Follow Up On Iceland Outbreak
The massive outbreak of infectious upper respiratory tract disease that hit Iceland four months ago is finally slowing down, and there is now a little more information available about what they've been seeing and what authorities believe has been going on.
There is a fairly clear description of the clinical signs seen in affected horses (as previously described), although signs vary from horse to horse. Typically illness begins with a serous (clear) nasal discharge which then becomes mucopurulent (snotty). There is sometimes mild conjunctivitis (e.g. red puffy eyes) and most commonly a dry cough. Horses that are examined using endoscopy show signs of laryngitis. Signs generally last 4-6 weeks, but this can vary.
There's also more information about the epidemiology of the disease (i.e. the pattern of spread). Morbidity seems to be close to 100%, meaning almost every horse that is exposed gets sick. Fortunately no mortality has been associated with the disease, meaning all the horses eventually recover. The incubation period (the time from exposure to illness) is 1-4 weeks. It seems to be spread mostly by direct contact, but indirect transmission is also possible, as even free-roaming herds with little contact with other horses or people have been affected. Horses are not completely immune after recovering (meaning they can get sick again if they are re-exposed), but there is evidence that the "herd immunity" of the horse population in Iceland is increasing, and the outbreak seems to be dissipating. It is still lingering in some horse groups where there are naive (unexposed) horses coming into contact with infected horses.
The way this disease has spread is very typical of a virus burning through a naive population which has never been previously exposed to or vaccinated against the disease. Even the clinical signs are very typical of an upper respiratory virus. However, extensive testing has been done using both PCR and antibody titres for a multitude of viruses including (but not limited to): equine herpesviruses 1, 2, 4 and 5, equine arteritis virus, equine influenza virus, equine reoviruses, and equine rhinitis viruses. None of these viruses appear to be the culprit, despite early suspicions that the cause was in fact equine herpesvirus. They are still testing for new/unknown viruses using viral culture, but this is a difficult and very time-consuming task.
What authorities have been able to find in affected horses is Streptococcus equi subsp. zooepidemicus, which is what is currently being blamed for the outbreak. They say it has been cultured from almost all coughing horses and all horses with mucopurulent nasal discharge. But that's not really surprising, as S. zooepidemicus is a very common commensal bacterium that is even carried by healthy horses in their upper respiratory tracts. It's also a very common opportunistic pathogen in horses, meaning when the animal gets sick for another reason (for example, if a horse is infected with a respiratory virus), then S. zooepidemicus moves in and causes a secondary bacterial infection, which can make the clinical signs worse or last longer, and may lead to other complications. In this case they are trying to make S. zooepidemicus out to be the primary pathogen, but it would have to be a very unusual strain of the bacterium - very virulent, highly infectious and totally novel to the horse population in Iceland - to cause an outbreak of this scale. They are doing additional testing to characterize the strain they have isolated from infected horses and to compare it to other strains previously isolated from horses in Iceland.
The good news is that after the horse industry in Iceland was paralyzed by this outbreak for almost four months, equestrian activities are now resuming under the supervision of the Icelandic Food and Veterinary Authority. That shouldn't pose a problem to the Icelandic horses, as there are very few naive horses left in the country that would still be highly susceptible to this still somewhat mysterious disease. However, export of horses from Iceland is slated to recommence on September 15. There are still quarantine requirements preceding export (horses must not be sick nor be in contact with a sick horse for 30-60 days prior, depending on what country they're going to), which always are and will remain very important for infectious disease control. However, with the cause of the outbreak still being somewhat unclear, it is unknown if any horses may now be healthy carriers of the outbreak pathogen, be it an unusual strain of S. zooepidemicus or an unidentified virus. If horses in other countries start getting sick a few weeks after exposure to exported Icelandic horses, strict control measures will have to be rapidly implemented to possibly prevent similar outbreaks from developing.
Photo credit: David Blaikie (source: http://commons.wikimedia.org)
Following a repeating trend that has been ongoing over the past couple of years, piroplasmosis has been identified in more US horses with no clear source. 
While it seems straightforward, disinfection is pretty easy to screw up. It's not uncommon for me to find illogical or completely ineffective "disinfection" practices when I do farm investigations. In general, people don't really understand much about disinfectants and disinfection. That's not too surprising because it's not exactly a common or enthralling topic (and I didn't really know much about it until I became focused on infection control).
Salmonella is the bane of existence of equine hospitals. It's the most common cause of infectious disease outbreaks, some of which can be devastating.
The Royal Canadian Mounted Police's famed Musical Ride has been hit with strangles
Despite initial declarations that known common causes had been ruled out, the investigation into the 
The rather 
Methicillin-resistant Staphylococcus aureus (MRSA) is a huge problem in people and is an emerging pathogen in horses. Most earlier reports of MRSA in horses involved one strain, called CMRSA-5 in Canada, USA500 in the US, and sequence type 8 (ST8) as a more general term. This human-origin strain seems to be adapted for survival in horses, and in North America, this strain has accounted for most MRSA infections in horses and MRSA infections in people linked to horse contact.
While the manufacturer doesn't seem to be providing much information, Dr. Carolyn Cooper from the 
Strangles outbreaks are a pain. They can result in infection of a large number of horses and major hassles. Unfortunately, while many people behave properly during outbreaks, there are also people out there who either don't think, don't listen or don't care (or don't do any of these). 
Strangles continues to be a hot topic in southwestern Ontario. Whether it's really because of increased numbers of cases this year or just more talk (especially on the internet) isn't clear, but there are many questions, concerns and misconceptions regarding this disease and Streptococcus equi, the bacterium that causes it.
Infectious disease outbreaks in barns get a lot of attention, and none of it's good. Unfortunately, the same degree of attention is rarely given to measures used to reduce the risk of infectious diseases. Infectious diseases are an inherent risk of horse ownership, but there are a lot of things that we can do better to help reduce the risks. Developing a good infection control plan is one thing. Enforcing it is another. The best laid infection control plans are often rendered useless because people don't comply with them. This is a particular problem in some boarding stables that have multiple different horse owners with different ideas, perceptions, veterinarians and willingness to cooperate. One way to help improve infection control in these situations is a good boarding contract. Why? Because a boarding contact can lay out exactly what is expected from everyone up front, and the repercussions that can occur if someone (barn owner or horse owner) doesn't do what is expected. Infection control responsibilities should be built into every boarding contract. This helps improve infection control by laying the foundation for application of good infection control practices. There are several infection control topics that should be addressed in boarding contracts. Some things to consider include:
Few things get the horse rumour mill going like strangles. This infectious disease carries such a stigma that the simple act of having a sick horse (or even the suggestion that someone has a sick horse) can lead to rumours that spread like wildfire, along with complaints, accusations and other generally antisocial behaviour. Currently, depending on what rumours you listen to, there are either major strangles outbreaks going on in multiple large facilities across Ontario, or everyone is fine and there are no sick horses of any type in the province. (Like most things, the truth probably lies somewhere in between.)
. Stop focusing on the wrong things
It's common for people to wipe injection sites in horses with alcohol before inserting the needle. It's so ingrained into some peoples' minds that they may complain if their veterinarian doesn't use an alcohol wipe before injecting. But what does that little swab really do, and is it needed?
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Often, when someone calls and asks about management of strangles, one of the first questions is 
A three-year-old Standardbred gelding was presented to the hospital for evaluation and treatment of diarrhea (colitis). The previous week the horse had developed a mild hind-limb lameness which seemed to come and go, and it was decided to treat the horse with antibiotics “just in case” it had something to do with an infection. The horse was treated with ceftiofur (an antibiotic, often sold under the brand name Excenel or Naxcel) for five days. On the fifth day, the gelding developed moderate to severe diarrhea. The next morning the horse also had a fever. He was treated with anti-inflammatories and quickly referred to the hospital for intensive care.
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As foaling season approaches, it's a good idea for people to review proper umbilical care. The umbilicus is an important route of infection in foals, and can be associated with problems including local umbilical abscesses, large abdominal abscesses extending to the liver, and overwhelming body-wide infection (sepsis). The reason the umbilicus is such a critical structure is that it contains three major blood vessels (two arteries and one large vein) and the urachus (which connects the umbilical cord to the foal's bladder) . When the umbilicus ruptures shortly after birth, these structures are exposed to the bacteria-laden environment of the outside world and can be a route of entry for local and deep infections. Care of the umbilicus during the initial high-risk period is a key part of raising a healthy foal.
An eight-year-old Quarter Horse gelding was presented for examination due to chronic weight loss over several months. Lately he’d also been lying down frequently and exhibiting increased breathing effort, so he was treated for what was suspected to be mild signs of colic, but failed to improve. He’d also collapsed once during mild exercise.
Rotavirus is an important cause of diarrhea in young horses. (It's also a major cause of diarrhea in infants, but a 
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Following on the heels of a few outbreaks of piroplasmosis in the US over the past year is .gif)
Equine Piroplasmosis Disease Investigation Continues.jpg)
At the recent symposium of the 
A five-year-old Quarter Horse mare was found down in the field in the mid-afternoon. The horse was seen moving around the field normally less than eight hours earlier. She was found near a fence, but there were no external signs of trauma on the mare's body. Some green feed material was present at the nostrils. With encouragement the mare was able to stand, but she was very unsteady and uncoordinated, particularly in the hind limbs. Upon examination by the veterinarian in the field, it was also noted that the horse could not open her mouth normally (lockjaw - which is often a sign of .jpg)
The ongoing large 
For a country that is "piroplasmosis-free," the US sure has a lot of piroplasmosis. The Texas Animal Health Commission has reported that this bloodborne disease, caused by Theileria equi, has been confirmed on a ranch in south Texas. The farm is quarantined and testing is under way to determine the scope of the problem. They are presumably also looking at ticks in the area to see if the types of ticks that are able to transmit the infection are present, and trying to figure out where the infection came from.
If you have a horse, sooner or later you have a horse with a gash somewhere on its body. Horses seem to have an uncanny ability to find the one sharp branch or protruding splinter of wood or nail in any paddock, pen or stall that no one else can ever find, no matter how hard you look. But in the end, horses, just like people, sometimes get cuts. Some cuts probably never even get noticed. Thankfully, a lot of them heal by themselves with no interference from us. In other cases, though, the cuts can get infected, and that's when you and your veterinarian need to step in and help that horse out.
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At the ongoing 
The recent 
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During a strangles outbreak, people often ask how (and when) they can say their farm is "strangles-free." They usually don't like the answer. Declaring a facility to be free of strangles, a highly contagious disease caused by the bacterium Streptococcus equi, is not cheap, easy or quick. It is, however, important.
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As a vet, I've been bitten by a wide range of animal species. When people talk about animal bites, they usually think about dogs and cats. Horses can (and do) bite as well. Most horse bites are probably playful nips that hurt a little yet don't cause major problems, but some bites can cause serious injuries and infections can result..jpg)
Horses sometimes need to be treated with antibiotics. That's an unavoidable fact. Some horses that are treated with antibiotics develop diarrhea, which can be fatal. That's another unavoidable fact. While those two situations can't be avoided, the risks can be decreased.
I often get asked "what's the best antibiotic?" The short answer (but the one people really don't want to hear) is "the one that works." It's obvious more complex than that, but, in reality, the best antibiotic to use for any given horse and any given disease IS the one that works, and the one that does so with minimal side effects, including both patient side effects (e.g. diarrhea) and microbial side effects (e.g. emergence of drug resistance)..jpg)
Hendra virus, as you've probably seen here and elsewhere, is back in the news as the cause of another outbreak in horses in Australia with subsequent transmission to people. This bat-borne disease is very rare but devastating, with high mortality rates in both horses and people. Currently, 
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A recent post about mandatory vaccination in show horses sparked a discussion about concerns regarding adverse reactions to vaccines. Dr. Carolyn Cooper of the 
Last year, there was a large equine influenza outbreak at the Crawford County Fair in Pennsylvania. In response to that, 
"Long-acting" penicillin, a combination of benzathine penicillin and procaine penicillin, is available for use in horses. The idea is that the drug releases penicillin slowly into the body so that a single injection lasts a few days. Good in theory - but not in reality.
Here's a question I received the other day:
Equine infectious anemia (EIA) is a rare disease but one that a lot of time, effort and money are put into avoiding. Most people know about this disease by way of the most common test (formerly) used to diagnose it: the Coggin's test (see image).
There is apparently still no evidence regarding the location of 
It was only a matter of time, but eastern equine encephalitis (EEE) has been found in more US states this year. EEE is an seasonally important disease in some areas, including Louisiana. More cases in more states, and perhaps even some regions of Canada, are likely over the course of the summer and fall.
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The horse population is perpetually at risk for major disease outbreaks. Sometimes we get lucky and nothing happens, sometimes we get regional outbreaks of disease, and rarely we see large national outbreaks (e.g. 
The 
There is still a great deal we don't know about C. piliforme and Tyzzer's disease. It is presumed that foals become infected by ingesting the bacterium from the manure of other horses or from the environment. No one knows how often foals are exposed to the bacterium in this way - it may happen to a lot of foals, but only a few of them get sick, or it may happen very uncommonly, but make most of the exposed foals sick. Tyzzer's disease occurs very suddenly and progresses incredibly fast. Affected foals are often simply found dead, even though they looked completely normal only hours earlier. If they are found alive, foals may be slightly to extremely weak and lethargic, and they may have a fever, diarrhea, and increased heart and respiratory rates. The gums and whites of the eyes may be yellowish (i.e. jaundice), which is sign of liver failure. Even if foals with Tyzzer's disease are found alive, their condition usually worsens very quickly and they often start having seizures before they die.
The latest issue of the 
Rhodococcus equi is a very well recognized pathogen in horses – it is a common cause of pneumonia in foals between the ages of 1-6 months, and infection is also sometimes associated with .jpg)
Rhodococcus equi is a common pathogen in foals between the ages of 1 and 6 months of age that is most infamous for its ability to cause pneumonia. Classic R. equi infection results in the formation of large abscesses throughout the lungs of young foals (see picture left), which can be especially difficult to treat because the bacteria are able to hide from the body’s immune system by living within white blood cells. However, this organism’s bag of tricks doesn’t end with lung abscesses – it can also travel to other parts of the body and cause all sorts of trouble. These kinds of infections may occur with or without the classic lung infection, and are referred to as extrapulmonary disorders (EPDs).
Diarrhea is a relatively common problem in foals. It can range from very mild to fatal, and sick foals can get worse (i.e. "crash") very fast. Outbreaks of diarrhea in foals can also occur. So while most cases of foal diarrhea are mild, the implications of this condition for both the foal and the farm can be huge.
At least 21 ponies belonging to a Venezuelan polo team died shortly before a competition yesterday in Florida. Not much information about what happened has been released. It was reported that the ponies exhibited 
Disinfection of stalls is an important infection control tool, especially stalls that have housed horses with potentially infectious diseases and stalls used for foaling. Unfortunately, proper disinfection of stalls is difficult even at the best of times, and is rarely achieved on most farms.
Here's a recap of West Nile virus activity in Canada in 2008.
April’s "bug of the month" is Streptococcus equi subspecies equi, the cause of equine strangles, specifically strain 4047. This is the first strangles strain to have its entire genome (i.e. all of its DNA, including every gene) sequenced. The March 2009 issue of the open-access journal 
The latest edition of 
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Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging problem in horses. Owners often ask if they should have their horses tested to see if they are MRSA carriers. There's no simple answer that applies to all farms, but basic points that need to be considered include:
In equine hospitals, intravenous (IV) catheters are often placed in the large jugular vein in the neck of horses to make it easier for everyone (the horse included) to give the animal fluids and/or medication. However. any time the body's normal barriers (e.g. the skin) are broken (e.g. by placing a catheter through the skin into a vein), there is an increased risk of infection. Catheter site complications can range from mild inflammation of the skin around the catheter, to serious infection causing thrombosis (blockage) of the vein and abscesses.
In a recent post on our sister site, 
The other day, I wrote about a few 
Infectious disease surveillance is an important part of the infection control program. 
West Nile vaccines are labeled to provide protection for 12 months. Before they can be marketed with such a label, these vaccines have to be tested to prove that they still offer some protection for the animal for at least that long. For some vaccines, like rabies, protection likely lasts much longer than the label claim, but until recently no one’s bothered to study most vaccines beyond one year. I have no doubt that the protective immunity does decrease with time – the protective effects of vaccine are likely highest (as Scott said) about 30 days post vaccination, and lowest at the end of the 12 months. But there is no evidence that the immunity drops off so fast that after 4-6 months the vaccine would require a booster to be adequately, if not maximally, effective. There are vaccines, like herpesvirus and influenza, for which we recommend boosters for horses semi-annually, but this is for animals that are at ongoing high-risk for exposure to these diseases, which are very common. Six months after mid-April is mid-October, and in this part of the world there are very few mosquitoes still flying around at that point.
As spring approaches (slowly... at least here in Ontario!), people once again start thinking about vaccination programs for their horses. A question that comes up every year is when is the best time to vaccinate against mosquito-borne diseases? Depending on your region, the pathogens of concern may include West Nile virus (WNV), as well as Eastern/Western or Venezuelan equine encephalitis virus (EEE, WEE and VEE, respectively). Often people get the generic response of "30 days before mosquito season," which isn't always very helpful.
Horses have a very different intestinal tract than people (and dogs and cats). A horse's intestinal tract is much likely to develop problems from antibiotic use, particularly antibiotic-associated diarrhea or colitis, which can be fatal. The root of the problem in these cases is disruption of the normal bacterial populations that live in the intestine (the microbial "flora"), which can allow harmful bacteria to multiply and spread. This can occur with antibiotics given by any route (even by injection), but using oral antibiotics can result in higher drug levels in the intestinal tract, which creates a greater chance of causing problems. The likelihood of a horse developing complications from any antibiotic is probably a combination of what bacteria the antibiotic kills and how much makes it to the intestinal tract..jpg)
I usually hesitate to write posts about strangles cases or outbreaks. I don't want to give the impression that these are unusual events, because strangles is not a rare disease, in terms of either single cases or outbreaks. When I post about an outbreak, it's usually because there's something particularly interesting about the outbreak or the report about it. Such is the case with 
Lawsonia intracellularis is an important cause of disease in weanling foals, causing a disease called proliferative enteropathy. Antibiotics, mainly erythromycin,are usually used as part of the treatment for this condition. However, little is known about the true antibiotic susceptibility of this bacterium. The problem is that Lawsonia does not grow in culture plates in a lab like most other bacteria with which we deal - it can only grow in cells, which makes it very difficult to test for antibiotic resistance. Antibiotic therapy for this disease is therefore chosen based on basic knowledge about the bacterium and anecdotal information about how animals respond to treatment. Obviously, this is not the ideal situation.
"A two-day horse show is different than an eight-day fair exhibition.'" Two days is lots of time to transmit infectious diseases.
Unlike dogs, which commonly have urinary tract disease, urinary tract infections (UTIs) are very uncommon in horses, but they can occur.
Infectious diseases are a major problem in young foals. Diseases, including diarrhea, pneumonia, meningitis, umbilical infections and joint infections can range from mild to rapidly fatal. Even in foals that survive the initial infection, these conditions can sometimes result in permanent problems. A study published in a recent edition of the 
An abscess is an accumulation of pus. Pus is basically dead bacteria, partly broken-down cellular debris, and white blood cells. Sometimes there can be a thick capsule of tough, fibrous tissue surrounding an abscess, particularly if it has been there for a long time (see picture left). Most abscesses occur as the result of a local infection that the body was able to contain (at least partly), but could not eliminate altogether, and that didn't "drain" naturally to an open space (e.g. outside the body). Over time, some abscesses may continue to grow and become quite large, which can cause many different problems depending on where the abscess is. "Sterile" abscesses can also occur, but are much less common - these lesions are not associated with a bacterial infection, but may occur following a severe trauma or in association with certain tumours..jpg)
As part of the 2008 Conference of the 
Equine piroplasmosis is a blood-borne disease that is caused by the parasites Babesia equi and Babesia caballi. Infected horses may develop mild disease characterized by weakness and loss of appetite. In more serious cases, horses may develop fever, anemia, jaundice (yellow gums and eyes), a swollen belly and respiratory problems. Other signs that are sometimes present include neurological abnormalities, red urine (secondary to destruction of red blood cells) and death. In contrast, many infected horses may no signs of illness whatsoever. Horses that recover may carry the parasite for a long period of time, and these horses can be a source of infection for other horses if there are ticks in the area capable of transmitting the parasite (not all species of ticks can transmit the disease). This can lead to the need for long quarantines. Horses that become persistent carriers of piroplasmosis need to be quarantined for life, euthanized or sent to a country where the disease is endemic.
Horses that most often become infected and sick from A. equuli are foals. This bacterium can cause a wide range of infections in these young animals, including septicemia (bloodstream infection), meningitis, pneumonia, omphalophlebitis (umbilical infection) and septic arthritis (joint infection). Foals can get infected from contact with other horses or even their own mares because the bacterium is so common. However, it typically only becomes a problem in foals that do not receive 
Diarrhea is a potentially life-threatening condition in horses. It's also frustrating from a diagnostic standpoint because, even with the most complete/comprehensive testing, a cause is only identified in a minority of cases. This is true for other species too, including people, and is a reflection of the complex nature of the intestinal tract and the numerous possible causes of intestinal disease. Diagnostic testing obviously costs money, so if it gives us an answer less than half the time anyway, it begs the question - why bother? Well, here are some points to consider:
I don't know whether Truro Raceway (in Nova Scotia, Canada) has bad luck, bad infection control or is just really open about any problems. Following an outbreak of strangles in December (
While it's a little early in the foaling season, it never hurts to think about vaccination plans for foals. Vaccination is an important part of the disease prevention program - but it's only one part... general 
I find it amazing that mammals can regulate their body temperature they way they do, despite drastic changes in the temperature of their environment. It was -30 degrees celcius this morning (welcome to Ontario in February!) as I was waiting with my daughters for the school bus, and despite the feeling that my ears were going to freeze and fall off, I'm sure my core body temperature was about the same as it was when I left the house. Body temperature regulation is a key function in mammals that is controlled by the central nervous system. The body expends a lot of energy and great effort to keep its temperature within quite a narrow range.
An accurate reading is critical. The thermometer used must be in good working order. New, digital thermometers are cheap and accurate, and usually the best option.
New animal health products are released on a daily basis. A great deal of time, effort and money is usually spent to market these products - sometimes more than was put into developing them. As a consumer, it's important to think before you buy, especially with new products. Take a moment to consider whether a product is right for your animal, and whether the product's intended use and claims are reasonable. The biggest problems tend to occur with "alternative" or non-traditional products, which encompass a huge range of products that are aggressively marketed, with little to no research or testing to back them up. Here are some specific points to think about:.jpg)
Streptococcus zooepidemicus (technically Streptococcus equi subspecies zooepidemicus), commonly called Strep zoo, is an important bacterium in equine medicine. It is one of the most common bacteria isolated from infections in horses. Like other streptococci, S. zooepidemicus is a Gram positive coccus, meaning that it stains purple with Gram stain and has a ball shape (coccus). Streptococci tend to stick together in chains (see picture right) which are often described as "string of pearls."
With foals, as with so many other things, one bad thing tends to lead to another. This is compounded by the fact that when neonatal animals start to "crash", they tend to crash fast. So in order to stop the vicious downward spiral before it's too late, it's important to recognize the early signs of things gone wrong and take appropriate action as soon as possible.
It's incredible how the vast majority of neonatal foals, perhaps especially those born in the cold mid-winter, are able to survive all the challenges they face the moment they hit the ground - clearing their lungs to take their first breath, learning to stand and suckle so they can get milk from the mare before their body reserves run out, suddenly being exposed to the elements and having to regulate their own body temperature, and a world of bacteria, viruses and other pathogens just waiting to take advantage of their unprepared immune system.
The investigation of the 
Until the outbreak investigation in the USA is complete and the disease is contained, use extreme caution or simply refrain from importing breeding animals, semen, embryos etc. from the USA.
Vaccine reactions are fairly uncommon and are usually mild, but some horses are prone to more severe reactions and it's often hard to decide what to do with them. Vaccinating them obviously poses some risk, be it short term discomfort or the potential for more serious problems. Not vaccinating also poses risks, if the horses are left more susceptible to infectious diseases. As the veterinarian in this case suggested, sometimes pre-treating the horse with an anti-inflammatory like Banamine (flunixin meglumine) can help reduce the risk or severity of some adverse reactions. However, even this doesn't work in all cases.
Potomac Horse Fever (PHF), a disease named for the 
I was reading a fact sheet on foal care today that was available online. It was one of those sources that gives a mixture of good, mediocre and bad information. One thing that I didn't like was a reference to tetanus antitoxin administration being a common practice in newborn foals. That might have been the case a couple of decades ago, but it is certainly not recommended now.
In December 2008, an outbreak of contagious equine metritis (CEM) was reported in Kentucky. The index case was a healthy stallion that underwent routine testing for exportation of semen and the causative agent, Taylorella equigenitalis, was isolated by cutlure on December 15. By the end of the month, three more stallions on the same farm were also identified as infected. At the moment, it is estimated that there are 28 horses in Kentucky and another 156 horses outside Kentucky that have been exposed. Another 250 horses are being traced across 27 states. The last outbreak of CEM in the USA was in 1979 in Missouri, although a few sporadic cases have been identified in the country in the last three decades. It is a reportable disease in both the USA and Canada, and there are strict import (and export) regulations for horses entering the USA and Canada from CEM-positive countries.
The potential PROS of molecular diagnostic testing include:
Ideally, the umbilicus should be inspected and treated within 30 minutes of foaling (see picture right: normal umbilicus 20 minutes post-foaling).
Most pharmaceutical products are dosed on the basis of weight (e.g. milligrams of drug per kilogram of body weight). That means an animal twice the size of another gets twice the dose.
The outbreak occurred at a racetrack in Zagreb. Not surprisingly, an H3N8 strain was responsible. Investigation of the cases determined that vaccine status had no influence on disease - both vaccinated and unvaccinated horses became equally sick. The vaccine used in Croatia at that time contained three influenza strains, including two different H3N8 strains, but the strains that were used were from 1963 and 1979. When they compared the strain that caused the outbreak and the vaccine strains, there were multiple genetic differences, which is not surprising given influenza's capacity to evolve over time. There were far fewer differences with the more recent strains used in vaccines in most other countries.
An outbreak of salmonellosis has killed at least 22 horses in Kjalarnes, Iceland
This post originally appeared on the 
That's all good news. In the bigger picture, though, was anything learned, and were any measures taken to reduce the risk of this happening again? A lot of this comes back to the debate about 
Lawsonia intracellularis is a bacterium that causes an intestinal disease called proliferative enteropathy in young horses. One of the reasons we still don't know a lot about this disease is that this bacterium can't be grown in a lab. One of the areas in which researchers are working to find more information is from where horses that become sick initially get Lawsonia... Is it from healthy horses that are carriers? Does it circulate in the horse population, or is there an outside source? Does it come from pigs (pigs can also be affected by disease due to Lawsonia infection)? Do other animal species such as wildlife carry it?
Equine infectious anemia (EIA) (aka "swamp fever") is a very important disease in horses, and can also affect donkeys and mules. This is the disease for which horses are given a Coggins test, which is required every six months for horses attending most shows and competitions, and for horses traveling internationally. EIA is caused by a retrovirus, more specifically a 
On December 9, the Infectious Diseases session was held at the 2008 .jpg)
Influenza vaccination is an important preventive strategy in people, and much effort is made to vaccinate as many people as possible with effective vaccines. Every year, the 
One horse owner stated "If I had known it was out there, I would have done things differently." While I understand where she's coming from, it's important for all horse owners to remember than exposure to infectious diseases is an ever-present risk. Streptococcus equi, and various other infectious agents, are widespread in the horse population, and there is never a "no-risk" situation. For that reason, we should be taking practical measures to reduce the risk of disease transmission at all times, not just when we know there is an infectious disease in the area.
One (of many) unique anatomical aspects of horses is their guttural pouches. These pouches open into the throat area and are essentially large openings in what is the equivalent of a horse's 
The fungal infection can weaken the wall of the artery, ultimately causing it to rupture. This results in massive blood loss (which comes out of the horse's nose) and it is a potentially life-threatening event.
I'm trying not to sound like a broken record when it comes to antibiotics, but it's a very important topic so you'll see many posts on the subject. When you consider that antibiotic-associated diarrhea is a potentially life-threatening problem in horses, and that antibiotic-resistant bacteria are becoming more common in general, it should be obvious that we need to limit the use antibiotics to when they are actually needed, and potentially effective. Horses with respiratory disease are commonly treated with antibiotics. However, as discussed in a previous post (
A few years ago, I investigated an equine herpesvirus (EHV) outbreak associated with a yearling sale. We found a lot of sick horses, both from the sale and horses that were infected when purchased horses were brought home. A lot of actively racing horses got sick and missed races, which cost people even more money. Part of the investigation was asking people what percentage of horses from sales they expected to get sick right after the sale. The average answer was 80%, and many people said 100%. When you think about it, it's absolutely astounding that people will spend what is often a great deal of money to buy a horse that they expect will get sick, and then (more often than not) put it in the same barn as their other horses, thereby putting all the animals at risk of infection..jpg)
Strangles is an infection caused by the bacterium Streptococcus equi subsp equi, which is often simply called Strep equi or S. equi for short. This pathogen is always circulating somewhere in the equine population, and it can cause sporadic cases of strangles in individual horses, or large outbreaks in groups. It is transmitted mainly by nasal secretions and pus from infected horses when they come in contact with other horses. The classical and most prominent feature of strangles is the formation of large abscesses in the lymph nodes between the jaw bones.
The downside of this kind of treatment is, while it stops the immediate infection from developing, the horse does not develop immunity against S. equi like it would if its body had to fight the infection. This is not a problem if good infection control measures are in place to prevent further S. equi transmission. However, if transmission is not controlled, then the horse is at risk of being re-exposed, and could be infected again after the antibiotics are stopped. This can lead to a vicious cycle of exposure-treatment-susceptiblity-exposure-treatment... I've seen farms where this goes on for a long time with horses receiving multiple courses of antibiotics, and they often eventually getting the disease anyway.
As of this morning, no new cases of equine herpesvirus (EHV) infection have been identified at Laurel Park in Maryland. (.jpg)
Respiratory tract disease is a very common problem in horses that has a wide range of causes, including bacterial and viral infections, as well as non-infectious conditions. Nasal discharge (i.e. a "snotty nose") is often one of the first signs of respiratory disease noticed by owners. Unfortunately, the nasal discharge itself cannot tell you what the problem is, nor how to deal with it. If your horse develops nasal discharge, you should contact your veterinarian to determine the best approach to diagnose the cause and the best way to treat the animal. Here are just a few of the factors that need to be considered:
As we encounter more infections caused by antibiotic-resistant bacteria (e.g. 
Equine herpesvirus type 1 (EHV-1) infection was confirmed in a filly at Laurel Park in Maryland (
As every horse breeder should know, colostrum is one of the keys to any foal's survival. This antibody-rich first milk is critical for preventing early, often fatal infections in foals. Foals that don't get an adequate volume of good quality colostrum within the first 18-24 hours of life (while they can still absorb antibodies through their intestine) are at high risk of dying from any of a number of different infections.
The discovery of antibiotics was one of the most important medical advances in history, and these drugs have had an immense impact on human and animal health. While antibiotics have saved countless lives, their use can also be associated with some very serious side effects and complications. For example, in horses, antibiotic-associated diarrhea (colitis) is a major issue.
Recently, I wrote about a 
The main equIDblog page is regularly updated with posts about equine infectious disease, in a blog format. It provides information and commentaries about recent and important issues pertaining to this field. New posts will be going up every day or so, so check back regularly. Periodically there will also be "case posts", which describe a horse with a particular infectious disease, with an emphasis on explaining what the problems and issues are with similarly affected horses..jpg)
The described clinical signs in affected horses are very non-specific, so it's hard to speculate about the causative pathogen. There are a variety of potential culprits, including equine influenza virus (EIV), but so far testing has not detected EIV or any other known pathogens. This "mystery" disease does not appear to affect other animals or people (but without knowing what is causing it, this is difficult to say for certain). It is possible that this is a "new" disease, but the vast majority of infectious disease outbreaks are caused by pathogens that we already know about. Specialists from Britain have been called in to help with the investigation. Hopefully more information will be available soon.
One area that people often ask questions about is the ability of S. equi to survive outside of a horse, and how to handle the general environment (e.g. barn, paddocks) during an outbreak of strangles. Two older studies reported that S. equi can survive on environmental surfaces for up to 60 days. This has led some people to recommend prolonged quarantine of pastures that have been used by infected horses. However, these studies were conducted in the controlled and relatively hospitable environment of a laboratory, without exposure to sunlight, temperature changes and competing bacteria that are found in the "real world".
Eastern equine encephalitis (EEE) was recently identified as the 
You may notice a recurring theme on equIDblog anytime we talk about infectious disease control, particularly when it comes to zoonotic diseases (those that can be transmitted between animals and people): an emphasis on handwashing. There is increasing emphasis on hand hygiene (i.e. hand washing and use of alcohol hand sanitizers) education in hospitals because the hands of healthcare workers are a major (if not the most important) means of disease transmission between patients. Despite hand hygiene being easy, cheap and effective, people rarely wash their hands as often as they should, and they often don't do it properly.
Many people in the horse world have heard the hype about methicillin-resistant Staphylococcus aureus (MRSA) in horses. MRSA can cause infection in horses, just like it can in people, dogs, cats and many other animals. It’s usually what we call an “opportunistic” pathogen, meaning it usually takes advantage of a person or an animal that is already sick or injured, like someone who’s in the hospital and has just had surgery. And because MRSA is resistant to many different antibiotics, the infection can be difficult to treat. The big concern with MRSA in recent years is that infections are now sometimes occurring in people who aren’t sick, and who don’t have wounds or incisions, which is where MRSA usually likes to move in. It’s very important to find out from the start if an infection is being caused by MRSA, so that it can be prevented from spreading to other people and animals, and so that it can (if necessary) be treated with the right kind of antibiotic..jpg)
Biosecurity is a term often used in association with rearing of food animals, particularly chickens and pigs. In these types of facilities, new animals are rarely or never introduced to an established group, control of personnel access is very strict, and significant efforts are made to prevent exposure of animals to new infectious agents.
In adult horses, botulism is caused by ingesting a toxin produced by the bacterium Clostridium botulinum. This bacterium will not grow in the presence of oxygen, however in can grow in conditions that are sometimes present in improperly fermented haylage and silage. As the bacterium grows, it produces botulinum toxin, one of the most potent toxins on the planet. Ingestion of botulinum toxin leads to progressive paralysis (i.e. severe weakness and flacid muslces).
Your veterinarian obtains vaccines through a reputable distribution system, which ensures quality control, tracking of products, and proper shipping and storage conditions. When you buy vaccines from other sources(especially the internet), you don't have that same level of assurance. Vaccines that have been improperly handled may not be effective.
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