(CNN) By the time Greg Manteufel, 48, reached the hospital in late June, "my face was all red and blue, and it started going down the rest of my body," he said.

"My arms, my chest, everything was changing colors," said Manteufel, of West Bend, Wisconsin.

Manteufel initially thought he had a bad case of the flu, but in his blood, doctors discovered a type of bacteria normally found in the mouths of dogs and cats.

These bacteria rarely make humans sick, but Manteufel's infection -- and how his body responded -- caused surgeons to amputate parts of his nose and limbs, including both hands and feet.

"Just do whatever you have to do to save my life," Manteufel recalled telling his doctors at Froedtert Hospital in Milwaukee.

The type of bacterium, Capnocytophaga canimorsus, is "completely normal flora of a dog's mouth and usually doesn't cause any sort of significant disease. However, in the wrong place, at the wrong time, in the wrong patient ... it can lead to severe infections -- but very, very rarely," said Dr. Stephen Cole , a lecturer in veterinary microbiology at the University of Pennsylvania School of Veterinary Medicine. Cole was not involved in Manteufel's care.

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When the bacteria spread to humans, they do so through bites, scratches or other close contact with dogs and cats, according to the US Centers for Disease Control and Prevention.

In rare cases, patients like Manteufel can develop sepsis. They can also develop a complication, as he did, known as disseminated intravascular coagulation . In this disorder, small blood clots form rapidly and can then plug blood vessels and block normal circulation.

"The infection cleared fairly quickly" with antibiotics, said Dr. Silvia Munoz-Price , an infectious disease physician who treated Manteufel at Froedtert Hospital. "However, down the road, he developed poor circulation, poor blood flow into his arms and legs.

"And the blood flow was so low that he developed a process called gangrene. Basically, the tissue dies and becomes blue," said Munoz-Price, also an epidemiologist and a professor of medicine at the Medical College of Wisconsin.

Doctors knew that they couldn't save his arms and legs. What they didn't know was how an otherwise healthy 48-year-old became infected in the first place.

Those at greatest risk are people with weakened immune systems , such as cancer patients and people who have had their spleens removed, according to the CDC.

"I've been basically [the] healthiest person in the world so far up to this point," Manteufel said. "They said I could have hit the lottery five times in a row in one day before I should have gotten this bacteria in my body."

Munoz-Price said, "we are not certain how it ended up in his bloodstream" and estimated that she sees only a small handful of cases a year.

However, she added that "we are hypothesizing that it was because of a dog lick," because Manteufel had no obvious injuries and because he had been in contact with dogs, including his 8-year-old pit bull.

"We will probably never know," she said.

Should you be worried?

"I have a dog. Many people have dogs, and most of us will never have problems with infections related to our pets," Munoz-Price said.

Cole agreed: "Every time your dog licks you, you may come into contact with this bacterium, but the vast, vast, vast majority of times, that causes absolutely no problem."

Capnocytophaga bacteria have been detected in up to 74% of dogs, according to the CDC.

C. canimorsus is not on CDC's list of reportable diseases, and experts say it's hard to pin down numbers on how rare these infections are. A 2015 report found fewer than 500 laboratory-confirmed cases that had been reported since 1961, though the bacterium was not officially named as a new species until 1989.

Munoz-Price said that she sees aggressive infections like Manteufel's much more frequently caused by bacteria that already live in humans, not dogs or cats.

When it comes to our pets, Cole says, the benefits far outweigh the risks.

"We know that pets have wonderful health benefits in our life," he said. "We know that they can make us happier, healthier people as long as we approach that in a safe way."

That means practicing good hygiene with your pets, Cole said, including not letting pets lick open wounds or sores, washing hands and seeking proper medical attention for bite wounds.

"I would hate that anyone would think that this is a reason to give up their pet," he said.

'I'll always love dogs'

Manteufel still has a long road ahead. After more than a dozen surgeries, he's planning on getting prosthetic limbs, and doctors will use cartilage from other parts of his body to repair his nose.

He has also been working with rehab specialists learning to adjust to his new life. A GoFundMe page was also set up to help with costs.

Physical therapist Cheryl Vorwald helps Greg Manteufel with his rehabilitation at Froedtert Hospital.

Manteufel doesn't remember much about being sick -- "I was kind of out of it," he said -- but since he went public with his story, others across the country have reached out with their own.

"We were amazed of even some people that came out that had this particular bacteria because it's been so rare, and we never heard of it," said his wife, Dawn. "We found out there was two people in Wisconsin alone with the same situation."

With his wife and son by his side, Manteufel is focused on staying positive.

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"I have to be strong for them, and they're being strong for me," he said. "I got to just keep looking forward and hope I get better every day."

And he still has a soft spot for dogs, including his pit bull -- who he doesn't believe led to his infection. (She isn't much of a licker, he said.)

"I can't just stop liking dogs because this happened," he said. "I'll always love dogs."