My coworker had to let her 13 yr old companion go yesterday. The quote that brought me much peace was sent to me by our holistic vet after Leo's passing.
"We who choose to surround ourselves
With lives even more temporary than our own,
Live within a fragile circle;
Easily and often breached.
Unable to accept its awful gaps,
We would still live no other way.
We cherish memory
As the only certain immortality,
Never fully understanding
The necessary plan."