Herbal Medicine in Pets: Balancing Natural Support with Veterinary Safety

Figure 1: Herbal medicine set up

Interest in herbal and natural remedies for companion animals has grown substantially over the past three decades, with owner-reported use of complementary and alternative approaches rising from roughly one-third to over two-fifths of surveyed pet owners between 1990 and 1997 (dvm360, 2009). At The Andys Veterinary Clinic, we welcome this interest and are frequently asked whether herbal remedies are safe or beneficial for pets. It is a valid and important question, and one that deserves a considered, evidence-based answer rather than a simple yes or no.

Does “Natural” Always Mean “Safe”?

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A central point we ask every client to understand is that a compound's natural origin has no bearing on its physiological safety in a given species. Many herbs and plant-derived substances that are well tolerated by humans are toxic to dogs and cats, and the underlying mechanisms are well characterised in the veterinary literature.

Figure 2: Garlic and onion

Garlic and onion are a well-documented example. Both belong to the genus Allium, which contains organosulfur compounds — including thiosulfates and diallyl derivatives — that cause oxidative damage to red blood cell membranes and haemoglobin (Gwaltney-Brant, 2024). This oxidative injury leads to the formation of Heinz bodies within erythrocytes, which become fragile and are prematurely removed from circulation, resulting in haemolytic anaemia. An in vitro study using canine blood samples confirmed that all tested forms of garlic caused measurable red cell damage, with dried and granulated preparations producing significantly greater hemolysis than fresh garlic (Beleć et al., 2025). Clinical signs typically become apparent within 24 hours of ingestion and can persist for several days.

Figure 3. Simplified pathway of Allium (garlic/onion) toxicosis in dogs and cats, based on the mechanism described by Gwaltney-Brant (2024) and confirmed experimentally by Beleć et al. (2025).

Figure 4: Essential oils: Cannabinoid oil (CBD oil)

Essential oils present a comparable risk profile. Tea tree oil (Melaleuca alternifolia) is the most frequently reported essential oil intoxicant in companion animals, with a retrospective review of 443 cases in dogs and cats documenting signs ranging from ataxia and weakness to central nervous system depression and coma following topical exposure (Khan et al., 2014).

Cats are disproportionately affected because they lack sufficient hepatic glucuronyl transferase, an enzyme required to metabolise many of the terpene compounds found in essential oils, leaving them markedly more vulnerable to toxicosis than dogs even at comparable exposure levels (Merck Veterinary Manual, 2025).

Species is only one variable. Appropriate dosing is also governed by breed, body weight, age, and existing health conditions, none of which can be reliably extrapolated from a human or generic “natural product” dosing guideline. A remedy dosed safely for a healthy adult Labrador may carry an entirely different risk profile in a geriatric cat with reduced hepatic or renal function.

Interactions with Medication and Anaesthesia

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Figure 5: Best herbs for the immune system in humans

Beyond direct toxicity, herbal supplements can pharmacologically interact with prescribed medication. Reviews of herb–surgery interactions note that several commonly used botanicals affect arachidonic acid metabolism and platelet aggregation, which can compound the bleeding risk already associated with non-steroidal anti-inflammatory drugs and other perioperative medications (Robinson, 2009). Herbal compounds may also alter hepatic drug metabolism, which becomes clinically significant under anaesthesia, when reduced cardiac output and hepatic blood flow already slow the clearance of anaesthetic agents.

This is why we ask every client to disclose any herbal or supplement use before a procedure, before anaesthesia, or when starting a new treatment — not as a formality, but because it materially changes our assessment of risk.

Figure 6. Safety comparison of 21 herbs commonly promoted for immune support in humans, cross-referenced against veterinary toxicology sources.

The Role of the Veterinary Team in Herbal Medicine

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Veterinary policy on complementary, alternative, and integrative veterinary medicine holds that all treatment modalities, herbal or otherwise, should be held to the same evidentiary and ethical standard: diagnosis and treatment grounded in sound veterinary principles, delivered within a valid veterinarian–client–patient relationship, with documented owner consent (AVMA, 2025). In practice, this means herbal medicine, where appropriate, functions as a complement to an established diagnosis and treatment plan rather than a substitute for one.

Figure 7. Three principal risk categories associated with unsupervised herbal use in companion animals, synthesised from AVMA (2025), Khan et al. (2014), and Robinson (2009).

Why Veterinary Guidance Matters

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Pets cannot report internal symptoms, and by the time visible signs of illness appear, complications from an unsafe remedy or a masked underlying condition may already be well established. Responsible, veterinarian-guided use of herbal medicine can improve quality of life for many pets, particularly as a complement to conventional treatment for conditions such as chronic pain or mild gastrointestinal upset. Used without guidance, however, the same substances carry a genuine risk of harm.

At The Andys Veterinary Clinic, our goal is to support your pet's wellbeing through individualised, evidence-based care. If you are considering introducing herbal or natural remedies into your pet's health plan, we encourage you to consult with us first or your veterinarian so that we can assess your pet's specific needs and help you make an informed, safe decision.

References

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1. American Society for the Prevention of Cruelty to Animals. (2025, October 7). Are these fall plants hazardous or harmless? ASPCA. aspca.org

2. American Society for the Prevention of Cruelty to Animals. (n.d.). Toxic and non-toxic plants: Lemon grass. ASPCA. Retrieved August 9, 2026, from aspca.org

3. American Veterinary Medical Association. (2025). Complementary, alternative, and integrative veterinary medicine [Policy statement]. avma.org

4. Beleć, K., Barć, J., & Lasek, O. (2025). The effect of the type and concentration of garlic (Allium sativum) on Heinz body concentrations in canine erythrocytes—An in vitro study. Animals, 15(21), Article 3188. https://doi.org/10.3390/ani15213188

5. dvm360. (2009, April 1). Complementary and alternative medicine [Proceedings]. dvm360.com

6. Gwaltney-Brant, S. M. (2024, September 11). Garlic and onion (Allium spp) toxicosis in animals. In Merck Veterinary Manual. merckvetmanual.com

7. Khan, S. A., McLean, M. K., & Slater, M. R. (2014). Concentrated tea tree oil toxicosis in dogs and cats: 443 cases (2002–2012). Journal of the American Veterinary Medical Association, 244(1), 95–99.

8. Merck Veterinary Manual. (2025, March 10). Toxicoses from essential oils in animals. merckvetmanual.com

9. Pet Poison Helpline. (2026, May 29). Elderberry is toxic to cats. petpoisonhelpline.com

10. Robinson, N. G. (2009). When herbs and surgery don't mix. Veterinary Practice News. veterinarypracticenews.com