typological question

Hi Linguaphiles! Do you know any languages that don't mark number (i.e. singular/plural) on pronouns, so that (for example) the same pronoun can be used in this language's equivalent of both the a- and the b-sentences below? 

1a. This dog obeys its master
  b. These dogs obey their masters 

2a. The dog is looking at itself in the mirror
 b. The dogs are looking at themselves in the mirror

Thanks! :)