<![CDATA[Twin Pines Equine Veterinary Services, LLP - Blog]]>Fri, 02 Feb 2018 10:54:44 -0500Weebly<![CDATA[Potomac Horse Fever]]>Thu, 13 Aug 2015 15:43:30 GMThttp://twinpinesequine.com/blog/potomac-horse-feverPicture
Over the past few weeks, we have had reports of a slight increase in cases of Potomac Horse Fever (PHF) in the Northeast. While this disease is not commonly seen in Connecticut or Rhode Island, a small increase in case numbers is cause for increased vigilance and attention.  Knowledge is power, so we thought we'd go through some specific details on PHF in this blog.

Please keep in mind as we go through this information, PHF is fairly uncommon in our region.  There is a higher concentration in central New York (near Syracuse), and a much higher concentration in the Potomac River Valley, including Pennsylvania, Maryland, Virginia.  While we still watch for it in this area, we don't see or hear of many cases.

Potomac Horse Fever is caused by an intracellular bacteria called Neorickettsia risticii (side note - it used to be called Erhlichia risticii, but the microbiologists changed its name on us a decade or so ago.  You'll still see the old name kicking around, don't let it confuse you.)  Intracellular means it can only live inside a cell - it doesn't live freely in the environment.  That also means that it needs a "vector" to get inside a horse.  A "vector" is another type of animal (worm, insect, etc) which carries the bacteria and allows it to infect something else.  PHF is kind of confusing because there are multiple vectors involved.  The bacteria is carried by a small parasitic worm (fluke) that infects freshwater snails followed by aquatic insects.  The horse doesn't appear to be directly infected by the fluke, howeverRather, the horse is infected after it eats the insect which is itself infected.   (Whew!  There's a reason this is a confusing disease.  It doesn't get better from here, but try to stay with us.)   What kind of insects are we talking about here?  The list seems to be fairly broad, but can include the adult and immature forms of caddisflies, mayflies, damselflies, and stoneflies (see image to right).  
Recent work by Dr. John Madigan of UC Davis has proven that horses become infected when they ingest the flies that are infected with the bacteria.  (Read more about it here.)  Under experimental conditions, they were able to cause infection in a horse by feeding just 8 (yes, 8!) caddisflies.  Other methods including feeding the snails or feeding the organism directly did not lead to transmission of the disease.  It's important to remember that since the fly is the vector, that means the horse doesn't need to drink directly from a river or pond.  The disease can come to the horse and land in its water bucket.   

Image (edited slightly) from Merial's FAQ page: http://www.equinewnv.com/Pages/faq.aspx
Keep in mind that a horse is an ACCIDENTAL host of the N. risticii bacterium.   While there is some fecal shedding of the bacteria in actively infected horses, which can be important in seeding aquatic areas with the bacteria, there is no evidence of direct transmission from horse to horse.  So while an active case on a farm can be alarming because it indicates that the bacteria is present and infection of other horses is possible, the infected horse does not pose a direct threat to other horses.

Once a horse is infected, the bacteria enters the monocytes (a type of white blood cell), and then travels to the intestinal tract.  The clinical signs of PHF can be quite variable - importantly, the signs can vary from farm to farm and region to region, not just horse to horse.  (There is a fair amount of evidence that PHF is actually caused by several different strains of N. risticii, based on the difference in disease severity, response to vaccination, and microscopic appearance in cells.)  Technically, PHF is classified as an "enterocolitis" - this means it causes diffuse inflammation of the intestinal tract.  Fever is often (but not always) seen, and when seen it's often moderately high - in the 103-106 degrees F range.  Depression and inappetance are common, as well as mild colic and a variable degree of diarrhea.  Some horses will also develop mild to severe laminitis.  In most areas, laminitis is a rare symptom - in other area outbreaks (such as in the Potomac River Valley), it can occur in up to 40% of cases.  Laminitis is the most concerning clinical sign - often, we can control the diarrhea, fever, and resulting dehydration, but if there is severe laminitis present, it becomes difficult to treat these horses and have them fully recover. 

The one nice thing about PHF is that the treatment is identical to another disease in our area that is MUCH more common, and has slightly similar symptoms ("Anaplasmosis" aka "Ehrlichiosis" which is a tick-borne intracellular bacteria, causing a high fever as its primary clinical sign).  These two bacteria are closely related, as evidenced by the "old" name, "Ehrlichia", which is a genus they shared before the microbiologists decided to rename them all!)  Both of these bacteria are very responsive to the related antibiotics oxytetracycline, doxycycline or minocycline.  Which antibiotic we choose depends on the severity of signs, but a response to treatment is usually seen in about 12 hours after the first dose.  The diarrhea associated with PHF takes a bit more time to clear up as the gut needs time to heal.  So some supportive care (oral or IV fluids) is often necessary for the next few days if the diarrhea is profound.

Side note:  While oxytetracycline is available over the counter (for use in cattle), it's very important NOT to attempt treatment of your horse without a veterinarian.  Oxytetracycline is poorly absorbed orally in horses, and must be given IV, diluted in sterile fluid, slowly through an IV catheter.  Don't take this on alone!

Like Anaplasmosis, a diagnosis of PHF can be made based on a blood test, most commonly an IFA (indirect fluorescent antibody) titer.  PCR and ELISA tests are also available.  Testing has its pros and cons, and can sometimes not yield expected results.  Often, clinical signs are suggestive enough to start treatment before a blood test is complete, and we generally have confirmation that treatment is successful before we have a positive blood test.  But it's nice to have a positive test, especially in an area (like ours) where the disease is uncommon, so we know that the farm has a higher risk than the general area.

Prevention of PHF is actually trickier than it would seem.  First off,  completely avoiding aquatic environments altogether isn't really feasible, especially with a trail horse.  Reducing fly populations on your farm can be beneficial (check out our newsletter on that!)  Additionally, keeping lights turned off around barns at night can help, since these lights attract insects and may lead to an increase in potential transmission. 

There is a vaccine, but it's of variable effectiveness.  We do vaccinate horses in our region who seem to be at higher risk (those horses who live in a paddock with a pond or stream in it, or who commonly trail ride in wet areas, or drink from ponds or streams).  Since the vaccine isn't particularly protective (only reaching about 78% protectiveness in experimental studies, and certainly less than that in actual infections), and the effect of vaccination wanes quickly (reaching about 50% protective at 6 months, and about 33% after 9 months), if you're going to vaccinate, it's best to do so about a month before cases start to emerge in the area.  For the northeast, we start to see cases in July/August, so vaccinating in June makes the most sense.  There is some evidence that the vaccine is waning in effectiveness over the past several years, and in some region it seems to be much less effective than in others.  This lends support to the idea that we are actually seeing several different strains, and the vaccine may be effective against some, but not others.  It's also believed that since the disease is contracted orally, vaccines may need to be reformulated to provide better protection.  

In summary, PHF is a confusing disease, and can be difficult to deal with.  Fortunately, it's not common for our area.  The vaccine may be of benefit for high risk farms, including those who have seen definitive cases.  If your horse goes off feed or just seems "off", take a rectal temperature - ask us how to do it at your next appointment if you're not sure.  If there's a fever (temperature of 102 or higher), give your vet a call.  There are many, many reasons for a horse to have a fever, but PHF will be on the (long) list of possibilities this time of year. 

<![CDATA[Equine Cushing's Disease]]>Wed, 26 Nov 2014 13:44:56 GMThttp://twinpinesequine.com/blog/equine-cushings-diseasePicturehttp://illuminationstudios.com/
Equine Cushing's disease is a fairly common term in the horse industry.  That's because 1 out of 5 horses over the age of 15 have the disorder.  But for how common Cushing's is in horses, there remains a lot of misunderstanding about this condition.  In this blog, we'll try to make things a little more clear!

While Cushing's disease can contribute to other metabolic disorders (such as insulin resistance), we're going to focus solely on Cushing's disease for the purpose of this post.   We'll tackle insulin resistance in another blog post!

The term Equine Cushing's Disease was coined for the similarity to the syndrome in humans and dogs.  (Cushing's disease in humans was originally described by a neurosurgeon at Johns Hopkins University named Harvey Cushing.)  In humans and dogs, Cushing's is most commonly caused by either 1) an adrenal tumor or 2) a tumor in the anterior lobe of the pituitary gland which causes hyperplasia (excessive growth) of the adrenal gland.   Both of these cause an increase in cortisol (a steroid).  In horses, Cushing's is primarily due to a tumor in the intermediate lobe of the pituitary gland, but there is no associated hyperplasia of the adrenal gland.  That's why the technical name of it is Pituitary Pars Intermedia Dysfunction (PPID).  Whew!  If you thought that was scientific, just wait!


So what exactly is going on to make this disease such a concern?  Well, as the pituitary tumor grows, it secretes a hormone called ACTH (Adreno-Cortico-Trophic Hormone.  Yes, it's a mouthful!)  This hormone signals the adrenal gland to secrete cortisol, also known as a "stress hormone".  The chronically increased level of steroids in the body wreaks havoc on the balance that the system usually tries to attain.  This is what leads to the common signs of PPID. 

The most common sign of Cushing's is excessive hair growth and inability to shed out appropriately (known as hirsutism).  This can affect up to 80% of horses with Cushings.  Other things we often see are lethargy, weight loss/muscle wasting, recurrent infections (such as hoof abscesses) and chronic laminitis.  If we see horses with these signs, we may recommend further testing.  However, in some instances, clinical signs are obvious enough, and we will merely recommend to start treatment. 

Testing for Cushing's can be done in a few different ways, but they mainly focus on circulating levels of ACTH.  You might say, "Well, if cortisol levels are increasing, why don't we just test for that?"  Glad you asked!  In the past, horses with PPID have shown cortisol levels that are either increased, normal or decreased.  Cortisol fluctuates throughout the day and from one individual to another, so it is very difficult to make an accurate assessment of any disease process by associating with steroid levels. 

So on to the tests we do use!  The first (which we typically rely on) is to test the resting ACTH levels.  This is simple enough - if the measured level of ACTH is above or below a certain threshhold, the horse is positive or negative, respectively. Caution must be used with this as there is a 3-fold increase in the fall, but this has been measured in normal horses, so we can adjust values for that.  The second test is known as a Dex Suppression Test, whereby a blood sample is taken, then a small amount of dexamethasone (a steroid) is administered.  A second blood sample is taken approximately 20 hours later.  This test should cause a significant drop in the amount of ACTH present.  If it does not, then the horse is positive for Cushings disease.  However, this test can be concerning as we are giving steroids to a horse with possibly high circulating levels of steroids.  Since excessive levels of steroids can rarely cause laminitis, we reserve this test for specific cases.
If results of the resting ACTH are not significantly elevated, we can do an additional test to rule the disease in or out.  This is called a Thyrotropin Releasing Hormone Stimulation test (TRH Stim for short).  This test is similar to the dex suppression test in that a sample is drawn, the TRH is administered, and a second sample is drawn 10 minutes later.  Again, we will be looking at ACTH levels and how much they rise after administration of the hormone.  This gives us a very reliable test to determine the presence or absence of Cushings disease, without the added risk of giving Dexamethasone to a potentially laminitis-prone animal. 

If we have successfully diagnosed Cushings disease, or just suspect it based on clinical signs, treatment includes a combination of medical therapy as well as management.  Currently, the only approved drug for Cushing's Disease is Prascend® (pergolide).  This is a daily medication that will need to be given for the remainder of the horse's life.  This drug aims to reduce the amount of circulating ACTH, thereby decreasing cortisol levels.  We often see a quick turnaround with horses once we start them on Prascend - owners will often comment that their horse seems to have "dropped 10 years" a month or so after treatment starts.

For a long time, pergolide was only available as a compounded formulation.  Now that we have an FDA approved form, we don't recommend or even dispense the compounded drug.  This is because studies have shown that compounded pergolide is not stable and does not have a very long shelf life.  The concentration of compounded drugs is also quite questionable and is not always what the label states.  For more on the discussion of Prascend vs. compounded pergolide, you can read our blog from when Prascend was first introduced.  Check out this study published in the Journal of the American Veterinary Medical Association on stability of compounded pergolide. In addition, compounded pergolide is no longer allowed under FDA rules.  

The other aspect of treating Cushing's is management.  Since Cushing's disease will often lead to insulin resistance (again, more on that in another blog!), it is usually important to control the intake of starches and sugars in the diet.  These horses should obtain most of their calories from low-starch hay and fat (since fat is a much safer form of calories than starch/sugar for horses with metabolic conditions).  An appropriate diet should be outlined with your veterinarian for best results.  Appropriate foot care is important, to reduce the incidence of hoof abscesses and laminitis.  Finally, horses with Cushing's disease should always be managed more carefully with regards to wounds, parasite control - their immune system is often not 100% normal due to the effects of cortisol, so they will always be prone to chronic infection, non-healing wounds, or higher parasite burdens.  Your veterinarian can help you come up with a plan to reduce these risks.

While Cushing's disease is common and incurable, it can be successfully managed.  Through owner and veterinary diligence, we can help keep these horses happy and relatively healthy for many years. 

<![CDATA[Large Intestinal Colic: Part Two]]>Fri, 03 Oct 2014 10:38:19 GMThttp://twinpinesequine.com/blog/large-intestinal-colic-part-twoIn our last post, we discussed (mainly) non-surgical types of large intestinal colic.  However, as we all know, sometimes colic goes beyond what we can treat in the field and referral for surgery is necessary.  Typically, these result from the colon moving (or displacing) into a place that it shouldn't be.   That being said, some of these can be treated medically, however not always successfully.  Since we've already gone over the anatomy of the large colon, (See Large Intestinal Colic: Part One) let's jump right into what might have happened if your horse's bowel becomes blocked. Picture
Right Dorsal Displacement: The left colon is quite mobile and likes to get stuck in places.  In a right dorsal displacement (RDD), the left colon slides around to the right side of the abdomen and gets stuck between the cecum and the body wall.  The pelvic flexure (the U-shaped area at the top of the picture) moves from the back end of the abdomen (near the rectum) to end up near the diaphragm.  This is all kinds of crazy!  The large intestine becomes partially occluded and gas distended.  In practice, we can see this occur in conjunction with a pelvic flexure impaction.  Generally speaking, the blood supply remains intact so the bowel remains healthy.  We can sometimes treat these with fluids and withholding feed, but often times surgery is required.  At surgery, the colon just needs to be decompressed and repositioned into the appropriate anatomic location.  As long as nothing more serious is going on, these horses recover quite well. 

Left Dorsal Displacement:  Again, the left half of the colon goes for a walk-about.  This time, it slides up along the left body wall and gets hung up between the spleen and the kidney.  Why?  Well, there's structure there called the nephrosplenic ligament - merely a tissue attachment between the spleen and the kidney.  (That's also why the other name for this type of displacement is a "nephrosplenic entrapment".)   The problem is that this ligament can act like a hammock for the large colon.  And we all know how hard it is to get out of a hammock!  Feed material may still be able to pass through initially, but gas buildup and the excess weight on the spleen pushes that organ out of position as well.  This can be quite uncomfortable, as you can imagine.  Medical therapy with phenylephrine (given slowly intravenously) can sometimes to shrink the spleen allowing the colon to "fall" off the nephrosplenic ligament (usually assisted with trotting or trailering the horse), however is not usually successful.  Attempts are sometimes made to anesthetize and "roll" a horse to try to dislodge the spleen as well, but this is difficult for many reasons.  Surgery is sometimes required (we estimate 50% of these colics require surgery), and again aims at merely emptying the colon and putting it back where it belongs. 

Colon Torsion or Volvulus: (Above) This is one of the scariest types of large intestinal colic.  Imagine a line drawn along the length of a horse through the chest and out the back end.  Then we take the large colon and twist it around this line, spinning it on its axis.  That is a volvulus, and while they commonly rotate clockwise, it can go in either direction.  If the colon rotates >360 degrees, blood supply will be cut off and significant injury to the bowel occurs.  This generally results in a poor prognosis and requires euthanasia.  However, if it is less than 270 degrees rotated, the colon is usually ok and just needs to be twisted back around that rod.  This is more common in broodmares post-foaling as there is a large amount of space left in the abdominal cavity after the foal is born.  Surgery is required to correct a volvulus. 
Cecal Impaction:  In the previous post, we mentioned pelvic flexure impaction.  While this is probably the most common area for an impaction, it is not the only area where an impaction can occur.  The cecum is another structure that can become impacted, and medical treatment can be difficult.  Initially, horses with cecal impactions have intermittent colic which can become more severe if it is prolonged in course.  Surgery is often recommended to removed the impaction, especially if medical therapy is not successful.  Prognosis if surgery is performed is fair, as success rates are about 70%.  The success rate rises to 80% if these cases are able to be treated medically.    

Enteroliths:  An enterolith is a concretion that forms in the GI tract.  The term broken down is entero (GI tract) and -lith (stone).  It is very uncommon to see this in the Northeast where we are, but can be seen in areas such as the southwest and Florida.  It's unclear what causes these to form, it often occurs in horses with higher mineral concentrations.  Feeding of alfalfa hay has been attributed to this higher mineral concentration. 

The problem with enteroliths is that they can grow large enough to plug up the GI tract.  Not only that, but they can abrade the lining of the intestine.  Imagine if you had a boulder rolling around in your gut!  Horses will typically show recurring colic signs, but can become extremely painful when the lumen of the intestine becomes blocked.  Surgery is required to remove these, but prognosis tends to be quite good.

The colon is a complex structure in horses and as such causes many problems.  Some of these can be treated easily on the farm, but sometimes they require referral for further care or surgery.  The choice on whether or not to do surgery should be made prior to any problems occurring, as it can be an emotionally and financially draining endeavor.  That being said, depending on the issue, large intestinal colic surgery does usually carry a good prognosis. 
<![CDATA[Large Intestinal Colic: Part One]]>Wed, 10 Sep 2014 15:58:53 GMThttp://twinpinesequine.com/blog/large-intestinal-colic-part-onePreviously, we have discussed small intestinal colic and gastric ulcers.  However, when discussing colic, we have to determine if it is small intestinal in origin or large intestinal. 
Below is a brief list of problems associated with the large colon.  Typically, these are non-surgical and can be resolved with some medical management.  That's not ALWAYS the case, but for the most part it is.  (Part 2 will focus on more severe types of large intestinal colic.)

The large intestine begins as the ileum (the last section of the small intestine) enters the cecum and is approximately 40 feet long.  The cecum is a blind sac that is shaped like a "C" and is a big fermentation vat.  The curvaceous colon then takes a bunch of twists and turns after it exits the cecum.  First, it becomes the right ventral colon.  It changes into the left ventral colon and takes a big, narrow turn (the pelvic flexure) into the left dorsal colon.  It then turns again to become the right dorsal colon.  But we're not done yet!  From here, the intestine narrows into the small colon and finally the rectum, which is the last foot or so of the colon.  Whew!  With all of that crammed into a space about the size of a 33 gallon trash can (along with all the other organs!), what could possibly go wrong?  Let's find out!
Gas/Spasmodic Colic:  With all of the fermentation that goes on within the large intestine, a lot of gas is produced.  Occasionally, the colon can become a little distended and uncomfortable.  These will often correct themselves with a little bit of time and maybe some pain meds.  Please remember to contact your veterinarian and discuss this with them, as it could be something more serious.  Sometimes, simply walking horses for a bit can help things move along and uh, expel the gases.  Just remember, we want to walk them for a bit then let them rest.  Walking non-stop does nothing more than exhaust yourself and your horse. 

PicturePelvic Flexure (www.studyblue.com)
Impactions:  Another common finding are pelvic flexure impactions.  These occur because this is an area of the LI that narrows significantly.  When horses become a little dehydrated, the feed material binds together more easily and gets stuck.  We find these happen more frequently during cold weather as horses tend to drink less. 

Other types of impactions include cecal impactions, where a large amount of feed material becomes trapped within the cecum, and small colon impactions, which tend to be more common in miniature horses.  These can be more difficult to treat, but still follow the same pattern as pelvic flexure impactions. 

The mainstay of treatment for any of these is fluids, fluids, and more fluids. Absolutely no food should be given to horses with an impaction (or any colic for that matter), as it will continue to build up and make the impaction harder to move.  Many times we can pass a tube and administer oral fluids to get everything moistened up and moving again.  Other times, we may need to re-hydrate the patient with a combination of IV and oral fluids.  Occasionally, these can become severe enough to require surgery. 

Horse in sandy pasture
Sand Colic:  Sand colic occurs when horses are fed on sandy ground.  As they eat their hay, they also take in sand particles.  This sand then sediments out in the ventral colon and sits there.  While laying against the wall of the intestine, it can cause severe irritation and lead to diarrhea. The more that builds, the more uncomfortable they can become.  The sand can even become impacted, which may require surgery.  The best bet for these is prevention, by either feeding in a hay feeder or placing a rubber mat over sandy ground and feeding on that. 

If you're not sure if your horse has ingested sand, here's a simple way to find out!  Grab a couple of fecal balls (make sure there's no obvious sand stuck to them) and put them in a ziploc bag.  Add water and mash up the fecal balls.  Then hang the bag on an angle, so one corner points down.  After 5-10 minutes, come back and check it.  The sand, if present, will sediment into the corner of the bag.  Sometimes you can see a thin layer of it, other times you nee to squeeze the corner between your fingers and feel the gritty texture.  If you notice any, you may want to consult your vet for treatment options and consider changing where/how you feed.
As already mentioned, if you think your horse is colicking, all food should be pulled.  We don't want to make a bad situation worse.  Horses can be off feed for quite a long time with few ill effects.  The next thing to do is contact your veterinarian.  We don't recommend administering medications prior to calling.  This is because if we do need to come out, medications can mask signs that might help with a diagnosis. 

Stay tuned for Part 2 where we'll discuss more serious and surgical types of large intestinal colic. 
<![CDATA[Small Intestinal Colic: Strangulating Lesions]]>Wed, 09 Apr 2014 12:12:13 GMThttp://twinpinesequine.com/blog/small-intestinal-colic-strangulating-lesionsColic 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. 
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. 

<![CDATA[A Pain in the Gut:  Equine Gastric Ulcer Syndrome]]>Mon, 03 Mar 2014 13:23:05 GMThttp://twinpinesequine.com/blog/a-pain-in-the-gut-equine-gastric-ulcer-syndromeThe 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?

PictureUniversity of Kentucky
So, why do horses get ulcers, anyway?  Well, horses are designed to be grazers, therefore they are continuously secreting acid into their stomach.  This is different from humans who secrete acid in response to a stimulus (such as smell of food or eating a meal).  Saliva is alkaline (high in pH), and usually balances the acid (low in pH).  The trouble is, horses tend to only salivate when they are eating.   As humans, we often put horses on our schedule for feeding - a big meal at breakfast and dinner, and maybe a bit at lunch time, too.  We have also moved to feeding them large amounts of grain, in order to get sufficient calories into them in a short period of time.  A high grain diet increases acid production, as well.  Long term drug administration (such as Bute) can also negatively affect the stomach.  Lastly, horses are easily stressed.  While high workloads are usually to blame (racehorses can have up to 90% prevalence of ulcers), something as simple as pecking order in a herd can be stressful enough for some horses.  So, just because your horse is a pasture potato, that doesn't mean he can't develop ulcers. 

While not all horses with ulcers will show clinical signs, when they do, the signs tend to be vague.  Many times, horses will show intermittent bouts of mild colic.  They may look at their sides occasionally.  Attitude changes often occur and they can become nippy or unwilling to work.  "Girthiness" may be noted - where pressure applied to the girth area causes them to be uncomfortable.  Weight loss and poor appetite are also sometimes seen.  Since the signs are vague, a full workup is often recommended to rule out other diseases. 

The best way to diagnose ulcers is by endoscopy.  Endoscopy is performed under standing sedation.  A long, flexible camera is passed up the nose and nasal passages, down the esophagus and into the stomach.  (Note that horses have to be fasted for this in order to allow for a full exam of the stomach)  This gives us a full view of the lining of the stomach.  We can then grade the severity of ulcers on a scale from 0 to 3.

Severity of Ulcers (from right to left): Grade 0 (normal, healthy stomach) to Grade 3 (Extensive ulceration)
Once ulcers have been diagnosed, we can then begin treatment.  The best (and proven) treatment for gastric ulcers is GastroGard.  GastroGard is omeprazole which is specially formulated to be absorbed by the equine GI tract.  While there are a lot of products out there claiming to contain omeprazole and cure ulcers, none of them have a protective coating to get through the stomach acid to be properly absorbed - except for GastroGard.  Also, if you're using any type of compounded omeprazole that is purple, you might as well squirt it on the ground.  This means the drug has become oxidized and is no longer effective.  Here's a study that compared the efficacy of  GastroGard with a compounded omeprazole product.  While this sounds like an ad for GastroGard, we believe that if you're going to use omeprazole, this is the only one that should be used.  You can learn more about it at www.equinedrugfacts.com

Since GastroGard is pretty darn expensive, it's not always a financial option for every horse owner.  If that's the case, we do have other tricks up our sleeves.  One alternative drug we can use is Ranitidine.  Ranitidine actually works so well to "take the burn out" of gastric ulcers, that we often use it as a first line of treatment in an acute episode of colic caused by gastric ulcers (sometimes in combination with GastroGard).  The trouble with Ranitidine is that it doesn't work quite as well for long term healing of gastric ulcers - so we sometimes have to give it for longer, and recurrences are more likely.  It also has to be given three times daily, instead of the once daily dosing of GastroGard.  But, given these drawbacks, it can be a fair alternative to GastroGard for a more economical price.
PictureNot THAT Alfalfa!
We can also make management changes to help reduce the incidence of gastric ulcers, or to help prevent their recurrence.  These changes can include offering free choice hay, reducing grain rations, increasing turnout, or changing herd dynamics as necessary.  Studies have shown that offering a flake of alfalfa hay about 30 minutes prior to a grain meal can reduce the incidence of gastric ulcers.  Along this same line of thinking, there are several "buffering" gastric supplements available over-the-counter, which can be of some benefit.  Please note, if you're considering adding a gastric supplement to your horse's regimen, check with your vet first.  There are MANY of these types of supplements available, and some are not worth the bucket they are packaged in!

While gastric ulcers are a singular cause of colic, they are probably one of the easier ones to treat.  With appropriate diagnostics and treatment protocols, we can quickly get your horse back to normal and back to doing those activities that you both love. 
<![CDATA[Corneal Ulcers in the Horse]]>Tue, 11 Feb 2014 14:55:35 GMThttp://twinpinesequine.com/blog/corneal-ulcers-in-the-horsePicture
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. 

PictureThornwood Equine
A corneal ulcer is an abrasion of the cornea that removes a portion of the top couple of tissue layers.  A majority of the time, ulcers are induced by some traumatic event.  They can be classified as simple (superficial) or complex.  Either way, they are very painful (have you ever scratched your eye?) and you typically only see a swollen, weepy eye.  It's important to note here that if you encounter this in your own horse, you should contact your veterinarian.  Attempts to look into and/or treat an eye on your own could lead to further damage.  Eyes are always an emergency. 

When your vet arrives, they will most likely sedate your horse and perform a couple of nerve blocks.  These nerve blocks temporarily take away the sensory and the motor abilities of the skin and muscles.  Once this has been performed, the horses tend to be a bit more relaxed and allow for
full examination of the eye. 

Ulcers are not always readily visible on an initial exam.  Sometimes we will see a white "spot" on the cornea, but other times nothing is really noted.  That is why we need to stain the eye.  A small amount of fluorescein stain (a green dye) is applied topically to the eye.  This stain will adhere to exposed connective tissue in the cornea, and allows us to fully see the size and depth of the ulcer.  If necessary, some debridement may be performed to remove any loose edges of the ulcer prior to initiating treatment. 

Treatment of superficial ulcers is aimed at reducing pain and minimizing infection.  Oral bute or banamine is usually given for pain management.  Topically, ophthalmic antibiotic ointment can be administered to help fight off any bacterial infection.  Atropine, a mydriatic, dilates the pupil to decrease muscle spasm and pain within the eye.  A weeklong course of this therapy is generally enough to combat a simple corneal ulcer. 

One drug you never want to use on an ulcer is a steroid.  A steroid (such as Prednisolone or Dexamethasone) eliminates the body's defense mechanisms and can make the situation much worse in a short amount of time.  So do NOT use steroids in an eye unless directly told to do so by your veterinarian! 

PictureUniversity of Pennsylvania
If severe trauma occurs, or a simple ulcer is not tended to, a more complex ulcer can form.  These ulcers tend to affect more layers of the cornea.  One type is called a "descemetocele".  (Deh-seh-met-o-seel) (Descemet's membrane is the second to last layer of the cornea). These tend to appear as white opacities with a black spot in the middle.  That black spot means that there is only one cell layer left between the outside world and the inside of the eye.  If we were to stain this eye, we would see a rim of green dye with a black hole in the middle.  Ulcers such as this put the eye in grave danger of rupturing and need to be treated more aggressive therapies, sometimes needing hospitalization.

Remember when we said eyes are always an emergency? And remember when we said do NOT use steroids?  That's because the ulcer can become "melting" - which is pretty much what it sounds like.  Melting corneal ulcers are very complicated and difficult to treat.  They occur due to heavy bacterial and/or fungal populations that are using enzymes to break down the cornea tissue.  This causes the cornea to literally 'melt' and slide off of the eye.  While a very scary situation, the eye can often still be saved with aggressive treatment.  These ulcers require diligence on the part of the owner and veterinarian. 

The cornea in the horse is a very fragile structure, but it has great capacity to heal.  Early detection and treatment of problems is necessary to have a successful outcome.  If you have any concerns at all regarding your horse's eye, contact your vet.  We'd rather look at something like what's at the top of this post than at the bottom. 

<![CDATA[5 Questions to Know the Answer to (when you call the vet)]]>Wed, 13 Nov 2013 16:40:04 GMThttp://twinpinesequine.com/blog/5-questions-to-know-the-answer-to-when-you-call-the-vet 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!

How long has it been going on?

When was the last time your horse was normal?  Depending on what is going on, duration can have a significant effect on outcome.  Problems that have been going on for some time may be easier to diagnose, however prognosis can often decrease if a situation persists for too long.  The sooner we can begin treatment, the better chance we have of a return to normal. 

How is his/her attitude and appetite?

You know your horse best, so it’s important to express how you believe he’s feeling.  Is he normally whinnying and running to the gate for his dinner, but now he’s standing in the corner with his head low?  This could be a sign of illness.  Horses also love to eat, and when they stop eating, this is often a cause for concern.  Decreased appetite or a quieter than normal attitude can be a sign of many things, but this sign may be an important piece of the puzzle. 
What is their heart rate?

The normal heart rate of a horse is 28-42 beats per minute (bpm).  This can vary a little bit, and excited horses may get up to 60 bpm.  An elevated heart rate can mean several things, but we usually think of dehydration, anemia or pain.  Dehydration leads to a decrease in blood volume, causing the heart to beat faster to compensate.  Similarly, in anemia, a decrease in red blood cells causes the heart to pump faster.  Pain can lead to rates of 60-100 bpm.  When we begin to see heart rates approaching 80-100, this can indicate severe pain or vascular compromise.  This can change the urgency of a situation.  A lot of information can be gleaned from the heart rate, so be sure to have that number ready when you call.  If you’re not sure how to take a heart rate, ask your vet the next time he or she is out! Or you can check out this article from The Horse for more information

What is their temperature? 

The normal temperature range of a horse is 99° F to  101° F, but some horses may run a little cooler (such as 98°).  An elevated temperature may not necessarily be a fever - a horse that has just worked or been trailered may increase their temperature a small amount.  Given this leeway, we generally say a fever is anything above 102° F.  Fevers are tricky because they can point in many different directions.  Twenty percent of fevers in horses go undiagnosed.  The ones we do diagnose are usually caused by infectious disease (like anaplasmosis) or inflammation (such as enteritis).  Keep in mind, as well, that various treatments can lower a fever, so it’s best to talk to your vet before initiating any type of treatment.  Here is some more information from the AAEP on this topic.

Have there been any changes in routine or management?

Did you just move to a new barn?  New load of hay or other change in feed?  It’s possible that this sudden change is contributing to your problem.  While we may not notice any problems with the hay or grain, horses can be picky eaters, sometimes for good reason. Sudden changes in feed or environment can wreak havoc on the horse’s internal systems, often by upsetting the normal gastrointestinal bacterial population.  An alteration of routine (new barn, new feeding schedule) can cause stress, which can lead to ulcers or behavioral problems. 

As veterinarians, we need to accumulate as much information as possible to paint a clear picture of the problem.  Animals do talk to us, but in a different language.  All of these questions give us tools to help decipher that language and figure out what is going on, and lead us to a resolution.   

<![CDATA[Winterizing Your Horse]]>Tue, 22 Oct 2013 15:24:02 GMThttp://twinpinesequine.com/blog/winterizing-your-horsePicture
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. 

First, take a look at your horse's diet over the winter.  At this time, grasses are starting to die off, and it will become important to add in hay as the main roughage source (as long as your horse can appropriately chew hay, that is!).  If you have ordered a large amount of hay, consider having it tested for nutrients.  (You can send hay to Equi-Analytical, in Ithaca, NY for full analysis.)  This information can help your veterinarian and/or nutritionist properly balance your horse's ration.  Also, take care to slowly switch your horse's diet, instead of abruptly adding a different roughage source.  Any sudden change in your horse's diet can increase the risk of colic.  While changing hay is not thought to be as drastic to the horse as a change in grain, it certainly can upset the digestive system. 

Dr. Leighton performing a dentistry
To be sure that your horse can appropriately chew a coarser diet over the winter, a little attention to their teeth is in order.  Oral examinations by a veterinarian are recommended once yearly for all horses, and fall is a great time to schedule that exam.   This exam should be performed with a full mouth speculum - this allows for a visual as well as manual exam (meaning all teeth should be looked at as well as palpated).  Loose teeth may need to be extracted, or a wave/step mouth may need to be adjusted to allow your horse to be able to chew more properly.  Many older horses develop a "smooth mouth" as they age, which reduces the grinding surface of their teeth.  These horses will need alternative roughage sources, such as soaked hay cubes/pellets, or chopped hay.  An oral examination will allow your veterinarian to make these diet change recommendations. 

Preparing your horse's feet for winter is another important consideration.  Many people plan to pull their (normally shod) horses' shoes over the winter, since they won't be riding as much.  This is a fine plan, as long as your horse's feet are tough enough to stand up to rough conditions.  Be aware, however, that your horse's feet will take a few weeks to toughen up after shoes are removed.  Light riding, turnout on softer ground, and avoiding rough/rocky footing is important while your horse adapts to being barefoot.  If you choose to maintain your horse in shoes over the winter, consider some adaptations to these shoes to help provide traction in icy and snowy conditions.  Snow pads are sometimes helpful in reducing "ice-balls" which can build up within a shoe.  The addition of borium to the bottom of the shoe can increase traction on ice - but be aware that this is a trade-off with potentially increase in strain on soft tissue structures.  If your horse is normally barefoot, you're not off the hook - pay attention to how the feet are reacting to firmer ground or icy conditions as the winter sets in.  Hoof boots can be helpful in protecting your barefoot horse's feet from very hard, frozen ground. 

Fecal egg counts
Another preventative health care consideration for fall is deworming.  As most regular readers of this blog will know, we advise routine fecal egg counts to check for parasite burdens and make deworming recommendations based on those counts.  But even if we NEVER see an egg in your horse's sample, and your horse never leaves the property, we still recommend deworming at least once a year, and we do that in the fall.  The reasons behind that recommendation could be a whole 'nother blog - but suffice it to say that horses tend to have lower egg counts when they are dewormed correctly in the fall.  We typically recommend either an ivermectin or moxidectin product in combination with praziquantel - but always feel free to chat with us regarding what is best for your horse. 

Finally, take a look at your property, barn, fencing, and any other structures that your horses will be exposed to this winter.  Is everything structurally sound?  Is the roof on the barn ready for a few feet of snow?  Can your fencing withstand a Nor'easter?  How about that dead tree in the paddock that's been threatening to come down all year?  Now is the time to make adjustments to your barn and paddocks, before icy conditions make repairs much more difficult. 

With a bit of forethought, this winter can be a breeze for you and your horses.  Taking a few minutes now can save you time and frustration in January - and you can use that time to sit by the fire with a cup of hot chocolate and a good equine magazine in hand!   We wish you all a peaceful fall, and a safe and snug winter season (when it comes, that is.  Let's not be TOO hasty!)

<![CDATA[The Threat of EEE]]>Sat, 31 Aug 2013 18:11:45 GMThttp://twinpinesequine.com/blog/the-threat-of-eee 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? 
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.

EEE is usually fatal in horses (75-100% mortality rate).  They are considered dead-end hosts as there is typically not enough virus in the blood to infect another mosquito.  This means that transmission from horses to humans, or even to another mosquito, is extremely unlikely.  That being said, in acute infections, circulating virus can be high and outbreaks can occur in a horse-dense population.   

The disease is seasonal and usually lasts from July to November in this area.  It is mainly dependent upon the mosquito population, as they are the main vector.  Warm temperatures and standing water promote mosquito reproduction.   

Treatment for EEE consists of supportive care.  There is not a cure for this disease.  The best thing for EEE is prevention.  Be sure that your horses are vaccinated.  While vaccines are not always 100% effective they do lessen the severity of the disease.  If your horse is vaccinated by a veterinarian, and your horse becomes infected, most drug companies carry a guarantee on that vaccine which will help with the finances of treatment.  In this area, horses should be vaccinated yearly against this virus.  We recommend the vaccine be administered sometime in the spring, prior to peak season.

It’s also important to control mosquito populations on your farm.  This can be tricky, but simple steps can be taken including using fly sheets, or just removing old tires from your property.  Old tires and items that collect standing water are breeding grounds for mosquitoes, so removing them greatly reduces your risk.

Eastern Equine Enecphalomyelitis is a scary disease, for humans and horses. Unfortunately it appears that it is becoming a more prominent disease in our area.  Be sure to take measures to protect yourself as well as your horses, and always keep that fly swatter handy.