“Pred” is a term that the doctors and staff at the Animal Clinic at Thorndale often use for prednisone or prednisolone. These are cousin drugs that are classified as corticosteroids or “steroids.” They are almost interchangeable so we use them as if they were synonymous. The difference is that prednisolone is the active form of the drug. If that drug is taken, it is ready to go to work immediately. Prednisone must be converted to prednisolone (by the liver) to be in an active form. It is a little slower to act (by a few minutes to hours). However, its main disadvantage when your cat has liver disease. If the liver is not working well, prednisone may not be converted well and thus may not be very active.
Prednisone is a very powerful anti-inflammatory drug. It can be life saving to cats with a wide variety of diseases. Therefore, it is used often.
Most cat owners are quite concerned about side effects from prednisone. This concern is generally founded in the problems that people often have who take prednisone. However, the cat is extremely resistant to side effects from prednisone.
The most common side effects seen in cats are stimulation of thirst and appetite and an increase in urination. These are dose related. They may occur at high doses, but will generally not occur at low (maintenance) doses. If they do occur, they will stop when the drug is stopped or the dose is lowered.
Prednisone in cats can be used safely for many years if two precautions are taken:
1) Use the lowest dose possible. Prednisone is usually started at a fairly high dose. When response occurs the dose is then gradually reduced until the lowest dose is found that will control the disease.
In some cases, an injectable steroid is given to achieve control of the disease. Many of the long-acting injectable steroids give relief for 2-4 weeks. If this is done, prednisone should be started at the first sign of any recurrence of the disease being treated and used at a low, maintenance dose.
2) Give on an every-other-day schedule in the evening. The adrenal glands produce cortisol, a cousin to prednisolone and prednisone. This is an important corticosteroid that the body needs. In addition to cortisol, the adrenal glands produce other important products for the body. If prednisone is dosed so it is constantly in the body, a message will be sent to the adrenal glands telling them to quit working. After a few days to weeks, the body suffers from the loss of some of the adrenal glands’ products. However, every other day dosing can help prevent adrenal gland shutdown.
Prednisone is eliminated from the body in about 36 hours from the time it is given. If it is given every day, some of yesterday’s dose is present so it is never out of the system, and the adrenal glands stay suppressed. However, if it is given every 48 hours, or every other day, this problem is solved. It is preferable to give cats prednisone in the evening because it has less effect on the cat’s own internal cortisol rhythms.
Therefore, the safe use of prednisone in cats requires that the lowest effective dose be given on an every-other-day schedule.