Initial occurrence of Taylorella asinigenitalis and its detection in nurse mares, a stallion and donkeys in Kentucky.

The research article discusses an outbreak of the bacterium Taylorella asinigenitalis among equine populations in Kentucky in 1998, which was isolated from the external genitalia and reproductive tracts of nurse mares, a stallion, and donkey jacks. The study also looks at the transmission of the bacterium and treatment efforts to clear it from affected horses.

Identification and Isolation of Taylorella asinigenitalis

• The study started in 1998 when Taylorella asinigenitalis, a newly identified bacterium, was found in the external genitalia and reproductive tracts of nurse mares, a stallion, and donkey jacks in Kentucky.
• This bacterium was isolated from the reproductive tract of 10 adult equids, including two donkey jacks, one Paint Quarter-horse stallion, and seven draft-type breeding mares.

No Observable Clinical Signs

• Despite the presence of the bacterium, none of the infected horses showed clinical signs of reproductive tract disease, which suggests that it doesn’t necessarily cause noticeable symptoms or illness.

The Increased Risk of Taylorella asinigenitalis between Breeding Pairs

• The study found that the odds of being culture positive (having traceable amounts of the bacterium) were 20 times greater for a mare that was bred with a donkey compared to a mare bred with a stallion.
• About 18% of the mares that bred with either a carrier stallion or donkey jack tested positive for the culture.

Eradication Efforts and Long-term Effects

• A large-scale regulatory effort was initiated to contain the outbreak, which involved tracing and testing 232 horses and donkeys across 58 properties.
• 71% of the mares that tested positive required more than a single course of treatment in order to completely clear the bacterium from their reproductive tracts.
• One mare was found to still be harboring the organism for more than 300 days post infection.