The Kzinti were incorporated into the Star Fleet Universe where they became a powerful empire known as the Kzinti Hegemony, mortal enemies of that universe's Lyran Star Empire? - although it is alluded that the Kzinti and Lyrans share common ancestry, a claim both sides violently reject.
The instruction manual for the PC game Star Fleet Command clearly refers to the Kzinti by name in the background story for the rival race, the Lyrans?. This race is introduced in Star Fleet Command II: Empires at War? by simply changing the Kzinti Hegemony? to the Mirak Star League?.
The Kzintis in the SFU have traits setting them apart (no bat ears, sentient females, Kzinti/Kzintis as singular/plural etc.) from the Kzinti of Niven's works.
Sources: GURPS Prime Directive,