Incisors:  The deciduous (baby) incisors are usually lost from 3 – 4.5 months (12 – 18 weeks) of age.

Canines:  The deciduous canines are usually lost from 5 – 6 months (20 – 24 weeks) of age.

Premolars:  The deciduous premolars are usually lost from 4 – 6 months (16 – 24 weeks) of age.

Molars:  The deciduous molars are usually lost from 4 – 7 months (16 – 28 weeks) of age.

As with kids (humans), young dogs (and cats) have deciduous teeth that they lose as they develop into adults.  Sometimes, you will even find these deciduous teeth as they lose them. 

At other times, not all the teeth are lost as your pet develops (i.e. the deciduous canine teeth).  Therefore, it is recommended to have these teeth removed to allow the permanent (adult) teeth to fully develop and to lessen the likelihood of malocclusions.  Also, your pet is likely to have more severe dental disease issues by having these deciduous teeth remain.