craftgrrl | Pet (dog) clothes patterns/ideas/instructions?

I'm looking to craft a little t-shirt or tank top for my dog, since those puppy apparel websites tend to be a little outrageous in their prices.

However, I've had a hard time trying to find any sort of sewing pattern or instruction for making this type of thing.

I searched the FAQ here, I've searched craftster.org, Google, and Yahoo. Maybe I'm overlooking something, but it has just been difficult to find a legit link to an actually site with instruction.

Does anyone have any idea how I would go about making a t-shirt or tank top for my dog? Shes a medium to large sized dog (50lbs). If you have a link or pattern, that would be even more fabulous.