Hello, thank you so much for choosing to watch this webinar. My name's Sarah Caney. I'm a UK based specialist in feline medicine.
And the topic for this webinar is diagnosis of polydipsia in cats. So I'm going to present a few cases through this session and er use those as opportunities to explain how I approach diagnosis of increased thirst in cats. The first case I'd like to introduce you to is a cat called Percy Plod, and a cat I will always remember and also always remember trying my hardest not to call the owner Mrs.
Plod, which was very much not her name, but this is Percy, we can see here, a 5 year old male neutered domestic shorthair who'd been rescued by them about 18 months previously and actually since being rehomed, had had quite severe but waxing and waning skin disease. So actually he was presented to dermatology colleagues of mine because of this severe pruritic skin disease, which was quite generalised, but his face in particular was especially pruritic. But he also had some medical issues which led to my involvement, and those included having diarrhoea, sometimes with fresh blood present.
He was very polyphagic, often, and also, pertinent to this presentation, he was polydipsic and so drinking between 200 and 400 mL per day in spite of eating a wet diet. So polydipsia is clearly just one of multiple complaints with Percy, but it gives us an opportunity to just start to look at polydipsia, and for a start as well, consider, well, how do we define polydipsia. So what is the, the sort of textbook definition of this and how would I define it?
So if you look in a textbook often you'll see numbers included in in reference to answering this question. So, perhaps more than 50 or more than 100 mL per kilo of body weight per day are cited as cutoffs for an abnormal thirst. But there are so many things that can affect how much a cat drinks, and diet is one of these.
I already mentioned that Percy was eating wet food. Clearly cats eating a dry diet will need to drink more voluntarily than cats eating a wet diet, where they may get, if they have, you know, good health, all of their requirements for fluids, just from the food alone. But other things that can affect their fluid requirements would include the cat's activity levels, and potentially illnesses as we're gonna come on and talk about through this presentation.
So in the real world, I think actually it's probably more helpful to think of a definition of polydipsia as being more than is considered normal for my cats. So just from an owner perspective, if they spot a change and they think it's a change, which is significant or noticeable to them, then I think that's a good enough definition of polydipsia. Beyond that, we can potentially measure water consumption.
From a diagnosis of polydipsia as a clinical sign, there's probably very limited benefit to us actually measuring water intake, but the magnitude of that polydipsia, so the severity of the polydipsia, can be helpful in terms of. Differential diagnoses. So for example, cats that are diabetic, diabetes mellitus tend to be markedly polydipsic, whereas cats with hyperthyroidism can have more of a a small, a subtle increase in their thirst.
The owners just may spot that they are at the water bowl a little bit more frequently than they would have been in the past. Measuring water consumption can be of some value from a monitoring perspective, particularly in diabetic cats, where even actually if you have a multi-animal household, cats and dogs, sometimes it can be helpful to actually monitor how much how much water is consumed within the home. Obviously if you're, if it's a single cat and it's indoor only, then it's especially easy.
But even in the multi-animal households, it can be helpful, still to look at total water consumption because any change, particularly any reduction in that total water consumption, may well relate to improved diabetic control, for example, if you're talking about a diabetic cat. And an example of where monitoring water consumption was helpful, in a diabetic cat is, is this one, Toots, a 13 year old female neutered domestic shorthair. Toots' owner in the background there, an elderly gentleman who very much loved his cat.
And so when I asked him if he could measure how much water Toots was. When we started to stabilise the diabetes, he was extremely obliging. Depending on the size of your screen, you may or may not be able to read the numbers that I'm showing here, but each of these lines is 12 hours of water consumption.
So you need to add 2 together to get 24 hour water consumption. And at the start, Toots's water consumption was typically around about 400 mLs, sometimes a little bit more, sometimes a little bit less. And then with time, as the diabetes came under control, that very much dropped.
So the lower figures, water consumption now more like 120 mL per 24 hours. Toots did have some concurrent chronic kidney disease, which meant that even though she was receiving a wet diet, her, her thirst never completely disappeared as it were, but you can see the profound impact of good diabetic control in terms of the polydipsia. So back to the presenting sign though of polydipsia, what's a sensible approach in terms of diagnosis of these cases?
So we've talked a little bit about confirming the polydipsia and measuring the amount of water consumption, and there may be some situations where that that's more helpful than others, so hence the brackets here. But the things that are definitely going to be helpful are going to be the history and the physical examination, really trying to find as many other clues as we possibly can, which will help to guide us towards the cause of this cat's thirst and therefore the answer to its problems. So what are our differential diagnoses and therefore what tests are going to be most helpful in confirming or ruling out these differentials.
Undoubtedly though, the urinalysis is the most important of our initial diagnostics, and that is something that can be done in the absence of the cat. So if an owner reports polydipsia, then asking them, to collect. A urine sample from the cat at home may well be an appropriate next step, particularly if that cat hasn't got a big enough bladder to get a cysto sample from in the consulting room there and then, or if the owner is speaking to you in person over the phone without the cats being present.
And blood tests often are needed as well to confirm the cause of the polydipsia, and, the choice of these different tests is going to depend on the individual, so it may start with what I would, I've referred to as minimum database, so our routine haematology biochemistry, but clearly there may be additional tests that are needed or which we may choose to include from the start, such as a T4 for hyperthyroidism. So I've referenced urinalysis and I, I therefore think it's worth spending just a little bit of time talking about urine collection in cats and the different methodologies and some of the pros and cons, and how we do these different things. So free catch.
Is where we have typically a non-absorbent cat litter or an empty litter tray, and the cat, then when it urinates, we, we are able to collect the samples. So it's a a sort of less clean if you like, sample, but, it can be something that often is done at home. Cystocentesis obviously involves us putting a needle into the bladder.
We'll talk through the technique of that in in just a moment. Occasionally I have had some owners where the cat very, predictably, routinely, for example, goes and, and urinates after having its breakfast, and the owner somehow is able to, you know, insert a some sort of receptacle to collect a sample midstream. You know, I've probably had a handful of owners over the years that have been able to do that.
And last but not generally used, in the polydipsic scenario is a catheter collected sample. I think it's perfectly acceptable and appropriate to use a catheter, urethral catheter into the bladder to collect a urine sample if we are placing a catheter for other reasons. For example, our blocked cats, cats we're doing low urinary tract investigations on, for example, contrast imaging, etc.
But we wouldn't routinely place a catheter just to collect that urine sample. So cystocentesis, I'll talk about the technique in just a moment, but some of the pros and cons here, so, advantages are, it's generally a straightforward technique. Most cats actually tolerate a systo better than they tolerate a blood sample.
Your target is bigger than a blood vessel typically as well. And so often it is a sort of quick, easy way to get a urine sample from a cat, and it's a clean sample, so it's ideal for all analysis, including bacteriology. And, therefore often helps us to, get that ideal sample really as quickly as possible.
Some of the disadvantages would include, obviously it is a procedure involves some restraints, some handling, some cats are less amenable to that than others. It's definitely tricky if the bladder is small or the cat is very tense, or if the cat is very large. So overweight cats with small bladders are probably the hardest cats because.
It's harder to feel the bladder, to know how full it is, and also to stabilise it, for that sampling. And we should, of course, be, charging the client something for the the techniques that the, the skill involved, so there's a little bit more cost from an owner perspective in terms of getting that cystocentesis urine sample. It's quite common for our cysto sample to have a small amount of blood contamination, which is usually only evident on dipstick or microscopy, not visibly evident, but this is an example of where, where it really was visibly evident, and this is.
2 samples from the same cat on the same day. This is one of my kidney cases and it came in for a routine monitoring assessment, and the owner would always bring in very helpfully a free catch sample that she got from the cat overnight at home. And that's the sample on the left, which you can see looks grossly quite normal.
But, I did, where possible, prefer to get a cysto sample, for analysis, and, the cysto sample on the right hand side you can see, unfortunately, I obviously twanged a vessel either going in or coming out of the bladder, and it's just got that very slight rose tint to it. And the reason for showing it here is because when it comes to proteinuria assessment, if we can actually see a visible discoloration of that urine, which we can hear, although it is mild, then that's likely to have an impact on our urine protein to creatinine ratio. So if we're looking at proteinuria specifically, that iatrogenic blood contamination.
Is likely to impact it and not by a great deal in this case, in fact, I did get the lab to run both samples, and I think the UPC, the one on the left, was was about 0.2, and it was about 0.3 for the one on, on the right.
So it's a small impact, but nonetheless, it it there is an impact and and depending on the severity of that hematuria, that could make a very definite impact on our decision making. So on this particular occasion, the better sample of proteinuria was actually the owner home collected free catch sample. So how do we do a cystocentesis in cats?
So, my first tip is to have a longer needle than you would for a blood test. So a 1 inch or 1.5 inch needle, is a good length for a cisto and a cat.
I used to use a 5 mil syringe. My next tip is really to, for a conscious cat, only do this if you can palpate the bladder. Actually for anaesthetized or sedated cats also, but it's obviously much easier to palpate the bladder when they are, sleepy, er, rather than.
And they're fully conscious, but if they're, when they're fully conscious, you can't feel the bladder or you can't sort of isolate the bladder comfortably. I would not recommend that you do attempt a Cysto because there's just more of a risk of trauma, than a successful collection of that sample. And the ideal positioning of the cat for sampling really depends a little bit on the cat, the size of the bladder, and, er, also, perhaps what help has available to you er as well.
Ideally, it should be the position that the cat is most relaxed in. So less tense, less stressed, so that you can feel the bladder most easily, but also that you can access it. So with small bladders, a lateral sister in a, in a, a wake cat can be challenging because the back legs often are, are sort of overlying where you might want to insert your needle.
So often, and I'll show pictures of all of these different positions in a moment, I would say in a conscious cat, I find it a sort of ventral systems, where the cat's lying in dorsal recumbency and I'm, my needle is going in through the the ventrum, is the easiest place because that's between the back legs and so, it's, it's the easiest place to access. And hence this comment at the bottom of the slide where sometimes Depending again on the cat, it can be helpful to be a bit greedy with your colleagues and have one person gently holding the front legs and sort of tickling under the cat's chin, and the other person holding one, back leg in each hand so that the cat is not actively aggressively sort of restrained, but just gently sort of, gently restrained whilst you then, feel the bladder with the cat lying on its back. Once you're in whatever position you choose to be in, there's no need to clip the fur or aseptically prepare that area, but you want to just make sure that you can palpate the bladder and stabilise the bladder.
And then once you're happy that you have, stabilised the bladder, so it's not moving around, you then want to remove the the needle guard from that, the needle, which is on your 5 mil syringe and. With that needle perpendicular to the skin, gently place that needle onto the skin, so the cat has an awareness of it before you pass the needle completely through the skin, all the way to the hub, and then, you can usually just withdraw urine, aspirate your sample. And then once you've got enough sample in your syringe, you can just release any sort of pressure you might have on that bladder gently as you withdraw, and er and then you've got your sample which you can put it into your container.
So a few pictures just to illustrate this procedure. This is a picture that Danielle Gun more kindly, allows me to use and actually makes this look, I think this, this, standing position look more tricky than in reality it is, but it's often difficult. Get photos of these sorts of procedures.
The reason it makes it, I think makes it look a little bit trickier is that this person is unusually left-handed, and the cat is being gently held, perfectly held by the nurse here, but in an orientation that would be easier if this person was right-handed, because you can see their hands are sort of crossed over. So their right hand is palpating the bladder and, and sort of stabilising it and the left hand is holding the syringe, but they've got hands crossed over. Because of their left-handedness and the cat facing to the left, it would be easier for this person if the cat was facing the other way.
In this next example, we've got an anaesthetized cat, so very, very relaxed, lying on its back, and this is me now feeling that the cat's bladder and I'm pushing the the cat's bladder cordially, so it's stabilised between my left hand, and the pelvis. So it's very still and then my needle has been placed just over the, you know, perpendicular skin, over the top of that area and then gone through and aspirating a sample. In a conscious cat, the equivalent of this I often would do is shown here.
So I often actually get my nurse colleague to to sit on the chair in the consulting room, have a comfy bed on their lap, and then the cat is sort of blobbed onto the The nurse's lap and the nurse is sort of giving the cat a little bit of a cuddle, a little bit of a distraction head end, holding the front legs comfortably, and most cats will actually not need any restraint of their back legs, they're just sort of naturally sit in this relaxed position. I can then. Feel between the, the, the cat's legs and the ventral abdomen, feel the bladder, stabilise it between my hand again, pushing it downwards towards the, the pelvis to keep it still, and then place my needle on top and aspirate the sample.
Unfortunately, I, I just can't take a photo of myself doing this procedure and and never enough people around to to capture on film for me. This is a cat having a lateral cysto, and this is a sedated cat. It's a very, very relaxed and this cat, Cleo had a very small bladder, so you'll see it does take a little bit of time and a little bit of a, a jiggle to get the sample, but I'm feeling the bladder, it's resting on the fingers of my left hand.
With the thumb of my left hand at the pole of the bladder and just sort of stabilising it. And then I place my needle on the skin, I slide through. I immediately get some urine, but because the bladder is tiny, it sort of comes to a bit of a halt and I need to just have a little bit of a wiggle around to to get more flow of urine and sort of fill up my syringe.
And then once I've filled up my syringe, I've got enough, I then can just relax any hold on the bladder, withdraw the needle and er I've got my sample ready for analysis. And this is just a still of a similar example of what's happening. So again, anaesthetized cat here a very still bladder resting on the fingers of my left hand, thumb of my left hand in front of the pole, the bladder, needle, perpendicular to the skin over the top, going down and collecting the sample.
There is on my website, if you look on vetprofessionals.com at the helpful info menu, below that, there is, there are various sections. The free downloads are, technical guides, they're PDF documents typically, but the video tutorials has got some video.
And there are some narrated videos I've removed the narration for for this one, for this presentation, but, this is one of my cats, who's a bit overweight as you can see, but, came in for some routine health monitoring. So we did blood pressure, blood sample and cisto, and this is me talking through the procedure, and so palpating the bladder, making sure that I'm comfortable. I can feel the bladder.
And then if I just skip a bit further forward, oops see in the video. Apologies, that's it, yep. Then you'll see, I get to the point of actually doing the samples.
So, feel the bladder, make sure you're comfortable and confident feeling the bladder, and then stabilise the bladder, put the needle on the skin, then slide it all the way through. And then aspirate the sample and with him, he did have quite a full bladder, so it's pretty straightforward getting that sample so you can see. It's a difficult video to really explain because you need to be feeling it, but that's his sample, two cameras in the room, he slightly different angles.
Now many of you will be very adept with an ultrasound probe as well. And so I, I gather it's, it's often more routine now for, particularly the new graduates that I work with to have been taught CISO . Ultrasound guidance and certainly for large cats, fat cats and cats with small bladders, which is many cats with urinary tract disease, then ultrasound guidance really can be extremely helpful in facilitating that.
And the bladder is one of the easiest things to see on an ultrasound because the black of the the fluid, the urine within it shows up very easily on the scan. And this image here, this cat actually has some free fluid within the abdomen as well. So below the bladder wall, you can see there's a little bit of fluid there.
And often that's it's a good place in the abdomen to actually look for small amounts of of acidic fluid, if you're considering that as a possibility in your medical workup. You don't need to clip or prepare the skin again, just a little bit of, surgical spirit, and then, image of the bladder and, sample the cat. Free catch urine sampling involves using non-absorbent cat litter in a tray.
There are various commercial, options available for this, so things like cat core, which are widely used for plastic beads. Also a kit for cat is the hydrophobic sand, which is available. I also know owners that have found success using just a sheet of bubble wrap in the cat's litter tray.
Or, chopped up plastic bags, aquarium gravel, all sorts of things that are possible, essentially anything that is non-absorbent and ideally that is clean or sterilised, where at all possible, particularly if you want to do bacteriology on the free catch sample. So advantages of the, the free catch is that, again, it's often straightforward, particularly for older cats or cats with urinary disease. They will use a litter tray, with non-absorbent litter in it, whereas, perhaps, you know, younger cats may be a little bit harder to persuade, to do that.
The sample that you get is, I think, pretty acceptable for most of our urinalysis and and can be used for all of the urinalysis we would normally do. We just need to interpret our findings perhaps a little bit differently. So for example, be.
That, because the urine will wash through the urethra as well and into the litter tray, which is not sterile, there is more of a possibility of bacterial contamination, so small numbers or of mixed bacteria may be found on culture. Also the, the protein estimation can be influenced as well by free catch versus cisto. Also, some cats, can be quite tricky to get a free catch sample from.
They they they may just refuse to use that litter tray, so that could be a problem. And so it, it's, you know, there are, there are advantages, there are disadvantages, but certainly from my perspective, I would say, it's a very good starting point for our urine sample. For some cats, it's the best way to get all of our samples, depending on the cat.
And it's temperament, etc. And, it still can be useful even for when you're looking for evidence of bacterial infection. If you've got a profuse pure growth of bacteria, then that is significant.
So back to our polydipsy cat, the most important things really here, initially at least, are to look at the concentration of the urine specific gravity, and also to do a dipstick, in particular, thinking of, of glucose with diabetes already mentioned as an important cause of polydipsy in cats, and then there may be other tests that are indicated beyond that, for example, in a diabetic cat, often I would want to do a urine culture where possible as well. Our in-house urinalysis, just a few reminders really in, in particular, that we should use, a refractometer to assess specific gravity. The dipsticks are designed for human urine, they are definitely no good for assessing USG.
In our own patients and also dipsticks, we often use dipsticks that have multiple pads on them. Many of these pads are actually not very helpful when it comes to our urine sample felines especially, so for example, the leukocytes, and often the the nitrite pads will be positive just with all cat urine and do not mean anything. They are not an indicator of infection on their own.
Protein, it's obviously a, a, a spot reading from a dipstick, so it's not as accurate an indicator of of proteinuria as a urine protein to creatinine ratio would be. From a ketone perspective, dipsticks only detect the aceto acetate ketones. They don't detect the beta hydroxybuyrate ketones, so .
Be less sensitive for identification of of ketosis in cats. But the good news is they are good for picking up presence of blood, haemoglobin, myoglobin, and glucose and glucose again, definitely something we're keen to look at in our polydipsy cats. You're in specific gravity, also really important to look at in the context of, of our polydipsy cat.
We want to know what is its concentrating ability like. And in, in terms of our normal interpretation of USG, a normal result is for most cats greater than 1040, certainly, greater than. 35, abnormal, of course, is the opposite, so less than 1035 is generally the, the cutoff that we would use, and common causes of a reduced USG include chronic kidney disease, hyperthyroidism, diabetes malls, further investigations obviously required to confirm that.
I have put here that I consider really a USG 1035 to 1040 to be borderline, so I, I, I do generally want to have a closer look at these cats, certainly not let them completely off my radar, reassess them in the next six months if at all possible, because clearly, especially for the older cats here, having routine preventative healthcare screening. Including a urinalysis, they will drift down, often quite gently before they reach that 10:35 cut off, but having a result of, you know, 10:35, 10:38, is a cat that I, I definitely don't want to lose to follow up. I want to sort of make sure that that cat stays, under my radar, if at all possible.
So in summary, normal cats USG generally 1040 to 1090 and . If the cutoff of 10:35 is the one you typically will see in a textbook, but certainly 10 140 and above is is typical and that is, you know, a cat with a normal concentrating ability and and an appropriate thirst if it if it is, in the owner's perception drinking more than they would expect. So that might include, for example, cats that have moved on to a dry diet where they clearly do need to drink more, because they're no longer getting water in their food.
So again, back to our polydipsy cat, let's think about differential diagnoses for polydipsia now. So what are some important causes? Well, there are lots of things that are on the list, but the most important are the two at the top, actually.
So endocrine and renal causes of polydipsia account for the majority of our polydipsy cats. Other things that are on the list do include some cats with liver disease, some electrolyte disorders, which I'll I'll reference slightly later as well. Iatrogenic, so that might include the cat that's on rozamide for a for a heart disease that it's on a diuretic, so it'll be drinking more, the cat that .
Perhaps is having a liquid diet because it has an esophageal stricture, so you're just sort of like forcing it to take in more fluids as well. That might come under that category. We've also got pyometra is a, not very common thing we see in cats because most of our patients are neutered, but that can can be associated with polydipsia, as, as is the case in dogs as well.
Psychogenic got a big question mark at the bottom there. As to whether or not that that exists in cats, but you can see it's quite a long list overall of differential diagnoses, but the majority very much fall into the top two categories. So from an endocrine perspective, the, the big ones to think about diabetes and hyperthyroidism in terms of prevalence.
Hyperthyroidism affects 1 in 10 older cats, diabetes, has a much lower prevalence, but tends to have a more dramatic polydipsia, hence I've put it at the top here. And the other endocrinopathies that can all be associated with polygypsy but are just less frequently diagnosed in our clinics. So things like Kohn's disease, hyper aldosterinism, Cushing's disease, hyperadrenal corticism, etc.
Etc. And then from a renal perspective, the most common cause of polydipsia ass associated with renal disease would be chronic kidney disease, which we all see very, very routinely in our clinics, probably affects at least a third of our older cats. But acute kidney injury, pyelonephritis, E.
Coli infections in particular. Of the kidney can interfere with renal concentrating ability. So partly that's because of a nephrogenic diabetes incipidus impact of that infection.
So that would be other potential causes of polydipsia to compensate for that polyuria. I mentioned a routine blood tests in in the context of our polydipsy cat, so we would want to really focus on the biochemistry here. I always do the haematology as well, but it's, it's generally unlikely to, to give you the answer, whereas the biochemistry is is very much more likely to inform the answer.
So we're looking of course at renal function, urea creatinine, S. If you have that available as well. From an electrolyte perspective, hypercalcemia, hyponatremia and hypokalemia are the electrolyte disturbances that can be associated with polydipsia in cats.
Obviously glucose, potentially fructosamine, . It's a measure of diabetes and T4, your thyroxine test for hyperthyroidism would be examples of this sort of starting blood test. So typically I'll do a broad haematology biochemistry profile that includes electrolytes, and in any older cat, always add in a T4.
So back to Percy and then we'll, we'll do some other cases. So Percy, drinking 200 to 400 mL per day. So, urinalysis, as I've mentioned, is, is certainly the most important of our, initial samples to get from a polydipsy cat.
And so we got a urine sample from Percy and results are shown on the right hand side. Key findings really here are that the specific gravity is high, so greater than 1050. So he's got very concentrated urine in spite of this large thirst.
He has got a little bit of proteinuria. His UPC is a bit elevated, 0.51, above 0.4, considered abnormal currently.
Other than that, relatively unexciting urinalysis. So why is Percy polydipsy? Well, firstly, he's not polyuric, so that that's has very much come through from that urinalysis because he had that concentrated urine specific gravity.
And that concentrated urine is consistent with a compensatory polydipsia. So he's drinking more because of fluid loss somewhere. The fluid loss is not through the kidneys, but is it through his skin.
He has this generalised skin disease. Excuse me. So some exudation and over grooming affecting his skin.
But also you will remember, he had diarrhoea as well, and that is obviously going to contribute to fluid loss as well. So, in terms of his polydipsia, obviously just one of the presenting signs. I'm not going into any of the, the skin and GI workup that Percy had, and I will just say it, it was resolvable.
He went on to do very well. And his polydipsia resolved once his skin disease and diarrhoea also were effectively treated. So he's a slightly unusual polydipsic cat in that it was a huge polydipsia, but not associated with polyuria.
Let's do another couple of cases before we finish and have a bit of discussion with these. So this is Bonnie, a 12 year old female neutered domestic short hair. Everything was all fine until January when she was brought in with a history from her owners of recent polydipsia.
As with Percy, quite marked, so drinking up to 0.5 litre per day. Her appetite seemed quite normal, always she's been reported to have a good appetite, and, .
Owners had not noticed any other changes. In fact, she'd not lost weight according to our records either, and on physical examination, not a lot that really specifically informed us. Her blood pressure was a little bit high, whether that was related to anxiety or whether it was genuine, it was not clear.
At this, first instance, she didn't have any, obvious ocular target organ damage, so we certainly weren't, going to start her on, management for hypertension at this point. We wanted to repeat that reading. She had a little bit of dental disease, no palpable goitre, think of hyperthyroidism as a possibility.
Also that polydipsia is more extreme than would be typical for a cat with hyperthyroidism. She also had not lost any weight, which would be typical with a hyperthyroid cat as well. She did have a heart murmur, but that actually was something that had been reported some time ago, never investigated.
So, on examination, . Bonny's bladder was too small to obtain a cysto sample, so I gave her owners a cat coki and asked them to collect a sample from her at home a few days later, which they did, and they brought in me, and the urine actually had, you know, pretty concentrated specific gravity, 10:43, but a lot of glucose in it, other than that, a normal, so no ketones, bilirubin, blood or or protein. Just a lot of glucose.
So before we talk about the glycosuria, diagnostically for Bonnie, I just wanted to have a little detour into the impact of glucosuria on urine specific gravity because certainly I remember very much being taught at that school that presence of glucose in the urine sample will artfactually increase that specific gravity. But, some studies have been done, quite recently looking at this in much more detail. So this is a sample of, cats and dogs, just over 100 dogs and 59 cats, and looking at the impact of glucose on urine specific gravity.
So they actually, added, glucose to urine samples. And what they found was that actually, you do, adding glucose does alter the specific gravity, but not as much as we might imagine. So we can still look at the urine specific gravity in in the normal way that we would do in terms of assessing concentrating ability.
So the impact is relatively small. So back to to Bonnie and that sample. So is Bonnie diabetic?
Well, certainly the presence of glucose in that urine sample is very suspicious for diabetes and it's a home collected sample, so she's not stressed. Stress, as we all know, can increase blood glucose and. It actually can increase blood glucose above that renal threshold.
So it is possible to get a stress, glycosuria, but in Bonny, this sample was collected after she'd been at home for a few days, so I, I think, you know, that that was not a consideration. If we had had ketones in that urine sample as well, that would have absolutely nailed the diagnosis because presence of glucose and ketones combined. Is diagnostic for diabetes, but nonetheless suspicious, but also definitely something we wanted to look at a little bit more now and of course we want to do some further tests and I wanted to recheck the blood pressure as well because as you remember, that was a little bit high.
So I recommend they brought Bonnie back. We rechecked her blood pressure and that was fine. We collected some blood and the the glucose was elevated, and you can see just over 20.
I also did run a fructosamine, which was elevated to like. Confirms that this is a long standing, as in at least a couple of weeks, likely longer than that, that Bonnie has been hypoglycemic because that fructosamine, which is glucose combined with albumin is also very elevated. And, she also was very lipemic.
Her blood looks like paint, having been spun down. She had a mild, mild to moderately elevated liver enzymes, so very much typical picture of, of a cat with diabetes, and she went on to do very well with, pro zinc insulins. This was actually last year, so last January pre Sen Valgo, as a treatment option.
So a diabetic polydipsic cat, to, to start the the that or to finish that case discussion. And then lastly, we've got Ebony here. This is Ebony, 16 year old, female neutered domestic short hair, presented with a history that included weight loss, a good appetite, but also they had seen that she was drinking more often.
So, we've not got a. As detailed information as we had for Barney or Percy, so don't have a quantity of water being consumed. The implication really from the vibes I got from the owner was, was that perhaps it was less severe polydipsia, but nonetheless, they'd seen a significant difference in her.
And of course all the sort of routine differential diagnoses on our list here. So you know, things like kidney disease, diabetes, hyperthyroidism, physical examination didn't really add further information for us. I, I couldn't feel a goitre in her, in, in the consulting room, and there wasn't, .
She wasn't noticeably tachycardic, or, had a heart murmur, which are things I often look out for in our, in the context of hyperthyroidism. She did have some mobility issues. Unfortunately, she had urinated on her way to the clinic, so we didn't have a bladder that we could assist her at this point again just focusing on that polydipsia workup.
But clearly we wanted to do more investigations because. This is a cat that has lost weight over a period of time. And as a snapshot, this is her, her biochemistry test results that we got on that occasion shown here.
So the abnormals are shown in bold and italics here, so you can see that on her routine biochem panel, her proteins are fine, her renal parameters, also look fine, but her glucose is elevated just above the renal threshold, so it's 15.6 millimo per litre. Her liver enzymes both also moderately elevated both alkaline, phosphatase and, and, alanine amino transferase are both, moderately elevated.
So what's going on with her? This is the sort of biochemistry that we might see in a diabetic cat, but also it's the sort of biochemistry we might see in a cat with liver disease that is stressed or perhaps a hyperthyroid cat as well. There are a few possibilities going on, and certainly in the absence of, of that, that home collected urine sample, we could certainly can't rule out that, the possibility of, a stress hyperglycemia in Ebony.
Very definitely don't want to just go straight, straight onto insulin management for her. Stress hyperglycemia is, reasonably common, depending on, on your clinic and also your handling and your patients. Certainly there is a higher likelihood of stress hyperglycemia in cats that, that struggle and vocalise.
And so. Minimal restraint, very much recommended. If you have cats that do get distressed, then consider rescheduling, consider some pre-visit gabapentin, for example.
There may, I think, still soon be a licenced pregabalin as well for anxiety associated with vet visits. Never, never fight with your patients, because amongst, other things, obviously we don't want to stress out our patients anyway, but it will increase the risk of stress hyperglycemia, which can be quite huge, as you can see on this slides. So one study, the median glucose and and stress cats was, 10.8, but it actually went up to 60 in, in, you know, one cat in that study.
So a lot of overlap with the diabetic cats very much can exceed the renal threshold and result in in glycosuria. So tactics we have, if we think we might be dealing with stress, hyperglycemia would include, of course, if we have a simultaneous urine sample that has no glucose in it, then it probably indicates that that elevated blood glucose is is stress, if we have a a blood glucose that's well above the renal threshold. We do have the option of repeating blood glucose, but we also have the same risk of repeat stress.
That home urine sample can definitely be helpful, but if we've got enough of our blood sample there and then at the time, we can obviously run that for a fructose. That's the glycosylated serum protein, albumin complex to glucose. And that as you saw with Bonnie was instantly helpful in terms of just double checking, double confirming, our, diabetes.
In fact, in ebony, she was a cat with hyperthyroidism. She didn't have a palpable goitre because she had an ectopic thyroid, which is shown in the sintigraphy picture on the right hand side. This very, very hot spot here, is actually, a hyperfunctional thyroid within the anterior thorax, so the heart, you can just about see, here, this is like a sort of a dorsoventral image of her, salivary tissue up in the head that also shows up with this integraphy.
And the neck area where of course our thyroid normally is, there's no hyperfunctional tissue there, so no goitre that could be felt. The hyperfunctional tissue was all within the chest. So she was a, a stress hyperglycemia, hyperthyroid cat.
As an aside, hyperthyroid cats do metabolise their proteins more quickly, so tend to have lower fructosamine. So your, your combined hyperthyroid diabetic cat, that is one of the challenges, just to be aware of is that fructosamine levels will be lower in an uncontrolled hyperthyroid cat because of the, the faster metabolic rate. But in ebony, she was not diabetic, er, her, her glucose was was a stress high and she was just a, a hyperthyroid cat that went on to have successful treatment with radioiodine.
So in conclusion, polydipsia definitely is a common presenting sign. I think drinking more than they used to is a good enough definition of polydipsia. You don't need to get people to measure water intake, but certainly the magnitude of the thirst can be helpful in guiding our list of differentials.
Diagnostically, the urinalysis is absolutely essential part of investigations. If you have the cat there and then with you and you can palpate the bladder, then generally it's, you know, easiest, quickest to get that cystocentesis sample straight away, but the home collected sample is absolutely fine for the majority of cases and the majority of analysis. So, you know, don't hesitate to do that.
And then of course, hopefully you can get the diagnosis and start management of that cat, which ultimately will improve the cat's clinical status, hopefully the polydipsia as well, in the case of the diabetic cat, obviously in the kidney cat, they're going to remain polydipsic for the rest of their life. I referenced some resources on my website, so this is just a little reminder on how to get there. So it's vetprofessionals.com, helpful info, the free downloads are sort of technical guides, some sort of, PDFs of PowerPoints in there as well.
Video tutorials has got some free to access webinars for vets, but also some free to access ones for. Which were recorded as a cat cafe during COVID, so a variety of topics in there, including things like diabetes, and, I hope you'll find that information helpful. Thank you again very much for choosing to watch this webinar.
I really hope that you've found it helpful for your case management. Thank you.