Flea & Tick Collar for Dogs - With Precor Insect Growth Regulator (IGR). Kills fleas for 5 months and ticks for 4 months. Slow-Release Generator. Replace collar every 5 months for fleas and 4 months for ticks where there is an ongoing risk of pest infestation. Under conditions where pets are exposed to severe flea or tick infestations, it may be necessary to replace the collar more frequently. Replace this collar no more than once every 4 months.