In my first real shelter veterinarian job, the cats in the shelter got upper respiratory disease (URD, also called URI) like clockwork. With complete predictability, they were sick on day 5 after intake. At that time, the legal stray holding period was 7 days (okay to leave on day 8), so almost everyone took a tour of the isolation ward before they left. And the isolation ward was ALWAYS full.
This meant that what often started as a mild routine cat cold frequently progressed to a severe case requiring intensive supportive care to keep them alive. And in those difficult seasons when there were just too many cats to care for, some didn’t make it out of isolation alive. It was a vicious cycle contributing to prolonged stays in care and shelter crowding. Staff were exhausted physically and emotionally. It was a really difficult experience for me as a new shelter veterinarian. I knew how to properly treat a cat with upper respiratory disease, but the inability to prevent new cases combined with the sheer number of cats who became ill created a situation that made it impossible for our team to provide the best possible outcomes for all of those cats, many of whom arrived at the shelter perfectly healthy.
We didn’t break out of this vicious cycle with better treatment plans or by asking our team to work longer hours. We made a lot of big management changes as a team in my first few months, but the one change that truly pulled us out of the URI spiral was installing portals in our single-compartment cat cages. Now, each individual housing unit consisted of two compartments, and seemingly overnight, cats stopped breaking with respiratory disease on day 5. We could now provide individualized care for all of the cats in our care, including extensive treatment plans for those sick cats who really needed it. Things weren’t suddenly perfect, but they were a heck of a lot better.
Feline URI and Stress: Understanding the Pattern
The predictable pattern of cats getting URI on day 5 at that shelter is a pattern that a lot of shelters have experienced. It even has a name: Feline Endemic Upper Respiratory Infection. Technically, it’s caused by feline herpesvirus, but more specifically, it’s the combination of cats experiencing significant stress with herpesvirus that ultimately leads to the feline respiratory disease cycle in shelters
“Herpes is for life”
One quirk about herpesvirus infections is that once infected, infection is for life. Humans and dogs have their own herpesviruses that are distinct from the one that causes respiratory disease in cats. Herpesvirus can be spread from one cat to another, but most cases of URI that occur within a few days of shelter admission are caused by recrudescence. When a cat recovers from URI caused by herpesvirus, the virus retreats to specific nerve bundles to hide out and wait for an opportunity to reemerge (aka recrudesce). The key that unlocks the door to release the hiding virus? Cortisol, aka the “stress hormone.”
While shelter admission is almost invariably stressful for any cat, we have learned that the housing we keep them in plays a HUGE role in whether or not they will develop respiratory disease secondary to stress.
What the Research Tells Us About Cage Size
A multi-shelter study tracking nearly 18,400 cats over one year identified a critical protective factor against URI: larger cage floor space.
Cats housed in cages providing more than 8 square feet of floor space had dramatically lower URI rates compared to cats in smaller housing. When cats experience the compound stressors of shelter admission plus inadequate space, latent herpesvirus infections activate.
The ASV Guidelines recommend 11 square feet of floor space for individually housed cats (no less than 8). Meeting this standard requires either providing more space per cat by lowering the shelter population or replacing existing housing with larger units. Most shelters don’t have empty space waiting to be filled, which means the first option is often more feasible.
Why Larger Housing Matters
Cats in cramped quarters cannot perform normal postural adjustments, stretching, or play. They cannot separate elimination areas from eating and sleeping spaces. This causes chronic low-level stress that suppresses immune function and normal behaviors like grooming, eating, and exploration.
Double-compartment housing with portals allows cats to express choices and more control over their environment. They can move toward or away from an approaching person. They can choose to be seen or to hide. They have different surfaces to select for a resting surface.
The Portal Solution
Installing portals between existing single-compartment cages is a less expensive approach to meeting housing size recommendations compared to purchasing new cages. This inexpensive modification:
- Doubles the floor space per cat (from approximately 5-6 square feet to 11-12 square feet)
- Allows separation of resting and toilet areas
- Enables spot-cleaning without handling or removing the cat
- Prevents shelter acquired respiratory disease!
- Reduces the total number of available housing units by half
That last point causes understandable concern. However, shelters that have made this change report the opposite of what they feared. Rather than serving fewer cats or increasing euthanasia, they see healthier cats, faster adoptions, and often the ability to provide care for more cats over time.
The number of animals a shelter can care for is based on flow-through capacity, not holding capacity. A shelter that takes in 10 cats per day with an average 20-day length of stay needs 200 housing units. If length of stay drops to 10 days, only 100 units are needed while serving the same number of cats over time. This is why reducing the number of housing units doesn’t necessarily reduce the number of cats served – it depends on how quickly cats move through the system to positive outcomes. And after installing portals, most shelters find cats automatically move through more quickly.
Three Canadian shelters implementing this housing change as part of a comprehensive Capacity for Care model saw isolation populations drop by 39-84%. One shelter’s isolation ward, previously operating at maximum capacity with 16 cats, dropped to an estimated 10-15 cats for the entire year.
Real-World Impact
When cats are housed in appropriately sized double-compartment units, several positive changes occur:
Healthier cats. Reduced stress means fewer cats experience herpesvirus recrudescence. Cats who are sick are easier to manage because isolation isn’t overwhelmed.
Faster adoptions. Cats in larger housing can display more normal, active behaviors. They’re not curled in a corner trying to make themselves small. They stretch, play, and engage with people passing by, all of which increase adoption probability.
Sustainable operations. When fewer cats become sick, staff aren’t overwhelmed with treatments. Resources previously spent on isolation care can support adoption programs and preventive care.
What You Can Do Now
The research points to immediate, practical actions:
Review your data and calculate the housing capacity you actually need. Use historic intake data to determine how many cats you need to be able to house humanely in your busiest season. Use a target length of stay of no more than 14 days. I’m betting you’ll find that cutting the number of cages in half for portals won’t be a problem!
Prioritize double-compartment housing. If replacing housing isn’t feasible, install portals between existing single cages. This modification reduces available units but provides humane housing that supports health and faster adoption.
Moving Forward
URI is not an inevitable consequence of sheltering cats. It is the predictable result of an environment that fails to meet cats’ physical and psychological needs.
The solution starts with appropriate housing. When cats have adequate space and opportunities for choice, they experience less stress. Less stress means less URI. Healthier cats leave faster, creating capacity to help more cats over time.
Shelters implementing evidence-based housing standards don’t just improve individual cat welfare. They create conditions that reduce disease, support staff wellbeing, and increase lifesaving capacity.
In our next post, we’ll explore the other critical factors that work alongside appropriate housing to prevent URI: managing length of stay and optimizing daily population.
Want to learn more about implementing these changes at your shelter? Paws to Elevate provides expert consultation on cat housing design, population management, and operational systems that support humane, sustainable care. Contact us to discuss your facility’s needs.
