"Kate" wrote in message
...

"Phil P." wrote in message
...

"Kate" wrote in message
...
Last January I posted regarding our almost-16 years old cat, Toby,
being diagnosed with hyperthyroidism. His T4 reading was 287 at
that
time, his weight had dropped from 6kg to 3.5kg and his appetite was
poor.

My vet prescribed Felimazole initially, 1 tablet twice a day and
after
two weeks his appetite had improved and he had gained some weight.
Two weeks further on, his weight had risen further and his appetite
was still reasonably good. However, he was drinking a phenomenal
amount and his urine output was copious. I also noticed that he
seemed
cold and the inside of his mouth was very pale. The vet said that
he
was anaemic and further blood tests showed that his T4 had dropped
to
5 and his kidney enzymes had increased. Felimazole was reduced to
1
tablet a day. He started to feel warmer and his mouth pinked up,
although his appetite dropped back again. His drinking and
urination
returned to normal. One week later he had a repeat of the blood
tests
which showed that his T4 had risen to 88 but his kidney enzymes
were
still high. As he seemed especially sensitive to the Felimazole,
he
was prescribed Neo-Mercazole instead at a very low dosage of half a
tablet twice a day. The vet also recommended putting him on a
special
kidney diet.

After his second dose of Neo-Mercazole he vomitted (something very
rare with Toby) and he would not eat the new food. The vet said to
stop giving him the Neo-Mercazole, and, as not eating was very bad
for
his kidneys, let him go back to his normal diet. Two weeks later
his
weight had dropped again and his appetite was poor. His heart rate
was high at about 184 beats per minute while resting, although at
the
vet clinic it climbed to 256. So the vet gave him an anabolic
steroid
injection to boost his appetite, plus prescribing Fortekor (which
is
not licensed in the USA but contains - if that`s the right word -
benazepril) to help his kidneys and also increase his appetite. At
the
same time, we were to resume giving Toby the Neo-Mercazole at the
same
rate as before. This was two days ago and until this afternoon he
hadn`t had a bowel movement and his appetite had dropped even
further.
Today the vet advised me to stop the Neo-Mercazole but to continue
with the Fortekor.

I do not know if not giving him the Neo-Mercazole made the
difference,
but this evening he had a very good bowel clear out and his
appetite
was a little better, although he is not eating sufficient to
maintain
his body weight even without the complication of the
hyperthyroidism.

So, we have a dilemma : if we continue to treat his hyperthyroidism
his
kidneys will pack up, but if we do not treat the hyperthyroidism he
will develop heart failure, or perhaps have a stroke. I get the
impression that the vet has not come across such a difficult cat to
treat for hyper-t and is struggling to find a regimen that will
help
without compromising his kidney function. If anyone has any hints,
tips, or clues as to what we could try next, I would be most
grateful.

Kate,

Hyperthyroidism with underlying CRF is indeed a dilemma. The only
way I've
any sucess in situations like yours is to restart methimazole
therapy at a
very low sub-therapeutic dose - 1.25 mg - once a day for a week,
then
gradually increase the dose and times until I struck a delicate
balance
between an "acceptable" level of hyperthyroidism and an "acceptable"
level
of azotemia. Sometimes, this can be difficult - but it can be done.

Starting therapy with very low doses followed by very gradual
increases will
also greatly minimize adverse effects because his body will have a
chance to
slowly adapt to the medication. You can also have carbimazole
reformulated
into a flavored suspension or into a gel that you apply to the
inside of his
ear flap. Just be sure to wear exam gloves so you don't absorb the
medication.

You can control the cardiovascular effects of hyperthyroidism with a
selective beta 1-adrenergic blocking agent such as Atenolol -- but
this drug
can be risky in a cat with CRF and will take a very careful
assessment of
the risk-to-benefit ratio. In a few situations I had no choice -
and
fortunately no problems. However blood glucose must be monitored
very
closely.

Best of luck,

Phil

Thank you so much for your help, Phil. I will pass on your
recommendations to our vet tomorrow (Monday). The way things have
been going lately, I am concerned that the yo-yoing of his blood
pressure will do even more damage to his kidneys and/or heart, so a
very gradual reduction sounds an excellent idea. I just hope we can
get it down soon enough to prevent heart damage, though...


Don't be too worried, Kate. Many hyperthyroid cats develop myocardial
hypertrophy that's often confused for hypertrophic cardiomyopathy.
Thyrotoxic myocardial hypertrophy often (usually) resolves when
hyperthyroidism is brought under control.




BTW, he is
an absolute star about taking pills, and his mouth is so huge, I can
hardly miss!

You're *so* lucky! That alone increases his chances *dramatically*!



My thanks again
Kate

Please keep me posted!

Best of luck,

Phil