My 185 lb miniature horse just did a 5 day horse paste trial. One click a day for 5 days. (Not one click but one 250lb mark)
It was feeling fine before I started the trial, just wanted to see what effect if any.
I can attest that my horse had no adverse reactions and appears to feel no difference from day one to day 5.
Different brands may be different. I’m in EU - one concentration of it here has three small notches per 100kg in a 700kg tube. Higher concentrations are available here by this one looked easier for small/pony size doses.