פירוש על עבודה זרה 44:13

According to this baraita, we need not be concerned lest the animal engaged in bestiality. This directly contradicts our mishnah.

According to this resolution, the non-Jew might engage in bestiality with animals he does not own. Thus Jews should not leave our animals with them. But they will not engage in bestiality with their own animals. Therefore, Jews can buy their animals.

Rav’s reasoning for why non-Jews will not engage in bestiality with their own animals applies only to female animals. So R. Kahana explains that it applies to male animals as well. Having sex with human beings will weaken them. Please—do not ask me if this is actually true. And probably not a good idea to google it either. Just go on to the next section.

We need not be concerned lest their shepherds have sex with the animals they are watching for non-Jews because the shepherd is afraid of losing his wages. In other words, even though the animal does not belong to him, he’ll still behave himself around it.

The problem with the above solution is that another baraita seems to imply the opposite—we are concerned lest non-Jewish shepherds engage in bestiality, and therefore Jews should not turn over animals to them.
The solution is that non-Jews know a lot about bestiality and would know when one shepherd is taking his animal aside for a little more than just grooming. Therefore, they will be afraid of losing their wages. But when it comes to working with Jews, Jews are not so familiar with bestiality, so they won’t know what the shepherd is doing. The non-Jew will not be afraid lest he gets caught.
Rabbah connects this to a folk saying, about how a spy (or perhaps gossip-monger/evil doer) knows what others plot.

It is permitted to buy male animals from female non-Jews. The woman will not want the animal to form this type of bond with her.

A widow should not take in young single men as lodgers because they may end up having sex with her and then covering it up out of modesty. However, if what we said above is true, that women won’t engage in bestiality because the animal will follow after her, then why should she not raise dogs? The answer is that she could throw them some meat and then everyone will think the dog follows after her because of the meat. [I know, this is a difficult sugya.]

We don’t leave female animals alone with them lest the paramour comes knocking, doesn’t find the wife and instead finds the animal.

I think we hear here a rabbinic ontological understanding of non-Jews, one that has echoes in many cultures trying to delineate and separate themselves from whomever they define as “the other.” Non-Jews are irreparably full of lust. This terrible pollution is their genetic heritage from the time of Eve, and was put into her by the snake [yes, I think this is a sexual allusion.] Thus all non-Jews are full of incontrollable lust. I should note that I am in the middle of reading a book by Stephen Greenblatt called “The Rise and Fall of Adam and Eve.” Christians throughout the medieval period identified the Jews with Eve, who was fallen, whereas the Christians were identified with Mary, mother of god, redeemed from original sin through Christ . Thus we see both religions using the figure of Eve in a misogynistic means of pointing out the pollution of the other—the Jews identify Eve with the non-Jews, and the Christians identify her with the Jews.

This seems to be some sort of acknowledgment that Jews and non-Jews all come from the same essential genes—from Eve. But the Sinai revelation, accepted only by the Jews, was a redeeming moment for the Jews and ended “their pollution.” In this context R. Yohanan’s means that Jews, having accepted the Torah at Sinai, no longer have the same lustful desires (here to have sex with animals) that non-Jews do. Of course there is no way of empirically testing such a statement. But it is nevertheless an interesting conception of Torah—Torah changes the essential inner being of a person. It is not just an overlay of laws meant to keep one in line. Rather, by accepting it, Jews changed the core of their identity and no longer have the same desires as do others.

Evidently, at least according to these rabbis, they do.