The 49ers are about one second away from announcing their pets’ heads are falling off.

A brutal collapse Sunday against the Rams led to an even bigger gut punch Monday with three notable injury developments, including the loss of a prized free-agent acquisition.

Sidelined star running back Christian McCaffrey flew to Germany to meet with a consultant regarding his lingering Achilles tendinitis, defensive tackle Javon Hargrave is likely out for the season after suffering a partially torn right triceps and quarterback Brock Purdy is day-to-day with back soreness, 49ers coach Kyle Shanahan announced Monday on his conference call.

McCaffrey is on injured reserve with said injury that he sustained during training camp.

“I know he’s going to see a specialist that I believe can help him with his Achilles process,” Shanahan said. “I think he’s doing that over these next few days, and hopefully, it’ll help.”

While the Chiefs are 3-0 to start their three-peat chase, the losers in last year’s Super Bowl are 1-2 and are struggling to keep their stars on the field.

McCaffrey hasn’t played yet this season after suffering his injury, surprisingly being inactive for the Week 1 win over the Jets before landing on IR ahead of a Week 2 loss to the Vikings.

His earliest return can come in Week 6 when the 49ers face the Seahawks on “Thursday Night Football” on Oct. 10, although Shanahan did not provide any details as to whether that’s a feasible timeline.

Jordan Mason has played well in McCaffrey’s absence, but the 49ers miss their do-it-all back.

San Francisco will hope it can find a viable replacement on the defensive side now that Hargrave will be sidelined for at least the remainder of the regular season.

Shanahan said there’s a chance the veteran could be back “late” in the playoffs, should the 49ers advance that far.

Hargrave is in the second year of a four-year, $84 million contract, and plays an important part of a 49ers’ pass rush that is meant to be one of the team’s strengths.

The 49ers’ defense is off to a rough start by its lofty standards, allowing 23 points per game.

In Sunday’s 27-24 loss, the 49ers yielded 13 unanswered points in the final 6:15 to blow a 10-point lead.

“It’s a big one,” Shanahan said of losing Hargrave. “I thought he had his best game yesterday. I thought he was a huge factor, really affected the quarterback in that game. It’s a big loss. He’s one of our better players. He was definitely going in the right direction and was going to have a big year.”

Purdy’s situation seems the least alarming, with Shanahan saying an MRI exam came back clean and the hope is he’ll feel better by Wednesday’s practice.

The 49ers are the biggest favorites in Week 4, laying 10 points at DraftKings for their home matchup against the reeling Patriots (1-2).