Great little paper on knee joint thickness by Coleman et al. It confirms what we may have already known or guessed.... but it does it beautifully and in a highly quantified manner. The data is from humans, but I would expect that similar would be seen with doggies! Very sophisticated experimental techniques, and modelling with some lovely beautiful pictures (!) and well controlled data.
Read the paper here Coleman et al 2012
The difference in thickness is quite small between day and night, but certainly significant in the knees.
Snippets of the data are that men's cartilage is much much thicker than womens'... and of course, there is a significant correlation between cartilage strain and body mass index (BMI).
...So if you want nice thick knee cartilage; be a chap, spend the day in bed*... but don't eat too much!!!
*...but seriously: it is generally accepted that moderate exercise is good for healthy joints, but excessive weight is an absolute no no......
