After doing some research on the mechanisms of contraction in the esophagus, I found nitric oxide to have a role in the contraction/relaxation of esophageal muscle in several species. The dog esophagus is very different in it’s make up of smooth and striated muscle than other species. We all know Sildenafil’s effect on Nitric Oxide, so thought it may have an effect on the motility or relaxation. All of our drugs have been aimed at improving contraction in ME patients, I thought maybe just causing a difference in the tone of the muscles (even if it is through relaxation) may help move food into the stomach more easily. I prescribed Sildenafil 1-2 mg/kg q 8 to 12 hours. We did notice that it does take a few days before we saw a difference in clinical signs. I found that the regurgitation episodes to be less frequent, and mostly just liquid (little to no food). I do have the drug compounded (have been using Wedgewood pharmacy) into a liquid form so the medication is easier to give the patients. Both animals have been on this drug for greater than 6 months, and have both shown to have dramatically decreased episodes of regurgitation and have also gained considerable weight without changing feeding protocols. Neither have shown any side effects associated the medication as of yet. Radiographically the ME is still there, but the food is not getting stuck in the esophagus. So, in these two dogs it is definitely doing something to the motility, even in abnormal tissue. I would love to see if this medication is able to help others as well. It is such a horrible disease. Please keep me updated if you do decide to try it! I was hoping to get a publication out of it, but I will gladly settle for it just being able to help a few more dogs have a better life.
And honestly sildenafil has gotten a lot less expensive recently especially if you have it compounded into a liquid form at a higher concentration (100mg/ml) from a company like Wedgewood or Roadrunner. My patients are only using it twice a day. The tablets are expensive, and harder for ME dogs to swallow.
Kristen Kulinski DVM MS
Here are a link to a few papers regarding the role of Nitric Oxide in esophageal contraction/relaxation in other species:
Kristen M. Kulinski DVM MS
Cypress Lake Animal Hospital
38316 Hwy 929
Prairieville, LA 70769