I have been lucky as I have never had a dog that would shy away from a goose, anything for that matter. When young and with limited to zero experience a dog will shy from a quail but exposure takes care of that quickly.
13 months is young but not a little baby anymore. Some dogs are just shy by nature and breeding. If it was me, I don't know your training history, but I really socialize my young dogs to everything in life. They follow me, live with me and do everything I do so they get lots of world experience at a very young age. They get to a point where nothing phases them. Your sort of past this but not to late to start. You need to build her confidence and boldness level with everything, not just the goose. She may never get that bold confidence. My buddies yellow English is like that.
Assuming it's not a weak Force Fetch and CC problem I would start her working on a dead goose, in the yard with her retrieving and holding it. Basically run her through a setup like traing a new pup to retrieve, training with geese, not bumpers, but be careful not to spook her more. She should pickup on dead geese easily. Live ones not so much. I know guys in your situtation that have dogs that never would tackle a live goose after that first bad event.
I would not send her on a live goose for awhile and I would not even send her on a dead goose in the field unless you have control of her and the situtation. Guess I am saying, don't set her up to form a pattern of failing or refusing on geese.
May not be an easy fix. Don
That's good advice. I wouldn't work the do on geese though. You say she doesn't have a lot of enthusiasm. Be careful. Start her on small birds like pigeon, make it fun, and SLOWLT work her back up to geese, keeping it exciting for her. Try to not make forced a part of it.
Your seeing what some of the problems can be when you buy a dog from dhole bloodlines.
You should also never have sent a youngster with little desire go for a goose. They're a tough and mean bird. A big mallard may do the same to her.
I hate seeing a game bird die of natural causes, unless I naturally cause it.