Tea tree oil, also known as melaleuca oil, has increased in popularity with the heightened use of “natural remedies.” This ingredient can be found in gels, body lotions, shampoos, conditioners, balms, toothpaste, insect repellants, and other household products.

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In veterinary practice, tea tree oil has been marketed for use on dogs, cats, ferrets, and horses to treat external parasites. Though appropriate dilutions of tea tree oil can be used, it is extremely important to talk with your veterinarian prior to use. Due to intoxication, 100% tea tree oil should never be used on an animal.

Birds are also indicated for this toxicity.

Signs and symptoms of toxicity: extremely low body temperature, weakness, decreased heart rate, difficulty walking, tremors, and skin irritation. Clinical signs may be seen within 1-2 hours of application but may take up to 8 hours to appear.

Toxic consumption:
The minimum toxicity threshold is unknown. All incidences of exposure should be reported immediately. Dose ranges of 1.9-5 g/kg (0.8 – 2.2 g/lb) or 1.9-2.6 mL/kg (0.8 – 1.1 mL/lb) may be fatal.

Intoxication is most often seen when 100% tea tree oil is used. As little as 7-8 drops (10-20 mL) applied to the skin may be fatal to both cats and dogs. Products with low concentrations (e.g. shampoos, body washes) are generally not considered toxic.

Dogs: Tea Tree Oil Toxic/Lethal Consumption
X-Small
Yorkie, Chihuahua
Small
Pug, Boston Terrier, Poodle
Medium
Beagle, Scottish Terrier
Large
Boxer, Cocker Spaniel
X-Large
Retriever, German Shepherd
XX-Large
Great Dane, St. Bernard
1 – 10 lbs.
(0.45 – 4.6 kg)
11 – 25 lbs.
(5 – 11.4 kg)
26 – 40 lbs.
(11.8 – 18.2 kg)
41 – 70 lbs.
(18.6 – 31.8 kg)
71 – 90 lbs.
(32.3 – 40.9 kg)
91 – 110 lbs.
(41.4 – 50 kg)
dog1 dog2 dog3 dog4 dog7 dog6
> 0.8 g or mL > 9.4 g or mL > 22 g or mL > 35 g or mL > 61 g or mL > 78.5 g or mL

 

Cats: Tea Tree Oil Toxic/Lethal Consumption
Most Cats

Large Cats
1 – 10 lbs.
(0.45 – 4.6 kg)
11 – 25 lbs.
(5 – 11.4 kg)
cat1 fat cat
> 0.8 g or mL > 9.4 g or mL

 

References:
– Carson CF, Riley TV. Toxicity of the essential oil of Melaleuca alternifolia or tea tree oil. Clin Toxicol 1995; 33:193-194.
– Osweiler, G, et al. (2011). Blackwell’s five-minute veterinary consult clinical companion. Small Animal Toxicology. [Kindle version]. Retrieved from Amazon.com