Foster homes are the best way to get pets out of a stressful shelter environment and expand a community’s capacity to care for its homeless pets. How can foster homes protect their foster pets and their own dogs and cats, too, from canine parvovirus and feline panleukopenia?

Guest post by Dr. Kate Hurley
Director, Koret Shelter Medicine Program, UC Davis

As shelters utilize foster homes more extensively, it’s inevitable that from time to time a foster home will become contaminated with a serious and hard to eliminate pathogen such as parvovirus or panleukopenia.

The question then arises, what to do about that home? Do you err on the “safe side” and keep it closed for months waiting for the risk to pass? Or re-open the home sooner and worry about exposing another vulnerable puppy or kitten to serious illness?

Recently, this question arose on the email list serve for the Association of Shelter Veterinarians. In this case, the question was in regards to opening up foster homes after parvovirus exposure, but the same answer would apply to kittens and panleukopenia.

In a dark, moist environment, parvo can live for years, but getting rid of parvovirus in a reasonably tidy home is not as daunting as it might seem. Just cleaning the environment thoroughly helps a lot; if you remove the virus by cleaning, you don’t have to worry about killing it with a disinfectant.

There are also disinfectants available these days that can be used on virtually any surface. Accelerated hydrogen peroxide is reliably parvocidal and can be applied via carpet cleaners or by spray on a variety of surfaces in a home (test a small area first on carpet and upholstery, but I haven’t run into problems and use it all over my own home).

Trifectant/Virkon (potassium peroxymonosulfate) can also be applied this way.

Either of these two disinfectants is also a good choice for decontaminating soiled vehicles and may even help knock back the dose in outdoor areas; both have relatively good activity in the face of organic matter. Although there is no practical way to verify that a foster home is truly decontaminated, it’s likely that thorough cleaning and disinfection with a parvocidal product will markedly reduce the amount of viable pathogen present.

Remember it is all about dose effect and risk/benefit analysis. Although parvo and panleukopenia are extremely durable, good cleaning and disinfection will reduce the dose substantially. This is even more likely if the contamination was mostly confined to a limited area, or if heavily contaminated areas are relatively amenable to disinfection (smooth, uncluttered surfaces).

Confining any new fosters away from heavily contaminated areas will reduce the dose further. For instance, fosters can be confined in the bathroom, climate controlled garage or other area that lends itself to disinfection. Allowing fosters to roam freely about the house is certainly not ideal from a disease control perspective, but in my experience it is often what happens, especially as they get older and it becomes difficult to meet their needs for play and socialization in the confines of a bathroom.

In that case, perhaps at least heavily contaminated areas such as a bedroom where a sick animal was housed can be closed off to lower the risk.

Also be sure fosters are kept away from any dark, moist spots such as shady, damp corners of the yard that may have been contaminated.

Animals in good health are able to withstand some dose, even absent vaccine protection. Many kittens and puppies will not have maternal antibodies to panleuk/parvo and therefore will be protected by the first vaccine they receive within a few days. Put that all together and you have some risk, but probably a very low risk in many cases.

Now balance that with the risk of keeping parvo-exposed foster homes closed for extended periods. For a shelter that has an abundance of foster homes, this is also a small risk, and being very cautious about re-opening foster homes is a fine choice. Meanwhile, maybe these homes can be re-purposed for animals over 5 months old that have been vaccinated for at least a week beforehand -– animals that need work on behavior, time to recover from respiratory disease, or just a break from the shelter, to name a few.

But for a shelter that sometimes runs short of foster homes, does keeping a parvo/panleuk exposed homes closed for long periods mean vulnerable youngsters stay in the shelter longer? Unless the shelter has truly excellent housing and disease control, it may well be that the shelter is a higher risk than a cleaned and sanitized foster home that was exposed to panleuk/parvo.

Certainly, if kittens/puppies are being euthanized for lack of foster care, a small risk of panleuk/parvo lingering in a foster home might well be a reasonable risk to take.

Do be sure and have a conversation with the foster parents before sending any more youngsters their way: first, check that they really were able to do a good job of cleaning (in a very messy house or hoarding type house this will probably not be possible) and second, make sure they understand the risk/benefit balance and know that even with the small risk of environmental contamination their home is the safest place you can find for youngsters.

Also of interest:

Controlling Parvo (Page 4): An oldie but still a goodie. The only update is the widespread availability now of accelerated hydrogen peroxide, a great addition to our lineup of reliably parvocidal disinfectants.