Learning Issues Hypothesis 1 What are the support mechanisms for the hock joint? Where are they vulnerable to injury? Tendon failure problems in dogs - what are they? What is most common? Muscle failure problems in dogs - what are they? What is most common? What is the effect of diet on muscle / tendon weakness? Deficiencies? Toxicity? What is the effect of exercise on muscle / tendon weakness? Too much? Too little? Hypothesis 2 What are the causes of bone weakening / failure? Congenital? Diet? Neoplasia? Infection? Activity? Injury? Why does bone weaken in these circumstances? What attaches to the end of the hock bone? Does the bone break there often? Why / why not? What would happen if the bone broke there? Hypothesis 3 What is the neurological supply to the hock support muscles? Where is it vulnerable? Is it possible to damage the motor supply and leave the sensory? How? Is this a known clinical problem? Are there selective nerve toxins that might do this? How? Tick toxicosis? Choline Esterase inhibitors?