When a Talent Agency for Dogs loses its star, a secretary sees an opportunity for his own pooch. He “just” has to convince the owner, a bellicose alcoholic, the mid divorce casting director and the psychotic German client while the pooch needs to overcome its stage fright.
Maybe you can add an adjective to describe the main character (in this version of the logline, the secretary appears to be the main character).
The story is taking shape, now you can condense it even more to have a shorter logline. You don’t need to detail all the obstacles. It’s better to tell what exactly is the final goal, which is kind of implicit here (saving the business?). Think about the opportunity to include a time bomb like a major contract about to be signed.
Why do you say “his own pooch” when he’s not the owner of the pooch? Maybe it can be his pooch, so the goal would be to make his dog a star (I imagine the character’s arc: the secretary is obsessed about the idea of making a star of his dog and finally he learn to appreciate his dog for what it is).
One more thing, can’t you find a more interesting job for the main character? A secretary is very anonymous.
I suggest you to read this script which shares some vague similarities with your story:
(When a food scientist loses her company mascot (a ferret), she need the help of the pothead building superintendent to find the missing ferret).
Alas, the shift in the narrative focus doesn’t work for me because if the secretary is now the protagonist then there are no significant stakes. Even a comedy should have significant stakes. The protagonist urgently needs something — that’s the driving force for humorous scenes, all the desperate, frantic, and foolish measures the protagonist will take to get what she wants. And if she doesn’t obtain it, she will incur a great loss.
What is at stake for the secretary in getting her dog cast to sub for the “star dog”? Why MUST she get her dog cast? What does she stand to lose if she fails?
In this version, there are no stakes. There is no sense of urgent desperation, that the very survival of the boutique ad agency depends on casting the right pooch. Does the survival of the ad agency still depend on the outcome of the casting? If it does the logline should say so. It should be framed around those stakes. All the character and story elements in this version could still exist. It just a matter of framing them in the plot around the urgent dramatic need of the agency’s survival.