can we all say OW?

diaphragmatic hernia (can anyone say ow?)
so, 2 wednesdays ago - i was on emergency duty from 5pm-11pm. this entails hanging around the vet school, fielding calls from concerned owners, and taking emergency cases as they present. around 8pm, we were informed that a dog was coming in that the owner said was hit by a car (HBC, as vets refer to it). the owner said that the dog was stable.

when he came in, the dog was panting heavily but otherwise ok. no obvious trauma, broken bones, hemorrhage, the like. we took it back to ICU, and the panting steadily got worse. the dog was obviously in shock. it was pale, breathing rapidly, and weak. the internist tapped the chest for fear that the dog had a pneumothorax (breach of the chest cavity leading to air in the chest, loss of negative pressure, and lung collapse - called atelectasis). the chest taps were negative. we were exceedingly puzzled, as the dog was obviously in respiratory distress. pneumothorax is quite common after HBC. we tapped again, and the chest tap was still negative - on both sides. we should have known what was wrong immediately after listening to the heart. in a dog, the heart sounds are loudest on the left side and much more muted on the right. when we ausculted, the heart was on the right side, and nothing was heard on the left at all. we stabilized him as best we could and prepared to take him to radiology. as we were wheeling him down there a tech suggested diaphragmatic hernia. it was like a light went on - duh! of course.

xrays confirmed it, there was indeed a DH - and a bad one. DH is exactly what it sounds like. the sudden increased pressure in the abdomen (as a result of the car hitting the dog) leads to an explosive rupture of the diaphragm. this hole in the diaphragm allows things that should stay in the abdomen to rush into the chest like there's a party goin' on and hang out there. and that's what had happened. the stomach was all the way up to the heart and had displaced it to the right side of the chest. the spleen was up there too - whoopin' it up with the stomach. the xrays were impressive, to say the least. the stomach was filled with gas and bloated, so it was easy to see.

the dog, meanwhile, was rapidly going into respiratory arrest. he was most comfortable and could breathe most when he was held upright with his front legs in the air. we're guessing that the stomach fell lower when we did that, allowing him to breathe. my rotation mate, thomas, held the dog in this position for 45 minutes, while the owner decided whether to euthanize or precede with surgery. at one point, the dog stopped breathing completely, and we had to intubate him and bag him. very ER, i know.

the emergency surgery team was called in to work on the dog, and the surgery went pretty well. however, DHs have a very high complication rate - the highest mortality is within the first 24 hours after surgery. our dog was still kicking a day later, and we had high hopes for survival. unfortunately, he died 2 days later. the heart and lungs just aren't meant to withstand that kind of trauma. barotrauma and traumatic pericarditis are 2 reasons that DHs have such a piss-poor prognosis. the abdominal contents smash up against the heart and lungs, which are just not meant to handle pressure.

interestingly enough, dogs can be born with a congenital DH, in which intestines and organs slide in and out of not just the chest but the actual sac around the heart (called a peritoneal-pericardial DH). they can live years and years before some other problem necessitates xrays and someone notices the irregular silhouette of the heart and diaphragm. the traumatic ones are the baddies...

ps - avian species lack a diaphragm and rely entirely on their pectoral muscles to breathe. thus, when restraining a bird, it is crucial to not press down on their chests, else they cannot breathe.

so yeah, that's about all here for now. i'm going to look in the mirror at my normal sized pupils and enjoy feeling not weird.