There are two different competitions, one based on breed type and how the dog looks, and the other on obedience.
Trainor said the dogs' heads, expression and what they were bred for were important.
"A bull terrier will have quite strong cheeks because it's a dog that holds on to its game whereas a retriever will have no cheeks because it's got to have a light mouth to carry the game", Trainor said.
He said while the usual suspects like French bulldogs and golden retrievers still proved to be popular breeds, there was a noticeable increase in the smallest breed of all - the chihuahua.
Argentinian judge Frances Smith Moffat said first and foremost she looked at type, health, soundness and excellent temperament when judging.
Zola, an afghan hound, being put through her paces by owner Kerstin Strauss before winning the best of bred at the Black Hawk National Dog Show in Porirua. Photo / Mark Mitchell
Danielle Koolen, of Tauranga, receiving a lick on hthe chin from her siberian husky, Prima, at the Black Hawk National Dog Show in Porirua. Photo / Mark Mitchell
"Our point here is to be able to select the best of the future breeding stock."
Trainor said there was tension in the air on the first day of the show.
"There will be lots of nervous people out in the grooming room titivating their dogs up and making sure they're groomed to perfection and then coming out and handling their dogs."
17-year-old Olivia Ross is in the Junior Dog Handler final on Saturday with Samoyed Wicca.
Ross said she goes to dog shows almost every weekend after her Nana got her started at the age of 7.
Brooklin, a 14-month-old keeshond, during his 3-hour grooming session by owner Jeanette Wingele, of Helnsville, before judging at the Black Hawk National Dog Show in Porirua. Photo / Mark Mitchell
Ollie,a two-year-old bull mastiff, waiting to go into the ring during the Black Hawk National Dog Show in Porirua. Photo / Mark Mitchell
"I have a dog family and they're my favourite thing in the whole entire world. I come here for these dogs - they're absolutely beautiful and they mean the world to me."
Vicki Mills of Auckland has been showing bull mastiffs for 15 years after she got her first one as a pet.
Now she has 11 at home.
She said they were low maintenance compared with other dogs being shown.
"Before big shows like this they all have to be bathed and we put product oil on their coats so that they don't lose all the oils from their baths. Then grooming them, brushing them, putting a bit of shine on their nose and they're good to go."
