Can stress make cats sick?

Yes, stress can make domestic cats sick. It's the same with people which clearly supports the argument that stress makes domestic cats sick. The best-known sickness arising out of stress is feline idiopathic cystitis. This is cystitis with no known or obvious cause. 

 Can stress make cats sick? Yes, but not in this cat. Photo: MikeB

It's ironic because the cause is often stress. The condition is better described as feline interstitial cystitis (FIC) which is a chronic pain syndrome of domestic cats. It is basically a recurring cystitis the symptom of which is peeing in small amounts around the home. Sometimes to pee is bloody. Cats with FIC have chronic, recurrent lower urinary tract signs and other associated disorders that are exacerbated by stressors.

SOME PAGES ON STRESSED CAT - CLICK TO READ THEM IF YOU WISH.

They did a study on this in 2013. The study was entitled: Effects of stressors on the behaviour and physiology of domestic cats. They employed 10 healthy cats and 18 cats with FIC. The study was conducted at the Ohio State University Veterinary Medical Centre. They housed the cats in "enriched cages" for at least one year prior to the experiment! Comment: I don't like this experiment. It appears to be an abuse but it was done many years ago so there's no point in complaining.

All the cats were treated well in these cages with plenty of enrichment and interaction with people that they knew. They had food treats and were taken out of the cages sometimes. Then during the test days, they withheld all these pleasantries which made the cats' lives a lot worse. 

They tested the effect that this had on the cats. They found that sickness behaviours including vomiting, diarrhoea, anorexia or decreased food and water intake, fever, lethargy, decreased activity and a reduction in self-grooming occurred in varying amounts in both the healthy and the FIC cats.

However, in cats suffering from FIC they found that there were changes in lymphopenia and N:L (neutrophil:lymphocyte). Lymphopenia is a condition in which there are less than the normal number of lymphocytes, a type of white blood cells in the blood. White blood cells are part of the immune system as they attack invading organisms. Therefore, a lowering of white blood cells will reduce the cat's immune system.

The neutrophil:lymphocyte ratio is a method, as I understand it, to measure stress. It is the number of neutrophils divided by the number of lymphocytes. Under physiologic stress, the number of neutrophils increases while the number of lymphocytes decreases.

Can stress make cats sick? Yes, as is the case in humans and the most commonly associated illness is feline idiopathic cystitis. You can read about that disease by clicking on this link if you wish. The main cause of feline idiopathic cystitis is conflict with another cat in a multi-cat home.