Laravel 5 get response header

I need to get the Http response Link Header from a Shopify orders http request. Unfortunately, the application is still using Laravel 5.1 and not the latest version.

(I believe) The call is being made using Custom HTTP Requests with some docs on this page: https://laravel.com/docs/5.1/testing

This is the call being made that returns order data but no other info.

$this->shopifyApiCreds->call($params)

This returns a response variable, but I do not know how to return any headers from this response.

Thanks!

via Chebli Mohamed