When one animal from a population is diagnosed with FPV, the question arises: what do you do about others in the environment? Are they all likely to get sick? Will widespread quarantine or depopulation be necessary? Or is it okay to simply carry on business as usual, or somewhere in between? The answers to these questions are dependent on several factors.
Not all exposed cats will become infected. Due to varying levels of maternal antibody, it is not even uncommon for only some members of a litter to develop disease. The risk of infection depends on the animal’s individual immune and vaccination status, the overall cleanliness of the environment and the level of proximity between the exposed and infected animal.
The most important factor in disease risk is vaccination: a “fully” vaccinated cat over 5 months old is at very low risk of infection (i.e. vaccinated at least 3 days prior to exposure, keeping in mind that shedding may occur up to 3 days before clinical signs become apparent). However, even incompletely vaccinated animals can survive an exposure if health is good and dose is low.
Serology may be a useful tool to identify cats at low risk and limit the number of cats requiring quarantine. Serological tests for panleukopenia are available from several laboratories. Not all laboratories have been validated; consult with your local veterinary school.
There is a panleukopenia titer kit (VacciCheck ImmunoCombTM by Biogal) available for in-house use. One study found the sensitivity and specificity to be up to 89% (meaning that there is a ~ 1 in 10 risk of false positive results [calling a cat protected when really not]). Combined with rectal temperature and careful physical exam revealing no abnormalities, healthy adult cats with a protective IgG titer at the time of exposure can be considered at very low risk – moving these cats along as usual, with no quarantine, is a reasonable choice.
If a single case occurs in an area where all animals have been vaccinated and environmental spread risk is deemed low based on the above-listed factors, quarantine or depopulation may not be necessary. If spread is observed or few of the above precautions are in place, the whole ward or even the whole shelter may need to be considered at risk/exposed. An intermediate response is to assess risk for immediately adjacent cages only – this is logical only if exposure is likely much lower in cats elsewhere in the ward.
Cats that are both meaningfully exposed and at-risk must be strictly quarantined to prevent continued spread of disease. If a full ward has been exposed and all cats are considered at risk, it may be most efficient to simply shut down that ward to new admissions for the quarantine period. If exposed/at-risk cats are scattered throughout the building, gather them together into an area of the shelter that can be easily cleaned, allows individual cat monitoring (one litter or cat per cage), and can be effectively segregated from the rest of the building.
If there is no separate place to quarantine cats within the shelter, consider closing the shelter to new intakes during the quarantine period and quarantining cats on site. It may be easier to set up an off-site location or short term agreement with a local veterinary facility to permit emergency admissions to continue during this time. Well-informed foster homes with the ability to adequately monitor and segregate cats may also be an option, especially when the risk of illness is considered relatively low.Any area where cats are quarantined must be able to be thoroughly cleaned and disinfected - no carpet, furniture, wood, grass, etc. Foster parents should be counseled carefully about the need to prevent contamination of their homes, as well as the grave prognosis should the cats become ill.
For kittens and cats that were not vaccinated prior to the time of exposure, vaccination after exposure will likely have little benefit. However, vaccination will not harm the kittens, and vaccine schedules should be maintained as usual in exposed kittens that are not ill.
Passive protection from serum transfusion has been shown in puppies exposed to canine parvovirus. Therefore, it may be that in exposed, unvaccinated kittens, 2 ml of serum from an immune cat given SC or intraperitoneal soon after exposure may provide some protection4. Serum donors should be cats from a known source and free of infectious disease; ideally, serum donors should be blood typed. If not using serum from known specific pathogen free cats, the risk of transmitting FeLV from cats with regressive infections should be balanced against the risk of panleukopenia infection. If serum transfusion is performed, vaccination should be delayed by 2-4 weeks, and continued 2-4 weeks longer than usual.