Yup, it's about 4 months old when they start falling out. I remember the vet estimating Kobie's age (approx. 6 mo.) by looking in her mouth--she had all of her molars in at that time, and they're the last ones to grow. And with Eli, those sharp little razors he had through puppyhood began falling out at almost exactly 4 months. We'd find them in the oddest places, and some got knocked out during play (lots of blood--freaked us out ). But those adult teeth are soooo much easier on your skin!