I’m writing this from first-person experience to help others who may encounter calicivirus as a pet owner or foster home. I’m not a vet, vet-tech, or any other form of expert. I’m a foster mom … we ran head-first into this challenge with our foster kittens. I believe four vets (in 3 separate practices) saw these cats and said that it was calicivirus – but it is not conclusive since I didn’t pay to have the lab test done (there was no benefit or change in how this would have been treated).
I have never paid attention to what was in the annual shots my cats got. This time fostering, I learned that one part of the shot is for calicivirus. It is a common upper respiratory infection that many cats have been exposed to.
What Is Calicivirus?
Calicivirus (FCV) is a virus (duh, I know!). It is contagious from one cat to another and can be caught from direct contact (licking, sneezing, playing together etc) or secondary contact (sharing a space, sharing food bowls, litter). There are a number of different strains of this – and it is constantly mutating. It makes it very hard to contain. It tends to surface in highly populated areas of cats – shelters or homes with a high density of cats.
First of all, calicivirus is not transferable from one species to another (it’s not zoonotic) – so a sick cat cannot affect you or your dog. (There are unrelated strains of calicivirus which manifest in humans – one is known as the Norwalk virus.) However, it is very easily communicable from one cat to another. A cat is contagious as soon as the virus takes hold- before there are visible symptoms. This was proven in our home. The cat is also potentially contagious for weeks after the infection as the virus is ‘shed’ from their bodies. Some cats who are exposed to the virus are carriers of the virus for their whole lives and continue to ‘shed’ the virus.
The virus does not have a ‘cure’. Once your cat is exposed to it and develops symptoms, she must go though the virus on her own. The vet can test for the virus (blood test) or visually confirm that it is calicivirus (usually by mouth ulcers), and treat the secondary symptoms such as bacterial infections or pneumonia with antibiotics. The antibiotics don’t solve the virus, but only treat the infections resulting from it.
Calicivirus does not usually kill the kitty, but it can. Some strains can be mild and barely noticeable. Kittens are the most at risk of catching this virus. The most dangerous instances are when it attacks a young kitten who’s immune system is low, and when it attacks a cat who’s immune system is already compromised from another type of illness. However, there is at least one strain that is very, very contagious, attacks adult cats the hardest, and has a higher-than-normal mortality rate (as high as 60%).
I am still not sure how our foster kittens caught this virus. They could have caught it from the dirty and crowded conditions they came from (17+ cats in a hoarder’s apartment). It might have even been passed to them from their mother. However, if this is the case, then the symptoms and virus should have manifested sooner than 6 weeks after they arrived at my home and were quarantined. Additionally, the other cats rescued from this situation have not come down with the virus. The second potential exposure point was the vet’s office where the first 2 kittens went for their shots and surgery. Although this is a clean establishment, a close-proximity sneeze by one sick cat could be all it took. The symptoms manifested in the first kitten about 4-5 days later.
How Can You Tell If It’s Calicivirus?
The signs of the strain we encountered were stopping of eating and drinking, a fever, extreme lethargy, sores on the tip of the nose (2 kittens) and in the mouth (3 kittens). There was no sneezing, runny noses, or weepy eyes during the infection which are also ‘typical symptoms’.
When we first noticed a sick kitten, we assumed that the neuter surgery was the cause since it was about 3 days post-op and the symptoms matched. We syringe fed the kitten pedialyte and then ‘slurry’ (blended pedialyte with a pate-style cat food). Since there was no improvement in 48 hours, he went to the vet. The kitten was force-fed, given subcutaneous fluids, started on amoxicillin antibiotic at the vet’s office. He returned home that evening (12-hrs in hospital) in hopes that a familiar environment would help him recover. The vet suspected a virus. He was put on a 10-day antibiotic cycle – dosing every 12 hours. Although he was weakened and had lost weight, the kitten recovered slowly over the next 5 days. Regular syringe feeding and pedialyte was needed until he began eating again. A few days later he was fully recovered and eating very healthily: it was approximately 8 days from the onset to his recovery and eating sufficiently on his own.
During the recovery period, the other kittens also began to come down with this virus. We began antibiotics at the first signs of the virus. This time the vet noticed some visual cues to indicate that this was calicivirus. All kittens were given the same treatment as the first: amoxicillin antibiotics administered orally in liquid form. All kittens were syringe fed slurry multiple times a day to avoid anorexia.
The kittens who had the antibiotics at first visual cues of the virus had less pronounced symptoms, less ‘down days’, and faster recovery periods. Two kittens developed lesions on their noses. The first kitten developed a few small scabs on his body (about 5) as he was recovering. About 3 kittens had ulcerated gums or tongues, which I believe were the symptoms that vet used for diagnosis.
When the kittens began showing signs of the virus, they were kept in a quarantined space. However prior to them showing signs, they were allowed into our front room where they met their adopters. This space is shared space in that for some hours each day the kittens were in this space with the door closed. When the kittens were not in the space, my own cats were allowed to walk in and use the space at their leisure.
As the kittens were recovering, my own three cats displayed symptoms of this strain. The illness was incredibly more pronounced in my two older cats:
Cat 1 (Healthy, 1 year old – inoculated with all kitten boosters and her annual shots 1 month prior to infection) Showed some lethargy and lack of appetite. It lasted a couple of days and then she was back to normal. Her contact was direct – she played with the kittens when they returned from their vet appointment. It is to be noted that she is in direct daily contact with cats 2 and 3.
Cat 2 (Healthy, approx 8 years old – inoculated regularly and 1 month prior to infection) This cat had no direct contact with the kittens– she infrequently uses the one room of shared space. She began showing lack of appetite and weakness. She then stopped eating and developed lethargy, some sores in her mouth, a red raw nose, and excess salivation. Multiple types of food were tried to encourage eating – warmed, wet, dry, kitten and vet formulas (such as a/d, i/d, recovery) with no results of any eating. She was given amoxicillin every 12 hours for 10 days beginning early in the onset of the visible symptoms. She slept more but remained mobile to the litter. Due to this cat’s strong aversion to pill-taking, she was changed to liquid amoxicillin antibiotic part way through treatment. She was given pain-killer once a day. On day 8 she developed a large sore on her front leg which caused limping. Her nose was crusting over slowly – topical antiseptic cream was used 1x a day on her nose. Almost a month after first symptoms, her nose has only one pink spot of healing, she has been eating on her own for almost 2 weeks, and her leg sore dried but no fur returned for a couple of months.
Cat 3 (Healthy overall, 16.5 years old – inoculated regularly her whole life but 1 month late on her annual inoculation, first diagnosed with moderately reduced kidney levels and mild hyper-thyroidism 1-month prior to infection. Not on any medications. The only illness this cat has ever had was 3x bladder crystals when she was between 3-6yrs old) This cat was not in direct contact with the kittens, but used the one room of shared space. She likely tried to eat some of the kitten’s food from their bowl. Her symptoms began with lack of appetite, fever, and lethargy. Multiple types of food were tried to encourage eating – warmed, wet, dry, kitten and vet formulas (such as a/d, i/d, recovery) with no results of any eating. However symptoms progressed and became severe to include – no eating or drinking for 1.5 weeks, large weeping sores on her mouth, gums and tongue, bleeding sores, her face became significantly swollen, a red raw nose, sores between mouth and nose, difficulty breathing, wheezing, sneezing, excessive drooling, and limping. She slept almost 24 hours a day and was not mobile even to the litter. On day 9 of the visible sores … improvements have been seen in the reduction of facial swelling, she was almost able to use her tongue and was visibly trying to drink water without much success; sores still present but subsiding. By day 11 she began to attempt to eat wet cat food – with difficulty due to breathing problems and the continued existence of large sores in the mouth and on tongue. She became more alert and beginning to gain some mobility after 12 days. Despite some stomach upset, we decided to keep her on the antibiotics beyond the 10-day course to ward off any secondary infections still lingering or emerging. The antibiotics were stopped at approximately day 14 to control the antibiotic-induced diarrhea. At this point the resolution of her sores seemed to slow down, but she slowly, steadily improved. By week 3 she was able to eat on her own but avoided all dry foods (I suspect the existence of throat and back-of-mouth sores still present) – even tiny-sized kitten formulas. Strong smelling food (water-packed low-sodium tuna) was the first food she was drawn to try eating. She was able to drink normally late in week 3. Weight loss has been significant (more than 1/3 of her weight) and this will need to be addressed to aid her full recovery. Her visual symptoms were worse than any I’ve seen (on the web) as she was unrecognizable, bloodied constantly, and the sores were very large and prohibited her tongue and mouth movement. I was too traumatized to photograph this as I was not convinced she would survive.
We needed to give our two very ill cats round-the-clock attention with liquids, slurry-food, medications etc for two full weeks. If this is not possible, a cat as sick as ours would have needed to be hospitalized and had IV and forced feedings for over a week. If it’s possible to give the cat subcutaneous fluids at home, I’d strongly suggest this. It is my opinion that I let her become too dehydrated despite feeding her syringe-fulls of pedialyte several times during every day.
The cost of visiting the vet for a brief physical exam for our two cats and prescriptions for antibiotics, one subcutaneous fluids application, was about $400 (not including medications). The exams showed nothing less than 24 hours before the full onset of the illness: I had taken them in because I’d noticed both older cats were eating less and were more lethargic (this would have been easy to miss but I was watching them). Unfortunately, I could not simply get the required antibiotics without the vet-consultation even though I knew what I was dealing with after the kittens’ illness and symptoms. I don’t have the vet costs for the kittens, since the rescue paid for that.
I suspect that this strain is deadly because the adult, well-inoculated cats became significantly more severely sick and for a longer duration than the kittens. Transmission was 100% even for those cats not in direct contact with the affected kittens. It is suspected that we encountered a more virulent strain. I didn’t get my cats tested for what this is and neither did the rescue – the blood tests would have cost more and they would not have aided with the resolution. The blood-test would have been more academic than helpful. It is also noted that 2/3 vets presented with these cats were not able to identify/detect the virus while it was showing as fever, lethargy, and diminished (or stopped) eating and drinking. Transmission is easier in these circumstances since there is no warning to quarantine early enough to make any difference.
The virus is virtually impossible to ‘clean’ out of a space – it doesn’t die from most cleaning solutions. For 28+ days after the last cat has recovered from all viral signs, our home must be considered contaminated and off limits to cats and those who have cats, to be safe. The virus can apparently live in an environment for that period of time – longer if it’s a cold environment.
As a precaution, we are not having any cats in our home for a period of 3 months post infection. Carpets are being cleaned, wood floors are being steamed multiple times, and the hepa-filter on our furnace (hvac system) has been changed. The hepafilter for viruses is helpful in this case.
This post on my blog is not intended to create a managed public forum of Q&A, advice, or individual situations. It is meant as a real and detailed account that I hope helps you. There are vet sites and online groups that offer Q&A boards. As always a vet is the best source of advice. I won’t be publishing any more advice inquiries or responses sent to me from this page on my blog. Thanks! Best wishes to you and your kitties!