The Horse

MAR 2019

The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.

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Page 48 of 75

A28 March 2019 The Horse | AAEP Wrap-Up ALEXANDRA BECKSTETT Managing Postpartum Metritis U terine wall inflammation, known as metritis, is one of the most common yet serious postpartum diseases veterinarians treat in mares. And because it takes four-plus days to get culture results indicating which antibiotic is most effective against bacteria present, most treat before culture results are back. Maria Ferrer, DVM, Dipl. ACT, as- sociate professor of theriogenology in the University of Georgia's Department of Large Animal Medicine, in Athens, sought to develop more specific treatment recommendations for affected mares. She evaluated records of 45 mares diagnosed with metritis within six days of foaling that received a variety of antimicrobial types. Twenty-eight (62.2%) mares were infected with more than one bacterial species, confirmed on culture. Ferrer said 65.5% had both Gram- negative and Gram-positive bacteria pres- ent, which have structural or functional differences that make some drugs more effective against them than others. So she advised choosing a broad-spectrum anti- biotic that acts on both for these mares. Additionally, 59.8% of bacteria were multidrug resistant (MDR), especially Gram-negative bacteria (85.4%). Based on these findings, she recom- mended treating metritis with a com- bination of penicillin and amikacin or enrofloxacin. Other steps might include flushing the uterus daily (uterine lavage), administering the hormone oxytocin, giving non-steroidal anti-inflammatory drugs as needed, and adding domperi- done to stimulate lactation if necessary. The main metritis treatment goals are to control bacterial growth, evacuate uter- ine contents, and prevent complications. "Uterine culture should be incorporated into routine metritis management because it's important for monitoring MDR and guiding antimicrobial choice," she said. Broodmares Can Shed EHV-1 Vaginally Equine herpesvirus-1 (EHV-1) is a highly infectious disease that can cause respiratory and neurologic signs in adult horses, as well as abortion in broodmares. Even without clinical signs of disease or evidence of the virus in the blood (vire- mia), horses can shed the virus, spread- ing it via nasal discharge and aborted placental tissues and fluids. Veterinarians recently determined mares can shed the virus via the vagina, too, putting their foals and barn mates at risk of infection. Carina Cooper, DVM, a pathobiology PhD candidate at the University of Guelph's Ontario Veterinary College, in Canada, aimed to determine not only the prevalence of EHV-1 in healthy brood- mares but also the effects of EHV-1 vac- cination during pregnancy. She assessed 385 healthy broodmares from 45 farms, collecting blood samples and nasal and vaginal swabs every two months during the 2016-2017 breeding season. Cooper isolated EHV-1 DNA from 85% of the mares at least once and found that 69% of mares were shedding from the nose (33%) and/or vagina (55%). "To be clear, the test I was using was very sensitive," she said, "and so was detecting really low levels of viral DNA— below what is normally found with the commercially available tests." A mare's odds of testing positive were lower within two months after EHV-1 vaccination, but vaccination is probably not very useful in preventing mares from becoming latent carriers, said Cooper. "Mares had likely long before become infected," she said, theorizing that vac- cination was reducing viral activity in the blood but not shedding. Cooper's main take-home: "The virus can be found in the (healthy mare's) vagina and might be a bigger source of environmental contamination than previ- ously thought," she said. Uterine Tube Obstruction Treatments Vets typically only suspect uterine tube obstruction after ruling out other subfertility causes, and it's unclear how treating these rare presumed pathologies affects future fertility. So Stephanie Wal- bornn, DVM, Dipl. ACT, of Rood & Riddle Equine Hospital in Wellington, Florida, compared two treatment methods: ■ Applying prostaglandin E2 (PGE2, a hormone that causes the oviduct to relax) laparoscopically to the tube surface; and ■ Performing hysteroscopic hydrotuba- tion (passing an endoscope into the uterus, catheterizing the tube, and flushing it). Walbornn looked at records of 69 mares ages 4 to 22 that had been barren for one year for no determinable reason. Thir- teen of the 20 mares (65%) that received laparoscopic PGE2 application conceived, as did 35 of 49 (71%) that underwent ISTOCK.COM Mare Health & Fertility

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