Db. Tesarowski et al., PULMONARY-FUNCTION MEASUREMENTS DURING REPEATED ENVIRONMENTAL CHALLENGE OF HORSES WITH RECURRENT AIRWAY-OBSTRUCTION (HEAVES), American journal of veterinary research, 57(8), 1996, pp. 1214-1219
Objectives-To evaluate the degree of reproducibility in clinical varia
bles, blood gas measurements, and lung function variables, and the cha
nges in these variables caused by exposure to moldy hay in naturally s
ensitized and control horses. Procedure-The magnitude of variation in
arterial blood gas and pulmonary function measurements were evaluated
in a model of naturally acquired heaves. Horses with heaves and simila
rly aged control horses were studied prior to moldy hay challenge and
again after the horses with heaves manifested clinical signs oi airway
obstruction. This cycle of testing was repeated 3 times to determine
the variation of the before and after challenge measurements. Variable
s evaluated for repeatability included: clinical score; arterial O-2 a
nd CO2 tensions; pulmonary function variables, such as breathing rate
(f), tidal volumes, and flow rates; lung resistance (RL); dynamic comp
liance; and work of breathing (W-b). Results-Before challenge, signifi
cant differences observed between control horses and horses with heave
s included clinical score, expiratory flow rate at near-end expiration
, RL, and W-b. After exposure to moldy hay, variables measured in cont
rol horses were largely unchanged. However, in the afflicted horses, s
ignificant changes were observed for clinical score,arterial O-2 and C
O2 tensions, breathing; rate, peak tidal inspiratory and expiratory fl
ow rates, dynamic compliance, RL, and W-b, compared with prechallenge
values and with control horses' postchallenge values. Analysis of the
data revealed few statistically significant differences between repeat
s of challenges. Conclusion-Horses afflicted with heaves manifest air
way obstruction that can be measured in repeatable fashion.