Are pets [dogs, cats, birds, fish] Muktzah on Shabbos?
All living creatures, other than humans, are Muktzah on Shabbos and hence are forbidden to be moved [in their normal method]. This applies even if the animal is fit for entertaining children. It is forbidden to even pet the animal. In addition, independent of the Muktzah prohibition, it is forbidden to make use of animals on Shabbos, [even in an irregular method] such as to lean on it, play with it, and the like. If, however, one designates the animal/creature for a specific purpose, such as to have as a pet for the sake of pleasure in seeing and interacting with the animal, then some Poskim rule the pet [bird, fish, dog, cat, turtle, etc] is not Muktzah and may be moved on Shabbos. Other Poskim, however, rule that the animal remains Muktzah, and remains forbidden to be moved on Shabbos. Practically, one is to be stringent in this matter, and not move even a pet animal on Shabbos. Furthermore, even according to the lenient opinion who permits moving the pet on Shabbos, it remains forbidden to make a use of the pet on Shabbos, such as to ride on it, or cuddle with it for one’s benefit. Hence, one may not pet an animal on Shabbos.
To prevent Tzaar Baalei Chaim: The Sages allowed encouraging the movement of an animal in certain ways in order to prevent Tzaar Baalei Chaim. [Some Poskim rule that pets, which are under the dispute mentioned above, may be moved in any way in order to prevent Tzaar Baalei Chaim.] This matter will be discussed in greater length in a future lesson.
According to all, it is forbidden to make use of a living creature on Shabbos [leaning, riding, cuddling], including pets. However, to move a pet not for the sake of making a use of it, is disputed amongst Poskim if it is forbidden due to Muktzah. Practically, one is to be stringent not to move or even pet an animal on Shabbos.
 However, they may be moved with an irregularity, as is the law by all Muktzah. [Admur 308:15; 311:15; 276:9-10; 266:19; 301:39 KU”A 10; So also rules: Mishneh Shabbos 141a; Rosh 3:19 in name of Rabbeinu Yonah; Michaber 311:8; Michaber 308:43; Rama 308:3 regarding blowing; M”A 308:7 regarding kicking Muktzah and 308:41 regarding his question on Michaber regarding sitting on Mukztah; M”B 276:31; 308:13 and 81 and 88; 311:30; 1st opinion in Chayeh Adam; Derech Hachayim; 1st opinion in Aruch Hashulchan 311:20; Kaf Hachaim 311:68 [although brings strict opinion in 69].
 Admur 308:78; See also 308:8; Michaber 308:39; Shabbos 43a and 128a
The reason: As they have no use on Shabbos when they are alive. [Admur ibid; Levush 308:39; Maggid Mishneh 25:25]
 Admur 308:78; Tosafus Shabbos 45a
The reason: This can be understood in one of two ways: 1) It is Muktzah because it was not designated for this purpose before Shabbos, and hence is similar to deciding on Shabbos to use a stone for a certain purpose. Or 2) It is Muktzah because it usually has no use on Shabbos, and hence the Sages did not create any ability of designation from before Shabbos, similar to figs and raisins that are in the drying process, which can never be designated. [See Admur 310:2 and 9] The practical ramification of the two reasons is in a case that one did designate the animal before Shabbos, as will be explained.
 See Admur 308:78; Taz 308:23; M”A 308:68; M”B 308:151 that it is forbidden to move any part of Muktzah; Admur 305:23 “Even to rub a child on its back to entertain him is forbidden”; The following Poskim rule it is forbidden to move even the hair both due to Mukztah and due to the prohibition of making use of an animal on Shabbos: Tosefes Shabbos 302:34, brought in Biur Halacha 305:18 “Mikaneach”; Toras Shabbos 302:21; Shevisas Hashabbos Kotzer 137; Kaf Hachaim 302:89; Keren Ledavid 92; Piskeiy Teshuvos 305:5 footnote 34 and 308:54 footnote 446
Other opinions: Some Poskim question that perhaps it is permitted to move the hairs of an animal, and the Sages only forbade against moving their bodies. [Biur Halacha 305:18 “Mikaneach” based on Michaber 302:11 who permits cleaning mud off using the tail of a horse]
Ruling of Poskim permitting cleaning mud with the tail of an animal: The Poskim rule that it is permitted for one to use the tail of a horse or cow to clean mud off one’s hands. [Admur 302:22; Michaber 302:11; Rambam 22:19; Tosefta 17:5] This seems to imply that one may use and move the hairs of an animal on Shabbos, and the Sages did not decree against it. [Biur Halacha ibid] Other Poskim however suggest that this ruling refers to a detached tail from a horse and cow, or to a case of Geraf Shel Reiy, which permits moving Muktzah. However, in truth, it is forbidden to move the tail of an animal both due to Muktzah and due to the prohibition against making use of an animal. [Tosefes Shabbos 302; Toras Shabbos 302:21; Shevisas Hashabbos Kotzer 137; Kaf Hachaim 302:89; Keren Ledavid 92; Piskeiy Teshuvos 305 footnote 34]
 Admur 305:23; Michaber 305:18; Misneh Beitza 36b
 Halachos Ketanos 1:45, brought in in Minchas Shabbos 88:10; Nezer Yisrael 10:3 in Likkutei Rima 11 in name of Maharach Or Zarua 81 [Or Zarua later retracts his ruling in 82]; Tosafus Shabbos 45b in name of Rav Yosef [Tosafus ibid later rejects this approach]; Minchas Shabbos 88:10 in name of Pachad Yitzchak; Igros Moshe 5:22-21 [contradicts himself in 4:16]; See Betzel Hachochma 5:33-34; Az Nidbaru 8:36; 9:27
 The reason: As any Muktzah item which has been designated for a permitted use on Shabbos seizes to be Muktzah [see Admur 308:50-53] and there is no reason to not apply the same rule for animals, and hence if the animal has been designated for a permitted use, such as for a decorative purpose or for entertainment, then it is not considered Muktzah.
 Hagahos Rav Akiva Eiger 308:17; Tosafus Shabbos 45b “They are Muktzah like dates and figs” and dates and figs can never be designated; Rosh, brought in Or Zarua 82 “My Heart does not allow me to permit moving the chirping birds, as animals have a different law than vessels [Rules animals are Muktzah even if one was Miyached them, such as to serve as chirping birds]; Conclusion of Maharach Or Zarua 82 like the Rosh, as he was a known Posek; Conclusion of Minchas Shabbos 88:10; Orchos Chaim 308:24; Daas Torah 308; Kaf Hachaim 308:235; Igros Moshe 4:16 [contradicts himself in 5:22]; Yabia Omer 5:26; SSH”K 27 footnote 96 in name of Rav SZ”A; See Ketzos Hashulchan 121 footnote 4 regarding fish; See Betzeil Hachachmah 5:33;
Opinion of Admur: Admur 308:78 rules that one may not move a bird even to entertain a child. This ruling is based on Tosafus ibid who rules that animals are like figs and raisings in the drying process which are Muktzah even if designated. This would seem to imply that according to Admur one cannot designate animals for a use on Shabbos. Furthermore, from the fact Admur omits writing the ability of designating an animal, also seems to reveal his intent in the above words, that it comes to refer even to a case that the animal is designated. On the other hand, however, one can infer from the words “since they have no use on Shabbos” that if they are designated for a use, then they are not Muktzah. Furthermore, the words “even if they are fit to entertain a child” can be inferred that it refers to a case that they were not designated. Furthermore, the logic used by Admur 310:9 to explain why figs and raisins in the drying process always remain Muktzah does not fit with the case of animals, as figs and grapes in the drying process have absolutely no use and therefore cannot be designated for anything, while animals have the use of a pet. [See Az Nidbaru ibid who in truth learns this case is different, as the bird has been designated specifically for this purpose, while perhaps in the case of Admur it has not been designated, and hence according to all remains Mukztah.] Vetzaruch Iyun!
 The reason: As a) They are unable to be designated for a permitted use, just like dried figs and grapes may not be designated while in the drying process. [See Tosafus ibid; Rosh ibid] b) As it is forbidden to make use of an animal on Shabbos, and the Sages did not differentiate in their decree. [Rosh brought in Or Zarua ibid; See Admur 305:23]
 Minchas Shabbos 308:80; Az Nidbaru 8:36; 9:27; Beir Moshe 2:28; Yabia Omer 5:26; Piskeiy Teshuvos 305:5 and 308:54
 Minchas Shabbos 88:10 in name of Pachad Yitzchak; Az Nidbaru ibid
 See Admur 2305:23 and Poskim ibid that petting is included in the prohibition of making use of animals
 See 308:79; Michaber 308:40; Shabbos 128
 Betzeil Hachachma ibid; SSH”K 27:28; Yabia Omer ibid