The 14/02/12 patch was not good for this build of WW.
The passive change really stuffed up the sustain per hit that was so great with AS WW.
You will now need to build him with more lifesteal.
I will play around with his changes and maybe I will make a new guide.

Guide to how I build Warwick for jungling.
I was disappointed by the other Warwick builds and had to have my say.
This is my first guide.
This guide is for a attack speed Warwick.
Please try the build before rating, you will be presently surprised!

Please note this guide is all about fast jungling and speed farming. This build is not for you if you wait for minutes in a bush waiting for a good gank.

PLEASE COMMENT AND RATE IF YOU HAVE TRIED IT!

Pro's
Safe jungler
Hard to counter
Great at chasing
Great ganks post-level 6
Farm quickly
Can safely solo baron after madred's in above build.

Con's
Can CC'd down.
Less sustain compared to ad/life-steal WW
Is not ranged
Not as fast initial jungle as some others
More situational ganking required before level 6

The runes I have had a struggle with selecting, however the new hybrid pen runes may be suitable for the marks and quintessances.

Greater Quintessence of Desolation (or marks) are needed for early ganks and jungling.
Greater Seal of Armor are important for jungling.
Greater Glyph of Magic Resist for some protection against magic damage. These can be swapped for CDR or AS if you feel it is needed. MR/lvl may also be used.
Greater Mark of Magic Penetration (or quintessances) are needed for your madreds/maledy/wits-end magic damage.

Some people may disagree with my selection of masteries, and may want the runic affinity mastery for longer jungle buffs. However, i think warwick requires 21/9/0 for both magic and armour pen. The executioner mastery has great synchronization with blood scent in chasing enemies before they reach their turret.

The 9 in defence allows for the smite mastery and decreased damage from jungling and increased jungling speed.

Long Sword speeds up jungling and is a component of Madred's Razors (cloth armour not needed).
Madred's Razors are good for quick jungling especially with high AS.
Berserker's Greaves provide AS and movement speed. Increases jungling speed and ganking.
Malady & Wit's End have good attack speed bonuses while providing on-hit magic damage. They also increase your MR while decreasing the enemies.
Madred's Bloodrazor for %hp magic damage and more attack speed.
Warmog's Armor is an item I have lately used a lot, Warwick has low HP for a melee carry and this item gives him more then half of his total HP. Even if this item is obtained late game it can be easily fully stacked. It is helpful in situations where the enemy team has a high burst damage, or it can make you stay alive through hard CC (as your survivability only lasts when attacking).

Once this stage is reached you have massive attackspeed with procs on each hit.
(AS is just over capped with a level 5 Hunters Call, therefore I change my boots if i have the gold.)

This stage you only have four items out of six. The items following this are entirely situational.

Guardian Angel is a great item for when you are focused in team fights.
Bloodthirster provides good AD to complement your high AS, with good life-steal. Buy if you are confident you will not be CC'd or you don't need defense.
Force of Nature Provides good MR and boosts movement speed. Buy if opponents have high magic damage.
Frozen Mallet can be bought for health and a slow to guarantee they don't escape from you.
Sorcerer's Shoes, Mercury's Treads, Ninja Tabi can be swapped in place of your other boots in late game as you may need more magic-pen/MR/Armour.

Don't buy:
Hextech Gunblade's spell vamp does not work on item magic damage. It only works on his ult. Bloodthirster is a better item in place of it.

Skill order: R>W>E>Q

Eternal Thirst is warwicks passive and makes him very easy to jungle. It heals upon each hit.

Hungering Strike is quite useless as it scales off of AP. Get it once at level 2 and level it last. It gives less lifesteal then your fast autoattacks.

Hunters Call is the ability that makes warwick great. It it available for nearly every jungle mob and gank due to its low cooldown and provides a large attack speed steroid. I level this 1st.

Blood Scent is a great ability to chase enemies and reveal low hp enemies on the map. I level this 3rd. It is a toggle and should not be on if going in for a gank.

Infinite Duress is warwicks ult. It is great at initiating a gank if an ally has not got a stun. It hits 5 times with on hit effects (malady/wits-end/madreds) plus additional magic damage. It scales with AD. In team fights use it to suppress the main damage dealer.

I use Flash and Smite

Flash is good for getting in distance to ult or to escape.
Smite increases the speed of jungling and provides safer last hitting of buffs.

Alternatives:
Ghost can be used to increase movement speed, however i think blood scent is enough for catching enemies.
Ignite can also be used as smite is not 100% required for warwick.

For Warwick I start at wolves at 1:40. Move straight to blue (does not need a leash). Wraiths to golems to red (red can also be done before golems).

Get Dragon with the aid of your carry on the bottom lane for speed to avoid a gank.

Baron can be soloed once madreds has been purchased in the build.

Keep an eye out for struggling lanes. Warwick can easily push lanes back with his fast attack speed and madred's proc. The more cs you get the faster you obtain exp and gold and the better your ganks will be.

Initiate with Infinite Duress if you know the enemy will run. This suppresses the target allowing your allies to get a few hits in before they start retreating. They should have taken enough damage that they trigger Blood Scent giving you a burst of speed to finish them off with auto attacks and Hunters Call. I only use Hungering Strike when the target is out of melee range of a finishing strike.

If you are ganking and know the target will fight, I normally run in and trigger Hunters Call. Then I use my ultimate when the target starts running or you are low on health. Infinite Duress gives you max stacks of Eternal Thirst and gives a nice amount of life steal.

This build is not too expensive and does not require you to be fed to achieve.
I manage to reach full build in every game I play.

Please try this build before you comment and please leave comments on how to improve this guide.