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Summary

The effect of metoclopramide (mc), a dopamine antagonist on luteinizing hormone (lh), was examined in anestrous primaparous cows. Metoclopramide has been found to be beneficial in overcoming fescue toxicosis; increasing lh secretion stimulates return to ovulatory function after parturition. Consequently, if mc had negative effect on lh secretion, it would indicate that administration of mc to reproducing animals might be limited. Of 14 postpartum (47 to 66 days) cows, 7 were given mc (4 mg/kg of body weight, iv), and 7 served as controls. Blood was obtained via jugular cannulas at 15-minute intervals for 8 hours; mc was given at the end of the first hour, and gonadotropin-releasing hormone (GnRH, 7 mg/kg), was given iv at the end of hour 7 as a challenge stimulus for lh secretion. Prior to GnRH administration, mc did not have significant effect on lh secretion, as judged by mean serum lh concentration, lh pulse frequency, and lh pulse amplitude. Administration of mc resulted in greater (P < 0.05) lh response to GnRH, indicating enhanced secretory ability when the pituitary gland was challenged. Serum prolactin concentration was increased (P < 0.01) by mc administration. Therefore, mc did not have adverse effect on lh secretion in postpartum cows.

Free access
in American Journal of Veterinary Research

SUMMARY

The efficacy, safety, and compatibility of fenbendazole (fbz) and clorsulon (cln) were tested after oral administration of label recommended and of higher (5 ×) dosage rates to calves naturally infected with gastrointestinal nematodes and Fasciola hepatica. Results for 42 calves allotted to 4 treatment groups indicated a similar efficacy against mature F hepatica by fbz (5 mg/kg of body weight) and cln (7 mg/kg) in a combined oral suspension, compared with cln (7 mg/kg) alone (100 vs 99% reduction). A lesser efficacy was observed against immature flukes (88.6 and 84.9% reduction, respectively). Calves given 25 mg of fbz/kg and 35 mg of cln/kg had nearly complete reduction of both mature (99.6%) and immature flukes (99.1%). Fasciola egg counts were reduced by > 99.5% in all treated groups. Against Ostertagia ostertagi, the percentage ofe fficacy of the combined fbz (5 mg/kg) and cln (7 mg/kg) treatment was 94.3% against adults and 81.3% against inhibited larvae. Efficacy against all other nematodes was 100%, except against Cooperia spp adults (98.3%) and immature Oesaphagostomum radiatum (88.0%). At 5 × dosage rates for fbz and cln, percentage of removal of adults and inhibited larvae of O ostertagi was 99.3 and 99.0%, respectively, and 99 to 100% for other nematodes. Results indicate that fbz and cln are compatible when mixed together and administered as an oral suspension to cattle and that the efficacy is similar to that of the drugs individually. On the basis of further results, we suggest that summer treatment may be superior in preventive value for gastrointestinal nematodes and F hepatica, compared with spring treatment, because of seasonal infection dynamics of the major cattle parasites in Louisiana.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To test the effects of computed tomography (CT) image plane and window settings on diagnostic certainty for CT characteristics associated with dysplastic elbow joints (elbow joint dysplasia) in dogs and to provide optimal display guidelines for these CT characteristics.

Sample Population—CT images of 50 dysplastic elbow joints from 49 lame dogs and 10 elbow joints from 5 sound dogs.

Procedures—CT image data were obtained in transverse, sagittal, and dorsal planes. Each plane was examined by use of 3 Hounsfield unit (HU) window settings. Two veterinary radiologists independently evaluated sets of CT images for evidence of 7 CT characteristics. Effect of elbow joint status, image plane, and window settings on diagnostic certainty for these CT characteristics was tested by use of a visual analogue scale.

Results—Diagnostic certainty for abnormalities of the medial coronoid process (MCP) and radial incisure was highest in the transverse plane, subchondral defects or sclerosis of the trochlea humeri was highest in the dorsal plane, and joint incongruity was highest in the sagittal plane. Certainty for hypoattenuating subchondral defects or fissures was highest at 2,500 or 3,500 HUs, whereas certainty for subchondral sclerosis was highest at 1,500 HUs and lowest at 3,500 HUs.

Conclusions and Clinical Relevance—Diagnostic certainty for CT characteristics of elbow joint dysplasia in dogs was affected by image display variables. Diagnostic certainty for altered subchondral bone density was primarily influenced by window settings, whereas structural MCP abnormalities and joint incongruity were influenced most by image plane.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine concentrations of marbofloxacin in alveolar macrophages (AMs) and epithelial lining fluid (ELF) and compare those concentrations with plasma concentrations in healthy dogs.

Animals—12 adult mixed-breed and purebred hounds.

Procedure—10 dogs received orally administered marbofloxacin at a dosage of 2.75 mg/kg every 24 hours for 5 days. Two dogs served as nontreated controls. Fiberoptic bronchoscopy and bronchoalveolar lavage procedures were performed while dogs were anesthetized with propofol, approximately 6 hours after the fifth dose. The concentrations of marbofloxacin in plasma and bronchoalveolar fluid (cell and supernatant fractions) were determined by use of high-performance liquid chromatography with detection of fluorescence.

Results—Mean ± SD plasma marbofloxacin concentrations 2 and 6 hours after the fifth dose were 2.36 ± 0.52 µg/mL and 1.81 ± 0.21 µg/mL, respectively. Mean ± SD marbofloxacin concentration 6 hours after the fifth dose in AMs (37.43 ± 24.61 µg/mL) was significantly greater than that in plasma (1.81 ± 0.21 µg/mL) and ELF (0.82 ± 0.34 µg/mL), resulting in a mean AM concentration-to-plasma concentration ratio of 20.4, a mean AM:ELF ratio of 60.8, and a mean ELF-to-plasma ratio of 0.46. Marbofloxacin was not detected in any samples from control dogs.

Conclusions and Clinical Relevance—Marbofloxacin concentrations in AMs were greater than the mean inhibitory concentrations of major bacterial pathogens in dogs. Results indicated that marbofloxacin accumulates in AMs at concentrations exceeding those reached in plasma and ELF. The accumulation of marbofloxacin in AMs may facilitate treatment for susceptible intracellular pathogens or infections associated with pulmonary macrophage infiltration. (Am J Vet Res 2005;66:1770–1774)

Full access
in American Journal of Veterinary Research

Summary

Electrodes were surgically implanted at 15-cm intervals in the jejunum and ileum of 4 healthy neonatal calves so that myoelectric activity could be recorded on 2 consecutive days. On the first day, each calf received a control treatment, and myoelectric activity was recorded for 340 minutes. Phase I was recorded for a mean of 175.8 ± 22.8 minutes (51.5%), phase II for 124 ± 27.4 minutes (36.5%), and phase III for 40.3 ± 6 minutes (11.9%). On the second day, each calf was treated with approximately 200 μg of heat-stable enterotoxin (STa) of Escherichia coli orally. All calves developed diarrhea after the administration of STa. Phase I was recorded for a mean of 92.5 ± 42.3 minutes (27.2%), phase II for 227.3 ± 52.5 minutes (66.9%), and phase III for 20.3 ± 11.4 minutes (6.0%). Increase in phase II and decrease in phases I and III after STa administration were significant (P < 0.05). Duration of the migrating myoelectric complex was longer after STa administration (median, 64 minutes), compared with the control treatment (median, 54 minutes). Minute rhythms, recorded on the day of toxin administration, ranged from 49 to 153 minutes. There was no difference between the number of migrating action potential complexes on the control days (range, 1 to 10), compared with those on treatment days (range, 1 to 14).

These findings are suggestive that enterotoxin-induced diarrhea of calves is accompanied by increased total spiking activity and minute rhythms in the distal portion of the jejunum and ileum.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine the modes of transmission of Aleutian mink disease in a natural outbreak.

Animals

5,580 black and 9,087 brown mink from a ranch with an outbreak of Aleutian mink disease.

Procedure

Each mink had serum tested by counter-electrophoresis for Aleutian disease antibody. If a mink was seropositive for Aleutian disease virus by counter-electrophoresis, it was considered to be infected. Correlation of prevalence of the disease in kits and parents was determined. Spatial arrangement of infected and uninfected mink also was studied.

Results

Infected black dams were more likely to produce infected kits than were uninfected dams. In contrast, infected black sires were less likely to produce infected kits than were uninfected sires. In brown mink, in which prevalence of Aleutian disease was lower, transmission from infected dams and sires to kits was apparent. Infected black mink appeared to be more efficient in transmitting the disease horizontally than were infected brown mink. Although the spatial arrangement of infected mink indicated that mechanical transmission of the disease may be the most efficient mode of horizontal transmission, airborne transmission also occurred.

Conclusions and Clinical Relevance

Infected sires with nonprogressive Aleutian disease may confer protection to their kits in the face of a severe outbreak. Brown mink may be less able to transmit the virus horizontally than are black mink. Airborne transmission is substantial, but may not be as efficient as mechanical transmission. (Am J Vet Res 1996;57:1706–1710)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To assess the suitability of lithium dilution as a method for measuring cardiac output in anesthetized horses, compared with thermodilution and transesophageal Doppler echocardiography.

Animals—6 horses (3 Thoroughbreds, 3 crossbreeds).

Procedure—Cardiac output was measured in 6 anesthetized horses as lithium dilution cardiac output (LiDCO), thermodilution cardiac output (TDCO), and transesophageal Doppler echocardiographic cardiac output (DopplerCO). For the LiDCO measurements, lithium chloride was administered IV, and cardiac output was derived from the arterial lithium dilution curve. Sodium nitroprusside, phenylephrine hydrochloride, and dobutamine hydrochloride were used to alter cardiac output. Experiments were divided into 4 periods. During each period, 3 LiDCO measurements, 3 DopplerCO measurements, and 3 sets of 3 TDCO measurements were obtained.

Results—70 comparisons were made between LiDCO, DopplerCO, and triplicate TDCO measurements over a range of 10 to 43 L/min. The mean (± SD) of the differences of LiDCO – TDCO was –0.86 ± 2.80 L/min; LiDCO = –1.90 + 1.05 TDCO (r = 0.94). The mean of the differences of DopplerCO – TDCO was 1.82 ± 2.67 L/min; DopplerCO = 2.36 + 0.98 TDCO (r = 0.94). The mean of the differences of LiDCO – DopplerCO was –2.68 ± 3.01 L/min; LiDCO = –2.53 + 0.99 DopplerCO (r = 0.93).

Conclusions and Clinical Relevance—These results indicate that lithium dilution is a suitable method for measuring cardiac output in horses. As well as being accurate, it avoids the need for pulmonary artery catheterization and is quick and safe to use. Monitoring cardiac output during anesthesia in horses may help reduce the high anesthetic mortality in this species. (Am J Vet Res 2000;61:731–737)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether administration of 2 doses of a multivalent, modified-live virus vaccine prior to breeding of heifers would provide protection against abortion and fetal infection following exposure of pregnant heifers to cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV) and cattle with acute bovine herpesvirus 1 (BHV1) infection.

Design—Randomized controlled clinical trial.

Animals—33 crossbred beef heifers, 3 steers, 6 bulls, and 25 calves.

Procedures—20 of 22 vaccinated and 10 of 11 unvaccinated heifers became pregnant and were commingled with 3 steers PI with BVDV type 1a, 1b, or 2 for 56 days beginning 102 days after the second vaccination (administered 30 days after the first vaccination). Eighty days following removal of BVDV-PI steers, heifers were commingled with 3 bulls with acute BHV1 infection for 14 days.

Results—After BVDV exposure, 1 fetus (not evaluated) was aborted by a vaccinated heifer; BVDV was detected in 0 of 19 calves from vaccinated heifers and in all 4 fetuses (aborted after BHV1 exposure) and 6 calves from unvaccinated heifers. Bovine herpesvirus 1 was not detected in any fetus or calf and associated fetal membranes in either treatment group. Vaccinated heifers had longer gestation periods and calves with greater birth weights, weaning weights, average daily gains, and market value at weaning, compared with those for calves born to unvaccinated heifers.

Conclusions and Clinical Relevance—Prebreeding administration of a modified-live virus vaccine to heifers resulted in fewer abortions and BVDV-PI offspring and improved growth and increased market value of weaned calves.

Full access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To establish a pathoepidemiological model to evaluate the role of SARS-CoV-2 infection in the first 10 companion animals that died while infected with SARS-CoV-2 in the US.

ANIMALS

10 cats and dogs that tested positive for SARS-CoV-2 and died or were euthanized in the US between March 2020 and January 2021.

PROCEDURES

A standardized algorithm was developed to direct case investigations, determine the necessity of certain diagnostic procedures, and evaluate the role, if any, that SARS-CoV-2 infection played in the animals’ course of disease and death. Using clinical and diagnostic information collected by state animal health officials, state public health veterinarians, and other state and local partners, this algorithm was applied to each animal case.

RESULTS

SARS-CoV-2 was an incidental finding in 8 animals, was suspected to have contributed to the severity of clinical signs leading to euthanasia in 1 dog, and was the primary reason for death for 1 cat.

CONCLUSIONS AND CLINICAL RELEVANCE

This report provides the global community with a standardized process for directing case investigations, determining the necessity of certain diagnostic procedures, and determining the clinical significance of SARS-CoV-2 infections in animals with fatal outcomes and provides evidence that SARS-CoV-2 can, in rare circumstances, cause or contribute to death in pets.

Free access
in Journal of the American Veterinary Medical Association