Riding racehorses has become an equal opportunity occupation, with equal opportunity for success -- or disaster.

Michelle Higley, 26, from Anaheim, Calif., had had a big week at Centennial race track, Littleton, Colo. She had posted three firsts, three seconds and three third-place finishes on 13 mounts; moved within 10 wins of elevation from apprentice to journeyman. But in a Saturday morning workout, easing her horse, as she stood in the irons, she lost her balance, pitched forward onto the track and was kicked in the head.

She never regained consciousness and died Sunday.

It was one week since male rider Avelino Gomez, veteran of more than 4,000 winners, was killed in the Canadian Oaks at Woodbine. It was also the day Michelle Higley was being announced as jockey of the week at Centennial.

"A complete freak accident," said trainer Jack Bland, who later Saturday saw a four-horse accident in which three jocks suffered lesser injuries. "Those horses and riders went down four times as hard as Michelle," he said.

Meanwhile, Karen Rogers, the one considered the best female jockey in the 11 years since Marylander Kathy Kusner cracked the sex barrier, is making plans from her hospital bed in Monmouth Medical Center, Long Branch, N.J., to pick up where she left off. But that's several months away.

Rogers, just 17 but already a veteran of Meadowlands (leading apprentice in 1979) and Aqueduct (10 winners in 126 mounts), escaped paralysis when her horse clipped feet with another last Monday at Monmouth Park and she fractured three vertebrae. She has gone the whole painful time without painkillers because she also suffered a concussion but now the ache has gone and she is due out to go to her home in Oceanport this week for recuperation. She must wear a cast three months before beginning rehabilitation.

She can hardly wait. . .

When Dave Kingman went on the disabled list early last month, it wasn't only from baseball. The Cub slugger also went the next three weeks without filing his regular Sunday column for the Chicago Tribune -- that endeavor begun this spring that engenered so much controversy among the "real" sportswriting set. Well, the writers can relax. King Kong returned to the field on Sunday, his bad shoulder better (still, he muffed a fly ball against St. Louis) but he won't shoulder pen or typewriter anymore. The Tribune has announced Kingman's voluntary retirement, "to concentrate on baseball" . . .

The Boston Celtics have put aside their threats of temporary removal to Connecticut or Rhode Island while their new Revere, Mass., arena gets built, owner Harry Mangurian announcing a new two-year rental agreement with Boston Garden . . .

Canada's federal revenue department has won a court order to seize $2,049,358 due Sugar Ray Leonard Inc. as part of the former welterweight champ's take from the Roberto Duran bout in Montreal June 20. But a spokesman for the Olympic Installation Board says the pride of Palmer Park probably needn't worry, that under a 1942 Canada-U.S. treaty Leonard must pay only U.S. taxes on the $4.1 million due him from the OIB. Financial adviser Mike Trainer no doubt had that angle covered all the way; nevertheless, until the court order is dissolved, Leonard cannot cash the full amount of a $3.5 million letter of credit issued by the Royal Bank of Canada on behalf o the OIB. . .

Onward and upward for yet another American University sports publicist. Off to become a sportswriter for the Los Angeles Herald-Examiner July 15, a FanFarish bon voyage to Josh Rosenfeld . . .

Mike Menchel, onetime Redskin publicity man who moved on to NASL and MISL, currently is administrative vice president of Major Indoor Soccer League's Baltimore Blast -- told you they'd come up with a catastrophe of a nickname after moving from Houston. And calling for free agents with pro aspirations to hie themselves to the Civic Center 1-3 p.m. today or 8-10 on Wednesday for tryout camp. Season starts in November. Already the Blast boasts one of Rosenfeld's AU prides, conference MVP Luis Calderon . . .

Jeanette Kelly, Dunbar's middle-distance running champion, is in for a treat Wednesday at the New York Athletic Club. When O. J. Simpson passes out Hertz No. 1 awards for outstanding '79-80 feats to one high school athlete from every state plus District of Columbia and Puerto Rico, Kelly will be D.C.'s pride, for her 880, mile, two-mile triple in a three-hour span of the Interhigh meet. Dinner with Juice caps two days of NYC doings for the No. 1s, starting today. For Maryland winner Darryl Gee of Oakland Mills, and now the Cosmos, just another day in the big city.