Spring has sprung, the grass has turned green seemingly overnight, and already winter hairs are flying freely and any sign of a horse’s ribs showing are rapidly
disappearing.
Horses usually remain healthy during the winter months as long as they have plenty of good hay and water. However, when the weather starts to warm up, disease problems become much more common, warned Dr, John Harris at his highly-modern Harris Equine Hospital in Grand Junction, Colo.
During the warm months, respiratory viruses such as influenza and rhinopneumonitis prevail, with epidemics of both often common.
Longer, warmer days and green grass stimulate hormonal activity, so more injuries occur due to horses running into fences. Tetanus is always a concern whenever a full
thickness laceration through the skin occurs.
Mosquitoes transmit sleeping sickness or encephalitis, so it is a concern during the warmer months also. Potomac horse fever is a disease that has been diagnosed in some areas. Ticks are thought to be involved in transmitting the disease, which is seen mostly in the warmer months.
“It is evident the optimum time to vaccinate is springtime so horses will have the highest possible immunity during the peak exposure period,” Harris advised.
Vaccines for the previously mentioned diseases are available individually or in various
combinations, he pointed out.
“If you vaccinate for tetanus and encephalitis in the springtime, the immunity should protect until the next spring,” Harris said. “The respiratory virus vaccines such as flu
and rhino may need to be boosted a few times in a year to maintain a strong enough immunity to withstand the challenge of an epidemic.
“Traveling or show horses should be revaccinated for flu and rhino at two-month intervals,” he added.
If mares are vaccinated one to two months before foaling, the foal receives protective
antibodies when it first nurses the mare and gets the colostrum.
Some horses have antibodies against the causative organisms of Potomac horse fever; therefore most people choose not to use a vaccine, but it is available, Harris
noted.
Deworming should be done regularly year round, not just in the springtime. “Spring is an excellent time to deworm for stomach bots since some bots mature in the stomach later than others and a winter time deworming may not have killed all of them,” Harris related.
Special attention should be paid to strogyle or bloodworm control in the spring, because bloodworms multiply rapidly when the green grass starts to appear. “A horse,
which has not been dewormed, can pass up to 25 million bloodworm eggs per day,”
Harris emphasized.
Invermectin was recommended for bot and bloodworm control. “Deworming by passing a stomach tube and using a combination of dewormers is also a good method of worm control,” Harris suggested.
Ticks and lice are often seen on horses in springtime. “Ivermectin is also helpful in some cases where bloodsucking parasites are involved. In the case of biting parasites,
topical insecticides are necessary,” Harris qualified. “Care must be used to select an insecticide that is safe for use on horses.”
Dental problems do not just occur in springtime, but most horses are going into their season of heavy usage. “Correction of small problems such as filing sharp points on the inside edge of the upper molars can mean the difference between a successful
season or one of head throwing, bit chewing, and fighting.
“Some dental problems can prevent the horse from maintaining his optimum body weight and condition,” Harris described. “Horses with malocclusions of incisors or broken off incisors may not be able to maintain body weight on pasture. They will often require supplemental feeding, such as additional hay or cubed feed.”
Colic is a year-round problem, but seems to be more common in springtime. “This may be due to a variety of reasons, including foaling, weather changes, green grass and weeds being available for feed, depletion of sources of good quality hay, and
increased incidences of internal parasites,” the veterinarian calculated.
“Prevention includes selecting quality hay, feeding small amounts several times a day, rather than large amounts twice daily, and regular deworming,” he confirmed
In broodmares, the amount of hay should be reduced and grain increased to reduce bulk in the large intestines during the final two weeks prior to foaling, Harris explained.
“Horses are expensive animals to buy and maintain. The time and money spent on prevention often can eliminate disease or death loss, which can be economically and
emotionally devastating,”Harris concluded.
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