The vet cardiologist diagnosed Moby with a single glance. “Idiopathic cardiomyopathy,” he said. “Persians get it in middle age sometimes. It causes right-sided heart failure. Moby is very short of breath, he probably has pericardial effusion.” He talked doctor talk, though the vet knew my medical knowledge was limited to a single species, and moreover, that I was a shrink.

 The first pericardial tap was remarkably successful. Moby looked better right away, stronger and more comfortable. He gave me a puzzled stare. His outrage at the indignity of being forced into the tiny cat carrier, prodded by a stranger and having his stomach shaved was tempered by his delight at feeling almost like his old self.

There was no real cure, however, just management. Forcing pills down Moby’s throat didn’t work for him or me, so I crushed up diuretics and beta-blockers twice a day, adding the powder to his favorite moist food. Initially the ruse worked, but soon he would just look at me, saying “I know you added that powdery stuff to my food again. I’m tired of it.” For a while he tried to flee, and would run a few steps when he saw the bowl I always used to crush the medicine. But he was slow now and easy to catch.  He gave up on running. The indignity of being caught so easily was disturbing for him. We compromised. He would take the medicine tainted food if I fed it to him on a spoon. “I don’t like this crap in my food, but if it’s that important to you I’ll take it. Remember I am just doing it as a favor to you because I like you.”

All cats purr, but Moby purred for special reasons. Yes, like any cat, he purred when he was content. In addition, Moby learned to purr when he was upset. He purred to comfort himself. With some flash of insight as a kitten he realized, “I make this sound when I am happy, maybe making this sound will make me happy even though I’m upset and sad.”  The vet could never listen to his chest—the loud purring obscured the heart and lung sounds. Scholars of a future day may acknowledge him as the founder of cat cognitive behavioral therapy.

While Moby was still doing pretty well, I got sick, very sick. In the midst of a nasty argument with my wife, I developed chest pain from a spastic occlusion of the left anterior descending coronary artery. The damage from the infarction was worsened by all those complications that are supposed to happen only to other people. I spent delirious days in the CCU; sad, angry days on the medical floor. I had been a fit, healthy man in his fifties. Now I was an old man with a bad heart.

I came home, sick and weak, to a wife I now realized I despised. I felt too sick to leave her. I laid on the couch a lot; I felt like crap and the nitrates gave me terrible headaches. If I acted ill my wife tried to comfort me, mainly by talking of her bravery in managing the house while I had been away. My mother visited, fussing and intruding. She thoughtfully reminded me how she had always told me not to worry so much, if only I had listened to her like a good son then this would never have happened. “It would have been so hard for me to go to my own son’s funeral, a mother should never have to do that.”   My father talked of how worried he had been about my mother. My son was kind, but I was too good of a father to bother him with my troubles. I came to wish I knew how to purr.

The couch I laid on when I felt ill was traditionally Moby’s couch. When I lay on it he would come to me, wanting to lie on my chest. Too sick to jump, he would wait until I picked him up, then he arranged himself across my chest. He seemed to like the warmth and the rhythmic movement. After a moment he would purr, his true purr of inner peace and relaxation. Maybe he came to the couch because he wanted to remind me of his prior claim to it; maybe he just liked me. Maybe he knew I wasn’t my old self. “You look almost as bad as me, old man!” he seemed to say. Somehow I had penetrated that eternal Persian solitude normally surrounding him.

To this day no one knows how cats purr, what the mechanism is. It’s a hard thing to study: They stop purring if you cut them open or scan them or scope them, so you can never really watch the process. The calm of his purring was contagious. Not only could I hear it, I could feel it. The sound seemed to go down, down, down, several octaves below human hearing to where I could feel the vibration in my tissues and bones, and my heart.

The first few days I was home, I would slip into atrial fibrillation at times. I would suddenly get weak, and when I checked my pulse, I felt the ominous irregular pulse I had learned about in medical school. Once when I lay on the couch in atrial fibrillation, pretending to be fine, Moby joined me. I plopped him on my chest, he purred, and after a moment I slipped back into sinus rhythm.

I started reading all I could about sound, vibration and healing. On my smartphone, while I lay on the couch, I read whatever I could find on the internet. I ignored medical journals and double blind trials, and focused on those offbeat health websites my patients read. Low-pitched rhythmic sound may help tissue healing. When I talked to my cardiologist about what to expect of my recovery, he said, “Some people heal with scar tissue and have very poor recoveries, other form good muscle tissue and do really well. It’s kind of up to God.”

I didn’t trust God all that much at that point in my life, but I trusted Moby. I put that purring machine on my chest whenever I could.  After a week or two, I was back at work.

Moby never recovered. The pericardial fluid started to compartmentalize, very little would drain. The tissue had scarred, the pokes were painful. The meds stopped helping. What was inevitable became imminent. One morning he didn’t get up to greet me. He was curled up in a quiet corner of the house. I wished he would have come to me when he knew he was dying, but I don’t think he wanted to bother anyone with his troubles, that was his way.

A month or so after Moby died he came back. I had a dream; shrinks take dreams very seriously. In the dream Moby was there, as vivid as life. I could feel his warm body and his thick fur as he rubbed my leg and I stroked his head. “Moby, you came back, thank you!  Thank you!” I said in the dream. I had never really had a chance to thank him. I hope he purred happily when he died.

Greg Mahr is a psychiatrist at Henry Ford Hospital in Detroit and on the faculty at Wayne State University. "The Sounds of Purring" was chosen as an Honorable Mention in the 2016 Intima Essay Contest, “Patients, Providers and Pets: One Health for All,” a call for stories that reflect the term zooeyia, which has been coined to account for the salutary effects pets bestow upon humans.