bluuebunny/crossref_metadata_2025 huggingface dataset:
Tumor necrosis factor-α Production in swine after oral or respiratory challenge exposure with live Salmonella typhimurium or Salmonella choleraesuis
Authors: Stabel Thomas J. , Fedorka-Cray Paula J. , Gray Jeffrey T.
Published: January 2024

A series of experiments was conducted to document tumor necrosis factor-α (tnf) activity in serum of swine after inoculation with Salmonella spp endotoxin and after oral or respiratory tract challenge exposure with live Salmonella spp. For experiment 1, a potentially lethal dose of S typhimurium endotoxin (25 μg/kg of body weight) was administered iv, and serum tnf activity was measured. High tnf (approx 700 IU/ml) activity at 1 to 2 hours after administration of the inoculum was associated with death, whereas lower tnf (approx 30 IU/ml) activity was associated with a general prolonged state of shock. For experiment 2, pigs were administered a nonlethal dose (5 μg/kg, iv) of either S typhimurium or S choleraesuis endotoxin. Difference in the ability to induce porcine serum tnf activity was not observed between strains. During experiment 3, pigs were inoculated with 104 colony-forming units of S typhimurium χ4232 either orally by gelatin capsule (gc) or by intranasal (in) instillation. A late serum tnf response (17 IU/ml) was measured at 6 weeks after in inoculation. A serum tnf response was not detected in gc-inoculated pigs. All tissues and feces were test-negative for S typhimurium prior to the 6-week tnf response. Serum tnf activity may be related to clearance of S typhimurium after respiratory tract exposure, but it is not important to or indicative of clearance of orally presented S typhimurium in swine. During experiment 4, pigs were inoculated with 106 colony-forming units of S typhimuriumχ4232 similarly as for experiment 3. Challenge exposure with this medium-size dose of inoculum induced a prolonged peak serum tnf response (37 IU/ml) between 2 and 4 weeks after in inoculation. Again, serum tnf activity was not detected in gc-inoculated pigs. Data suggest that clearance of a medium-size dose (106) of inoculum may be influenced by the prolonged higher serum tnf activity. For experiments 5 and 6, pigs were inoculated in with 103, 106, 108, or 109 S choleraesuis χ3246. A measurable, yet statistically nonsignificant, serum tnf response was observed for all doses. Pigs inoculated by gc with 108 S choleraesuis χ3246 had similar results. High doses (> 106) of live S choleraesuis were associated with clinical signs of endotoxic shock. Clearance of S choleraesuis, or lack thereof, did not correlate with serum tnf activity.
Efficacy of a variety of disinfectants against Actinobacillus pleuropneumoniae serotype 1
Authors: Gutiérrez César B. , Barbosa José I. Rodríguez , Suárez Juan , González Óscar R. , Tascón Rubén I. , Ferri Elías F. Rodríguez
Published: January 2024

The efficacy of 23 disinfectants (including the most commonly used chemical groups) and 6 quaternary ammonium compound based commercial formulations against Actinobacillus pleuropneumoniae serotype 1 (ATCC 4074) was studied. The organisms were tested in suspension and carrier tests with serum as the organic matter. Chloramine-T, hydrogen peroxide, glutaraldehyde, and mercurochrome alone, and a quaternary ammonium compound formulation containing 10% benzalkonium chloride, 2.5% glutaraldehyde, 6.8% glyoxal, and 6% formaldehyde were effective in all tests, regardless of the presence or absence of organic load. All but 2 of the nonformulated disinfectants (sodium hypochlorite and an iodophor) caused at least a 3-log10 reduction in colony-forming units in the suspension test. However, most of the disinfectants were not as effective in the carrier test as in the suspension test; this difference ranged from a 1- to 5-log10 reduction in colony-forming units. In addition, the presence of serum considerably reduced the disinfectant capacities of most of the compounds tested, particularly in the carrier test. These results indicate the importance of selecting suitable disinfectants for routine use on surfaces contaminated with this organism, especially in the presence of organic matter. Chloramine-T and the aforementioned commercial formulation were also tested directly under field conditions in pig nurseries, confirming their high effectiveness.
Enzymatic analysis of liver samples from rainbow trout for diagnosis of blue-green algae-induced toxicosis
Authors: Sahin Ali , Tencalla Francesca G. , Dietrich Daniel R. , Mez Konstanze , Naegeli Hanspeter
Published: January 2024

Microcystin and related toxic peptides produced by cyanobacteria (blue-green algae) are potent and selective inhibitors of protein phosphatases 1 and 2A. We adapted existing enzymatic techniques to analyze the liver of rainbow trout after oral administration of hepatotoxic cyanobacteria. Liver tissue was removed 3 and 12 hours after treatment, and phosphatase activity was determined in liver extracts, using a specific phosphoprotein substrate. In all samples from fish exposed to toxic cyanobacteria, phosphatase activity was suppressed, whereas the control enzyme, lactate dehydrogenase, present in the same liver extract, was not affected by cyanobacteria. Thus, experimental poisoning by hepatotoxic cyanobacteria resulted in an abnormally low ratio of phosphatase to lactate dehydrogenase activity in the liver extracts. These results indicate that specific inhibition of phosphatases 1 and 2A may provide a useful diagnostic tool to determine the early effects of cyanobacteria toxic peptides directly in liver samples from poisoned animals. Although this test was developed with rainbow trout, it should be possible to extend the analysis of liver phosphatase activity to other species, including sheep and cattle, which are frequently affected by hepatotoxic cyanobacteria.
Heritability of the depth of the opening of the ciliary cleft in Samoyeds
Authors: Ekesten Björn , Torrång Ingrid
Published: January 2024

Ocular examination, including gonioscopy and ultrasonographic biometry (biological measurement), was performed in healthy, purebred Samoyeds. When the dogs were subclassified according to the degree of kinship with cases of primary angle-closure glaucoma, it was found that the opening of the ciliary cleft was wider in dogs less related to dogs with primary angle-closure glaucoma than in more closely related dogs. Furthermore, multivariate analysis of the material indicated that parentage of a dog has a substantial effect on the intraocular distances studied in this investigation (relative depth of the opening of the ciliary cleft, relative corneal thickness, relative anterior chamber depth, relative lens thickness, and relative length of the vitreous body). Finally, heritability of the relative depth of the opening of the ciliary cleft was estimated at 56% and that of the common environmental factor at 19%. The results are indicative of a hereditary component in primary angle-closure glaucoma in the Samoyed breed.
Pharmacokinetics of enrofloxacin in clinically normal dogs and mice and drug pharmacodynamics in neutropenic mice with Escherichia coli and staphylococcal infections
Authors: Meinen Jeffrey B. , McClure J. T. , Rosin Eberhard
Published: January 2024

Pharmacodynamic variables of enrofloxacin were investigated in a neutropenic mouse Escherichia coli and staphylococcal thigh infection model. Enrofloxacin pharmacokinetics in clinically normal mice and dogs were compared to confirm that doses evaluated in the mouse model would include enrofloxacin doses appropriate for use in dogs. Mice were made neutropenic by treatment with cyclophosphamide and injected in the thigh muscle with approximately 106 colony-forming units of E coli (n = 2) or a staphylococcal (n = 2) clinical isolate. Enrofloxacin dosages tested ranged from 0.78 to 50 mg/kg of body weight and 6.25 to 200 mg/kg in the E coli and staphylococcal infection trials, respectively. In each 24-hour dosage trial, enrofloxacin was administered SC as a single dose or in divided doses given every 3, 6, or 12 hours. Comparison of log10 colonyforming units per thigh muscle in untreated control mice and mice treated with enrofloxacin was used as a measure of efficacy. Two-way anova was used to determine that the enrofloxacin total dose, but not the dose frequency, was significant in determining drug efficacy. Pharmacokinetic values analyzed by use of multivariant stepwise linear regression analysis indicated that the area under the concentration-time curve, but not time above minimum inhibitory concentration, was significant in predicting efficacy of enrofloxacin treatment. We conclude that enrofloxacin killing of E coli and staphylococci is concentration dependent and not time dependent.
Comparison of the effects of low-molecular-weight and unfractioned heparin in horses
Authors: Monreal Luis , Villatoro Antonio J. , Monreal Manuel , Espada Yvonne , Anglés Anna M. , Ruiz-Gopegui Rafael
Published: January 2024

Thirty healthy male horses were allotted to 3 groups and treated blindly during 4 days. Group-1 horses received unfractioned calcium heparin (100 IU/kg of body weight, sc, q 12 h). Group-2 horses received a single dose of a low-molecular-weight heparin (50 anti-Xa IU/kg, sc) every morning, and a similar volume of saline solution every evening. Group-3 horses received the vehicle (saline solution), sc, every 12 hours. Citrated and edta-anticoagulated blood samples were collected before starting the medication (T-0) and once daily 3 hours after each morning injection (T-3, T-27, T-51, and T-75). The pcv, hemoglobin concentration, rbc and platelet counts, and clotting times (activated partial thromboplastin time and thrombin time) were determined, and a microscopic examination to detect hemagglutination was performed. Plasma concentration of heparin was measured by use of the antifactor Xa activity assay. Bleeding time was determined on the first and fourth days, using a double-template method.

The horses given unfractioned heparin had marked agglutination of erythrocytes after the first injection that became more pronounced as treatment progressed. Also, significant decrease in pcv, hemoglobin concentration, and rbc count was observed during treatment. Platelet count was significantly decreased after the first day, and clotting times were significantly prolonged. In contrast to the horses given unfractioned heparin, those given low-molecular-weight heparin did not have any agglutination of erythrocytes during the 4 days of treatment, and there were no significant changes in pcv, hemoglobin concentration, or rbc and platelet counts. Activated partial thromboplastin time increased slightly in the horses given low-molecular-weight heparin, although the values remained within reference range. Both groups of horses achieved adequate concentrations of heparin in plasma for prophylactic purposes, but those given low-molecular-weight heparin achieved those values after the first injection. Bleeding times were not significantly different between heparin-treated horses and horses given saline solution during treatment.

We conclude that low-molecular-weight heparin may be used more safely and conveniently in horses, because it does not affect equine erythrocytes, platelets, or clotting and bleeding times.
Demonstration of tank effect on growth indices of juvenile rainbow trout (Oncorhynchus mykiss) during an ad libitum feeding trial
Authors: Speare David J. , MacNair Neil , Hammell K. L.
Published: January 2024

Growth indices were examined in 24 identically managed tanks, each containing 120 diploid juvenile rainbow trout (initial mean body weight, 9.3 g), during a 12-week study to examine tank effects associated with tank location in a multi-user research facility. Growth indices included mean body weight, feed intake, feed conversion index, and specific growth rate. The null hypothesis that tank effect had no effect on growth over the 12-week period was rejected (P = 0.038), and mean weight in individual tanks differed by as much as 18.7%. During the study, it was determined that the proximity of tanks to common-use walkways in the facility could affect growth indices. This was indicated by significant differences in the mean fish weights among blocks of tanks served by different header tanks after 4 (P = 0.001) and 8 (P = 0.024) weeks. The block containing tanks of fish with the highest mean weight was nearest to the 2 common-use walkways in the facility. Fish in this block of tanks, compared with those in other blocks, had significantly greater feed intake but no significant differences in conversion efficiency. Compensatory growth, a well known growth attribute in fishes, diminished the difference in mean weight between these blocks of tanks by the end of the study. Comparison of paired tanks within header tank blocks indicated that fish in those located nearest to walkways had higher feeding rates over the 12-week period (P = 0.048), but less efficient feed conversion (P = 0.040) than did fish in matched tanks located farthest from walkways. However, there were no differences in mean weight of fish. Results of this trial document the risks involved in identifying fish in a tank as the experimental unit when treatments are administered to the tank of fish, the latter being the true experimental unit.
Ruminal microbial alterations associated with sulfide generation in steers with dietary sulfate-induced polioencephalomalacia
Authors: Cummings B. A. , Gould D. H. , Caldwell D. R. , Hamar D. W.
Published: January 2024

Holstein steers were fed carbohydrate-rich, short-fiber basal diets with and without added sodium sulfate. Steers fed the high-sulfate diet developed the cns disorder polioencephalomalacia (pem). The onset of signs of pem was associated with increased sulfide concentration in the rumen fluid. Over the course of the disease, anaerobic rumen bacteria were enumerated in roll tubes by use of the Hungate method to determine the effect of dietary sulfate on sulfate-reducing bacterial numbers. Media used included a general type for total counts and sulfate-containing media with and without cysteine to assess sulfate-reducing bacteria. Changes in total and sulfate-reducing bacterial numbers attributable to dietary sulfate content were not observed. The capacity to generate hydrogen sulfide from sulfate in fresh rumen fluid in vitro was substantially increased only after steers had been fed the high-sulfate diet for 10 to 12 days, which coincided with the onset of signs of pem. The low capacity for hydrogen sulfide production of rumen fluid taken at earlier times in the feeding period suggests that rumen microorganisms must adapt to higher dietary sulfate content before they are capable of generating potentially toxic concentrations of sulfide.
Pharmacokinetics of the active metabolite of benazepril, benazeprilat, and inhibition of plasma angiotensin-converting enzyme activity after single and repeated administrations to dogs
Authors: King Jonathan N. , Mauron Catherine , Kaiser Günther
Published: January 2024

Plasma pharmacokinetic variables of benazeprilat, the active metabolite of the angiotensin-converting enzyme (ace) inhibitor benazepril, were evaluated in healthy Beagles. Benazeprilat was administered iv at a dosage of 0.5 mg/kg of body weight (n = 9). The elimination half-life of benazeprilat was 3.5 hours, although an additional terminal phase was observed in some dogs. Vehicle (gelatin capsules) or benazepril at dosages of 0.125, 0.25, 0.5, or 1.0 mg/kg was administered orally as a single administration, then once daily for 15 consecutive days (n = 5 or 6/group). Peak benazeprilat concentrations were rapidly attained by 2 hours. Benazeprilat concentrations accumulated moderately with repeated administration, with a peak concentration that was 23% higher and an area under the concentration-time curve that was 34% higher after the 15th dose of benazepril, compared with values after a single dose. The effective half-life for accumulation for all 4 dosages was 12 hours. Steady-state concentrations at 2 hours after administration were achieved after a median (range) of 1 (1 to 6) dose(s).

Pharmacodynamic variables were assessed by measurement of plasma ace activity after oral administration of benazepril or vehicle. All dosages of benazepril caused profound inhibition of ace, with rapid onset of activity (time to peak effect, 2 hours) and long duration of action (single administration of all 4 doses induced inhibition of ace that was significantly different from the value in the control [vehicle-treated] dogs for all time points between 1 and 30 hours). Maximal inhibition at all time points was induced by the 0.25- mg/kg dosage at a single administration and with the lowest dosage tested (0.125 mg/kg) at steady state. At steady state, the 0.25-mg/kg dosage caused (mean ± sem) 96.9 ± 2.0% inhibition of ace activity at maximal effect and 83.6 ± 4.2% at trough effect (24 hours after dosing), indicating minimal variation in peak/trough effect. Steady-state inhibition of ace activity at both peak and trough drug effect was achieved after 1 to 4 doses. The data indicate that benazepril is a potent and long-acting ace inhibitor in dogs.
Effects of tendon grip technique (frozen versus unfrozen) on in vitro surface strain measurements of the equine deep digital flexor tendon
Authors: Matthews Gloria L. , Keegan Kevin G. , Graham Huber L.
Published: January 2024

Objective

To determine effects of tendon grip technique on in vitro surface strain measurements of equine deep digital flexor tendon (DDFT) when loaded in tension.

Sample Population

12 hind limb DDFT from 8 adult horses (mean age, 9.8 years [range, 4.5 to 17 years]; mean body weight, 472 kg [range, 450 to 509 kg]), with no clinical evidence of hind limb lameness.

Design and Procedure

After calibration, liquid mercury strain gauges were sutured to plantar surfaces of the tendons at distal (position 1), middle (position 2), and proximal (position 3) metatarsal regions. Each tendon was affixed to a materials testing machine (distally by the distal phalanx, and proximally by a metal clamp), and loaded once in tension, at a strain rate of 2.8 to 3.0%/s, to 3% clamp displacement. Liquid nitrogen was used to freeze the proximal ends of 6 tendons before placement in the clamp. Proximal ends of the remaining 6 tendons were left unfrozen. Surface strains were determined with the aid of low-resistance bridge circuits. Data were analyzed at time points corresponding to 1, 2, and 3% clamp displacement.

Results

Mean surface strains of tendons with frozen ends were significantly greater than those for tendons with unfrozen ends, and closer to strain measured by clamp displacement, at 1 and 2% clamp displacement. This difference was present but not significant at 3% clamp displacement. Mean local surface strain was not significantly different between the 3 gauge positions.

Conclusions

Freezing tendon ends is a useful technique to increase measured surface strains in equine DDFT, thereby making them closer to universal strain as measured by clamp displacement, and, thus, more likely to represent true surface strain. (Am J Vet Res 1996;57:111-115)
Demonstration of synergistic effects of sulfonamides and dihydrofolate reductase/thymidylate synthase inhibitors against Neospora caninum tachyzoites in cultured cells, and characterization of mutants resistant to pyrimethamine
Authors: Lindsay David S. , Butler Jamie M. , Rippey Natasha S. , Blagburn Byron L.
Published: January 2024

Objective

To examine the efficacies of combinations of 7 sulfonamides and 5 dihydrofolate reductase/thymidylate synthase (DHFR/TS) inhibitors against tachyzoites of Neospora caninum in cultured cells. Mutant tachyzoites that were resistant to pyrimethamine were produced and examined for resistance to other DHFR/TS inhibitors.

Design and Procedures

After 5 days of treatment, a cell culture flask lesion-based assay was used to determine efficacies of combinations of sulfonamides and DHFR/TS inhibitors against N caninum tachyzoites and to evaluate the sensitivity of pyrimethamine-resistant mutants of N caninum to test agents. Cultured cells that were infected with the appropriate strains of N caninum and treated or not treated (controls) with test agents were examined. Mutations were induced by chemical mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidme or by selection for growth in permissive concentration of pyrimethamine.

Results

Synergism was detected for combinations of pyrimethamine, ormetoprim, trimethoprim, or diaveridine with the sulfonamides. Methotrexate did not have improved efficacy when combined with sulfonamides. Two mutants were produced that were resistant to pyrimethamine. Both mutants were resistant to other DHFR/TS inhibitors. Both mutants remained resistant to pyrimethamine in the absence of continuous exposure to the agent, indicating that the induced resistance was stable. Synergism was detected for combinations of DHFR/TS inhibitors and sulfonamides against these pyrimethamine-resistant mutants.

Conclusions

Combinations of suboptimal concentrations of sulfonamides with suboptimal concentrations of DHFR/TS inhibitors results in improved efficacy of the agents in a cell culture assay. Stable resistance to pyrimethamine can be induced in N caninum tachyzoites by use of chemical mutagenesis or by selection.

Clinical Relevance

In vitro evidence indicated that combination treatment, using sulfonamides and DHFR/TS inhibitors, may be effective in treating neosporosis. (Am J Vet Res 1996;57:68-72)
Reactivity of purified complement component 3b with bovine neutrophils and modulation of complement receptor 1
Authors: Di Carlo Andrea L. , Paape Max J. , Miller Robert H.
Published: January 2024

Objective

To study binding of purified complement component C3b to bovine blood and mammary neutrophils (PMN) after various treatments and determine their ability to modulate receptor numbers.

Design

Cell isolation, activation, and flow cytometric studies.

Animals

Healthy lactating Holstein cattle.

Procedure

Complement component C3b (18,300 kd) was isolated from bovine serum by column chromatography, and flow cytometric assays using fluorescein isothiocyanate-labeled C3b were developed to evaluate binding to PMN complement receptor 1. Multiple substances were tested to determine their overall effect on C3b binding to PMN. Blood and milk PMN were isolated by differential centrifugation and exposed to optimal concentrations of recombinant human C5a, formyl-methyl leucyl phenylalanine, recombinant bovine interferon-γ, variable concentrations of phorbol myristate acetate (0.01 to 100 ng), calcium ionophore A23187, serum-opsonized zymosan, zymosan-activated serum (ZAS), zymosan-activated plasma (ZAP), and hydrocortisone acetate (25 and 70 ng). Additionally, mammary and blood PMN were preincubated in skim milk and whey.

Results

Variable concentrations of phorbol myristate acetate caused a dose-dependent increase in percentage of PMN binding C3b, and increased the amount of C3b bound per cell. Significant increases were observed after PMN treatment with calcium ionophore, serum opsonized zymosan, ZAS, and ZAP; conversely, incubation of PMN with hydrocortisone acetate resulted in reduced overall binding of C3b. Mammary PMN consistently bound more C3b, which was attributed to their activation during migration into the mammary gland. Binding of C3b was inhibited by skim milk. Activation of blood PMN with PMA, ZAS, and ZAP elicited larger responses than those observed for mammary PMN.

Conclusions

Modulation of complement receptors on bovine PMN is possible. Additionally, significant difference between the level of binding of C3b to blood and milk PMN, with milk PMN having higher binding, may be attributable to migration of PMN into the mammary gland, causing increased receptor expression.

Clinical Relevance

Contribution to a greater understanding of the role of complement in bovine immunologic systems, leading to testing for in vivo enhancement of bovine immune responses to invading pathogens.
Induction of protective immunity against transmissible gastroenteritis virus after exposure of neonatal pigs to porcine respiratory coronavirus
Authors: Wesley Ronald D. , Woods Roger D.
Published: January 2024

Objective

To test the ability of porcine respiratory coronavirus (PRCV) to induce protective immunity to antigenically related transmissible gastroenteritis virus (TGEV) in neonatal pigs.

Design

Neonatal pigs were exposed to PRCV when they were 2, 4, or 6 days old and challenge-exposed to virulent TGEV at 10 days of age.

Animals

34 hysterectomy-derived, colostrum-deprived pigs.

Procedure

After challenge exposure, clinical signs were observed, body weight, antibody response, and virus shedding were measured, and mortality was determined.

Results

After exposure to PRCV, principals had a slightly slower rate of weight gain than did controls; with 1 exception (a PRCV-exposed pig that was dyspneic for 1 day), principals and controls remained clinically normal until shortly after challenge exposure, when all pigs became listless and anorectic and developed watery diarrhea. However, by day 3, most of the pigs that had been exposed to PRCV when they were either 2 or 4 days old began to recover and most (15/18) survived. Conversely, the clinical condition of most of the other pigs worsened and most (14/16) died. Pigs exposed to PRCV when they were 2 or 4 days old also differed from all other pigs in that they had serum virus-neutralizing antibodies for PRCV and TGEV at the time of challenge exposure.

Conclusions

The PRCV can induce protective immunity to TGEV in neonatal pigs and such immunity develops at or about 6 days after exposure to PRCV. Moreover, protective immunity may be coincident with the appearance of virus-neutralizing antibody.

Clinical Relevance

Exposure to PRCV should enhance a TGE herd vaccination program.
Transcatheter modification of the atrioventricular node in dogs, using radiofrequency energy
Authors: Wright Kathy N. , Bright Janice M. , Cox James W. , McCracken Malcolm D.
Published: January 2024

Objective

To develop a protocol for reliably inducing atrioventricular (AV) block (ideally first- or second-degree), using radiofrequency energy.

Design

An electrosurgical unit was coupled to an ammeter, which was connected to the distal pole of an electrode catheter positioned at the AV node. Control settings had previously been calibrated to the power output in a circuit with a 100-ohm resistance.

Animals

10 clinically normal dogs.

Procedure

Transcatheter AV nodal modification was attempted, using progressive power applications of 10 to 20 W for progressive durations of 10 to 30 seconds. Atrioventricular nodal conduction and refractivity were measured before and 20 minutes and 1 month after ablation. Electrocardiograms were monitored throughout the 1-month period.

Results

Eight of the 10 dogs developed complete AV block, 1 developed stable 2:1 AV block, and another had no long-term change in AV nodal conduction. Four dogs attained their maximal degree of AV block in 2 to 5 days. Three of these had no AV nodal conduction changes until 2 to 4 days after ablation.

Conclusions

An electrosurgical unit can be economically modified for radiofrequency transcatheter ablation. Stable, incomplete AV block was rarely induced using this protocol, whereas complete AV block often developed. A major finding was frequent delay between energy delivery to the AV nodal region and induction of AV block.

Clinical Relevance

Induction of complete AV block using this technique, followed by permanent pacemaker placement, is an effective alternative to long-term antiarrhythmic treatment in animals with chronic atrial arrhythmias. Transcatheter ablation could be used to treat other forms of tachycardia, as it is in human medicine.
Cross-sectional evaluation of environmental, host, and management factors associated with risk of seropositivity to Ehrlichia risticii in horses of New York state
Authors: Atwill Edward R. , Mohammed Hussni O. , Lopez Jorge W. , McCulloch Charles E. , Dubovi Edward J.
Published: January 2024

Objectives

To locate counties within New York state with a high seroprevalence among the equine population, to determine host, management, and environmental factors that were associated with seropositivity to Ehrlichia risticii, and to determine evidence for arthropod- or helminth-mediated transmission of E risticii to horses.

Design

Cross-sectional study.

Sample Population

A random sample of 3,000 of the 39,000 equine operations in New York state was selected, and 2,587 horses from 511 operations were tested.

Procedure

Blood samples were collected from horses and tested for seropositivity, using the indirect fluorescent antibody technique. Data on each horse and each farm's management were obtained by personal interview. The significance of each factor on the risk of seropositivity was evaluated, using mixed-effect logistic regression.

Results

The seroprevalence among E risticii-nonvaccinated horses was 7.3%. The county-specific seroprevalence ranged from 0 to 27%, with higher-risk counties located at low elevation. Farms at higher risk for having seropositive horses were located predominately at low elevation with no bodies of water nearby.

Risk of seropositivity was associated with time spent in a stall or run-in shed, with frequency of application of fly spray, and, depending on duration of residency at the farm, with frequency of deworming with benzimidazole and pyrantel. Standardbreds were 2 to 3 times more likely to have been exposed, compared with Thoroughbreds. Depending on duration of residency at the farm, male and middle-age horses were at higher risk.

Up to 32% of the variance for a horse to test seropositive for E risticii on the logit scale was attributable to farm-level random effects, but the nested social group random effect was not significant.

Conclusions

Arthropods and helminths may have a role in the transmission of this disease. Several management factors may directly or indirectly modify the risk of exposure to E risticii, allowing for the possibility of additional control measures besides traditional vaccination strategies.(Am J Vet Res 1996;57:278-285 )
Kinetics of the humoral immune response to multiple treatments with exogenous gonadotropins and relation to ovarian responsiveness in domestic cats
Authors: Swanson William F. , Roth Terri L. , Graham Katerina , Horohov David W. , Godke Robert A.
Published: January 2024

Objective

To investigate ovarian responses and kinetics of gonadotropin-binding immunoglobulin production in domestic cats repeatedly treated with equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) at short or long treatment intervals.

Design

Queens were treated 3 or 4 times with a standard eCG/hCG regimen at short (49 to 57 days) or long (130 to 135 days) intervals and subjected to laparoscopy after each treatment to evaluate ovarian follicular development. Serial serum samples were assessed by ELISA for the presence of eCG-binding immunoglobulins.

Animals

11 clinically normal sexually mature female cats.

Results

Queens repeatedly stimulated with eCG/hCG at long intervals typically had no decrease (P > 0.05) in ovarian follicle production or in maturity of recovered oocytes, whereas queens treated at short intervals had reduced (P < 0.05) follicular development and compromised oocyte maturity by the third stimulation. For both interval groups, ELISA data indicated individual variability in seroconversion after eCG/hCG challenge exposure. In general, queens treated at short intervals had higher peak anti-eCG immunoglobulin titer than did queens treated at long intervals; high titer at the time of eCG/hCG injection, or rapid increases in titer immediately after injection were predictive (P < 0.05) of poor ovarian responses.

Conclusions

Results suggest that individual variability in immune responses and intervals between repeated gonadotropin treatments determine whether queens develop immunologically mediated ovarian refractoriness to exogenous gonadotropins. Intervals of at least 4 months between successive eCG/hCG treatments are recommended for assisted reproductive procedures in domestic and nondomestic cats.(Am J Vet Res 1996;57:302-307)
Involvement of (n-6) essential fatty acids and prostaglandins in liver lipid accumulation in Japanese quail
Authors: Murai Atsushi , Furuse Mitsuhiro , Okumura Jun-ichi
Published: January 2024

Objective

To investigate the involvement of (n-6) essential fatty acids, such as linoleic acid [18:2(n-6)] or γ-linolenic acid [18:3(n-6)], and of prostaglandins on liver lipid accumulation in Japanese quail.

Design

Effects of graded amounts of aspirin, which inhibits prostaglandin synthesis, on liver weight were determined in experiment 1. Experiment 2 was designed to clarify the effect of dietary essential fatty acid sources and inhibition of prostaglandin synthesis on the liver fat and fatty acid profile.

Animals

Female Japanese quail.

Procedure

In experiment 1, from 1 to 3 weeks of age, birds were fed ad libitum the essential fatty acids-free or linoleic acid-adequate (2%) diets with graded amounts of aspirin (0, 0.1, 0.2, and 0.4%). In experiment 2, from 1 to 4 weeks of age, birds were fed the same amount of essential fatty acids-free, linoleic acid-adequate, or γ-linolenic acid (0.4%) diets with (0.2%) or without aspirin.

Results

In experiment 1, in groups given the essential fatty acids-free diet, liver weight increased with an increase in dietary aspirin concentration. In experiment 2, γ-linolenic acid completely prevented liver triacylglycerol and cholesterol accumulation induced by the essential fatty acids-free diet. Aspirin treatment significantly lowered plasma prostaglandin F2α concentration, but did not affect liver lipid concentrations. In groups fed the essential fatty acids-free diets, however, aspirin treatment increased liver weight and liver triacylglycerol concentration by 20 and 40%, respectively.

Conclusions

γ-Linolenic acid or its metabolites, but not linoleic acid itself, are important factors in reducing fatty liver in Japanese quail with the essential fatty acids-deficient condition.(Am J Vet Res 1996;57:342-345)
Impact of an orally administered insect growth regulator (lufenuron) on flea infestations of dogs in a controlled simulated home environment
Authors: Smith Ronald D. , Paul Allan J. , Kitron Uriel D. , Philip John R. , Barnett Sharron , Piel Margaret J. , Ness Robert W. , Evilsizer Melody
Published: January 2024

Objective

To evaluate the ability of lufenuron to control cat flea (Ctenocephalides felis felis) populations on dogs under conditions simulating a naturally infested home environment.

Design

2 treatment and 2 control groups of dogs. Treated dogs received lufenuron in tablet form monthly, and controls received excipient. Dogs had unrestricted access to indoor (carpeted) and outdoor (grassy) environments in which self-propagating flea populations had been established.

Animals

17 adult female Beagles.

Procedure

Dogs were monitored for 77 days after initial infestation with fleas and 70 days after initial treatment. Efficacy of the drug was calculated on the basis of absolute reduction in flea counts and as a percentage of control.

Results

Lufenuron administration caused a statistically significant (P < 0.05) reduction in flea burdens in treated dogs, compared with controls. Initiation of treatment 7 days after infestation resulted in 75% control of F1-generation and 97% control of F2-generation fleas over a 70-day posttreatment period.

Conclusions

Lufenuron was highly effective in reducing flea populations on dogs. The time required for control will vary with the duration (generation time) of the flea reproductive cycle and, hence, the geographic area in which the product will be used. The experimental results are most relevant to use of the product for control of an existing flea population in the Midwest. (Am J Vet Res 1996;57:502–504)
Evaluation of propofol for general anesthesia in premedicated horses
Authors: Mama K. R. , Steffey E. P. , Pascoe P. J.
Published: January 2024

Objective

To evaluate selected hemodynamic, respiratory, and behavioral responses to propofol in horses premedicated with xylazine or detomidine.

Design

Xylazine (0.5 and 1.0 mg/kg of body weight) was administered IV on different days to each of 6 horses prior to IV administration of propofol (2 mg/ kg). In a second group of 6 horses, detomidine (15 and 30 µg/kg) was similarly studied.

Animals

2 groups of 6 mature healthy horses.

Procedure

Rectal temperature, heart and respiratory rates, arterial blood gas tensions, and direct arterial blood pressures were recorded before and at fixed intervals after drug administration. Induction and recovery events were quantitatively and qualitatively assessed. Cardiopulmonary and behavioral data to follow were statistically analyzed (P< 0.05).

Results

Heart rate decreased in dose-dependent manner from a mean (± SD) of 39.5 ± 5.1 beats/min after xylazine and detomidine. Second-degree atrioventricular dissociation was commonly seen at the higher drug doses. After propofol administration, heart rate either transiently increased or was less depressed early in recumbency, compared with predrug values. Direct arterial blood pressures varied inconsistently from predrug values. Mean arterial carbon dioxide tension tended to increase after drug administration (significance variable) from predrug values of 42 to 46 mm of Hg in both drug groups. After xylazine or detomidine administration, arterial oxygen tension decreased significantly from predrug values of 97 to 103 mm of Hg. The magnitude and duration of decrease was dose-dependent and greatest during recumbency.

Behavioral responses to anesthetic induction were variable, but horses were uniformly calm and coordinated during recovery. Recumbency time increased in reponse to the higher dose of either premedicant drug. Mean (± SD) times to standing were 25.02 ± 4.42 and 35.57 ± 6.83 minutes for the low and high doses of xylazine, respectively and 41.04 ± 11.21 and 52.64 ± 14.67 minutes for the low and high doses of detomidine, respectively.

Conclusion

Neither xylazine nor detomidine prevented excitation associated with propofol injection in horses.

Clinical Relevance

Xylazine- or detomidine-propofol combinations likely will not replace common anesthetic induction techniques for horses. However, recovery characteristics associated with propofol encourage further study in horses. (Am J Vet Res 1996;57:512–516)
Regulation of glycosaminoglycan metabolism by bone morphogenetic protein-2 in equine cartilage explant cultures
Authors: Loredo Grace A. , MacDonald Melinda H. , Benton Hilary P.
Published: January 2024

Objective

To investigate whether recombinant human bone morphogenetic protein-2 (rhBMP-2) regulates glycosaminoglycan (GAG) synthesis and release from equine articular cartilage explant cultures.

Design

Equine articular cartilage explants were maintained in vitro for 7 days in the presence of 0 (control), 1, 10, or 100 ng of rhBMP-2/ml. Synthesis and release of GAG were assessed as measures of production and degradation of the extracellular matrix, respectively.

Animals

6 horses (age range, 2 to 25 years old) without clinically detectable musculoskeletal abnormalities.

Procedure

Rate of synthesis of GAG was assessed by incorporation of [35S]sulfate during the final 24 hours of the 7-day incubation period. Release of GAG was assessed on days 3, 6, and 7, using 1,9-dimethylmethylene blue

Results

Explants from all 6 horses had a significant (P = 0.05) increase in release of GAG in response to incubation with 100 ng of rhBMP-2/ml. There was a significant (P = 0.05) decrease in GAG synthesis in explants from only 2 of the 6 horses at the same concentration of rhBMP-2. There was no significant age correlation between responsive and nonresponsive horses.

Conclusions

A concentration of 100 ng of rhBMP-2/ml stimulates GAG release from explant cultures of equine articular cartilage. The data suggest that bone morphogenetic proteins may be potential regulators of equine cartilage degradation and repair.

Clinical Relevance

Surgical procedures that damage subchondral bone may stimulate generation of improved cartilage-like tissue. It is, therefore, crucial to understand how bone-derived factors may influence cartilage metabolism in horses. (Am J Vet Res 1996;57:554–559)
Viral status and antibody response in cattle inoculated with recombinant bovine leukemia virus-vaccinia virus vaccines after challenge exposure with bovine leukemia virus-infected lymphocytes
Authors: Cherney T. M. , Schultz R. D.
Published: January 2024

Objective

To determine the bovine leukemia virus (BLV) antibody response and infectivity status in BLV-vaccinated cattle after challenge exposure with BLV-infected lymphocytes.

Design

Steers were inoculated with vaccinia virus constructs expressing the gag, pol, and env genes of the BLV or the env gene only of the BLV genome, then challenge exposed with BLV-infected lymphocytes. The steers' BLV antibody and infectivity status was monitored.

Animals

Fifteen 8- to 9-month-old Holstein steers previously determined to be BLV antibody and BLV negative.

Procedure

1 month after second after inoculation, steers were challenge exposed with 106 BLV-infected lymphocytes from a highly infective BLV-positive cow. Serum and blood lymphocytes were obtained regularly for 6 months. The agar gel immunodiffusion assay, ELISA, and serum neutralization assay were used to detect BLV antibody in serum of steers. The sheep infectivity and syncytium-forming assays were used to determine the viral status of the steers.

Results

Differences were seen in antibody responses between the BLV-vaccinated and non-BLV-vaccinated control groups. All cattle were susceptible to infection when challenge exposed with BLV-infected lymphocytes.

Conclusion

Despite the enhanced immune response in the BLV-vaccinated cattle after challenge exposure, none of the BLV-vaccinated cattle was protected from BLV infection.

Clinical Relevance

Vaccination is not an effective way to protect cattle from BLV infection. (Am J Vet Res 1996;57:812–818)
Effects of dietary n-3 fatty acid supplementation versus thromboxane synthetase inhibition on gentamicin-induced nephrotoxicosis in healthy male dogs
Authors: Grauer Gregory F. , Greco Deborah S. , Behrend Ellen N. , Fettman Martin J. , Mani Indu , Getzy David M. , Reinhart Gregory A.
Published: January 2024

Objective

To evaluate the protective effects of dietary n-3 fatty acid supplementation versus treatment with a thromboxane synthetase inhibitor (TXSI) in dogs given high-dose gentamicin.

Design

Clinicopathologic and renal histopathologic changes induced by gentamicin (10 mg/kg of body weight, IM, q 8 h, for 8 days) were compared in dogs fed an n-3 fatty acid-supplemented diet containing a fatty acid ratio of 5.7:1 (n-6:n-3), dogs treated with CGS 12970 (a specific TXSI given at 30 mg/kg, PO, q 8 h, beginning 2 days prior to gentamicin administration), and control dogs. The TXSI-treated and control dogs were fed a diet with a fatty acid ratio of 51.5:1 (n-6:n-3). Both diets were fed beginning 42 days prior to and during the 8-day course of gentamicin administration.

Animals

Eighteen 6-month-old male Beagles, 6 in each group.

Results

After 8 days of gentamicin administration, differences existed among groups. Compared with n-3-supplemented and control dogs, TXSI-treated dogs had higher creatinine clearance. Both TXSI-treated and n-3-supplemented dogs had higher urinary prostaglandin E2 and E3 (PGE2/3) and 6-keto prostaglandin F1α (PGF1α) excretion, compared with control dogs. Urinary thromboxane B2 (TXB2) excretion was higher in n-3-supplemented and control dogs, compared with TXSI-treated dogs. Urine PGE2/3-to-TXB2 and PGF1α-to-TXB2 ratios were increased in TXSI-treated dogs, compared with n-3-supplemented and control dogs, and these ratios were increased in n-3-supplemented dogs, compared with control dogs. In addition, TXSI-treated and n-3-supplemented dogs had lower urinary protein excretion, compared with control dogs. Proximal tubular necrosis was less severe in TXSI-treated dogs, compared with control dogs.

Conclusion

Treatment with CGS 12970 prior to and during gentamicin administration prevented increases in urinary TXB2 excretion and reduced nephrotoxicosis.

Clinical Relevance

Increased renal production/excretion of thromboxane is important in the pathogenesis of gentamicin-induced nephrotoxicosis. (Am J Vet Res 1996;57:948–956)
Histomorphometric and angiographic analysis of bone healing in the humerus of pigeons
Authors: West P. G. , Rowland G. R. , Budsberg S. C. , Aron D. N.
Published: January 2024

Objective

To evaluate the vascular supply and quantitatively compare the periosteal and endosteal callus formed during fracture healing.

Design

36 pigeons were allotted to 2 groups. In each bird, 1 humerus was surgically osteotomized. The wing with the fractured humerus in birds of the first group was infused with a microparticle barium solution, and the humerus was harvested for angiography. Pigeons of the second group were injected with the labels oxytetracycline and calcein. The fractured humerus in each of these birds was harvested for histomorphometry.

Animals

36 nine-month-old pigeons, consisting of 19 male and 17 female birds.

Procedure

1 humerus from each of the 36 pigeons was osteotomized in the center of the bone by use of an obstetrical wire. All fractured wings were placed in a figure-of-8 bandage after surgery. The specimens harvested for angiography were decalcified, radiographed, and sectioned for H&E-stamed tissue slides. Humeruses harvested for histomorphometry were cross-sectioned for tissue slides, which were measured, using a morphometric analyzing system for original and new bone areas.

Results

A continuous intramedullary circulation was not present at any point in the healing process, although 2 of the 42-day-old fractures had a bridging callus. Quantitatively, the periosteal surface formed the largest amount of callus, though the endosteal surface was also active.

Conclusions

Reformation of the intramedullary circulation may not be imperative for osseous union of the pigeon humerus. Fluorochrome labels cannot be accurately measured at the fracture site. However, subjective evaluation of the endosteal surface indicates it is active during the fracture-healing process even though the periosteal surface provides the largest amount of callus formation.

Clinical Relevance

Figure-of-8 coaptation is contraindicated for humeral fractures. The endosteal surface's contribution to the healing process should be considered when avian humeral fractures are stabilized. (Am J Vet Res 1996;57:1010–1015)