𝗞𝗶𝘁𝘁𝗲𝗻 𝗖𝗼𝗹𝗱 𝗪𝗮𝗿𝘀 — 𝗥𝗲𝘀𝗲𝗮𝗿𝗰𝗵𝗲𝗿𝘀 𝗕𝗮𝘁𝘁𝗹𝗲 𝗦𝗻𝗼𝘁𝘁𝘆 𝗡𝗼𝘀𝗲𝘀 𝗮𝗻𝗱 𝗣𝗮𝗶𝗻𝗳𝘂𝗹 𝗘𝘆𝗲𝘀

SHELTER MEDICAL (Davis, Calif.) – Let's face it, life as a homeless kitten sucks, especially when your eyes hurt and you have a snout full of snot. We're talking about feline upper respiratory infections (URI), common crud that sweeps through multi-kitty hangouts like animal shelters, foster homes and catteries. These nasty kitty colds are highly contagious — spreading like email spam after one wrong click. Sneezes, shared bowls and even human hands can carry the crud from kitten to kitten until one sniffly kitten becomes a shelter-wide plague.

The most common offenders include bacterial culprits like mycoplasma and chlamydia, as well as viral villains such as feline herpesvirus (FHV-1) and calicivirus (FCV). Some of these URIs can cause lifelong eye drama, especially if corneal damage occurs. Minionless kittens are especially at risk because they have immature immune systems and are often caged in crowded settings. FHV-1 is well known for setting up permanent residence in the eyes, but other pathogens like mycoplasma and FCV can also lead to chronic conditions in cats.

Scientists at the University of California, Davis, wanted to know the best way to treat this microbial mixed bag of ick.

Even cats need protection when the sniffles are going around! Feline upper respiratory infections spread like wildfire in crowded environments. Early treatment helps stop the snot factory. Photo by ShutterStock.

To understand how treatment works, it helps to know how these URIs get into Fluffy in the first place. The microbes enter the cat's body through the mucous membranes and set up shop in the cells lining the nasal passages, mouth and conjunctiva (the clear membrane covering the white part of the eye) and the inside of the eyelids. FHV-1 targets the eyes because it likes the neighborhood. The moist environment gives it a comfortable place to replicate. Then, the virus retreats to the local nerve hub behind the eyes for the rest of Fluffy’s life. It’s like a squatter who lawyered up and gained permanent legal residency, just waiting for some kind of stress so it can flare up.

Herpes can turn on and off forever, but when a cat’s stuck in a nonstop snot cycle, there may be more than one bug playing tag-team in their sinuses.

Before and After: Jeffy the Journalist’s battle with mycoplasma and feline herpesvirus. Left: Severe symptoms. Right: Healthy after proper treatment. A UC Davis study found that doxycycline plus famciclovir helped kittens recover faster and protected their eyes better. Photos by Dusty Rainbolt

It happened to my feline housemate, Bette (and other kitties who later joined our clowder): years of misery and repeated treatment for FHV. Bette was a snot production machine. I’m talking long strings of nasal goo so thick you could’ve caulked a bathtub with them. Once the minion insisted on a snot culture, they discovered Bette was battling 𝘔𝘺𝘤𝘰𝘱𝘭𝘢𝘴𝘮𝘢 𝘧𝘦𝘭𝘪𝘴, not herpes.

Because these kitty colds are such a microbial mixed bag, figuring out the best way to treat them can turn into a real brain-buster. Do you throw the bacterial book at it, or go full-on antivirals? It’s a cellular conundrum.

Mycoplasma doesn’t have a cell wall, so widely used antibiotics like amoxicillin and azithromycin that target walls don’t work on it. After three weeks of doxycycline, Bette’s snot faucet finally shut off.

Turns out mycoplasma is way more common than most folks think, especially in shelters. After the big reveal of Bette’s diagnosis, the human began checking all the chronic snotters. And yup, some of us had the Big M. I, myself, was treated with rounds of doxy after my dramatic rescue as a kitten.

At one AVMA convention, Dr. Michael Lappin of Colorado State University explained that doxycycline should be the go-to treatment in snotting shelter cats because it’s cheap, effective and targets the bug that often gets missed. So if Fluffy’s stuck in an endless URI loop, don’t be afraid to ask your vet about mycoplasma testing — or push for a trial with doxycycline. Sometimes, advocating for your cat’s health means being the squeaky wheel. (BTW — 𝘔𝘺𝘤𝘰𝘱𝘭𝘢𝘴𝘮𝘢 𝘧𝘦𝘭𝘪𝘴 affects the respiratory system, not to be confused with its blood-borne cousins that target red blood cells.)

Nothing says “I’m not thrilled” like a cat getting oral meds. While this method works, veterinarians are moving to the lower-stress “cat burrito” method — wrapping them snugly in a towel. Photo by Deposit Photos

A veterinarian interacts with a kitten during a medical exam. Proper diagnosis and treatment, such as doxycycline with or without famciclovir, can make a major difference in helping shelter and foster kittens recover from upper respiratory infections. Photo by Shutterstock

𝗪𝗵𝗮𝘁 𝗥𝗲𝘀𝗲𝗮𝗿𝗰𝗵𝗲𝗿𝘀 𝗟𝗲𝗮𝗿𝗻𝗲𝗱 𝗔𝗯𝗼𝘂𝘁 𝗧𝗿𝗲𝗮𝘁𝗶𝗻𝗴 𝗨𝗥𝗜𝘀

To figure out the best treatment for kitty colds, a team of scientists from the University of California, Davis, conducted a study of 373 snotty kittens aged 1 to 12 weeks. The study appeared in the November 2024 issue of the 𝘑𝘰𝘶𝘳𝘯𝘢𝘭 𝘰𝘧 𝘍𝘦𝘭𝘪𝘯𝘦 𝘔𝘦𝘥𝘪𝘤𝘪𝘯𝘦 𝘢𝘯𝘥 𝘚𝘶𝘳𝘨𝘦𝘳𝘺.
The kittens were divided into two groups, receiving either doxycycline alone or a cocktail of doxycycline and famciclovir (an antiviral) for 21 days. Everyone also got ofloxacin eye drops and a whole lot of TLC.
Both treatments worked well. A high percentage of kittens in both groups bounced back, their noses drying up and their eyes un-gooping. However, the cocktail kittens with mild sniffles and swollen baby blues bounced back quicker by an average of four to five days. And bonus, they were less likely to develop those nasty corneal issues.
There are a few hold-your-kittens caveats. This study didn’t specifically test famciclovir for safety in tiny patients, although they didn’t see any major red flags. Researchers pointed out the kittens weren’t housed in a typical shelter. They got to chill in foster homes, either solo or in small groups instead of being crammed into cages in a crowded and noisy shelter. Lower stress and less germ-sharing might have played a role in their recovery, too.

𝗖𝗼𝗹𝗱 𝗖𝗮𝘀𝗲 𝗖𝗹𝗼𝘀𝗲𝗱 — 𝗙𝗶𝗻𝗮𝗹 𝗧𝗵𝗼𝘂𝗴𝗵𝘁𝘀
Turns out, a combo of meds might help some of we chronic snotters get better faster and dodge lifelong balloon eyes. So, human minions, if your kitty or foster kitty’s stuck in a snot spiral, speak up. Ask your vet about doxycycline, and maybe read a study or two … You're welcome.

Emily suffered for years with chronic upper respiratory issues before finally being diagnosed with Mycoplasma felis late in life. Many cats like her improve dramatically once they receive the right treatment, such as doxycycline. Photo by Weems S. Hutto

𝗦𝗼𝘂𝗿𝗰𝗲𝘀:

Vernau KM, Kim S, Thomasy SM, et al. Doxycycline with or without famciclovir for infectious ophthalmic and respiratory disease: a prospective, randomized, masked, placebo-controlled trial in 373 kittens. Journal of Feline Medicine and Surgery. 2024;26(11). doi:10.1177/1098612X241278413. https://journals.sagepub.com/doi/10.1177/1098612X241278413

Lappin, Michael R. “Treatment of Mycoplasma spp. infections in cats.” Veterinary Practice, June 1, 2010. (No longer available online.)

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