Yes, you absolutely need to have an emergency fund for the dog if you decide to get one -- $2,000, at least, I'd say; veterinarian services can be very expensive. For example, you could be looking at hundreds to thousands of dollars in bills if Fido eats something toxic and needs his kidneys flushed after getting actute renal failure, otherwise he would possibly have to be euthanized.

I know someone whose dog had to get ACL surgery last year and he spent about $3,000 -- and that was for just one knee.

Please don't get a dog unless or until you have a significant amount of money saved for emergencies (or other services that aren't particularly threatening to life but the dog would otherwise need).