--- title: "St John's Wort for Dogs | Petz Park" description: "St John's Wort (Hypericum perforatum) — active ingredient in Petz Park supplements. St John's Wort (Hypericum perforatum) in Petz Park supplements. 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[Home](/) 3. [Ingredients](/ingredients) 5. St John's Wort (Hypericum perforatum) # St John's Wort (Hypericum perforatum) St John's Wort (Hypericum perforatum) is a flowering plant native to Europe and Western Asia with one of the most extensive human research profiles of any herbal medicine. It is used in the Petz Park Stress and Anxiety for Dogs formula for its documented effects on mood and anxiety neurotransmitter systems. It is not present in the cat formula. ## Mechanism of Action The primary active constituent is hyperforin, which inhibits the neuronal reuptake of serotonin, dopamine, norepinephrine, GABA and glutamate simultaneously. This multi-neurotransmitter reuptake inhibition distinguishes St John's Wort mechanistically from selective serotonin reuptake inhibitors (SSRIs), which act on one pathway only. By reducing reuptake across multiple pathways, hyperforin supports broader neurotransmitter balance rather than amplifying a single signal. Thiamine (Vitamin B1) is included alongside it in the Petz Park formula at 130mg per scoop, supporting the nervous system's glucose metabolism and further contributing to a calm neurological state. ## Evidence Summary The human evidence base is the most substantial of any herbal calming agent. A Cochrane systematic review by Linde et al covering 29 randomised trials found St John's Wort extract significantly superior to placebo for mild to moderate depression, with comparable efficacy to standard antidepressants and fewer side effects. Veterinary-specific evidence is limited. Its inclusion in the Petz Park dog formula is justified by the established multi-neurotransmitter mechanism, the shared mammalian serotonergic and dopaminergic physiology between humans and dogs, and its strong safety profile at supplemental doses. Petz Park uses it as one component within a multi-ingredient formula designed to work through several calming pathways simultaneously. ## In Petz Park Products Stress and Anxiety for Dogs: St John's Wort 180mg per scoop. Not present in Stress and Anxiety for Cats. ## Safety and Considerations St John's Wort has clinically significant drug interactions in humans mediated through CYP450 enzyme induction, which can reduce plasma levels of medications including ciclosporin, digoxin and some antiretrovirals. The clinical significance of this mechanism at supplemental doses in dogs is not well established but the interaction risk is real. Dogs on prescription medications should not use Stress and Anxiety for Dogs without veterinary guidance. Not suitable for pregnant animals. Not present in the cat formula. ## Used in These Products Dog Products - [Stress and Anxiety for Dogs](/dogs/products/stress-anxiety-for-dogs) ## Helps With These Concerns Dog Health - [Anxiety and Stress in Dogs](/dogs/anxiety) [Back to Ingredients](/ingredients) Explore the Knowledge Centre - [All Ingredients](/ingredients) - [Dog Supplements](/dogs) - [Cat Supplements](/cats) - [Knowledge Centre Home](/) ![Petz Park](/images/petz-park-logo.png) Australian-made pet supplements for dogs and cats. ### Explore - [Home](/) - [Dogs](/dogs) - [Cats](/cats) - [Products](/products) - [Ingredients](/ingredients) - [Comparisons](/comparisons) - [FAQs](/faqs) - [About](/about) - [Trust & Proof](/trust) ### Dog Health - [Joint Health for Dogs](/dogs/joint-health) - [General Health and Vitality for Dogs](/dogs/general-health-vitality) - [Urinary and Kidney Health in Dogs](/dogs/urinary-kidney-health) - [Probiotics for Dogs](/dogs/probiotics) - [Liver Health for Dogs](/dogs/liver-health) - [Skin, Coat and Allergies in Dogs](/dogs/skin-coat-allergies) - [Brain and Cognitive Health in Dogs](/dogs/brain-cognitive-health) - [Anxiety and Stress in Dogs](/dogs/anxiety) - [Eye Health for Dogs](/dogs/eye-health) - [Dental Health for Dogs](/dogs/dental-health) - [Senior Dog Health](/dogs/senior-dog-health) - [Immune and Seasonal Health for Dogs](/dogs/immune-seasonal-health) ### Cat Health - [Joint Health for Cats](/cats/joint-health) - [Anxiety and Stress in Cats](/cats/anxiety) - [Dental Health for Cats](/cats/dental-health) - [Liver Health for Cats](/cats/liver-health) - [Skin, Coat and Allergies in Cats](/cats/skin-coat-allergies) - [General Health and Vitality for Cats](/cats/general-health-vitality) - [Urinary and Kidney Health in Cats](/cats/urinary-kidney-health) - [Eye Health for Cats](/cats/eye-health) - [Probiotics for Cats](/cats/probiotics) ### Contact - [petzpark.com.au](https://petzpark.com.au/?utm_source=knowledgecentre&utm_medium=ingredient_article&utm_campaign=st_johns_wort&utm_content=navigation) [Instagram](https://www.instagram.com/petzpark "Instagram")[Facebook](https://www.facebook.com/petzpark "Facebook")[TikTok](https://www.tiktok.com/@petzpark "TikTok") © 2026 Petz Park. 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