J.E. Dinger

Viable Borrelia burgdorferi in the urine of two clinically normal horses

Diagnosticiansshould be aware of the possibilities of these concurrent viralinfections in raccoons with neurologic disorders.Acknowledgements We thank G. Moser, B. Lehman, andS. Hindman for technical assistance. This work was sup-ported by grants from the Pennsylvania Department of Ag-riculture and the Laboratory of Large Animal Pathology,University of Pennsylvania.References

Effect of controlled exercise on semen characteristics in two-year-old stallions☆

A two-phase study was conducted to evaluate the effect of controlled daily exercise on semen characteristics of 2-yr-old stallions. Eight nonexercised, sexually inexperienced 2-year-old Morgan stallions were randomly assigned to one of two groups. In Phase 1, four stallions were randomly assigned to receive daily controlled exercise for 16 wk. In Phase 2, these stallions were confined to box stalls for 16 wk. The remaining four stallions were confined to box stalls for 16 wk during Phase 1 and received daily controlled exercise for 16 wk during Phase 2. Individual semen collections were obtained from all stallions every 14 days. Daily sperm output (DSO) was determined by daily semen collections for seven consecutive days on Wk 0, 8, 16, 24, and 32. Mean DSO (10(9)) in Phase 1 was 3.52+/-.62 and 2.79+/-.75 for Wk O and 3.12+/-.39 and 2.61+/-.68 for Wk 16 for exercised and nonexercised stallions, respectively. Mean DSO (10(9)) in Phase 2 was 2.61+/-.68 and 3.12+/-.39 for Wk 16 and 2.48+/-.69 and 3.95+/-.51 for Wk 32 for exercised and nonexercised stallions, respectively. No effect (P>.05) of treatment was observed in either phase when parameters of spermatozoa concentration, total spermatozoa per ejaculate, DSO, total volume, gel-free volume, gel volume, percentage motility, percentage live, pH, and percentage normal were measured and analyzed.

Effects of unilateral castration on morphologic characteristics of the testis in one-, two-, and three-year-old stallions☆

The effects of unilateral castration on testicular compensatory hypertrophy were measured in 12 Morgan stallions, four each at one, two, and three years of age. They were randomized within age to intact (IN) or unilaterally castrated (UC) groups. Allotment and surgery were in January 1983 and total castration was in June 1983, 150 d after unilateral castration. Testis weight increased linearly with age (P < 0.01) and was increased by unilateral castration (P < 0.07). Epididymal weight also increased linearly with age (P < 0.05) and was heavier in UC animals (P = 0.15). Tubule diameter (P < 0.10) and epithelial height (P < 0.03) were greater in UC than in IN stallions. In conclusion, testes of stallions underwent compensatory hypertrophy after unilateral castration.

The effects of cervical dilation on plasma PGFM, progesterone and the duration of luteal function in diestrous mares

Transcervical diagnostic techniques may alter the length of the equine estrous cycle and affect subsequent luteal function. Therefore, nine mares were used to determine the effect of cervical dilation on plasma 13, 14-dihydro, 15-keto-prostaglandin F(2) (PGFM), progesterone (P(4)) and posttreatment duration of luteal function. Mares were given a daily score of 0 to 4 based on sexual receptivity. Five days following the end of receptivity, mares were randomly assigned to one of three, 3 x 3 latin squares. Control mares received no cervical dilation. Cervically stimulated mares recieved cervical dilation for 60 sec. Cervically stimulated plus inhibitor mares were dilated similarly to cervically stimulated mares, but received a prostaglandin synthetase inhibitor 30 min prior to treatment. Each mare completed all three treatments in three consecutive estrous cycles. Plasma PGFM and P(4) were determined by RIA. Plasma PGFM was lower (P<0.05) in cervically stimulated plus inhibitor than control and cervically stimulated mares. In addition, plasma P(4) was lower (P<0.10) in cervically stimulated plus inhibitor than in control and cervically stimulated mares. Luteal function following treatments did not differ. These data indicate that neither plasma PGFM and P(4) nor the duration of luteal function were affected by cervical dilation. However, administration of a prostaglandin synthetase inhibitor prior to cervical dilation decreased plasma PGFM and P(4) concentrations.

Suspected clinical Lyme disease in horses: Serological and antigen testing differences between clinically ill and clinically normal horses from an endemic region

Abstract Equine Lyme disease is difficult to diagnose because of its nonspecific clinical signs and the high incidence of subclinical infection in endemic regions. In this study we compared serology, antigen presence, hematology, blood chemistries and clinical presentation of 22 horses from a highly endemic region that were clinically diagnosed with Lyme disease to that of 21 clinically normal horses from the same region. We found that horses clinically diagnosed with Lyme disease were more likely to have Borrelia burgdorferi spirochetal DNA in their blood and urine, have a higher percentage of positive immunoblots containing antibodies to certain B. burgdorferi proteins, and tend to have higher ELISA titers than healthy horses from the same region. These results may help to improve diagnostic testing for equine Lyme disease.

Effects of unilateral castration on serum luteinizing hormone, follicle stimulating hormone, and testosterone concentrations in one-, two-, and three-year-old stallions.

The endocrine control of compensatory hypertrophy was investigated in 12 Morgan stallions, four each at one, two and three years of age. Half were assigned to be unilaterally castrated (UC) in January and half to remain intact (IN). Nine blood samples were taken from each stallion at half-hour intervals 30, 90, and 150 d after unilateral castration for radioimmunoassay of serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), and testosterone. Mean serum LH concentration was greater (P<0.06) in UC than IN stallions; however, the difference was greatest at 30 d and least at 150 d. Serum LH was greater (P<0.01) in two- and three-year-olds than in one-year-olds. The mean log(10) for serum FSH concentration was greater (P<0.06) in UC than IN stallions. Mean serum testosterone concentrations were similar in UC and IN stallions for all sample days, suggesting that the single testes of the UC stallions produced as much testosterone as the two testes of the IN stallions. Two- and three-year-old stallions had greater (P<0.01) serum testosterone than one-year-old stallions. Unilateral castration of stallions was associated with a significant increase in serum LH and FSH concentrations and, perhaps, higher intratesticular testosterone, which may explain, in part, the compensatory hypertrophy noted in the remaining testis.

Prediction of daily sperm output in stallions

Ten sexually inexperienced Thoroughbred stallions, ranging in age from 4 to 7 yr, were used to determine the relationship between available extra-gonadal reserves (AEGR) and daily sperm output (DSO). Ejaculates were obtained during the months of June through December. Each stallion was ejaculated at 0700, 0800, and 1700 h on Day 1 and 0700, 1200, and 1700 h on Days 2 and 3. A single ejaculate was collected at 0700 h on Days 4 through 7. DSO was calculated by averaging the total spermatozoa obtained on Days 5, 6, and 7. A minimum of 14 d was allotted to each stallion between trials to allow replenishment of AEGR. Weekly trials were classified as 1) primary: ejaculates taken from sexually inexperienced stallions; 2) normal: all weekly ejaculated in which the total spermatozoa in the second ejaculate (0800 h on Day 1) divided by the total spermatozoa in the first ejaculate (0700 h on Day 1) yielded percentages >20 and <70%; and 3) all: all weekly trials. Regression analysis yielded an equation of estimated DSO=0.18 (total spermatozoa in first ejaculate) + 0.93. Measured DSO, mean of total spermatozoa collected on Days 5, 6, and 7, divided by total spermatozoa in the first ejaculate of normal weekly trials averaged 27.5+/-1.9%. When 27.5% was multiplied by the total spermatozoa found in the first ejaculate (0700 h on Day 1) in primary, normal, and all trials, correlation coefficients between measured and estimated DSOs of 0.95, 0.95, and 0.92, respectively, were obtained. In conclusion, there appears to be a relatively stable relationship between AEGR and DSO in Thoroughbred stallions aged 4 to 7 yr. This relationship allowed a famrly accurate (82%) estimation of DSO when the total number of spermatozoa found in the first ejaculate of sexually rested stallions is multiplied by 27.5%.

Plasma progestogen levels in pregnant mares following administration of exogenous progesterone

Twelve pregnant mares were used in a switchback design with two groups of six mares each. On day 255 of gestation, group A was administered repository progesterone (250 mg, IM) and group B progesterone in sesame oil (250 mg, IM). Jugular vein plasma was taken 15 min pre-injection and post-injection at 30 min, 1, 3, 6, 9, 12, and 24 hours. Additional samples were taken on days 2, 3, 4, 6, and 8. Both groups were then assigned to the opposite treatment on day 270 of gestation. Concentrations of plasma progestogens after injection with progesterone in sesame oil were not different (P>.05) from values obtained using repository progesterone through the 8 days studied. Mean progestogen concentrations after injection of progesterone in sesame oil were, however, consistently higher through 48 hr than those given repository progesterone. Concentrations of progestogens were not different (P>.05) from pre-injection concentrations by day 6 post-injection using either vehicle.

Vaginal and cervical mucus ferning as a method of detecting estrus in mares

Abstract A two-phase study was conducted to evaluate cervical and vaginal mucus ferning as a method for detecting estrus in mares. The ten mares utilized in Phase A were teased every third day while in diestrus and daily during estrus over a 70 day period. Cervical dilation, cervical mucus ferning and vaginal mucus ferning were monitored following teasing. The correlations between teasing and cervical dilation, cervical mucus ferning, and vaginal mucus ferning were: .44 (P The six mares in Phase B were given PGF2α on days 0 and 14, and HCG on days 6 and 20. Cervical dilation, as determined by rectal palpation, and vaginal mucus, taken by suction and swab techniques, were monitored on days 17 through 30 prior to daily teasing. The correlations between teasing and cervical dilation and vaginal mucus ferning, obtained by suction technique, were .11 (P>.05) and .23 (P>.05), respectively. Vaginal mucus samples obtained using the suction method more effectively (P