The teenager was held by detectives in the wake of the suspected arson attack on Manchester Dogs' Home on Thursday night, which has been described as "sickening" and "harrowing" by staff and firefighters.
Greater Manchester fire and rescue service said 53 dogs had died, while about 150 were rescued and have now been taken to the centre's sister site in Cheshire.
"A 15-year-old boy who was arrested on suspicion of arson has been bailed pending further enquiries," police said in a statement.
Meanwhile, donations to the dogs' home have flooded in, with a JustGiving page raising more than 1.2 million pounds.
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During the blaze, local people tried desperately to break into the compound after a passing police officer raised the alarm. Hundreds rallied round to provide refreshments, animal food and other help for the dogs that were rescued.
Lisa Graham, who works at the kennels, said: "To think that for the length of time we've served this community and the many generations we've been serving this community and that one of them would come and do this to us is sickening.
Station commander Paul Duggan, from Greater Manchester fire service, said: "A number of the local people had made an attempt to try and rescue the dogs because, obviously, they could hear them in some distress.
He said: "You've got a number of members of the public doing a very charitable thing, trying to help the dogs, but obviously it's a risk to them. All in all, a fairly complex and complicated and, also, harrowing incident."
The Manchester Evening News said it launched the appeal for donations and it had raised more than 50000 pounds in under 24 hours.