I would say its just like kids....different immunities and all. I raise my kids with my sisters....we had our first 6 weeks apart and Edmond (her son) was sick all the time, ear infections, colds, flus, everything else but my daughter Avery who was exposed ot the same thing she never got sick? they slept together bathed together basically raised like twins. SO Id say its just one of those things...I have 2 yorkies and neither have problems...well i did with my youngest but all reasonable explainations...He was hypo and came form poor conditions...but as soon as i got the hang of it he is VERY healthy. So I'd say its an individual thing not a Yorkie thing...Just my opinion hope it helps!
