From Background to the Daf-
>>3)
[line 3]LIFNEI HA'KELEV- even if the dog does not belong to him, or is ownerless, it is a Mitzvah to feed it, since a dog is always hungry (MAGEN AVRAHAM OC 324:7)<<
Rashi disagrees with this. This entry should read-
3)[line 3]LIFNEI HA'KELEV- before a dog a) [that belongs to him and relies on him for its food (RASHI); b) [even if it does not belong to him, or is ownerless (since it is a Mitzvah to feed it, since a dog is always hungry) (MAGEN AVRAHAM OC 324:7)
Shalom R' Moshie,
Thank you for your careful observation.
I am not sure that Rashi necessarily disagrees with the Magen Avraham. Rashi writes only, "Rami Alei l'Zono," but he does not explicitly say that this refers only to one's own dog. Indeed, the Magen Avraham (OC 324:7) appears to understand that the Gemara refers even to a dog that does not belong to him.
This understanding is supported by the Meiri here, who explicitly writes that one may feed even a dog that is not his own, explaining that "Mezonosav Alecha" applies because of "la'Kelev Tashlichun Oso" or in reward for "Lo Yecheratz Kelev Leshono." The Aruch ha'Shulchan (OC 324:2) also defends this reading, noting that Rashi writes simply "Kelev Rami Alei l'Zono" rather than "Kelev she'Rami Alei," and concludes that one may feed even a dog that is not his own, at least on an occasional basis.
That said, your comment does point to something that could be clarified. The Background might better explain that the Magen Avraham extends the Gemara to dogs generally, rather than leaving the impression that this is the only possible reading of Rashi.
Kol Tuv,
Aharon Steiner