I thinkI know what is wrong but I want to check to see if any of you have had this issue and if you were able to cure it. I have 7 puppies that are a little over 12 weeks old. They are all up to date on shots and growing as expected but the last two weeks 1 puppy has slowly been losing control of its rear legs. She eats and drinks good but she isn't gaining weight nor is she losing it. the issue is if she walks 20 yards her whole body starts to stiffen up, her back starts to arch and then she loses all muscle control in her legs and falls out. During her lose of muscle control she visibly shakes. After a minute or two she regains muscle control and starts walking like nothing ever happened until she hits that 20 yard wall and it all begins again. Any help will be greatly appreciated

check backbone or around butt for tick.best take to vet.let us know what u find.good lk.