I always seem to have trouble ganking with shyvana when i do ranked games, because they either just run away or flash etc. But when i see others play shyvana they can gank very effectively and i do not understand how they are completing this task.
The lane you are ganking must have CC, but Shyvana does have a lot of damage early which helps a lot in ganks, but you should not focus much on ganking when playing Shyvana( and you don't have exhaust or red), her strength lies in counterjungling and because of the early damage she has she can easily 1v1 most of the junglers in the game.
First of all, any jungler but Shaco is going to need help from his teammates. Ganking from a direction that allows your friendly laner to close is going to be critical. Don't come from in front of the enemy. Make sure you care coming in from behind, or at worst the side.
Second, compensate for your lack of slow with itemization. Shyvana's Double Bite has two chances to proc item effects. If you get a phage and get to Double Bite twice, you will almost certainly get a proc, allowing you to slow.
Finally, if you're going against a blue dependent jungler, try to counter jungle the enemy red buff. Getting theirs to start allows you to stagger your own buff, keeping your red uptime significantly longer early game, when you need it the most.
Get creative with your ganking routes, from behind enemy tower, sneak into bushes on the lane etc because without any cc/red buff/exhaust getting behind them is your best bet as your ult can push them further back from safety into your team mates.
Shyvana isn't picked for her ganking but her great clear times and high earl;y damage, which makes her a fierce counter jungler few can 1v1 her (Mundo, Noc can hold there own off the top of my head).
She makes a great pick vs slower starting, blue dependant junglers (Ammumu, Nautilus)