PHILADELPHIA — A small but growing number of dogs are being abandoned in and around a wooded section of the West Mount Airy area of Philadelphia — some of them found tied to trees or stakes. A few other dogs, as well as cats, are being dumped in other locations in Northwest Philadelphia, according to activists. The spate of creatures being discarded has worn on such people as Aminda Edgar, 45, a volunteer with the citywide nonprofit Green Street Rescue, which helps people adopt stray and homeless cats. She’s also created her own nonprofit Familiar Hearts Animal Society, which finds foster and …