Shana, I tried to pm you and my computer died. I am so very sorry that Penny got hurt. I know to you it looks really bad, but from what the pic shows, it looks like a nice clean cut.
The very best wound treatment we have found was one that was recommended by our horse vet - a product called Herbal Wound Spay - manufactured by a company called Laid in Montant. Their website is:
www.laidinmontana.com . On more than one occasion I have seen it heal horrid jagged wounds with little or no scarring.
Give Penny some extra lovin, and you, girl, need a hot bath and a glass of wine!