Hi Angela and welcome
I am sorry your Harry has Addison's. When an Addisonian dog is being well controlled he should look and behave as a normal dog, only having to give more pred at times of stress. So the hair loss and any other symptoms that contribute to Harry looking old is likely to be due to poor control of his Addison's eg., perhaps the dose of Zycortal is too high.
Do you have Harry's blood results? I am surprised he is still on 2.25mg/kg of Zycortal. I presume this is given every month. This was the initial starting dose as per the drug sheet when Zycortal was introduced two years ago but since then it has been generally accepted that this dose is too high and the current thinking is a better starting dose of 1.5mg/kg is the norm now, and then adjusted as necessary.
All the dogs I have known to have started on 2.2mg/kg have had the dose gradually reduced because the sodium and potassium ratio after one month is too high. Usually if this is higher than ideal (>34) then the next dose may be delayed for a week until another blood test indicates that the next dose is needed or the dose is reduced. I have known dogs to go up to 90 days without further injection of Zycortal because the dose was too high. There is a bearded collie who is now on 0.5mg/kg Zycortal each month and he started his treatment when it was first introduced two years ago.
The aim is to establish the correct replacement dose for the individual dog that lasts through one month, but this doesn't mean just giving a jab every month and assuming that the sodium and potassium levels and ratio is normal or not taking notice of high electrolyte levels and just giving the monthly jab regardless. If you ask for the test results you will be able to see if the dose is correct or not but Harry's clinical signs will tell you so much.
I believe Harry can be much better than he is, so if you have any queries, please get back to me.
Jo
Below is an extract from the Zycortal drug sheet:
Initial dose of ZYCORTAL Suspension:
The initial dose is 2.2 mg/kg (1 mg/lb) body weight, administered by subcutaneous injection.
Interim monitoring visit:
Re-evaluate the dog and measure the serum sodium/potassium ratio (Na+/K+ ratio) approximately 10 days after the first dose, which is the time to maximum concentration (Tmax) of desoxycorticosterone (see CLINICAL PHARMACOLOGY). If the dog's clinical signs have worsened or not resolved, adjust the dose of prednisone/prednisolone and/or investigate other causes of the clinical signs.
Second dose of ZYCORTAL Suspension:
At approximately 25 days after the first dose, re-evaluate the dog and repeat the Na+/K+ ratio.
o If the dog is both clinically normal and has a normal Na+/K+ ratio on Day 25, adjust the dose based on the Day 10 Na+/K+ ratio using the guidelines in Table 1, below.
o If the dog is clinically normal and has a Na+/K+ ratio > 32 on Day 25, either adjust the dose based on the Day 10 Na+/K+ ratio according to Table 1 or delay the dose (see Prolonging the dosing interval).
o If the dog is either not clinically normal or if the Na+/K+ ratio is abnormal on Day 25, adjust the dose of prednisone/prednisolone or ZYCORTAL Suspension (see Subsequent doses and long-term management).
Table 1: Day 25: Administering the Second Dose of ZYCORTAL Suspension
If the Day 10 Na+/K+ ratio is: Do not administer Dose 2 on Day 10. 25 days after the first dose, administer ZYCORTAL Suspension, as follows:
> 34 Decrease dose to: 2.0 mg/kg
> 32 to 34 Decrease dose to: 2.1 mg/kg
27 to 32 Continue 2.2 mg/kg
24 to < 27 Increase dose to: 2.3 mg/kg
< 24 Increase dose to: 2.4 mg/kg
Prolonging the dosing interval:
If the dog is clinically normal and the Day 25 Na+/K+ ratio is > 32, it is possible to prolong the dosing interval instead of adjusting the dose as described in Table 1. Evaluate the electrolytes every 3-7 days until the Na+/K+ ratio is < 32, and then administer 2.2 mg/kg of ZYCORTAL Suspension.
Subsequent doses and long-term management:
For subsequent doses, use the following guidelines if the dog is not clinically normal and/or has abnormal Na+ or K+ concentrations:
o Clinical signs of polyuria/polydipsia: Decrease the prednisone/prednisolone dose first. If the polyuria/polydipsia persists, then decrease the dose of ZYCORTAL Suspension without changing the dosing interval.
o Clinical signs of depression, lethargy, vomiting, diarrhea or weakness: Increase prednisone/prednisolone dose.
o Hyperkalemia, hyponatremia or Na+/K+ ratio < 27: Decrease the ZYCORTAL Suspension dosing interval by 2-3 days.
o Hypokalemia or hypernatremia: Decrease the ZYCORTAL Suspension dose.
Prior to a stressful situation, consider temporarily increasing the dose of prednisone/prednisolone.