Pliny the Elder [1st century CE] (Natural History, Book 8, 41; 10, 94): [Book 8, 41] Barbarian hunters catch leopards by means of meat rubbed over with wolf's-bane; their throats are at once attacked by violent pain (in consequence of which some people have given this poison a Greek name meaning choke-leopard), but to cure this the creature doses itself with human excrement, and in general it is so greedy for this that shepherds have a plan of hanging up some of it in a vessel too high for the leopard to be able to reach it by jumping up, and the animal keeps springing up and trying to get it till it is exhausted and finally dies, although otherwise its vitality is so persistent that it will go on fighting for a long time after its entrails have been torn out. [Book 10, 94] In Africa also leopards crouch in the thick foliage Feline of the trees and hidden by their boughs leap down on to animals passing by, and stalk their prey from the perches of birds. - [Rackham translation]

Saint Ambrose [4th century CE] (Hexameron, Book 6, 3.15; 6, 4.26; 6, 4.28): [Book 6, 3.15] Scripture is also not silent about the nature of the leopard. By the varied character of his coat he betrays the variety of his emotions. Jeremias says: 'If the Ethiopean can change his skin or the leopard his spots'. This is not said merely of what is external. It refers, also, to changes in the fierce nature of the animal. The Jewish people, whose characters were spoiled because of the gloomy and uneasy fluctuations of their hearts and minds, could not attain the grace of good purpose. Once they had acquired the fierce character of a wild beast, they were unable to return to a better and improved mode of life. [Book 6, 4.26] To a leopard the blood of a wild she-goat serves as an antidote against physical weakness. [Book 6, 4.28] Why do I need to mention the fact that men are fond of garlic and use as a food a substance which the leopard avoids? Hence, as soon as a person gets ready to prepare garlic, a leopard, who is unable to tolerate it, is apt to leap forth from that region. To think that you use for food and infuse into your vitals a substance whose very odor a ferocious wild beast cannot endure! - [Savage translation, 1961]

Isidore of Seville [7th century CE] (Etymologies, Book 12, 2:11): The leopard [leopardus] is born from the cross-mating of a lioness and a pard, and yields a third breed. So also Pliny in his Natural History [book 8, 42] says a lion mates with a female pard, or a male pard with a lioness, and from either union this mixed-breed offspring is created, just like a mule or hinny.

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Quadrupeds 4.55): They are sometimes tamed, but never so much as to forget their cruelty. They are, however, domesticated for hunting. Therefore, when they are led on a hunt, they seek for the prey. But if the leopard cannot catch it at the fourth or fifth leap, it stops, furiously angry. And unless the hunter immediately offers an animal to the furious beast, whose blood it is pleased with, it rushes at the hunter or at whoever it meets, because it is impossible to appease it except in blood. But in this they are provided for who wish to hunt with these beasts, because they always have lambs or other animals close at hand, with which they appease the angry leopard. - [Badke translation/paraphrase]

Bartholomaeus Anglicus [13th century CE] (Liber de proprietatibus rerum, Book18.66): Leopardus is a beast most cruell, and is gendered of a Perde and of a Lyonesse, as Isi[dore] saith li. 12. For as Plin[y] saieth, the Lion gendreth with the Perdus, or the Perde with the Lionnesse, and of such gendering commeth unkinde Perdes, as of an Horse and of a she Asse, or of a Mare and a male Asse is gendered & Mule. As Isi[dore] saith, the Leopardis a full réesing beast and head strong, and thirsteth bloud: and the female is more cruell than the male, as Arist[otle] saith, and hath divers colours, as the Parde hath, and pursueth his pray starting and leaping, and not running: and if he taketh not his praye in the third leape or in the fourth, then he stinteth for indignation, & goeth backward, as though he wer over come, and is lyke to a Lyon in bodye, tayle and féete, but in shape of the head, he is lyke to the Parde. And he is lesse in body than the Lyon, and therefore he dreadeth the Lyon, and maketh a cave under the earth with double entering, one by which he goeth in, and another, by which he goeth out: and that cave is full wide and large in either entring, & more narrow and straight in the middle, and so when the Lyon commeth, he flyeth and falleth sodainlye into the cave, and the Lyon pursueth him with a great réese, & entereth also into the cave, and thinketh there to have the masterie of the Leopard, but for greatnesse of his body, he may not passe fréely by the middle of the den, which is full straight: and when the Leopard knoweth that ye Lyon is so let and helde in ye straight place, he goeth out of the den forward, & commeth againe into the denne in the other side behinde the Lion, and réeseth on him behinde with biting and with clawes: and so the Leopard hath ofte in ye wise, the masterie of the Lyon by crafte, and not by strength, & so the lesse beast hath ofte the masterie of the strong beast, by deceipt and guyle in the denne, and dare not reese on him openly in the fielde, as Homer saith, in libro. De pugms & Astucijs bestiarum. Lib. 8. Arist[otle] speaketh of a beast that is called Ferculio, and Avicen[na] calleth that beast Leopardus. A beast sayth Ari[stotle] that is called Ferculio, eateth somtime venemous things, and lecketh then mans dirte, and eateth it: and therefore Hunters hangeth suche dirte in some vessell, on a trée, and when the Leoparde commeth to that Tree, and leapeth up to take the dirte, then the hunters slaye him in the meane time while he is thereabout: & the Panther doth the same, & the Perdus also, as it is sayd ther. Also Plinius speaketh of the Leopard and saith, that somtime the Leopard is sicke, and drinketh wilde Goates bloud, and scapeth from the sicknesse in that wise. - [Batman]