Pets are commonly given a variety of medications to help treat a wide range of diseases and conditions. While most of these medications do not require regular drug monitoring, there are a few that do. Drug monitoring is the process of regularly testing your pet's blood to make sure the concentration of the medication is safe and within therapeutic levels. This is important because if the medication levels are too high or low, it can cause serious health problems for your pet. The most common diseases that require regular drug monitoring include epilepsy (seizure disorders), hypothyroidism/hyperthyroidism, Cushing's disease, and diabetes. Conditions treated with corticosteroids or NSAIDs also need to be monitored. By keeping track of your pet's drug levels, you can ensure that your pet stays healthy and gets the most out of his/her medication. In this article, we will discuss 6 common medications that require regular drug monitoring in both dogs and cats.
1) Phenobarbital for seizure disorders such as epilepsy
Common Drug: Phenobarbital is a common anticonvulsant medication, meaning it is taken to prevent seizures.
Monitoring: The therapeutic drug level for phenobarbital varies depending on the species it has been prescribed for. Your veterinarian will evaluate your pet's drug levels with the therapeutic levels to gain insight as to efficacy and safety. Levels are checked at least once a year and it is also important to check the drug levels any time there is a change in dosage. Your veterinarian will also recommend checking your pet's liver values as phenobarbital can have an impact on the liver.
2) Levothyroxine for hypothyroidism in dogs
Common Drug: Levothyroxine is a common medication taken by pets to treat hypothyroidism (low thyroid hormone levels).
Monitoring: Your veterinarian will recommend checking your dog's thyroid levels (T4) while on levothyroxine. Levels are checked at least once a year and it is also important to check the drug levels any time there is a change in dosage. It is very important that the blood collected for this test is performed 4-6 hours after the dose has been administered.
3) Methimazole for hyperthyroidism in cats
Common Drug: Methimazole is a common medication taken by cats to treat hyperthyroidism (overactive thyroid).
Monitoring: Your veterinarian will recommend checking your cat's T4 levels while on methimazole. Levels are checked at least once a year and it is also important to check the drug levels any time there is a change in dosage.
4) Trilostane for Cushing's disease (hyperadrenocorticism) in dogs
Common Drug: Trilostane is a common medication taken by pets to treat Cushing's disease, which is the result of an overactive adrenal gland.
Monitoring: Veterinarians do not typically check the blood levels for trilostane but will recommend checking the cortisol levels via the ACTH stimulation test. The test should be performed once a year and it is also important to check the drug levels any time there is a change in dosage.
5) Insulin and blood glucose levels for diabetes in dogs and cats
Common Drug: Insulin is a common medication taken by pets to treat diabetes, which is the result of an insufficient amount of insulin in the body or improper use/absorption of insulin.
Monitoring: Your veterinarian will recommend checking your pet's blood sugar levels 2 weeks after starting insulin and anytime when insulin dosing has changed. The best way to interpret the effects of insulin is to perform a glucose curve. This test involves sequential blood samples taken every 4 hours throughout the day to measure the effects of insulin on blood glucose levels.
6) Corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs)
Common Drugs: Corticosteroids include prednisone and dexamethasone; NSAIDs include Metacam™, Deramaxx™, Rimadyl™, etc. These medications are used to trial a variety of disorders such as seasonal allergies to arthritis.
Monitoring: Most of these drugs are monitored by checking the blood levels after 6-8 weeks of initial therapy. Thereafter, levels should be checked yearly to make sure that they are still safe to be used on your pet. Specifically, your veterinarian will want to evaluate your pet's kidney and liver values. Dose adjustments may be made depending on the results of the blood test.
Pets require regular drug monitoring to ensure that they are safe and healthy. The common medications that pets take, such as phenobarbital for seizure disorders or levothyroxine for hypothyroidism in dogs, all have different therapeutic ranges depending on the species prescribed them. These drugs should be monitored at least once a year with blood tests and levels checked any time there is an adjustment in dose or dosage. It’s important to keep these things in mind when giving your pet medications!