The dog picked up the puppy and carried it by the scruff (=back)of the neck into the house.scruffscruff /skrʌf/ noun 
WORD ORIGINscruff
Origin:
1700-1800 scuff ‘back of the neck’ (18-19 centuries), perhaps from Old Norse skoft ‘hair of the head’EXAMPLES FROM THE CORPUS
- As though some enormous beast nuzzled her then picked her up in its mouth by the scruff of her neck.
- Eventually he pulled her off and dragged her away by the scruff of her neck.
- He reappeared, grasping the unfortunate by the scruff of his shabby collar.
- One wondered when actor Ron Silver would finally shave the scruff he has been passing off as a beard.
- Quiss heaved the small attendant up by the scruff of its neck until its face was level with his.
- Three were dragged back on to the train and taken by the scruff of the neck from station to police car.
COLLOCATIONS FROM OTHER ENTRIES The dog picked up the puppy and carried it by the scruff (=back)of the neck into the house.
The dog picked up the puppy and carried it by the scruff (=back)of the neck into the house.PHRASES FROM THE ENTRY
1by the scruff of the neck if you hold a person or animal by the scruff of their neck, you hold the skin, fur, or clothes at the back of their neck2[countable] British English informal someone who looks untidy or dirty- It just caught me by the scruff of the neck and practically hammered my guts out.
- One had hold of the other by the scruff of the neck and had fetched blood.
- Three were dragged back on to the train and taken by the scruff of the neck from station to police car.
- Your eyes narrow against the claws gripping you by the scruff of the neck until you let your hook of anger go.