On Aug. 26, a 3-year-old Standardbred gelding in Carroll County, Maryland, tested positive for West Nile virus (WNV). The gelding, who is unvaccinated, developed neurologic deficits on Aug. 20. He is still alive. 

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.

WNV 101

West Nile virus is transmitted to horses via bites from infected mosquitoes. Not all infected horses show clinical signs, but those that do can exhibit:

• Flulike signs, where the horse seems mildly anorexic and depressed;
• Fine and coarse muscle and skin fasciculation (involuntary twitching);
• Hyperesthesia (hypersensitivity to touch and sound);
• Changes in mentation (mental activity), when horses look like they’re daydreaming or “just not with it”;
• Occasional drowsiness;
• Propulsive walking (driving or pushing forward, often without control); and
• Spinal signs, including asymmetrical weakness; and
• Asymmetrical or symmetrical ataxia.

West Nile virus has no cure. However, some horses can recover with supportive care. Equine mortality rates can reach 30-40%.

Studies have shown that vaccines can be effective WNV prevention tools. Horses vaccinated in past years need an annual booster shot, but veterinarians might recommend two boosters annually—one in the spring and another in the fall—in areas with prolonged mosquito seasons. In contrast, previously unvaccinated horses require a two-shot vaccination series in a three- to six-week period. It takes several weeks for horses to develop protection against the disease following complete vaccination or booster administration.

In addition to vaccinations, owners should work to reduce mosquito population and breeding areas and limit horses’ mosquito exposure by:

• Removing stagnant water sources;
• Dumping, cleaning, and refilling water buckets and troughs regularly;
• Keeping animals inside during insect feeding times (typically early in the morning and evening); and
• Applying mosquito repellents approved for equine use.

According to the Maryland Department of Agriculture, 17 horses at a boarding facility in Baltimore County are suspected to be positive for strangles. In addition, 28 horses have been exposed. The suspected cases are under official 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.

Three horses in Maryland recently tested positive for strangles. In Calvert County, a 5-year-old warmblood gelding at a boarding facility tested positive on Aug. 21. In St. Mary’s County, two horses at a private facility are positive, including a suckling Hanoverian colt. The horses are under official 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.

Two horses in Maryland recently tested positive for strangles. The horses live in Montgomery and Anne Arundel counties. 

In Montgomery County, one mare at a boarding facility was confirmed positive for strangles on Aug. 7. The mare is under quarantine, and it is unknown if other horses are exposed. 

In Anne Arundel County, a 21-year-old Thoroughbred mare at a boarding facility tested positive on Aug. 7. The mare is under quarantine, and it is unknown if other 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.

On July 18, a suckling Quarter Horse colt in Washington County, Maryland, tested positive for salmonellosis. The foal developed clinical signs on July 14, including fever, diarrhea, and sepsis. He is isolated, and 11 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 Salmonellosis

Salmonellosis is a contagious and zoonotic bacterial infection caused by Salmonella spp, which causes enterocolitis. Clinically normal horses can transiently shed Salmonella, with shedding more common during: 

• Concurrent illness: antibacterial usage, physiological disturbance
• Stress: transportation, social, nutritional 
• Gastrointestinal disturbance: motility (especially colic), feed change

Clinical signs of salmonellosis include diarrhea, fever, lethargy, anorexia, colic, localized infection, sepsis and septic shock. Foals are commonly more seriously affected with profound systemic illness, including hemorrhagic diarrhea, pneumonia, meningitis, inflammation of growth plate and septic arthritis. 

Treatment of the severe form of salmonellosis is based on IV fluid and electrolyte replacement and efforts to control the host’s responses initiated by the systemic inflammatory response.

Prevention of salmonellosis is difficult, because the organism is present in the environment as well as in the feces of some healthy animals. Isolation and increased biosecurity are needed to prevent spread of the disease.

Two horses in Maryland—one in Carroll County and one in Cecil County—recently tested positive for strangles. In addition to the two confirmed cases, 20 horses in Carroll County and 50 horses in Cecil County 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 April 16, one horse at a boarding facility in Montgomery County, Maryland, tested positive for strangles. Seventy-three exposed horses were also tested, and three of those horses have since tested positive. The four positive horses are quarantined and will be tested again after 21 days. Staff is monitoring exposed horses daily for new symptoms, and the farm is complying with state quarantine procedures. 

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.

One horse at a boarding facility in Montgomery County, Maryland, recently tested positive for strangles. Seventy-three horses are exposed and will be tested this week. The affected horses are 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 March 18, an 8-year-old Arabian gelding in Carroll County, Maryland, was diagnosed with putative intestinal hyperammonemia secondary to salmonellosis. The gelding initially developed colic and fever on March 15 and was referred to a hospital for treatment and diagnostics. He remains hospitalized but is responding to medical management. 

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 Salmonellosis

Salmonellosis is a contagious and zoonotic bacterial infection caused by Salmonella spp, which causes enterocolitis. Clinically normal horses can transiently shed Salmonella, with shedding more common during: 

• Concurrent illness: antibacterial usage, physiological disturbance
• Stress: transportation, social, nutritional 
• Gastrointestinal disturbance: motility (especially colic), feed change

Clinical signs of salmonellosis include diarrhea, fever, lethargy, anorexia, colic, localized infection, sepsis and septic shock. Foals are commonly more seriously affected with profound systemic illness, including hemorrhagic diarrhea, pneumonia, meningitis, inflammation of growth plate and septic arthritis. 

Treatment of the severe form of salmonellosis is based on IV fluid and electrolyte replacement and efforts to control the host’s responses initiated by the systemic inflammatory response.

Prevention of salmonellosis is difficult, because the organism is present in the environment as well as in the feces of some healthy animals. Isolation and increased biosecurity are needed to prevent spread of the disease.

On March 13, a 3-year-old Thoroughbred stallion in Barn 31 at the Laurel Park Racetrack in Prince George’s County, Maryland, tested positive for equine herpesvirus-1 (EHV-1). The horse developed clinical signs on March 7, including fever and hind limb cellulitis. He is currently still alive. 

An Animal and Facility Hold Order has been placed on Barn 31.

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.

EHV 101

Herpesvirus is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and EHM.

In many horses, the first or only sign of EHV-1 infection is fever, which can go undetected. In addition to fever, other common signs of EHV-1 infection in young horses include cough, decreased appetite, depression, and a nasal discharge. Pregnant mares typically show no signs of infection before they abort, and abortions usually occur late in gestation (around eight months) but can be earlier. Abortions can occur anywhere from two weeks to several months following infection with EHV-1.

Horses with EHM usually have a fever at the onset of the disease and might show signs of a respiratory infection. A few days later, neurologic signs such as ataxia (incoordination), weakness or paralysis of the fore- and hind limbs, urine retention and dribbling, loss of tail tone, and recumbency (inability to rise) develop.

Herpesvirus is easily spread by nose-to-nose or close contact with an infectious horse; sharing contaminated equipment including bits, buckets, and towels; or clothing, hands, or equipment of people who have recently had contact with an infectious horse. Routine biosecurity measures, including hygiene and basic cleaning and disinfection practices, should be in place at all times to help prevent disease spread.

Current EHV-1 vaccines might reduce viral shedding but are not protective against the neurologic form of the disease. Implementing routine biosecurity practices is the best way to minimize viral spread, and the best method of disease control is disease prevention.