The Anatomy of The Stethoscope


By Portia DeLoache DVM

 As equine veterinarians, we often demand a lot from our horse owners.  Not only do we need them to provide an accurate history and make decisions regarding medical care, we may also depend on owners to help restrain during exams.  It is common for part of the history to be given to us while we are examining the patient while the owner is holding for us.  As veterinarians, we do our best to multitask but there are limits to how many things we can juggle at once. 

One example of such a scenario happened recently when I went to see a horse for colic (belly pain).  I began by greeting the owner (a nice older gentleman, we’ll call him Mr. Drum) and asking about the recent history: why the horse was being seen (colic), how long had it been going on (about an hour), had any treatments been given (Banamine® about 30 minutes ago), and any recent changes in routine or diet (no changes).  Mr. Drum answered my questions concisely, haltered the horse (“Chubbs”) and I began my physical exam.  This normally includes listening to the patient’s heart, lungs, and gut sounds with a stethoscope which is a small piece of equipment that uses tubing and a bell (chest piece) to amplify quiet sounds and transfer them to ear pieces.  I began by checking a heart rate, positioning the chest piece behind the horse’s left elbow until I heard the characteristic “lub dub”.  Then I used my watch to start counting (1, 2…) when I heard some murmuring in the background and I looked up (still counting 4, 5…) and noticed the Mr. Drum’s mouth was moving.   I normally take a heart rate for 15 seconds and then multiple by 4 for an average beat per minute count so I finished my counting (9 x 4 = 36 beats per minute, normal) and pulled one of the ear pieces out of my ear “Sorry, what were you saying?  I can’t hear outside with the stethoscope.” I asked.  “We did get some new hay in a few days ago, same kind of hay but a new batch.”  “Good to know.  His heart rate is normal which is good.  I’m going to continue checking lungs and gut sounds” I replied.  I reset my stethoscope into my ear and listened to lung sounds on the left side and then shifted back to listen to gut sounds when I heard murmuring.  I tried closing my eyes thinking it may serve two purposes:  1) to better focus on the gut sounds which are often reduced or absent in cases of colic and 2) to let Mr. Drum know I was focused on the horse.  Unfortunately, he didn’t seem to notice.  I removed one of my ear pieces again and said “Lung sounds are good but gut sounds are quiet on the lower quadrant on this side.  Sorry, I missed what you were saying while I was listening” indicating the stethoscope.  “I was just saying he normally is a real chow hound so when he walked away from his hay this morning I knew something wasn’t right” the owner said.  I shot a sideways glance Chubbs noting his thick cresty neck and extra padding around his tail; it was true he was aptly named and didn’t seem the type to miss a meal.  I nodded and moved to his right side to continue my exam still holding the ear piece out as Mr. Drum continued.  “He pooped twice before you got here and he wanted to eat grass after the Banamine® but I didn’t let him.”  I nodded and added “that’s good, better not to add anything on his stomach until he gets checked.”  “Yes, I learned that lesson when my wife’s horse colicked last year.  She was out of town and when her horse was lying down and rolling she told me to give it Banamine® and call you guys, but after the Banamine® the horse wanted to eat so I fed her.  When I told my wife, she got so mad! I was in the dog house for about a week after that.” “Yes better safe than sorry” I nodded and wedged the ear piece back into my ear.  As I placed the stethoscope on the horse’s right side I hear several loud rapid thuds.  For a split second I was alarmed I had missed such prominent arrhythmia when I glanced up and saw

Photo Credits  : Anatomy of a Stethoscope - Image 3MTM Littman® Standris Medical Supply IncTM

Photo Credits : Anatomy of a Stethoscope - Image 3MTM Littman® Standris Medical Supply IncTM

Mr. Drum patting the horse on the opposite side of his chest.  I let out a sigh of relief and continued listening.  The owner, seeing my reaction, stopped mid pat and with a sheepish look, moved to rubbing the horse’s neck.  I returned to listening to his heart (thankfully no arrhythmia), lungs (clear), and lastly gut sounds when I heard a familiar murmuring.  I closed my eyes…still murmuring.  I squeezed my eyelids and pinched the stethoscope so the ear pieces pressed firmly in my ears (faint gassy pings but overall decreased).  I took the stethoscope completely out of my ears as I noticed the owner looking my way “Sorry I missed what you were saying.” “Sorry, you were listening” he said with recognition “I can wait.”  “I’m all done” I said and placed the stethoscope around my neck.  “I was just going to tell you he did drink water last night.  About a half bucket” the owner added.  “Good deal, his heart and lungs are normal, gut sounds are quiet with faint gas sounds.  I’ll see what he feels like on palpation and we can make a treatment plan from there.  By the way, where is your wife?”  “She’s out of town” he said with a chuckle. At the end of the day, Chubbs did great and Mr. Drum stayed well out of the doghouse.

What have we learned?

One, even though we have two ears we can really only hear one thing at a time. Two, don’t feed your colicky horse immediately after giving him Banamine® or you may end up in the dog house. And three, you can give the horses water but if mom leaves someone is going to colic.

Southern Equine Service