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Equine Gastric Ulcer Syndrome
Dr. Kathy Samley
>>>>>Equine gastric ulcer syndrome is a common condition in horses and foals. While any horse can develop gastric ulcers, they tend to be more common in horses in high levels of work. Studies have shown that the prevalence of gastric ulcers can be as high as 60-90% in show horses and thoroughbred racehorses. The equine stomach consists of two sections, the squamous (non-glandular) portion and the glandular portion. The two sections are separated by a line called the margo plicatus. Ulcers in the squamous portion of the stomach develop from the excess production of gastric acid, which damages the squamous mucosa leading to the development of an ulcer. The glandular portion of the stomach has a protective coating that contains bicarbonate and other substances to buffer the gastric acid, making it less prone to ulceration than the squamous portion. Ulcers in the glandular part of the stomach are less well defined and research is still being done to investigate their causes and pathophysiology. Risk factors for development of gastric ulcers include feeding a high starch diet, feeding a large amount of grain at a time, strenuous exercise, and stressful events such as traveling or illness. Gastric ulcers can present with a wide variety of different signs depending on the horse. Common signs include changes in behavior, decreased performance or reluctance under saddle, poor appetite, mild weight loss, and mild episodes of colic.>
How are gastric ulcers diagnosed?
The only way to definitively diagnose gastric ulcers is with a gastroscopy procedure. This procedure can be done either on the farm or in the hospital. The horse must be fasted overnight so that their stomach is empty for the procedure. For the exam, the horse is sedated and a small camera is passed up the horse’s nose, down the esophagus, and into the stomach. The stomach is then inflated with air so that the entire stomach can be visualized. The parts of the stomach that are examined include the cardia (entrance to the stomach), the greater and lesser curvature, and the pylorus (where the stomach exits into the small intestine). Before the gastroscope is removed, the extra air is removed from the stomach to prevent colic due to gastric distension.
Gastric ulcers are graded on a scale of 1-4 based on their severity. Grade 1 ulcers are the most mild and consist of areas of reddening or hyperkeratosis of the mucosa. Grade 4 ulcers are the most severe and consist of extensive or actively bleeding ulcers.
How are gastric ulcers treated?
The main treatment for gastric ulcers is omeprazole, commonly known as Gastrogard or Ulcergard. Omeprazole is a proton pump inhibitor which blocks the enzyme that releases gastric acid into the stomach and therefore helps to decrease the acidic environment of the stomach. For most ulcer types, typical treatment includes administering a full tube of omeprazole once a day for 28 days. Before the end of the omeprazole treatment, a recheck gastroscopy is recommended to ensure complete healing of the ulcers. For severe ulcers, sucralfate may be used as part of the treatment regimen. Sucralfate binds to the ulcer and forms a protective barrier from the acidic stomach environment.
How can I help prevent my horse from developing gastric ulcers?
If your horse is prone to gastric ulcers, there are several steps that can be taken to help prevent recurrence of ulcers in the future. A preventative dose of omeprazole (250 lb dose or ¼ tube for a 1000 lb horse) can be given before stressful events such as traveling, competitions, or switching barns. Since omeprazole takes three days to reach its full effect, this should be started at least three days prior to the event and continued for the duration of the event. Feeding a higher fiber, low starch diet will lower the gastric pH, and help to prevent ulcers. Hay or pasture should be made available as frequently as possible. Feeding hay in a nibble net is a good way to provide continual access to small amounts of hay throughout the day. If possible, hay should be fed before grain meals to provide a buffering effect. Additionally, there are many supplements available that contain antacids. These supplements can be fed with every grain meal to help buffer the acidic environment of the stomach.
Esophageal Obstruction in the Horse
Written by Intern Dr Laura Wodzinski
Imagine you just finished feeding your horses and are heading out of the barn when you hear coughing. You go to investigate further and find that in addition to the retching, Mr. Ed has feed material coming out of his nostrils and is salivating excessively. What should you do next?
Call a veterinarian!
Mr. Ed is most likely experiencing an esophageal obstruction, or choke. Choke severity can be very variable depending on the what the horse is choking on and the reason for the choke. When you first recognize a choke has happened remove all feed, hay, and water. Further attempts by the horse to drink or eat could increase their risk of aspirating foreign material into their lungs and subsequently developing a pneumonia.
Why do horses choke?
There are several factors that can predispose a horse to choking. Geriatric horses are commonly associated with choke since they often have poor dentition and decreased saliva production. Horses that bolt their food can be at greater risk of choke, especially when fed a pelleted grain that expands in the lumen of the esophagus when it comes in contact with the saliva. For these horses, placing large rocks in their feed bin can force them to eat around the rocks and slow down their intake. Other factors that can play a role in choking is feeding a sedated horse. Horses can choke on any feed material including beet pulp, hay, pelleted feed, or bedding. The two most common regions of the esophagus where feed material gets obstructed is the proximal esophagus, or the part closest to the head, and the segment just cranial to the thoracic inlet, or the region just before the esophagus enters the rib cage.
Do we need to do the Heimlich maneuver?
Luckily, to relieve choke we do not need to perform the Heimlich maneuver. Initially, your veterinarian will sedate the horse to lower their head, reduce anxiety, and relax the esophageal muscles. A long nasogastric tube is passed into their esophagus until resistance is felt, presumably the area of obstruction, and water can be used to lavage the obstruction while gently pushing it towards the stomach. It will be important to keep their head down as much as possible while relieving the choke to decrease the risk of the horse aspirating any liquid. Additional medications, such as Buscopan, can be used to relax the esophagus to aid in the movement of the food bolus. Another theory, is giving a drug to decrease smooth muscle tone such, as oxytocin. This drug can be associated with transient abdominal discomfort and sweating and is not safe to use in pregnant mares.
If these initial steps do not resolve the choke, the veterinarian may need to provide intravenous fluids to maintain adequate hydration since you horse will be unable to drink water while choked. Additionally, if the choke cannot be relieved with sedation, general anesthesia may be needed to get more relaxation and a more aggressive lavage. If all attempts to dislodge the choke are unsuccessful, surgical management can be pursued as an emergency procedure.
What are the complications that can be associated with a choke?
A common complication of choking is aspiration pneumonia, or an infection in the lung caused by inhaling food particles and material. Prophylactic antibiotic administration, either with oral tablets or injectable formulations, are typically prescribed following a choking incident to prevent this possible serious complication. It is important to monitor your horse for coughing, increased respiratory rate, appetite, lethargy, and fever for 5-7 days following a choking incident so you catch the early signs of pneumonia. If there is great concern for aspiration, a thoracic ultrasound can be performed to look at the lining of the lungs. Additionally your veterinarian will want to listen to the horse's lung sounds to see if there are any crackles or wheezes which are an indication of pathology in the. Factors that increase the risk of aspiration pneumonia include the duration of the choke, more attempts to drink while choked, and the horse having their head elevated while choking..
With a more difficult choke, an endoscopic examination, or passing a camera through the horses nose and into their esophagus, may be warranted. By visualizing the esophagus on the camera, the integrity of the esophageal tissue can be assessed for irritation or damage that can be associated with choking. When there is damage to the esophageal tissue, the area will heal by laying down scar tissue. This scar tissue is less elastic than the healthy esophageal tissue and can form a stricture, or narrowing of the esophagus. If a stricture forms then food passage down the esophagus will continue to be an issue and a feeding program will need to be adjusted accordingly.
Days Following the Resolution of Choke
After a horse has choked it will be important to introduce food very gradually and as a soupy gruel. The esophagus will need to have time to heal therefore making the food into a slurry will make passage through the esophagus easier. Prophylactic antibiotics as well as an anti-inflammatory drug, such as banamine, will typically be prescribed following the incident. Additionally, rectal temperature monitoring and close monitoring for signs of pneumonia will be crucial in recognizing any post-choking complications. A first time choke incident with no complications has an excellent prognosis. With complications of stricture or aspiration pneumonia, the prognosis decreases.
Understanding Equine Cellulitis
By Lauren Hughes, DVM
Cellulitis can be a relatively common and frustrating condition affecting the limbs of horses. The condition results from inflammation and infection of the subcutaneous tissues that lie beneath the skin. It commonly affects only one limb at a time and is most likely in the hind end.
The typical presentation of cellulitis is very prominent swelling of a limb that is often associated with lameness. The lameness is normally quite severe, with some horses even refusing to bear weight on the limb, and owners notice that it develops quite rapidly. Either areas of the limb or the entire limb will swell up and can reach 2-3x the normal size. The affected limb often becomes very warm and painful to the touch, and pitting edema may be present. A fever may be present and the horse may exhibit other signs of not feeling well including being lethargic and off feed.
Cellulitis cases can have no known trigger or may follow an insult including surgery, joint injections, wounds or trauma. The most common bacteria to be isolated from these cases are Staphylococcus spp. which normally inhabit the skin. These bacteria then can enter the deeper tissues and lead to infection through some break in the skin barrier. Edema in these tissues then forms when the bacteria and the toxins they release create an inflammatory response. This leads to blood vessels and lymph vessels becoming leaky and tissue building up in the subcutaneous tissue.
It is very important to get your veterinarian involved when a case of cellulitis is suspected as prompt diagnosis and treatment are crucial to successful recovery. Your veterinarian may suspect cellulitis on physical examination when a horse has a swollen, warm, painful limb and is exhibiting prominent lameness. It is important to rule out other causes of severe lameness and limb swelling including joint infections and fractures as well. Supporting diagnostics are then used to confirm and assess the extent of the condition. Ultrasound can be very useful in looking at the subcutaneous tissues and highlighting the presence of edema, seen as fluid accumulation within the tissue layers. Bloodwork will often show an elevation in the fibrinogen level, a marker used to assess inflammation, and/or changes to white blood cell counts.
The main stays of cellulitis treatment focus on eliminating the infection from affected tissues and supportive care to decrease the limb swelling. Broad spectrum antibiotics are commonly used to help clear the infection. NSAIDs can also be used to help control any pain and inflammation. Hydrotherapy with cold hosing, bandaging, sweat wraps and hand-walking or lunging are often crucial components of treatment and are used in combination to help reduce the swelling of the limb. Treatment can often be quite frustrating as many of these cases can take a while to resolve and full resolution is not always achieved.
Prompt and thorough treatment is very important in these cases as devastating and life threatening complications can follow a case of cellulitis. Some horses undergo very severe and deep infections that cannot be corrected with medical management alone and surgical debridement or drainage is necessary. In other cases, thrombosis of vessels can occur which leads to necrosis of tissue and skin sloughing wounds. These wounds can involve important underlying structures and may require a long and expensive period of intensive wound care and bandaging to resolve. Lastly, laminitis can occur in the affected limb due to damage to the coronary band or can develop in the contralateral limb due to the extra stress placed upon that limb.
Although survival rates are quite high and treatment is often successful, prognosis for a full recovery is not guaranteed. Some horses may have recurrence of the infection or suffer from lameness when returning to normal work loads after the initial episode. Chronic cases will often lead to a permanently thicker leg due to the presence of scar tissue. This can permanently affect the horses’ ability to normally drain the lymphatic system. Client compliance and early detection are crucial in recognizing chronic recurring cases and prompt treatment will help prevent episodes from progressing. Horses that are prone to recurring episodes are often maintained on strict exercise programs and extra care is taken to ensure proper hygiene and prevent exposure to infections.
If you have any other questions regarding cellulitis, please feel free to contact New England Equine Medical & Surgical Center.
Barr, Bonnie. Cellulitis. Rood & Riddle. 2011.Webpage.
Fig 1: Cellulitis. Anoka Equine Veterinary Services. 4 August 2014. Webpage.
Getman, Liberty M. Alternative Therapies for Cellulitis. ACVS Proceedings. 2011. Print.
Holmes, Peter. Lymphangitis in Horses. Merck Veterinary Manual. 2011. Webpage.
Reed, Bayly and Sellon. Equine Internal Medicine- 3rd Edition. St. Louis: Elsevier, 2010. Print.
Habronemiasis: A Sore Summer Topic
Habronemiasis goes by many names such as summer sores, jack sores, swamp cancer or bursatee. Habronemiasis is very common in horses in the South Eastern U.S., but can be seen in other areas of the country. Larvae of the stomach worm Habronemaspp. cause this skin disease. The adult nematodes cause parasitic infestation in the stomach of the horse, which is part of the nematode’s lifecycle. Infestation of the adult stomach worms is called gastric habronemosis, and it rarely causes clinical signs aside from a mild gastritis (stomach inflammation). The cutaneous form of the disease is caused by larvae of the stomach worm that get deposited into a wound or moist areas of the body by the fly (the intermediate host), and cause significant skin reactions. The larvae emerge from flies that feed on wounds or secretions from around the eyes or genital region. The most commonly affected areas are the corner of the eye (where tearing occurs), the sheath and urethral process of the male horse, and occasionally the lower extremities. These are also the areas where horses cannot ward off these vector flies by the swishing of their tail. The migration of the larvae in the tissue causes a hypersensitivity reaction as the larvae start to die. This reaction is granulomatous in nature. Horses are very good at developing what is colloquially known as ‘proud flesh’, which is an excessive development of a type of very vascular tissue called granulation tissue. It is part of the horse’s immune defense but often causes delayed wound healing due to the exuberant, extensive nature and overgrowth of the tissue. Thus, these sores take on the characteristic of ulcerative, nodular and tumorous masses (See Figure 1).
Figure 1: Cutaneous habronemiasis at common locations in the horse. From left to right ocular habronemiasis at the medial canthus of the eye, genitalia habronemiasis on the urethral process and sheath of a male horse. Photos courtesy of Atlanta Equine Clinic.
Diagnosis is based on clinical signs of non-healing ulcerative granulomas, which occur normally in the aforementioned locations. They often appear greasy, and reddish-brown in color. Occasionally you can see small (rice-sized) yellow calcifications, which are the dead larvae residing in the lesion. The only way to truly confirm habronemiasis is to take a biopsy of the affected tissue. Other skin lesions that can have a similar clinical appearance include squamous cell carcinoma, equine sarcoids, overgrowth of granulation tissue (proud flesh) following a wound, rain scald or ringworm. Thus, definitive diagnosis obtained by a skin biopsy is ideal in guiding treatment and future prevention. Skin scrapings and cytology rarely show larvae, and confirm a diagnosis. Biopsies, however, often show the larvae as well as an eosinophilic infiltrate, which is a type of local white blood cell reaction that occurs with parasite infection.
Treatment by prevention is ideal as these skin lesions can be very difficult to eliminate. Prevention predominantly involves fly control. By decreasing the horse’s exposure to flies this disrupts the Habronema lifecycle. These prevention measures include the frequent use of fly repellents, and adequate and careful disposal of horse manure. The eggs reside in the manure, and therefore, removal of manure will decrease the incidence of flies ingesting the egg, and then incubating the larvae until infection in the horse occurs. Regular anthelmintic (de-worming) treatment is another method to prevent the lifecycle from perpetuating. There are some topical treatments that have varied effects. Organophosphates have been applied topically in attempt to kill the larvae. Topical corticosteroids and anti-inflammatories are often not curative, but may control inflammation in the area. At times surgical removal or cauterization of the exuberant granulation tissue is necessary. The treatment of choice is Ivermectin, which is an anthelmintic. After one dose any infection of the species in the stomach will be resolved, and subsequent doses will help to promote healing in the cutaneous tissue. Rarely, if the migrating larvae are not already dead at time of treatment, and Ivermectin is administered then there may be temporary exacerbation of the lesions as the larvae presumably die. Spontaneous healing can be expected at times after such administration.
Cutaneous habronemiasis that affects the genital area such as the prepuce (sheath) or the urethral process, and glans penis can be particularly difficult to treat. They appear as thick or firm and irregularly shaped masses, and are often referred to as ‘Kunkurs’. Clinical signs in this area can include bleeding readily on manipulation due to the vascular nature of the infected tissue, itchiness, and spraying or frequent and difficult urination. Spraying is especially common if the urethra is affected. It is common in colder regions for the lesions to disappear in the winter and recur or increase in size in the warmer summer months. Despite the similar pathogenesis, these lesions are difficult to treat and often require surgical removal or amputation. Again, Ivermectin treatment can prove beneficial in these cases.
Lastly, in ocular habronemiasis the lesions can progress to the conjunctiva of the medial canthus, the third eyelid, and the eyelid proper. Clinical signs in this manifestation include blepharospasm (excessive squinting), and severe epiphora (excessive tearing). Horses tend to rub these areas, and this causes more tissue damage, which in turn, creates more sites for potential larvae deposits. Again, corticosteroids may provide temporary relief, but the best method is prevention. A fly mask or roll on fly repellents for around the eye are an ideal way to prevent further spread, and infestation. Chronic sores may require surgical intervention.
Overall, it is important to closely inspect your horse in the summer months for any new wounds and skin abrasions. Quick and effective cleaning and topical treatment of these wounds can prevent Habronema larvae from seeding, and causing a much greater problem. In addition, fly control and regular anthelmintic therapies are key to preventing this difficult and debilitating skin condition.
Radostitis, Otto. Verterinary Medicine: A Textbook of the Disease of Cattle, Horses, Sheep, Pigs and Goats, 10th ed. Philadelphia, Saunders, 2007. PDF.
Knottenbelt, DC. Diseases and Disorders of the Horse, Saunders, 2003.
Kahn, C. The Merck Veterinary Manual, 10th ed. Kenilworth, Merck sharp and Dohme Corp, 2015.
Local Horse Trainer Selected for Extreme Mustang Makeover
Kendra Hillier from Rockport, MA has been selected to compete in the Extreme Mustang Makeover held August 5-6, 2016, at the Topsfield Fair Facility in Topsfield. Trainers will have approximately 100 days to gentle a randomly assigned wild horse they picked up in April and compete for an estimated purse of $20,000 in prize money as well as a custom-made Gist belt buckle.
Kendra Hillier has had a lifelong passion for horses. She grew up riding as many horses as she could in Rockport, MA, and gained much experience from riding a huge variety of horses not having the funds to purchase her own until her mid twenties. At 30, Kendra manages a horse farm on over 120 acres in Berlin, MA, she teaches horseback riding lessons at several locations to students of all ages and experience levels, and she has a few horses in training- both Dressage and Western disciplines. In addition, Kendra has been investing several hours per day with her wild mustang, Allura, who is boarded at a quiet, private stable in Lunenburg, MA. Kendra picked up her untouched mustang on April 16, 2016 in Orange, MA and the journey began. It took about a week and a half before Kendra was able to get a halter on the fearful and unsure mare, and even then, Kendra had to create a custom halter for her that she could get on without touching the horse’s most guarded area- her muzzle. About 2 months later, the little mustang mare follows Kendra everywhere. Allura nickers for treats and attention, and gently rubs her face on Kendra when she’s got an itch. The bond of trust and respect that these two have built is something very special. Recently, Kendra was able to take her wild mustang out to a Reining competition at the Big E in Springfield for a long weekend- Allura was great under Kendra’s lead, and the pair even entered the ‘sit a buck’ class, where the rider walk, trots, and canters their horse bareback, trying not to lose a dollar bill that’s placed under the rider’s leg. Kendra has fallen in love with her 6 year old mustang mare from Divide Basin, WY, and hopes to adopt her at the end of the competition.
The purpose of the competition is to showcase the beauty, versatility and trainability of these rugged horses that roam freely on public lands throughout the West, where they are protected by the BLM under federal law. The BLM periodically removes excess animals from the range to ensure herd health and protect rangeland resources. Thousands of the removed animals are then made available each year to the public for adoption. Over 6,200 Mustangs have been adopted through Mustang Heritage Foundation events and programs since 2007.
The Mustangs competing in the Extreme Mustang Makeover challenge are mares, and the horses, which were virtually untouched prior to the April pick-up, will compete in Topsfield in August. The trainers and Mustangs will compete in a series of classes that will showcase their new skills. The horses will compete in handling and conditioning, a pattern class and a combined leading and riding class. The top-10 competitors will then compete in the freestyle finals. Tickets and event information about the Massachusetts Extreme Mustang Makeover are available at http://extrememustangmakeover.com/extreme-mustang-makeover-massachusetts/
Mustangs competing in the Extreme Mustang Makeover will be available for adoption through an adoption auction on August 6. Adoption fees will be set by competitive bid. To qualify to adopt, individuals must be at least 18 with no record of animal abuse. In addition, adopters must have suitable facilities and can adopt no more than four animals. Adoption applications will be approved on site by the Bureau of Land Management during the event.
The Extreme Mustang Makeovers are made possible through a partnership with the Bureau of Land Management and the generosity of sponsors Western Horseman, Ram Rodeo, Vetericyn, Martin Saddlery and Classic Equine, Resistol, and RIDE TV.
About the Mustang Heritage Foundation
The Mustang Heritage Foundation is a 501 (c)(3) public, charitable, nonprofit organization dedicated to facilitating successful adoptions for America’s excess mustangs and burros.Extreme Mustang Makeovers are designed to showcase the recognized value of Mustangs through a national training competition. The Mustang Heritage Foundation is celebrating the 10th Anniversary of the Extreme Mustang Makeover in 2016 with 10 national event stops! Train, adopt or attend to show your support for the American Mustang. For more information, visit http://www.mustangheritagefoundation.org
About the Bureau of Land Management
Since 1971, when Congress passed the Wild Free-Roaming Horses and Burros Act, the BLM has successfully placed over 235,000 wild horses and burros into private care.The BLM manages more than 245 million acres of public land, the most of any Federal agency. This land, known as the National System of Public Lands, is primarily located in 10 Western states, including Alaska. The BLM also administers 700 million acres of sub-surface mineral estate throughout the nation. The BLM's mission is to manage and conserve the public lands for the use and enjoyment of present and future generations under our mandate of multiple-use and sustained yield. In Fiscal Year 2014, the BLM generated $5.2 billion in receipts from public lands. For more information, visit blm.gov.
2016 Extreme Mustang Makeover Schedule
March 11-12 Gonzales, LA
April 22-23 Queen Creek, AZ
May 6-7 Jacksonville, FL
May 20-21 Ft. Collins, CO
June 18-19 Reno, NV
July 14-16 Sedalia, MO
July 29-30 Nampa, ID
August 5-6 Topsfield, MA
August 25-27 Virginia Horse Center
September 15-17 Fort Worth, TX
From Breeding to Foaling
The essentials to properly managing your broodmare
The first step of deciding to breed your mare or buying a brood mare is to determine whether she is able to conceive and if she is able to maintain a pregnancy. A breeding soundness examination is an important step to ensure you have a fertile mare to breed. Your veterinarian can perform this and it will consist of a detailed general and reproductive history, a thorough general physical examination, body condition scoring, and a comprehensive reproductive examination. Good body condition is necessary for fertility and maintaining a pregnancy. Research indicates that mares with a body condition score (BCS) of 6-7 have higher pregnancy rates. This is based on a scale from 1-9 with 1 being emaciated and 9 being severely obese. Additionally, overall good health is necessary as any illness or injury can result in decreased fertility.
The reproductive examination will include evaluation of the external genitalia, a speculum examination of the vestibule, vagina, and cervix, and a transrectal reproductive ultrasound to examine the uterus for fluid, cysts, or any other abnormalities. A uterine cytology, culture, and biopsy will be performed as well to determine if endometritis (inflammation and infection of the uterus) is present and if the endometrium is capable of maintaining a pregnancy. The endometrial biopsy is probably the single most important indicator of a mare’s ability to conceive and maintain a pregnancy. The biopsy results are placed into 3 categories: 1) 80-100% chance of pregnancy 2a) 50-80% chance 2b) 10-50% chance 3) Less than 10% chance.
Once your mare has “passed” the breeding soundness examination, you may start the breeding process. You first have to choose the stallion and decide whether you would like to breed via live cover or artificial insemination. Your veterinarian will need to check your mare with transrectal ultrasound periodically to determine when she is in estrus (heat) and the best time to breed. Depending on the tendency of the mare to develop post-breeding endometritis, she may need non-steroidal anti-inflammatories (NSAIDs) or corticosteroids at the time of breeding.
The vulvar conformation of the mare is very important in maintaining a pregnancy. If 2/3 of the vulvar lips are above the pelvic brim fecal contamination of the vestibule and vagina is more likely, which can result in inflammation and prostaglandin release that is not compatible with pregnancy as well as provide an avenue for ascending infection. Additionally, mares that are windsuckers will also have inflammation of the vagina and vestibule resulting in prostaglandin release. A caslicks procedure can be performed on these mares at the time of breeding or at pregnancy diagnosis. A caslicks is where the edges of the vulvar lips are incised and sutured together to prevent fecal contamination and/or air irritation. The caslicks will need to be removed just prior to foaling.
The mare should be checked for pregnancy around 14 days after ovulation. The uterus should be thoroughly evaluated for the presence of twins. If two pregnancies are present, one will need to be reduced at that time, as the equine uterus does not tolerate twins well. At the time of reduction, it would be wise to administer a NSAID and supplement with altrenogest (ex. Regu-Mate) in order to provide a healthy uterine environment for the remaining embryo. Normal healthy broodmares do not require altrenogest supplementation; however, if any irregularity is present at the 14-day pregnancy check, such as poor uterine tone, increased uterine fluid, decreased progesterone, odd appearance to the corpus luteum, or any other worrisome finding, altrenogest supplementation until day 120 of gestation may be warranted.
14-day equine pregnancy ultrasound
The fetal heartbeat is present by day 25 of gestation. An ultrasound to evaluate the presence of fetal heartbeat should be performed around that time. Fetal sexing can be determined via ultrasound in two windows: day 58-73 or day 110-120 of pregnancy. Further recheck ultrasounds can be performed periodically throughout pregnancy; the frequency depends on the individual mare and veterinarian preference.
Vaccinating broodmares is imperative for disease prevention, passing immunity to the foal, and prevention of abortion. Equine herpes virus one (EHV-1) is a major cause of abortion in mares. The virus is inhaled and without adequate local immune protection it can cause viremia (systemic illness), which results in uterine ischemia (lack of blood flow) and death to the fetus. Pregnant mares should be vaccinated at 5, 7, and 9 months of gestation. It is possible, although rare, for properly vaccinated mares to abort due to EHV-1. Therefore, it is essential to institute management tactics to prevent infection as well. Such methods include separating all pregnant mares from the rest of the herd as well as isolating mares that have aborted and any horses those mares have come in contact with.
It is important to booster all routine vaccines 4-6 weeks prior to the expected foaling date so that adequate antibodies are transferred to the foal in the colostrum. Routine vaccination includes tetanus, rabies, eastern equine encephalitis, western equine encephalitis, Venezuelan equine encephalitis (if it affects that area), and west nile virus. Additionally, if the farm has a known problem with Rotavirus, which causes profuse watery diarrhea in foals, then the mare should be vaccinated at 8, 9, and 10 months of gestation. Other vaccinations, such as influenza, strangles, botulism, and Potomac Horse Fever, can be discussed on an as needed basis with your veterinarian.
Excellent nutrition based on the mare’s metabolic needs for her reproductive stage is a necessity. Mares have to be in good body condition for fertility and they must maintain the body condition throughout pregnancy. Mares have similar metabolic needs through the first 8 months of gestation. Late gestation dramatically increases metabolic needs of the mare due to the fact that 60-65% of fetal growth occurs during this period. Consequently, the mare will need a significant increase in feed during late gestation (9-11 months). Lactation is also a very metabolically demanding time. Mares will produce 3% of their body weight in milk on a daily basis during the first 12 weeks of lactation; this means the mare needs 70% more calories than her maintenance diet. Determining a feeding regiment that is right for your mare(s) can be done with the consultation of your veterinarian and/or an equine nutritionist. Ensuring the mare has an oral exam annually and teeth floated as needed is important to assist in the maintenance of body condition.
One crucial aspect of nutrition is to keep the mare off of tall fescue grass during breeding and throughout gestation. There is as symbiotic relationship between fescue grass and an endophyte fungus, Acremonium coenephialum, which results in a variety of negative effects on gestation and the foal. Mares who consume this grass can have decreased fertility rates and/or early embryonic death. Pregnant mares consuming the grass can also suffer from prolonged gestation, abortion, dystocia, premature separation of the chorion, placentitis (thickening of the placenta), retained placenta, and agalactia (suppressed milk production). Negative effects on the foal include abnormal maturation, weakness, reduced immunity, and starvation from agalactia. If it is not possible to prevent the broodmare from grazing fescue, there are drugs available to counteract the effects, such as domperidone and reserpine.
Routine deworming of the mare is important prior to and during gestation to produce a healthy foal. The best deworming protocol for your horse/herd should be determined with your veterinarian. It is recommended to deworm at least twice a year. Most dewormers are safe to use during pregnancy; however, it is critical to check the label before administering any drug to a broodmare. It is a common practice to give the mare ivermectin on the day of foaling to decrease the transmission of Strongyloides westeri, which can be spread via nursing four days post foaling.
Lastly, it is essential to properly prepare your mare for foaling. It is wise to move the mare to a clean and dry location that can be closely monitored 4-6 weeks prior to the expected foaling date. This will allow her to acclimate to her environment as well as build up an immune response to that particular environment that she can then pass on to her foal. The mare’s udder and her underside where the foal may try to nurse should be cleansed. If a caslicks was performed, the vulva should be opened to prevent tearing at parturition. Knowing the signs of impending parturition will help to better predict the time of foaling. Physical changes include relaxation and edema of the vulva, mammary gland development, scant vulvar discharge, relaxation of the tailhead, and changes in the udder secretions.
Mammary gland development, also referred to as bagging up, and secretions are the most useful tools to predict impending parturition. The mammary gland begins developing one month prior to foaling and has a drastic increase in size within two weeks of parturition. The udder is typically engorged within days of foaling. Udder secretions may start as early as one month prior to foaling, and they will change from a clear or yellow color to white and milk-like. The appearance of waxy secretions on the teats usually occurs 1-4 days prior to foaling but can occur as early as 2 weeks. The waxy secretions are from early colostrum formation. Colostrum is the first milk the mare produces, and it contains all of the antibodies she will pass to the foal. Therefore, if the mare is leaking a significant volume several days to weeks prior to parturition, it is strongly encouraged to collect and freeze that colostrum so that it can be fed to the foal at birth to ensure adequate passive transfer. Mammary gland secretions can provide valuable information on impending parturition. There are several milk tests available to determine the electrolyte levels, which change related to fetal maturity and viability, and therefore are informative on the proximity of foaling.
When the mare is close to foaling, she should be closely monitored throughout the day and night. Commonly used monitoring systems include camera stalls and foal alert systems. The foal alert system involves suturing a device into the mare’s vulva that will separate and produce an alarm at foaling.
When the mare is suspected of foaling that evening, it is recommended to clean and dry the perineal region as well as to wrap the tail for a cleaner environment. There are three stages of parturition. Stage one is the preparatory phase, which can last 30 minutes to 4 hours. During this phase the mare can exhibit signs similar to colic, including flank watching, restlessness, raising and swishing the tail, and urinating small volumes frequently. This phase is very important for the repositioning of the fetus into the “diving position” pictured below. Stage two begins at the rupture of the chorioallantois allowing the allantoic fluid to escape the uterus, also known as the water breaking. This phase includes the expulsion of the foal. If there is a red bag present at the mare’s vulva it should be ruptured immediately. Instantly rupturing the membrane is essential to foal survival, as this is indicative of premature placental separation and lack of fetal oxygenation. Calling your veterinarian after the membrane is ruptured is strongly encouraged. If no red bag is present, the white amnion should appear at the vulva within 5 minutes of the water breaking. The foal will normally pass within 30 minutes. If the foal has not passed in that time or if there is no significant progress over 5-10 minutes, it is strongly encouraged to call your veterinarian for assistance. After the foal has passed through the mare’s pelvis, stage 3 begins. This stage consists of the expulsion of fetal membranes and uterine involution. There is a “1-2-3” rule to follow at this point. The foal should stand within the hour, nurse within 2 hours, and pass meconium within 3 hours. The mare should also pass the full placenta within 3 hours of foaling. The placenta can be tied to itself so it hangs just above the hocks to avoid being stepped on. If the placenta has not passed within 3 hours please contact your veterinarian immediately.
“Diving position” of the foal at birth
The umbilicus usually breaks when the foal attempts to stand or when the mare stands. If the umbilicus does not rupture on it’s own, it should never be cut as that can result in a patent urahcus and/or excessive hemorrhage. There is a pre-determined break site that is evident by a pale strictured area. This point should be identified and the forefingers are used to twist above and below taking great care not to pull excessively on the cord. Once the umbilicus has been torn, the stump should be closely evaluated for hemorrhage, urine leakage, or swelling before being dipped in a dilute 0.5% chlorhexadine solution.
Once the mare has passed the placenta it should be thoroughly evaluated to ensure all pieces are intact. It is crucial to the mare’s health that no pieces of placenta are retained within the uterus as this can result in severe systemic illness. Saving the placenta in a large bag within the refrigerator is recommended so that your veterinarian can evaluate it fully to look for any missing pieces and signs of placentitis. It is strongly recommended to have your veterinarian evaluate both the mare and foal within 12 hours of parturition to ensure they are both in good health and that the foal has adequate passive transfer.
If you have any questions or concerns regarding your mare or foal’s health please feel free to contact New England Equine Medical and Surgical Center.
Kristina McGinnis, DVM
New England Equine Medical and Surgical Center
1. >Brinsko, Steven P., Terry L. Blanchard, Dickson D. Varner, James Schumacher, Charles C. Love, Katrin Hinrichs, and David Hartman. Manual of Equine Reproduction. 3rd ed. Mosby Elseveir. Print.>