We can see on the gravestone that the date of death of Matthew Modine's character is October 1991. So Fluke is about 3-4 years old when the main events happen. Such a dog is not old, nevertheless he has got some white hair around his mouth, like older dogs. I suppose that dog was at least 8 years old.
shareAccording to this profile at FindAGrave.com, the main actor dog (adult Fluke) was named "Buddy" and was about 6 or 7 years old during filming. Sadly he passed away from cancer in 1998, about a year after filming Air Bud.
http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=7731094
The dog named Buddy at that site doesn't look like Fluke... too "blonde" or something. And I thought the dog that played Fluke was named Comet? (At the end the credits say a dog named Comet played Fluke, and a dog named Barney played Rumbo.)
shareWhomever played Fluke was a Golden Retriever whose coat was colored darker for the role so he'd look like a mixed breed.
Anyway, now I am slightly confused since "Comet" is the dog from Full House who played Fluke...but I'm not sure if his real-life name was Comet? Or Buddy? O.o
And yes, a dog named Barney played Rumbo.
California Mountain Snakeshare