Replying to Mariska H. 07/09/2022 - 02:56
Hello.
Thank you so much for these brilliant questions. I have posted your questions below and then popped my thoughts underneath:
1. Is there a benefit of performing in-house sediment exams to look for bacteria/neutrophils (if very easy to miss wbc etc)? Would you just do it to look for crystals? I perform it with every urinalysis but always wonder if I am doing it correctly/wasting my time and should just send it off for cytology. Do you do it with every urinalysis?
This is a great question. I suppose it comes down to why you are doing the urine analysis. In some cases the most important information is the USG and the rest is less helpful. I think in any case where you suspect UTI or crystals/stones it would be important. However, struvite, amorphous phosphate and oxalate crystals are commonly seen in urine of healthy animals. Urate, cysteine, or large quantities of calcium oxalate crystals are usually abnormal. If you get any other abnormalities on your initial dipstick, I would also do sediment exam. If you get blood or protein on dipstick I would also do a sediment exam.
2. What is your technique to get a good diagnostic sediment slide?
This is a really good guide for sediment preparation:
https://www.bristol.ac.uk/media-library/sites/vetscience/documents/clinical-skills/Urine%20Sediment%20Preparation.pdf
3. With incontinent dogs – when would you consider looking for a UTI? I recently had a dog on stiboesterol for 5 years from another vet, owner said had been licking vulva for 5 (?!) years. I treated for UTI and she came off the pills. I felt so bad for the poor dog. So now when I am newly diagnosing an incontinent dog I always worry that they have a UTI primarily or as well as being incontinent.
Good question. I think it depends a bit on the reason for the incontinence. In most cases I would look when there are signs of a UTI. I tend to not look for infection unless they are showing signs of stranguria, dysuria or pollakiuria. Some of these clinical signs will cross over between UTI and incontinence. It would not be unreasonable to culture the urine of dogs in the initial phases of an incontinence work up.
4. Molly has Na:k ratio 27. What makes you not test for addissons? Simply because no clinical signs?
Indeed. I think we have to be careful with the Na:K ratio. It can be low for other reasons. I would only worry about Addison’s if there were other compatible signs.
5. Could you briefly go through the changes you would expect to see on bloods etc and pathway to diagnose pyelonephritis (temp?) and AKI (not anuric) please? I feel like these are the two I struggle with in practice.
Urinalysis not only is instrumental in the diagnosis of pyelonephritis, but it will also provide valuable information on possible comorbidities. In turn, this determines the need for additional diagnostic tests and is an important element for guiding the treatment plan. Sampling method, sample volume, and macroscopic evaluation should be noted, and will help with interpretation of final result. A routine urine examination generally includes refractometer determination of specific gravity and dipstick analysis for presence of at least glucose (combined with ketones) in view of predisposing factors.
Microscopic examination will help distinguish haematuria from haemo- (myo-) globinuria and could hold clues to help with localization (casts, different epithelial cells) and underlying disease (e.g., crystals, infection). Examination of stained, air-dried sediment can allow identification of white blood cells and potential causal agents (ranging from bacteria, yeasts, and fungal components to parasite ova). The magnitude of presumed renal proteinuria, which is measured by means of a urinary protein-to-creatinine ratio, is best assessed after urinary tract inflammation is addressed.
Assessing the haematocrit has no diagnostic value for pyelonephritis itself, but it can have an impact on patient management in view of suspected comorbidities, or when findings during physical examination were suggestive of either anaemia or erythrocytosis. Similarly, patients with pyelonephritis can display abnormal white blood cell counts ranging from leukopenia to (predominantly neutrophilic) leukocytosis. If characterized by a left shift, leukocytosis also can be indicative of secondary bacteraemia.
Whether cause or consequence, abnormal renal function is a common feature of pyelonephritis reflected not only in urinary abnormalities but also through serum electrolyte disturbances and possible development of azotaemia if both kidneys are involved. For those patients that show other comorbidities, a much wider range of parameters can become of interest; for example, in cases with glucosuria, plasma glucose levels will also be of interest.
I hope that helps!
Scott 🙂
