Phenobarbital is a very safe and effective drug that has been used for many years in cats. It is used for seizures and for a variety of behavior problems. At the Animal Clinic at Thorndale we have a lot of experience with this medication in both cats and dogs. If you have any questions about your cats response to this or any other medication please call us.
Phenobarbital is a depressant of the central nervous system (brain and spinal cord). If it is overdosed or if your cat is especially sensitive to it, drowsiness, excessive sleep, and even staggering when walking will occur. On the other hand, if it is not dosed high enough, the desired effect will not be achieved. Sometimes an under dosed cat will actually appear agitated. Therefore, our goal is to find the correct dose that controls the problem without causing drowsiness and staggering.
Some cats are more sensitive to this drug than others; therefore, the initial dose is always subject to change. If no response occurs, the dose will be increase. If excessive drowsiness or staggering occurs, the dose will be decreased. However, please note that this drug should be given twice daily for best results. Since the tablets are so small, it is tempting to lower the initial dose (usually one 1/4 grain tablet twice daily) to one tablet once daily. However, to get best results the lower dose should be 1/2 tablet twice daily.
Phenobarbital is metabolized (broken down) by the liver so that it can be eliminated from the body. However, cats do not have a very efficient system for doing this when they first begin taking the drug. After the cat has been taking it for about 7-10 days, the liver creates new enzymes that make this elimination process more efficient. This means that the cat will effectively lower its own dose after 7-10 days because the drug will be broken down and eliminated more rapidly. This has some important implications in treatment:
- If your cat is initially slightly drowsy, sleeps slightly more than normal, but does not stagger when walking, continue that dose. After the initial 7-10 day period, these signs of overdosing will go away as the liver works more efficiently.
- If your cat has a very good response but is not drowsy during the first week of treatment, it is possible that the response will diminish when the liver becomes more efficient at metabolism. This means that you and your veterinarian may need to adjust the dose.
If you are uncomfortable concerning your cat’s response to phenobarbital, do not hesitate to call for assistance.