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- Author or Editor: Patrick M. McCue x
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Abstract
Objective—To validate a turbidimetric immunoassay (TIA) for measurement of plasma IgG concentrations in foals.
Animals—36 foals.
Procedures—Blood samples were collected from foals before suckling and at 12 and 24 to 36 hours after birth. Plasma IgG concentrations were determined via a commercial single radial immunodiffusion (RID) assay. By use of goat anti-equine IgG antiserum and a spectrophotometer, a TIA was developed to measure plasma and serum IgG concentrations; the percentage light transmission was calibrated against RID assay–determined IgG concentrations. Assay repeatability and effects of serial dilution, sample type, and ambient temperature on assay results were evaluated.
Results—Serial dilution of plasma samples from foals 12 and 24 to 36 hours of age with presuckle plasma yielded percentage light transmission results that were highly inversely correlated (r = −0.95) with IgG concentrations determined via RID assay. Measurements of IgG in plasma and serum samples via TIA did not differ. When samples were assayed multiple times, the coefficient of variation was < 5.0%. Ambient temperature did not affect TIA results. At IgG concentrations of 400 and 800 mg/dL, TIA sensitivity was > 90%; specificity was 99.1% and 70.5%, respectively; and positive and negative predictive values were 98.1% and 71.5%, respectively, and 96.4% and 91.1%, respectively.
Conclusion and Clinical Relevance—Plasma IgG concentrations in foals determined via the TIA and RID assay were highly correlated. The TIA rapidly yielded quantitative results and would be useful in clinical situations where intervention decisions are time dependent.
Abstract
Objective—To evaluate gonadotropin secretion and ovarian function after administration of deslorelin acetate to induce ovulation in mares.
Design—Randomized controlled trial.
Animals—16 healthy mares with normal estrous cycles.
Procedure—8 control mares were allowed to ovulate spontaneously, whereas 8 study mares received deslorelin to induce ovulation when an ovarian follicle > 35 mm in diameter was detected. Follicle development and serum concentrations of gonadotropins were monitored daily during 1 estrous cycle. Pituitary responsiveness to administration of gonadotropinreleasing hormone (GnRH) was evaluated 10 days after initial ovulation.
Results—Interovulatory intervals of mares treated with deslorelin (mean ± SD, 25.6 ± 2.6 days) were longer than those of control mares (22.9 ± 1.8 days). Diameter of the largest follicle was significantly smaller during 2 days of the diestrous period after ovulation in deslorelin-treated mares than in control mares. Concentrations of follicle-stimulating hormone (FSH) were lower in deslorelin-treated mares on days 5 through 14 than in control mares. Concentrations of luteinizing hormone were not different between groups during most of the cycle. Gonadotropin release in response to administration of GnRH was lower in mares treated with deslorelin acetate than in control mares.
Conclusions and Clinical Relevance—Administration of deslorelin was associated with reduction in circulating concentrations of FSH and gonadotropin response to administration of GnRH during the estrous cycle. Low concentration of FSH in treated mares may lead to delayed follicular development and an increased interovulatory interval. (J Am Vet Med Assoc 2001;218:749–752)
Abstract
Case Description—An 11-year-old Quarter Horse stallion was admitted for intermittent hemospermia of 4 years' duration.
Clinical Findings—A linear vertical defect had been detected endoscopically following multiple episodes of hemospermia on the caudodorsal convex surface of the urethra at the level of the ischial arch.
Treatment and Outcome—When sexual rest alone did not result in complete healing of the urethral defect, a subischial urethrotomy and buccal mucosal urethroplasty were performed. The surgical site healed without complication. Four months of sexual rest was recommended after surgery. Repeat endoscopy at 4 months allowed inspection of the urethral graft site. Following endoscopic examination, resumption of semen collection was recommended on the basis of the apparent healing at the urethral defect site. Hemospermia did not reoccur following surgical repair.
Clinical Relevance—Buccal mucosal urethroplasty resulted in a favorable outcome in a stallion with recurrent hemospermia. Buccal mucosal urethroplasty may be a useful surgical option in stallions that have hemospermia secondary to a urethral defect and do not heal with sexual rest alone.
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Laparoscopic castration of cryptorchid or hemicastrated horses is a viable surgical technique; however, transection of the spermatic chord to induce avascular necrosis of testicular tissue that is left in place can result in revascularization with subsequent production of testosterone and stallion-like behavior.
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Endocrine tests, such as determination of testosterone concentration and the human chorionic gonadotropin response test, can be used to identify horses that presumably have been castrated but have viable testicular tissue.
SUMMARY
A cannulation technique was developed to collect blood samples from the ovarian vein of mares over an extended period. Ovarian venous cannulae placed in 4 mares remained patent for a mean (± sem) duration of 36.8 (± 6.2) days. During mid-diestrus, concentrations of progesterone in the ovarian vein ipsilateral to the corpus luteum (1,663.8 ± 238.8 ng/ml) were significantly (P < 0.001) higher than concentrations measured in paired samples from the jugular vein (6.1 ± 0.3 ng/ml). Concentration of estradiol in the ovarian vein ranged from a mean of 1,053.2 ± 303.1 pg/ml during diestrus to 3,353.8 ± 1,052.8 pg/ml during estrus, whereas values for 74% of samples collected concurrently from the jugular vein were near or below the sensitivity of the assay (10 pg/ml).
Results of the study indicate that patent long-term ovarian vein cannulation can be achieved in mares. The cannulation technique provides access to important fundamental information on equine reproductive endocrinology, which to our knowledge, has not been available.
Abstract
Objective—To determine the adsorptive capability of di-tri-octahedral smectite (DTOS) on Clostridium perfringens alpha, beta, and beta-2 exotoxins and equine colostral antibodies.
Sample Population—3 C perfringens exotoxins and 9 colostral samples.
Procedures—Alpha, beta, and beta-2 exotoxins were individually co-incubated with serial dilutions of DTOS or bismuth subsalicylate, and the amount of toxin remaining after incubation was determined via toxin-specific ELISAs. Colostral samples from healthy mares were individually co-incubated with serial dilutions of DTOS, and colostral IgG concentrations were determined via single radial immunodiffusion assay.
Results—Di-tri-octahedral smectite decreased the amount of each C perfringens exotoxin in co-incubated samples in a dose-dependent manner and was more effective than bismuth subsalicylate at reducing exotoxins in vitro. Decreases in the concentration of IgG were detected in samples of colostrum that were combined with DTOS at 1:4 through 1:16 dilutions, whereas no significant decrease was evident with DTOS at the 1:32 dilution.
Conclusions and Clinical Relevance—Di-tri-octahedral smectite effectively adsorbed C perfringens exotoxins in vitro and had a dose-dependent effect on the availability of equine colostral antibodies. Results suggested that DTOS may be an appropriate adjunctive treatment in the management of neonatal clostridiosis in horses. In vivo studies are necessary to fully assess the clinical efficacy of DTOS treatment.
Abstract
Objective—To determine the incidence, ultrasonographic characteristics, and risk factors associated with embryonic development characterized by formation of an embryonic vesicle without an embryo in mares.
Design—Prevalence survey.
Animals—159 pregnant mares.
Procedure—From 1994 to 1998, mares between 11 and 40 days after ovulation with normal and abnormal embryonic development were examined ultrasonographically, and characteristics of each conceptus were recorded.
Results—The incidence of abnormal embryonic development in mares characterized by formation of an embryonic vesicle without an embryo was 7/159 (4.4%) during the 5 breeding seasons. Age and breed of mare or type of semen used did not differ for mares with normal and abnormal embryonic development. The percentage of mares in which the conceptus was undersized during ≥ 1 examination was significantly higher for mares with abnormal conceptuses (5/7), compared with mares with normal conceptuses (2/147; 1.4%). The percentage of examinations during which the conceptus was undersized was significantly higher for abnormal conceptuses (12/27; 44.4%), compared with normal conceptuses (4/448; 0.9%).
Conclusion and Clinical Relevance—To diagnose an embryonic vesicle without an embryo, mares should be examined by use of transrectal ultrasonography on day 25 after ovulation. When an embryo cannot be identified at that time, mares should be reexamined at intervals of 1 to 3 days until day 30. Because undersized conceptuses are more likely to be abnormal, development of undersized conceptuses should be monitored closely. (J Am Vet Med Assoc 2000;217:58–63)
Abstract
Objective—To develop a broad-range 28S ribosomal DNA quantitative PCR (qPCR) assay for detection of fungal DNA in equine endometrial samples.
Sample—12 fungal samples from a clinical diagnostic laboratory and 29 samples obtained from 17 mares.
Procedures—The qPCR assay was optimized with commercially acquired fungal organisms and validated with samples obtained from the clinical diagnostic laboratory. Subsequently, 29 samples from 17 mares suspected of having fungal endometritis were evaluated via the qPCR assay and via traditional fungal culture and endometrial cytology. Amplicons from the qPCR assay were subjected to genetic sequencing to identify the organisms.
Results—The qPCR assay theoretically had a detection threshold of 2 organisms of Candida albicans. Fungal DNA was amplified from all 12 fungal samples from the commercial diagnostic laboratory. Fungal identification by use of genetic sequencing was successful for 34 of 36 amplicons from the 12 samples assayed. A fungal agent was identified via qPCR assay and genetic sequencing in all 12 samples; in contrast, a fungal agent was identified in only 8 of 12 samples via standard fungal culture and biochemical analysis. The qPCR assay detected fungal DNA in samples from 12 of 17 mares suspected of having fungal endometritis.
Conclusions and Clinical Relevance—A rapid, sensitive, and repeatable qPCR assay was developed for detection of fungal DNA from equine endometrial samples. The qPCR may prove to be clinically useful as an adjunct to microbial culture and cytologic examination to provide identification of fungal organisms in a timely manner.
