The influence of hay steaming on clinical signs and airway immune response in severe asthmatic horses

ackground Avoidance of antigenic stimuli was found to significantly reverse airway obstruction of horses with severe equine asthma (sEA). To date, no published study investigated the influence of steaming hay on lower airway condition of sEA-affected horses. The objectives were to determine the clinical, cytological and cytokine respiratory responses of both sEA and control (CTL) horses experimentally exposed to steamed or dry hay. Results A cohort of 6 sEA horses and 6 CTL horses was involved in this field study. On day 0, both groups were fed with steamed hay for 5 consecutive days, followed by a wash-out period of 26 days prior to be fed with dry hay for 5 consecutive days. Investigations performed 2 days prior to and 5 days after each challenge included clinical score, tracheal mucus accumulation, and bronchoalveolar lavage fluid (BALF) cytology and cytokine mRNA expression. Feeding steamed hay significantly decreased its mould content (P < 0.001). Mucus score significantly increased when feeding dry hay (P = 0.01). No significant influence of challenge type was found on clinical score. Percentages of neutrophils (P < 0.001) as well as mRNA expression of IL-1β (P = 0.024), IL-6R (P = 0.021), IL-18 (P = 0.009) and IL-23 (P = 0.036) in BALF of sEA affected horses were significantly increased after both (steamed and dry hay) challenges. Relative mRNA expression of IL-1β, IL-6R and IL-23 in BALF were also significantly correlated to neutrophil percentages and both clinical and tracheal mucus score. Conclusions Steaming significantly decreased mould content but inconsistently influenced the respiratory response of sEA affected horses when fed hay. Based on BALF cytology and cytokine profiles, its relevance might be controversial as a non-medicinal therapy for sEA-affected horses

Cytological profiles of equine bronchoalveolar lavage fluid: a retrospective study

International audienc

Cytological profiles of equine bronchoalveolar lavage fluid: a retrospective study

International audienc

Profils cytologiques de liquide de lavage bronchoalvéolaire chez les chevaux: étude rétrospective (2013 – 2015)

International audienc

Profils cytologiques de liquide de lavage bronchoalvéolaire chez les chevaux : étude rétrospective (2013-2015).

National audienc

Comparaison du lavage trachéal et du lavage broncho-alvéolaire pour le diagnostic cytologique de l’hémorragie pulmonaire induite par l’exercice

National audienceIntroduction:Various methods are reported for diagnosis of exercise-induced pulmonary haemorrhage (EIPH). Cytological evaluation of airway samples is a sensitive method, but the correlation between tracheal wash (TW) and bronchoalveolar lavage fluid (BALF) findings for diagnosis of EIPH is unknown.The objective was to determine whether diagnosis of EIPH, using haemosiderophages/macrophages (H/M) ratio, differs when based on samples from TW and BALF collected concomitantly from the same racehorse.Methods:Prospective cross-sectional study on 102 Standardbred horses in active training. TW and BALF from each lung separately were collected from all horses at rest. Smears were stained with May-Grünwald-Giemsa (MGG) and H/M ratio calculated. Diagnostic cut-off values were set at 17% for individual (left and right) BALF and 9% for pooled BALF. H/M ratio in TW samples were scored as none (0%), occasional (50%).Results:In BALF, 21 horses met the cytological inclusion criteria for EIPH diagnosis from individual and/or pooled samples. In TW, 20 horses had occasional proportions of haemosiderophages, and respectively 9, 1 and 3 horses had small, moderate and large proportions. Poor correlations between TW and respectively pooled, left and right BALF were found for H/M ratio. Among the 13 horses with at least small proportions of haemosiderophages in TW, 8 (61.5%) had no cytological evidence of EIPH in any BALF.Conclusion and clinical relevance:No association between TW and BALF was found for the cytological diagnosis of EIPH. A large number of horses has cytological evidence of pulmonary bleeding in BALF with none or occasional proportions of haemosiderophages in TW. In addition, finding small to large proportions of haemosiderophages in TW is mostly not associated with evidence of pulmonary haemorrhage in BALF. Based on H/M ratio, BALF remains the sample of choice for cytological diagnosis of EIPH