She’s raced on the dirt and the turf. She’s taken on the boys and shown her heels to her fellow fillies more than once. Nitrogen has shown over and over what grit, grace, and versatility look like, building a record of nine wins, six seconds, and three thirds from 18 starts with an Eclipse Award and a Sovereign Award to her credit in her three seasons on the racetrack.

Autumn Lavertu gallops Nitrogen (Eclipse Sportswire)

Owned by the Green family’s D.J. Stable and trained by Mark Casse, the bay filly has become a fan favorite thanks to her performances on the track and her personality in the barn.

But what makes this daughter of the late Medaglia d’Oro tick? Casse Racing’s Samantha Bussanich, Caden Arthur, Ryan Keefe, and Autumn Lavertu shared their insights on Nitrogen ahead of her start in the $2 million Longines Breeders’ Cup Distaff Oct. 31 at Keeneland.

When we talk about these equine athletes, we know that, like people, they can be one way in their home, the barn, and another at work on the racetrack. One horse might be a softie in their stall and a tiger when under saddle while another could be tough when they are at rest and pliable on the track. In Nitrogen’s case, “She’s a puppy dog in the barn. She just loves attention and treats,” said Caden Arthur. “If you want to do anything with her, take her outside to graze; she loves that idea. Anything in the barn area, she’s up for.”

“She’ll liven up if she hears a peppermint wrapper, but she eats anything really. She loves carrots nowadays. Carrots are a new thing,” Bussanich said. “Anyone who has food for her is her best friend.”

The filly has also raced everywhere from California to New York and Kentucky to Ontario and has shown herself to be an easy traveler with few quirks. Yet, when she was stabled in a stall with a gate in Saratoga, Nitrogen did develop an interesting habit.

Nitrogen builds a nest at Saratoga (Casse Stable)

“Because she had a gate, she’d always pick her straw up at the front of her stall and make what we called her nest on her door,” Bussanich said. “I don’t know why she would do that up there, but she’d have straw all on the gate or in her forelock, in her ears.”

Nitrogen also has proven to be something of a curious cat, one of those horses who likes to know what is going on at all times. Because of that, visitors might not see her lie down as some horses will. “The other week, Sam was asking her groom here if he’s ever seen her lay down because we never have seen her. He said that yes, he has, but she normally does it like when it’s really quiet or like in the evenings,” Lavertu said. “She’s not one that we’ve ever really seen lay down.”

On the racetrack, this curious cat can be more like a lioness. As her exercise rider Lavertu observed, “She actually has kind of a stoic personality. Nothing really gets to her, but every once in a while out on the track, she’ll really pull if a horse passes her breezing or something. But usually she’s kind of a pony to gallop, very classy filly.”

“She’s the same every day. She doesn’t change at all. And she always stays really easy to gallop and jog, and she’ll stand out there forever if you’d let her, just to check everything out.”

“She loves standing,” Bussanich said. “She will stand and watch everything for as long as you want. And that’s something that we’ve kind of noticed along the way: the good horses like to just sit and watch and observe.”

On race day, Nitrogen is not one to get worked up in the paddock waiting for saddle and rider. As Arthur describes her, “She’s always really calm. Then walking from the saddling ring out to the racetrack, that’s when she starts getting on her toes a little bit because she knows it’s about to be go time. Before then, she’s all class. She just wants to stand there, and you just keep petting her and give her some love before we go out.”

Nitrogen, the love bug (Coady Media)

This champion filly also stands out in how she has won on both dirt and turf, something that few horses do. That puts her in company like California Chrome, Tepin, Wise Dan, and others, and no doubt Nitrogen will be one of those names that comes up in future conversations.  

Bussanich attributes that flexibility to her pedigree: by Medaglia d’Oro out of the Uncle Mo mare Tiffany Case. “I think being by Medaglia, he was such a versatile stallion. He could throw anything, and as Mark always says, these good horses can run on anything. Luckily, we have owners in Len and Jon Green who, when the opportunity came to run her on dirt, said, ‘Go for it, let’s try it out.’ She wouldn’t be where she is today without owners like the Greens. We’re here today because of that decision to run her in the Wonder Again [Stakes].”

The bay filly, with her wee brushes of white on her forehead and nose, is 16.3 hands of love bug and lioness, which makes it easy to see why she has become such a fan favorite. Those qualities have also made her a beloved part of the Casse barn and D. J. Stable, so much so that Casse received almost as many congratulations about her second behind Sovereignty when facing males in the Grade 1 Whitney Stakes as he did when he was inducted into the U.S. Racing Hall of Fame in 2020.

As we count down to another Breeders’ Cup and anticipate her taking the track for the Distaff, those who know her best appreciate who Nitrogen is and what she brings to the team.

As Lavertu puts it, “If every horse was like her, this would be the easiest job.”