Infectious Disease Update – May 2017

There has been a number of reports of significant infectious disease in our area. Here is a quick summary:

EIA – Equine Infectious Anemia is a virus spread by biting insects. It can result in a very serious, and untreatable disease. When you have a Coggins’ test performed on your horse, this is the disease you are ruling out. A 5-year old racing Quarter Horse was diagnosed positive in Fort Lupton and was euthanized May 8, 2017. Since this occurred before many of the biting insects were around in large numbers, the hope is that no other horses will be affected. The barn is under quarantine for 60 days and all horses will be retested at the end of that time.

Strangles – This is a respiratory disease caused by the bacteria Streptococcus equi subspecies equi. This strep bacteria usually causes symptoms such as nasal and ocular discharge, coughing, fever and swollen lymph nodes that can rupture and drain pus. In severe cases, these lymph nodes swell to the point that they obstruct the airflow through the trachea, causing respiratory distress and even death. Rarely, it can also cause other symptoms such as colic, depending on whether the bacteria makes it to the abdomen. While we may see a couple of cases each year, this year has seen a higher than normal spread of the disease, including an outbreak at the Jefferson County Fairgrounds, home of the Westernaires Equestrian Team.

Rabies – This is a nearly 100% fatal virus that can easily spread between animals and from animals to humans. Two skunks and one fox were recently found to be positive for this disease. No horses or humans have been affected at this time. The signs associated with this disease are neurological (loss of coordination, odd behavior, sometimes aggressiveness) Another common sign is the appearance during the daytime of nocturnal animals or animals that usually hide. This disease can be prevented through routine rabies vaccination. If your horse has not been vaccinated against rabies within the last year, please call us to schedule one.

West Nile in Colorado 2016

Horse Positive for West Nile Virus in Weld County

A horse was diagnosed positive for West Nile Virus infection this week.  The virus infected his nervous system and caused it to be unable to stand and move normally.  This virus is routinely vaccinated against in our practice, and if your horse received the routine spring vaccination, should be protected against infection.  It usually takes approximately 3 weeks after a booster for the vaccination to protect your horse.  If you are not sure if your horse was vaccinated this spring, or if you are concerned that a booster may be indicated, please contact our office at 303-841-6006 or click here.



EIA (Coggin’s) Test

What is a Coggin’s test, and why do I need to get one for my horse?  

New horse owners ask about Coggin’s testing frequently, and not having one when you need it is a real headache.  The test checks for antibodies to a particular virus, the Equine Infectious Anemia (EIA) virus.  It is named for it’s inventor, Dr. Leroy Coggins.  The test is regulated by the federal government, can only be drawn by a licensed and accredited veterinarian, and must be run in a federally accredited laboratory.

There are several important reasons to get an EIA test on your horse.

  • Interstate Travel.  Most states require a negative EIA test within 12 months of entry to their state.  Usually a Certificate of Veterinary Inspection (a “Health Certificate”) is also required, and additional requirements vary from state to state.  We have current information on travel to all states as well as foreign countries.
  • Purchase of a new horse.   Our recommendation is that you get a new EIA test run when you buy a new horse, prior to concluding the purchase.  The federal government has specific regulations for managing positive horses, none of which you want to be involved with.  In addition, all infected horses eventually die from the virus, which likely makes the purchase a poor decision.
  • For Medical Diagnosis.  Horses that are depressed, anemic, running a fever that doesn’t resolve, or have other specific signs suggestive of EIA infection will have an EIA test run for diagnostic purposes.

Where do you run the EIA test, and how long does it take?

Our laboratory is federally accredited to run EIA tests, and has been for a number of years.  It is the only local laboratory in Elbert County.  We routinely run the tests several days a week, and results usually take only a few days.  In cases of an emergency (“I forgot that I needed a new one and I’m leaving this afternoon is the usual emergency!”)  we can get while you wait results for you at an additional expense.







This is what an EIA test report looks like.  

Our lab uses Globalvetlink for reporting.  The report comes to you via email as a PDF which you can open and print whenever you like.

Rabies Spreading in Our Area

It appears that the skunk population has spread Rabies virus across the Denver area this year.  To the right is the communication we received from the health department, which urges animals in contact with humans be immunized, or boosted as necessary for Rabies. This is especially important for horse owners because of the transmission risk due to exposure to a rabid horse’s saliva when putting the bit in the mouth or other activities that expose owners to secretions from the horse’s body.  If your horse had it’s booster in the last year, he or she is protected.  We consider the horse to be a “buffer” between wild animals like skunks that are infected and humans.  Call the office today at 303-841-6006 to get your horse’s protection up to date!

Please share the following message with your staff:

Over the last two months, Tri-County Health Department has responded to four incidents involving skunks with confirmed or highly suspected rabies infection in urban areas of the city of Aurora. Three of the four incidents resulted in skunks potentially exposing both humans and pets to rabies. All people and pets have received appropriate follow up and treatment. Thus far in 2016, rabid skunks have been identified in urban areas of Adams, Arapahoe, Douglas and Jefferson counties. The geographic spread of skunk rabies westward through the Denver Metropolitan Area is unprecedented.

Public Health anticipates more incidents of contact between humans or domestic animals and rabid skunks in both rural and urban settings. Your office may be responding to calls or incidents represent a potential rabies exposure, which needs to be investigated promptly. Please follow these steps:

  • Notify Tri-County Health Department at 303-220-9200 within 24 hours of any incident where a domestic animal (pet or livestock) might have had physical contact with a suspect rabid animal, including:
    • Bites by rabies reservoir species (skunk, bat, fox or raccoon)
    • Biting animal is acting sick, abnormal or has symptoms suggestive of rabies
    • Biting domestic pet dies in quarantine
    • Bites by wild carnivores (bobcat, coyote, mountain lion, bear)
  • Contact Tri-Counw Health Department prior to euthanasia if a domestic animal bit a person within the past 10 days and the pet owner is requesting euthanasia.
  • Actively reach out to clients with pets that are overdue on their rabies vaccinations and advise them to come in for a booster dose.

Spring Vaccinations keep your horse healthy!

Spring vaccinations are an important part of keeping your horse healthy. The routine spring vaccine includes protection for:

  • Eastern and Western Equine Encephalomyelitis (also called “Sleeping Sickness”)
  • Influenza (“Flu”)
  • Rhinopneumonitis (also called “Equine Herpes”, EHV)
  • Tetanus
  • West Nile Virus
  • Rabies

These are diseases that are commonly encountered in horses. Here in Colorado, the highest risks of exposure are for West Nile virus and Rabies, as well as the respiratory viruses. We immunize for these in the spring because the encephalitis and West Nile viruses are spread via mosquito bites. Protection persists through the entire mosquito season. If your horse travels to the deep south or the coasts, a second encephalitis booster is recommended in the fall to provide year round protection for these diseases. Rabies vaccine should be boosted once yearly in the horse.

Laminitis (Founder)

“My horse has foundered, what does that mean?”  Laminitis (founder) is a lameness condition that is characterized by the loss of the normal attachment of the hoof to the coffin bone.  There are a variety of causes for this disease including an episode of overeating in the grain room, hormonal causes, and as an after effect of high temperature or severe infection.  Rarely it can be caused by damaged circulation from a wound or other loss of circulation.  When the attachment of the hoof to the bone is damaged, the loss of attachment is usually most severe at the front of the hoof, which results in the most tearing at that point.  On a radiograph from the side of the foot, it appears that the tip of the coffin bone has rotated downward, creating the classic x-ray image of a foundered foot.   Traditionally, severity has been assessed by the number of degrees of difference between the front of the coffin bone and the hoof wall, termed degrees of rotation.  The more rotation, the worse the laminitis episode is thought to be, and the less likely the horse will return to normal.  Occasionally, the damage to the attachment is so severe that the entire hoof becomes detached from the bone, leading to the bone dropping straight downward with no rotation.  These are termed “sinkers”, and the prognosis is much less favorable than a horse with a less severe amount of rotation.

Laminitis can be difficult to prevent.  There are a number of metabolic events that occur when a horse develops laminitis.  In some instances, like the grain overload situation, the horse consumes a large amount of grain and as it passes through his digestive system, the grains ferment, and toxins called endotoxins are released.  These toxins alter blood flow to the foot, cause damage to the lining of the blood vessel in the laminae, and in that way damage the hoof attachment.  Laminitis can also occur after a colic episode, and the endotoxin release from the GI disturbance is thought to have a similar effect.  There are a number of stress related that are involved as well, with cortisone one of the most important.  Horses that have a cresty neck and are obese are at increased risk for laminitis because of a direct adverse effect of insulin on the laminae.  Horses with Equine Metabolic Syndrome have significantly elevated insulin levels continuously, and the effect of increased cortisone in the blood stream makes the insulin level climb higher.  Eventually, a critical level is reached, the laminae are damaged, and a laminitis episode ensues.  Horses that have PPID (Equine Cushings Disease) have persistently elevated cortisone levels in their bloodstream, which causes insulin resistance as well.  Treatment of these conditions involve weight management, dietary changes, and medication to control the PPID if it is present.



This image demonstrates the loss of normal parallel architecture between the front of the hoof and the front of the coffin bone, termed rotation of the coffin bone.  It also shows a very elongated toe and long heel with a steeper than normal angle of the bottom of the bone compared to the ground.  This is described as an elevated palmar angle.  Both issues must be addressed by corrective hoof trimming when managing a laminitis episode.  

About Mud and Horse Feet…

Horses in mud

It’s only April, and both the horses and the vets are already tired of the mud. Muddy pens means wet feet, and all of the problems that go with them. In the past couple of weeks, we’ve seen a huge increase in the number of hoof abscesses, thrush, and skin infections on pasterns and heels, all because of the muddy (and other stuff) pens the horses stand in all day.

Just like when you soak in the bathtub for too long and your feet get all wrinkly, the horse’s foot softens when standing in wet environments, making it more permeable to barnyard bacteria and contaminants. If your paddocks or pastures have gotten muddy and wet with all of this snow melt, it’s really important to clean out your horse’s feet, wash off the caked-on mud, and give your horse a dry place to stand for a while. It’s a lot easier than treating problems…

My horse has a cut… what should I do?

“My horse has a cut on his leg, what should I do?” This is one of the most common questions we hear. The critical things to know are depth, discharge, and whether important structures are involved. Wound depth can not always be determined by looking. In a typical wound, you can see hair missing, a raw spot, and maybe edges and deeper structures. If all you see is missing hair, the wound is not serious, and all that is required is to keep it clean with water. If you are able to identify complete edges on both sides of a wound, the wound is termed full thickness. Full thickness means that the skin has been cut clear through, and that structures inside are exposed to the outside. These wounds require inspection by your veterinarian, because they often are like an iceberg, bigger on the inside than on the outside. There may be tendons, ligaments, muscles or joints underneath that are damaged, and often there is debris like manure and hair packed inside. These wounds are likely to get infected and need medical management in order to get good healing. The last bit of information to process is whether or not important internal structures are involved. Wounds that involve joints, tendon sheaths, tendons, ligaments, or bone are particularly serious because infection or injury to these structures can become life threatening. These wounds can often be managed successfully if diagnosed early. Once infection has set in, it is much more difficult to achieve a good outcome. An important part of this assessment is determining how much pain the horse is in. If he is limping or unwilling to bear weight, is off feed or lethargic, it’s time to call your veterinarian.

“Does my horse’s wound need stitches?”   Wound suturing is recommended for larger wounds, wounds with a lot of injury underneath the skin, if tendons, muscles, or joints are involved, and if a good cosmetic result is desired. Usually, sutured wounds heal faster than those left to heal by themselves, with less scarring. Wounds over joints can be successfully sutured, they just require specialized bandaging to limit movement while the cut heals.

“My horse’s wound has pus coming out of it. What should I do?” These wounds are infected, usually with bacteria and debris from the skin, as well as the barnyard. Infected wounds are swollen, red, have discharge, may or may not smell bad, and are painful. These wounds are treated in two ways. First, it is essential to decontaminate the wound. This is done by applying large quantities of hypertonic saline solution to the wound to dilute the discharge. In a pinch, you can use a garden hose to decontaminate a wound. Do not apply Furacin, disinfectants, antibiotics, soap, bleach, Vetricyn, or other substances unless directed to do so by your veterinarian. Sampling of the wound for bacterial culture and determination of antibiotic sensitivity may be very important in order to get the infection resolved. Bandaging of draining wounds on legs is helpful to remove discharge and protect the raw surfaces from recontamination by the environment. The frequency of bandage change is determined by how quickly drainage soils the bandage material. It is very possible to suture wounds that have become infected once the infection is under control, using a technique called delayed primary closure.

Pain management for horses with wounds is very important. Numerous studies have shown that adequate pain management speeds and improves the quality of wound healing. It is a matter of humane treatment of animals as well. Minor wound pain is often well managed with anti-inflammatories like phenylbutazone, Previcox, or others. More substantial wounds may require opiates, local anesthetics, epidural, or other modalities to adequately control the pain.

This cut was treated with hypertonic saline solution only after a partial failure of surgical repair.  Photo is one month after the initial injury.  Notice the lack of proud flesh and infection.  You can also see the new skin growing in from the edges of the wound.

PPID Basics

PPID (Equine Pituitary Pars Intermedia Dysfunction) is a disease of the horse’s brain.  It is caused by damage to the nerves that control secretion of hormones by the pituitary gland.  Pituitary hormones include regulation for Cortisone, Thyroid Hormone, Hair growth, Urination, Lactation, and Reproduction.  Loss of control usually causes elevation of the various hormones, although sometimes it just mean loss of the normal up and down cycles that occur daily.

The signs of PPID are related to which hormones have gone out of control.  The most commonly observed ones are ACTH, which regulates body cortisone levels, MTH, which regulates hair growth, and ADH, which regulates production of urine.  As you might expect, the horse shows these problems by urinating too much, growing too much hair, or getting a large abdomen or foundering.  Horses that show the typical long dreadlock type hair are obvious.  The urination and reproductive issues must be tested for , indirectly, by looking at kidney, urine, and reproductive hormone levels.  Cortisol is best evaluated indirectly by measuring ACTH levels, although there are older tests such as the dex suppression test that can also be used.  Detecting cortisol elevations is vital because of the increase in insulin resistance it causes, as well as the direct suppression of the immune system and liver damage.

Once diagnosed, the treatment of PPID is medical, and the goal is to return hormone levels to normal.  Fortunately, we now have available a prescription medication to treat the disease called Prascend.  Prior to the availability of Prascend, we were forced to use compounded pergolide, which was shown in multiple studies to be very unreliable and unstable.  Prascend causes ACTH to go down to normal levels when dosed correctly in over 90% of the horses.  It is important to monitor the ACTH level at least twice yearly to be sure the ACTH is staying in the normal range.  There is a fall rise in the normal level of ACTH in August through December, and it is exaggerated in PPID patients.  This elevation causes an increase in insulin resistance, and is responsible for the fall laminitis episodes that occur each year.

Equine Metabolic Syndrome Basics

Equine Metabolic Syndrome (EMS) is a disease similar to Type 2 Diabetes in humans. Normally, when horses eat a meal, they absorb sugars from their intestines, causing an increase in blood sugar levels. In response, the pancreas secretes insulin, a hormone that helps glucose get into the cells where it can be used for energy. The circulating blood sugar thus goes back to a lower level. This is an active balancing mechanism.

In the EMS patient, the body becomes much less sensitive to insulin, and ever increasing amounts are required to return the blood sugar to normal. This lack of sensitivity to insulin causes a number of problems. First and foremost, there is significant evidence that chronically elevated insulin levels directly damage the lamina in the feet, causing founder. In addition, there is strong evidence of immune system damage, and increased fat deposition both externally (the crest, loin, and tail head), and internally, particularly in the liver. The internal fat is particularly damaging, because it releases various other compounds that amplify the insulin resistance.

Management of EMS in the horse is centered on dietary changes and increased exercise. Exercise is the best insulin sensitizer available. Riding 4-5 days a week for an hour is great therapy for both horse and owner. Each session should work up a sweat.

Modification of the diet to limit intake of soluble sugars is very helpful. There are broadly two types of sugars available in the horse’s diet. These sugars are classed as soluble and insoluble. Soluble sugars are things like glucose and fructose and taste sweet. Insoluble sugars are more like pasta. It is possible to measure the soluble sugars in hay and grain samples. The goal is to have less than 10% soluble sugars in the horse’s diet. Hays with more than 10% soluble sugars can be soaked for 30 minutes to remove the soluble sugars. Remember to pour out the water before you feed the hay! There are sources of low soluble sugar hay pellets and pre-formulated rations available from Purina, Nutrena, and others.

The other essential part of dietary management is total caloric intake. EMS horses need to be a little on the thin side. Normal recommendation for total caloric consumption is 1.5 pounds of feed (total hay and grain) per day per hundred pounds. If your horse is over weight, a weight loss program should be devised to get his weight down.  Remember, less fat = less insulin resistance.