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Colic is a scary word to horse owners and veterinarians.  However, some types of colic are much worse than other types.  While 90% of colic cases resolve with minimal treatment on the farm, some require more intensive care.  One such type of more serious colic  is small intestinal strangulation, which is an obstruction of the blood supply and the lumen (the inside of the tube, where food passes through) of the small intestine. 
GI Anatomy1. Stomach 2. Small intestine 3. Cecum
The horse's gastrointestinal system is quite lengthy - it spans approximately 120 feet, and the majority (70-80 feet) of that is small intestine.  Furthermore, it's mostly floating freely in the abdomen, with minimal attachments to the body wall and surrounding organs.  This conformation gives lots of opportunities for something to go wrong, whether that's a twist, or some other way that the intestine ends up in the wrong spot. 
 
The small intestine (or SI, for short)  is the same in horses as it is in dogs, cats or humans.  It's made up of 3 segments - the duodenum, the jejunum and the ileum.  The duodenum is the first section, just after it leaves the stomach and for about the next 12-16 inches (that's it - so, not much goes wrong with the duodenum!)  The jejunum makes up the bulk of the small intestine, and the ileum comprises the last foot or so before it enters the cecum.  There are minor variations in these structures, but we don't have to worry about them here.  All this SI is suspended within the abdomen by a sheet of connective tissue called "mesentery".  (If you laid a garden hose straight across a towel, then picked the towel up at all 4 corners it would create the same effect.)  The mesentery brings blood supply to the intestines. 

Small intestinal strangulation means that a section of SI is squeezed tightly - like wrapping a rubber band around your finger.  This tight pressure cuts off both the blood supply as well as flow through the center of the "tube" of the SI.  This process can occur a number of different ways, including masses, internal hernias, and intussusceptions (it's a tough word, we'll get to that).  All of these are surgical problems, but there are various factors which contribute to outcome and prognosis.  We'll outline the most common strangulating lesions below. 
Strangulating LipomaLipoma in hand, dead tissue to right
Strangulating lipomas: One of the more common obstructions we see, especially in older horses, is something called a strangulating lipoma.  A "lipoma" is a benign fatty tumor that develops within the mesentery.  (We call it "benign" because it's a tumor that does not metastasize to other parts of the body.  But that doesn't make it less serious.)  Lipomas typically hang from a stalk, which makes them a ticking time bomb for colic - at some point in the horse's life it can wrap itself around the small intestine, cutting off the blood supply and causing sudden, extreme signs of pain.

Internal hernias:  A "hernia" is when normal tissue slips through a normal or abnormal hole in the body.  When we talk about small intestinal herniation, we mean there is an opening that the small intestine moves through and gets trapped.  These openings can be anatomical openings (such as an inguinal hernia) or holes that have developed in other structures due to previous trauma or a defect from birth (such as a tear in the mesentery or the diaphragm).  A small, normal hole in the mesentery is called the "epiploic foramen", which can occasionally trap the small intestine and cause a strangulation. 
Intussussceptionwww.wikivet.net
Intussusception:  Prounounced in-tus-sus-sep-shun, these are more common in younger horses.  This occurs when one piece of small intestine telescopes into another piece of small intestine.  We often suspect that a heavy parasite burden leads to this disorder, however sometimes we just don't find an answer.  While this isn't truly a "strangulation", it kind of acts in a similar manner.

Regardless of how it happens, small intestinal strangulations are a serious problem.  Horses are often in extreme pain and are found thrashing.  They have elevated heart rates, oftentimes over 80 bpm and head wounds are not uncommon (from throwing themselves into the wall).  The clinical signs of associated with this are not pretty.  Further diagnostics can be done to confirm, such as a rectal exam and ultrasound, but referral to a surgical facility should be foremost on your mind. 
Dead Small intestinePink is healthy tissue. Dark purple is dead SI.
Why is it so painful?  Because the blood supply to the area of strangulated intestine has been cut off, and the tissue is in the process of dieing.  While the tissue is compromised, it is releasing toxins into the bloodstream, which further sickens the patient.  These cases become critical quickly and surgery is really the only option. 

Once the horse goes to surgery, some questions still remain.  (You can answer some of those questions at this blog.)  The tissue is not always dead, and simply removing the obstruction can allow blood to flow back into it.  If this occurs, then the tissue will regain a more normal color.  If not, then that section of bowel has to be removed, and the cut ends reattached.  This is referred to as an resection-anastamosis.  If a small section, of bowel is compromised (a few feet), then chances of survival increase.  However, if large amounts are affected, prognosis will drop quickly.  A horse can have up to 50% of its small intestine removed, but taking 30-40 feet of SI out is a risky endeavor.  Many times, the decision needs to be made whether to finish the surgery, or to euthanize while under anesthesia.

Colic on fluids
If the horse is recovered, the battle doesn't end once surgery is done.  Initial recovery for these horses requires about 2 weeks in a hospital with IV fluids, antibiotics and pain medications. Diets are slowly introduced to allow the gut to heal and not have to work too hard.  These horses have to be monitored very closely for secondary signs, such as recurrence of colic or for laminitis.

Small intestinal strangulations are one of the more severe types of colic.  Treatment must be fast and aggressive, and even then it's not always successful.  Always have a trailer readily available in case you need to transfer to a surgical facility.  Time can be critical in these situations, and an hour can make a huge difference. 


 
 
The equine digestive tract is always a concern for horse owners - and veterinarians!  Colic can be caused by many different things, and one possibility is EGUS - Equine Gastric Ulcer Syndrome.  Gastric ulcers are actually quite common in horses.  There are a variety of reasons for this, but have no fear!  While they are common, they are rarely life-threatening and can be cured with appropriate treatment.
Picturewww.egus.org
First, let's start with an anatomy overview.  The equine stomach is divided into two sections - the non-glandular (or squamous) section, and the glandular area.  The line dividing these areas is known as the "margo plicatus".  Stomach acid is secreted by the glandular area.  We typically see ulcers along the margo plicatus on the squamous side of the stomach, but we can also see ulcers throughout the non-glandular and glandular regions.  Oh yeah, and just to be clear, gastric ulcers are erosions in the normal lining of the stomach.  Pretty simple so far, right?


 
 
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The eye is a very delicate organ, and horses specifically have eyes which are in a very precarious position.  In order to allow for a nearly 360 degree view around them, horse eyes are placed well on the outsides of their heads.  This anatomic location combined with a horse's normal "flight" response makes eye injuries quite common.  One of the most common things we see are corneal ulcers. 


 
 
Every so often it happens – your horse just doesn’t seem right and you need to call the vet.  When you do, it’s important to have as much information as possible so your vet can get a good picture of what’s going on.  Here are five of the most common questions we ask horse owners – know these, and you’re one step ahead of the game!


 
 
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With the warm fall we've been enjoying, it may be hard to remember that winter is just around the corner.  Soon enough, however, we'll be battling snow and frozen ground as we take care of our equine companions.  It's important to put some thought and time into preparing your horse and your property before winter sneaks up on us completely.  We've outlined a few things to keep in mind to help this transition time be as seamless as possible. 


 
 
Recently, mosquitoes infected with EEE (Eastern Equine Encephalomyelitis virus) were found in Voluntown, CT.  Not only that, but there have been 2 confirmed cases of EEE positive horses in Massachusetts.  While it would be nice to hide from it, the fact is that it is in our backyard.  But what do we really know about it? 
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USDA map Oct. 2012
EEE is mainly found in the US east of the Mississippi river, and throughout areas of Central and South America.  The virus persists in “reservoirs” – wild animals that carry the disease such as bats, rodents, and birds.  A vector (such as a mosquito) becomes infected when it feeds on one of these animals.  Most often, EEE is maintained through a transmission cycle between birds and mosquitoes.  The mosquito then carries the virus for life and can transmit it through its saliva.  If a horse happens to be the source of the next blood meal, then they can become infected and quickly begin to show signs. 

Once infected, it takes approximately 5-15 days for signs to show up.  These signs can be very mild such as a fever and depression; or severe including blindness, stumbling, seizures or death.  Any neurologic signs could be indicative of EEE, however other diseases such as rabies must be considered as well, and a diagnosis should be confirmed via testing.  Unfortunately, a diagnosis is often obtained post-mortem.  If EEE is suspected, the state veterinarian must be contacted and the disease needs to be reported.


 
 
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When it comes to the equine eye, we often discuss common diseases such as corneal ulcers, conjunctivitis or uveitis.  We do treat these conditions quite a bit, however there are some  serious uncommon diseases that we do have to think about when considering an inflamed eye.  One of these diseases is glaucoma, which can be set off by any of the above listed issues, or by another underlying problem.


 
 
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This time of year, it's good to be a horse vet.  The weather is delightful, and we get to see lots of healthy patients for routine things - vaccines, dentistry, reproductive work.  Foals have been arriving for a few months now, and you have to admit, there is not much cuter than a newborn foal.  Cuteness aside, however, deciding to breed horses is a big decision, and not one to be taken lightly.  If this is something you have been considering for your mare or stallion, read on.


 
 
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Feeding off of our last post on nutrition (pun intended), we thought we would talk briefly about the amount that horses are fed.  When talking to clients about nutrition, we often ask "How much are you feeding your horse?"  Usually the answer is something along the lines of  "A half a scoop twice a day."  But what exactly is a scoop and is it an appropriate amount to be feeding? 

Scoops come in a variety of sizes, and we use the term pretty loosely.  It can be applied to anything from a 1/2 cup measuring cup, to a #10 coffee can, or even a shovel!  That can make it difficult to communicate to your vet  exactly how much you're feeding.  Knowing the volume of your scoop can be helpful, however different feeds have different densities.  One scoop of sweet feed does not necessarily equal one scoop of pellets. 


 
 
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Nutrition is an extremely important aspect of equine health.  We have many discussions with clients regarding this topic and decided we should write down our thoughts to share with everyone else.  (If you are one of our clients reading this, you've probably heard it before!  We did do a newsletter on it last year.)  This can be a confusing subject, so we'll try to simplify things to make  bit of sense out of all of the options that are available. So let's get started.  Bon appetit!


 

Twin Pines Equine Veterinary Services, LLP. All rights reserved.
Twin Pines Equine Veterinary Services, LLP