Hi everyone and welcome to the second of my three clinical videos on the three most common
age-related health conditions in cats today i'm being joined by creature to talk about
hyperthyroidism which is one of the three most common age-related conditions in cats
now this beautiful creature named creature has hyperthyroidism she's a little hyperthyroid cat so
i think she'd be very nice to have her illustrate it if you have cats in your life there's a roughly
five to ten percent chance that they're going to develop hyperthyroidism at some point in their
life and she's just a little bit growly because claudia was just in here and her and claudia
don't get along very well so they're having some discussions so what is hyperthyroidism
what it is is a little functional tumor in the thyroid gland which is a little gland that sits
right in the neck uh sort of just the bottom of the neck above the thoracic inlet and it
produces thyroid hormone and the easiest way to understand what thyroid hormone does in your body
is to think of it as a thermostat that kind of controls your body's metabolic levels so if you
have a little functional tumor that's producing a thyroid hormone and you have too much tired
hormone in your system everything gets turned up so your body temperature gets higher you get
anxious nervous your blood pressure goes up your heart beats a little faster so it's like all the
physiologic processes just get turned up and this is what leads to the symptoms of hyperthyroidism
hyperthyroid cats tend to be anxious they see a little growly here and a little reactive they
tend to be very heat-seeking they're always cold they're always shivering they can show aggression
towards their owners or other cats what they didn't show it before they usually lose a lot of
weight they develop a heart murmur they basically just look like skinny kind of scruffy their coat
looks bad like skinny scruffy kind of twitchy anxious maybe scary older cats so if your cat's
looking like that maybe it has hyperthyroidism maybe it's just a terrifying trash goblin
the thyroid gland also is palpable so you can feel it in the neck with your fingers and a part of a
health exam for any older cat you might see the vet running their fingers along their neck and
what we're doing is we're feeling fed a little bump that tells us that there's a little mass
in the region of the thyroid of course we can't diagnose this disease on clinical signs alone
which is why we always measure thyroid levels in any older patient and as a part of our regular
screening blood work that should be done on every cat over the age of eight at least once a year
is checking their total t4 so total thyroxin hormone and people often ask me why cats get
hyperthyroidism and there's really no clear answer for that we think it's mostly a genetic
thing where certain breeds are definitely less or more likely to get it than others
so it's a sort of natural process of aging in cats a significant percentage of them will just develop
these little functional thyroid masses diet can also lead to hyperthyroidism and cats who are fed
like only fish for example are predisposed to it and certainly some canned foods did
increase risk of developing hyperthyroidism historically it is important to note that the
connection between diet and hyperthyroidism was identified decades ago and that it's no longer
a problem as pretty much everybody who makes cat food is aware of it so unless you're feeding your
cat a homemade diet made entirely of fish and you really don't need to worry about it every cat food
manufacturer out there accounts for this and tries to avoid causing hyperthyroidism with their diet
but yeah diet and genetics some interplay there and you can't necessarily prevent hyperthyroidism
with diet but diet does play a role in managing it which i'm going to talk about in a minute
so first we diagnose hyperthyroidism usually on screening blood work sometimes we actually see
a cat who maybe hasn't had blood work in a few years come in just looking hyperthyroid and then
we recommend a blood test and what the vet will see is an elevated t4 and a blood work
sometimes the t4 can be kind of within normal limits but maybe top of normal and in those cases
the veterinarian will ask you to for permission to run on a secondary test called a free t4 you don't
really need to know what that is all you have to really have to know is that a free t4 is a more
sensitive test for thyroid disease so we run a total t4 as a screen and then a free t4 to confirm
diagnosis if it's needed once your veterinarian has done screening blood work and found elevated
thyroid levels they're probably also going to want to measure your cat's blood pressure because high
blood pressure is a pretty common feature of hyperthyroidism and they also if they're
really switched on they can do something called a funding exam which is done with a special lens and
a light to look into the back of the cat's eye to evaluate their retinas unfortunately cats who have
high blood pressure will sometimes have little hemorrhages in their retinas and can this can even
lead to retinal detachment which causes blindness and you can often find that uh with a funding exam
so a hyperthyroid patient usually gets a blood pressure and eyes examined to look for secondary
changes uh to the hyperthyroidism or it might go the other way it might be that during your
geriatric health check the veterinarian measures their cat's blood pressure
finds the blood pressure is high has a look in the eyes sees if he hemorrhages and goes like
maybe we should check the thyroid level to make sure we're not hypothyroid another common thing
that that's fine with hyperthyroidism is a heart murmur because the thyroid hormone does change
cardiac function so you get a little thickening of the heart muscle and these cats often
develop a murmur the good news is that these murmurs are usually not pathologic so you just
manage a hyperthyroidism and the cat might have a heart murmur for life but they don't really
develop heart failure and it doesn't really you know technically it's heart disease but
it doesn't really mess with their heart too badly so that's the good news of course the
high blood pressure will mess with the heart so you still need to manage the thyroid disease but
the heart murmurs in hyperthyroid cats are very rarely do any further diagnostics on them unless
they're showing signs of heart disease usually it's just you manage the thyroid and the heart
takes care of itself sometimes you might also find elevations and liver enzymes on the blood work of
cats with hyperthyroidism again this is just all due to the action of thyroid hormone in your body
and if you just focus on managing the thyroid disease you know the heart murmur and the
elevated liver enzymes take care of themselves so how do we manage with hyperthyroidism well
we have basically two tools at our disposal we can do medical management or we can do iodine 131
therapy i'm going to break that down for you guys in a minute here but i just want to say that there
have been surgical solutions proposed to this like doing a surgery to remove the thyroid gland
but they're no longer done and it's not really a good idea because medical therapy and iodine
131 therapy are both way safer and more effective and just there's no reason to ever do surgery in
one of these guys so yeah just i want to put it out there there's no reason to ever do surgery
for hyperthyroidism there's much better tools and safer tools to manage this disease in cats
medical management consists of just giving a pill or liquid medication or is in some cases
even transdermal medication that lowers the body's production of thyroid hormone
it works really well it is very effective like i said the medication can be given
as pills or liquid or transdermal and what transdermal is is a fantastic tool for delivering
medications to the body it's just a little gel you smear usually on the inside of the ear and
the drug gets absorbed through the skin which you know for cats who are difficult to medicate orally
it's a great great solution when you start doing medical management for hyperthyroidism
there's usually some follow-up blood work involved about three weeks after you start medication
and that's because every patient will respond a little bit differently to the medication so you
start on an empirical dose and then you recheck the thyroid levels and if they're within normal
limits great you just do your like two or three times a year monitoring and if they're not you
adjust the dose recheck in another three weeks and you might have to go through a few rounds of that
until you get the dose just right and then you can just manage these guys long term on it or you can
try to cure hyperthyroidism so iodine 131 therapy is really cool what iodine 131 therapy is is
in a special facility your cat gets fed radioactive iodine and the radioactive
iodine localizes to the little thyroid tumor and it kills the tissue locally while preserving all
the healthy tissue around it it's really cool it's very specific targeted therapy it just
knocks off the tumor tissue and with that tissue gone the thyroid levels return normal
problem solved now of course nothing in the world is quite that easy one little caveat
is that the cat then has to stay in the facility for a week because their urine is radioactive so
it usually requires a week-long stay in this id 131 facility but most big cities have one and
they take really good care of the cats so it's a great great option ninety percent of the time
a single treatment is enough to cure the cat of hyperthyroidism in some cases they may require a
second treatment because obviously the dosing can never be 100 accurate in 100 of cases and
also in a small percentage of cases the treatment might overshoot and actually cause hypothyroidism
which is low thyroid levels that is unfortunate it does happen in small percentage of cats however
hypothyroidism is a way less bad illness to have than hyperthyroidism and a hypothyroid cat
will still need some supplementation with thyroid hormone to be completely normal this is more of a
dog problem like dogs get hypothyroidism all the time still needing the hypothyroid medication it's
way less stress and way less health risks than needing hyperthyroidism medication
and if you miss a dose it's not a big deal again so hypothyroidism is still
not the perfect outcome of iodine 131 therapy but it's still way better than being hyperthyroid and
still in the long term i think it's beneficial to the patient while for some people the upfront cost
of the iodine 131 therapy might be a barrier i've actually done the math uh with our local center
and i kind of figured that it does you know giving medication to your cat every day has a
i guess a lifestyle cost both to you and your cat and there's also a financial cost associated to
the medication and the regular blood test to monitor it so when i worked it out you
know the cost of iodine 131 therapy kind of it basically pays for itself within about
two years so if you expect your cat to live two years or longer which most of these patients do
once they've been diagnosed with hyperthyroidism because often it happens pretty early in life
id 131 therapies actually works out better financially for the owner and of course just less
work because you don't have to give medication every day to your cat so really really good option
and the way i usually approach these things is i stabilize these cats with medication and then
i send them for id 131 therapy if the owner is amendable to it that's my preferred approach and
i know some people send these cats straight for radioiodine therapy and i think that's something
you have to discuss with your vet but it's really legitimate both legitimate approaches and the main
thing i would like you guys to know is that this is a very manageable and in many cases
treatable condition now in recent years hills has produced a food called yd which they claim
is actually an effective tool for managing thyroid disease and they do have some data showing that
cats for a fed yd a vast majority of them their thyroid levels will return to normal now does this
represent a true treatment for hyperthyroidism or is this merely that they're improving the
lab variables that we're measuring while there's still some disease process underlying it i feel
like that question is a little bit open certainly feeding yd is a legitimate tool for management
hyperthyroidism and a lot of these cats do seem to do quite well on it long term but i feel that
the data supporting its use isn't as strong as everybody would like it to be and personally
i think it's still better to get these cats into iodine i-131 therapy and just get them cured then
do food or medication management and i still think that i have some arguments for why the medication
management might be more effective in dietary management but again i think in cases where
you can't give medication for whatever reason like having a really stroppy cat in those cases
dietary management with hills yd might be a really good option while you're waiting to get your cat
into id131 one thing that we need to be aware of when managing thyroid disease is that thyroid
disease often masks kidney disease and they often both occur in the same patient i have a video on
feline kidney disease that you should definitely look up and it'll be a link to it in the
description below if you have a cat with thyroid disease you should probably watch the video as
well because again many of these cats actually also have kidney disease but the elevated thyroid
levels mask it and once you start treating the thyroid disease then the kidney values come up and
then a diagnosis of kidney disease can be made so it's not uncommon on those follow-up blood tests
once you start treating thyroid cat to say oh well there's actually some degree of kidney disease
present here and then you discover it and you can manage that as well i figure it's just good to
know that these two conditions can co-exist and do so quite commonly so to sum up thyroid disease is
common it often coexists with kidney problems and the prognosis for it is excellent like these cats
as long as they get appropriate medical care tend to do well and they can do well for totally the
right page of 20 with medications they can do well with the right page of 20 with iodine 131 therapy
there's just we have some really good options for managing it and even if they do have concurrent
kidney disease managing the thyroid condition makes protective for the kidneys so it makes the
kidney problems easier to deal with so in general terms this is not a terrible condition to have
although obviously you know it's better not to have it if you have any questions about this
just so you know i will be doing a live cast approximately a week after publishing this video
so you can feel free to join me for the live cast and ask me questions during the live q a
session and of course if you're watching this video later on you can find that live cast
in the live cast section of my channel so thank you very much for watching i hope
you found this video to be very helpful and i look forward to seeing you next
time
you