Short but sweet. I really enjoyed reading this!

Thanks for reading! :) I'm really glad you enjoyed! It's basically the first story I've managed to finish so I'm happy to hear that somebody got a kick out of it. :)

Oh I did! One tip though (and this is something a lot of people do without realizing it), stick to the same tense throughout or it detracts from the impact of the story. This is one example...

(Past tense)

He suddenly forgot about the delivery, about driving at all. Lifting his foot and pulling off the slightly torn sock... What he saw left him in utter shock. Paw pads, on his toes... And on the ball of his foot! His toes oddly splayed as he lifted them and stared. His foot looked like a paw! Covered in thick black and white fur! A quick look to his other foot and he suddenly confirmed the same thing there. What was going on?!

(Present tense)

Panicked, he looks up and uses his new paw-foot to jam on the pedal to try to pull over, and as he turns the wheel he can suddenly feel it slipping from him. His thumbs! They were disappearing! He barely manages to get the car pulled over in time with his rapidly shrinking hands, which were now gaining thick paw pads as his fingers shrunk down into small, white, dog-like paws. Tom takes his hand-paws off the wheel and stares at them in disbelief. Suddenly feeling his nose and face begin to stretch, he was turning into a dog?! Why?! 'Good boy...' he remembered the special instructions. Eyes darting to the pizza order as his vision shifted color. His nose, black and wet pushing out as his tongue grows thick in his mouth. Ears pushing out and legs forcing themselves up as they align in front of him. His pants and underwear ripping and tearing as his shirt seems to shrink with him! What?

Apart from this, your story reads very well indeed, and I look forward to reading more from you.

Thanks for this! I try to stay consistent and I guess I slipped as I got into it ;) ha, I'll have to update it when I get a chance. Thanks for the feedback! :)