In addition to a basset hound which sounded like Humphrey Bogart, the other animal shelter scene features dogs whose "additional voice characterizations" were impressions of James Cagney, Edward G. Robinson, Peter Lorre and Mae West.
When Tim brings the dog into the bar for the second time he pulls a barstool out for the dog. A crew member's hand is clearly visible grabbing hold of it at the bottom to keep it steady.