scott@vtx-cpd.com

Hi there!

Great question about monitoring Cushing’s disease with pre-Vetoryl cortisol levels. There’s no perfect way to monitor the response to trilostane, and both the pre-pill (pre-Vetoryl) cortisol and ACTH stimulation tests have their roles. Here’s a breakdown based on current understanding:

Pre-Vetoryl (Pre-Pill) Cortisol:

Usefulness: Pre-pill cortisol can be useful in certain cases, but it has limitations. It’s not ideal if the dog is aggressive, very stressed, or unwell at the time of sampling. Additionally, the samples must be submitted to an external lab, as studies validating this method were not done using in-house machines.
Limitations: Cortisol secretion is episodic, so a single sample may not provide complete information. If you get a low result from a pre-pill cortisol test, it’s still advisable to run an ACTH stim test to ensure the adrenal reserve is not over-suppressed.
ACTH Stimulation Test:

Role: The ACTH stim test is the traditional method and is useful to ensure that the adrenal axis is not over-suppressed. It helps verify that the treatment is not too aggressive.
Limitations: Neither the ACTH stim test nor the pre-pill cortisol can tell you if you are giving enough trilostane. You need to consider the clinical response (i.e., resolution of clinical signs like polyuria and polydipsia).
Dosing Considerations:

Many cases do require twice-daily administration of trilostane. However, due to the cost, starting with once-daily dosing is reasonable, hoping it will be sufficient.
If ACTH stim or pre-pill cortisol levels are within the recommended range or higher and clinical signs persist, there may be scope to increase the trilostane dose.
Reference ranges for cortisol are different from therapeutic ranges; the lab should highlight these differences.
Adjust doses based on the persistence of clinical signs, not just test results. If tests suggest potential over-suppression but the dog is still showing clinical signs (like polyuria/polydipsia), consider splitting the dose to twice daily. Confirm this need with an ACTH stim at 22-24 hours post-pill if necessary.
Twice-Daily Trilostane:

Equal doses should be given morning and night to facilitate monitoring and avoid peaks and troughs in drug concentration.
Summary:

Clinical signs are the mainstay of monitoring trilostane response.
ACTH stim or pre-pill cortisol tests help avoid over-suppression of the adrenal axis.
Adjust trilostane dose primarily based on clinical signs, using these tests to guide safe dosing.
Additional Resources:
Lesley has also offered some useful resources that can provide further guidance and insights into the management of Cushing’s disease.

If you have any further questions or want to discuss this more, feel free to reach out!

Thanks,

Scott 🙂

Great Question!

Tayer also asked a similar question from lesson one which I will pop here:

“One question I have from the first lesson on Haemoabdomen – you mentioned stabilising the hypovolemia and hypotension but didn’t mention fresh frozen plasma. If you were able to maintain PCV and stop active bleeding but low TP would use it then or do you tend to just stick with colloids and wait for body to reproduce? If so when do you reach for the plasma and why…”

Scott 🙂

Replying to Katherine Howie 26/05/2024 - 21:00

Hi Kath,

Thanks for elaborating on this. It’s a great reminder that even without all the advanced monitors, we can still gather crucial information through thorough physical exams and assessing perfusion parameters. Your point about hypotension only appearing after a significant drop in cardiac output is really important—it’s good to remember that a patient can be hypoperfused even with normal blood pressure.

I completely agree that hands-on assessments and repeated serial physical exams are invaluable. It’s reassuring to know that these fundamental skills can provide us with so much insight into a patient’s cardiovascular status.

Thanks again for sharing your expertise!

Best regards,

Scott

Replying to Raquel M. 25/05/2024 - 15:34

Hi there,

Thanks for your question! Urine dipstick strips that differentiate between RBCs, hemoglobin, and myoglobin based on the pattern of the color change can be quite useful in a clinical setting. These strips can provide a quick and easy way to get a preliminary assessment of hematuria versus hemoglobinuria or myoglobinuria.

However, there are a few points to keep in mind:

Accuracy: While dipstick tests can be helpful, they are not always 100% accurate. False positives and false negatives can occur, so it’s important to confirm any suspicious results with more definitive testing, such as microscopic examination of the urine sediment or additional blood tests.

Interference: Various substances in the urine, such as certain medications, foods, or contamination, can sometimes interfere with the results of the dipstick test.

Clinical Context: Always interpret dipstick results within the broader clinical context. For example, the presence of RBCs in the urine should be correlated with clinical signs and other diagnostic findings to determine the underlying cause.

Follow-Up: If the dipstick test indicates the presence of hemoglobin or myoglobin, further testing may be needed to determine the source. Conditions like hemolysis or muscle damage can cause these substances to appear in the urine, and additional diagnostics will be necessary to address the underlying issue.

In summary, urine dipstick strips can be a valuable tool for initial screening, but they should be used alongside other diagnostic methods to ensure accurate and comprehensive assessment.

Hope this helps, and feel free to ask if you have any more questions!

Best regards,

Scott 🙂