Hello again, Donna and thanks for your patience. I had a lot to write, as you can see! : )
I'm sorry Tiger is experiencing these symptoms. Was he ever actually diagnosed with hyperthyroidism, through a blood test? The symptoms you described are classic for hyperthyroidism, but can also be signs of other medical conditions in older cats, like diabetes, which you mentioned he tested negative for, and also, kidney disease.
Depending on his dosage and how long he has been on the medication for hyperthyroidism, if you don't see much improvement in his current symptoms, he's either becoming stabilized on the medication, to see which dosage is best for him, or if your vet prescribed the current dosage and is not doing regular blood work to check his levels, his dosage may need to be adjusted so they have more of an impact on his symptoms.
Capillaria felis cati and Capillaria plica are worms that can infest the urinary bladder. This may be the cause for Tiger's frequent UTI's and the worms also cause a painful condition, which can cause urinating outside the litterbox, if they associate the box with the pain. I hope you kept the worm and can show it to your vet and discuss treatment for this condition. Here is more information:
If there is no UTI and Tiger is still urinating outside the box, in addition to the worm, he could have a condition called feline idiopathic interstitial cystis which typically has no known cause, however, sometimes, stress can be a contributory factor. It carries the same symptoms as a UTI, but is not an infection. This also causes discomfort/pain upon urination, If this is the cause, some dietary changes may need to be made and the vet can prescribe a medication/painkiller that will help with the discomfort. Here is more information:
You can get a Feliway plug in diffuser to help with stress:
It's also very important that you clean the areas he's soiled with an enzymatic cleaner for organic (pet) stains and odors, like Nature's Miracle, Zero Odor, Odor Mute and many others found in your pet supply store. Other stores like Walmart and home improvement stores may also carry this type of cleaner. It's important to clean the areas very well, so he doesn't keep returning to them, thinking they are acceptable toileting places.
I hope you're able to have Tiger seen by his vet, asap, so a thyroid panel, urinalysis and testing of the worm can be done and then the most appropriate treatments will be prescribed.
My best wishes that Tiger will soon be feeling better and back to himself!
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