The Essential Oil Question Almost No One Asks

In over twenty years of teaching animal aromatherapy, I've noticed something curious: almost no one asks which rosemary, or cedarwood, they should use for their animal companion. Most pet parents don't even know there is more than one.

One of my students in the Animal Aromatherapy course at Essence of Thyme College of Holistic Studies recently ran into this exact gap, needing some guidance to understand why choose one  rosemary essential oil instead of another, despite sharing a botanical name.

The difference comes down to two concepts pet parents rarely hear about: chemotypes and species. Understanding both is a simple way to keep your animal friend safe while choosing essential oils that truly support them, rather than overwhelm them.

What Is a Chemotype?

A chemotype (abbreviated "CT") is a chemical variation within the same plant species. The plant looks the same, grows the same, and carries the same botanical name, but depending on climate, soil, and growing conditions, it produces a different dominant chemical makeup, and therefore a different essential oil.

Most essential oils don't have chemotypes, but when a chemotype does exist, you should see it noted in the oil's name, with "CT" followed by the dominant chemical constituent.

Here are four common essential oils with chemotype variations that pet parents should know:

• Lemongrass CT Rhodinol (Cymbopogon citratus)
• Rosemary CT 1,8-Cineole (Salvia rosmarinus)
• Rosemary CT Verbenone (Salvia rosmarinus)
• Thyme CT Linalool (Thymus vulgaris)

Here's why it matters... Rosemary ct 1,8-cineole shines for respiratory support, but it's a strong, stimulating oil that's too much for many animals.  Rosemary ct verbenone is gentler and a safer choice for our furry family.

For example, when supporting a dog with kennel cough, it's wise to start with rosemary ct verbenone and only move to rosemary ct 1,8-cineole if more respiratory support is needed. Or better yet, let the dog choose by offering both oils so they can self-select. Animals often have a clear preference, and that instinct is worth trusting.

What's the Difference Between a Chemotype and a Different Species?

A chemotype is a variation within a single species. Whereas chemotypes share the same genus and species, different species do not.

Here's where it gets a little more interesting, and honestly, a little more important to understand.

A common name may be used for several completely different species, each with its own unique Latin binomial (that italicized scientific name you'll sometimes see in parentheses). These are not variations of one plant. 

Cedarwood is a perfect example. When someone says "cedarwood essential oil," they could be talking about any of these:

• Atlas Cedarwood (Cedrus atlantica)
• Indian/Himalayan Cedarwood (Cedrus deodara)
• Virginian Cedarwood (Juniperus virginiana)

The differences aren't just a name, it shows up in how you'd use these oils. The Cedrus genus (Atlas and Himalayan cedarwood) tends to be more calming and grounding, a nice choice for an anxious dog or a cat who startles easily. (It's worth knowing that Atlas Cedarwood has been overharvested to the point of being considered at risk, so I lean toward Himalayan cedarwood or turn to a responsibly sourced supplier to purchase Atlas cedarwood.)

The Juniperus genus (Virginian Cedarwood) is the cedarwood essential oil to reach for to help repel insects. Even the scent tells the story: Atlas and Himalayan Cedarwood share a similar soft, woody-sweet aroma, while Virginian Cedarwood carries that classic, sharper cedar-wood scent most people think of when they hear "cedar." Remember that old cedar chest? Cedarwood kept the bugs away. 

Cedarwood... same common name, but three different plants, with different aromas, and different roles in your natural remedy toolkit.

Notice that these aren't even in the same genus. Did you notice two different plant genus (Cedrus and Juniperus) sharing one common name (cedarwood). That's a very different from a chemotype, and it's exactly why relying on a common name alone can lead you astray.

The gap can run even deeper than genus. Cedrus belongs to the pine family (Pinaceae), while Juniperus belongs to the cypress family (Cupressaceae), two entirely different plant families. So "cedarwood" on a label can mean plants that aren't just different species, but different genus, in different families altogether.

If you'd like practical insights on choosing between cedarwood oils, I walk through it in this video: Which Cedarwood Essential Oil Should You Choose?

Ready to go one step further? Hang in there, this is good to know. 

Juniper Berry (Juniperus communis) shares the same genus (Juniperus) as Virginian Cedarwood, yet it's a completely different essential oil, in both chemistry and in how it's made. Cedarwood oils, Virginian Cedarwood included, are steam distilled from the wood or sawdust shavings. However as the name describes, Juniper Berry essential oil comes from distilling the berries. Same genus, different plant part, different process, resulting in a very different oil.  Both are safe for animals, when used appropriately, but have different reasons to reach for them. 

As you can see, there's far more behind that name on the bottle than most of us were ever taught.

Why This Matters for Our Animal Companions

Animals have a heightened sense of smell, plus their body size, age, sensitivity, all of it, factor into what essential oil is appropriate for them. It's the difference between choosing essential oils that truly support them, rather than running away.

When you know to read the label and look for the Latin binomial, you're equipped to make a more informed, and gentler choices for your animal friend. It's a small habit that makes a real difference.

Frequently Asked Questions

Do all essential oils have chemotypes? No. Chemotypes are the exception, not the rule. Most essential oils don't have chemical variations within the same species. When they do exist, they're typically labeled with "CT" plus the dominant constituent.

How can I tell if an oil I already own has a chemotype? Check the label for "CT" followed by a chemical name (like "CT verbenone"). If it's not there, the oil likely doesn't have a documented chemotype, though it's always worth confirming the specific species with the supplier.

Is a milder chemotype always safer for my pet? Milder generally means gentler on the body, which is often a good starting point for animals, especially those who are elderly, sensitive, or new to essential oils. That said, "gentler" isn't the same as "risk-free." Proper dilution and species-appropriate use still matter.

Why do different species share the same common name? Common names were created for convenience, long before modern botanical classification. Many were named based on similar scent, appearance, or regional use, even when the plants aren't closely related botanically.

Understanding chemotypes and species won't just make you a savvier essential oil shopper. It will help you become a more confident, informed advocate for your animal companion's wellbeing, one gentle, educated choice at a time.