https://www.tractorsupply.com/tsc/product/durvet-ivermectin-paste-187-608-g
The plunger is graduated in fifty-pound increments.

There’s a tractor supply right near me.
Thanks for the tip.
Yes, my tractor supply said the reason they keep this cheap stuff locked up is because it is high theft due to people using it on dogs.
The taste issue with the horse ivermectin can be overcome by putting the appropriate dose into an empty gelatin capsule.
Just an ordinary one — the vegetarian or vegan ones have some time-delay effect.
Size 0 or 00 will work. You do not have to fill it completely, and taking two partially filled capsules is also a possibility.
A small scale from Harbor Freight may help with dosing. About $12.