1.Lice with head wider than thorax and chewing mouth parts .......... Trichodectes canis
2.Lice with head narrower than thorax and piercing mouth parts .......... Go to: 3-4

3. Eyes absent, 1st pair of claws simple and smaller than 2nd and 3rd pair of claws .......... Go to: 5-6
4. Eyes present, all tarsal claws are equal .......... Pediculus humanus
Note: While this louse only lives and reproduces on humans, the dog owner may bring in a specimen and ask if it was acquire from the dog.

5. Thorax distictly separate from the abdomen. Abdomen withOUT large tubricles. .......... Linognathus sp.
6. Thorax NOT distict from the abdomen. Abdomen with large tubricles. .......... Pthirus pubis
Note: While this louse only lives and reproduces on humans, the dog owner may bring in a specimen and ask if it was acquire from the dog.