
1) Barker 2) Distressed dog 3) Many a toy 4) Noisy pooch 5) One making shrill barks 6) Puppy, often 7) Shrill barker 8) Yassistant 
Found on 
https://www.crosswordclues.com/clue/yelper

• (n.) The tattler. • (n.) The avocet; -- so called from its sharp, shrill cry. • (n.) An animal that yelps, or makes a yelping noise.
Found on 
http://thinkexist.com/dictionary/meaning/yelper/
Yelp'er  noun  An animal that yelps, or makes a yelping noise. Specifically: 
 (Zoology)  (a)  The avocet; -- so called from its sharp, shrill cry. [ Prov. Eng.] 
 (b)  The tattler. [ Local, U. S.] 
Found on 
http://www.encyclo.co.uk/webster/Y/4
  No exact match found.