The Effect Of Stress On The Canine And Feline Immune System


Ask anyone if he understands the concept. You may get some quizzical looks, because we all have it.

Today I was treating Spring Gale for a urinary tract infection (UTI). Her owner had mentioned that she had company at her house. We also discussed the fact that on June 17, 2008, Spring had a UTI. I inquired about whether Spring had been under any stresses during that time.

“Sure,” she said. “That was when I was going back and forth to the hospital as my husband was dying of cancer. Why are you asking questions about stress?”

Stress, I explained, has the same diminishing effect on immune systems of all mammals. When we are stressed physically or psychologically our immune systems don’t operate at full capacity.

Let’s look at some scenarios.

In the first scenario, let’s use Spring’s owner’s experience. Driving back and forth to New Orleans every day, watching her husband suffer and wither away, then get up and do it all the next day, seven days a week for months. If, during that time someone with a cold had hugged her, she would have been very susceptible to coming down with that person’s cold.

In the second scenario let’s look at this same couple a few years ago, as newlyweds. They were both working in jobs they enjoyed, their marriage was happy and life was good. If someone with a cold had hugged her under those circumstances, chances are good that her immune system would have shrugged off the cold virus and she would have remained healthy.

Physical stress can be as hard on the immune system as emotional stress. Say this couple was honeymooning at Disney World. They’re happy, healthy and having the time of their lives. But, there was that twenty-hour drive they made all in one leg to get there sooner, the poor nutrition in the fast food they ate along the way, the sleep they missed on the trip, and the sixteen-hour sessions they were cramming in to make the most of each vacation day. All that loss of sleep and go-go-go adds up to stress. If someone with a cold hugs one of them now, chances of getting that cold are near 100%.

Spring Gale had the stress of her daddy’s absence and her mom’s worry and travel last year, and she became susceptible to UTI. This year she had a crowd of visitors at her house and an upset schedule. It all adds up to stress and an increased susceptibility.

Any time you can decrease your pet’s physical and psychological stress you allow him to be as healthy as he can be.

Have a wonderful and safe Memorial Day, see you Tuesday, Dr. Randolph.


  1. Thank you, Dr. Randolph, for this insightful post about the effects of stress on animals’ immune systems, as well as for all the other posts and information you generously offer. I have found your site always helpful and thought provoking. I happened upon this particular post because I have had the odd experience over the last few months of both of my female cats, on separate occasions, getting and being treated for UTIs. Pearl is about 13 years old (an estimate, because , obviously abandoned, she ” found ” me one cold night as I was walking home and my vet could only guess at her age); Emmy is 17 years old.

    Let me just preface this by explaining that Emmy is extremely “vet phobic,” and is the kind of cat who has a total personality flip whenever she goes to the vet or senses anything “vet like” near her. In short, she gets fearful and then aggressive, to the point where she simply does not go unless there is something absolutely wrong.

    This being said, three months ago, friends who had dropped in for a brief visit commented that my other cat, Pearl, had lost weight and seemed frailer than usual, something that I hadn’t noticed since I see her every day. Anxious, of course, I called my vet and made an appointment for the next day, whereupon I assembled the cat carrier that I use only for trips to the vet, captured Pearl, deposited her into the carrier, and off we went. She was diagnosed with hyperthyroidism and given meds and brought home (and doing every well on the meds now, I might add). The very next morning, Emmy started running back and forth between litter boxes in obvious distress, at which point a vet visit was necessary, and so with much ado and plenty of scratches on my arms and hands, I managed to get her in her carrier and to the vet, where she had to be sedated before they could examine her. Sure enough, she had a UTI and was injected with Convenia (and I thank the powers that be for that medication!). She came home, her symptoms and distress disappeared by the next day and all was well until this weekend, at which point I had a guest from out of town.

    Now, prior to this guest arriving, I had had a very stressful work week and had been scurrying around to get my small apartment ready for her arrival at the last minute on very little sleep. The guest arrived and things were rearranged for her stay and I thought we had all settled in for her visit when Pearl began running from litter box to litter box and suddenly showing the same symptoms Emmy had had when she had her UTI. My vet has late hours and I was able to get in that night and so my guest and I spent the first evening of her visit at the vet’s office, where Pearl was also given an injection of Convenia and then brought home. A day later, the injection obviously working, her symptoms abated. My friend and I were able to go out and sight see and she will leave today after a whirlwind visit.

    I write all of this in response to your post because I am beginning to believe that both of these UTIs may have been exacerbated by stress. They have never had UTIs before, and I am changing their diets and taking other precautions against future episodes. And I also recognize that they are elderly animals who are now more vulnerable to diseases so that might explain some or it. At the same time, your insights about the effects of stress on cats’ immune systems have been an eye opener for me. I am really wondering now how stress may have contributed to the onset of these UTIs–for Emmy, the scent of the vet’s office in her home after Pearl returned (and the “scent” of my anxiety and the trip to vets); and for Pearl, her picking up on my stress about work and the sudden disruption of her environment when my guest arrived.

    Just some of my thoughts about this. Again, thank you for YOUR thoughts so I could start making some connections.

    • I’m sending you some links to other articles that address some of the comments and questions you’ve posed. Clicking on this link will take you to a list of articles, some of which address Feline Lower Urinary Tract Disease directly. Talk to your local veterinarian about the possibility of using Hill’s Prescription Diet c/d Stress for Emma and Pearl. If you want your veterinarian to work with a board-certified behaviorist, and he doesn’t already have a “favorite,” Dr. Martin can help to advise him about ways to reduce Emmy’s phobias. We, too, used to have a baby named Pearl. Thank you for reading our blog, and for your kind comments.

      • Thank you so much for the links and your helpful response. AND for taking the time to read my original comment . I tend to be long-winded, so appreciate the time you took to do so. I’m happy to hear you also had a baby named Pearl. I’m sure she was as special to you as mine is to me. All the best!

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