Hi everybody. My name's Sophie McMurra. I'm a registered veterinary nurse and a veterinary technician specialist in small animal internal medicine.
I work for a specialist referral hospital in Frodsham called Northwest Veterinary Specialists, where I make a part of the internal medicine department, and I'm one of 4 head nurses. So today I'm gonna talk to you about hyperadrenal corticism, also known as Cushing's disease. So Cushing's disease is something that we commonly see in practise.
It's a very common condition in dogs, but it's very rare in cats. And it was first described by Harvey Cushing in 1912, who was an American neurosurgeon who realised that there was increased secretion of cortisol, secondary to a pituitary tumour. Now, we know that there are now 3 forms of the disease.
So there's a pituitary dependent hyperadrenal corticism or PDH, or there's a functional adrenal tumour. And then finally, there's iatrogenic Cushing's disease, and that's the the condition that we cause by putting the patient on steroids long term. So, we'll just briefly talk about the physiology of how things work on a normal day to day basis, so the negative feedback loop.
So this plays an important role in nearly all endocrine disorders, and it just helps regulate the plasma cortisol level. So, in the hypothalamus in the brain, we have corticotropin-releasing hormone or CRH. This is released and stimulates the anterior pituitary to produce ACTH.
That ACTH then goes to the adrenal gland to stimulate the release of cortisone. So once we have an adequate level of cortisol within the bloodstream, we get a negative feedback back to that hypothalamus to say stop producing CRH and the pituitary gland will then stop producing ACTH and that's just the normal hypothalamic pituitary axis. Whereas with Cushing's disease, we mentioned the two different forms.
So here on the left you have the pituitary dependent form, and you can see here this represents a tumour in the pituitary gland. So this hypersecrees, ACTH. So you can see you will have an increased ACTH secretion here, which will stimulate both of these adrenal glands.
So they're both stimulated equally, and they will hypersecree cortisol. So, with the pituitary dependent form, you will have an increase in your cortisol level and also an increase in your ACTH level. Now, when our cortisol level is adequate, which it certainly will be, it will be more than adequate in these patients, it'll be high, that negative feedback goes back to the hypothalamus, but it's blocked.
It's not listening to it and it's just hypersecreting ACTH on its own, of its own accord. So regardless of the negative feedback loop, you will have a high ACTH and a high cortisol. Whereas the adrenal form here on the right, you can see the tumour down here on the adrenal gland.
So this is hypersecreting cortisol. So when you get that, the high level of cortisol, and negative feedback is sent back to the hypothalamus and the pituitary. And that will tell them to stop producing ACTH.
So with this form, you get a low ACTH and a high cortisol. And that's because this works independently from ACTH because it's just the tumour of the adrenal gland itself and it just carries on hyperseing regardless of what any of the feedback loop says. OK, so just briefly to talk about glucocorticoids to remind you of the importance of the mechanisms that they do in the body.
So glucocorticoids are the most diverse hormones that we have in the body, and it's the body's response to long term stress. They play a really important role in infection and also in chronic inflammation. Now we know with stress that we get an increase in our cortisol level, or steroid level, and The negative feedback control and the ACTH are maintained at higher levels when we are stressed, so it will override that negative feedback loop.
And also if we have any stimulation of the immune system, this can also interfere with the the mechanism of that feedback loop. And we also know that we may get a stress hyperglycemia with some patients. So our blood glucose is kept at a slightly higher level when we're stressed as well.
And cortisol helps to maintain that blood glucose volume. And it does this by promoting gluconogenesis within the liver. Now cortisol can also antagonise the effects of insulin, so we may see patients with insulin resistant diabetes.
And it also reduces the fat stores across the body and also the protein stores, except for in the liver. So if they can get a vacular hepatopathy with Cushing's disease. And it has a real catabolic effect on proteins, which is why we start to see muscular atrophy and muscular weakness across the patient's body.
And quite typically you'll see the muscle wastage and atrophy across the either side of the spine, the spine of the scapula, so the the top of the limbs, and also in the temporal region as well. And adipose tissue tends to redistribute itself, so it goes to the neck and also the abdomen, and that's what gives these patients this tabletop appearance. We also know that cortisol has anti-inflammatory properties, so we can mask certain conditions that you won't realise there until you start to treat the Cushing's disease, and one of the most common things that we see is a urinary tract infection, and we will talk about that in a little bit more depth later on.
So the pituitary dependent form makes up around 85% of patients, and it's most typically seen in smaller breed dogs, with 75% of these patients being less than 20 kg. And it is a functional adrenal, sorry, a functional pituitary tumour and it's most commonly seen in the past the stylis. Now they are really tiny tumours and commonly they're less than 3 millimetres in size, so really, really small.
So this makes it difficult to detect with advanced imaging, so only half the cases you may see a tumour. So it's literally a toss of a coin whether you go in to see it or not. And some pituitary tumours can slowly grow, and this can lead to a neurological sign or neurological signs, and we call this macro tumour syndrome when we start to see the neurological signs because of the growth of the tumour.
So, pituitary dependent is, we have a loss of that normal negative feedback response on the pituitary gland. The ACTH secretions can also fluctuate the same as the cortisol levels can, and that's important to remember when we're looking at our diagnosis because they're not always sky high, they can come back within the normal range and they will fluctuate on a daily basis, the same as it would naturally. And the pituitary dependent form will lead to having a high ACTH in the face of a high cortisol concentration, which is abnormal.
So we know that once the cortisol reaches an adequate level, it should send that negative feedback back to the hypothalamus, and then we shouldn't have any more ACTH. So we should have a low ACTH value if we have high cortisol, but with these cases, you will see it in both. OK, and then we have an adrenal cortical tumour.
So these again are functional tumours which make up about 15 to 20% of cases. And we know that the cortex is where cortisol is produced, so the cortex will work independently from the control of the pituitary. So that, that's where the tumour will be affecting and it's that cortex that will be hyper-secreting the cortisol.
And the other adrenal gland is likely to atrophy because it's just not needed. This one adrenal gland with the tumour, it's hypersecreting. The level is always adequate or high, so that the ACTH is never being produced and therefore that other adrenal gland is never being stimulated.
So quite often you will see a tumour on one side and an atrophied gland on the other. Now, the adrenal form tends to be more common in larger breed dogs, and there's two different forms which occur in equal frequency. So we have adrenocortical adenoma, which is benign, and then we have the cancerous form, which is the carcinoma, and that's malignant.
The carcinomas tend to be a little bit bigger. They can metastasize to the likes of the liver, the lungs or the kidneys, and they can also invade local structures such as the vena cava, and this can add in another complication if the patient were to go for surgery. Now we tend to see this in middle age to older patients, but it depends on what type of disease they have as to the signalment may alter slightly.
So the pituitary dependent we tend to see in smaller breed dogs, and it has a median age of 6 to 9 years. It's most commonly seen in smaller breeds, terriers, so the Yorkshire terrier, the Jack Russell terrier, Dachshunds and also seen in some poodles. And then the adrenal dependent form, we tend to see in older patients, this has a mean age of 11.
And this also is commonly seen in larger breed dogs, so your Labradors or your German shepherd dog. Now there's a massive array of clinical signs for Cushing's disease, and quite a lot of them will just look like normal signs of ageing. So quite often the owners will come in and this patient has had symptoms for months and months, but they just thought it was normal ageing signs, and it's only when they start to see some of the other signs, like the PUPD which is The sign that they commonly bring the patient in for because they're drinking a lot and they're urinating in the house all of a sudden, that you might start to be able to gain history from these patients and discover that it's been going on for quite some time.
So remember all the Ps, your PUPD, polyphasia, panin, and pot-bellied appearance. So your PUPD has been noted in almost all cases, and it's very noticeable. So if you don't have a patient with PUPD you can pretty much rule out hyperadrenal corticism.
You will also see muscular weakness and wastage from that metabolism of the protein, and because of that muscular weakness, you will get abdominal distention and that pendulous abdomen. And because of that, on abdominal palpation, it can be a little bit more rewarding because you can feel a lot more of the organs inside the abdomen, and you may feel a liver enlargement. The patient's likely to be lethargic and it may not, it may have a little bit of an exercise intolerance or it may not be able to tolerate the same level that it usually can.
And they may see myotonia, which is not very common, but you do see it every now and again. And this is just a persistent muscle contraction. So they may have a stiff gait, a bunny hop, and the muscles may be difficult to flex.
And alongside Cushing's disease, we tend to see hypertension. So unfortunately, hypertension does not resolve with the treatment of Cushing's disease. So you tend to see some of the signs that come along with hypertension like your end organ damage.
So this can affect your kidneys, your heart, your brain or your eyes. And you may also get glomerular damage which leads to proteinuria. And again, the proteinuria won't rectify with the treatment of Cushing's disease, so you'll need to treat the proteinuria separately.
And All of these signs can be quite vague, and a lot of the, the tests that we run for Cushing's disease are not overly specific. So our history and our clinical signs are very important when we're looking at trying to diagnose Cushing's disease, and we need to be they need to be highly suggestive of Cushing's before we pursue any further diagnostics. So we do tend to see a lot of skin changes, so they might have stretch marks, so they might get excessive bruising.
So if we take bloods from their neck or the leg, they may bruise quite a lot really easily. And that's because you get atrophy of the collagen and of the dermal connective tissue. You also get a thinning of the skin so you can quite commonly see the vessels through the skin like this image you can see in the corner.
And bilateral truncal and alopecia and also hair that doesn't grow back very quickly. So if you do clip the the leg or the neck for blood or an IV, quite often it will take a good while before that will grow back. And they can also get coons coumadones which are like blackheads in the skin and calcinosis cutis, which are little calcium deposits within the skin as well.
I tend to think we see this a little bit more with iatrogenic Cushing's disease. They're not massively common, but you will see them every now and again. And along with a high cortisol level, we get.
The typical slow wound healing, and it is noted that old scars can start to break down. However, this is very uncommon. And if you do have a bitch who is entire, you can get anestras, so they may not have a season for for months on end.
You can also see testicular atrophy, and that's because the cortisol level can interrupt the gonadotropic hormone. We know that steroids cause excess panin, and you can also see dyspnea due to a pulmonary thromboembolism. So these patients have an increase in their thrombocytes, their platelets, which makes them hypercoagulable.
So they are at a high risk of throwing a PTE. And then insulin resistant diabetes because our cortisol can antagonise the effects of insulin. Then we'll just briefly go over the macro tumour syndrome.
So if you do have a patient in who is showing neurological signs, this quite commonly can start to develop when you start to treat the patient. And that's just because of the removal of that negative feedback loop. The pituitary can then start to produce more ACTH which can in turn cause the tumour to grow slightly.
It can also cause edoema and an increase in the intracranial pressure. So they may present lethargic and dull, they may start to circle or head press. You can see blindness and you can also see seizures in these patients as well.
OK, so we think our patient is Cushingoid. What are we gonna do? So we need a full biochemistry, haematology and urinalysis.
So any patient with PUPD, we should definitely be taking a urinalysis and ideally it should be ultrasound guided cystocentesis. And on your full biochem you may see an increase in your ALP. So this is quite a common sign that we will see, and it makes up about 85 to 95% of cases, and it's likely to be 5 to 6 fold, the normal range.
However, it is not specific for Cushing's disease, so you should not use it to screen for for for Cushing's. And that's because it's not specific. So there are many other non-adrenal illnesses that can cause high ALP.
So we can't rely on that specifically to tell us that this is Cushing's disease. And there could be 5 to 15% of cases who don't have an increase in their ALP, so we shouldn't rely on it specifically. We may also see elevations in our cholesterol, or glucose, triglycerides, and our ALT.
And we know that with an increase in our cortisol, you get a stress leukogram on your on your haematology. And also thrombocytosis, so an increase in our platelet count, which makes these patients hypercoagulable. Now we talked about PUPD and how important it is in this wear cup, and along with PUPD we will tend to see a low urine specific gravity.
So if your patient has a specific gravity above 10/20, you can pretty much rule out Cushing's disease because they will all have a low USG. Proteinuria is common because of the damage to the glomerus that you might see and again it doesn't normalise with therapy, so you may need to treat that separately. And we do commonly see bacterial cystitis in about half the cases.
So that's why it's so important to always perform a cystocentesis on these patients and get some urine so that we can look at it. And the reason for a bacterial cystitis is because that muscular weakness that we've talked about will cause an over distended bladder. And with the over distended bladder, when the patient does urinate, it will fail to empty it each time.
So there's some residual urine in there each time which can start to grow bacteria. And also the cortisol levels can make it difficult for white blood cells to get into the bladder. So quite commonly you will see bacteria under the microscope with a lack of white blood cells.
And we know that cortisol has an anti-inflammatory effect, so therefore, it's likely to mask any of the symptoms of a urinary tract infection. And if we don't send it off a culture and start to treat it, then we may start to see those side effects occurring as we treat the Cushing's disease. OK.
So an important take home message is do not test for hyperadrenal corticism in severely ill patients. So even if they're just moderately severe, moderately ill. And that's because we produce cortisol at a higher level when we're stressed or when we're ill.
So if you test for Cushing's disease in a really sick patient, you can get a false positive, and that's because the cortisol level is high because they're sick. So what we need to do is just send them home, treat that condition, whatever it is they're tackling, get them back in 2 to 4 weeks. If we still think they're Cushing weed, then you can start to look at testing the adrenals then.
And then if you are convinced this patient has Cushing's disease, you've now got the wonderful task of endocrine testing for it, which is a minefield in itself. So, most common tests that we run an ACTH stimulation test. So this is easy and it's cheap to do in-house and you only need to wait one hour, so it's really it's commonly used for that reason.
So for this you would have a high pre and a high post cortisol concentration. Before and after giving the IV ACTH and the dose you can give 250 mcg per dog, or 5 mcg per kilo IV. And there is quite often a shortage of synactin, so you can freeze what's left in the bottle, put them in small syringes or little aloquats, and then just defrost them and it's absolutely as effective.
It's absolutely fine to do. So keep, keep hold of your son actin. Don't throw it away if you don't use the whole, the whole bottle.
Now this has a sensitivity of 60 to 85% for diagnosing pituitary dependent Cushing's and 60% for adrenal tumours. So It also has a specificity of 85% to 95% to 90%. So, with a sensitivity that low, there could be up to 40% of patients with hyperadrenal corticism walking round, and yet they will have an absolutely normal ACTH.
So we need to bear that in mind when we're looking at interpreting these results and when we're choosing what tests that we're gonna, we're gonna run. Should we always be doing an ACTH as a firsthand test? It does not differentiate between pituitary and adrenal form.
And it, it, it can be used to diagnose iatrogenic, Cushing's disease. And if that is what the patient is suffering with, then it will present like an Addisonian patient. So it will have pre and post cortisol levels will both be low.
And that's because we're supplementing that steroid so the adrenal glands don't need to do anything and the ACTH doesn't need to be produced because our levels are perfectly adequate with the PEDs that we're we're providing. So you can see here, iatrogenic Cushing's is at the bottom. So low baseline and low post, so pre and post both low.
So that's either Cushing's or iatrogenic, iatrogenic Cushing's, sorry, Addison's or iatrogenic Cushing's. And then you have your normal control here. And then spontaneous Cushing's, it's already high, and then you give the ACTH it provides further stimulation and it will whiz up and be really, really high up here.
So that is indicative of Cushing's disease on your ACTH stimulation test. Now another test that we can do is a low dose dexamethasone suppression test. And this can be more reliable than an ACTH stim, and it's used to confirm Cushing's disease.
So it has a high sensitivity of 90 to 95% of pituitary dependent hyperadrenal corticism and nearly 100% for adrenal Cushing's disease. Now this can help differentiate between PDH and adrenal form, but the specificity again is very low. So this can be as low as 40 to 50%.
And we need to remember these things when we're looking at what tests to run and when we're interpreting them as well. So 65% of pituitary dependent Cushing's will suppress at 3 hours and then they'll escape back again at 8 and it'll be high again at 8. Whereas very few adrenal tumours will suppress a 3, and we'll show you a little table at the moment.
And if patients do not have a have Cushing's disease, then they will be suppressed at both 3 and 8. If you give them small amounts of dexamethasone, some steroids, it will suppress them at both of these tests, 3 and 8 hours. So you can see here again, hypoadria course is more iatrogenic, it's just a flat line at the bottom.
This black line here is the normal value, so here's your pre. We've given some low dose dexamethasone, and it's suppressed here at 3 hours, and then it continues to be suppressed at 8. Whereas with the pituitary form, we've given some dexamethasone, it's suppressed at 3 and then it's escaped.
So it's, it's increased again. It's hypersecreting from the pituitary gland and it's on the increase again, so it's high. And then here, the adrenal form, it won't suppress or it's unlikely to suppress very much at 3 and the same at 8, so it's just high at both.
Now there have been some studies or some research that have shown with the pituitary form, this triangle here, where it will go down and then back up again and escape at 8 can be the other way around. So it could go higher at 3 and then back suppressed at 8. So either way, whether the, whether it's going up or down, it can be indicative of pituitary dependent hyperadrenal corticism.
Now, there are some other tests that we can do, and a high dose dexamethasone suppression test has been used occasionally to help differentiate between the two. But often given a higher dose of dexamethasone still doesn't increase that much of the specificity of this of this test. So in this case, if we haven't got much of a response from the low dose deck, you'd be much better off to just go down the adrenal imaging route.
And we can also perform endogenous ACTH which we'll discuss on the next slide. And remember we took urine earlier on, so urine corticoid and creatinine ratio or UCCR is quite useful to exclude Cushing's disease. And that's because it has a high sensitivity of nearly 100%.
So if we do a urine sample and there's no cortisol present, so it's negative for cortisol, we can pretty much rule out Cushing's disease. Whereas if you have a positive result, so there is cortisol, just discard it. So it's It's too common to get, we can get too many false positives because stress can cause an increase in your cortisol, which will send it into your urine, and many other non-adrenal illnesses cause an increase in your cortisol.
So you can also have a positive result from them as well. So if you do have a positive result, just discard it, but if it's negative, then you can rule out Cushing's disease. And in order to minimise the stress and get it as accurate as you can, you should ask the owners to collect as a free catch sample at home to try and minimise as much stress as we can.
And again, this test is not something that can differentiate between the two different forms, it's just simply a yes or a no. Now we can look at endogenous ACTH, which is quite a useful test to run. So the measurement of basal endogenous ACTH is of little value when screening for adrenal cor hyperadrenal corticism, but it is valuable in determining, determining which one we're looking at.
So we know if we have a pituitary dependent tumour, it hypersecs ACTH so we will have a high ACTH if it's pituitary dependent. Whereas we know that our adrenal tumours hypersecrete cortisol without any interaction with ACTH at all. So they work independently and they are not stimulated by the pituitary or any ACTTH production.
So for those ones, we're likely to have a low ACTH and that's how you can differentiate between the two. Now these can be tricky to do because they do need to be frozen samples, but once you've done one or two, they are quite easy. You just need to phone your lab.
They all have slightly different protocols. Phone your lab, they will send out a package which is just like a little freezer block that you can put your blood tubes in and then you send them back frozen with their courier. So it is really easy to do.
You just need to make sure that you have the correct transport method. And if you phone your lab, they'll post it out to you pretty quickly. OK, so let's talk about imaging.
So if you perform radiographs, you might be likely to see a hepatomegaly, and it may be useful for any pulmonary changes. So how is the patient showing any signs of a pulmonary thromboembolism, or we can do a met check on the, on the chest. Ultrasound is the most useful form of advanced imaging, and this can help differentiate between the pituitary and the adrenal form.
So you'll get unilateral adrenal mass with . Atrophy of the other adrenal gland, if you have the adrenal form, whereas if it's pituitary, you may see bilateral adrenomegaly, so they'll, they're likely to both be big. However, this 25% of cases can have normal sized adrenal glands, and remember that the normal ranges of adrenal size can vary from patient to patient.
So you do need a skilled ultrasonographer, ultrasonographer for scanning adrenal glands. Ultrasound is also really useful for assessing for signs of malignancy. So it allows you to check that liver, it allows you to check the kidneys and the rest of the abdomen to check if there's any other signs of spread if you are looking at a carcinoma.
And you can do MRI or CT to look at pituitary masses for the pituitary dependent form. However, MRI has been shown to be superior over CT because it will detect smaller masses of less than 3 millimetres, which these patients commonly are less than 3 millimetres. So these are some images of a CT.
So the top two images you can see a pituitary tumour there, just in the circle and next to the two arrows. And then down at the bottom you can see it's pointing towards an adrenal tumour. OK.
So how are we gonna treat our Cushing's disease once we know that that's our diagnosis? So one of the first questions, do we need to immediately treat every Cushingoid dog? So we're likely to have an owner coming into us saying, my dog has typical signs of ageing, they're not that .
They're not too bad, but maybe we have some PUPD and that's the symptom that I'm struggling with because they're urinating a lot in the house. What do they want us to do? They want us to treat the patient so the signs go away.
Will they always go away? Not necessarily. So we need to be honest with the owner.
We need to have that discussion. Treatment of hyperadrenal corticism is never benign, and we need to be aware of the side effects that the drugs can cause. And it has been noted that they can cause haemorrhage of the adrenal gland and very rarely it can, it could also rupture the adrenal gland.
However, that is luckily very rare. It's also quite an expensive drug trial ofta, and also all the follow-up blood tests, lifelong, are expensive. So we need to be realistic and especially in those patients who are older, are they, do they want to go for treatment if it won't necessarily fix the hypertension, the proteinuria, and it may not get rid of some of the clinical signs.
If they do want to go for treatment, absolutely great. So, in order to treat these patients, there's two different things that we can do. So the pituitary dependent, Cushing's can be treated medically with Trilaine or vetarol, and it's a very effective drug and it works for about 80% of cases.
And it inhibits the 3 beta hydroxysteroid dehydrogenase in the adrenal cortex. Now the data sheet says that we should give doses of 2 makes per kg orally once a day. However, there has been some research that's shown trilasta reaches its peak concentration.
Anything from 2 hours after administration. And then the cortisol concentrations were suppressed around 12 hours and completely metabolised within 10 to 18 hours. So that's quite different from what the data sheet is telling us.
So some clinicians will recommend 0.5 to 1 mg per kg orally twice a day rather than once. And they found that this is more effective and it may cause fewer side effects with a longer survival time.
And some people, some patients will even require it 3 times a day, but treat each each patient individually and see how they get on with the treatment that you administer. Now, the side effects that you may see, you may tip them into hypoadrenal corticism, so we may suppress it a little bit too much and they will get the the typical signs of Addison's disease. So lethargy, vomiting, high sodium potassium ratio, maybe some GI signs, diarrhoea, very similar to your Addisonian patient that may present.
And trilasan just decreases the plasma cortisol and increases the ACTH secretion. And as we mentioned earlier, this can cause growth of the pituitary tumour. Triistine can also cause adrenomegaly.
So if you're thinking of putting the patient on rilesine before doing any imaging. It's definitely worth holding off because it will cause adrenomegaly, and then that will make your diagnostic pathway very difficult. So if you're trying to determine whether it's pituitary or adrenal form, it's going to be difficult for you to tell because both adrenal glands are now going to be enlarged and you won't be able to image it as effectively.
So just hold off. They've probably had Cushing's disease for some time. You don't need to start it immediately, just do your imaging first and then look at popping the patient on Trista.
And in some very rare cases, it can induce adrenal cortical necrosis. So it's definitely not a benign drug by any means. Now, once we monitor these patients, sorry, once we start the treatment, we should give rilesta and then we should see them back after 10 to 15 days, and then about a month, 3 months, and then ideally, every 3 to 6 months afterwards.
Now, when we're looking at performing ACTH stimulation tests, the data sheets recommends to do a 4 to 6 hours post pill. However, we've just discussed that the studies have shown that the peak concentration is anywhere around 2. So you can start your ACTH stimulation test to coincide with the peak, so 2 to 4 hours post pill rather than 4 to 6.
And one of the important things that you can do is just make a note on your clinical records of when you did take the first sample, because if it is 3 hours post pill. Then next time you come in, you should do 3 hours post pill and the time after that should be 3 hours post pill. Just for consistency to make sure any peaks and troughs or any changes and fluctuations in your results is not because you're taking a sample after 2 hours, then a different one at 6, then a different one at 3.
It's important to be consistent and try and get that sample on time as much as we can. Now, when we're looking at monitoring and interpreting our results once the patient's under therapy. If the clinical signs are well controlled with the owner, they come in, they're happy, and the ACTH indicates a good cortisol level or even if it's slightly high, then we don't need to necessarily change the dose.
And the most important thing here is that the owner is happy and that those symptoms are being controlled. And we need to remember that we treat the patient rather than treating the test results necessarily. And if clinical signs are not controlled, and the ACTH indicates good control, then you can consider increasing the frequency of the medication.
Whereas if the clinical signs are not controlled at all, and the ACTH the ACTH stimulation test indicates that your cortisol is still high, you can increase the dose by 25 to 50% and then retest them again shortly afterwards, maybe 2 to 4 weeks later. Now you can also do a trough cortisol. And this is just a pre-pill cortisol.
So it was found to be in better agreement with an owner-based scoring scheme in one study. And good clinical control tends to be associated with a pre-pill concentration of 40 to 139 nanoms per litre. So this can be looked at as the target range that we aim for when we're looking at a trough cortisol.
Now urine is really, really useful when we're looking at Cushing's disease and you can use urine specific gravity to To look at how well the patient is is controlled. So a good treatment response should have USG over 1020, so the patient should no longer be PUPD. It should be concentrating its urine and going at normal frequencies throughout the day.
So if you have a 1020 or aboveSG, then that indicates that we may have good control. And in this scenario, your ACTH results are used to determine the trial listing dosage, and your urine specific gravity can be used to determine the frequency. So one quite useful and very easy and cheap thing to do is ask your owner to collect 3 urine samples at different parts of the day, bring them in to the lab.
We can look at your and specific gravity at all 3, and if they just note down the times that they've been given. Sorry, the times that they've collected the urine. Look at the USG of all three of those tests.
If all three are nicely concentrated and are above 1020, that tells us that those cortisol levels are an adequate level throughout most of the day, because our kidneys are concentrating that urine and we're not PEPD. The symptoms and the cortisol seem to be well controlled. Whereas if you have maybe two good USGs and then one is really dilute, that tells us that maybe our drug is wearing off a little bit soon and we may need to increase the frequency.
So, really useful thing that we can do, it's easy, it's cheap and it's quick and we can do it in-house, so. Bear that one in mind. And then treatment of the adrenal dependent Cushing's disease, providing there's no invasion into the surrounding structures like the vena cava, or there's no metastatic spread, then a complete surgical removal does carry the best prognosis.
So this is a highly specialised procedure. So it should definitely be performed by a specialist surgeon in a specialist referral hospital and in a place that has an intensive care unit, because the post-op complications are very high because of a number of things that come along with a number of complications that come along with this condition, including thrombosis. So they're really hypercoagulable and they're at high risk of throwing a clot or having a bleed postoperatively.
So patients with adrenal tumours that survive the surgery are likely to live anything between 2 to 4 years. However, if it is a carcinoma, unfortunately they tend to do a lot worse and they can often have a life expectancy less than 1 year. Now, not everybody will go for surgery.
We've discussed that this, the adrenal form is more likely to be seen in older patients. Will an owner put an 11 year old dog through a big surgery that carries massive risks? Not always.
So in that case, you can just pop them on trial of staying as an alternative if they don't elect for surgery. And if you do have a patient with neurological signs from macro tumour syndrome, radiation therapy is also an option. Now if the patient, if the owner does go for surgery, we need to be aware of some anaesthetic risks because an untreated cushingly patient carries a lot of anaesthetic risks.
So we've talked about muscular weakness, so this will also weaken our respiratory muscles, so we can have a poor respiratory function. We can also have our hepatic function is affected, so we need to bear that in mind when we're looking at what drugs we're gonna pre-medicate these patients with. They're very high risk of.
Of pulmonary thromboembolism because they're hypercoagulable. And they may also have poor hemostasis because they have a decrease in their vascular tone. And then postoperatively, they may have delayed wound healing because of that excess of cortisol level.
And they absolutely need to be in an intensive care or a high dependency unit because these guys carry mortality rates of 20 to 30%, which is really high. OK, so prognosis, depending on the type of of hyperadrenal corticism that you have, so patients with the adrenal dependent Cushing's that survived the surgery may live for around 3 years on average. Although if it is a carcinoma, unfortunately it carries a worse prognosis and they may only live less than one year.
Whereas if you have pituitary depends and Cushing's, they may survive for a mean age of around 3 years. And if you've caught it at an earlier age and diagnosed it earlier, then they have a much better chance of having a significantly longer outcome. And there are some complications that the patients may also develop.
And some of these include diabetes, insulin resistant diabetes, chronic kidney disease because of that glomerullar damage and also macro tumour syndrome if the tumour does grow and cause neurological signs. OK, so that's all from me. I hope you've enjoyed it and thank you very much for listening.