My mom's labrador retriever had a parvo combo vaccine at 6 or 7 weeks, then 12 weeks, and will get another combo vaccine this Sunday at 18 weeks. The timing between the shots isn't the ideal 3-4 weeks. (The dog is only going in at allbecause of me reminding my mom!!) After having received 3 sets of shots - do you think he'll be adequately covered? Or will he need another booster at 22 weeks?