Rachael,
THANK YOU for your very kind words.
But no, this situation has not occurred with one of mine so far !
However, I had the opportunity to do this for a friend of mine,
who had a "vigorous" animal such as yours is.
He happened to have a spare collar that wasn't being used
at the time, which we adjusted to fit the Dog's waist.
Though retired now, I've been in Engineering, as a Troubleshooter
for many years, and am used to thinking on my feet !