Possible impact of human chemo on a cat

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This may be an odd one. Last year when my husband suffered from diarrhoea as a side effect of chemo our cat also had terrible diarrhoea too for a couple of days. My husband had the same problem at the end of his first cycle this year and is now in the middle of the second cycle. So far he hasn’t had this side effect but tonight the cat had dreadful diarrhoea once again. Just once and in the litter tray (last year was the same). He’s an old cat and he has really bonded with my husband since he was diagnosed. The cat sits on his lap for long periods of the day and also gets lots of petting and belly rubbing on the floor. 

Has anyone else experienced this? It seems that the chemo is implicated because normally the cat doesn’t have any significant bowel problems. But I’ll accept it’s just coincidence if no-one has had it happen. I googled it and couldn’t find anything.

  • Hi MaryJay

    That's not something that I have heard of. Maybe ask the vet?

    I had chemotherapy during 2022 and have 3 cats. 2 older and 1 younger. They were constantly with me but none seemed affected. Probably just a bit more docile/affectionate but that could be the change in routine as I wasn't at work.



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  • Thank you for replying. I did ask my vet but he hadn’t heard of a connection. Hopefully it’s just a coincidence 

  • I had a look on line and I can't see anything that says there is a risk to cats. It's more that the person having chemo is potentially at a small risk of picking something up from the cat. However its a case of washing hands, avoiding scratches etc. Pets are generally seen as really positive during cancer treatment. Mine were a great support and encouragement to keep going. I hope it was just a coincidence for your cat- maybe it has just sensed that something different is going on and that has caused a bit of a tummy upset. Mine definitely picked up that I wasn't well 


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  • Thank you for taking the time to look this up for me. I found the same information. I do think the cat is being affected somehow but you’re probably right that he just senses it. It’s just so odd it’s happened a year apart on two lots of chemo. But then he is a funny little cat lol

  • Hi my husband has just completed his adjuvant capox chemo and we advised for him not to cuddle children under 2 and babies and small domestic animals as the chemo is strong and can be excreted through the skin. He also had to double flush the toilet after wee's 

    I know all chemo is different but that was the advice given to us. 


  • Thank you so much for that info. I don’t feel so daft now. My husband will reduce the amount of stroking he does and hopefully there won’t be any more cat diarrhoea. He’s just told me he’s supposed to double flush too but he ‘forgot’. What can you do lol

  • Not daft at all. I would hate to think I had done anything risky with mine. They are real lap cats as well. Maybe its different chemos. I have a check up in a couple of weeks and I am going to check with my oncologist.


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  • Thanks Jane. That would be great Blush 

  • Hello. Just looked this up on Google and apparently cats not affected by human having chemo. Might be idea to check cat with vet too see if he is OK. Could be he needs worming? Also important. He doesn't pass anything, to tour husband.

    My ziggy. Knows when I'm poorly qnd sticks to me like glue. Crying cat faceGreen heartBlue heart

  • I think it depends on the chemo we were told not to.cuddle babies and toddlers under 3 and small animals when my.husband was on Capox.