Zycortal Symposium Proceedings

dose increments should be +/-25 to 50% of the previous dose. At times of metabolic stress or illness, the glucocorticoid dose may need to be increased (2- to 4-fold).

It may be possible to use endogenous ACTH to assess glucocorticoid supplementation but more work is required before this can be suggested for routine monitoring. 7

Mineralocorticoid supplementation

The authorised initial dose of DOCP is 2.2 mg/kg SC given approximately every 25 days 8 . Many authorities however use a starting dose of 1.5 mg/kg SC given every 28 days. It is very important to make sure that the product is properly resuspended before drawing up the injection (and the syringe should continue to be gently rotated after drawing up the dose before injection to avoid precipitation in the needle). Longer intervals (e.g. 35 days) increase the risk of instability (but may be cheaper for the client). There is no evidence that there is an extended duration of action but many dogs, if their dose is delayed, do not show electrolyte abnormalities for some time 9 . This is consistent with the long period between the onset of clinical signs and the development of electrolyte abnormalities seen before diagnosis in many cases. Most dogs require adjustments to their initial dose and it is more likely that dogs will require a dose reduction than a dose increase if using a starting dose of 2.2 mg/kg. The decision to change the dose is made by assessing electrolytes and clinical signs. The aim is to keep potassium and sodium within their reference intervals throughout the dosing interval. To assess this, it is necessary to check at 10 (+/-3) and 28 (+/-3) days post injection after every dose until stable. Monitoring electrolytes at 10 days post injection enables assessment of the peak effect of the dose whereas the 28 day sample enables assessment of the duration of the dose. If the peak effect is too great (or too little) at 10 days post injection then the subsequent dose should be reduced (or increased). If the potassium is below and/or sodium is above their respective reference range at 28 days then DOCP should not be administered and electrolytes should be checked every 7 days until they are within their respective reference ranges and then DOCP administered (at a reduced dose of about 20% less than the previous dose). If the dog still has electrolyte abnormalities consistent with hypoadrenocorticism at 28 days, then DOCP must be injected at a higher dose (or the interval shortened). A dog can be regarded as being on the correct dose of DOCP when it is clinically well and has electrolytes within their respective reference ranges on days 10 and 28 post injection for at least two consecutive treatment cycles using that same dose. Once the correct dose has been determined, dogs should be reassessed every 4-6 months at the time of (or just before) injection. It is possible to lower monthly DOCP doses in some dogs (in some cases to much lower levels than the starting dose 10 ). Such approach might be justified on cost grounds in some cases but this approach also requires more monitoring tests. It should also be noted that the study had a surprisingly high death rate (25%) though the authors suggest that the cause of death was never hypoadrenocorticism. It is important to be aware that there are day to day variations in sodium and potassium concentrations (Unpublished results). There are also differences between results from different laboratory analysers that cannot be explained by different reference ranges 11 . Therefore, very small or inconsistent changes may not be clinically significant. If in doubt it is entirely appropriate

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