In the late 1800s, the Parke-Davis pharmaceutical company was basically the biggest weed dealer in America.
They promoted their cannabis medicines across the continent, proudly advertising that they rejected literal tons of shwaggy weed each year and used only the dankest primo nugs for their pot products
Cannabis’ active ingredients were not fully understood at this time. THC and other cannabinoids had not yet been isolated, so there was no way to chemically test extracts for their potency.
This made dosages for cannabis medicines very difficult to standardize. Parke-Davis would have some doctors complaining that their extracts weren’t doing anything, while others had patients taking hallucinatory voyages while trying to treat their arthritis pain.
Parke-Davis tried to solve this problem by launching their dog testing program in 1898. This is the “physiological test” referred to in their ad above. Over the next four decades, thousands of dogs were fed cannabis extracts and examined until they passed out.
I don’t know why Parke-Davis had to use dogs when I’m sure there would have been plenty of humans willing to consensually nom down cannabis treats all day and then report back on the results. An article from 1899 called “Trying it on the dog”