It's possible that you might be referring to something else, or the term is specific to a particular dog show club or region.
Could you please provide more context or details about what you're looking for? For example:
* What type of dog show are you referring to? (e.g., conformation, obedience, agility)
* What does the "AV" stand for in this context?
* What is the specific event or competition you're interested in?
With more information, I can help you understand what "AV open" might mean in your specific context.