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79:5. (25) Donkey excrement which is soft, when the donkey completes a trip [apparently its excrement is different when penned] and that of a cat, a marten [a kind of weasel --SP] and a rotting carcass are all treated for the purposes of the law as human excrement [and one may not read the Shema within 4 cubits of them, even if there is no smell emanating from the excrement --SP]. One who is walking along a road, even if he sees animal excrement in front of him [and he does not know whether it is from a donkey or some other animal --SP], if no smell reaches him then he does not have to worry about the minority, meaning to assume that it might come from a donkey. But near a city some say that one should worry [that it might be donkey excrement] since the majority of animals commonly found there are donkeys {Rema: [but this only applies] in a place where donkeys are common}.
MB 25: Donkey excrement - [The excrement of] all of these [animals] usually has a bad smell, and therefore even if one came across one that did not smell, it is still forbidden [to read the Shema within 4 cubits] because it is considered like human excrement - so wrote the Magen Avrohom, and see in the Biur Halacha [where the author of the Mishnah Berurah discusses whether this law applies only where the excrement is still soft and has not yet had a chance to harden. He leaves the matter (as far as the practical law is concerned) as requiring further investigation. --SP]
79:6. In the Jerusalem Talmud it prohibits reading [the Shema] in the presence of the urine of a donkey which has completed a trip, and [also] in the presence of excrement of chickens which is (26) red.
MB 26: red - From his [the Shulchan Aruch's] language it implies that what he means to say is that [red refers to the excrement,] and because it is red it has a great stench [ie. the word "red", which is in the singular in the Shulchan Aruch, refers to the excrement rather than the chickens --SP]. But the later Rabbis wrote that red chickens are what we call the "English Hen" [according to the new Blum printing, this is a Turkey - YM] whose exrement stinks a lot; it is preferable not to keep them in any house where one learns [Torah] or makes Blessings, especially a scholar's house, because it is impossible for him not to have Torah thoughts (from the book Minchas Shemu'el in Halacha Berurah).
79:7. The excrement of chickens (27) which go into the house has the same law as the excrement of an animal, but (28) their coop has a rotten stench and has the same law as human excrement.
Siman 79
. One who comes across excrement when reading the Shema (continued)