Objective—To determine the onset, magnitude, and
duration of bronchodilation after administration of
aerosolized salmeterol xinafoate in horses with recurrent
Design—Randomized controlled study
Animals—6 horses with recurrent airway obstruction.
Procedure—Horses received aerosolized salmeterol
(210 µg) or no treatment, using a crossover design.
Salmeterol was administered, using a mask designed for
aerosol delivery in horses. Subjective rating of airway
obstruction (RAO), maximal change in pleural pressure
(ΔPplmax), and pulmonary resistance (RL) were determined
at baseline; 5, 15, and 30 minutes; and 1, 2, 4, 6,
8, 10, and 12 hours after administration of salmeterol and
in horses that did not receive treatment.
Results—The ΔPpl and RL were improved 15 minutes
through 6 hours after administration of salmeterol,
compared with values obtained from horses receiving
no treatment. The RAO was improved 15 minutes
through 2 hours after administration of salmeterol. The
maximal response to salmeterol was evident 30 to 60
minutes after administration and was characterized by
a 59 ± 19% decrease in ΔPpl and a 56 ± 13% decrease
in RL. The ΔPpl and RL were not different from baseline
values 8 hours after salmeterol administration.
Conclusions and Clinical Relevance—Duration of
action of salmeterol in these horses was approximately
6 hours. Maximal bronchodilation was somewhat
delayed (30 to 60 minutes), and the magnitude of
response was similar to that of short-acting β2-adrenergic
agonists. Salmeterol provides moderately sustained
bronchodilation in horses with recurrent airway
obstruction and may be an effective drug for long-term
control of this condition. (J Am Vet Med Assoc
Objective—To evaluate plasma epinephrine and
norepinephrine concentrations and serum cortisol
concentration in horses with colic and assess the
relationship of these variables with clinical signs,
routinely measured clinicopathologic variables, and
outcome in affected horses.
Design—Prospective observational study.
Animals—35 horses with colic.
Procedure—Blood samples were collected within 30
minutes of arrival at the veterinary hospital from horses
referred because of colic. Plasma and serum samples
were analyzed for cortisol, epinephrine, norepinephrine,
lactate, and electrolyte concentrations and acid-base
variables. Heart rate at admission and outcome (survival
or nonsurvival) were recorded. Univariate logistic
regression was used to calculate crude (unadjusted)
odds ratios and 95% confidence intervals.
Results—Of the 35 horses with colic, 26 survived.
Higher plasma epinephrine, plasma lactate, and
serum cortisol concentrations were significantly
associated with increased risk of nonsurvival, but
plasma norepinephrine concentration was not associated
with outcome. Plasma epinephrine concentration
was significantly correlated with heart rate
(r = 0.68), plasma lactate concentration (r = 0.87),
blood pH (r = –0.83), anion gap (r = 0.74), and base
excess (r = –0.81).
Conclusions and Clinical Relevance—The risk of
death appears to be greater in colic-affected horses with
high circulating concentrations of epinephrine and cortisol.
The correlation of epinephrine with other biochemical
markers of illness severity and with heart rate indicates
that the degree of sympathetic activation in horses
with colic can be inferred from routinely measured
variables. (J Am Vet Med Assoc 2005;227:276–280)
Objective—To evaluate clinical response, pulmonary
function, and adrenal gland response to incremental
doses of beclomethasone dipropionate in horses with
recurrent airway obstruction.
Animals—8 horses with recurrent airway obstruction.
Procedure—Horses randomly assigned to 4 groups
were treated twice daily via aerosol administration of
placebo or 500, 1,000, or 1,500 µg of beclomethasone
dipropionate in a crossover design with a 10-day
minimum washout period. Subjective assessment of
airway obstruction, serum cortisol concentration, and
maximum change in pleural pressure during tidal
breathing (ΔPplmax) were determined daily prior to
morning drug administration, and ΔPplmax was reevaluated
15 minutes after morning drug administration.
Pulmonary resistance and dynamic compliance were
determined at baseline and approximately 12 hours
after the final treatment.
Results—An immediate treatment effect was not
identified. Within 24 hours, ΔPplmax and airway
obstruction were lower in horses receiving
beclomethasone. Onset and magnitude of response
was similar among the 3 beclomethasone dose regimens.
Pulmonary resistance was improved only after
administration of all 3 doses of beclomethasone,
whereas dynamic compliance was improved after
administration of 1,000 µg and 1,500 µg of
beclomethasone. Reduction in serum cortisol concentration
occurred with all 3 beclomethasone dose
regimens; however, the magnitude of adrenal gland
suppression was greater in horses receiving 1,000 or
1,500 µg of beclomethasone.
Conclusions and Clinical Relevance—Low-dose
(500 µg) beclomethasone administration caused similar
improvement in pulmonary function, compared
with high-dose beclomethasone (1,000 and 1,500
µg), with the exception of dynamic compliance, and
caused less suppression of endogenous cortisol production.
(J Am Vet Med Assoc 2000;217:359–364)
Case Description—A 7-year-old Quarter Horse gelding used for unsanctioned racing was examined because of fever and anorexia.
Clinical Findings—Physical examination revealed fever, tachycardia, and tachypnea. Results of a CBC indicated anemia and mild thrombocytopenia. Results of microscopic examination of a blood smear indicated piroplasms in erythrocytes, consistent with Babesia spp. Regulatory authorities were contacted, and results of serologic testing at the National Veterinary Services Laboratories confirmed acute Babesia equi infection.
Treatment and Outcome—Equids on the home premises of the index horse were placed under quarantine. Those equids were tested for piroplasmosis, and 6 of 63 horses had positive results for B equi. Another horse that had previously been housed on the index premises also had positive results for B equi. Competent tick vectors for piroplasmosis organisms were not identified. All 8 horses with piroplasmosis were Quarter Horses that participated in unsanctioned racing and were trained by the same person. Two of the horses were illegally removed from the index premises; these 2 horses and the other horse with piroplasmosis that was previously housed on the index premises could not be found. The other 5 horses with piroplasmosis were euthanized. Investigators concluded that transmission of B equi among horses was most likely iatrogenic.
Clinical Relevance—The United States has been considered piroplasmosis free. However, veterinarians should consider piroplasmosis in horses with signalments and clinical signs similar to those of the index horse of this report. Regulatory authorities should be contacted regarding horses in which piroplasmosis is suspected.