Equine Information
Angular Limb Deformaties
Monday, February 27, 2012
As we enter into foaling season we will be faced with foals with Angular limb deformities (ALD or “crooked legs”). Please use the following as a review of ALD, their causes, and potential treatments.
ALD may occur from various factors such as exercise, nutrition, infection, and abnormal weight bearing or be due to a congenital/inherited defect. The deformities develop over time from unequal growth across the growth plate (or “physis” see figure 1). There are nonsurgical and surgical options to correct these deformities.
The terms used to describe the direction of the deformity are valgus (“knock kneed”) or varus (“bow legged”). These terms refers to the angle created by the bone above and the bone below the joint in question (figure 2). The most common types of ALD are carpal varus (“knock kneed”) seen in yearlings followed by fetlock varus (“pigeon toe”) and tarsus valgus (“cow/sickle hock”) seen in weanlings. In addition to angular limb deformation, a rotational deviation of the limb can occur at the same time. A rotational deformity means that all of the angles of the bones are in lijne but the entire limb rotates inward or outward at the elbow and shoulder. It is most common to see outward rotation with valgus deformities and inward rotation with varus deformities.
Evaluation of foals born premature, dysmature, or those with ALD present at birth should be completed by your veterinarian within the first 24 hours of life. Evaluation should include both subjective visual assessment while standing and walking, and objective radiographic assessment if warranted.
Treatment options include non-surgical and surgical management. Any option has to be balanced with the age of the foal and the remaining growth potential for the affected bones. Minimal growth occurs in the growth plate of the cannon bone growth plate after 3-4 months of age. Minimal growth occurs in the growth plate of the radius (Figure 1) after 16 - 18 months. If non-surgical methods are not successful in correcting the ALD, surgical options need to be initiated while growth potential remains in the growth plate. This means that surgical options need to be started by 3 months in the fetlocks and 14 months in the knee.
Non-surgical Options:
1. Stall rest: Effective in newborn foals with incomplete ossification. Stall rest prevents crushing of the carpal and tarsal bones.
2. Hoof Manipulation: Frequent corrective trimming, with or without medial or lateral extensions, can be an effective way to manage mild ALD.
Surgical Options:
Surgical correction should be used early in foals with moderate to severe conditions, or in yearlings that were treated unsuccessfully with conservative management. Surgical treatments recommended from your veterinarian are based on the type and severity of the deviation. Treatment recommendations include:
1. Growth acceleration: Periosteal transection and elevation (“periosteal stripping”)
2. Growth retardation: Transphyseal screw placement (single screw – Figure 3) or transphyseal bridging (“screw and wires” – Figure 4)
Overall Angular limb deformities are a serious but treatable ailment in the growing horse. Multiple treatment options exist and consultation with your veterinarian should be done early and frequently during the growth of your foal.
Reference: Auer JA: Angular Limb Deformities. In: Equine Surgery, 4th edn, Eds JA Auer and JA Stick. Saunders Elsevier, St. Louis. 2012: pp. 1207-1220.
Figure 1: The red arrow identifies the growth plate (physis). This structure is responsible for the bone growing longer.
Figure 2: The left diagram demonstrates a horse with a valgus ALD and the right diagram demonstrates a horse with a varus ALD
Figure 3: Transphyseal screw placement using a single screw that crosses the growth plate to correct an ALD in the hock (left) or the fetlock (right). This procedure prevents growth on the left side while the right side grows unimpeded.
Figure 4: "Screws and wires" placed using 2 cortex screws and a steel wire. This procedure prevents growth on the left side while the right side continues to grow unimpeded.
Marshall Stevens, DVM
John G. Peloso, DVM
Vaccinations From Foals to Yearlings
Friday, February 3, 2
Immunization is a vital step in the protection of your horse from potentially debilitating or fatal infectious diseases. A good immunization program is essential to keeping your horses healthy. Vaccination provides a biological protective barrier between your horse and several infectious diseases. Vaccination dramatically reduces the risk of your horse getting infected, however it does not prevent disease in all circumstances. Vaccines are a preventative measure and should be administered before likely exposure rather than in the face of exposure. It should also be noted that not all horses in a herd will be protected to an equal degree or for an equal duration following vaccination.
Generally it takes 1-2 weeks after a full series of vaccinations are completed until your horse is fully protected. Following vaccination protective antibodies in the blood and other specialized immune system components guard against the invasion of specific diseases. These antibodies decline overtime. Therefore we use booster vaccines at regular intervals to maintain adequate protection. The booster interval varies depending on the disease, and exposure risk. Some diseases such as tetanus and rabies only require a once yearly booster to achieve protection. Other diseases such as Eastern and Western Equine Encephalitis (sleeping sickness) and West Nile Virus require more frequent booster intervals particularly for horses residing in endemic areas such as Florida.
Foals are generally not vaccinated before weaning as they derive their protection from maternal antibodies they receive via the colostrum. That is why it is critically important they receive adequate colostrum in the first hours after birth.
The specific immunizations required by a particular horse or horses depends upon several factors: age, use, breed, sex, general management, exposure risk and geographic location. Before implementing a vaccination policy you should consult with your veterinarian to design a protocol approriate to your horse’s individual needs.
In general we divide the various vaccines into two groups: Core vaccinations and non-core or risk-based vaccinations
The American Veterinary Medicine Association defines core vaccinations as those “that protect from diseases that are endemic to a region, those with potential public health significance, required by law, virulent/highly infectious, and/or those posing a risk of severe disease. Core vaccines have clearly demonstrated efficacy and safety, and thus exhibit a high enough level of patient benefit and low enough level of risk to justify their use in the majority of patients.” The following vaccinations are recommended for every horse in Florida. These diseases are endemic to the state and pose a serious risk.
· Tetanus
· Eastern Equine Encephalitis (EEE) and Western Equine Encephalitis (WEE)
· West Nile virus (WNV)
· Rabies
Non-core / Risk-based vaccinations are included in a vaccination program after the performance of a risk-benefit analysis. The use of risk-based vaccinations may vary regionally, from population to population within an area, or between individual horses within a given population. If unsure of the infectious diseases endemic to your area or if your horse is travelling to a new area, you should consult with your veterinarian to ensure your horses are adequately protected. The following equine vaccines are classified as risk-based:
· Equine Influenza (Flu)
· Equine Herpesvirus/Rhinopneumonitis
· Strangles (Streptococcus equi)
· Anthrax
· Botulism
· Equine Viral Arteritis
· Potomac Horse Fever
· Rotaviral Diarrhea
The following is our recommended vaccination protocol from foal to yearling:
EEE, WEE, Tetanus, WNV
· 3, 4, and 5 months old and then December
· Booster every 6 months
· EEE, WEE, WNV booster should take place in spring every year before peak mosquito season
· Any horse that sustains a wound should receive a tetanus booster unless vaccinated for tetanus in the last 2 months
Rabies
· 6 and 7 months old and then January
· Booster annually
Equine Influenza
· Recommended for all horses on breeding farms, attending sales or shows, and in training barns
· 6 months old, then booster every 6 months
· Also recommended 30 days prior to sales/shows/shipping
Equine Herpesvirus / Rhinopneumonitis
· Recommended for all horses on breeding farms, attending sales or shows, and in training barns
· 5 and 6 months old, and December
· Also recommended 30 days prior to sales/shows/shipping
· Booster every 6 months
Strangles
· Only indicated for horses on farms where disease is endemic
· Intranasal or intramuscular vaccination when over 6 months old, booster 1 month later, and again in December
· Booster annually
Damian McEntee, DVM
Foal Diarrhea
Friday, January 27, 2012
Causes of Diarrhea in Foals
Foal heat diarrhea: This is a mild form of diarrhea that occurs in foals between 5 and 14 days of age, around the time the mare has her “foal heat”. This type of diarrhea is generally self-limiting and does not require treatment.
Viral diarrhea: Rotavirus is the most common cause of viral diarrhea in foals. The disease may be mild or foals may have profuse, watery diarrhea; leading to dehydration, depression and anorexia. Currently, a vaccine against rotavirus is commercially available and is administered to pregnant mares. The response of foals to the dam’s vaccination is variable; the vaccine may only decrease the severity of the diarrhea or it may completely prevent the disease in foals. Rotavirus is associated with gastric ulceration; therefore, antiulcer medications are important in the treatment of rotavirus.
Bacterial diarrhea: Many types of bacteria cause diarrhea in foals and infection will result in a wide range of clinical signs.
Clostridium spp.: Clostridial organisms produce and release toxins in the intestinal tract that may cause severe damage to the lining of the large intestine. The resulting diarrhea is frequently profuse, watery and may be bloody. These organisms can cause diarrhea in horses of any age, and foals with this disease frequently exhibit signs of colic and dehydration.
Salmonella spp.: This organism may cause diarrhea in horses of any age, but it is frequently associated with septicemia (blood infection) in newborn foals. The diarrhea caused by this organism is frequently severe and life threatening in foals. Foals with Salmonellosis often have a high fever and signs of abdominal pain. It is important to remember that this organism is contagious to other horses and humans.
Rhodococcus equi: This organism typically causes severe pneumonia in foals, but infection of the lymphoid tissue in the intestinal tract may result in the production of diarrhea. A foal with R. equi diarrhea is generally 1-4 months of age and will frequently have some degree of pneumonia, concurrently.
Lawsonia intracellularis: This disease is usually seen in older foals, weanlings and yearlings. Infection will result in severe protein loss which will lead to depression, weight loss and edema formation, in addition to diarrhea.
Protozoal diarrhea: Cryptosporidium is a protozoal pathogen that generally causes self-limiting diarrhea in foals, unless their immune system is already weakened by a concurrent disease.
Diagnosis
The majority of the time, the cause of foal diarrhea can be identified by laboratory analyses and /or bacterial culture of the feces.
Treatment of diarrhea in foals
In the majority of cases of foal diarrhea, accurate diagnosis and early treatment willhelp lessen the severity of disease. Obtaining an accurate diagnosis for the cause of the diarrhea is important as the appropriate medication plan can then be formulated. Foals with diarrhea frequently become dehydrated and require intravenous fluid therapy. Nursing care is an important aspect of the treatment of foals with diarrhea – they need to be kept clean, dry and warm.
Isolation
As many causes of diarrhea are contagious to other horses and humans, foals with diarrhea should be kept in isolation. The use of gloves, boots and a foot bath outside the stall are helpful in preventing the disease from spreading to other horses on the farm. Please don’t forget that many of these organisms also have the potential to cause disease in humans; therefore, wearing gloves and frequent hand washing are very important when handling foals with diarrhea.
Lauren Danskin, DVM
J. Barry David, DVM, Diplomate ACVM
Fetal Malposture and Dystocia
Tuesday, January 24, 2012
A normal delivery progresses in three stages. When growing in the mare, the foal grows like they are sleeping on their back with their hind legs pointing forward towards the mares head (Figure 1). During the first stage of labor, the foal repositions its body and legs in the womb so that it looks like it is “jumping out” of the mare with the abdomen down and both front limbs and head pointing towards the mare’s tail (Figure 2). The first stage of labor lasts about 30 minutes to 6 hours. The mare becomes restless, starts to pace around the stall, and shows variable degrees of discomfort that can resemble colic. This is a sign that the contractions have begun. The second stage of labor is the actual delivery of the foal, and it begins when the placental membrane ruptures and the allantoic fluid rushes out (“breaking water”). After the mare breaks water, the fetus is usually delivered within 30 minutes. The third stage of delivery happens after the foaling, and it ends when the mare passes the placenta. The placenta should be expelled within 3 hours, post-delivery.
During the first stage of foaling, the foal should reposition himself in the uterus with the belly down, both front limbs and head extended forward into the birth canal, and the hind limbs extended back. This allows the long extremities of the foal to be delivered through the birth canal without getting caught in the pelvis. If you don’t see TWO FEET and the HEAD come out first, SOMETHING IS NOT RIGHT! This could be a sign that the foal is not properly oriented within the birth canal and may lead to a dystocia.
By definition, dystocia is difficulty in giving birth, or inability to give birth unaided. If the mare continues to strain, she gets up and down and you don’t see both of the foal’s feet come out first, or the delivery is taking longer than 30 minutes after the start of stage 2, then there is a problem. The most common cause of dystocia is fetal malposture, which means that the foal’s limbs and/or head are in abnormal positions (see Figures 3 – 5 for example). Fortunately, veterinarians and experienced broodmare managers can generally correct simple cases of dystocia on the farm. However, if the dystocia is not easily corrected, the mare may need to be referred to a veterinary hospital. At a referral hospital, the mare can be placed under general anesthesia and have her hind end raised into the air using a hoist. This allows the veterinarian to reposition the foal in the uterus (where there is more room vs. the pelvis) and does not have to deal with the forceful contractions of the mares uterus. Also, a C-section can be performed if the orientation of the foal cannot be corrected for a vaginal delivery (e.g. breech position = foal’s hips present first. See figure 6).
If you suspect that your mare is having a dystocia, you need to call your veterinarian immediately. While you are waiting for your veterinarian to arrive, keep your mare calm and standing or walking to prevent her from straining excessively. Start to prepare the mare for delivery by wrapping the tail, and cleaning the perineal area with warm water and mild soap. It is also important to get the trailer ready in case you need to take the mare to a referral hospital.
The greatest chance for a positive outcome is to recognize a problem quickly and seek immediate medical attention for the mare.
S. James Fukuda, DVM
Figure 1: The position of the growing foal.
Figure 2: This foal is rotating into position in preparation for delivery.
Figure 3: One limb is extended backwards.
Figure 4: One limb is over the head.
Figure 5: Both hind limbs flexed forward - "Dog Sitting" position.
Figure 6: Foals hips are in the birth canal with the hind limbs extended forward - "Breech"
Foaling Tips
Monday, January 16, 2012
Getting Ready
Vaccines: Your veterinarian will advise you as to what vaccines are appropriate for your mare. Most pre-foaling shots are administered at 10 months gestation. Herpesvirus vaccines are given as a series at 5, 7 and 9 months gestation whereas rotavirus vaccines are given at 8, 9 and 10 months gestation.
Predicting Foaling: Predicting when a mare will foal is tricky. Signs that indicate your mare is close include: bagging up, waxing, and an increase in the amount of calcium in the mare's milk. Stall side tests are available to check your mare's milk- if the test is negative, you can be pretty confident that your mare will not foal in the next 48 hours. A foal alert device may also be used. Foal alerts are typically sutured into the mare's vulva prior to foaling. When delivery begins, the magnet on the device separates and a recorded call is made to the programmed numbers.
Foaling Area: When your mare is close to foaling, you will need to choose a safe area for her to foal. In cold or damp weather it is best your mare foal inside, as neonatal foals are very susceptible to hypothermia. A large stall with deep straw bedding makes an ideal foaling area, especially if the stall can be monitored from a distance.
The 3 Stages of Foaling
Stage 1 - This is generally the longest stage, lasting 1-4 hours. The mare will often act restless, circling and lying down frequently. Some mares will look colicky, showing signs of abdominal discomfort, like looking at their flanks and sweating. Typically, the best assistance you provide during this state is patience as mares rarely require help.
Stage 2 - This stage begins when the mare's "water" breaks and ends when the foal has been delivered. It should take 15-20 minutes. The water breaking is actually the rupture of the chorioallantoic membrane releasing allantoic fluid. Most mares lie down at this point. The foal should “deliver” showing 2 feet followed by the muzzle and the sole of the foals feet should point in the same direction as the sole of the mares feet. The foal is encased in the thin, transparent amniotic sac. This sac may be torn away from the foal's nostrils if it does not do so during delivery.
If a velvety red sac is “delivered” it is called a "red bag delivery" and it is a true emergency. This sac needs to be cut immediately so the foal can breathe; do not wait for your veterinarian. Discussing this situation with your veterinarian in advance will ensure you are better prepared to face this emergency.
Stage 3 - The final stage of labor is passing of the placenta. It should pass within 1-3 hours after the foal is delivered. It is considered retained if it has not passed after 3 hours and you should contact your veterinarian.
When To Call Your Vet
1. A red bag delivery;
2. Stage 2 lasting longer than 45 minutes;
3. Incorrect “delivery” of the foal. For example, a leg back or head back will always require veterinary intervention;
4. Foal fails to stand or nurse by 2 hrs;
5. Mare fails to pass placenta by 3 hours;
6. Post foaling signs of colic (mare or foal)
Foaling Kit
1. Bucket with mild soap and warm water to rinse the mare’s udder prior to foaling
2. Vetwrap to wrap mare's tail
3. Flashlight with extra batteries, as most mares foal at night or during early morning hours
4. Dilute chlorhexidine solution for umbilical dip
5. Umbilical tape to tie the umbilical cord if it does not break
6. Scissors to cut string or to cut the placenta in the case of a red bag delivery
7. String to tie up the mare's placenta should it not pass immediately after foaling
8. Towels
9. A plastic bag to save the placenta for your veterinarian to evaluate.
10. Clean container to nurse mare into should your foal fail to nurse
11. Frozen colostrum
12. An enema in case your foal does not pass meconium
Sarah Shaw, DVM
Preparing Your Mare for the Breeding Season
Tuesday, January 3, 2012
A successful breeding program depends largely on your organization and pre-breeding season preparation. Farm management, preventative veterinary medical care and animal husbandry all go hand-in-hand toward producing high pregnancy and foaling rates.
Breeding Soundness Exam: Before you go to the expense and effort of getting your mares bred, they should be examined prior to the breeding season to evaluate the health of their reproductive tracts. This includes assessment of the mare’s general health via physical exam, examination of the mare’s vulvar conformation, palpation of the uterus per rectum and a visual (speculum) examination of the vagina and cervix. In addition, samples that should be obtained and sent to a laboratory include a swab for microscopic analysis and bacterial culture and a biopsy to examine the microscopic architecture of the lining (endometrium) of the uterus. These procedures will allow you to identify problems that may require treatment or identify mares that may have fertility issues.
The external area around the vulva is known as the perineum. Poor conformation (tipped vulva) of the perineal region will lead to fecal contamination of the reproductive tract and may result in infertility or early abortion. A Caslick’s procedure is a minor surgical procedure that involves suturing the upper portion of the vulva and is an effective means to prevent uterine infection. Manual and speculum examination of the vagina and cervix is important and may identify other potential problems such as urine pooling or cervical tears, which will require surgical correction prior to the breeding season. Palpation of the reproductive tract and ultrasound examination of the uterus and ovaries is performed to identify abnormalities such as uterine cysts, the accumulation of uterine fluid or ovarian cysts, all of which required therapy and may limit fertility.
Uterine culture involves using sterile technique to retrieve a small sample of uterine secretions in order to identify harmful bacteria and/or fungi inhabiting the uterine lining. If a uterine culture is positive, laboratory personnel will then perform tests to determine which drugs will be effective in treating the infection (a sensitivity report). Uterine cytology samples are generally taken simultaneously with the culture. These samples are smeared onto a microscope slide, stained and analyzed for evidence of infection and / or inflammation. Uterine cytology offers a quick, in-house prediction of uterine infection status, while the culture is incubating. Uterine biopsy is considered the “gold standard” for determining the health status of the equine uterus. A biopsy involves the removal and analysis of a small section of the endometrium. The tissue is processed and again is analyzed microscopically. The endometrium is graded on a scale from 1 to 3. A Grade 1 uterus is considered normal with an 80-90% expected foaling rate. A Grade 2a endometrial biopsy score indicates the presence of mild to moderate inflammatory changes with a 50-80% chance of carrying a foal to term. A Grade 2b biopsy score has moderate to marked inflammatory changes and indicates a mare has approximately a 10-50% chance of carrying a foal to term. Lastly, a Grade 3 uterine biopsy score indicates severe and permanent inflammatory changes that indicate the mare has less than a 10% chance of carrying a foal to term.
Nutrition: Mares enter the breeding season from a variety of different backgrounds. Mares should be grouped according to physiological status. Maiden mares, barren mares and lactating mares have different nutritional requirements. Segregating these groups will allow you to feed the different groups appropriately so that they will enter the breeding season with ideal body weights.
Research has shown that body condition has an effect on conception rates. Body condition scores, which estimate the amount of fat on a horse’s body, range from 1 (emaciated) to 9 (obese). Mares maintained in a moderate condition (Body Condition Score of 5-6) will begin to cycle earlier in the year and will generally become pregnant earlier and have higher pregnancy rates than thin or obese mares. Total daily feed intake by non-pregnant mares (hay and concentrate) normally ranges from 1.5 to 3.0% of body weight, with 2% of body weight being average. Lactating mares produce as much at 3% of her body weight a day in milk; therefore, a 1,000 pound mare will produce approximately 30 pounds of milk per day. This increases her nutrient requirements significantly – these mares should consume 2.5 to 3% of their body weight in feed. So a 1,000 pound mare would consume around 25 to 30 total pounds of feed a day of which approximately 10 to 15 pounds may be fed in the form a grain or other concentrates. It is advisable to consult with a nutritionalist where you purchase your feed, to help you design appropriate feed programs for your broodmares.
Mare Health: Disease challenge increases and immunity to disease decreases in horses being transported. If you are sending mares to a breeding farm, it is advisable to vaccinate your broodmare(s) 4 to 6 weeks before the start of the breeding season. Consult with your veterinarian regarding vaccination and deworming programs for each specific group of mares. In addition, a current Coggins’ will be required under most circumstances when breeding to a commercial stallion. Many breeding farms also require that you have the mare’s hind shoes removed before presenting her to the stallion.
Artificial Lighting: The majority of breed registries recognize that at the first of the year, all horses will be consider 1 year older; therefore, for these breeds, the operational breeding season starts approximately February 15th. By increasing the amount of time your mares’ are exposed to light will simulate the onset of spring and induce normal estrous cycles earlier in the year. On December 1st, if you expose your mares to a lighting program that extends the simulated “day length” to a total of 16 hours, by February 15th, your mares should be undergoing regular, predictable heat cycles. Mares may be housed in any type of facility for the lighting program, such as stalls, indoor arenas, or outdoor pens with over-head lights. The general guideline for a successful light program is that a person should be able to easily read a newspaper in any area that the mares are housed.
In summary, evaluating your mare’s reproductive potential and planning a health maintenance program for her is vital to prepare her for the upcoming breeding season. It is important to communicate openly and often with your veterinarian and stallion agent so that plans are made and problems are efficiently resolved well in advance of the anticipated breeding dates.
Vaccinations for Pregnant Mares
Tuesday, December 13, 2011
It is important to vaccinate your broodmares 4 to 6 weeks prior to foaling. This will not only boost the mares immunity for her own protection; it will help to maximize the amount of immunity she will pass on to the foal. However, it is important to understand that vaccination of the mare alone is not enough to provide foals with sufficient protection. All foals must also receive adequate amounts of colostrum within the first 24 hours of life.
It is recommended that mares receive ALL of the following core vaccinations prior to foaling:
Tetanus: 4 to 6 weeks prior to foaling. If the mare has not been vaccinated for tetanus previously, she will need 2 vaccinations 4 weeks apart prior to this time.
Eastern/Western Equine Encephalomyelitis: 4 to 6 weeks prior to foaling. If the mare has not been vaccinated for Eastern/Western Equine Encephalomyelitis previously, she will need 2 vaccinations 4 weeks apart prior to this time.
West Nile Virus: 4 to 6 weeks prior to foaling. If the mare has not been vaccinated for WNV previously she should be vaccinated immediately and again 4 to 6 weeks prior to foaling.
Rabies: 4 to 6 weeks prior to foaling, regardless of vaccination history. If the mare has not been vaccinated for rabies previously she should be vaccinated immediately and again 4 to 6 weeks prior to foaling.
Rotavirus: This is a 3 dose series administered at months 8, 9, and 10.
Equine Herpes Virus: This is a 3 dose series administered at months 5, 7, and 9.
Equine Influenza: 4 to 6 weeks prior to foaling. If the mare has not been vaccinated for Influenza previously, she will need 2 vaccinations 4 weeks apart prior to this time.
The following vaccinations are not part of the ‘core vaccination regimen’; it is recommended that you consult your veterinarian to determine if the following vaccinations should be administered to your horse prior to foaling:
Strangles: 4 to 6 weeks prior to foaling. If the mare has not been vaccinated for Strangles previously, she will need 2 vaccinations 4 weeks apart prior to this time.
Botulism: 4 to 6 weeks prior to foaling. If the mare has not been vaccinated for botulism previously, she will need a 3 dose series administered at months 8, 9, and10. This vaccination is for mares that will be in Kentucky for breeding.
Colostridium: This vaccination is administered on farms where clostridial diarrhea is common in foals. It is administered 3 to 6 weeks prior to foaling, regardless of the vaccination history.
http://www.aaep.org/core_vaccinations.htm
Corey D. Miller, DVM Diplomate ACT
Amanda Ramseyer, DVM
Equine Rabies in Marion County
Monday, November 28, 2011
On Sunday, November 20, 2011 a yearling Thoroughbred filly was admitted to the Equine Medical Center of Ocala with a two day history of high fevers, aggressive behavior and symptoms consistent with colic. As a result of her behavior at presentation, this horse was considered to be a rabies suspect. Precautions were immediately taken to reduce the risk of exposure to our staff. Within 12 hours of admission, the filly became more aggressive towards our medical staff and also began to bite her own limbs. As this behavior escalated, we sadly decided that euthanasia was the only humane thing to do for this filly. Post-mortem testing, performed at the Florida Department of Health in Jacksonville, FL, found the horse to be positive for the rabies virus.
Rabies is primarily a disease of wildlife, found mostly in raccoons, skunks, foxes and bats. Turn-out adjacent to wooded areas, and in pastures that are not regularly maintained, may lead to a greater risk of equine exposure; however, the rabies positive horse treated at EMCO had only limited access to turnout. This demonstrates the importance of vaccination against rabies in all horses, regardless of the environment in which the horse is boarded.
In horses, the acquisition of rabies is usually associated with bites on the muzzle, face and lower limbs. Following the bite, the virus migrates to the brain, through the nervous system, where it causes fatal encephalitis. Rabies can be difficult to diagnose as clinical signs can be variable and are often similar to several more common diseases. Initial signs can include behavioral changes, dullness and depression. Other clinical signs include salivation, anorexia, colic, difficulty swallowing, lack of coordination, aggressive behavior, self mutilation and excitability. Following the onset of clinical signs, death typically occurs within 3-5 days. Virus shedding is highest when the horse is exhibiting clinical signs.
Currently no laboratory testing exists to confirm rabies on a live animal; diagnosis can only be confirmed post-mortem. A horse owner should call his /her veterinarian immediately if he/she suspects that their horse could have rabies.
While rare in horses, rabies is 100% fatal, but can be easily prevented with a proper vaccination schedule. The rabies vaccine is inexpensive and highly effective. Please take this opportunity to consider updating your horse’s vaccination status. The American Association of Equine Practitioners (AAEP) recommends that an annual rabies vaccination be a core vaccine for all horses.
J. Barry David, DVM, Diplomate ACVIM
Marshall Stevens, DVM
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The laboratory at the Equine Medical Center of Ocala is one of few laboratories in the Southeast United States that performs the screening test for NI.
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The Coggins Test is documented proof that your horse is negative for equine infectious anemia (EIA). It is required to accompany a Health Certificate when shipping your horse from state to state, and when shipping to certain events and facilities within your home state.
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““IRAP” or Interleukin-1 Receptor Antagonist Protein (IRAP) is an exciting new articular therapy available at our hospital.
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“Equine Medical Center of Ocala is proud to be a registered facility for the use of stem cell technology.