From the Daily Mail:
In articles published on 23 and 26 May 2008, we gave the impression that Mr Gest had contracted a sexually transmitted infection and alleged that he had Liza Minnelli’s dog killed without her knowledge.
This was wrong. David Gest has never had a sexually transmitted infection and did not have Ms Minnelli’s dog killed.
We apologise to Mr Gest for any embarrassment caused.
Source: Regret the Error

He probably killed the dog performing a sexual act on it, that's where his STD came from…….
ROFLMAO
Awesome.