I’m scheduled to pick up The-Cat-Currently-Known-as-Mr-Marbles at 11 a.m. today.

But this rescue almost went off the rails yesterday when Marbles tested negative for feline leukemia virus, but positive for Feline Immunodeficiency Virus, or FIV. This was news that we didn’t expect. And it wasn’t good.

Here’s one online description of FIV.

Feline immunodeficiency virus, or cat FIV, is a retrovirus infection first discovered in cats in the U.S. The virus is often referred to as cat HIV or cat AIDS because it has a similar effect on felines. FIV-positive cats may have the virus in their system for years before showing signs of illness.

The virus works by killing or damaging cells in a cat’s immune system, often targeting white blood cells. The ongoing damage of FIV in cats eventually leads to a weakening of the immune system. Once that happens, cats with FIV can become vulnerable to secondary infections.

Little was previously known about how FIV was transmitted, and so the traditional advice was to avoid bringing an FIV-positive cat into a home to live with other FIV-negative cats.

Marbles’ vet visit wasn’t all bad news. The vet pronounced him otherwise quite healthy, with no indication that his FIV status has any current impact on his health. As you can imagine, this put us in a bind and we spent the rest of the afternoon struggling with what we should do. We had, after all, already made a commitment to Mr. Marbles, leading to his removal from the colony where he had been living. And, of course, we already have an obligation to Romeo and Kali.

I called a friend who is involved in cat rescue organizations. She said the current consensus, at least among these groups, is that FIV should not be a bar to adoption, especially if the cat exhibits no current symptoms. It is now believed that FIV is transmitted primarily through cat bites when cats fight. It is no longer believed to be transmitted through routine casual contact, eating, and grooming. She had an FIV-positive cat, and it lived a normal lifespan.

This mirrored the things I was reading online from other cat sites. For example, here’s an excerpt from the website of the Virginia Beach SPCA:

Historically, FIV- positive cats have often been considered un-adoptable, and are euthanized in many shelters. However, new research has shown that FIV-positive cats are in fact very adoptable, and can live the same lifespan as an FIV-negative cat. This research has also debunked the myth that FIV- positive cats cannot safely live with non- infected cats. That is why many veterinarians, including the feline medicine experts at the American Association of Feline Practitioners (AAFP), suggest shelters and owners never opt for euthanasia based on a positive test alone.

In one widely cited study, researchers followed a group of 138 cats, including eight FIV-positive cats, which lived together on a caretaker’s property. Of the cats that were available for testing throughout the study, none of the FIV-negative cats changed to positive, despite free interactions with the FIV cats. The researchers concluded that the virus is not spread through routine, casual contact even between cats living together.

I also texted our vet for advice, and she called back. Initially, she was wary and said she would hesitate to adopt an FIV-positive cat to join other cats. But she said she would check it out further, and talk to her colleagues, then get back to us. When she did, she mainly wanted to underscore that FIV can be transmitted in a cat fight, and that we would have to be careful. In the end, it’s a personal choice, she said, and rests in part on how much risk we are willing to take.

We’ve thought it over. It seems like the risk to the cats is manageable, and will require patience in introducing Marbles. But the larger risk is probably to us, since an FIV-positive cat may eventually require treatment for those other “secondary” infections, meaning more and higher vet bills. Fair enough. Also manageable.

Of the things I read yesterday about FIV, one stands out. It was advice aimed at other vets. It went something like this: “Treat the cat in front of you. Don’t treat the test.”

And the cat in front of us, currently known as Mr. Marbles, appears to be a sweet, friendly, healthy cat.

So we’re in. I’ll pick him up in a few hours.