The Sacramento Bee reported that McDonald was booked by San Jose police at 5:30 a.m. Sunday for "inflicting injury on a spouse or cohabitant".
McDonald posted $25,000 bail and was released from jail about six hours after he was booked. He is scheduled to appear in court on Sept. 15, the day after the 49ers play a Sunday Night Football game against the Chicago Bears in Santa Clara.
NFL commissioner Roger Goodell announced last week that the new punishment for those involved in domestic violence disputes would be six weeks for first-time offenders and a second offense would carry a lifetime ban.
Goodell's announcement came in the wake of his admission that Baltimore Ravens running back Ray Rice's two-game suspension for assaulting his then-fiancee in February was too lenient.
McDonald could face stricter punishment because the alleged victim is pregnant, according to Fox Sports.
The alleged incident involving McDonald occurred during his birthday party Saturday night that went into Sunday morning. Police officers arrived at 2 a.m., and said the woman allegedly assaulted by McDonald was bruised.
McDonald is expected to start at defensive tackle. He has 45 NFL starts in three seasons with 11.5 sacks. He is due to make $3.5 million for this season and $4.1 million in 2015 before becoming a free agent.
- - -
The Chiefs did not disclose terms of the deal, but multiple media outlets reported it was a four-year, $68 million contract, with $45 million of it guaranteed.
"It was a priority of ours to get this deal done and keep Alex in a Chiefs uniform long-term," Chiefs general manager John Dorsey said in a statement.
"Alex is a proven leader on and off the field. He is a special individual with a lot of ability, and we are fortunate to have him here."
In his first year with the Chiefs last season, Smith completed 60.6 percent of his passes with 23 touchdowns and seven interceptions while leading Kansas City to an 11-5 regular-season record and a playoff berth.
- - -
49ers guard Alex Boone is expected to end his long contract holdout and report to the team in the next 24 hours with a reworked deal, ESPN reported.
Boone, 27, will reportedly receive a new two-year contract that will replace his old one. It includes a salary increase plus incentives if he is named to the Pro Bowl.
The 49ers also will not be able to use their franchise tag on Boone when the deal expires.
Under his former contract, Boone was scheduled to make up to $4 million over the next two seasons.
Boone's holdout resulted in about $1.2 million in fines. It is not clear how the fines will be handled or if they would be worked into the new contract.
- - -
A day after the St. Louis Rams cut rookie defensive lineman Michael Sam, he became a free agent after passing through waivers, ESPN reported.
The Rams can still claim him and place him on their practice squad.
Sam is the first openly-gay player in the NFL. He has received national attention since coming out before the draft in May.
- - -
The Houston Texans acquired quarterback Ryan Mallett from the New England Patriots in exchange for an undisclosed draft pick.
ESPN reported that the Patriots will receive a sixth-round draft choice. It also reported that the Texans will waive quarterback Case Keenum.
The teams reportedly discussed a Mallett trade before the NFL Draft in May -- Texans head coach Bill O'Brien is a former Patriots offensive coordinator -- but were unable to agree on terms.
Mallett, a 2011 third-round pick out of Arkansas, was ultimately passed on the depth chart by rookie Jimmy Garoppolo this preseason and is entering the final year of his contract. Garoppolo will enter the regular season as the backup to 37-year-old Tom Brady.
- - -
The Cleveland Browns claimed three players off waivers, including running back Glenn Winston and guard Ryan Seymour, who were cut by the 49ers. The Browns also claimed former Seattle Seahawks guard Caylin Hauptmann.
Winston bolsters the Browns' backfield after Dion Lewis and Chris Ogbonnaya were cut by the team. Ben Tate and rookie Terrance enter the season as the team's primary ball carriers, with undrafted rookie Isaiah Crowell also surviving Saturday's roster cuts.
- - -
The Miami Dolphins claimed cornerback Sammy Seamster and safety Brandian Ross off waivers.
Miami cut wide receiver Damian Williams and safety Don Jones to make room for Seamster and Ross.
Seamster signed with the Baltimore Ravens as an undrafted free agent out of Middle Tennessee State, but was one of the team's final cuts.
- - -
The Indianapolis Colts claimed center A.Q. Shipley off waivers from the Baltimore Ravens and waived center Thomas Austin.
Shipley, 6-foot-1 and 307 pounds, has played in 30 NFL games (14 starts) over the past two seasons with Baltimore and Indianapolis.
- - -
The Minnesota Vikings claimed tight end MarQueis Gray and tackle Mike Harris off waivers and released linebacker Larry Dean and tackle Austin Wentworth.
Gray, who played quarterback at the University of Minnesota, was waived by the Cleveland Browns. Harris was waived by the San Diego Chargers.
- - -
The Tampa Bay Buccaneers claimed offensive lineman Garrett Gilkey off waivers from the Cleveland Browns and waived offensive lineman Josh Allen.
Tampa Bay also signed six players, including former track and field star Jeff Demps, to their practice squad.
- - -
The Buffalo Bills signed seven players to their practice squad: defensive back Deon Broomfield, linebacker Jimmy Gaines, wide receiver Caleb Holley, defensive end Ike Igbinosun, defensive end Bryan Johnson, defensive back Kenny Ladler and quarterback Jeff Tuel.
- - -
The Washington Redskins claimed safety Duke Ihenacho off waivers and waived safety Akeem Davis.
- - -
(Editing by Mark Lamport-Stokes)