Kitty Cold – Feline Herpes Virus (FHV): This Much I Know

I’m writing this from first-person experience with my own cats to help others who may encounter FHV as a pet owner or foster home. I’m not a vet, vet-tech, or any other form of expert. We encountered this challenge with our newly adopted shelter-rescue kitten – and soon our own healthy cat who had never had kitty cold was sick. You are getting my notes that helped me decide what steps to take.

I will be amending and updating this over the next few days… as I learn more and we work through this in my home.

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What Is It?

Kitty colds are common viruses and spread very quickly in any place that has a large number of cats – pet shows, shelters, homes with a high density of cats. Like with kids, if one gets it, it’s very likely that many will. Its transmission is fast and it’s airborne. Picture a kid sneezing in a daycare centre – and how those particulates spread, and then the kids closest to that sneeze spread it by their hands onto the toys… and so on. It’s really the same with our fur kids.

A kitty cold or ‘cat flu’ can be one of a group of viruses – feline herpes and calicivirus being the most common.  These are different viruses – and their symptoms have overlap, but there are some that are distinct (like the lameness from calicivirus). Not only are there different viruses, but they have different durations, time they keep shedding from the kitty (how long the kitty is contagious to others), and cleaning options.

Given these differences, do you need to know which one you are dealing with? Yes – and no. In my experience, many vets can’t tell one from the other in the earlier stages. And with viruses, it’s best to catch them early and address them quickly so the kitty will have less ‘down days’. If a virus is detected, the vet may decide to let the kitty beat it on their own (if there are no dangerous symptoms) or to put them on a general antibiotic. That process seems to be the same no matter which of the viruses or URIs you encounter. Antibiotics don’t cure the virus, but instead address the secondary infections which result. These range from lung/breathing issues and pneumonia, to nasal infections (with coloured discharges), to ocular problems.

Feline Herpes aka Cat Cold

Feline herpes virus (FHV or FHV-1) is the virus that causes feline viral rhinotracheitis or feline viral rhinopneumonitis (FVR). The first (FHV) is the virus, and the second (FVR) is the resulting illness. About 50% of all cat-colds are this virus which has an incubation of 2-7 days. This can be as mild as a few sneezes and watery eyes to the more dangerous symptoms – even death from pneumonia in kittens. Most cats come into contact with this virus at some point of their lives: it’s transmitted by direct contact. If their immune systems are strong they will avoid it but the more direct contact, the more likely they are to catch it. Once a cat catches FHV, they carry it in their systems for life and can shed the virus in times of stress and change (aka become contagious). Some cats develop chronic colds – and repeatedly get the symptoms every few months.

Since our recently adopted shelter-kitten had already been diagnosed with rhinotracheitis (or contagious feline viral rhinotracheitis / feline influenza), that is what I’m addressing here. This kitty cold is caused by a herpes virus (just like a different herpes-family virus causes colds and cold-sores in humans) that is not zoonotic. That means that while it’s extremely contagious between cats, you or your dog won’t catch it.


Once the cat has FVR, her body must work through the virus. It can take 4-9 days according to some accounts and longer if there complications or if there is reinfection. Symptoms can be frequent sneezing, discharge from mucus membranes (eyes or nose), drooling, conjunctivitis, congestion, fever, lack of eating, squinting and other eye irritation including eye ulceration.

If symptoms are severe – if there is coughing or ‘hiccuping’ or any sounds of congested lungs – then a vet visit for antibiotics is a good call. Antibiotics help resolve the illness faster because it addresses the secondary infections.

Mild teary eyes or mild crusts and common and we had this with our Rascals kittens. I received a recipe from the rescue: one cup boiled (and cooled to warm) water with one teaspoon of epsom salts. Gently cleaning the eye area with this solution and a very clean, soft, non-shedding towel or handkerchief 2x a day helps to get rid of the crusting and helps resolve the issue.

Steam for congestion is very helpful. We’ve used this for our cat with severe calicivirus and now with Cat 2 with rhinotracheitis. In a closed bathroom (the smaller the better) run the shower on hottest and let the room fill with steam. Turn off the water and leave the cat there until the steam dissipates -allowing her to breath it in. It helps to clear their nasal passages. If your cat is quarantined in one room, then a humidifier will help.

Hydration is extremely important – so any way you can encourage your cat to drink liquids is great. Sneaky ways are tuna or salmon water (low-sodium/ water packed!) since strong smelling food can lure them to drink. If that fails, feed water or pedialyte solution by syringe orally a number of times a day. If you are skilled, you can administer subcutaneous fluids – if not this will cost a little but it can be done by your vet.

Ceasing eating is another symptom and while this is not as dangerous to the kitty as lack of hydration, you wouldn’t want this to continue for more than a day or so. Offer soft, easily eaten, strong scented foods to try to entice them. For cats who stop eating entirely or seem unable to, consider feeding them a slurry (blended milkshake) of high-nutrition pate cat food with pedialyte. We have NutriCal at home – since it gives nutrition in a paste that can be simple put into your cat’s mouth or on her paw (she’d lick it off to clean herself).

Our Cats

When Cat 1 caught it, he was a tiny kitten… just about 6 weeks old. His chart shows rhinotracheitis with a grade 3 cardio elevation. He was diagnosed and treated with azithromycin for seven days – a broad spectrum antibiotic that helps resolve bacterial infections resulting from this virus and others. (With calicivirus our cats were treated with amoxicillin) There is no ‘cure’ for the virus itself and the kitty has to get through that on his or her own. Our kitty’s chart showed that he recovered 2-3 weeks before we met him.

Once the kitty has had this virus, it can return at times of stress, change, illness or immune suppression. I think that environmental changes (traveling by car for a few hours, sitting in a pet store, meeting other kittens who also may have had this) probably brought on a relapse with our kitten.

When we met Cat 1 in the pet store, he was sneezing. He was being given lysine daily at the store. Lysine is an amino acid and meant to be an immune booster for the affected cats – to help them get over the kitty-cold faster. Once we brought him home, we missed the first day, but began lysine on the second day. For a kitten under 6 months, 250mg twice a day is a recommended dose. For a cat 500mg once a day is good. There are a number of formulations – ones you can get from the vet, some in the pet store, and the human version. This medication is one where you can use the human pill divided up for a cat. Some of the pet-store formulas have other ingredients that assist with cat health. More recent tests with cats (rather than lab cat cells) have not shown that lysine has any results in aiding recovery. Since we had already purchased it and begun dosing, I opted to continue though I don’t think this is particularly effective.

Cat 2 came down with sneezing symptoms about 2 days after direct contact was allowed between the two cats. She had been getting lysine for 5 days before she developed the symptoms. In our case, neither cat showed watery eyes or nasal discharge other than the sneeze. Cat 2 soon began other symptoms – lethargy, lack of zeal/less alert, fever (I think), slowed eating, more sneezing, and some sounds of congestion.

Cat 3 avoided Cat 1 and has not shown signs of sneezing or the cold a week after  Cat 2 developed symptoms.

Cats 2 and 3 are regularly inoculated – we have recently gone to a bi-annual cycle of FVRCP vaccine shot which protects against feline viral rhinotracheitis, calicivirus, and panleukopenia. Frustrated with the lack of prevention by the vaccine, I read that the FVR shot does not prevent the virus at all but does make the symptoms less severe. FVR is mutating – as human cold and flu viruses do – so no one vaccine will be fully effective.

Home Solutions

While this virus does not live long outside the body of hosts (18 hrs I believe), it is easily transmitted though contact from eye, nose and mouth secretions. This can be through shared water or food bowls, litters, toys, cat beds, clothes etc. as well as being sneezed on.

Clean freaks, get your gear on! This is a virus that can be cleaned out of the space with soap and water solutions. I have just steam cleaned the floors, washed the cat soft toys and blankets, washed the throws on the couch, and disinfected the cat food bowls. Look at your space through your cats’ use and think of where the sneeze/secretion radius is – what items become carriers?

Since bonded cats co-clean, share bowls and litters, and often share toys and soft bedding, treating both cats together might be optimal to avoid them passing from one to the other and back again. Addressing the space and the inanimate virus carriers is key – because that is the most prevalent transmission method.

Other things that can help in your home would be to run the hvac on a hepafilter, vacuuming with a hepa (since most hepa’s trap virus size particles), and creating a quiet restful environment for your ill cat to help her recover.




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