A mild winter with little snow, a warm and early spring–so far the year has been kind to horses (and people) in many northern states. But the good weather may have some unwanted effects on horse health, says Michigan State University Extension veterinarian Judy Marteniuk, DVM. Here are three risks to watch for:

The mild winter in most parts of North America have allowed disease-carrying insects, such as mosquitoes, to get a head start on the season.

• Disease-carrying insects. Early spring warmth gave insects a head start on the season, increasing the danger of insect-borne diseases like Lyme disease, carried by black-legged ticks, and West Nile virus, Eastern equine encephalitis and Western equine encephalitis, carried by mosquitoes. These insects were out and about, breeding and biting, weeks ahead of schedule. (New research also suggests that mild winters may move up the date at which disease-carrying mosquitoes shift from ?biting birds, their early season prey, to horses, people and other ?mammals.) To counter the threat, many horses were vaccinated against West Nile, EEE and WEE a few weeks earlier than usual. “The effect of the vaccinations lasts six to eight months,” Dr. Marteniuk says, “so these horses may need boosters in the fall if the mild weather continues.” Follow your veterinarian’s guidance.
• Internal parasites. The mild winter may have increased the risks from strongyles and other internal parasites. Adult strongyles (large or small) live in your horse’s large intestine and produce eggs that are passed in manure. In pastures (or wherever they land) the eggs hatch into infective larvae that horses ingest. Warmer-than-usual temperatures may have allowed more eggs to survive winter and hatch out early, Dr. Marteniuk says. “You don’t necessarily need to deworm more, but monitor closely to be sure parasites are under control,” she says. “Fecal evaluations should always be part of your program, and you may want to do an extra one this year.”
• Sand colic. Cases of sand colic have been higher than normal in her area this spring, Dr. Marteniuk reports. Lack of snow cover meant that turned-out horses nibbling for forage (or fed on the ground) took in quantities of sandy soil, which can build up in the gut and irritate the intestinal ?lining. Horses should be kept off barren, sandy soil and fed on mats to reduce the risk, she advises. Psyllium supplements, fed according to the manufacturer’s directions, may help move sand through the gut. But don’t expect quick results, Dr. Marteniuk says: “It can take weeks or months for sand to be moved out of the ?digestive tract, depending on the amount present.”

The Big Dry
Meanwhile, a prolonged drought has parched areas from Arizona east to North Carolina and northern Florida, and from Kansas south into Mexico. Last year Texas, in the heart of the stricken region, had the hottest and driest summer and the most destructive drought in its history, according to state officials. Pastures browned and stock tanks dried up. This year spring rains brought relief across parts of the Great Plains and along the Gulf Coast, especially in southeast Kansas, Oklahoma and northern and central Texas. But drought conditions persist in much of the Southwest and parts of the Southeast, and horse owners are dealing with the effects.

The drought has sharply curtailed hay production. As local supplies ran out last year, hay was trucked to Texas from as far away as Oregon, and prices shot up. Many horse owners turned to hay cubes, alfalfa pellets, beet pulp and other fiber sources to stretch their limited stores. This year, supplies have remained tight and prices high. In March, horse hay was listed for $10 to $20 per small bale and $90 to $100 per 4-by-5-foot round bale on the Texas Department of Agriculture’s Hay Hotline website.

The number of horses auctioned off, turned over to rescues or simply abandoned has risen in the drought-stricken regions, according to news reports. The drought was also said to be a factor in increased cases of some equine diseases, such as pigeon fever (a bacterial infection that causes abscesses, often in the chest and abdomen).

Scientists believe the weather phenomenon called La Ni?a was a major factor in the southern drought, and the National Weather Service’s Climate Prediction Center expects the current La Ni?a to end by summer. But many other forces drive weather patterns. For example, scientists report that rapid warming in the Arctic is altering the path of the jet stream, the major west-to-east air current over North America. That trend may make weird weather the new normal.