I am currently fostering a liter of puppies for the humane society. They have a strange malformation of their front and back legs. I was wondering if you've ever seen this before?

I've come across your site quite a few times. I am currently fostering a liter of puppies for the humane society. They have a strange malformation of their front and back legs. The back legs are worse. I was wondering if you've ever seen this before and or have any ideas as to what it could be. It started as a litter of ten and I'm now down to 6. I've fostered puppies for 8 years and have only lost one... until now. Thank you for any and all help.

Jen