Ebay seems to have delisted any horse deworming product with ivermectin. There were many listings a few days ago but they have been removed. Seems questionable.
You may have a valid point.
Scientists Once Thought Personality Was Set in Stone. They Were Wrong
https://www.discovermagazine.com/mind/scientists-once-thought-personality-was-set-in-stone-they-were-wrong
The rats had previously been infected with Toxoplasma gondii, a brain parasite that, as the scientists running the trials were learning, considerably altered the way the rats behaved. Not only did they display this potentially fatal, certainly ill-advised feline attraction, but they were also more eager to explore the maze than uninfected animals were. For better or for worse, their rat “personality” had changed towards a higher level of openness to experience.
Humans are no rodents, but research indicates that T. gondii infection can affect our personalities, too. Studies show that infected people are less conscientious and more extroverted than those who are T. gondii-free. What’s more, at least 40 studies have by now linked toxoplasmosis with schizophrenia. “Almost everything we’ve seen in rats [has been] seen in people too, right down to this bizarre attraction to the smell of cat urine,” says pathobiologist Webster, one of the authors of the study on the infected rats.
T. gondii is a tiny parasite that you can pick up from eating undercooked meat or by changing a cat’s litter box. These single-celled organisms impact behavior because they’re “trying to maximize transmission from an intermediate host — such as a rodent — to its definitive host, which is the feline,” Webster says. Experiments on rodents suggest that cysts of the parasite present in the brain can alter levels of dopamine, a neurotransmitter that plays a role in reward and motivation. When a rodent is more motivated to explore and more attracted to cat urine, it’s more likely to be gobbled up by a cat, thereby spreading the parasite. Webster believes that T. gondii’s impacts on humans are just a “knock-on effect” that wasn’t intended for our species. Yet the parasite doesn’t know what host species it’s in, and will influence the behavior of rodents and humans alike.