The Dynamics of Circulating Immune Complexes in Horses with Severe Equine Asthma

SIMPLE SUMMARY: Equine asthma syndrome is a cost-consuming equine respiratory disease of the lower airways in horses. Non-invasive biomarkers from blood or urine are sought. The aim of this study was to assess the circulating immune complexes (CICs) during the exacerbation and remission of an asthma episode—with and without additional treatment and the potential usefulness of CIC levels in the diagnosis, monitoring, and treatment progression. The control group, asthma group, and treated asthma group each contained six horses. The horses were kept in a dusty environment for seven days and then moved to an asthma-friendly environment for over three weeks (the treated group received injections of glucocorticoids). Blood was collected at baseline and on the 1st, 2nd, 3rd, 7th, 14th and 30th days. CICs measured in the time points did not show statistical differences. When CICs were analysed within the groups, there was a significant decrease in CIC in the treated group and a significant increase in CIC in the non-treated group on day 30. CIC did not support the diagnosis procedure of equine asthma syndrome, although it may help in monitoring patients with and without treatment. To the best of the authors’ knowledge, this is the first study to analyse the dynamics of CIC in equine asthma patients during an environmental challenge, remission, and treatment. ABSTRACT: Non-invasive diagnostic biomarkers of equine asthma syndrome (EAS) from blood or urine are sought. The aim of this study was to assess the absorbance of circulating immune complexes (CICs) during the exacerbation, remission, and treatment of an asthma episode and assess the potential usefulness of CIC levels in the diagnosis and monitoring of the disease. The control group, asthma group, and treated asthma group each contained six horses. Following an initial examination and group classification, the horses were kept in a dusty environment for seven days and then moved to an asthma-friendly environment for three weeks (the treated group received injections of glucocorticoids). Blood was collected at baseline and on the 1st, 2nd, 3rd, 7th, 14th and 30th days. CIC was measured using the modified Haskova method. The time points did not show significant statistical differences. There was a significant decrease in CIC in the treated group, and a significant increase in CIC in the non-treated group on day 30. CIC did not support the EAS diagnosis, although it may help in monitoring patients. To the best of the authors’ knowledge, this is the first study to analyse the dynamics of CIC during environmental challenge, remission, and treatment.