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CEM Returns to US; Three Exposed Mares Quarantined in Pennsylvania

By Suzanne Bush

Contagious Equine Metritis (CEM) has reappeared in the United States after the disease had been virtually eradicated here for 30 years. A serious venereal disease, CEM was first diagnosed in England in 1977, according to the United States Department of Agriculture's Animal and Plant Health Inspection Service (APHIS). Although CEM is not fatal, it can become a chronic condition and can wreak havoc with breeding programs, causing infertility in mares, or spontaneous abortion. In that regard, it has the potential of creating severe economic hardships for the equine industry, given the cost of quarantine, the time it takes to clear the infection, the numerous tests required to ensure that the bacteria have been cleared from exposed animals and the disruption in breeding.

According to Craig Shultz, DVM, Director of Pennsylvania's Bureau of Animal Health and Diagnostic Services, there are three exposed mares currently quarantined in Pennsylvania. He says efforts to determine how CEM slipped through the quarantine procedures in place at the country's import centers and CEM quarantine facilities are ongoing.

Quarantine Facilities Critical

Federal law requires quarantine at an approved facility for all breeding horses more than two years old imported to the US. These facilities are separate and in addition to the quarantine facilities in New York, Miami and Los Angeles, where all imported horses are inspected and held for anywhere from three to 60 days upon their arrival in the US. Steven Finch, DVM, of the United States Department of Agriculture (USDA) says that about 4,600 horses pass through the import facilities each year.

Shultz says that, while CEM is treatable, it is often undetected, and a single breeding stallion can pass it to several mares before symptoms become apparent. "Diagnosis involves blood tests and multiple swabbing of areas most likely to be positive. They do multiple swabbing on exposed mares. It's not one simple test. Stallions also require extensive testing." According to APHIS, it could take several months for the bacteria to clear from an infected mare's uterus. CEM is often mistaken for other more common genital infections in mares, contributing further to its spread.

Because CEM can also be spread by artificial insemination and contact with contaminated lab instruments—even by hands—rigorous attention to hygiene and protocols for disinfecting instruments is an important key to prevention.

Mapping CEM's Spread

According to the APHIS update on CEM, 433 CEM-exposed horses have been identified. This includes 54 stallions and 389 mares in 45 states. In addition there are at least 65 mares thought to have been exposed to CEM, and these mares are still being traced. "CEM is considered a reportable disease," says Finch. "Veterinarians suspecting CEM from clinical signs or history should notify their State Veterinarian or USDA Area Veterinarian in Charge. When laboratories diagnose CEM they report the result to the State Veterinarian and USDA."

He says that they are still trying to find where and how the outbreak began. "None of the positive horses have yet been identified as the source of the outbreak; the epidemiologic investigation continues to pursue all available information relative to determining the origin of this outbreak, but no conclusions can yet be drawn."

Treatment Protocols

CEM has not been seen in the US in many years; but that doesn't mean there is not a current, effective plan for treating it. "APHIS has developed protocols for the different types of horses involved—stallions, mares, foals. These protocols have been developed with the assistance of state animal health officials, recognized world experts in the disease and APHIS epidemiologists. The protocols are distributed to state and federal animal health officials in the affected states who communicate the protocols to owners."

The regimen includes daily washing of external genitalia with disinfectants and antibiotics, followed by application of antibiotic ointment.

No Changes at Facilities

Finch says that there have been no changes yet at the nation's import facilities as a result of the CEM outbreak. USDA's previously-announced plans for licensing private CEM quarantine facilities have been stalled during the transition to the new administration, he says, but they will probably resume shortly.

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