When I embarked on my first book involving animal characters, I was steered into reading similar books that soon proved to be dissimilar. Then I sought advice from professional sources: a professional editor, a representative of a writing guild, a language-arts professor-come-editor, and other successful authors (these last lumped together). Three of the four advised me to simply think of them as any other character, meaning, use quotations marks with dialogue and allow action to show what is happening. As for the said tags, no one really wanted to comment.
We all know the old-school teachings of telling—‘he exclaimed’, ‘she demanded’, ‘he shouted’, ‘Mary cried’—is outdated! Using said lets the reader carry on without particularly noticing the tag, or the jarring effect of further telling—‘he cried with chagrin’, ‘he screamed in terror’—instead of letting descriptive actions speak—‘His growl through clenched teeth brought them to alert’, ‘The piercing wail sent chills down the toughest spine.’
However since there is no norm for writing with animal characters, I did not use ‘said’ as a tag for my animals. Instead I wrote in the words of the dog(s)—‘he woofed’, ‘he yipped’, ‘he yelp-laughed’, ‘he grunt-barked’—all of which conveys the dog’s mood, level of excitement, and, to a degree, what has happened. Coupled with actions this sets the non-human characters apart from the human characters, easily discernible.
In my Long Dog duo for middle grade readers, most of the characters are dogs who conversed with each other. In the first Hercules and Big Bertha Mystery for young adults and older, the dog both narrates the story and tries to converse, especially with his human partner, so we see him talking and thinking. He’s simply a character, albeit a rather unique one, readers will cheer for.
You find out.