March 13, 2011 13:41
by Kentucky Equine Research Staff
Strangles is a bacterial disease that affects the upper respiratory tract and the lymph nodes in the head and neck. Common signs are fever, nasal discharge, and the formation of abscesses in the lymph nodes. These abscesses, which occur most often in the throatlatch or jaw areas, eventually burst and drain thick pus. Though the horse can appear quite ill, strangles is usually not fatal. However, strangles sometime moves into other areas of the horse’s body where it is generally much more serious and can cause death. The disease is highly contagious and is easily spread to other horses that come in contact with pus or nasal discharge.
A rapid diagnostic test for strangles has been perfected by a team of researchers from the University of Maine, Tufts University, and the University of Kentucky. Unlike previous tests that took several days to confirm a diagnosis of strangles, the new test produces results in a few hours. The test detects a specific protein on the bacterium Streptococcus equi subsp. equi, the cause of strangles....continue reading http://www.equinews.com/article/strangles-test-developed
March 10, 2011 18:05
“It’s really cold outside, it’s starting to snow again, and the wind is howling. Is my pasture-kept horse all right?” In all but the most extreme winter weather, the answer is “Yes.” Most horses are well-suited for staying healthy and comfortable in cold weather as long as owners provide them with proper care. Some horses may need additional help staying warm in bitterly cold, wet, windy weather.
The equine hindgut acts as an enormous furnace where the digestion of hay and other fibrous feeds produces a constant supply of heat from microbial fermentation. Owners need to be sure horses have an adequate supply of hay, increasing the amount as the temperature drops.
More heat can be produced by activity, including shivering. Pastured horses can be seen playing, bucking, and running from time to time, and this muscular exertion helps to keep body temperature stable. Short bouts of shivering do the same thing. Horses that shiver continuously in cold, wet weather probably need more hay, possibly a bit more grain, and access to shelter.
The horse’s winter coat is thick and dense. As long as it stays dry, it provides superior insulation. Natural oil tends to let rain and snow slide off, keeping moisture from penetrating deep into the coat. If you see snow building up on your horse’s back or rump, you are looking at proof that his body heat is not escaping through the hair to melt the snow.
When rain or wet snow manages to soak through to the horse’s skin, heat will be lost as the coat’s insulating ability decreases. Under these conditions, horses may need to wear a well-fitting waterproof blanket or have access to a windbreak or covered shelter.
Though horses sometimes stand in deep snow, their lower limbs and hooves almost never suffer damage from the cold. This is because the legs below the knees and hocks are made up mostly of bones and tendons, tissues that don’t freeze easily. In extreme cold temperatures, blood-shunting mechanisms in the hooves alter circulation patterns to preserve body warmth.
Regardless of the adaptations mentioned above, some horses may need additional help staying warm in bitterly cold, wet, windy weather. Very old, very young, sick, or extremely thin horses may need to be blanketed or brought into deep-bedded stalls to keep them from becoming dangerously chilled.
to read further: http://www.equinews.com/article/
March 2, 2011 21:30
Western Canada’s most common (and not so common) skin conditions.
Dr. Sue Ashburner still shudders when she describes the sight of one of her equine patients covered with thousands of bloodsucking ticks last winter. “We occasionally see wood ticks on horses during May and June, but I didn’t know what kind of ticks would be on horses in February,” admits Ashburner, a veterinary clinician at WCVM’s Large Animal Clinic in Saskatoon, Sask. Dr. Lydden Polley, a parasitologist at the College, soon solved the mystery: he identified the parasites as Dermacentor albipictus (Acari: Ixodidae), more commonly known as moose ticks. “It was the first time I ever saw a horse in this area covered in moose ticks,” says Ashburner. “That’s what I like about working on dermatology cases. There are always new things, and those cases challenge you to find out what you’re dealing with. Sometimes we never know the cause, but we usually know how to treat what we see.” At least once a week, Ashburner gets a chance to use her dermatological know-how on equine patients living around Saskatoon — an area that’s populated with horses of all breeds and disciplines. The clinic’s number of dermatology cases usually rises in the spring after horses shed their coats and owners suddenly notice lumps, bumps, growths or parasites that have shown up during the winter. Thanks to advances in diagnosing and treating equine skin conditions, veterinarians can offer clients more effective therapies and more understanding of what causes skin problems to develop. Most clients call for advice or to arrange for a veterinary visit, but some still insist on using their own home remedies that often makes Ashburner’s job tougher. “After they’ve scraped it, treated it or used ointments that burn the skin, it doesn’t look anything like it originally did. These remedies usually just make things worse.” While Ashburner isn’t expecting another moose tick infestation case soon, here are some common skin conditions that she and veterinary pathologist Dr. Ted Clark regularly see out in the field and in the pathology laboratory. Their comments accompany some additional information gleaned from the text, Equine Dermatology, co-authored by Drs. Danny Scott and William Miller Jr. • Dermatophytosis or ringworm is a fungal infection that’s transmitted by contact with infected hair, bedding, tack and grooming equipment. Ashburner often diagnoses multiple cases of ringworm in young horses living in close quarters throughout the winter months: the infection often goes unnoticed until horses shed their winter coats. The most consistent clinical sign is one or many circular patches of alopecia (hair loss) with variable scaling and crusting. But horses may also develop the classic ring lesion with a healed centre and fine follicular papules and crusts on the ring’s edges. Lesions are usually multiple, and they’re most commonly found on the face, neck, the sides and girth. The lesions usually go away within three months, but veterinarians often use topical and systemic treatments to help their patients’ response to the infection, to reduce the spread of the fungus and to speed up the healing process. • Sarcoids are the most common skin tumour of horses around the world. Veterinary researchers believe the cause of sarcoids is viral, and research has shown that bovine papillomaviruses (BVP) are commonly involved in sarcoid development. Lesions frequently show up in areas of a horse’s body after a wound or trauma, or they may also spread to other areas of the same horse or to other horses through biting, rubbing, tack, equipment and insects. Sarcoids occur anywhere on a horse’s body, but most lesions are found on the head, neck and ventral body surface. The lesions’ appearance can be verrucous (wart-like), fibroblastic (proud flesh-like), mixed verrucous and fibroblastic, and occult (flat). Sarcoids do not metastasize, and some tumours may disappear after several years. Depending on available resources, veterinarians can choose from surgical excision, cryosurgery, radio-frequency hyperthermia, laser therapy, radiotherapy, chemotherapy, immunotherapy or combinations of treatments. • Papillomas present in two different forms: as warts (viral papillomatosis) or as aural plaque (ear papillomas). Viral papillomas spread through direct contact or indirectly through contact with contaminated equipment or housing. Young horses often develop clusters of warts, usually on their muzzles or lips. “They bother the owner much more than horses,” says Ashburner. “If left alone, they tend to go away and you can’t rush them. People always buys potions and lotions, but they usually make no difference.” Aural plaques — white-greyish crusts commonly found in horses’ inner ears — don’t respond very well to topical treatments, and they rarely go away. Fortunately, these lesions are only a cosmetic problem. • Eosinophilic granuloma or nodular necrobiosis is an equine dermatosis most commonly seen in the spring and summer. These nodules are round, elevated, and occur as single or multiple lesions on the back, withers and neck. The lesions aren’t painful or itchy, and the overlying skin and hair coat are normal. Veterinarians can surgically remove one or several lesions, or treat multiple lesions with systemic glucocorticoids over several weeks. Some lesions undergo spontaneous remission in three to six months, while older or larger lesions must be surgically removed. • Allergic reactions show up as anything from bumps and wheals in all shapes and patterns to angioedema (swelling) involving the muzzle, eyelids, under the belly, legs or the entire body. These reactions result from insect bites, plants, drugs or vaccines, a change in feed, bedding or the horse’s environment. Gathering a thorough medical history is how veterinarians usually track down the source, says Ashburner. “It could be caused by a minor environmental change, a sudden hatch of bugs in the area. It really pays off to ask a lot of questions.” Ashburner and her colleagues usually try to eliminate the source of hypersensitivity or generally treat the horse to try and decrease its immune response. “One treatment that has worked quite well is to feed the horse raw linseed oil: its Omega 3 fatty acids help to decrease the animal’s hypersensitive response in the skin. That seems to calm things down and it helps to make the other treatments work better.” • Scratches or pastern dermatitis most commonly affects one or both hind limbs with varying levels of pain and itchiness. The condition initially shows up as erythema (dew poisoning), swelling and scaling on the pastern, then progresses to discharge, matting of hair and crusting. Veterinarians usually diagnose this problem when there’s abrasive mud in corrals, or when ice crystals are mixed in the snow and dirt. “We think the moisture content has something to do with it: something seems to set up the right environmental conditions to induce scratches, particularly in the spring,” says Ashburner, adding that the condition usually shows up on a white leg. “It responds very well if treated early, but it’s often missed by the owners until the horse’s pastern is very sore or very swollen. And the longer they have it, the harder it is to treat.” Severe cases of scratches can also lead to a longstanding, immune-mediated infection called vasculitis that can take months to cure. If diagnosed early, the ideal treatment is to clean the area very well with mild soap (no abrasive cleaners) then remove as much of the scabby debris as possible. Clipping the hair can help to remove the scabs. “We keep the area dry and use a topical cream — a combination of antibiotic and steroid cream — to fight the mixed infection,” explains Ashburner. Clark adds that it’s important for veterinarians to be aware that scratches isn’t “one specific disease with one specific cause.” If certain horses or horse herds continue to be plagued by this type of dermatitis, practitioners need to look at the animals’ environment, their habits and what they’re used for to learn more about probable causes. • Rain scald (dermatophilosis) is a bacterial skin infection that causes superficial, pustular and crusting dermatitis in horses. These lesions are most commonly found on horses’ rumps, saddle area, face and neck — or on pasterns, coronets and heels (in the form of scratches). The two most important factors that lead to rain scald are skin damage and moisture. The condition is often diagnosed in horses after intense rain, and when temperatures and humidity are high. Veterinarians on the Prairies don’t often see rain rot, but it’s a common problem in B.C. While most cases of rain rot go away within a month, the best treatments include keeping the animal dry, removing crusts, and using topical treatments and using systemic therapy if the infection is chronic or severe. • Melanomas are malignant skin tumours that are most commonly — but not exclusively — found in grey or white horses over six years of age. Arabians, Percherons and Lippizaners commonly develop these tumours that are often found on the undersurface of the tail and the perianal region. Tumours can also be found on the lips, base of the ear, on the legs, or anywhere else on the horse’s body. The melanomas are usually firm, nodular to plaque-like, and they may or may not be alopecic (hair loss), hyperpigmented or ulcerated. Veterinarians can use surgical excision or cryotherapy to remove solitary tumours, but in most cases, the tumours require no treatment. • Insect hypersensitivity: Western Canadian horse owners and veterinarians deal with fewer parasitic problems than in other parts of the world because of the region’s cooler climate, but insect hypersensitivity is still a common problem in the spring and summer months. Controlling insects and using anti-itching agents can help to manage insect hypersensitivity. The use of ivermectin, moxidectin and other dewormers has also helped to reduce the occurrence of conditions like sweet itch, says Ashburner. - Sweet itch or Summer Seasonal Recurrent Dermatitis (SSRD): The most important cause of equine insect hypersensitivity is Culicoides gnats (sandflies, no-see-ums, biting midges). Affected horses develop itchy, crusted papules on the top of their tails, along their mane, neck, withers, hips, ears and forehead. The disease’s itchy nature causes horses to scratch and chew at themselves, or they may rub against stalls or fences. That can lead to hair loss, ulcer development and damage to the animals’ manes and tails. - Mange is caused by mite infestations in horses’ coats. Owners and veterinarians usually see these infestations during the late winter and early spring, and contributing factors include crowding, prolonged stabling, and poor nutrition. - Lice infestations are commonly found in horses during the winter when the animals’ coats are longer and they may be in close contact with their herd mates. Biting lice are usually found on the horses’ dorsolateral trunk, while sucking lice prefer the animals’ mane, tail and fetlocks. Clinical signs include scaling, a dishevelled coat, hair loss and mild to moderate itchiness. Reprinted with permission of Horse Health Lines, news publication for the Western College of Veterinary Medicine's Equine Health Research Fund. Sign up for the Horse Health Lines e-newsletter at www.ehrf.usask.ca
February 3, 2011 08:14
Horses are living long lives on acreages, farms and ranches across North America. That reality is reflected in statistics: it’s estimated that geriatric horses (animals more than 20 years old) account for somewhere between seven and 20 per cent of the entire equine population.
Owners and veterinarians are growing more aware that proper management and medical care can expand the lifespan of these horses. Many age-related issues like dental disease or parasite problems can also be prevented through regular veterinary care that’s provided throughout a horse’s life.
Dr. Katharina Lohmann is an internal medicine specialist and an associate professor in the Western College of Veterinary Medicine’s Department of Large Animal Clinical Sciences. Since many of her regular patients at the College’s Veterinary Teaching Hospital are equine senior citizens, Lohmann has gathered together a wealth of health management tips that are specific for geriatric horses.
The following story is an abridged version of a comprehensive article that Lohmann wrote for a national veterinary publication called Large Animal Veterinary Rounds that’s written at the WCVM. Visit www.canadianveterinarians.net/larounds (click on “Archives” for the complete title list) to read the entire article that was published in June 2007. Plus, make sure to read another helpful article called “Diseases Affecting the Geriatric Horse” (published in September 2007).
FOOD AND WATER
A common challenge in caring for older horses is maintaining their weight. Several factors can cause a horse to lose pounds or adequate body condition: underfeeding, protein-calorie malnutrition, nutrient loss, the inability to eat, a lack of appetite, or a physiologic condition or illness.
In many cases, it’s not enough to simply increase the amount of feed: it may take some research to understand the root of the problem. For example, if an older horse is underfed with protein-calorie malnutrition, the animal may have trouble eating the existing feed. In that case, you may need to find an alternate feed that’s easier for the horse to chew or digest. Or, if younger herdmates are preventing the senior horse from getting enough access to food, you may need to rearrange the herd and provide more accessible feed sources to avoid competition.
Q. How much fuel does a senior need?
An older horse’s feeding regimen generally needs little or no adjustments as long as the animal maintains its weight and body condition. The National Research Council’s (NRC) energy recommendations for adult horses equates to about 7.5 to 11 kilograms of hay per day — depending on feed quality and energy content. However, these ration estimates are only a starting point and need adjusting to account for exercising, chronic illness or conditions, or cold weather.
Use body conditioning scoring systems or weight tapes to monitor an older horse’s body condition. While weight loss is a common concern, you also need to be sure that obesity doesn’t become a problem.
Q. What are the best energy sources?
While good quality forage is the ideal maintenance feed source, older animals with dental issues may need alternate feed to maintain body condition. Complete pelleted feeds meet all dietary requirements for senior horses including higher protein and fat content along with balanced mineral supplementation. If a horse doesn’t have a condition like recurrent choke, you can also feed supplemental hay to satisfy your horses’ chewing needs and to prevent boredom or bad vices.
Make the switch from hay to pellets gradually, and adjust feed amounts for the individual horse. As well, consider cost before deciding to make the switch: based on maintenance requirements, a horse will need about 15 to 20 pounds of complete feed per day.
One cheaper alternative: feed energy-packed beet pulp and grains or sweet feeds to senior horses along with their daily hay ration. But these high-carbohydrate diets aren’t recommended if a horse has chronic laminitis or insulin resistance (a common condition associated with pituitary dysfunction).
While supplemental feeds with higher fat content are available in feed stores, you can also add vegetable oils to your animals’ diets. You can feed up to two cups of oil to an average-sized horse in two or more daily feedings with small amounts of beet pulp and grain, but start with smaller volumes and gradually increase to oil amounts over two to three weeks.
Q. What are changes in digestive capacity?
The energy requirements of older horses may not change, but their ability to digest certain nutrients may be reduced. Geriatric horses may prefer feeds with higher protein concentrations with less fibre content, and it may also be advisable to increase mineral supplementation so the horse gets enough phosphorus. But be careful about making these kinds of changes if horses have been diagnosed with renal or liver disease.
Since chronic parasitism can cause decreased feed digestibility in older horses, it’s important to maintain a good deworming program. If a horse has trouble maintaining its body condition, use extruded feeds or add Brewer’s yeast that has the added benefit of providing supplemental B-vitamins.
Q. What are changes in water intake?
Dental pain or decreased thirst perception may cause older horses to reduce their water intake. That can cause low-grade chronic dehydration that leads to reduced exercise tolerance and a predisposition to impaction colic or renal dysfunction. As well, older horses can develop choke if they don’t drink enough water along with alfalfa pellets or other pelleted diets.
How can you increase your horses’ water intake? One option is to soak their hay or roughage, but that’s not a long-term solution since it reduces the feed’s nutrient content. Adding salt to a horse’s diet may increase thirst, but animals must have free access to water and it’s advisable to test for adequate renal function before using this option. Another suggestion: feed mashes or slurries to geriatric horses — a good way to ensure that they ingest some fluids.
If horses aren’t drinking as much because of oral pain, it’s important to correct the dental problem. Heated water sources will also help to reduce the pain of cold water on a sensitive mouth. If an older horse has a chronic condition like laminitis, it’s also important to make it as easy as possible to give the animal ready access to clean water.
Regular exercise can improve a horse’s mobility and slow down the effects of age on cardiopulmonary and musculoskeletal function, but exercise regimens should be tailored to the horse. As well, be aware that older horses may be prone to overheating during strenuous exercise and may become dehydrated. As the horse’s body changes, it may also be necessary to adjust the animal’s regular saddle and tack.
Common causes of reduced athletic capacity in older horses include: • musculoskeletal problems that are caused by the cumulative “wear and tear” of athletic activities versus acute conditions.
• decreased range of joint motion that can lead to further lameness problems if a horse tries to perform strenuous exercise.
• age-related changes in body conformation such as swayback.
Some musculoskeletal conditions in older horses can’t be cured. Instead, they require long-term management and pain control through the use of non-steroidal anti-inflammatory drugs (NSAIDs) or other systemic medications, supplements (such as glucosamine or hyaluronic acid) or arthrodesis of low-motion joints. Specialized trimming and shoeing can also be helpful in managing musculoskeletal issues.
PREVENTIVE CARE AND VACCINATIONS
Geriatric horses may be more susceptible to infections based on declining immune responses with age, concurrent diseases, general debilitation and poor nutritional status. Researchers have demonstrated that declining immune responses with age primarily affect the adaptive immune responses, specifically antibody formation, while the innate immune system remains relatively stable throughout life.
Here are some recommendations about vaccination practices with older horses:
• routine vaccination against viral diseases like influenza should continue throughout life.
• continue vaccinating against life-threatening conditions like encephalomyelitis, tetanus and rabies. In contrast, some scientists recommend that owners discontinue vaccination against equine herpes virus infection since it may provide little benefit and may favour reactivation of latent infections.
• inactivated vaccines are thought to be safer for geriatric horses compared with attenuated live vaccines.
• optimizing a horse’s overall health status can help to achieve the maximum benefit of vaccination.
Since chronic parasitism is a common problem in geriatric horses, review your deworming strategies — especially in animals with a perceived loss of body weight and/or condition, or with pituitary dysfunction. Monitor parasite load in an older horse through regular examinations of body weight, body condition and fecal egg counts.
Lohmann, Katharina L. “Management and Care of the Geriatric Horse.” Large Animal Veterinary Rounds 7(5), 1-6. Reprinted with permission of Horse Health Lines, publication for the Western College of Veterinary Medicine’s Equine Health Research Fund. Visit www.ehrf.usask.ca to sign up for a free e-newlsetter.
January 25, 2011 09:14
Shirley and Jack Brodsky have bred and raised registered Paints on their 160-acre farm near Saskatoon, Sask., for nearly 20 years. That experience “in the field” has taught Shirley some valuable lessons about raising and caring for a large herd of multi-aged horses throughout the changing seasons.
In the spring of 2009, Shirley took time out of her busy schedule to answer some questions about caring for older horses and about her feeding routines when temperatures drop. To read the article about Shirley’s 25-year-old broodmare Double Value (Val) and geriatric horse care, visit the Summer 2009 issue of Horse Health Lines.
Q. What’s your winter feeding regime for your horse herd?
With all of my horses, I try to follow what would be natural for them as closely as possible. I try to make sure the broodmares don’t get terribly fat: I don’t like to over-supplement them. They’re on unlimited hay all winter, and they run on an 80-acre pasture where they have shelter from the wind. They get salt, water, a supplement block every two weeks, and I sometimes feed them a little grain (whole oats) — but not all of the time. That’s about it. It’s not very fancy.
Q. How do you water your horses?
They have access to a heated water bowl all winter, and I feed them far from their water source so they have to come in to drink. That keeps the whole group active, and I think it’s good for digestion and social order. They definitely have a set pattern, and it’s the older mares that will decide when they go for water. They’ll bring in the whole herd for water and after they get their fill, they’ll linger for awhile. But if it’s windy, they’ll head back to the trees for shelter.
Q. What kind of shelter does your herd have during stormy winter weather?
I build a lot of wind shelters with large round straw bales. If the horses can get out of the wind and have lots to eat, they seem to do well — even during storms. I never blanket my horses: I don’t want to affect their winter hair coats. But if a horse’s hair coat isn’t thick enough for the weather, I might have to consider it.
Q. How do you prepare your horses for the winter?
One thing I’ve learned from watching my herd is that all of the horses really want to load up on food in the fall. I think they’re instinctively trying to prepare for the winter by laying down a layer of fat before it gets too cold. I really try to ensure that the horses have all they can eat in the fall, because I hate to see older horses go into the winter on the thin side — they’re always behind and trying to catch up on their weight gain.
Once the pastures start to burn off or if it’s dry, I’ll start hauling in hay. Depending on the weather, I may start feeding hay to the herd as early as August. For the first few bales, the horses eat as if they’ll never be fed again — but then they calm down when they realize that I’ll be bringing more.
Again, I like to make the feeding transition easy so there are no health issues. The fall is often when colic cases occur because once the temperature drops, owners dump out large quantities of hay and their horses eat too much — leading to impaction.
Q. What kind of hay do you feed to your horses?
I feed them a mix of alfalfa, brome grass and a larger percentage of crested wheat. The hay is in large round bales that I unroll on the ground instead of putting them in round feeders. By doing that, I find that we don’t get as many respiratory problems plus we don’t get one or two dominant horses guarding the whole bale from others in the herd. The hay also tends to mix with the snow and take on some additional moisture. Plus, it allows the horses to eat more naturally — closer to how they regularly graze.
The quantity really depends on the type of winter we’re having. The growing horses — the coming yearlings and two years olds — will eat as much as the pregnant mares. If it’s a long, cold winter, the herd will eat three times as much as they do during a mild winter. I always think of it being like stoking a furnace – you just keep throwing it in there.
We try to give the horses the best quality hay that we can. Our hay is custom cut on our land, so our quality depends on the haying season from year to year. Sometimes, the weather doesn’t allow us to cut it when it’s ready and we end up with less than optimum hay. If the hay is marginal, I tend to supplement it with more grain.
But truthfully, I think the horses do better on just plain old grass hay that may be more coarse. If they eat second-cut alfalfa — the rich, “dessert” type of hay — it just seems to go through them without producing much energy.
Q. The winter of 2008 was long and hard on some horses. What did you do to keep your herd healthy?
Toward the end of last winter, I started hauling oats out to the horses. I could tell that the older mares were feeling it because the cold went on so long. When we get in that situation, I do like to supplement them with grain plus beet pulp and some canola or corn oil — those are my favourite basic things. I soak the oats with beet pulp, oil and hot water: that just seems to give them a head start on digestion.
Q. Do you only supplement the older horses’ diet?
Everybody that runs together gets the same feed — young and old. When they have so much hair in the winter, it’s often hard to tell whether they’re losing weight, but I usually gauge it by the weather and their body score. After a few years, you get a sense of your animals’ condition and that’s the joy of having them around so long: you know when they’re doing well and you know when they’re not.
Q. How long do you feed hay to your horses in the spring?
It depends. For instance, since this spring’s (Spring 2009) pasture wasn’t very good because of all the cold, they were getting hay as well. I give them free-choice hay until the pastures were good enough and they left the hay. That way, we never seem to get any serious health issues when horses move from eating hay to fresh grass. We’ve had a little bit of colic but not very much considering the number of horses that we’ve had over the years. It’s worked so far.
Q. What about horses that do too well on feed: do you ever run into problems with horses carrying too much weight?
Not with the older mares, but I do have a few youngsters that are getting heavy. One mare in particular gets too heavy on spring grass, so I need to watch her weight.
If we are feeding grain to the herd, I feed them in a large circle instead of distributing the grain in a straight line or in corners. In this large of a herd, the dominant mare will push one and the whole circle will just continue to rotate. That helps to regulate how much feed each horse gets to eat.
Q. Do you still learn something new about your horses every year?
Oh, for sure. I’ve taken care of a herd for nearly 20 years, but I still feel pretty new at taking care of horses. I’ve worked closely with Dr. Sue Ashburner at the WCVM, and she got a lot of information for me from Dr. Frank Bristol — one of the WCVM’s retired professors who conducted equine behaviour research with large PMU (pregnant mares’ urine) herds. I also have different friends in the business who have been really good at answering my questions.
The one thing I learned is that you can’t be pigheaded about dealing with horses — you have to be flexible and you have to think like a horse. Every year, we get groups of veterinary students and veterinary technology students coming out here to learn more about horse handling and safety. I always tell them, “Drive out of town and just find yourself a big group of horses. Because you can learn so much just by watching a group of horses living together.”
Horses are herd animals that still operate on some really basic principles, and the problems start when we deviate away from that too much. I think we need to remind ourselves that we’re probably best to go back to what’s natural for them.
Reprinted with permission of Horse Health Lines, news publication for the Western College of Veterinary Medicine's Equine Health Research Fund. Sign up for the Horse Health Lines e-newsletter at www.ehrf.usask.ca.
December 23, 2010 21:25
The hair-raising atmosphere of a thoroughbred racing venue is thrilling for spectators and an accepted way of life for people whose livelihoods depend on the racing industry.
But what about stress levels of the highly trained animals at the centre of this multi-million dollar industry?
That’s a key concern for Dr. Fernando Marqués of the Western College of Veterinary Medicine’s Department of Large Animal Clinical Sciences. The clinical researcher recently completed a study confirming the high prevalence of nonglandular gastric ulcers, a potential source of stress, among Saskatchewan thoroughbred racehorses.
In a natural progression from his gastric ulcer study, Marqués has teamed up with large animal medicine resident Dr. Alberto Ruiz as well as Drs. David Janz, Bryan Macbeth and Marc Cattet of the WCVM. Supported by the College’s Equine Health Research Fund, the new project is designed to investigate the potential relationship between the presence and severity of gastric ulcers and the concentration of hair cortisol in thoroughbred racehorses.
After talking with Janz about his findings that link high hair cortisol concentrations to long-term stress in polar bears and caribou, Marqués decided to seize the opportunity to investigate cortisol concentrations in the animals he and his team were evaluating for gastric ulcers: “As we were endoscoping the horses, we pulled some hair from them and took serum samples so that we could analyze the cortisol levels afterwards.”
Ruiz, who took on the cortisol study as his Master of Veterinary Science (MVetSc) project, is now working on the analysis technique with Janz.
“Since the hair of polar bears and caribou and horses is very different and they come from very different environments, we’re trying to modify the technique to develop one that works for horses,” says Ruiz.
Using this customized cortisol enzyme immunoassay, the researchers plan to compare serum cortisol concentrations, indicators of short-term stress, to hair cortisol concentrations, indicators of long-term stress. Most importantly, they hope to establish a relationship between the cortisol levels and the presence and severity of gastric ulcers.
“If the cortisol increases with stress and if horses with severe gastric ulceration experience pain, then they may have higher cortisol levels than horses with no gastric lesions,” explains Ruiz. “Although we won’t be able to diagnose gastric ulceration just from the results, they may help us to identify horses that are more likely to have gastric ulcers.”
The researchers are hopeful that their study will eventually lead to an inexpensive screening test for cortisol concentrations that will be easily accessible to veterinarians and their clients. Using that information, owners could then make decisions about adjusting management techniques such as feeding frequency and training intensity.
Veterinarians could also greatly benefit from knowing which animals or groups of animals that are most likely affected with gastric lesions. A gastroscopy, the only reliable test for diagnosing gastric ulcers, is expensive and invasive. But cortisol measurements could be used to determine which animals may benefit from direct examination of the stomach. Plus, if a link is established between the cortisol levels and the severity of the lesions, veterinarians could use that information to determine a treatment protocol.
Ruiz points out that a screening device leading to early diagnosis of gastric lesions or ulcers could have a huge economic impact on the entire equine industry: “Gastric ulceration continues to be of great interest to horse owners and veterinarians. New studies are being published each year that are helping us understand the importance of treatment and prevention of gastric ulcers in horses. If we can discover ways to decrease diagnostic costs and improve on our ability to assess stress in horses, everyone should benefit.”
Reprinted with permission of Horse Health Lines, news publication for the Western College of Veterinary Medicine’s Equine Health Research Fund. Visit www.ehrf.usask.ca to sign up for Horse Health Lines’ e-newsletter.
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December 23, 2010 21:12
By Lynne Gunville
A study recently completed by WCVM researchers confirms that equine gastric ulcer syndrome (EGUS) is just as prevalent in Western Canada’s racehorse population as it is in other parts of the world.
By conducting gastroscopic examinations on thoroughbred racing horses stabled at Saskatoon’s Marquis Downs, the research team determined that ulcers in the nonglandular portion of the stomach were present in 74.5 per cent of the 94 racehorses involved in the study.
EGUS is a syndrome used to describe a number of clinical symptoms including ulcers or erosions in the esophagus, stomach and duodenum. In racehorses, this syndrome is characterized by inflammation and ulceration in the nonglandular portion of the stomach. Although the physiology is not completely understood yet, extensive research is being conducted into its control and diagnosis. Studies have indicated that management practices such as intensive training and intermittent feeding — both commonly used with racehorses — can increase the incidence of the condition.
WCVM’s research team, led by large animal internal medicine specialist Dr. Fernando Marqués, carried out their examinations during the 2008 and 2009 racing seasons at Marquis Downs. Although numerous world-wide studies had already confirmed that thoroughbred racehorses are most frequently affected by the syndrome, the researchers were curious to see how Saskatchewan horses would measure up.
“It’s the fact that we only race three months of the year and the horses are in pasture for the first part of the year,” explains Marqués. “But for some reason that doesn’t change anything about the prevalence, and those results are going to help us to do more about this population of horses.”
Using a portable video endoscope, Marqués and his team explored the presence or lack of lesions in the stomach and esophagus of the Saskatchewan racehorses. In order to establish possible risk factors, the team recorded a history for each animal that included gender, age, body condition score, racing performance for the last two months, level of training, history of medical and/or musculoskeletal diseases and treatments of each horse.
Based on the gastroscopic examination, each animal was evaluated from zero to four using a grading system established by the Equine Gastric Ulcer Council in which zero indicates an unaffected animal and grade four indicates the most severe grade of gastric ulcers. Of the 94 horses examined, 70 were found to have ulcers, with the majority of them being rated as grade two in severity. None of the risk factors proved to be significant
Marqués hopes that the study’s results will make local owners and trainers more mindful that EGUS may be affecting their horses. Since the clinical signs are vague and the animals don’t show any of the characteristic signs of pain such as rolling or sweating, people tend to assume that their animals are doing well even if they do have ulcers. But Marqués points out that these animals may have severe lesions in their stomachs.
“It’s an issue of awareness,” he explains. “You can inform people that their horse has a gastric ulcer, but they think the horse is happy, it’s racing, it’s performing fine, so they think they’re doing all right. But it makes a difference when you show people what the ulcer actually looks like.”
A follow-up study now being undertaken at WCVM will use the results of this research to help determine if there is a relationship between hair cortisol concentration and the presence and severity of the gastric ulcers found in the racehorses. The WCVM researchers are guided by previous studies involving wild animals that have already validated a technique for measuring hair cortisol levels and have established a link between the hair, the cortisol in the hair and the chronic stress of the animals.
Meanwhile Marqués and his research team, who have submitted the results of their gastric ulcer prevalence study for publication, are hopeful that their efforts will result in increased efforts to prevent and treat the condition among Saskatchewan’s thoroughbred racehorse population.
“It’s just common sense to me,” says Marqués. “If you can reduce those situations that cause discomfort in those horses and the horses are not in pain, then it makes sense that they will perform better.”
Lynne Gunville is a freelance writer and editor whose career includes 25 years of teaching English and communications to adults. She and her husband live at Candle Lake, Sask.
Reprinted with permission of Horse Health Lines, news publication for the Western College of Veterinary Medicine’s Equine Health Research Fund. Visit www.ehrf.usask.ca to sign up for Horse Health Lines’ e-newsletter.
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October 6, 2010 07:27
It was a conversation over coffee one morning that prompted a Western College of Veterinary Medicine research team to investigate the intestinal parasite load of horses living on the Prairies.
As Drs. Chris Clark and Steve Manning were discussing how often horses in the region should be dewormed, they realized that there was no solid scientific evidence to support their typical recommendations. “We’re borrowing recommendations from other parts of the world that may not be appropriate,” explains Clark. “The western Prairies need a western Prairie deworming program.”
Shortly after that conversation, Dr. Ela Misuno began her residency in large animal medicine at the College. Having worked in Denmark where dewormers are sold by prescription only, she was well aware of the growing problems resulting from parasites becoming resistant to deworming products.
Clark says that the timing was ideal: “Dr. Misuno joined us and had this interest and experience, so it was a perfect fit as her residency project.” Misuno, who has been instrumental in designing the project, will collect and test fecal samples for parasite load while Clark and Manning will co-ordinate the project.
The research team, which is funded by WCVM’s Equine Health Research Fund, also includes Dr. Lyall Petrie who has done extensive research looking at parasite burdens in sheep and cattle, including a study of how worm burdens in sheep change throughout the year. Dr. Emily Jenkins, a veterinary parasitologist from WCVM’s Department of Veterinary Microbiology, will make her laboratory available to Misuno and help interpret the data to determine whether or not the Prairie environment should influence deworming practices.
The researchers will identify approximately 20 mare-foal pairs from three local breeding farms and will follow them over a 12-month period. Clark explains that they included the foals in order to investigate parasites known to affect foals more than mares. They also want to determine whether foals are exposed to a high worm burden from their mothers — a condition known to occur in sheep.
Misuno will collect and analyze fecal samples for fecal egg count (FEC) every month through the summer, two to three times during the winter, and once again in the spring. Deworming with EqvalanÒ (ivermectin), which has been donated by Merial Canada, will occur only if testing reveals a high FEC, and a follow-up count will be undertaken a week later to ensure the treatment has been effective.
Farm owners will complete a detailed questionnaire providing information about their management practices. “There are so many variables like what is the previous deworming program, what’s the population density of the pasture and how dry or wet is the pasture — all of these things become quite complicated and that’s why we need this pilot study,” explains Clark. “We need to work out how to do this on a much bigger level.”
The researchers plan to use their results to design a larger study that will randomly select horses from individual farms and will provide veterinarians with the knowledge they need to advise horse owners on the most effective deworming practices for their region.
“People are prepared to spend money and maintain their horses in the maximum state of health,” says Clark. “We want to gather information so we can give people firm recommendations that will ensure the health of their animals.”
Clark emphasizes the importance of the initial project and says that veterinarians in the Prairie area will be given those results so they can start making recommendations that will enable horse owners to make informed decisions about their deworming protocol.
“There might be a real change in the way that people view deworming. We’ve always thought of just treating everything on the farm the same way. Maybe we have to start treating each horse individually: getting those fecal egg counts done and then deworming only the horses that need treatment.”
Clark points out that responsible deworming practices benefit everyone: “First of all, it will ensure that the horses have optimum health. Then if we can reduce the amount of money horse owners have to spend, that is obviously a benefit for them. And finally, if we use the drugs more effectively, there will be no resistance problems and the horses will stay healthy for years to come.”
Lynne Gunville is a freelance writer and editor whose career includes 25 years of teaching English and communications to adults. She and her husband live at Candle Lake, Sask.
Story reprinted with permission of Horse Health Lines, news publication for the Western College of Veterinary Medicine’s Equine Health Research Fund. Visit www.ehrf.usask.ca to sign up for Horse Health Lines’ e-newsletter.
September 30, 2010 13:29
Monensin: Fatal Feed
In a region where horses and cattle are often found in close company, it seems harmless for your horse to eat a handful of spilt cattle feed. But if the feed contains even small amounts of an additive called monensin, it could be a fatal mistake for your horse.
For most cattle ranchers and poultry producers, monensin (also known by its trade name, Rumensin
Ò) is part of the daily routine on their farms. Monensin has been used for years as a growth-enhancing feed additive for beef and dairy cattle and poultry in Canada and the United States. It also helps to control a parasitic disease called coccidiosis that primarily affects poultry and cattle to a lesser scale.
Cattle and poultry can ingest relatively high levels of monensin in their feed without any negative impact on their health. But for horses, it’s a different story.
“Cattle can tolerate 20 milligrams (mg) per kilogram (kg), body weight, of monensin in their feed rations without any problems whereas the toxic dose in horses is about 2.0 mg of monensin per kg, body weight. That’s about the same as a toxic dose of cyanide so it’s pretty toxic stuff,” explains veterinary toxicologist Dr. Barry Blakley.
“Any time a horse gets exposed to monensin, it’s a problem.”
A familiar poison
Blakley, whose toxicology laboratory in Prairie Diagnostic Services at the Western College of Veterinary Medicine (WCVM) serves all four western provinces, usually receives calls about monensin poisonings in horses at least once or twice a month.
“Obviously some veterinarians don’t call: they just go ahead and treat the case as they see fit. So there are probably a lot more cases of monensin poisoning that we just don’t hear about.”
Monensin is an ionophore — a chemical that affects the transport of ions in the various cell membranes. This ability makes monensin capable of controlling the parasite coccidia in chickens and other animals, but it also makes it deadly for horses. While it does affect many systems, its main impact is on the animal’s muscles — especially the heart.
In a healthy horse, natural ion fluxes of sodium and potassium allow for the contractility of the heart. Monensin disrupts those ion fluxes, causing the horse’s heart to work improperly and leading to eventual cardiovascular collapse.
Why is monensin so toxic to horses in comparison to other livestock? Scientists still don’t know the exact reason, but the feed industry has been aware of monensin’s devastating effect on horses since it was first introduced as a feed additive in the mid-1970s.
While it’s illegal to mix monensin in any horse rations, Blakley says accidental poisonings occur when there’s a mixing error at a feed mill. “In these cases, we usually ask, ‘What feed did you mix right before producing horse feed?’ If the plant made cattle or poultry ration just before switching to horse feed, we immediately know what must have happened.”
Overall, only a small percentage of monensin poisoning cases are caused by contaminated horse feed. The more common scenario is a horse accidentally eating cattle feed containing the additive. For example, Blakley says monensin poisonings have occurred most commonly at beef cattle feedlots where working horses may be exposed to spilled cattle feed by accident.
Symptoms: straight to the heart
The symptoms of toxicity vary with the amount of monensin ingested by a horse. Trace amounts may cause a horse to go off his regular feed, show signs of colic and appear unwell for a few days. Larger amounts will cause a horse to show more serious symptoms within a few hours including colic, stiffness, sweating, a lack of co-ordination and the inability to stand.
As Blakley points out, these symptoms are non-specific — making it difficult for veterinarians and horse owners to confirm the problem. Ultimately, examining a horse’s cardiovascular system provides the most important clinical evidence: an affected horse’s heart rate may double or triple, and its breathing will be laboured even though it’s standing still.
“In horses, the most important and obvious result of monensin poisoning is damage to heart muscle. Sometimes animals die very quickly with acute, congestive heart failure. In other cases, horses may die of heart failure in a few days or even weeks later.”
To confirm a diagnosis of monensin poisoning, Blakley says veterinarians and toxicologists rely on blood and urine samples that provide two key pieces of information. First, an affected horse’s blood will contain dramatically elevated muscle enzyme levels. Second, a horse suffering from monensin toxicity will have high levels of the muscle protein myoglobin in its urine. Both are indicators of muscle damage.
In a more prolonged situation where the horse doesn’t die in the first few hours, echocardiography (ultrasound examination of the heart) may provide direct evidence of cardiac dysfunction. Death of cardiac muscle, congestion of the lungs and swelling of the liver may also be apparent in a post mortem examination. Since monensin causes membrane damage, Blakley says there may be no obvious lesions or signs that make a simple or obvious diagnosis for pathologists.
What’s also challenging about monensin is that it’s a molecule that breaks down very quickly, making it very difficult to detect — especially in cases where the affected horse lives for several days. As well, very few toxicology laboratories have established the methods for monensin detection. Tissue samples in Western Canada are often submitted to one of several government laboratories for analysis.
Blakley says a quicker alternative is to test the affected horse’s feed — something that’s done by the Canadian Food Inspection Agency (CFIA) as part of its mandate to monitor feed-related problems in the country.
Damaged for life
Although there’s no antidote for monensin poisoning, Blakley says some practitioners have used selenium and vitamin E to stabilize muscle membranes in acute cases. This approach has limited success, mainly because the muscle membranes are already damaged by the time there’s a confirmed diagnosis.
“It may minimize the damage, but it doesn’t eliminate it.”
And that’s the heartbreaking part about cases of monensin toxicity. Even if a horse does recover, the damage to muscles — including the heart — is permanent and may have consequences later in life. Surviving horses may, at some later date, develop signs of congestive heart failure if they are ridden, used in some type of performance sport or stressed in some other way.
“Recovered horses may look okay and appear to be in good health. The big concern is that an affected horse could become ill while someone is riding or driving it,” says Blakley.
Another concern is the sale of monensin-affected horses: owners must be upfront and disclose that a horse has suffered monensin poisoning so that the new owners are forewarned of potential long term effects on the heart.
In Western Canada, Blakley has been an expert witness in several cases where new horse owners have taken former owners to court because they believe a purchased horse suffered from the effects of monensin poisoning. Months or even years after a potential poisoning, Blakley says it’s very difficult to prove that a horse has ingested the drug.
“If a horse dies and a post-mortem examination is conducted, the pathologist may find evidence of heart muscle damage — but that’s about it. The fact that the drug disappears from the tissues very quickly makes it very challenging to prove that they have been exposed to monensin. All you know is that you’ve got a horse with a heart problem.”
What Blakley hopes is that increased public awareness of monensin and its deadly effects on horses will make owners more vigilant about keeping livestock feed separate and to not assume that what’s good for cattle and poultry must be good for horses.
“Some farms keep horses with cattle and having the animals eat the same feed isn’t unusual. If you’re going to do that, make sure there’s no monensin in the feed.”
ADDING MORE FACTS ABOUT MONENSIN
• Monensin is an ionophorous antibiotic produced by the fungus Streptomyces cinnamonensis. An ionophore is an organic compound that affects the transport of ions across cell membranes.
• In the poultry industry, monensin is used to prevent a parasitic infection called coccidiosis and is sold under the trade name Coban 60Ò .
• Monensin is also known as RumensinÒ, a growth promotant in cattle and poultry that’s added to premix, pelleted or bulk feeds, and mineral blocks. It improves feed efficiency, the rate of gain in cattle and reduces the incidence of feedlot bloat and acidosis.
• Horses are particularly susceptible to monensin toxicity: the median lethal dose is only 2.0 to 3.0 mg/kg. Reports of monensin poisoning in horses have appeared since 1975. One example occurred in 1986 when several hundred horses in Michigan were exposed to varying levels of monensin after an Ontario feed mill made a feed substitution error.
• It’s believed that in horses, the drug inhibits sodium and potassium ion transport across cell membranes. This leads to mitochondrial failure (the parts of the cells that are responsible for energy production) and other physiologic issues.
• While horses appear to be the most sensitive to monensin, the drug is also toxic to other animals when given at higher doses than recommended, when mixed with incompatible drugs, or when feed rations are accidentally given to animals for which they’re not intended.
• The median lethal dose of monensin varies for different species: 12 mg/kg for sheep; 16 mg/kg for pigs; 20 mg/kg for dogs and 200 mg/kg for chickens. Cattle fed five to 10 times the recommended doses of monensin can also be poisoned. The median lethal dose in cattle is 22 mg/kg — more than 20 times the recommended daily dose.
Reprinted with permission of Horse Health Lines, news publication for the Western College of Veterinary Medicine's Equine Health Research Fund. Sign up for the Horse Health Lines e-newsletter at www.ehrf.usask.ca