Oils that may be toxic to your dog. Make sure you research thoroughly what would be safe then discuss with your veterinarian. Here are links to information regarding toxic oils:
https://allnaturalpetcare.com/blog/2018/02/27/common-diffuser-essential-oils-may-toxic-dogs-cats-birds-pets/
https://www.essentialoilhaven.com/essential-oils-for-dogs/
https://allnaturalpetcare.com/blog/2013/12/05/30-essential-oils-may-safe-pets/

Essential Oils Can Be Toxic:
Aromatherapy uses essential oils to create scents that we humans can enjoy. But it’s important to realize that many of these substances are volatile compounds, which means they can be potentially toxic to pets at certain concentrations. Cats can be especially sensitive to essential oils. Keep in mind that what is safe for you to use isn’t necessarily safe to use on or near your pet. Your pet can inadvertently inhale, lick or eat these essential oils, and the oils can even be absorbed through your pet’s skin. Your pet reacts differently to these substances than you do, so it’s important that you talk to your veterinarian before using them around your furry family members.

Aromatherapy – If you’re like many ME dog owners and have an anxious dog on your hands, then you may want to give dog aromatherapy a try! Dog aromatherapy is not something new. It’s been around for a long time.
https://dogs.thefuntimesguide.com/dog_aromatherapy/
https://naturallivingfamily.com/essential-oils-for-dogs/

Essential Oils That Are Best For Dogs:
If you’re interested in trying dog aromatherapy, here are 5 popular essential oils that can safely be used with dogs:
1.  Lavender – used for calming and soothing plus relieves itching
2.  Peppermint – insect repellent, promotes circulation, reduces allergies
3.  Niaouli – powerful healing agent that is not likely to irritate the skin
4.  German Chamomile – good for burns, stings and allergic reactions
5.  Helichrysum – has great anti-inflammatory properties

It can ease pain from cancer, stop diarrhea, and end nausea, among other things. One good reason to try aromatherapy with your dog is if he is afraid of loud noises (like from fireworks or thunderstorms). The calming effects from certain essential oils can help to relieve your dog’s stress and anxiety during those times.

Other times, it’s simply the aroma itself from the essential oils in the air or on dog toys that has the most powerful effect.

Before applying pure essential oil to your dog’s (or your own) skin, always check first to make sure the one you’re using is safe to use directly on skin. Often, essential oils need to be combined with a “carrier oil” first before applying to the skin. You can buy essential oils yourself and try mixing different ones together to create unique scents, or you can find dog aromatherapy sprays that are already pre-mixed to work best during different situations.can ease pain from cancer, stop diarrhea, and end nausea, among other things. One good reason to try aromatherapy with your dog is if he is afraid of loud noises (like from fireworks or thunderstorms). The calming effects from certain essential oils can help to relieve your dog’s stress and anxiety during those times.