Bandalero Ranch Blog

Veterinarian Blast - What is Coggins and Why do we test?

By Bandalero Ranch
Sep 14, 2012

Every day we submit blood samples to our laboratories for horses that are obtaining health certificates in order to attend shows or sales.  What is a ‘Coggins’ test.  Why do we do it?

The test is looking for the reaction of the body to the virus that causes Equine Infectious Anemia,

The Coggins test is the named after the veterinarian, Dr Leroy Coggins, that created the special test that identifies the immune response, or antibodies to the Equine Infectious Anemia Virus (EIAV).

EIA affects all species of equine, horses, donkeys, mules, zebras and ponies.  The disease is distributed around the world. It was first described and identified in France in 1843.  In the US only about 20% of all horses are routinely tested.  Our prevalence is basically unknown. 

 

 

Our most recent national outbreak occurred in Arkansas last year affecting 40 horses from one facility.  The incidence is highest in those states with a larger population of horse flies and deerflies. 

Infection with the EIA Virus results in recurrent episodes of cyclic fevers, lethargy, ventral edema, unexplained weight loss, anemia, bruises on the gums and other mucosa, and occasionally death.  Most horses have an immune response which will gradually control the disease within a year, and then will no longer show any sign of the disease.  Unfortunately these horses will be carriers of the virus for life. 

Notice machete like mouth parts

They may appear normal, but serve as a reservoir of infection for uninfected horses through the bites of flies, or other biological vectors.

Diagnosis is based primarily on serological testing.  There is no treatment. The US prohibits interstate travel of infected animals, and has attempted to prevent the spread of the disease by requiring every horse that crosses any state line to be negative.  States are variable in their requirements.  Some states ask that the horse have a negative test within 12 months, others within 6 months.

There are essentially three stage of the disease process.  The acute phase begins approximately 4 weeks post exposure.  The chronic phase lasts approximately one year, and the carrier or persistent phase endures for the rest of the horse’s lifespan.

The symptoms are variable and depend on the stage of the disease.  Acutely, the horse has a high fever, lethargy, ventral edema, and bleeding from the nose.  The acute stage is usually less than a week, and frequently goes completely unnoticed.

The chronic part of the disease results in repeated bouts of the above symptoms, gradually reducing in severity. Weight loss may be observed as the horse struggles to maintain normal blood values. After one year, the horse will usually no longer have any symptoms at all.  Most horses appear completely normal.

EIA is caused by a virus that is very closely related to HIV.  The body may learn to adjust to it, but it never can completely clear it. The virus cannot affect people or any other animals other than members of the equine family. Any sort blood to blood transmission can pass the virus. 

Horse Fly

Biting flies, sexual intercourse, or reused needles  and surgical instruments can all pass the virus.

There is no specific treatment other than supportive for EIA.  Because EIA is a reportable disease in the United States, positive horses may only be isolated from all other horses, euthanized, or transported to a recognized research facility.  If the horse is not euthanized, they are branded on the jaw with a specific two digit state code followed by the letter A, then a second two digit number specifying that specific horse .

The virus is not long lived outside of the horse’s body, and the contamination area is considered to be 200 yards (assuming this is accounting for the distance of the fly’s flight path)

Preventive vaccines are not yet available, and it is because of our governmental strict surveillance that this disease has been controlled in our country.  Outbreaks can and do still occur.  Testing should occur as a normal yearly check up, and before admitting any new horse to any facility.  Horses should never be injected with previously used needles, and fly control should be rigorously applied.

Dr. B.K. Thwaits Questions? Comments?

Placenta Evaluation

By Bandalero Ranch
Apr 23, 2012

By Patrick M. McCue, DVM, PhD, Diplomate American College of Theriogenologists The placenta is the connection between the developing fetus and the mare and provides the means for obtaining nutrition and for gas exchange.  Examination of the placenta can offer valuable insight into the health of the newborn foal. Consequently, it is recommended that owners, farm managers or foaling attendants perform an evaluation of each placenta.

The placenta is normally passed within three hours after foaling.  Once passed, the placenta should be immediately removed from the foaling area and rinsed free of gross debris.  Disposable plastic or latex gloves should be worn during handling and examination.  If possible, the weight of the placenta should be determined.  An inexpensive bathroom scale is sufficient.  Under normal circumstances, the weight of the placenta will be approximately 11 % of the body weight of the foal. An increased weight may be the result of edema associated with factors such as fescue toxicosis or may be due to aninfectious condition such as placentitis.  Both conditions may be associated with a medically compromised fetus.

The placenta consists of three primary components, the outer placental membrane or chorioallantois, the inner placental membrane or amnion, and the umbilical cord.  In a normal foaling, the thicker outer placental membrane is almost always turned inside-out as the placenta is passed.

For examination, the outer placental membrane should be turned right-side out and then spread out on a clean flat surface. The allantoic (side toward the foal) surface is smooth and pink and blood vessels are visible coursing along its surface.  The chorionic (side toward the uterus) surface has a brick-red velvety appearance due to the presence of structures known as microcotyledons.  Microcotyledons are the microscopic villi or finger-like projections that provide the ‘Velcro-like’ attachment of the placenta to the uterine lining.

The membranes may be laid out with the chorioallantois in an “F” or “Y” shape, with the two horns of the placenta forming the arms of the “F” or “Y” and the body of the placenta forming the base.  The umbilical cord and amnion should protrude from the base or body of the placenta.

One of the first things that may be noted is that the tips of the placental horns differ significantly in size and thickness.  The larger horn housed the fetus and is referred to as the pregnant horn.  The tip of the pregnant horn is always thicker than the tip of the smaller (non-pregnant horn).

The placenta should be examined to determine if it was passed intact or if a piece is missing and potentially still inside the mare.  By far the most likely portion of the placenta that may be retained is the thin tip of the nonpregnant horn.  Retention of even a small piece of placenta in the uterus poses a very serious threat to the health of the mare.

The area of the body of the placenta that was in direct contact with the cervix of the mare will be pale in color and devoid of the red velvety microcotyledons.  This area is referred to as the ‘cervical star’ region of the chorionic surface of the placenta.  Ascending bacterial infections that pass through the cervix may result in thickening or the presence of a mucus-like exudate in the area around the cervical star.  If a placental infection is present, the foal may have been exposed to pathogenic micro-organisms prior to being born and should be considered high-risk for medical complications.

The thin, white amnion should be examined next.  The primary abnormality that may be noted in the amnion is a yellow-orange discoloration due to meconium staining.  Stress to the fetus prior to birth may result in premature passage of fecal material (meconium).  Meconium staining may be an early warning sign that the foal is compromised.  In addition, affected foals may aspirate meconium into their lungs and develop serious respiratory complications.

The umbilical cord will virtually always have a mild to moderate degree of twisting present.  Excessive twisting of the cord can result in decreased blood flow from the placenta to the fetus and other problems.

Evaluation of the placenta is a valuable procedure that can positively impact the health and welfare of both the newborn foal and the mare.  It is recommended that your veterinarian be contacted for an initial lesson in field evaluation of the placenta and that he or she be notified if abnormalities are identified in subsequent placental examinations.

The New Bandalero Ranch Blog Is Here!

By Bandalero Ranch
Apr 23, 2012

Welcome to the Bandalero Ranch Blog. Here you will find information about our facilities, quarter horses, shows, competitions, breeding information and sales promotions. We look forward to sharing information with you.