Did they do imaging? Are they sure it is a shunt? If so, surgery is the best option. My Teddy Bear was diagnosed with a shunt as an adult and had surgery. He is fine now! Here is a link about when he was diagnosed:
http://www.yorkietalk.com/forums/sic...ver-shunt.html
Here is a great link about MVD and liver shunts:
https://vetmed.tennessee.edu/vmc2/Do...NAL-201304.pdf