"It was great to qualify at Tattersalls for the show, but the competition was tough over there," says Rooney.
Now in foal to the thoroughbred Golden Lariat, the eight-year-old will contest the stinted mares' class, as well as the lightweights once again.
To bring such a large number of horses to Dublin is no mean feat, and Rooney is grateful for all the help she receives from family and friends.
"My mother Maureen is a great supporter and will be there. I am still short a rider for one horse, but hopefully that will be sorted shortly."
A native of Co Westmeath, Rooney has been involved in horses all of her life.
From the early days, she received an excellent grounding from the legendary Iris Kellett, before spending a few seasons with Pat Creighton, sister of British show jumper Peter Charles.
From a farming background, Rooney is still based at the family farm, where she operates a busy yard of show horses and liveries. Her brother Michael runs the farm itself.
Producing horses for owners is an important part of the business, and Rooney is grateful each time animals are returned to her for the show season.
"I am lucky to have some good owners," she says, also acknowledging John Roche, and Ciara Greaney.
Little Falls, a five-year-old mare by Grey Laughton, was recently purchased by Greaney, but Rooney retains the ride until after Dublin, during which they will compete in the large riding horse class.
Rooney's own home-bred mare, the well-named Eye Candy, is entered for the small riding horse equivalent. The seven-year-old by Ricardo Z, who won at Mullingar two weeks ago, is a half-sister to the heavyweight gelding, Middleburg.
Both are out of the premier mare Accelerator, who is by Beau Royale and won many classes over the years for her owner.
Middleburg, a four-year-old by the Irish Draught stallion Westfield Bobby, won on his first outing at Balmoral in May when collecting the tricolour in the ladies' astride championship.
He was also third in the heavyweight class at the Northern venue, but in recent weeks stood at the top of the line at Clonmel Show.
No Dublin Horse Show would be complete without Rooney having entries in all three weight classes, and John Roche's mare Assagart Mistress is being aimed at the middleweights on the third day.
By the deceased sire Kings Master, the four-year-old was third in her in-hand class at the RDS in 2013 and her connections will be hoping for further laurels as she competes under saddle this time round.
Over the years Rooney admits her own horses often have to take a back seat when clients' horses start arriving into the yard, but this year she is delighted to be in a position to take four horses of her own.
This quartet includes The Journal, a six-year-old lightweight home-bred gelding by the thoroughbred Seabrook.
"He has only had a few show outings but has hunted quite a bit," says Rooney.
She has hunted regularly with the Westmeath Foxhounds over the years, and many of her horses have gained much experience in the hunting field.
One horse who is now enjoying life with the Pytchley Hunt in England is The Journeyman.
Bought by Rooney out of Goresbridge as a three-year-old, the gelding won at Balmoral and the RDS in 2010 before being sold to the hunt's joint-master Neil Holloway.
"All the horses here are hacked out, lunged and schooled over cross-country fences locally to keep t hem ticking over. It is excellent to get them going forward.
"And they are all fed on Top-Spec which keeps them in peak condition," Rooney said.
All going well, Rooney will be able to stock up on further products from the feed company who are to sponsor the hunter classes at the RDS for 2014.
Squads announced for Millstreet
HORSE Sport Ireland has confirmed the dressage, eventing and show jumping squads for the 2014 European Pony Championships in Millstreet, which take place from July 30 until August 3.
The pony dressage squad is named as Katie Burns (Caracas II), Alana Cazabon Sullivan (Schermeer S Hof Arendsoog) and Linnea Larkin (Goofy).
The pony eventing squad is Sophie Buller (G Maha), Fionn Clarke (Black Velvet Band), Patrick Dennehy (Rose Down), Lucy Hancock (Newtown Westie), Shannon Sheridan (Drop The Subject) and Mary Smiddy (Mr Hale Bob).
The squad reserves that will compete as individuals are Emma Kennedy (Laburnum Ineer) and Maresa Ronan (My Rustic Clover).
The four additional individual riders are Lucy Arkwright (Sally McNally), Jessica Kuehnle (Fernhill Ruby), Isabel Persse (Mr Blueskies) and Alex Power (Keredern Little Heather). The pony show jumping is named as Nicholas Connors (Mighty Patch), Susan Fitzpatrick (Rock Dee Jay), Grace McHugh (Cassandra Van Het Roelhof), Sean Monaghan (Attyrory Rebel) and Michael Pender (Doon Laddie).
The reserve is Kayleigh Soden (Castle Hill King).The team to compete in the Nations Cup will be selected from these five combinations.See www.millstreet2014 for competition results.