Vetinfoindex
Vetinfo4cats
Catindex
Subscriber Area (members only)
Zoonotic disease
Becoming A Veterinarian
Your Turn
Search vetinfo4cats
Support Vetinfo and Subscribe toVetinfo Digest
Hormonal Disorders of Cats
Acromegaly
Hypothyroidism and
diabetes
also see Hyperthyroidism
also see Hyperthyroidism Treatment
also see Heart
also see Vomiting
also see Weight loss
also see Medications
- also see Radiocat - a veterinary
site dedicated to the treatment of Hyperthyroidism
Question: Dear Dr. Mike,
I am a subscriber to Vetinfo Digest.
I would like to know more about acromegaly in cats and how common it
is.
I have an 8 month old kitten who is very large framed, well muscled
and
now weighs over 15 lbs. His littermate is smaller, a female at 10 lbs.
I
am wondering if he could have acromegaly or will prone to it later
in
life. Although he's extremely healthy and active I've just never
known
a kitten this huge with a tail that long!
Thank you in advance,
Judy
P.S. You've also given me good information about my older diabetic cat
who is now doing well on PZI insulin.
Answer: Judy-
Acromegaly is a disorder in which there is overproduction of growth
hormone. It usually occurs in adult cats approaching "senior" status,
due
to pituitary gland tumors (pituitary adenomas) that produce growth
hormone.
This causes widening of the facial structures which is sometimes easiest
to
appreciate by looking at the teeth, which move apart as the bone grows,
although thickened facial folds, abdominal enlargement, increases in
organ
size (heart, liver, kidneys) and other growth related symptoms
may appear.
This is not likely to be causing the increased size of your male cat
compared to his sister. It doesn't sound like he is overweight by your
description, either, but you might want to ask your vet on the next
visit
if he is a good weight for his size.
It sounds like you probably have a normal cat who is just a big
boy. Hope so!
Mike Richards, DVM
3/2/2000
Hypothyroidism and Diabetes in cats
Q: Dear Dr. Mike,
I read, with interest, the last VetInfo Digest about drugs and drug
interactions especially concerning Levo Thyroxine. I wrote you
some
weeks ago about my cat, Oliver, who was diagnosed with both
hypothyroidism and diabetes. Although you mentioned that Levo
Thyroxine
increases insulin requirements in dogs, I've found that it also acts
the
same way in cats. I was unable to regulate Oliver on insulin
until my
vet contacted the pathologist from the lab which does the blood work
and
he suggested taking Oliver off the Levo thyroxine completely.
Doing so
has markedly decreased his insulin requirement.
I am wondering if hypOthyroidism in cats, rare as it is, contributes
to
diabetes in any way. I 'converse' with others on the Feline Diabetes
Message Board and seversl of us own cats who have both these diseases.
Do you have any information on this?
Thanks in advance!
Judy
A: Judy-
In cats, hypothyroidism is considered to be very rare. So rare that
I have
only seen one clinical case report involving more than one cat and
it
related to congenital hypothyroidism occurring in two kittens who were
littermates.
There is a condition known as euthyroid sick syndrome, in which total
thyroxine (total T4, TT4) levels fall below normal levels due to other
illness but the thyroid gland is actually OK and meeting the body's
need
for free thyroxine (free T4, fT4), sometimes fTT4). Since free thyroxine
is
the active form in the body, the cat is actually euthyroid (normal
thyroid
hormone levels) despite having the low total T4 values. This almost
certainly occurs in some cases of diabetes and can occur with any illness
that is chronic or severe. Since it is common to run TT4 tests to try
to
rule out hyperthyroidism in cats who are aged and ill, due to the
prevalence of that disease, there are starting to be a lot of reports
of
low total T4 levels in cats. This happens due to the euthyroid sick
syndrome in most cases but it is really tempting to treat these cats
with
thyroxine when many of the symptoms of hypothyroidism are present.
The best way to differentiate between these conditions for most
practitioners is to run a free T4 test. If the serum level for free
T4 is
also low, there is a better chance that hypothyroidism is present.
At that
time a clinical trial with levo-thyroxine may be indicated if it is
not
possible to do TSH response testing (most practices can't get TSH anymore).
This has to be done cautiously since cats are susceptible to effects
of
hyperthyroidism much more commonly than dogs.
I think that it is probably best that you have discontinued l-thyroxine
supplementation, as suggested by the specialist. If signs of this problem
return it will be possible to do accurate free T4 testing in three
or four
weeks.
Hope this helps in the understanding of what may be going on.
Mike Richards, DVM
7/27/99
Last edited 01/30/05
VetInfo Digest |Links