This blog summarizes the findings of an important new study on feline URI in shelters. The study investigated the incidence of URI at nine shelters and analyzed the factors associated with incidence.
- URI rates in cats can be substantially reduced by using simple strategies.
- The most significant protective factors were providing > 8 square feet of floor space and limiting the number of moves in the first week. Double compartment housing is recommended to minimize stress.
- Based on the discussion, it is important to ensure that the floor space is actually available to the cat, and adding hiding boxes to smaller cages could be detrimental. Curtains or raised beds should be considered for small cages. (This is speculative, but makes sense.)
URI rates: Nearly 50 times difference between lowest and highest
The URI rate was expressed as an annual average rate, calculated by dividing the number of cases by cat days at risk. There were large differences between shelters, with rates ranging from 0.7 to 33.5, with an average of 14.8.
The main limitation was that there was no universal case definition for URI between the participating shelters, which could have led to overestimating rates in some and underestimating in others.
PCRs were performed at intake on 329 cats from 5 shelters. The most common pathogens were Mycoplasma felis (average 27%) and feline herpesvirus (average 25%), followed by calicivirus at 14%. Chlamydophila was uncommon (average < 1%), and Bordetella also quite uncommon (average 4%).
These numbers did not correlate with URI rates, which were “independent of the frequency of pathogen carriage in cats at intake”. The study did not look at transmission of pathogens during the cats’ stay in the shelter or what pathogens, or mix of pathogens, were associated with active disease. However, this is another useful reminder to remain cognisant of the triangle of host, pathogen and environment.
What provided significant protection against URI?
- Providing more than 8 square feet of floor space was highly protective. Cage size between 6 and 8 square feet did not provide any protection.
- Limiting the number of moves in the first week to two or fewer also provided highly significant protection. Previous studies have also shown an association between multiple moves and URI.
What didn’t make a difference to URI rates?
- Cat intake numbers
- Mixed-age housing. Recommendations up to now have been to keep adults and kittens separate to protect kittens from subclinical shedding. (A counter-argument is that concentrating kittens together could actually increase their risk of disease, given that they are more likely to develop clinical signs and shed large numbers of organisms.) It’s difficult to draw any conclusions about housing kittens from this study, though, because it only looked at URI in adults.
What made things worse?
- Providing hiding spaces in intake housing was associated with significantly higher URI rates. This was a surprising finding, considering the documented benefits of hiding places. One possible explanation for the finding was that in 5/6 shelters that provided hiding places, the cages were < 6 square feet, so the hiding places further reduced the available space and this could have actually increased stress. It’s important, therefore, to be aware of how much actual floor space is available to the cat. (My experience at our shelter is that the more an animal is loved, the more stuff people want to put in the cage!)
- Intranasal vaccines were also associated with increased URI rates. The previous literature on intranasal vaccines in shelters has been unimpressive, reporting variable efficacy to no benefit, with up to 30% of cats showing mild clinical signs post-IN vaccine in one study.
- Wagner DC et al. 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 One 2018; 1-15. Full text: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0190140