Tea tree oil kicks some serious butt when it comes to many human skin conditions, thanks to its antimicrobial properties. Despite the essential oil's holistic healing benefits, it's toxic to canines.
Here's the problem with tea tree oil: It's highly toxic when ingested, causing symptoms such as a drunken gait, weakness, lethargy, tremors and possibly resulting in death. Even if you were to apply the oil to somewhere your pup can't lick, such as his ears or shoulders, VCA Animal Hospitals notes the oil is so toxic it must be diluted into 1 part oil and 250 parts water.
If you have a reason to apply tea tree oil to your pooch, then you probably have a reason to call your vet. The doc should always have a look at any type of skin condition that would warrant tea tree oil, from a fungal infection to what looks like dry skin. Certain medications or lifestyle changes may be needed rather than diluted tea tree oil. Even if you'd like to use it as an ear wash, contact your vet first.