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The generic version of Viagra—the drug men use to treat erectile dysfunction—could help dogs who suffer from a rare esophagus disorder, a new study finds.

When given to dogs with megaesophagus, liquid sildenafil allowed food in the esophagus to pass into the stomach, Washington State University researchers found. That's often a challenge for dogs who suffer from the disorder, which causes the esophagus to grow and lose its ability to usher food into the stomach.

The disorder can cause dangerous regurgitation and aspiration, so a preventative drug could improve dogs' lives massively.

"I think sildenafil will be life-changing and life-saving for a lot of dogs. This research helps support its use and hopefully will encourage more people to use it," Jillian Haines, DVM, MS, and a co-author of the study, said in a news release. Haines conducted her research alongside Susan Mehain DVM, MS, and Sarah Guess DVM, MS.

In the study from the WSU College of Veterinary Medicine, sildenafil reduced the amount of food dogs with megaesophagus regurgitated. Ten dogs entered the study, and nine of their owners reported fewer regurgitation episodes during the two weeks their dogs were on sildenafil. Regurgitation can cause food and liquid to enter the lungs, putting the dog's life at risk.

"If you look at the literature, there are no drugs we can use to manage megaesophagus. Sildenafil is the first to target these mechanisms and reduce regurgitation, which is big because that's what ultimately kills these dogs," Haines said.

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Dogs with megaesophagus often have to eat in a "Bailey chair," an upright seat that keeps the dog 45–90 degrees to the ground, according to VCA Animal Hospitals. The pups have to remain in their chairs for at least 20 minutes after eating to allow gravity to do its work, and their food is often prepared to form either a gruel-like substance or "meatballs" to help their journey to the stomach.

Sildenafil opened the sphincter of the lower esophagus for 20–60 minutes, ideal because that should only be open when a dog is eating, Haines said.

The dogs in the study were given both sildenafil and a placebo, switching halfway through the study. Their owners tracked the dogs' regurgitation episodes, but they weren't told which drug their dogs were on. However, Haines said many of the owners figured out when their dogs were on sildenafil because the medicine was working.

Sildenafil showed the most effectiveness in dogs who regurgitate frequently but not excessively, said Haines, who adds that she prescribed the medication to the dogs after the study to keep it working. It was less helpful for dogs with more severe cases because it was harder for the drug to make it into the stomach where it would be absorbed, the study says.

Other veterinarians were already asking Haines about using sildenafil for their patients, she said.

Researchers said sildenafil can also treat dog's and humans' with "elevated pulmonary blood pressure" when it's not being used for its, um, usual task.