Shabbat 52 - April 27

Are animals allowed to carry items that are used for decorative purposes? The mishna discusses the purification of the implements worn on the animal but are they susceptible to impurities? Aren't only items used by humans susceptible to impurities? How can these items be purified by the animal while wearing it around one's neck? Isn't the animal considered a barrier for the water since the water can't fully surround the item? Rabbi Eliezer tells a student that all rings and all needles are the same when it comes to laws of impurity. The gemara questions this by bringing various sources that indicate otherwise.