, territorial aggression, and hyperactivity in dogs. J Am Vet Med Assoc 2000;217:504-508.
8. Bosch G, Beerda B, Beynen AC, et al. Dietary tryptophan supplementation in privately owned mildly anxious dogs. Appl Anim Behav Sci 2009;121:197-205.
9. Bosch G, Beerda B, Hendriks WH, et al. Impact of nutrition on canine behaviour: current status and possible mechanisms. Nutr Res Rev 2007;20:180-194.
10. Jazayeri S, Tehrani-Doost M, Keshavarz SA, et al. Comparison of therapeutic effects of omega-3 fatty acid eicosapentaenoic acid and fluoxetine, separately and in combination, in major depressive disorder. Aust N Z J Psychiatry 2008;42(3):192-198.
12. Bercik P, Park AJ, Sinclair D, et al. The anxiolytic effect of Bifidobacterium longum NCC3001 involves vagal pathways for gut-brain communication. Neurogastroenterol Motil 2011;23:1132-1139.
11. McGowan RTS. “Oiling the brain” or “Cultivating the gut”: Impact of diet on anxious behavior in dogs. in Proceedings. Nestlé Purina Companion Animal Nutrition Summit, 2016:87-93.
13. Collins SM, Kassam Z, Bercik P. The adoptive transfer of behavioral phenotype via the intestinal microbiota: experimental evidence and clinical implications. Curr Opin Microbiol 2013;16:240-245.
14. Bruce-Keller AJ, Salbaum JM, Luo M et al. Obese-type gut microbiota induce neurobehavioral changes in the absence of obesity. Biol Psychiatry 2015;77:607-615.
15. Diaz Heijtz R, Wang S, Anuar F, et al. Normal gut microbiota modulates brain development and behavior. Proc Natl Acad Sci USA 2011;108(7):3047-3052.
16. Neufeld KM, Kang N, Bienenstock J, et al. Reduced anxiety-like behavior and central neurochemical change in germ-free mice. Neurogastroenterol Motil 2011;23:255-264.
17. Messaoudi M, Lalonde R, Violle N, et al. Assessment of psychotropic-like properties of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in rats and human subjects. Br J Nutr 2011;105:755-764.