Hyperadrenocorticism (Cushing's disease, HAC)

Part 3 - Lysodren induction

Lysodren is a drug that selectively kills cells in the adrenal glands so that they cannot produce cortisol (cortisone). The goal in treatment is to eliminate the clinical signs of hyperadrenocorticism (Cushing's disease) while avoiding side effects from the drug. The initial dosing regimen is designed to suppress cortisol production quickly, so Lysodren is given daily. It will take anywhere from 3 to 10 days of daily therapy to adequately suppress cortisol production. Every dog is different. After the initial period your pet will probably need the drug only once or twice a week.

Induction can be tricky. We want to stop giving the medication as soon as the clinic signs of excessive thirst, urinating and appetite have subsided, then test the cortisol levels to make sure we are on target. If we give the drug for too long a period we run the risk of completely stopping cortisol production. This is not the goal! Some cortisol production is vital to your dog's health. Cortisol is a stress hormone, and a lack of cortisol can cause illness as well. We want to suppress the cortisol production so that there are normal levels in the body, not too little or too much.

It is very important that you monitor your pet's food and water consumption during treatment. Appetite may be one of the best indicators of the endpoint of induction. Measuring water consumption is also a good way to determine when we have reached our goal.

Determination of Lysodren induction endpoint:

1. Give a meal and watch your dog eat BEFORE giving each dose of medication. Watch HOW your dog eats the meal. We are looking for a subtle change in appetite. Most dogs with hyperadrenocorticism are voracious eaters, hardly pausing for breath during a meal. When we reach the endpoint of induction you will see small changes perhaps not eating as fast, lifting his head to look around occasionally, taking a bit longer to eat. The appetite is still good, but the dog will not have the same degree of urgency in the eating. If your dog is not eating exuberantly, we will need to decrease the amount fed by about 25% (just during the induction phase) so that he is hungrier. This will make it easier for you to see the subtle changes in his eating patterns.

2. Measure your dog's water consumption (in cups per day) every day. Allow his to drink as much water as he wants, but make sure you know how much water is in the bowl. Keep a daily log of how much water was consumed. At the endpoint there is usually a drop in the volume.

3. If at any time you think that you see these changes, do NOT give the next pill. Bring your dog in for an ACTH stimulation test as soon as possible (the same day or the next morning).

4. We should be in contact every day from day 3 onward to see how things are going.

5. You will be given a supply of prednisone tablets to have on hand at home should treatment become necessary.

6. If we get to 10 days on Lysodren and you have net seen the endpoint, bring your dog in for an ACTH stimulation test.

7. If your dog goes off food entirely, become lethargic or weak, has vomiting or diarrhea, we need to do an ACTH stimulation test immediately. These are signs of inadequate cortisol levels, and we may need to treat your dog. If this happens at night, give the prescribed dose of prednisone. Your dog should recover significantly within one hour. If there is little change you will need to take him to the emergency clinic to have his electrolytes checked. If your dog looks better after being given the prednisone, bring him to the clinic in the morning for an ACTH stimulation test. Please make note of the time that the prednisone was given; we have to wait 12 hours before the ACTH stimulation test can be done.

8. Most dogs induce within the first 10 days. Some will reach the endpoint in as little as 3 days. Once the endpoint has been reached, a maintenance dose of Lysodren will be started, to be given 2 or 3 times a week. We will then recheck the ACTH stimulation test a month later to confirm that the dose is correct.