https://riseandshinerabbitry.com/2012/06/09/medicinal-herbs-for-rabbits/
They use “4 capsules” in a gallon of drinking water.
Oxbow Natural Science Immune support includes 9mg of goldenseal per hay tablet, and recommends 1/2 tab;et per day for bunnies 1/4 to 1lb, 1 tab let for 1-4lb, and 2 tablets for 4+lb.
I use their immune support tablets for my E.C. bunny. Sometimes I make the tablets myself, and I give him 36mg per day – of the echinacea/goldenseal capsules. My bunny weigs 4.4lb.
I haven’t found a dose for rabbits. Not even the human doses are standard. Medical forums have doses for immune support, cold attack, and all sorts of purposes. So honestly – I take the dose for immune support for humans, X-mg for a 180lb male, divide by 180, and multiply by my rabbit’s weight, to scale down the “regular” human dose, to the appropriate amount for my bunny’s weight.
This same bunny has weepy eyes. Copnstantly. I tried antibiotics, different hay, air cleaner,hepa filter, allergy medicine, and the est thing was his pal grooming his eye, and second best, me grooming his eye. The cozier they are, the more she grooms his face, the better his eyes loo. When she “slacks” in her groomng duties, his weepiness becomes evident. He has his teeth filed twice a year, so I honestly don’t know wha tcauses it. Just that grooming helps tremendousely.