since there aren't that many Shyvana builds yet I decided to give it a try.
I created this build to make her painfull earlygame and still painfull lategame (not that lategame will be a problem in dominion)
This build has helped me so far and i havent had a bad match yet.

I take armor penetration just because they are awesome with any AD champion.
I take health per lvl because with the build her tankyness is only provided by the frozen mallet.
I take attack speed runes because her passive needs you to attack as much as possible
I take Movement speed quints because utility is important in Dominion

These masteries are set to my preference, I like DMG and Defence to be balanced so im prepared for most situations.

I like to take the brutalizer instantly since your dmg output (by the time you reach the first teamfight) will then be massive. when you hit your E and hit your Q afterwards (while your W is on) you will force them to backoff imediatly

I max my W first as utility is needed in dominion. everyone needs your help because a dragon in your team is to help. then you can decide on your own whether you like to go for your E or Q first. I like to go for my Q first since it does more dmg, however the debuff on your E might come in usefull for your teammates if you are failing on your own.