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in Journal of the American Veterinary Medical Association

Summary

Questionnaires regarding the use of prostaglandin F and its analogues (hereafter referred to as pg) were sent to 332 Alabama beef cattle owners and to 279 Alabama dairy cattle owners after attempting to contact them by telephone to request their participation in the survey. Questionnaires concerning the use of pg in their clients’ herds were likewise sent to 147 food animal and mixed animal practitioners in Alabama after attempting telephone contact. Response among beef cattle owners, dairy cattle owners, and veterinarians to whom questionnaires were mailed was 64.5, 61.6, and 75.5%, respectively.

Only 7.4% (13 of 175) of respondent beef cattle owners reported use of pg in their herds, and this use was predominantly for artificial insemination and embryo transfer. In contrast, 66.5% (109 of 164) of respondent dairy cattle owners reported use of pg, generally with satisfactory results, for some of the following conditions: unobserved estrus (n = 77), uterine infections (n = 74), retained placenta (n = 65), cystic ovaries (n = 56), estrus synchronization (n = 45), and induction of parturition (n = 13).

Although 94.9% of respondent veterinarians treated cattle with pg, those attending beef herds thought that more important strategies were available for improvement of beef cattle productivity than increased use of pg. Among these strategies were shorter calving seasons, improved nutrition, better record keeping, more frequent herd health visits, improved animal identification, and increased use of bull breeding soundness examinations. Likewise, dairy practitioners thought that improved estrus detection, more frequent herd health visits, improved nutrition, better artificial insemination technique, and improved record keeping were more important for improved production than was increased use of pg.

Free access
in Journal of the American Veterinary Medical Association

Summary

The F waves evoked by supramaximal stimulation of distal tibial nerve were evaluated in chickens aged 2 to 15 weeks. Latency of these potentials increased from mean ± sd 11.4 ± 0.12 ms at week 2 to mean 12.88 ± 0.65 ms at week 15. The F-wave latency increased linearly with age. When this latency was corrected for a standard distance to compensate for the increasing limb length with age, latency decreased with maturity.

Free access
in American Journal of Veterinary Research

Summary

Compound motor-nerve action potentials evoked by supramaximal stimulation of the proximal and distal aspects of the tibial nerve were evaluated in chickens 1 to 15 weeks old. Motor-nerve conduction velocity increased from a mean of 22.6 m/s at week 1 to a mean of 52.7 m/s at week 15. The increase in conduction velocity was greatest for the first few weeks, and reached a plateau at 10 weeks Subcutaneous limb temperature, limb length, and proximal latency measurements also increased with age; however, distal latency measurements were not significantly influenced by age. A quadratic equation was calculated to predict mean motor-nerve conduction velocity for maturing chickens.

Free access
in American Journal of Veterinary Research

SUMMARY

Newborn foals of mares grazing on Acremonium coenophialum-infected fescue pasture throughout gestation or from gestation day 300 to parturition had increased gestation duration and decreased serum triiodothyronine concentration. Pregnant mares were allotted to 4 treatments: grazing continuously on endophyte-free (E) fescue, grazing continuously on endophyte-infected (E+) fescue, grazing on E+ fescue from gestation day 300 to parturition, and grazing on E+ fescue from conception to gestation day 300. Morphometric studies indicated that foals born to mares exposed to endophyte late in gestation had large, distended thyroid follicles lined by flat cuboidal epithelial cells. Mean triiodothyronine concentration in foals exposed to endophyte (395.2 ng/dl) was decreased (P < 0.01), compared with mean values in control foals (778.0 ng/dl). Thyroxine and reverse triiodothyronine concentrations were not significantly different among groups. Foal organ weight as a percentage of foal body weight was not significantly different among experimental groups.

Free access
in American Journal of Veterinary Research

Abstract

Case Description—A 2.5-year-old spayed female Persian cat was evaluated for acute inability to close its mouth.

Clinical Findings—A wry-mouth malocclusion was evident, and the right side of the mandible was longer than the left side. The right mandibular tooth row appeared to be lowered. The lower jaw was persistently maintained in an open position. The presumptive diagnosis was open-mouth jaw locking. Diagnostic imaging with computed tomography and 3-dimensional reconstruction was performed for definitive diagnosis and to achieve a better understanding of the lesions. Imaging revealed locking of the right ramus of the mandible, which was displaced ventrolaterally, causing the coronoid process to impinge on the right zygomatic arch.

Treatment and Outcome—A bilateral partial ostectomy of the rostroventral margins of the zygomatic arches with an autogenous fat graft implantation was performed. The cat recovered without complications and by the following morning was bright, alert, and responsive and eating canned cat food comfortably. One year after surgery, the owner reported that the cat had continued to function well, was eating normally, and had not had any observed locking episodes since surgery.

Clinical Relevance—Unlike radiographic imaging, computed tomography may be used to create 3-dimensional reconstructions of structures in cases of suspected open-mouth jaw locking; improve evaluation of the lesions; and improve decision-making and client education for diagnosis, treatment options, and prognosis.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare ocular structures of Quarter Horses homozygous for hereditary equine regional dermal asthenia (HERDA) with those of Quarter Horses not affected by HERDA (control horses) and to determine the frequency of new corneal ulcers for horses with and without HERDA during a 4-year period.

Design—Cohort study of ocular structures and retrospective case series of horses with and without HERDA.

Animals—The cohort portion of the study involved 10 Quarter Horses with HERDA and 10 Quarter Horses without HERDA; the retrospective case series involved 28 horses with HERDA and 291 horses without HERDA.

Procedures—Ophthalmic examinations, Schirmer tear tests, tonometry, corneal pachymetry, histologic examinations, and scanning electron microscopy (SEM) were performed in cohorts of Quarter Horses with and without HERDA. Records were reviewed to determine the incidence of corneal ulcers in horses with and without HERDA during a 4-year period.

Results—Corneal thickness of horses with HERDA was significantly less than that of control horses, but tear production of horses with HERDA was significantly greater than that of control horses. Results of SEM revealed zones of disorganized, haphazardly arranged collagen fibrils in corneas of horses with HERDA that were not evident in corneas of control horses. The incidence of corneal ulcers was significantly greater for horses with HERDA than for horses without HERDA during the 4-year period.

Conclusions and Clinical Relevance—Alterations in corneal thickness, arrangement of collagen fibers, and incidence of corneal ulcers indicated that abnormalities in horses with HERDA were not limited to the skin.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether thalidomide inhibits the growth of primary and pulmonary metastatic canine osteosarcoma in mice after xenotransplantation.

Animals—Athymic nude mice.

Procedure—Canine osteosarcoma cells were injected SC in 50 mice. Mice were randomly placed into the following groups: control group (n = 13; DMSO [drug vehicle] alone [0.1 mL/d, IP]); low-dose group (12; thalidomide [100 mg/kg, IP]), mid-dose group (13; thalidomide [200 mg/kg, IP]); and high-dose group (12; thalidomide [400 mg/kg, IP]). Starting on day 8, treatments were administered daily and tumor measurements were performed for 20 days. On day 28, mice were euthanatized and primary tumors were weighed. Lungs were examined histologically to determine the number of mice with metastasis and tumor emboli. Mean area of the pulmonary micrometastatic foci was determined for mice from each group.

Results—Primary tumor size and weight were not significantly different among groups. The number of mice in the mid-dose (200 mg/kg) and high-dose (400 mg/kg) groups with micrometastasis was significantly less than the number of control group mice; however, the number of mice with tumor emboli was not affected by thalidomide treatment. Size of micrometastasis lesions was not affected by thalidomide treatment.

Conclusions and Clinical Relevance—Mean area of micrometastases was not affected by treatment; however, growth of micrometastases had not yet reached an angiogenesis-dependent size. Although thalidomide did not affect growth of primary tumors in mice after xenotransplantation of canine osteosarcoma cells, our findings indicate that thalidomide may interfere with the ability of embolic tumor cells to complete the metastatic process within the lungs. ( Am J Vet Res 2004;65:659–664)

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To determine whether infrared thermographic images obtained the morning after overnight heat abatement could be used as the basis for diagnostic algorithms to predict subsequent heat stress events in feedlot cattle exposed to high ambient temperatures.

ANIMALS 60 crossbred beef heifers (mean ± SD body weight, 385.8 ± 20.3 kg).

PROCEDURES Calves were housed in groups of 20 in 3 pens without any shade. During the 6 am and 3 pm hours on each of 10 days during a 14-day period when the daily ambient temperature was forecasted to be > 29.4°C, an investigator walked outside each pen and obtained profile digital thermal images of and assigned panting scores to calves near the periphery of the pen. Relationships between infrared thermographic data and panting scores were evaluated with artificial learning models.

RESULTS Afternoon panting score was positively associated with morning but not afternoon thermographic data (body surface temperature). Evaluation of multiple artificial learning models indicated that morning body surface temperature was not an accurate predictor of an afternoon heat stress event, and thermographic data were of little predictive benefit, compared with morning and forecasted weather conditions.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated infrared thermography was an objective method to monitor beef calves for heat stress in research settings. However, thermographic data obtained in the morning did not accurately predict which calves would develop heat stress later in the day. The use of infrared thermography as a diagnostic tool for monitoring heat stress in feedlot cattle requires further investigation.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine pharmacokinetics and tissue concentrations of azithromycin in ball pythons ( Python regius ) after IV or oral administration of a single dose.

Animals—2 male and 5 female ball pythons.

Procedures—Using a crossover design, each snake was given a single dose of azithromycin (10 mg/kg) IV. After a 4-week washout period, each snake was given a single dose of azithromycin (10 mg/kg) orally. Blood samples were collected prior to dose administration and 1, 3, 6, 12, 24, 48, 72, and 96 hours after azithromycin administration. Azithromycin was quantitated by use of liquid chromatography-mass spectrometry.

Results—After IV administration, azithromycin had an apparent volume of distribution of 5.69 L/kg and a plasma clearance of 0.19 L/h/kg. Harmonic means for the terminal half-life were 17 hours following IV administration and 51 hours following oral administration. Mean residence times were 37 and 94 hours following IV and oral administration, respectively. Following oral administration, azithromycin had a peak plasma concentration (Cmax) of 1.04 µg/mL, a time to Cmax of 8.4 hours, and a prolonged mean absorption time of 57 hours. Mean oral bioavailability was 77%. Tissue concentrations ranged from 4 to 140 times the corresponding plasma concentration at 24 and 72 hours after azithromycin administration.

Conclusions and Clinical Relevance—Azithromycin is well absorbed and tolerated by ball pythons. On the basis of plasma pharmacokinetics and tissue concentration data, we suggest an azithromycin dosage in ball pythons of 10 mg/kg, orally, every 2 to 7 days, depending upon the site of infection and susceptibil ity of the infective organism. (Am J Vet Res 2003;64:225–228)

Full access
in American Journal of Veterinary Research