Nettle in animals: allergy and joints

What is nettle?

Nettle (Urtica dioica) is a native herb whose stinging hairs release histamine, serotonin and acetylcholine upon contact. These substances cause the burning pain and swelling that gave the plant its name. Dried or cooked nettle loses this irritating effect completely and contains flavonoids, phytosterols and polyphenols with possible anti-inflammatory activity. The plant is also nutritionally valuable: it is rich in iron, calcium, magnesium and vitamin C.

Claims versus evidence

Nettle is traditionally used for joint complaints and allergic reactions, also in animals. What does the research say?

Pain and anti-inflammatory effects

In mouse and rat studies, nettle extract reduced the pain response by 41–81% and reduced oedema by 26% at high doses [1]. The results are consistent within rodent models, but direct translation to dogs or horses is not substantiated.

Allergy and respiratory tract

In a rat study using an asthma model, nettle extract reduced eosinophilia in bronchial lavage fluid by 60% and lipid peroxidation in lung tissue by 49% [2]. This indicates an antihistamine-like mechanism — an indication, not proof for clinical use in allergic dogs or horses.

Lack of clinical evidence

No clinical studies in dogs or horses have been found investigating the effect of nettle on allergy or joint complaints. Use in these species is based entirely on extrapolation from rodent models and traditional medicine.

Safety: fresh versus processed plant

This distinction is critical and must not be underestimated.

The Pet Poison Helpline classifies the fresh plant as dangerous for both dogs and horses [4]. Following contact with fresh nettle, neurological signs have been documented in dogs, including stumbling and muscle twitching [3]. In horses, fresh contact can cause hives (urticaria). For therapeutic or nutritional use: only use dried, cooked or otherwise processed nettle.

For which complaints is it used?

Nettle is considered for:

• Joint complaints (osteoarthritis, stiffness) — weak indirect evidence via rodent models [1]
• Seasonal or food allergies — indications from animal models, not clinically confirmed [2]
• Nutritional support — dried plant provides relevant minerals and vitamins

For none of these indications is direct clinical evidence in dogs or horses available. Nettle is not recommended as a first choice; consultation with a (holistic) veterinary surgeon is always advisable.

Dosage

Dosage for therapeutic use must only be determined under the supervision of a veterinary surgeon. A scientifically substantiated therapeutic dose for dogs or horses does not currently exist.