It sounds like Orin has hypertrophic
osteodystrophy which occurs in young rapidly growing large breed dogs; there is no cure, but the condition is self limiting with treatment consisting of pain relief and other supportive care (fluids for example).
Not exact matches
Three of the five diets tested proved to have abnormal calcium to phosphorus ratios
which can contribute to fibrous
osteodystrophy and hyperparathyroidism in puppies.
[34] Three of the diets had inadequate calcium - to - phosphorus ratios,
which may lead to hyperparathyroidism and fibrous
osteodystrophy in puppies.