Milk Thistle for Liver Ailments

I am a technician at an animal hospital in Illinois. We have been using milk thistle for about 2 years for some of our patients with elevated AlTs. Appears to help in many cases. We have been dosing only on my knowledge (a natural remedy enthusiast and herbal hobbyist) and a Herbal PDR we have. In severe cases using about 15 mg per kilogram per day. I would like to know if you have guidelines to offer. This would apply to cats and dogs mainly. We have been winging it and I'd love to have something more standard.

How wonderful to hear that herbs are being used in conventional veterinary applications.
There is little literature that specifies exact dosing for animals so I will give you the range of information I have. The following of course depends on whether you are using the normal herb or standardised extracts; I do not employ the latter, so do not have information regarding their use. Tinctures listed below would also have to have the alcohol portion removed before ingesting.
Powder:
Cats: 100 mg two to three times a day; 1/8 - 1/4 teaspoon two to three times a day
Dogs (25 lb): 100 - 150 mg two to three times a day; 1/2 teaspoon two to three times a day
Dogs (over 50 lb): 2/3 - 3/4 teaspoon two to three times a day
Tincture:
Cats: 5 - 10 drops two to three times a day; 10 drops two to three times a day
Dogs (25 lb): 5 - 10 drops two to three times a day; Up to 20 drops two to three times a day
Dogs (over 50 lb): 25 drops two to three times a day