I understand and sympathize. We tend to remember those who we lost when we were young or lost at far too young an age.;(
I have had four cockers in my life, and they are the best dogs, even though you said that your Mugsy didn't look as much like one. But they are cute, and loyal, and I also miss all of mine. My Barney lived until at least 18, though I will never know his exact age, since he was rescue. I still miss him, everyday. He was my perfect dog.;(
And I also had a perfect cat, who I also lost far too young. When my uncle died, his unpleasant wife got rid of his pets. Her relatives adopted his two dogs, but no one would take his two cats, so I did. Angela was the one I was meant to rescue, since I knew her and she had belonged to my aunt, who also died. She was a nice cat, but fairly reclusive. All anyone could tell me about the other kitty was that "it" was friendly. What an understatement! From the moment that this little cat did a delicate leap out of her carrier and into my life, I knew just how special she was. She came when she was called, loved everyone, except other cats, LOL! I could take her anywhere and she was just such a pretty thing. I hoped to have this cat, my cat of a lifetime, for 20 years. But then she got sick. I took her to a special hospital that my vet recommended, and she even put up with weekly acupuncture treatments! And this was a cat and she just fell asleep! But I did lose her, at age seven. And, like you, I am still mourning, at a very special life, cut so short. All the vet could say was that it must have been genetic. But I still miss my beloved Rhiannon, everyday.