As you can imagine, swelling in the jaw or throat region can influence how a horse accepts the bridle. When a swollen area is under compression or load, such as when we ask the horse to come onto the bit, we can experience all kinds of resistance, ranging from slightly stronger or weaker pressure on the bit to severe, adverse behaviors such as rearing, headshaking and pulling on the reins.

In all cases of a sudden change in contact, it is a good idea to carefully inspect the jaw and throat region. Ask your veterinarian for assistance and advice when you notice abnormalities or you run into clear contact or connection problems. The anatomy of the head, neck and jaw is complex, and with many different structures found in this region, it is important to determine, if possible, which specific structures are associated with the swelling. Lumps and bumps may result from direct trauma, indicate inflammation or may develop from the accumulation of tissue in a more chronic process. 

Evaluation of any bump begins with physically examining the area to determine the exact location and to check for wounds, skin irritation, heat or sensitivity. Palpation of the lump to determine its characteristics may help identify which tissues are involved. For example, bone will be hard. Additional diagnostic procedures, including radiographs (X-rays), ultrasound, endoscopy or even biopsy, may be necessary to get a complete clinical picture. 

While we can’t go over every cause for lumps under the jaw here, we can review the most common sources. These include swollen lymph nodes, reactive salivary glands and dental matters. 

Lymph Nodes

Horses have two major sets of lymph nodes located near the jaw: the submandibular lymph nodes, found between the mandibles (lower jawbones), and the retropharyngeal lymph nodes, situated near the throat. Lymph nodes are a part of the immune system and they become enlarged when they react to an ongoing process.

Localized infections, such as an abscessed tooth, are likely to result in enlargement of a single lymph node close to the site of infection. In contrast, respiratory illness may result in swelling of one or more nodes. Many viral infections will cause mild lymph-node enlargement that resolves in one to two weeks with no special treatment.

Streptococcus equi, also known as “strangles,” is a bacterial infection that can result in severe enlargement of the retropharyngeal lymph nodes. This type of swelling may be seen and felt just behind the mandible. 

Horses with strangles will run a fever and may develop thick nasal discharge. In some cases, the affected lymph nodes may become so enlarged that they put pressure on the horse’s airway.

Reactive Salivary Glands

Swelling of the salivary glands is commonly seen in horses turned out to pasture in the spring. The parotid glands are the largest salivary glands and are found on both sides of the head, extending from the jaw to the base of the ear. 

These glands produce saliva, and affected horses may drool excessively. A toxin produced by a fungus on clover is believed to be at the root of this reaction. This condition is usually not painful, but swelling may be significant enough to prevent the horse from flexing well at the poll. 

Simply avoiding pasture turnout for a few weeks usually remedies the problem. Rarely, the salivary glands become infected or develop blockages that can also result in swellings. You should seek advice if swellings in this area come up at other times of year or don’t resolve quickly.

Dental Matters

Teething bumps, or eruption cysts, are hard enlargements seen along the jawline in horses younger than 5 years of age. The bumps are caused by changes in the bone as the permanent premolar and molar teeth emerge and displace the deciduous, or “baby,” teeth. 

Several such swellings can usually be felt at the same time and are equal in size. They should not be painful or hot. Occasionally bumps may also be noted along the bridge of the nose as a similar process can occur with the upper teeth. In general, teething bumps are strictly cosmetic and should spontaneously resolve as the horse matures. 

Occasionally, teething bumps are an indication of problems in shedding of the deciduous teeth, commonly known as “retained caps.” An oral exam by a veterinarian or veterinary dentist can be helpful to determine if more significant dental problems exist.

Other causes of lumps near the jaw include local trauma resulting in soft- tissue injury and even fractures, insect bites and, very rarely, tumors. 

You should consult with your veterinarian about any new swelling that persists for more than a few days or any lumps that are enlarging, painful or located in areas that interfere with your tack or riding.

About Kimberly Johnston, VMD, Dipl. ACVS 

Kimberly Johnston, VMD, Dipl. ACVS, graduated from the University of Pennsylvania and New Bolton Center. She became a diplomate of the American College of Veterinary Surgeons in 2010, specializing in sports medicine and orthopedic surgery. In her free time, she enjoys riding her 14-year-old Thoroughbred, Jazz, schooling Third Level. She and her FEI-dressage-riding husband, Rob van Wessum, DVM, operate Equine All-Sports Medicine Center in Mason, Michigan. 

Elizabeth Davis, DVM, professor and section head of equine medicine and surgery at Kansas State University’s College of Veterinary Medicine, says that more isn’t necessarily better when it comes to vaccinations. “It’s important to balance the risk of disease against the risk of overstimulating the immune system and triggering side effects,” she noted. “Vaccines greatly reduce disease, but they can’t always eliminate it entirely. However, you can use them along with smart management practices to limit your horse’s risk of infection.”

Here, we’ll help break down the equine vaccination guidelines provided by the American Association of Equine Practitioners to simplify your spring health-care routine for your horse’s particular needs, depending on where he lives and his risk of exposure to certain diseases. Above all, when it comes to vaccinating your individual horse, your veterinarian will always be your best and most important resource.

Vaccinate Based on Your Horse’s Needs

As with people, the equine immune system needs time to respond to a vaccine and build up white blood cell and antibody defenses. Ideally you should administer a vaccine approximately two to three weeks before your horse will be exposed to a potential risk. Keep in mind, however, that if your horse has never had a vaccination against a particular disease, your veterinarian may need to give an initial vaccine followed by a booster three to four weeks later to get full protection (this varies among vaccines). In this case, you’ll need to schedule the initial vaccine even sooner before potential exposure.

The same process that builds immunity can also produce side effects. Vaccines are tested for safety, but mild reactions, such as fever and local muscle soreness, are common. Less often, an intramuscular injection leads to a bacterial infection. In rare cases, vaccines have caused severe allergic reactions—so avoiding unnecessary vaccination is also important.

To tailor your horse’s vaccination program to his situation, consider the following:

• Age: Horses under 5 are more susceptible to certain diseases, such as equine herpesvirus and West Nile virus.
• Location: Your horse should be vaccinated against diseases he’s likely to encounter based on where he lives or is going to be shipped. Some risks are widespread, while some are regional and others are local.
• Lifestyle: Horses who travel to shows or venues where they encounter horses from other barns need protection against diseases that are spread from horse to horse. Those horses could bring infection onto the farm, so even horses that stay home need protection. Horses can carry some diseases without showing symptoms, shedding bacteria and viruses that could infect others.
• Use: Broodmares may need protection against diseases that can result in pregnancy loss. Revaccinating mares four to six weeks before foaling helps ensure high levels of antibodies in colostrum (first milk), which help protect foals in the first months of life.

You might think that older horses would build up immunity over the years and wouldn’t need many vaccinations, but there’s little evidence of that. “A 29-year-old horse at pasture may have less exposure to certain diseases, so he may need those vaccinations less often,” Davis explained.

But like people, whose immune response weakens with age, horses also show changes in their immune response during their senior years. “We don’t have evidence that older horses get sick more often than younger horses, but we do know it’s important to maintain proper vaccinations for this population,” she noted. “And many older horses develop equine Cushing’s disease, which suppresses the immune system. It’s important to treat them for that condition as well as keep their vaccinations up to date.”

The best course is to review your horse’s vaccination program with your vet annually to ensure it fits his current needs.

Timing is Key

If you’re planning have your veterinarian stick your horse for all his vaccines at once during his annual exam and Coggins test to avoid multiple barn-call fees, you might reconsider. In order to be protected from disease, your horse needs the right vaccinations at the right time to maximize protection.

Ideally, you should time your horse’s vaccinations to provide optimal protection against the disease, and the best time isn’t the same for all. For example, your doctor probably recommends you a get flu shot in the fall, so you’ll be protected when flu season kicks into high gear over the winter.

Vaccines for some diseases, such as tetanus and rabies, can be given any time of year. But for others, appropriate timing can be based on a number of factors including how the particular disease is spread, what region of the country you live in and whether your horse stays home in a closed herd or goes to shows (or has contact with show horses) and is thus more likely to be exposed.

For example, the risk of respiratory diseases that spread horse-to-horse, such as strangles, may jump when a horse moves from a private barn to a boarding stable with an indoor arena. Time vaccinations against those diseases to protect your horse then and during other times when he might be at risk.

The risk of insect-transmitted diseases such as Eastern and Western equine encephalitis, West Nile virus and Potomac horse fever are highest whenever the bugs emerge in your area. Consult your veterinarian for confirmation, but generally it’s advised to vaccinate against these diseases just before insect numbers surge in spring in northern parts of the country, while they may need to be administered more frequently in the south in other areas where it’s remaining warmer longer.

Vaccines Recommended for Most Horses in the U.S.

The AAEP designates certain vaccinations as “core,” recommended for practically all horses in the United States. They include:

Eastern equine encephalitis/Western equine encephalitis: Biting mosquitoes spread viruses that cause EEE and WEE. The viruses attack the horse’s nervous system, and EEE is the deadlier of the two—only about 10 percent of clinically affected horses survive. It occurs mainly in the eastern, Gulf Coast and midwestern states; WEE, which is less common, occurs mainly in the west. (Venezuelan equine encephalitis, a related virus, hasn’t been reported in the United States for more than 35 years. You don’t need to vaccinate against it unless your horse will travel to an area where the disease has been reported.)

• Vaccines for EEE and WEE are usually combined in a single shot, often with tetanus and other vaccines.
• Boosters should be given in spring so the horse can build immunity before mosquito populations peak in summer. “Hot, wet summers increase the risk for mosquito-borne diseases,” Dr. Davis notes.
• In areas where mosquitoes are active year-round and the risk is high, horses may need a second booster in the fall.

Rabies: A virus that attacks the nervous system causes rabies. It occurs in every state except Hawaii, mainly among wild animals (especially skunks, raccoons, foxes, coyotes and bats). Although it’s not common in horses, there are equine cases every year. A rabid animal wanders out of the woods and bites a horse, or the horse has a wound that becomes contaminated with saliva or blood from a rabid animal.

• Rabies is always fatal and poses risks to anyone in contact with an infected horse, but vaccination provides reliable protection.
• An annual booster can be given at any time of year. “In most states rabies vaccinations must be performed by a licensed veterinarian,” Dr. Davis says. “If you administer other vaccines yourself, consider having rabies administered when you schedule another veterinary procedure for your horse rather than as a separate farm call.”

Tetanus: Tetanus bacteria are everywhere, including the soil, where they form spores and become dormant. If they find their way into a penetrating wound, they germinate and begin to produce a potent neurotoxin. Horses are highly susceptible to the toxin, which causes violent muscle spasms and potentially fatal complications.

• Vaccination with tetanus toxoid (a weakened form of the toxin) gives safe and reliable protection.
• Vaccinated horses need an annual booster, which can be given at any time of year. If the horse gets a wound and it has been more than six months since his last booster, he should have another.

West Nile virus: Although WNV belongs to a different viral family than EEE, it also spreads via mosquitoes and attacks the horse’s nervous system. It first appeared in North America 15 years ago and has since spread throughout the continental United States and into Canada and Mexico. About a third of horses who develop clinical signs of WNV infection die, and survivors may have long-term gait and behavior problems.

• There are currently four licensed WNV vaccines based on different technologies, but all are safe and effective. Your vet can advise you on which is best for your horse.
• As with EEE/WEE, boosters should be given in spring to build immunity before mosquito season and repeated where the risk is year-round. This is especially important for young horses and older horses with Cushing’s disease, who are more susceptible to WNV.
• “If you import a horse, be aware that vaccination for these mosquito-borne diseases isn’t routine in Europe and the horse may have no protection against them. Find out the horse’s vaccination history, and get the initial series before he comes, so he’s protected on arrival,” Davis said.

Respiratory Risks

The AAEP lists other vaccinations as “risk-based”—the need depends on your horse’s situation and specific disease risks. Among the top risks are three respiratory diseases that spread horse to horse.

Flu: Equine influenza, which is caused by a virus, is among the most common infectious respiratory diseases in horses. The AAEP recommends this vaccination for all horses except those who live in a closed, isolated herd—they never leave the farm and have no contact with outside horses. For the rest, risk levels determine how often to administer a booster.

• Horses who show often or live in barns where horses are in and out should get a booster every six months.
• Horses who are only occasionally in contact with others can get along with an annual booster. Time it to maximize immunity when risk of exposure is highest.

There are three types of flu vaccines—inactivated, modified live virus (intranasal) and canarypox vector—all safe and effective. In unvaccinated horses the intranasal provides the quickest response.

Equine herpesvirus: Equine herpesvirus type 1 (EHV-1) and equine herpesvirus type 4 usually cause a flu-like illness (rhinopneumonitis) with fever and respiratory symptoms. EHV-1 can cause pregnant mares to abort, and in some cases the virus damages blood vessels in the brain and spinal cord, producing equine herpesvirus myeloencephalopathy (EHM), a neurologic disease that can be fatal. In recent years veterinarians have identified a strain of the EHV-1 virus that has caused serious outbreaks of EHM.

• Many horses are infected with EHV early in life as weanlings and carry the virus for life. Like other herpes viruses EHV goes latent, hiding in the body. When the horse is stressed—by shipping, fatigue or some other cause—the virus may become active. Carrier horses may not show signs of illness, but they can shed the virus and spread it to others. Vaccination helps prevent respiratory illness and reduce viral shedding.
• Some vaccines also help prevent loss of the foal from EHV-related causes and are labeled for that.
• There are no vaccines labeled effective against EHM. Some studies suggest that a modified live virus vaccine (Rhinomune MLV from Boehringer Ingelheim Vetmedica) or a high antigen-load killed vaccine labeled for preventing abortion (Pneumabort K from Zoetis) may lessen the severity of the neurologic disease, but more research is needed.

“For a horse at high risk, I would boost with one of these,” Davis said. “There is no evidence that vaccines labeled only for preventing respiratory EHV will protect against EHM.”

• Annual boosters are appropriate for most horses, but those at high risk—performance and show horses, horses under 5 years old and those on breeding farms or in contact with pregnant mares—may need boosters every six months.

Strangles: Strangles, caused by Streptococcus equi bacteria, is common and highly contagious. Early signs include fever, depression and cough, followed by swelling of the lymph nodes around the horse’s jaw and throatlatch. Soon a discharge of pus begins draining from the horse’s nose. Abscesses may form in the lymph nodes and burst open to drain. Occasionally the bacteria spread to lymph nodes elsewhere in the body and there can be serious complications. Young horses are often hardest hit.

Both killed injectable and modified live intranasal vaccines are available, and they can help prevent or reduce the severity of the disease. The AAEP recommends vaccination on farms where there is a history of outbreaks and for horses that are at high risk of exposure.

• “Strangles vaccines produce a strong response, and there is more risk of side effects than some other vaccines,” Dr. Davis says. “A horse that’s at low risk can probably skip this vaccination. This would be a horse that mainly stays on a farm, in a closed herd where the health status is known for all the horses and new arrivals are quarantined for two weeks. Even if the horse leaves the farm a few times a year, strangles vaccination may not be necessary because the risk of exposure is low.”
• For horses at high risk, such as those going to shows where many horses mingle and you’re not sure of biosecurity, vaccination may make sense. To lower the risk of side effects, Dr. Davis advises having your vet run a blood test to check your horse’s level of antibodies. Vaccinate only if the titer is below 1:1600.

Less-Common Risks

Talk with your veterinarian to assess your horse’s need for these vaccinations:

Potomac horse fever: If there have been cases of Potomac horse fever (equine monocytic ehrlichiosis) on your farm or nearby, your vet may recommend vaccination. This disease occurs in many areas of the country, but risk is local. It’s caused by a bacterial organism with a complicated life cycle, moving through parasitic flukes, water snails and insects. Horses are thought to pick up the bacteria by eating insects that die and fall into hay or pasture. These insects emerge in warm weather, so vaccinate in spring.

Equine viral arteritis: This respiratory disease is contagious but so mild that most horses don’t need vaccination. But the virus that causes it also causes abortion in pregnant mares. Broodmares can be vaccinated before breeding. So can stallions, who can carry and spread the virus without showing signs. Some countries bar stallions or mares if tests show antibodies to the virus. It’s impossible to tell whether vaccination or the disease triggered the antibodies, so the AAEP recommends documenting disease-free status by testing for antibodies before vaccinating against EVA for the first time.

Rotaviral diarrhea: Rotavirus is a major cause of foal diarrhea. Vaccinating pregnant mares helps protect their foals. Other horses don’t need this shot, and no evidence shows that vaccinating newborn foals has benefits.

Botulism: Broodmares can be vaccinated against the form of botulism that causes shaker foal syndrome. The vaccine protects their foals from this usually fatal condition, but it doesn’t protect horses from other forms of botulism.

Anthrax: Few horses need vaccination against anthrax; the bacteria that cause this deadly disease are found in scattered sites mainly in the Southwest.

Snakebite: A new vaccine promises to protect horses from the toxin delivered by western diamondback rattlesnakes, something to consider if you’re in snake country.

Takeaway

When it comes to assessing your horse’s springtime shots, strive to plan ahead so you and your veterinarian can work as a team to determine which vaccinations your horse needs and when you should administer them.

For More:

• For AAEP’s downloadable adult equine vaccination chart, click here.
• You can find AAEP’s downloadable foal vaccination chart here.

Strangles is a highly contagious bacterial infection of the upper respiratory tract in horses. It is characterized by swelling of the lymph nodes under the jaw or in the throat area and the formation of abscesses that may become large enough to obstruct the airway and affect a horse’s breathing (thus the term “strangles”).

A strangles-like disease was described long ago in Roman circus horses and later, in the mid-1200s, in Germany. It occurs worldwide, and in 2017 became a reportable disease in the United States because of its contagiousness and frequency. Horses of all ages—as well as donkeys and mules—may develop strangles. Youngsters from 1 to 5 years old generally experience the most severe infections. Foals younger than 4 months gain some protection through antibodies they receive in their dam’s colostrum. 

Most horses recover from strangles with only supportive care and develop strong protective immunity that lasts for about a year, often much longer. The condition can take three to six weeks to resolve. Some horses who appear healthy may continue to harbor and intermittently shed the bacteria.

Strangles is rarely fatal in otherwise healthy horses. However, life-threatening complications can occur. Metastatic strangles (“bastard strangles”) is associated with abscesses in lymph nodes in the abdomen and chest. A rare complication is purpura hemorrhagica, with immune-mediated damage—caused by the immune system mistakenly targeting the body—to blood vessels throughout the body.

Cause

Strangles is caused by Streptococcus equi, a bacterium that spreads from horse to horse through direct contact. It is also transmitted via contaminated equipment: water buckets, tack, blankets, grooming tools, stall-cleaning implements, trailers—virtually any item in an infected horse’s vicinity. This includes bedding and feed. Caretakers, too, may pass the bacteria, which can cling to hands and clothing. Streptococcus equi can stay active in moist conditions for four to six weeks and survives only briefly in drier areas, for instance on fences or in soil, for one to three days.

Signs

The incubation period for strangles is approximately three to 14 days after exposure. The first noticeable sign is sudden fever as high as 106 degrees Fahrenheit. Clear discharge likely will begin draining from the horse’s nose. It will turn thick and white to yellow in color. A few days after the onset, the lymph nodes under the jaw will swell and become painful. Eventually, these abscesses will rupture, draining through the skin or into the guttural pouches (large air-filled sacs in the throatlatch region). A horse with strangles may hold his head and neck in an abnormal position because of the abscesses. Other signs may include:

• difficulty swallowing
• labored breathing
• coughing
• loss of appetite
• lethargy
• depression.

Diagnosis

If you suspect that your horse has strangles, call your veterinarian as soon as possible. A bacterial culture of secretions from an abscess or a nasal swab or wash will confirm whether a horse has strangles. Culture is less sensitive than commonly used PCR tests, which detect DNA of S. equi. However, a positive PCR test is not proof of the presence of infectious bacteria.

Management

Start by isolating the sick horse. Identify any others who may be infected by checking their rectal temperature, and then isolate them, too, if they have a fever. A separate barn is ideal. If that’s not available, use a stall that is 15 to 20 feet away rom other horses. Designate specific items for a sick horse’s use; don’t share them with others. Use household bleach or a cleaning product containing phenol to disinfect equipment that might have been contaminated. Handle a sick horse last if you are caring for others. Wear disposable gloves when tending to him and wash your hands afterward. Change clothes, including shoes, before coming in contact with other horses. Continue to be cautious until a test sample returns clean.

Treatment

Your veterinarian will recommend a treatment strategy based on the severity of your horse’s infection. For an uncomplicated case of strangles, she’s likely to prescribe supportive care: 

• Shelter the horse in a comfortable, dry, well-ventilated environment that’s neither too hot nor too cold.
• Provide palatable, soft feed that’s easy to swallow. 
• Apply warm compresses to swollen areas to encourage the abscesses to drain.
• Flush ruptured abscesses with dilute povidone iodine solution (3 to 5 percent) for several days until drainage ceases.

In some cases, a veterinarian may prescribe a nonsteroidal anti-inflammatory medication to decrease pain and fever and increase appetite. But unless your horse’s infection is severe, she’ll likely refrain from recommending antibiotics because they can prolong recovery and interfere with the infected individual’s ability to develop a strong immune response to prevent reinfection.

Prevention

Medical: Two types of strangles vaccine are licensed for use in the U.S.: an intramuscular injectable and an intranasal form. Neither eliminates the risk of developing the disease, but either one can lessen the severity of an infection. Your vet can discuss the pros and cons with regard to your horse’s circumstances and potential risk of exposure. An initial dose of either type is administered to a healthy horse and followed by a booster three to four weeks later.

Management: Good caretaking practices at a stable or farm can significantly reduce the chances of a horse developing strangles and then infecting others on the premises. It’s advisable to:

• have sufficient space indoors and outside to avoid overcrowding
• take steps to ensure that housing is clean and dry 
• be conscientious about the cleanliness of equipment, especially if it’s shared, such as feeders and water troughs
• manage manure responsibly
• control rodents to avoid disease spread 
• quarantine any horse new to the property for three weeks.

There are additional precautions you can take if your horse routinely travels to shows and events:

• Avoid mingling with other horses, particularly those you don’t know.
• Minimize the use of shared stalls and pastures.
• Bring feed, buckets and equipment from home and designate them specifically for your horse’s use.
• Consider that travel may stress your horse and decrease his body’s ability to fight illness.
• Stay up to date on the location and extent of recent reported outbreaks.  

Practical Horseman thanks John F. Timoney, MVB, PhD, for his technical assistance in the preparation of this article. Dr. Timoney is professor emeritus at the University of Kentucky Gluck Equine Research Center. His specialties include equine bacterial diseases, immunology and equine education and research.

This article originally appeared in the Winter 2024 issue of Practical Horseman. 

On October 18, a 2-year-old Friesian gelding in Allegan County, Michigan, tested positive for strangles. The owner acquired the horse in mid-September, and he was already sick with a fever, nasal discharge, and abscessed lymph nodes at that time. He is now recovering, and five additional horses are potentially exposed.

EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.

About Strangles

Strangles in horses is an infection caused by Streptococcus equi subspecies equi and spread through direct contact with other equids or contaminated surfaces. Horses that aren’t showing clinical signs can harbor and spread the bacteria, and recovered horses remain contagious for at least six weeks, with the potential to cause outbreaks long-term.

Infected horses can exhibit a variety of clinical signs:

• Fever
• Swollen and/or abscessed lymph nodes
• Nasal discharge
• Coughing or wheezing
• Muscle swelling
• Difficulty swallowing

Veterinarians diagnose horses using polymerase chain reaction (PCR) testing with either a nasal swab, wash, or an abscess sample, and they treat most cases based on clinical signs, implementing antibiotics for severe cases. Overuse of antibiotics can prevent an infected horse from developing immunity. Most horses make a full recovery in three to four weeks.

A vaccine is available but not always effective. Biosecurity measures of quarantining new horses at a facility and maintaining high standards of hygiene and disinfecting surfaces can help lower the risk of outbreak or contain one when it occurs.

On October 5, a yearling Quarter Horse colt in Osceola County, Michigan, tested positive for strangles after developing an abscess below the jaw. The horse is currently recovering, and four additional horses are exposed. 

EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.

About Strangles

Strangles in horses is an infection caused by Streptococcus equi subspecies equi and spread through direct contact with other equids or contaminated surfaces. Horses that aren’t showing clinical signs can harbor and spread the bacteria, and recovered horses remain contagious for at least six weeks, with the potential to cause outbreaks long-term.

Infected horses can exhibit a variety of clinical signs:

• Fever
• Swollen and/or abscessed lymph nodes
• Nasal discharge
• Coughing or wheezing
• Muscle swelling
• Difficulty swallowing

Veterinarians diagnose horses using polymerase chain reaction (PCR) testing with either a nasal swab, wash, or an abscess sample, and they treat most cases based on clinical signs, implementing antibiotics for severe cases. Overuse of antibiotics can prevent an infected horse from developing immunity. Most horses make a full recovery in three to four weeks.

A vaccine is available but not always effective. Biosecurity measures of quarantining new horses at a facility and maintaining high standards of hygiene and disinfecting surfaces can help lower the risk of outbreak or contain one when it occurs.

A 3-year-old Shetland Pony mare in Muskegon County, Michigan, recently tested positive for strangles after developing clinical signs on September 17, including nasal discharge, fever, and a swollen lymph node. She is under quarantine. 

EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.

About Strangles

Strangles in horses is an infection caused by Streptococcus equi subspecies equi and spread through direct contact with other equids or contaminated surfaces. Horses that aren’t showing clinical signs can harbor and spread the bacteria, and recovered horses remain contagious for at least six weeks, with the potential to cause outbreaks long-term.

Infected horses can exhibit a variety of clinical signs:

• Fever
• Swollen and/or abscessed lymph nodes
• Nasal discharge
• Coughing or wheezing
• Muscle swelling
• Difficulty swallowing

Veterinarians diagnose horses using polymerase chain reaction (PCR) testing with either a nasal swab, wash, or an abscess sample, and they treat most cases based on clinical signs, implementing antibiotics for severe cases. Overuse of antibiotics can prevent an infected horse from developing immunity. Most horses make a full recovery in three to four weeks.

A vaccine is available but not always effective. Biosecurity measures of quarantining new horses at a facility and maintaining high standards of hygiene and disinfecting surfaces can help lower the risk of outbreak or contain one when it occurs.

On September 24, an 8-year-old Quarter Horse mare in Tuscola County, Michigan, tested positive for strangles. The mare developed clinical signs on July 26, including nasal discharge, a cough, and a mandibular abscess. She is currently recovering, and three additional cases are suspected.

EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.

About Strangles

Strangles in horses is an infection caused by Streptococcus equi subspecies equi and spread through direct contact with other equids or contaminated surfaces. Horses that aren’t showing clinical signs can harbor and spread the bacteria, and recovered horses remain contagious for at least six weeks, with the potential to cause outbreaks long-term.

Infected horses can exhibit a variety of clinical signs:

• Fever
• Swollen and/or abscessed lymph nodes
• Nasal discharge
• Coughing or wheezing
• Muscle swelling
• Difficulty swallowing

Veterinarians diagnose horses using polymerase chain reaction (PCR) testing with either a nasal swab, wash, or an abscess sample, and they treat most cases based on clinical signs, implementing antibiotics for severe cases. Overuse of antibiotics can prevent an infected horse from developing immunity. Most horses make a full recovery in three to four weeks.

A vaccine is available but not always effective. Biosecurity measures of quarantining new horses at a facility and maintaining high standards of hygiene and disinfecting surfaces can help lower the risk of outbreak or contain one when it occurs.

On September 13, three horses at a private facility in Lee County, Florida, tested positive for strangles. The horses are under official quarantine, and 23 horses are exposed. 

EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.

About Strangles

Strangles in horses is an infection caused by Streptococcus equi subspecies equi and spread through direct contact with other equids or contaminated surfaces. Horses that aren’t showing clinical signs can harbor and spread the bacteria, and recovered horses remain contagious for at least six weeks, with the potential to cause outbreaks long-term.

Infected horses can exhibit a variety of clinical signs:

• Fever
• Swollen and/or abscessed lymph nodes
• Nasal discharge
• Coughing or wheezing
• Muscle swelling
• Difficulty swallowing

Veterinarians diagnose horses using polymerase chain reaction (PCR) testing with either a nasal swab, wash, or an abscess sample, and they treat most cases based on clinical signs, implementing antibiotics for severe cases. Overuse of antibiotics can prevent an infected horse from developing immunity. Most horses make a full recovery in three to four weeks.

A vaccine is available but not always effective. Biosecurity measures of quarantining new horses at a facility and maintaining high standards of hygiene and disinfecting surfaces can help lower the risk of outbreak or contain one when it occurs.

Two horses in Ontario recently tested positive for strangles. The horses live in Oxford and Simcoe counties. 

In Oxford County, a 20-year-old Belgian mare developed clinical signs on September 9, including an abscess on the side of her head that was positive for S. equi on PCR testing. The horse is recovering. 

In Simcoe County, a 13-year-old gelding was admitted to a referral hospital with a fever and mucopurulent nasal discharge. Upper respiratory tract samples were positive for S. equi. The horse is recovering. 

EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.

About Strangles

Strangles in horses is an infection caused by Streptococcus equi subspecies equi and spread through direct contact with other equids or contaminated surfaces. Horses that aren’t showing clinical signs can harbor and spread the bacteria, and recovered horses remain contagious for at least six weeks, with the potential to cause outbreaks long-term.

Infected horses can exhibit a variety of clinical signs:

• Fever
• Swollen and/or abscessed lymph nodes
• Nasal discharge
• Coughing or wheezing
• Muscle swelling
• Difficulty swallowing

Veterinarians diagnose horses using polymerase chain reaction (PCR) testing with either a nasal swab, wash, or an abscess sample, and they treat most cases based on clinical signs, implementing antibiotics for severe cases. Overuse of antibiotics can prevent an infected horse from developing immunity. Most horses make a full recovery in three to four weeks.

A vaccine is available but not always effective. Biosecurity measures of quarantining new horses at a facility and maintaining high standards of hygiene and disinfecting surfaces can help lower the risk of outbreak or contain one when it occurs.

On September 11, a 9-year-old pony gelding in Union County, Ohio, tested positive for strangles. The pony developed clinical signs on September 9, including coughing and mild nasal discharge. He is under quarantine. 

Two exposed horses are also suspected positive for strangles, including a Miniature Horse gelding with nasal discharge, a cough, and a fever, and a Welsh cross gelding with a cough. 

EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.

About Strangles

Strangles in horses is an infection caused by Streptococcus equi subspecies equi and spread through direct contact with other equids or contaminated surfaces. Horses that aren’t showing clinical signs can harbor and spread the bacteria, and recovered horses remain contagious for at least six weeks, with the potential to cause outbreaks long-term.

Infected horses can exhibit a variety of clinical signs:

• Fever
• Swollen and/or abscessed lymph nodes
• Nasal discharge
• Coughing or wheezing
• Muscle swelling
• Difficulty swallowing

Veterinarians diagnose horses using polymerase chain reaction (PCR) testing with either a nasal swab, wash, or an abscess sample, and they treat most cases based on clinical signs, implementing antibiotics for severe cases. Overuse of antibiotics can prevent an infected horse from developing immunity. Most horses make a full recovery in three to four weeks.

A vaccine is available but not always effective. Biosecurity measures of quarantining new horses at a facility and maintaining high standards of hygiene and disinfecting surfaces can help lower the risk of outbreak or contain one when it occurs.