Researchers at the University of Montreal used five mares with severe equine asthma (SEA, also called “heaves”) to determine whether estrus affected the severity of the condition.
In humans, studies completed in the 1980s showed that reproductive hormones can exacerbate asthma. Most studies showed a deterioration of symptoms, with an increase in emergency room admission rates just before or during menses.
The scientists were curious whether the same triggers applied to mares. The team kept the horses in a barn on wood shavings and fed them dry hay to trigger SEA symptoms. Once the mares were exhibiting respiratory effort at rest, researchers measured lung function and focused on respiratory function during two specific periods of the mare's cycle: the follicular phase and the luteal phase.
The follicular phase is the four- to eight-day period when mares are receptive to being bred. The luteal phase is after ovulation when a mare isn't receptive to a stallion.
The team found that there was slight improvement in lung function during the luteal phase of the estrous cycle. Though it is unclear exactly how hormones influence respiratory function, Dr. Sohpie Mainguy-Seers notes that the there may be sex hormone receptors in horse's lungs, so estrogen and progesterone could have direct effects on the lungs. Additionally, hormone receptors in the brain might influence control of breathing.
The team suggested that their study could lead to changes in how SEA mares are treated. If their findings are confirmed, a treatment regimen could be created for mares whose estrous cycle affects their respiratory signs.
Read more at EQUUS magazine.
The post Estrus And Equine Asthma: What’s The Link? appeared first on Horse Racing News | Paulick Report.
