Sounds like a mild case of swimmers to me too. It could have been brought on by her excessive weight due to being a singleton. These pups are usually seen in litters of only one or two pups and they are generally a littler larger and less energetic than their littermates. It has been suggested that swimmer puppy syndrome incidence is highest in obese puppies and it isn't until the puppies start moving around, usually at one to 1-1/2 weeks of age, that the difference can be detected.
Treatment includes massage, vitamin E supplementation and suspension in warm water to get the limbs moving. Some breeders have also experienced success with putting the puppy in a sling a couple of minutes each day to get them used to touching the floor and walking.
If treated, most swimmer puppies recover completely by 15 weeks of ages and become perfectly healthy adults. Good luck!
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