SPRING 2006 NEWSLETTER

RHINO-EQUINE HERPES VIRUS

With the recent outbreak of the neurologic form of equine herpes virus in the Mid-Atlantic area, everyone is pondering the best prevention and control methods. Most of these cases have been at race tracks and training centers, but some cases have been reported on farms. The neurologic form of herpes (rhino) is not well understood. It usually occurs several weeks after an animal has been exposed to the virus and has had a mild upper respiratory condition. The infected animal then usually runs a mild fever for a few days, appears to recover, and then begins to show the neurologic effects of the disease. The most usual signs of this form are weakness in the hindquarters, difficulty urinating, ataxia and the inability to rise. Nursing care and intensive therapy may pull a horse through, but many die or are euthanized.

Prevention is difficult, as there is no known vaccine for the neurologic form of herpes. There may be some protection from the respiratory form from the vaccine that we use, but the jury is still out on this. The most effective prevention is strict quarantine from infected horses. This has worked well in outbreaks to prevent further spread, but this virus can be carried on handler’s hands, tack, rub rags, equipment, vans etc. Any common watering buckets and troughs should be eliminated. Persons handling outside or multiple horses should wear rubber exam gloves and change between horses.

There are a number of restrictions on the movement of horses in the Mid-Atlantic at this time, and anyone competing, racing, or going to any breeding farm in this area should check with the event or farm for their requirements. A negative PCR test for herpes on blood and nasal swabs is currently the best way to identify any silent carriers and this test is currently required by many establishments. Call the clinic if you have questions and speak with one of our doctors.

FESCUE TOXICITY

This is the time of year when fescue toxicity becomes an issue, as mares grazing on endophyte infected fescue have many problems foaling and producing milk. Almost all of our fescue in Central Virginia is infected. The best preventative is to remove all pregnant mares from pasture the last 60 days of gestation and feed only non fescue hay along with their regular grain ration.

Mares on pasture that are not starting to develop an udder within 3 weeks of their due date should start on domperidone to counteract the effects of fescue. This is often successful in preventing weak foals, thickened placentas and poor milk production.

SPRING VACCINATIONS

Many of you annually update your horse’s vaccinations in the spring and some may have already received reminder cards in the mail to schedule these. The important vaccines that must have boosters in the spring are West Nile virus, eastern and western encephalomyelitis, and Potomac fever. Your horse’s schedule may require influenza, tetanus, rhinopneumonitis, botulism, or rabies. Call the clinic to discuss your animal’s needs and to schedule the vaccines.

FOALING SEASON

It’s the time of the year when we see a significant number of new foals and pregnant mares.  Hopefully, all will progress in a normal fashion, but it is important to watch for some signs that the pregnancy is not entirely normal.  Some of the problems associated with an abnormal pregnancy may be relatively obvious to the horse owner.

We frequently are called out to examine a mare when she begins producing milk prematurely or is producing a vaginal discharge.  These signs may result from a primary problem with the fetus or from a primary problem with the placenta.  In cases like these, abdominal ultrasonography can be used to assess fetal well-being.  The two most important issues we examine with the ultrasound include the combined thickness of the uterus and placenta (CTUP) which generally is less than 1 cm in thickness during the last trimester of pregnancy and the fetal heart rate (FHR) which generally is greater than 80 and less than 140 beats per minute.  Fetal heart rates that fall outside of the normal range indicate severe fetal distress.  If the CTUP is within normal limits, the fetal distress is likely the result of fetal infection.  When the CTUP is greater than normal, it is indicative of placental infection (placentitis).  The lack of proper placental function (providing oxygen to the fetus and filtering fetal blood) will result in fetal stress.  In some cases of placentitis a bacterial culture of the external portion of the mare’s cervix may help direct us as to the appropriate antibiotic regime to chose.  In any of these cases, there are several medications we will use in combination to attempt to prevent premature delivery.  Not all outcomes are successful, but we in fact have several normal foals born to mares with pregnancy problems every year.

Sometimes a mare may appear to be too large for her stage of gestation (normal gestation is 333 days +/- 30 days).  If the mare appears extremely large earlier in her pregnancy that you would anticipate – consider that she may be caring twins or have a condition known as “hydrops” where there is an abnormal accumulation of fluid within the placenta or within the amniotic cavity.  These cases are generally diagnosed with the combination of palpation per rectum and abdominal ultrasonography. Medical management of either of these problems typically does not result in a viable foal, but all efforts are directed toward maintaining the health of the mare.   Hopefully, you all will have mares with uneventful pregnancies – and we will only see you for a new-born examination.

NEW GAMMA CAMERA

BREC has installed a new state of the art gamma camera and softwear to update our nuclear scintigraphy unit. This will enable us to better diagnose active bony conditions of the skeleton and add support for our lameness workups. Dr. Steve Trostle is in charge of this new camera and he, Mandy Walton and Tina McPheeters, our technicians who run the camera, are very excited about their new capabilities.

WELCOME

We are happy to announce that Dr. Tracy Norman is coming back to the Blue Ridge Equine Clinic as an internal medicine specialist.  As you may recall, Tracy was an intern here in 2002.  Since that time she has been an internal medicine resident at the Texas A&M Veterinary Teaching Hospital in College Station, Texas.  There is a tremendous case load at the hospital, as Texas has more horses than any state in the country.  After growing up in Chester County, Tracy obtained her Bachelor’s degree from Washington and Lee University, earned her Master’s degree from Villanova University and graduated from the University of Pennsylvania School of Veterinary Medicine.  Please stop in and welcome Tracy “back into the fold.”

PLAUDITS TO CLIENTS

Congratulations to our clients who have had major successes over the winter. Rachel Spencer’s Popeye K was The Chronicle of the Horses’ HUNTER OF THE YEAR for 2005 and he continues to win in Florida this winter. Felix Nuesch was elected to the VHSA Hall of Fame at their meeting in Hot Springs in December. Eldon Farm’s three year old filly Dyna’s Destiny has now had two stakes wins in her last two starts and promises much more for the spring. Many more of you are competing and winning – lets us know about it. We love being part of your team.