Unfortunately, as dogs get older, they can experience changes to their health and mental faculties. Some senior dogs show signs of cognitive impairment akin to human Alzheimer’s disease. This condition, known as cognitive dysfunction syndrome in dogs, causes issues such as disorientation, restlessness or lethargy, pooping or peeing in the house, and changes in sleep patterns.
Senior dogs can also develop tumors in their pituitary glands, or occasionally their adrenal glands, which leads to excess production of the hormone cortisol. This condition is known as Cushing’s disease, and early signs include excessive thirst and frequent urination. As the illness progresses, you may see weakness, loss of muscle mass, skin lesions, hair loss, obesity, and a lack of energy.
If your dog is exhibiting signs of any of these health conditions, discuss them with your veterinarian. After considering all diagnostic result options, your veterinarian might prescribe a drug called selegiline, also known by the brand name Anipryl. Read on to learn about the correct use of selegiline, how it helps, potential side effects, and alternatives.
What Is Selegiline Used for in Dogs?
According to veterinary psychiatrist and certified veterinary behaviorist Dr. Sagi Denenberg, DVM, Diplomate of the American College of Veterinary Behavior, selegiline is only used in North America for dogs with Cushing’s disease or cognitive decline. It’s licensed for use in Europe for chronic emotional disorders. However, monoamine oxidase inhibitors (MAO inhibitor), the class of drug selegiline belongs to, fell out of favor for emotional disorders when newer, more effective medications entered the market.
How Selegiline Works in a Dog’s Brain
Like a human’s brain, a dog’s brain uses neurotransmitters to communicate between nerves. One of these neurotransmitters is called dopamine, and it’s essential for memory function among other things. To prevent neurotransmitters from accumulating, the brain also has enzymes that break them down. One of these enzymes is monoamine oxidase, which gets rid of dopamine.
Selegiline works by inhibiting monoamine oxidase, allowing dopamine to stay in the brain longer. In the case of Cushing’s disease, dopamine regulates and inhibits the production of a stimulatory hormone called adrenocorticotrophic hormone (ACTH). ACTH can lead to the adrenal glands overproducing cortisol, which causes the symptoms of Cushing’s disease. Therefore, selegiline minimizes the effects of ACTH by helping keep dopamine around.
Cognitive impairment is associated with a drop in dopamine. So, by using selegiline and allowing dopamine to linger in the brain, there may be an improvement in cognitive dysfunction symptoms. In addition, Dr. Denenberg explains, “Selegiline enhances the activity of other enzymes, such as superoxide dismutase and superoxide catalase. These enzymes inhibit and degrade the brain’s toxic oxygen molecules (toxic free radicals). These toxic molecules cause oxidative damage inside neurons (burning the cell in lay terms), leading to brain tissue loss.”
Benefits of Selegiline
For dogs with Cushing’s disease, selegiline is only of benefit if the dog’s tumor is in the section of the pituitary gland where ACTH is dependent on dopamine. If the tumor is in another part of the pituitary gland, the medication will do nothing more than provide a general stimulatory effect.
In the case of cognitive dysfunction syndrome in dogs, Dr. Denenberg says studies have shown that selegiline helps improve memory and learning, both in the lab and in clinical settings. Dogs were tested in a variety of ways including remembering the location of food, learning to identify markers of food, and remembering where food was hidden. The dogs that were given selegiline performed better than those dogs that were given a placebo. However, he warns, “It is important to remember that the level of ‘success’ of using this medication is limited. It will not cure cognitive decline; it will only slow it and may cause some improvement.”
How to Administer Selegiline
Selegiline is given to your dog as a daily tablet. Since it’s a stimulant, so Dr. Denenberg advises administering selegiline in the morning. If you give it to your dog in the evening, your dog might be awake and alert through the night. He also says patience is a must with this medication, as it can take about four to six weeks to see if it’ll be helpful for your dog.
Your veterinarian will probably start at a low dose and increase it if needed. Missing one dose isn’t likely to cause any drop in effect as the level of dopamine will remain constant in your dog’s brain. However, a missed dose can impact your dog’s alertness and lead to restlessness and irritability.
Side Effects and Alternative Medications
When first starting your dog on selegiline, you may notice irritability and restlessness. The drug can also cause an upset stomach, and, in rare cases, reduced hearing. It’s also important you don’t feed your dog any hard cheeses or cured meats while they’re on selegiline, as the medication also affects the monoamine oxidase enzyme in the gastrointestinal tract. Dr. Denenberg says the likelihood of a reaction is low, since most dogs don’t get a lot of these foods. But the reaction can be fatal in humans on MOA inhibitors, so it’s best to practice caution.
In addition, selegiline shouldn’t be used with other drugs that impact serotonin, another brain neurotransmitter, such as SSRI’s or tricyclic antidepressants including Elavil and Prozac. Otherwise, your dog could potentially suffer serotonin syndrome, which is caused by excess serotonin in the body, leading to symptoms such as diarrhea, vomiting, decreased appetite, elevated heart rate, panting, pacing, and seizures.
If selegiline isn’t effective for your dog, there are other medications that increase dopamine, such as cabergoline and bromocriptine. But Dr. Denenberg says while they can be used, they’re neither licensed for this purpose nor as effective. For Cushing’s disease in particular, there are better alternatives to selegiline, such as the medications mitotane (brand name Lysodren) and trilostane (brand name Vetoryl). These drugs selectively destroy part of the outer section of the adrenal gland, so even though the pituitary gland tumor continues to release ACTH, the cortisol levels will remain normal.
For dogs with cognitive dysfunction syndrome, natural supplements can be helpful. Dr. Denenberg says SAMe, ginkgo biloba, apoaequorin, and resveratrol can all support brain function and reduce the levels of toxic free radicals in the brain. However, their efficacy hasn’t been proven to the same degree as prescription medications. In addition, prescription diets such as Hill’s Prescription Diet b/d and Purina Neurocare are licensed for cognitive decline in dogs and can help manage the condition.
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