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Dr. B.
Dr. B., Cat Veterinarian
Category: Cat
Satisfied Customers: 22450
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 is being treated 2x 2.5mg felimazole

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Hi my cat is being treated for hypothyroidism 2x 2.5mg felimazole a day. The symptoms such as weight loss have improved but other symptoms have begun. She screams randomly not as her owners, just goes on her own and screams\ howels. She drinks a lot of water, so much so we have put an extra bowl outside. She also sleeps outside, hardly coming in!
Are these common side effects.
Thank you

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

Now these are not common signs associated with treating thyroid disease. We can see them in untreated or unstably treated cats. But in your lass's case, if she is suddenly becoming restless, drinking more again, and vocalizes excessively without apparent reason, I am concerned that she may have developed hypertension (high blood pressure).

High blood pressure can be an old age change but can also be precipitated by underlying kidney issues, heart issues, or metabolic conditions like hyperthyroidism. Since she has been under treatment for thyroid disease, I would be concerned that this change is actually related to her kidneys. This is because when we slow down that thyroid, we slow down the heart rate/blood flow. And if the kidneys were struggling (as they often do in older cats), that could make a difference to a coping kidney that was taking advantage of that increased rate. So, sometimes we see kidney disease suddenly become a clinical problem (though it was coping before) when we treat the thyroid. It is a true catch-22. And if that is present, it too could be the trigger for high blood pressure (and her thirst).

With that all in mind, to determine her blood pressure is elevated, you can have her vet check her blood pressure. This is something that is done conscious and can often be performed during a consult (or sometimes we will admit stressy cats to let them settle before taking a reading). If it is high, there are treatments that can be used to bring this down and the vocalizing usually declines with the blood pressure. And if you have a urine or blood sample just tested for her kidney function, that too can be medically managed. (Just to note treating that with drugs like Semintra, can actually help with both when present).

So, this would be my concern for your lass. We can see the crying with dementia, but usually not the thirst. And her signs just sound very suspicious of the above. Therefore, I would advise having her blood pressure tested if she has started to drink more and vocalize in this manner. If she is nearly due for a booster, then you might consider having her blood pressure checked at the same time. And depending on your findings of that, your vet can help address this for her.

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 2 years ago.

Thank you for your quick response. As an elderly cat, say her kidneys are the culprit is her quality of life assured with all these drugs. She is a very stressy cat so blood tests are always an overnight affair due to sedation.

I just had a horrible feeling the sleeping outside is her way of saying goodbye. But she is eating and drinking so I guess she is as you described and still poorly.

Thank you again

You are very welcome, Lucy.

If she is sleeping outside, it can be a sign of withdrawing due to feeling unwell. Though that said, if the weather is nice, then that too can be a factor.

Anyway, if she is so stressy that they need to sedate her to do anything; do consider collecting a urine sample first. You can do so by keeping her overnight in a non-carpeted room with an empty litter box. If the vet tests the sample and finds it dilute, then we'd be highly suspicious. And as none of us want to be constantly sedating an old dear when we don't have to, they may be willing to just try her on medication to see if she responds to treatment. And if she does, we can still get some good quality time with them on these treatments. So, it'd be a bit less straightforward for diagnosing but potentially a better approach for her.

All the best,
Dr. B.
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