Our petfood expert Anton Beynen looks at the use of calming supplements in petfoods – do they actually make a difference to your pet?
The marketplace offers food formulas that are advertised as able to relieve stress in dogs and cats. These calming foods contain added L-tryptophan and/or alpha-casozepine as the purported effective substances. Products for dogs are sold in both pet shops and veterinary clinics. Therapeutic foods for cats with idiopathic cystitis may feature de-stressing as a co-treatment.
High tryptophan intake is thought to increase brain serotonin synthesis, resulting in a better mood in the animal. 4 studies have looked at the impact of supplemental L-tryptophan on the behaviour of dogs with different forms of anxiety. There is 1 published study on cats. Yet the overall outcome can be interpreted as a general lack of support for the effectiveness of additional L-tryptophan for canine and feline stress control.
Alpha-casozepine is a decapeptide derived from the tryptic hydrolysis of alpha-S1 casein from bovine milk. It binds to the GABAA receptor and may elicit an anxiolytic effect.
A double-blind study with an anxiolytic drug as a positive control claims that the drug and alpha-casozepine have an equal efficacy in dogs with anxiety-related disorders, but a placebo effect cannot be excluded. A test diet with casein hydrolysate changed various behaviours in dogs, involving both less and more anxiety. In a double-blind, placebo-controlled trial, alpha-casozepine treatment improved social phobias in cats, but the magnitude of the effect is considered insignificant and its reproducibility is unknown.
Therapeutic calming foods for dogs and cats have been put to the test. The foods involved contained added L-tryptophan and hydrolysed milk proteins as the source of alpha-casozepine. In a longitudinal study, a veterinary stress-management food was evaluated in dogs with anxiety-related behaviour problems. The blind-test owners reported an immaterial improvement of anxiety-related behaviour, though a time effect cannot be excluded. In cats, a calming food did not affect plasma cortisol as the index of acute stress or it was ineffective in a human-interaction test.
In a trial using cats with idiopathic cystitis, the intervention involved both a de-stressing food and environmental enrichment, whereas the design was open and non-controlled.
Available research data cannot endorse the efficacy of calming pet foods supplemented with L-tryptophan and/or alpha-casozepine. Irrespective of any of this, the foods do not address the root cause of anxiety. Perhaps behaviour modification and training would be successful.