Titus, I'm sorry about the loss of your dog. She must have lived a very long life, and was obviously loved and well-cared for, but even so, ANY loss due to death is an opportunity for our very deepest emotions and fears, the ones about mortality and isolation, to hit us hard. And, normally for all of us, to be immediately repressed by our brains as too scary to deal with.
Take the time to sit quietly, and feel these two emotions, and don't repress any of the associations that come up, not matter how strange, or or unconnected, or scary, that they might be. A death affects us in ways to go far beyond (or far deeper) than the immediate loss of the one person or animal.
Acknowledge ALL of the thoughts and emotions that come up, sit with them, and, finally, accept them.