If your pet doesn't tolerate New Year's Eve well, it would be best to take it to a quieter place. If you have a cottage, preferably somewhere secluded, it's best to celebrate there. If you have a cat, you have to consider whether it knows the environment well and how it tolerates travel.
But if you have to stay in the city, don't fret. You can still help your pet. Walk your dog during the daytime, before the fireworks start, and don't let it off the leash. It would be best to put a harness on, or at least to check and tighten the collar so that your dog can't slip out.
At home, try to find the quietest place in the house, like the bathroom or hallway. Move your pet's favorite bed there. It's best to find them a place to hide - like a box or a pet cave, a kennel covered with a blanket, etc.
Close the curtains before midnight and turn up the volume on the TV so that the bangs and flashes are less intense. And, most importantly, stay calm yourself so your pets feel there is nothing to fear. It's best not to comfort your dog, as that would just confirm that they should panic. It may sound insensitive, but if they try to climb onto your lap or start freaking out, it's best if you send them back to their place. This will show them that the situation is no different from any other day and that there is no reason to behave differently than usual. Sometimes the presence of another dog that is used to New Year's Eve celebrations and does not get excited can help. When your dog sees how calm he is, he'll know there's nothing wrong.
The Half Wrap method can also help dogs. This consists of tying a piece of fabric around the dog. The fabric should be at least 5 cm wide and stretchy. This wrap affects the dog's nervous system, making it calmer and feeling more secure. It's not hard to tie, all you need is a sufficiently long scarf. You can find lots of tutorials on the Internet if you enter the name of the method into the search engine.
Soothing medication should be used as a last resort, such as after the previous year's experience when the animal had a really hard time or received a new bad experience. Always consult your veterinarian about their suitability and dosage.
An alternative may be to use bach flower remedies, a soothing diffuser releasing pheromones, or other natural products. Avoid essential oils, however, especially for cats, as they do not have the enzymes required to break them down and they are therefore toxic to cats.
I hope that you enjoy New Year's celebrations with your pets as peacefully as possible.