He should receive a second booster at the age of one year. (vetinfo.com)
The second booster is 2nd FVRCP combo and 1st leukemia and the third set is 3rd FVRCP combo, 2nd leukemia and rabies. (royaloakpetclinic.com)
It also seems to be associated with a lower rate of vaccine reaction, and serial boosters are not necessary to impart a sufficient immune response, whereas, with the injectable bordatella, for puppies and first time adult dogs that have never before been vaccinated, need a second booster vaccine is necessary to provide sufficient protection. (web-dvm.net)