Chendra had a miscarriage

Chendra, the lone Borneo elephant at the Oregon Zoo, has miscarried and is in treatment for TB. The zoo denies that her TB contributed to her miscarriage. However, an elephant vet said that another zoo waited til the mother elephant gave birth before administering TB drugs, so did the drugs play a part in Chendra losing her baby? Did the TB? Did the fact that she was old for a first pregnancy play a part, or that she was bred with an elephant who is not a Borneo elephant?  Or  was it just the ongoing stress of living in a zoo, especially now where she has been isolated for 8 months and will most likely continue to be isolated for many months to come. Read about it here.