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Cyndi Kasper, DVM


View a document produced by the AAEP that describes the value of a regular dental checkup for your horse.

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HERDA - Hereditary Regional Dermal Asthenia
The Many Faces of Rhinopneumonitis




Learn To Recognize Your Horse's Dental Problems
(reprinted with permission from the April 2008 Horse Health Articles of the AAEP)

Horses with dental problems may show obvious signs, such as pain or irritation, or they may show no noticeable signs at all. This is because some horses simply adapt to their discomfort. For this reason, regular dental examinations, at least annually, are essential to your horse’s health.

It is important to catch dental problems early. If a horse starts behaving abnormally, dental problems should be considered as a potential cause. Waiting too long may increase the difficulty of remedying certain conditions or may even make remedy impossible. According to the American Association of Equine Practitioners (AAEP), the following indicators of dental problems will help you know when to seek veterinary attention for your horse:

  1. Loss of feed from mouth while eating, difficulty with chewing, or excessive salivation.
  2. Loss of body condition.
  3. Large or undigested feed particles (long stems or whole grain) in manure.
  4. Head tilting or tossing, bit chewing, tongue lolling, fighting the bit or resisting bridling.
  5. Por performance, such as lugging on the bridle, failing to turn or stop, even bucking.
  6. Fould odour from mouth or nostrils, or traces of blood from the mouth.
  7. Nasal discharge or swelling of the face, jaw or mouth tissues.


Oral exams should be an essential part of an annual physical examination by a veterinarian. Every dental exam provides the opportunity to perform routine preventative dental maintenance. Mature horses should get a thorough dental exam at least once a year, and horses 2 – 5 years old should be examined twice yearly.

For more information about proper dental care, ask your equine veterinarian for “Dental Care: The Importance of Maintaining the Health of Your Horse’s Mouth,” a brochure provided by the AAEP in conjunction with Educational Partner Bayer Healthcare – Animal Health Division. Additional information is available on the AAEP’s Web site at www.aaep.org/horseowner.

The American Association of Equine Practitioners, headquartered in Lexington, Ky., was founded in 1954 as a non-profit organization dedicated to the health and welfare of the horse. Currently, the AAEP reaches more than 5 million horse owners through its over 9,000 members worldwide and is actively involved in ethics issues, practice management, research and continuing education in the equine veterinary profession and horse industry.



HERDA - Hereditary Regional Dermal Asthenia
Dr. Cyndi Kasper BSc, DMV

What Is It?: Hereditary equine regional dermal asthenia (HERDA) is an inherited connective tissue disease in Quarter Horses – it is an autosomal recessive trait most likely passed on from Poco Bueno. It is characterized by abnormal skin along the back that tears easily and heals into disfiguring scars. Symptoms typically don’t appear until the horse is subjected to pressure or injury on his back, neck or hips. In most cases, the skin has an unusual feeling but appears normal until external pressure is applied.



When Is It Diagnosed?: HERDA typically surfaces when the horse is around two years old. This is the typical time when horses go into training. The saddle literally tears the skin off their backs – the saddle presses down and shifts on an affected horse; it causes the outer skin along the back to rub on the underlying layers. Younger horses are typically diagnosed with HERDA after suffering an injury that scrapes, punctures or tears the affected skin. These wounds cannot be sewn together. The healing is dramatically impaired and heals with awful disfiguration. Even an act of rolling can tear the skin.

How Does It Happen?: The horse’s skin is the largest organ of the body. It is a multi-layered protective covering. The three layers include the outer epidermis, the middle dermis, and the deep sub cutis. Connective tissues bind the three skin layers together. Collagen is the most abundant protein in the body and when it attaches to elastin, the combination forms a strong connective tissue. In HERDA, the breakdown occurs in the dermis layer. Collagen cells are damaged and disorganized. This weak bond cannot stand normal external stresses, so the layers separate and the epidermis rubs against the sub cutis. Often the only connection between the layers is made by small blood vessels. This disease is mostly found over the thick skin of the neck, back and hips. Only in some cases have the lower limbs been involved and there usually no problems around the cinch area.

It is noted that all the affected horses are related to each other and that they all have in-breeding loops. In other words, it follows the pattern of being a recessive trait. The only way to contract the disease is if both parents are carriers of the gene or if one parent is a carrier and the other is an affected horse. A recessive disease remains silent in these heterozygous carrier horses; only the double recessive genes will outwardly show the signs of HERDA. This is why HERDA has been carried forward by successive generations without showing these signs. Now, their great grand offspring are being bred to each other and there’s just a higher incidence.



Why Is It Appearing Now?: Some of the HERDA affected horses have been by top sires and out of the industry’s best mares. The number of disease animals documented is still relatively small. With concentration of bloodlines in certain disciplines, the HERDA gene has been quietly passed on from one generation to the next. And genetic protocols such as embryo transfer enable humans to successfully propagate several offspring from a couple of breedings. As HERDA carriers are allowed to reproduce, reproduce and reproduce again, they pass on HERDA genetics to new generations. As those second-generation horses perform and win, they’ll be bred back to the best of the best, which are most likely relatives. Because this has been happening since 1970…we are quietly producing more…





The Many Faces of Rhinopneumonitis
Dr. Cyndi Kasper BSc, DMV

What Is It?: It is an equine respiratory disease associated with infection of the upper airway epithelium by equine herpesvirus type 1 or type 4.The greatest burden of infection is in foals during their first year of life between 4 and 12 months and is commonly called the "foal snots". In 2 and 3 year old in training or on the racing circuit, outbreaks are common. Horses older than three can continue to show evidence of periodic re-infection throughout their lifetime with only minimal clinical signs - these horses can pass on serious sequelae. These clinical sequelae include abortion, neurological disorders, neonatal foal death, ocular disease or death.

How does it Spread?: Widespread outbreaks of herpesvirus respiratory disease may occur, and infection spreads rapidly within susceptible horse populations. Natural transmission is readily accomplished by contact with another infected horse, its aerosolized respiratory secretions, or virus-infected fomites such as manure.From exposure to clinical signs is about 2-5 days; however, they can shed the virus for up to fourteen days.

What Does it Look Like?: The most common clinical sign is nasal discharge. In early stages, the discharge is watery, free-trickling and frequently goes unnoticed by attending personnel. This clear nasal discharge is loaded with infectious virus. By the second or third day, this discharge changes to a thicker, white-coloured mucous. Other clinical signs that may be present include: fever, enlarged lymph nodes, conjunctivitis with a mild discharge, decreased energy and anorexia. Occasionally, lower respiratory disease, such as pneumonia, may follow.

What Can It Do To My Broodmare?: Even in the absence of signs of respiratory disease, rhinopneumonitis carries the risk for significant sequelae such as abortions. Late term abortion resulting from viral spread to the fetus that follows respiratory infection of pregnant mares has been recognized for many years. The respiratory infection that usually precedes abortions is often asymptomatic. Fetuses can be affected in late term and can be born alive; however, they are weak, fail to nurse, become lethargic and show severe respiratory distress. Deterioration occurs rapidly despite medical intervention.

How Is It Treated?: The goals of therapy include: to improve clinical signs, to improve hydration and minimize complications arising from the effects of bacterial superinfection or systemic spread of viral infection.

How Can It Be Prevented?: Disease prevention, rather than treatment or attempts at eradication offers the most effective means for controlling herpesvirus and its sequelae. Strategies include prophyllactic immunization and preventative herd-management practices. Foals become susceptible to infection at five to six months of age. Vaccinations and subsequent boosters should be implemented to provide maximal protection in preparation for the stresses associated with weaning, transport, relocation, training and performance events. A reasonable course is two IM doses spaced at three-week intervals just prior to weaning, with single booster doses every three to six months depending upon the level of risk. Pregnant mares should be immunized at 5, 7 and 9 months of gestation (+/- at 3 months dependent on risk). Vaccination does not prevent infection, but diminishes the intensity of clinical signs and magnitude and duration of shedding of infectious virus.
Management recommendations are based on the practice of segregation of the horses on the premises into small groups, to maintain each group as an isolated unit and reduce stress. The greatest danger for herpesvirus infection lies in the introduction of new horses into established groups (ie: Racehorses into Broodmare bands). The addition of any new horse into a closed group should be preceded by a 21 day period of isolation and should be monitored for signs of infection.

Remember... just one shedding horse can instill grave complications on even small herds.