Objective—To determine the relationship between
plasma β-endorphin (EN) concentrations and exercise
intensity and duration in horses.
Animals—8 mares with a mean age of 6 years
(range, 3 to 13 years) and mean body weight of 450 kg.
Procedure—Horses were exercised for 20 minutes
at 60% of maximal oxygen consumption (O2max)
and to fatigue at 95% O2max. Plasma EN concentrations
were determined before exercise, after a 10-
minute warmup period, after 5, 10, 15, and 20 minutes
at 60% O2max or at the point of fatigue (95%
O2max), and at regular intervals after exercise.
Glucose concentrations were determined at the
same times EN concentrations were measured.
Plasma lactate concentration was measured 5 minutes
Results—Maximum EN values were recorded 0 to
45 minutes after horses completed each test.
Significant time and intensity effects on EN concentrations
were detected. Concentrations were significantly
higher following exercise at 95% O2max,
compared with those after 20 minutes of exercise at
60% O2max (605.2 ± 140.6 vs 312.3 ± 53.1 pg/ml).
Plasma EN concentration was not related to lactate
concentration and was significantly but weakly correlated
with glucose concentration for exercise at
both intensities (r = 0.21 and 0.30 for 60 and 95%
Conclusions and Clinical Relevance—A critical
exercise threshold exists for EN concentration in
horses, which is 60% O2max or less and is related
to exercise intensity and duration. Even under conditions
of controlled exercise there may be considerable
differences in EN concentrations between
horses. This makes the value of comparing horses
on the basis of their EN concentration questionable.
(Am J Vet Res 2000;61:969–973)
Procedure—Cats were randomly assigned to 3
groups of 6: control, tenectomy, and onychectomy.
Jugular catheters were placed the day prior to
surgery. All surgeries were performed by the same
surgeon, and all observations were made by the
same blinded trained observer. One hour prior to
surgery and at assigned intervals for 36 hours after
surgery, heart rate, respiratory rate, and rectal temperature
were measured. Scores were assigned for 3
interaction responses, including response to palpation,
by use of simple descriptive scales, and to 2 pain
assessments by use of visual analogue scales. Blood
was collected to measure plasma β-endorphin and
cortisol concentrations. Butorphanol was administered
to all cats before surgery and to any cat subjectively
assessed to be experiencing pain after surgery.
Results—Only visual analogue scale scores and
response to palpation scores differed significantly
between control and surgical groups.
Conclusions and Clinical Relevance—Determination
of the presence of pain in cats can be made
on the basis of observation and interaction by a
trained observer. Physiologic measurements, including
plasma cortisol and β-endorphin concentrations,
did not differentiate between control cats and cats
that underwent surgery. (J Am Vet Med Assoc 2000;
Objective—To determine the effect of finasteride on
programmed cell death (apoptosis) of prostatic cells
during prostatic involution in dogs with benign prostatic
Animals—9 dogs with BPH.
Procedure—Dogs were randomly assigned to treatment
or control groups. Treatment dogs (n = 5) were
administered finasteride (0.1 to 0.5 mg/kg, PO, q 24
h) for 16 weeks, whereas the 4 control dogs were
administered an inert compound. Prostatic cells from
the prostatic fluid portion of the ejaculate of treatment
and control dogs were obtained before and 1, 2,
3, 4, 8, and 16 weeks after initiation of treatment.
Cells were concentrated by use of centrifugation.
Prostatic cells were examined for indications of apoptosis
by use of a terminal deoxyribonucleotidyl transferase-
mediated deoxyuracil triphosphate nick-end
labeling technique. After receiving the inert compound
for 16 weeks, the 4 control dogs were administered
finasteride for 16 weeks, and evaluations
Results—Percentage of apoptotic prostatic cells in
ejaculated prostatic fluid of treatment dogs increased
significantly (from 9% before treatment to 33, 31, 26,
and 27% after 1, 2, 3, and 8 weeks of treatment,
respectively). There was no significant change in percentage
of apoptotic prostatic cells in the ejaculated
prostatic fluid of control dogs.
Conclusions and Clinical Relevance—Finasterideinduced
prostatic involution appears to be via apoptosis
in dogs with BPH. Finasteride treatment of dogs
with BPH causes prostatic involution by apoptosis
rather than necrosis. (Am J Vet Res 2002;63:495–498)
Objective—To determine the effect of the 5α-reductase
inhibitor finasteride on prostatic diameter and
volume, semen quality, and serum dihydrotestosterone
(DHT) and testosterone concentrations in dogs
with spontaneous benign prostatic hypertrophy
Design—Double-blind placebo-controlled trial.
Animals—9 dogs with BPH.
Procedure—Five dogs were treated with finasteride
for 16 weeks (0.1 to 0.5 mg/kg [0.05 to 0.23 mg/lb] of
body weight, PO, q 24 h); the other 4 received a
placebo. Prostatic diameter, measured radiographically,
prostatic volume, measured ultrasonographically,
semen quality, and serum DHT and testosterone concentrations
were evaluated before and during treatment.
After receiving the placebo for 16 weeks, the 4
control dogs were treated with finasteride for 16
weeks, and evaluations were repeated.
Results—Finasteride significantly decreased prostatic
diameter (mean percentage decrease, 20%), prostatic
volume (mean percentage decrease, 43%),
and serum DHT concentration (mean percentage
decrease, 58%). Finasteride decreased semen volume
but did not adversely effect semen quality or
serum testosterone concentration. No adverse
effects were reported by owners of dogs in the
Conclusions and Clinical Relevance—Results suggest
that finasteride can be used to reduce prostatic
size in dogs with BPH without adversely affecting
semen quality or serum testosterone concentration.
(J Am Vet Med Assoc 2001;218:1275–1280)