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My cats suddenly started fighting. Could one be sick or unwell?

Updated on September 23rd, 2025

My friends cats have begun fighting after getting along for quite some time. She knows that means someone I'd sick but which one and with what possibly?

1 Answer

Most Helpful Answer

Destini R. Holloway, DVM

Answered By Destini R. Holloway, DVM

Veterinarian

Published on February 15th, 2017

Those are tough questions to answer without being there to visualize each cat. But I would say generally speaking whichever cat is acting abnormal. Abnormal behavior can mean anything from the cat being lethargic (lacking energy), vocalizing more, drinking more water, or even going to the litter box more frequently.
As far as what illness could be causing this, there isn't enough information as of yet as to what symptoms either cat is displaying besides be increased aggression. Do some monitoring of both cats over the next few days to gather clues and then feel free to repost your question with specifics so that we can discuss some possible causes.
However, in general we do worry about kidney and urinary infections in cats. Also a change in mood could indicate an endocrine disorder, brain malfunction or even diabetes.
I hope this helps and look forward to more information about your fur babies. I do hope we can figure things out soon and get them to being friends again.
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