My husband has had surgery 4 xs for an anal fistula and will need a 5th, is this common?

Not common: But not rare. Depends if the fistulas are in the exact same place and how they were treated surgically, how complex the fistulas were and whether the correct surgery was performed. Fistulas can recur if incompletely treated at the time of surgery. See a colorectal surgeon for more complex fistulas as your husband has. Also consider whether he has been tested for crohn's disease.