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Dr. B.
Dr. B., Cat Veterinarian
Category: Cat
Satisfied Customers: 22590
Experience:  I am a small animal veterinarian with a special interest in cats and am happy to discuss any questions you have.
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My cat has a thyroid problem and has been placed on the new

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My cat has a thyroid problem and has been placed on the new Hills Y/D food which she doesnt like. Since she has been put on this new food things have started to go wrong with other aspects of her health. She can get badly constipated and now she is drinking more than double her water intake then usual and peeing constantly in and out of the litter tray. All these symptoms have only started since the new food was introduced. she was previously on Hill R/D and she was never this ill before. I have spoken to my vet and he thought she had an infection so gave her an anti inflamatory and an anti biotic injection as my cat does not take pills as this really stresses her out. Do you have any advice that I can approach my own vet with regarding this as I have spent over £250 taking her back and forward to the vets and my cat just doesnt seem to be getting any better.



Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you with your wee one today.


I must say that I am quite concerned about Misty. The signs you have described (ie the increased thirst, urination, yet constipation which is likely because the body is taking up too much water from the feces) do not directly fit with her diet. Instead, I am concerned that she may have also had underlying kidney disease at the time of her overactive thyroid being diagnosed.


The dilemma we face with old cats is that they can have more then one health issue at a time (just as old people). And we can actually find an hyperthyroidism will mask kidney disease. This happens because as I am sure you are aware, hyperthyroidism causes increased heart rate and blood pressure (since the body is essentially on "fast forward" when its the thyroid hormone levels are too high). This means that before the thyroid treatments, her kidneys were getting blood pumped through them twice what is normal. And if kidneys are getting old, struggling to function, and filter as they should, then more opportunity to filter the blood will allow them to do their job better even though they are compromised. And when we then treat the thyroid, thus leading to a normalization of heart rate and blood pressure, the fact that the kidneys are struggling can then become apparent.


In this situation, I would suggesting ringing her vet to review the bloods that were initially taken. If they did a general health profile at the same time as the thyroid levels, then they may be able to appreciate a hint that kidney disease was there before (ie if they were borderline high normal levels before treatment). Otherwise, you could consider taking a urine sample in for a quick check of its specific gravity. If her kidneys are struggling then the urine will be abnormally dilute. And this is a simple and inexpensive test the vet can do in practice to give us a hint if this is our issue with Misty (they can also check for bacteria, white blood cells, etc. to confirm if there is a possible bladder infection). And of course, if you wished, you could have them recheck bloods just now to tell you what is likely amiss.


Overall, based on her history and her deterioration with treatment for an overactive thyroid, I'd be concerned that her kidneys have been struggling for a wee while and this is now becoming apparent as her thyroid settles. Therefore, I would advise a chat to her vet about her previous kidney values on the blood sample and consider a urine (or blood) test to confirm this situation. If her kidneys are struggling, then there are treatments that can help but her overall prognosis would depend on how severely they are affected.

I hope this information is helpful.

If you need any additional information, do not hesitate to ask!

All the best,

Dr. B.


If you have any other questions, please ask me – I’ll be happy to respond. Please remember to rate my service once you have all the information you need. Thank you and hope to see you again soon! : )



Customer: replied 4 years ago.

When I took her in for her infection earlier this week the vet had already looked at the levels in her blood work that had been taken when she was diagnosed with her thyroid problem and said they were ok and that is why they said infection rather than kidney problems. Do you think i should stop feeding her the Y/D as that to me is the route of her thirst as she was never this thirsty or running to the toilet when she was on her other veterinary food. I really feel that my vet at the moment is just saying sit tight and let things run for now rather than looking as to why she is suddenly like this.


Thanks for your help.

Hi again Dee,

As I noted before, I would question where the blood values even if they were in the normal range but perhaps borderline or at the higher end of normal (since that "snapshot" of their function was when they were getting a "boost" from her thyroid). And if there is any doubt about those levels relative to her current signs, I'd suggest a urine sample would give you a good indicator if they kidneys are really ok (and its a cheap test that you can bring a sample in for without dragging Misty in again at the moment).

In regards XXXXX XXXXX the diet, this may change her current signs but you have to appreciate that her thyroid levels will skyrocket again potentially leading her back to what signs she was showing when you originally diagnosed the thyroid disease. And while this was perhaps more manageable, we'd still be concerned that with time the negative effects of that disease would cause her to deteriorate (since they tend to lose weight, waste away, and can develop secondary heart failure because the heart cannot beat as fast as the thyroid disease makes it for the longer term). So, its a catch-22 situation. Treating one can increase the severity of another condition, but not treating it means the first disease will progress and cause its troubles for her.

Finally, in regards XXXXX XXXXX vet's approach, it is reasonable to sit tight if she just didn't like the diet and we are trying to win her over. Still with these other signs, I have to say that it is a not ideal to just sit tight. So, I would really advise at least a urine sample at the moment to tell us if we have bladder infection (which I suspect is the focus they are concerned about with her signs) or that she isn't concentrating her urine and kidney troubles may be rearing their head. That way, we'd know if we need to be patient or if we need to address this second issue for Misty.

All the best,

Dr. B.


If you have any other questions, please ask me – I’ll be happy to respond. Please remember to rate my service once you have all the information you need. Thank you and hope to see you again soon! : )



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