Wagner DC, Kass PH, Hurley KF. Cage size, movement in and out of housing during daily care, and other environmental and population health risk factors for feline upper respiratory disease in nine North American animal shelters. PLoS ONE13(1):e019040.
Diagnosis, treatment, and management of upper respiratory tract infections (URIs) in shelters can consume up to one-third of a shelter’s available feline care resources. URIs are a leading cause of euthanasia of individual cats as well as depopulation of shelters, and they reduce cats’ chances of adoption. These infections, which often manifest in cats within one to two weeks of shelter admission, frequently begin with the common viral agents, feline herpesvirus-1 (FHV-1) or feline calicivirus. Other pathogens that may be involved are Mycoplasma spp., Chlamydophila felis, and Bordetella bronchiseptica. Cats are often subclinically infected carriers of one or more of these pathogens; recrudescence of these infections with emergence of clinical signs of URI due to the stress of shelter admission is common, and well-documented in the literature.
While strict isolation procedures can help prevent the spread of infection, support of a newly admitted shelter cat’s behavioral health with environmental enrichment and social interaction with other cats and with humans is also essential. These goals appear mutually exclusive, but this study of cats housed in nine shelters in various communities in the United States and Canada has demonstrated that high rates of feline URI are not an inevitability in every shelter, even though periodic introduction of upper respiratory pathogens into these environments undoubtedly occurs. In particular, the care and housing offered to cats within the first week of admission to the shelter has a significant impact on the rate of URI.
Participating shelters entered data into an online URI database on a daily basis, including information regarding the number of adult cats present in the shelter with or without clinical signs of URI, length of each cat’s stay at the shelter, and environmental and management information such as cage size, hiding places, vaccinations, and disinfection protocols. Parenteral modified live vaccination for feline calicivirus, herpesvirus, and panleukopenia was given to all cats upon intake at all participating shelters, and all of these shelters fed a consistent diet daily rather than using a variety of donated foods.
One limitation of the study is that no standard definition of URI was used among all shelters; some shelters considered any single clinical sign of URI to be a URI, while others had a more strict definition of URI, requiring two or more clinical signs of URI or systemic illness for the cat to be classified as having a URI. Surprisingly, the shelter with the lowest reported URI rate had the most inclusive diagnostic criteria (one clinical sign sufficient), while those shelters with higher URI rates had stricter, less inclusive criteria for identifying URI.
Feral cats were not included in the study, as were cats who had URIs upon shelter admission or who developed URIs within 1-2 days of intake; these were considered pre-existing infections. PCR testing for upper respiratory disease pathogens was conducted at five of the participating shelters. In each of the five shelters participating in PCR testing, oropharyngeal and conjunctival swabs were collected from 20 apparently healthy newly admitted cats within 24 hours of admission and then every three months. There were no significant effects of the prevalence of URI pathogens as determined by PCR testing on shelter URI incidence rates.
The total number of animals included in the study was 18,373, representing 210,987 cat days at risk for URI and 31,924 actual cat days with URI. The study lasted an entire year, from August 1, 2008 through July 31, 2009. During this period two shelters had very low URI incidence rates; one had less than 3 URI cases/1000 cat days at risk, and another had less than 11 cases/1000 cat days at risk. In other cases URI incidence varied from high to low at different times of the year, while three shelters had URI incidence rates >15 cases/1000 cat days at risk for over half of the study year. Geographically, the shelters were located in various climatic zones from Canada to southern California. An annual graph of URI incidence rates showed peaks in one to several months for each of the shelters, but the peak months varied by shelter. The shelters were not identified by name or location, but by a number only, so it is impossible to correlate geographic location with peak months for URIs.
Housing design and layout had a very significant effect on the incidence of URI in adult cats. In many shelters cat kennels offer about 4 square feet of floor space. Those shelters providing cage or enclosure floor space of > 8 square feet had a lower incidence of URI than those offering cage floor space of less than 6 square feet, or floor space between 6-8 square feet. Two or fewer housing moves in the first week of shelter stay was also significantly associated with lower URI incidence. In conjunction with this, the use of double compartment kennels that allowed the cat to stay on one side of the cage while the other side was cleaned, and also facilitated placement of the litter box in a separate space from food, water, and bedding, was associated with reduced incidence of URI. The authors recommend that shelters replace any current small single compartment kennels (often used to house cats upon intake) with large double-compartment kennels or larger walk-in enclosures and provide these spaces for all cats, including those who are newly admitted.
No increased risk of URI was noted in shelters that housed adult cats and juveniles in the same area compared to those that kept adults and juveniles in separate housing areas. This would suggest that recrudescence of latent infection and stress in the adult cats play a more important role in emergence of URI in shelters than exposure to the increased pathogen shedding that is likely with kittens. Additional studies of co-housed adults and juveniles would be useful in determining whether separate housing should be provided for kittens to protect them from subclinically infected adults shedding pathogens against which the kittens may have not developed immunity.
Increased incidence rate of URI was surprisingly associated with the provision of hiding places and also with the use of intranasal URI vaccines. In previous studies, availability of a hiding place has been found to be beneficial in reducing stress levels in cats. Given the fact that five of the six shelters that provided a solid hiding structure confined the cats in small cages with floor areas of < 6 square feet, the authors surmise that this structure, along with the litterbox, food, and water dishes, consumed so much of the limited floor space in the kennel that the cat’s stress level was increased. If kennel floor space cannot be increased in a shelter, alternative ways to provide a perch or hiding space by providing a raised bed and/or a partial towel drape over the kennel door to conserve floor space, should be considered.
Four of the nine shelters reported using modified live intranasal FVRC (feline viral rhinotracheitis and calicivirus) vaccines on all cats at admission. Intranasal vaccines are used by some shelters on intake as they tend to induce more rapid immunity than subcutaneous vaccines and will also elicit a local mucosal immune response. However, clinical trials have shown that these vaccines can be associated with mild clinical signs of URI in up to 30% of vaccinates. It is possible that such vaccine-associated clinical signs were attributed to URI by participating shelters and therefore added artifactually to a shelter’s reported URI incidence rate.
This study also demonstrated that URI incidence can be controlled regardless of shelter size. The intake number was not associated with increased risk of URI in any of the shelters studied. The range of intake for the nine shelters was 700-4500 cats annually.
Results of this study offer a recommendation for practical steps a shelter can take to reduce the incidence of URI amongst its feline population, especially newly admitted cats. This includes remodeling or replacing kennels so they provide each cat over 8 square feet of floor space and double-compartment housing or larger enclosures, and minimizing or eliminating the number of episodes in which cats must be moved within the shelter in order to clean their kennels, for assessment and treatment, or to rotate them into new areas of the shelter, especially in the first two weeks of residence. While there will inevitably be significant costs in money and labor for some shelters to remodel in this way, the benefits resulting from these changes for the cats, shelter staff and resources, and the adopting public is likely to more than compensate for these investments. [PJS]