i would never give my cats ivermectin. I usually rinse the tubes in the water troughs. I have a mixture of dogs. hounds, shepards, heelers and have not had a problem. The heeler had demotic mange and he was given liquid ivermectin and was on it a long time, Vet rx. it was dosed to his weight , and we were warned about the hazard. It was heal him up or put him down.
I have a few horses if you try to cover their head, there is a battle, and it can escalate into a dangerous situation quickly. So if any one tries this , be very careful.
I have 2 horses that will grab the syringe and suck on it. I had one horse, that if rushed turned his head sideways ,, the worse he acted. I had to hold the syringe and he would flip his head for 10 minutes or so, then I would touch the syringe to the halter, and we would go through the head flip routine, and then he would accept the syringe. To rush him was a full out fight,, rearing striking, flipping over .He was older, was losing sight, and had at one point had a mouth injury, which required 100 stitches , so he had scarring in his mouth . A dog had bit him (not my dog)
You could not see the scars, but you could feel them in his lips, when he was sedated for floating i would check to see if they were reducing.