The Weekly Shtikle is dedicated le'iluy nishmas my dear Zadie and Bubbie, HaRav Chaim Yaakov ben Yitzchak and Yehudis bas Reuven Pinchas.
Rashi on 24:10 comments that Avraham's camels were discernable for they would go out muzzled so as to prevent them from eating from fields that did not belong to him. The Ramban (pasuk 34) asks on this based on the Midrash that refers to the donkey of R' Pinchas ben Yair about which it is said that even the animals of tzadikim, HaShem does not bring about bad through them and the donkey would not even eat "tevel". (Chullin 5b) If so, how could it be that Avraham had to be worried about his animals stealing to the point where he had to muzzle them? Should this same zchus not have been present in the house of Avraham Avinu?
There are a number of answers given. R' Ovadia miBartenura answers that perhaps the donkey of R' Pinchas ben Yair was different because it was the donkey he used personally for travel and there was a stronger bond, so to speak, between the donkey and him. But these camels were not camels that Avraham used but just camels that he owned and perhaps that is why they were not subject to this zchus. But maybe Avraham's own personal donkey was.
R' Yaakov Kaminetzky, in Emes leYaakov, has an interesting suggestion, seemingly based on one of the Kinos from Tisha B'Av. It seems that this "miracle" of the animals avoiding isurim was something connected to Eretz Yisroel. Maybe it was only in Eretz Yisroel that this happened. But in Chutz la'Aretz, Charan for example, the animals would need to be muzzled. The difficulty I found with this offering, though, is that this seems to be based on Rashi and Ramban's argument being later on in pasuk 34. But Rashi says already on pasuk 10, when Eliezer first left, which was in Eretz Yisroel, that the camels went out muzzled.
Sha'arei Aharon offers a different approach. Tosafos in Chullin seem to make a distinction between food that is itself forbidden in its essence and food that is not by its nature forbidden, but is forbidden due to external circumstances. The example in Tosafos is eating before Havdala where there is nothing wrong with the food itself but rather the time it is being eaten. Perhaps that is the difference here. The donkey of R' Pinchas ben Yair would not eat 'tevel'. Tevel is universally forbidden in its essence. But the food that Avraham's camels would have eaten was not forbidden by nature, but only because it belonged to others.
Have a good Shabbos
Eliezer Bulka