March 5, 1999

By Richard Karel

As those conversant with the life of Sigmund Freud know, the founder of psychoanalysis was rarely far from his little dog Jofi while listening to his patients on the couch.

Given his love of dogs, Freud would probably approve of the evolving adaptation of human psychiatric drugs to help dogs deal with their own inner demons. Although some veterinarians have been using psychiatric drugs such as Prozac (fluoxetine) off-label to treat canine psychological maladies, until this January the Food and Drug Administration (FDA) had not approved behavioral drugs specifically for dogs.

The FDA approved use of clomipramine for canine separation anxiety and use of selegiline for symptoms of canine cognitive dysfunction syndrome (CDS) in January, according to information released by the FDA. Clomipramine will be marketed by Novartis Animal Health U.S. Inc. under the brand name Clomicalm. Selegiline will be marketed by Pfizer Inc. under the brand name Anipryl.

About 60 percent of dogs over age 10-up to 6.5 million canines-may be afflicted by at least one symptom of CDS, according to Pfizer spokesperson Robert Fauteux. Separation anxiety affects as many as seven million dogs in the U.S., according to Hans-Beat Gurtler, director of Novartis Animal Health in Basel, Switzerland, the company's home base. Clomicalm was approved in Europe last April.

Irwin Rothman, M.D., D.V.M., a private-practice veterinarian-turned-psychiatrist, spoke with Psychiatric News about the developments.

"It's unfortunate that a very large number of dogs are euthanized in this country because the owners are disturbed about their animal's behavior," said Rothman. "Some dogs with separation anxiety tear the house apart or bark continuously."

Clomicalm, in combination with behavioral therapy, "has the potential to save these dogs." As is the case in human psychiatry, it is best not to rely entirely on the medication, but rather to combine it with "some form of behavior modification," said Rothman.

CDS can be particularly heartbreaking as owners watch a beloved elderly dog lose recognition of familiar faces and forget his housebreaking training, said Rothman. The advent of selegiline provides another option to euthanasia, he observed.

Selegiline is approved for human use as a treatment for Parkinson's disease, but is used off-label by psychiatrists and neurologists to enhance cognition, according to Rothman. It is not surprising that it is proving helpful in improving canine cognition, he noted.

Up to now veterinary psychiatry has relied on empirical knowledge to adapt human psychiatric medications for off-label use in domestic animals, Rothman observed. Fluoxetine, for example, has been used off-label in dogs for a variety of conditions, including the canine equivalent of obsessive-compulsive disorder called canine acral lick dermatitis, in which a dog continuously licks its paws until they become raw. In some cases the licking becomes so severe that it is disabling.

At its simplest, off-label use of drugs such as fluoxetine by veterinarians for pets requires calibrating dosage to an animal's weight. But off-label use of other drugs may be considerably more complicated, since some medications well tolerated by humans may be highly toxic to dogs or other animals.

In addition to fluoxetine, other selective serotonin reuptake inhibitors, benzodiazepine tranquilizers, and barbiturates are used off-label for pets. Sedatives have been used for sedation, particularly for pets confined for travel, and barbiturates have long been used to control epileptic seizures, Rothman said.

The FDA approval of clomipramine and selegiline specifically for dogs "may be a new trend, because there is a very large market," said Rothman. A stroll down the supermarket aisles reveals a burgeoning array of pet-related products, he noted.

Whether the development or adaptation of psychiatric drugs for pets is a trend remains to be seen. But the consolidation of pharmaceutical companies may inadvertently push the industry that way. Although Pfizer Inc. has been involved in the marketing of medications for livestock since the 1950s, according to spokesperson Fauteux, it was the company's January 1995 acquisition of SmithKline Beecham Animal Health, which had a strong focus on pet medicine, that spurred Pfizer's adaptation of selegiline for CDS.

"When we evaluated the situation after the acquisition and recognized we had a significant stake in the companion animal area, we found there was a significant need for pet medications, particularly for older dogs," Fauteux said. Other medications for elderly dogs, such as Rimadyl, for pain associated with osteoarthritis, had been well received, he noted. Pfizer was also aware that veterinarians were using human drugs off-label. Further, Pfizer's annual research and development expenditures exceed more than $2 billion. "You can leverage this kind of investment across species," he noted.

People "don't want to see their pets suffer," he added. Pfizer has not yet launched a promotional campaign for Anipryl but has received many media calls, said Fauteux. "Because we hadn't sent out a press release, we were surprised and pleased at the intensity of the interest."