Tea tree oil can be toxic to cats, especially if the oil is applied without first being diluted, or if the dose is too high. Although products containing low concentrations of tea tree oil are not expected to be a problem in pets, the use of pure tea tree oil directly on the skin is potentially very serious in pets and should never be used. Exposure may cause ataxia, salivation, lethargy, coma, tremor, hypothermia, dermatitis, pruritus, or rash. Dermal exposure to tea tree oil may also result in dermatitis as the oil is irritant to skin. Tea tree oil is an active ingredient in numerous products such as facial washes, spot treatments, hand wash, hair care products, shower gels for humans, shampoos, skin creams, lotions, balms, insect repellents, and ear cleaners for pets.

In summary, tea tree oil is not safe for cats, and products containing low concentrations of tea tree oil are generally considered non-toxic for pets. If you want to use tea tree oil on or around your pets, its best to consult with your veterinarian before using any essential oils.