2008 to 2021! 
I'll be impressed if anyone can remember my older ones. Cue long description few people will read:
2008
Didn't know what a fursona was, at this time I was a warrior cat, and I made a raccoon to represent out of character interactions! I did alot of roleplaying during this for warrior cats, and wolves, met lots of friends I wish I still had contact with. At this time I was also mostly into drawing pokemon. Recently revamped raccoon: https://toyhou.se/3410934.kaax 
2009
This year was a mess of fursonas, I just found out about the furry fandom and had inspirations like Blue/Miiroku, and Ash/Skeleion. I was also a weeb near the end there lol. These were meant to be mastiff/wolfhound/great dane mixes cause I wanted to be t a l l but never did the anatomy right rip. This was also middle school so it was a weird time. Also had my first heartbreak so that explains sad one, would often roleplay as these ones so roleplays would change my sona often.
2010
Red and black is cool right?? right?? I owned a black and red fingerless sleeve like that and it was everything to me, then my school made me stop wearing it cause they thought i was self-harming and hiding scars?? idk lol It was still worn on my fursona which mattered. Also dyed hair and arm/leg tattoos were introduced! 
2011
Back to weeb, loved FMA and started really like My Chemical Romance and BOTDF (ew). Tried to look emo and cool, didn't really work rip.I would switch around this and older ones occasionally.
2012
Full irish wolfhound, didn't last long and I was actually drawing other characters at the time, not much to say in 2012 but that I was getting into MLP and less into furries.
2013
Another dramatic change, a full pug. Most used on tumblr, and not even that much. I just really liked pugs then and wanted to show that tired wrinkled face more lol.
2014
Pony! Furry stuff took a sideline as I was caught up in tumblr pony blogs and mlp roleplays, but I had a pug/raccoon as my fursona when I wanted to draw here, didn't last too long. This also introduced the hat which was a trademark of mine more or less, even got recognized at an mlp convention cause I wore it! Late 2014 I decide the dark gloom wasn't me anymore and as my oldest dog, a golden retriever, was starting to age, I wanted to keep her close, so I did the biggest change to my fursona. Also introduced the raccoon tail. The pony can have a timeline herself tbh lol but here's her now https://toyhou.se/505008.kayla 
2016
Lost my hat, literally couldn't find it for like 3-4 years. Tried a brighter palette and brought back the glasses but it just wasn't doing it in the end. Was busy with college and trying to keep my MLP blogs alive, which didn't work in the end.
2019
Present day Kaydog, I really feel like this is me. Simple, rather natural, and everything I want in a fursona. I have others that aren't my main, which I use when I feel just not myself exactly, but this design is def me.