Effect of tracheal mucus and tracheal cytology on racing performance in Thoroughbred racehorses

Abstract

Summary Reason for performing study: Accumulations of mucus within the trachea are often found during endoscopic examinations of the airways of poorly performing racehorses, but the clinical importance of this finding is unknown. Objectives: To determine the effect of tracheal mucus, pharyngeal lymphoid hyperplasia (PLH) and cytological indices of tracheal aspirate on racing performance in Thoroughbred horses assessed by race place and whether the horse was raced. Methods: Endoscopic examination of the nasopharynx, larynx and trachea was performed, and a tracheal aspirate obtained monthly at Thistledown racetrack from April to December, 2002 and 2003. Horses received a score of 0–4 for the degree of PLH and 0–4 for the amount of mucus visible in the trachea. The tracheal aspirate was assessed for turbidity, and total and differential cell counts. Generalised estimating equations models were used as repeated measures models for each risk factor and the level of association assessed through the risk factor's P value in the model. Results: Moderate to severe tracheal mucus (2–4) was a risk factor for poor racing performance. There was no association between degree of PLH, cell counts or turbidity of tracheal wash fluid and racing performance. However, horses that raced had higher total neutrophil counts in tracheal wash aspirates than horses that did not race. Conclusions: Grades 2–4 tracheal mucus should be considered a potential cause of poor racing performance in Thoroughbred horses. Clinical relevance: Because moderate to severe tracheal mucus accumulation, and not increased tracheal neutrophils, was a risk factor for poor racing performance, functionally significant airway inflammation may best be confirmed by the presence of mucus rather than increased number of neutrophils in the trachea.

Mineral supplement with pre- and probiotic improves respiratory immune status in yearling racing Thoroughbred horses: preliminary results

“…However, increased amounts of tracheal mucus are considered a clinical sign of airway inflammation. For the racehorses, it has been noted that a TM grade of 2 or higher interferes with the pulmonary function of gas exchange (HOLCOMBE et al, 2006). As the amount of TM did not increase for the TG, it was considered an important finding because it corroborated with the lower grade of PLH in this group during M1.…”

Clinical Approach to Commonly Encountered Problems

“…247 Normal horses tend to be either grade 0 or 1, whereas those with equine asthma are 2 to 5. 232,[249][250][251] Diagnostic Imaging. 232,[249][250][251] Diagnostic Imaging.…”

Evidência De Hemorragia Pulmonar Induzida Pelo Exercício Em Cavalos De Salto De 1,00 M – 1,20 M

“…Considera-se, como evento fisiopatológico para a HPIE, a ruptura dos capilares pulmonares (falência pulmonar capilar) devido ao aumento da pressão transmural através do capilar, gerada tanto pelo aumento da pressão arterial pulmonar como pelas pressões pleurais bastante negativas (Holcombe, 2006). Contudo, apesar de aceitar-se que são requeridas pressões elevadas para que ocorra a falência dos capilares pulmonares (West e Mathieu-Costello, 1994), cavalos que realizaram exercício submáximo também apresentaram HPIE (Epp et al, 2006;Viccino, 2007), constituindo um dilema para o entendimento da fisiopatologia da HPIE (West, 2000).…”