Last Updated on April 5, 2022 by Allison Price
Researchers in Canada have reported that the estrus cycle may play a role in lung function in severe asthma-afflicted mares.
Researchers at the University of Montreal wrote in the journal Animals that asthma severity and development can be affected by the estrus cycle.
Asthma is more common among boys than it is in girls in childhood. However, this tendency reverses in puberty suggesting that there may be a sex-hormone-related effect.
It is not known if the same effect occurs with equine asthma.
Horses with severe asthma can have difficulty breathing even when they are at rest. Although it is treatable by medication and management, it remains incurable.
Although hay feeding and stabling can make the condition worse sometimes, there are other factors that could be contributing to the problem.
About 14% of adult horses with severe asthma are in temperate environments. Although a predisposition has been observed in females, it is not a common finding.
Sophie Mainguy–Seers MouhamadouDiaw, Jean-Pierre Lavoie and Jean-Pierre Lavoie set about to assess the effect of the estrus cycle upon airway dysfunction in five horses with severe asthma. They assessed their lung function during the luteal and follicular phases of the reproductive cycles.
During the reproductive cycle, whole breath, inspiratory and expiratory resistances, and reactance were all compared.
The study revealed a significant reduction in inspiratory obstruction during the luteal phase. The study also showed an improvement in the rate of reaction.
The correlation between lung function parameters and progesterone levels was found to be significant. This suggests that horses may have asthma from sex hormones.
The study team stated that “the fluctuation in airway dysfunction during an estrus cycle is notable as deterioration could possibly be prevented by horse owners or veterinarians.”
They said that further research is needed to determine the effects of sexhormones on asthma in horses and humans.
“Further research is needed to determine if the horse species could be used as a model to assess the effects of sexhormones on asthma.
“Indeed the reproductive physiology for mares and women are similar in many aspects, such as the prolonged follicular period and the monovulation [release a single ovum every cycle].
“The horses’ ability to evaluate their reproductive tracts and their long life expectancy are two additional benefits.”
They suggested that future studies should investigate the location and proportion of estrogen receptors and progesterone in the equine respiratory system and the effects of these hormones on the biology and function of the airway cells.