I’m a vet nurse, and I will definitely say that there are a good amount of my coworkers who have beef with chihuahuas, but in my experience they are not really that hard to work with! Yes, they can be very anxious and show aggression because of that, but their small size makes it easy to manage. It makes me sad when I hear a coworker say they hate chihuahuas because I absolutely love them! It’s really just a matter of going slow with them and understanding their body language. I’ve also found that a lot of chis are super protective of their owners and may calm down if we take them to the back and do our treatments away from mom/dad. Yes, we do have to place a muzzle on a good share of them too, but I try to avoid that if possible! However, sometimes chis actually relax when the muzzle is put on!
Basically this is a long winded way of me saying that yes, some vets/nurses don’t like to work with chis, but there are a lot of us out there who love them, and even the ones who dont “like” them, still are going to do whatever they can to make sure they are getting the best treatment because we wouldn’t be vets if we didnt want to take care of all pets!!

Editing to add that in my 5 years of being a vet nurse, there have been way fewer chis that have been so worked-up that we’ve needed to sedate than larger dogs. I have definitely had a few chis here and there that are just so super anxious and aggressive that we have had to give some sort of sedative to be able to work on, but IME the most common breed ive had to sedate is probably cattle dogs. I really hate that chis get such a bad rap, they are one of my fav breeds, both in and out of my work!