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SUMMARY

Using an applanation tonometer, 5 replicate intraocular pressure (iop) measurements were obtained from each eye of 12 young, clinically normal, American alligators. Alligator length ranged from 46 to 117 cm, measured from snout to tail tip. All iop were recorded by a single observer at an ambient temperature of approximately 25 C, and ranged from 5 to 35 mm of Hg. Observer reliability was excellent (intraclass r = 0.93), and iop did not change over the ordered sequence of 5 replicate measurements/eye. Replicate iop measurements were, therefore, averaged in each eye for comparison between eyes of the same alligator. Left and right eye iop were highly correlated within individual alligators (r = 0.92), whereas the mean within-animal difference between left and right eye iop was not statistically significant (95% confidence interval [ci] for the left eye-right eye mean difference, −1.9 to 1.5 mm of Hg). Mean iop determined for 5 confirmed females and 3 confirmed males did not differ significantly between the sexes (95% ci for the male-female difference in means, −2.1 to 3.7 mm of Hg). Mean ± sem iop of 23.7 + 2.1 mm of Hg determined for 4 alligators < 50 cm long was significantly (P = 0.009) greater than mean iop of 11.6 + 0.5 mm of Hg determined for 8 alligators > 50 cm long (95% ci for the difference in means, 8.5 to 15.7 mm of Hg). In young alligators, the relation between body length and iop appears to be nonlinear, possibly with a negative exponent.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine the association between longitudinal bone growth and concentrations of growth hormone (GH) and insulin-like growth factor-I (IGF-I) in serum from prepubertal dogs.

Animals

6 male 14-week-old German Shepherd Dogs.

Procedure

Blood was obtained every 30 minutes for 14 consecutive days. Concentrations of GH and IGF-I in serum were determined, using a canine-specific radioimmunoassay and conventional radioimmunoassay after acid-ethanol extraction, respectively. Simultaneous biplanar radiography was performed daily to measure bone growth. Spectral analysis was used to estimate specific features of GH secretion during an extended period. Multiple linear regression with different lag times between independent and dependent variables was used to determine the strongest predictors of bone growth.

Results

The power spectra of GH concentrations in serum had a primary peak at a frequency of 0.02 cycles/h or a periodicity of 50 h/cycle. A significant determinant of longitudinal bone growth was a lag time of 1 day in concentration of GH in serum. The relationship between IGF-I concentration in serum and bone growth was not significant.

Conclusions

The primary frequency of GH secretion is outside the time frame of a single day and the concentration of GH in serum is a primary determinant of bone growth.

Clinical Relevance

A better understanding of the components of bone growth provide discernment to improved diagnosis and treatment of abnormal bone growth. (Am J Vet Res 1998;59:1608-1612)

Free access
in American Journal of Veterinary Research