bluuebunny/crossref_metadata_2025 huggingface dataset:
Air- and bone-conduction brainstem auditory evoked potentials and flash visual evoked potentials in cats
Authors: Strain George M. , Tedford Bruce L. , Littlefield-Chabaud Martha A. , Treviño Lisa T.
Published: January 2024

Objective

-To document normal values for air- and bone-conducted brainstem auditory evoked potentials (BAEP) and for flash visual evoked potentials (VEP) in cats.

Animals

10 mixed-breed cats (5 males) with normal physical, neurologic, otoscopic, and funduscopic examination results.

Procedure

BAEP in response to air- and bone-conducted click stimuli and VEP in response to flash stimuli were recorded to document species normative data. Mean and SD values were calculated for amplitudes and latencies of 4 peaks in the BAEP in response to air- and bone-conducted stimuli, and for latencies to 5 peaks and the 4 associated peak-to-peak amplitudes in the VEP.

Results

BAEP peak latencies increased and peak amplitudes decreased with decreasing stimulus intensity. Latencies were shorter for bone-conducted stimuli owing to the shorter transit time to the cochlea through bone, compared with air, but there were no differences for interpeak latencies. The BAEP and VEP recordings were similar to those reported for cats in other reports and were similar to those seen in other species.

Clinical Relevance

Normative data will permit performance of noninvasive electrodiagnostic evaluation of feline auditory and visual systems. (Am J Vet Res 1998;59:135–137)
Tumor necrosis factor-α in pregnant cattle after intravenous or subcutaneous vaccination with Brucella abortus strain RB51
Authors: Palmer Mitchell V. , Elsasser Theodore H. , Cheville Norman F.
Published: January 2024

Objective

To determine the influence of brucellosis vaccination on tumor necrosis factor-α (TNF-α) con-centrations in pregnant cattle and the possible role of the bovine placenta in TNF-α production.

Animals

Polled Hereford heifers obtained from a nonvaccinated, brucellosis-free herd and bred at 16 to 27 months at age. All cattle were seronegative for Brucella abortus by results of the standard tube agglutination test.

Procedure

At 6 months' gestation, cattle were vaccinated IV with B abortus strain RB51 (n = 10), SC with B abortus strain RB51 (n = 5), or SC with B abortus strain 19 (n = 5); controls received pyrogen-free saline solution SC (n = 2). Blood samples were collected periodically for TNF-α assays. At necropsy, 8 to 12 weeks after vaccination, placental fluids and fetal blood were collected for TNF-α analysis and placental tissues were collected for immunohistochemical detection of TNF-α.

Results

Radioimmunoassays indicated no increase in TNF-α concentration in blood from IV or SC vaccinated cattle, compared with controls. Similarly, TNF-α concentrations in amniotic and allantoic fluids from SC vaccinated cattle were not different from values for controls. Although only IV vaccinated cattle developed placentitis, immunohistochemical analysis for TNF-α revealed increased immunoreactivity within placental trophoblastic epithelial cells of SC and IV vaccinated cattle.

Conclusions

SC vaccination for prevention of brucellosis, using recommended adult dosages, does not result in increase of TNF-α concentration in plasma, serum, or placental fluids; however, vaccination of pregnant cattle stimulates trophoblastic epithelial cells to express TNF-α, although the physiologic and quantitative importance of this expression remains unknown. (Am J Vet Res 1998;59:153–156)
Evaluation of analgesia induced by epidural administration of medetomidine to cows
Authors: Lin Hui-Chu , Trachte Elizabeth A. , DeGraves Fred J. , Rodgerson Dwayne H. , Steiss Janet E. , Carson Robert L.
Published: January 2024

Objective

To evaluate analgesic effects after epidural administration of medetomidine to cows, compared with effects of lidocaine hydrochloride and 0.9% NaCI solution.

Animals

6 adult beef cows.

Procedure

3 treatments were administered to each cow, with a 1-week interval between subsequent treatments. Treatments consisted of 5 ml of physiologic saline (0.9% NaCI) solution; 0.2 mg of lidocaine/kg of body weight, not to exceed 100 mg (5 ml); and 15 μg of medetomidine/kg, diluted with 0.9% NaCI solution to provide a volume of 5 ml. Epidural injections were given in the first or second coccygeal space. Heart rate, respiratory rate, and arterial blood pressure values were recorded before injection, 5 and 10 minutes after injection, and at 10-minute intervals thereafter. Onset and duration of analgesia, sedation, and ataxia were recorded. A repeated-measures ANOVA was used to detect differences between treatments.

Results

Epidural administration of 0.9% NaCI solution did not induce analgesia. Lidocaine induced analgesia within 5 to 20 minutes, which lasted 10 to 115 minutes (mean ± SD, 43.3 ± 37.2 minutes). Heart rate decreased during lidocaine-induced analgesia. Heart and respiratory rates decreased, but blood pressure remained unchanged, after medetomidine administration. Medetomidine induced analgesia within 5 to 10 minutes, which lasted 412 ± 156 minutes. Mild to moderate sedation and moderate ataxia were observed. Two cows became recumbent, but were easily coaxed to stand. Medetomidine-induced salivation and increased frequency of urination were observed in all cows.

Conclusions and Clinical Relevance

Epidural administration of medetomidine induced prolonged analgesia that was suitable for perineal surgery, post-operative analgesia, and relief of continuous straining. (Am J Vet Res 1998;59:162–167)
Association between bronchoalveolar lavage cytologic features and airway reactivity in horses with a history of exercise intolerance
Authors: Hoffman A. M. , Mazan M. R. , Ellenberg S.
Published: January 2024

Objective

To correlate indices of airway reactivity to bronchoalveolar lavage (BAL) fluid cytologic features in horses with a recent decline in exercise tolerance.

Animals

20 actively working horses from 2 to 24 years old.

Procedure

Bronchoalveolar lavage fluid samples were obtained and analyzed. Forced oscillatory mechanics (1-7 Hz) technique was used for measurements of total respiratory system resistance (RRS), compliance (CRS), and resonant frequency (fres). Changes in RRS (1 Hz) during histamine challenge were used to generate histamine dose-response curves, from which the provocative concentrations that evoked a 75 or 100% increase in baseline RRS (PCRRS75 and PCRRS100, respectively) were determined. Age, sex, baseline lung mechanics, and BAL cytologic findings were correlated with PCRRS75 and PCRRS100.

Results

No horse of the study had clinical signs or history of obstructive pulmonary disease or increased percentage (> 7%) of neutrophils in bronchoalveolar lavage fluid samples. Mean (± SEM) RRS, CRS, and fres were 0.67 ± 0.06 cm of H2O/L/s, 0.52 ± 0.04 L/cm H2O, and 2.46 ± 0.02 Hz, respectively. There was no correlation between age or sex, and RRS, CRS, fres, PCRRS75, or PCRRS100. There was a significant correlation (rs = −0.78, P < 0.001) between percentage of BAL fluid mast cells and PCRRS75 or PCRRS100, but correlation with other cell types and indices of airway reactivity were not observed.

Conclusion

The strong association between mast cell percentage in BAL fluid and airway reactivity in this group suggests that mast cell products may contribute to bronchospasm, airway wall thickening, and/or loss of elastic recoil, which underlie airway hyperreactivity. Alternatively, mast cells may contribute to nonspecific airway reactivity in horses through unknown mechanisms. (Am J Vet Res 1998;59:176–181)
Effect of different full-limb casts on in vitro bone strain in the distal portion of the equine forelimb
Authors: Hopper Scott A. , Schneider Robert K. , Ratzlaff Marc H. , White Karl K. , Johnson Craig H.
Published: January 2024

Objective

To determine the ability of a full-limb transfixation pin cast to protect the distal portion of the equine forelimb from weight-bearing forces by measuring bone strain in vitro on cadaver limbs loaded in a mechanical testing machine.

Sample Population

6 forelimbs from 6 horses.

Procedure

Each limb was instrumented with 3 unidirectional metal foil electrical resistant strain gauges. Gauges were placed on the dorsal aspect of the distal portion of the radius and the mid-dorsal portion of the cortex of the third metacarpal bone and the first phalanx. Each limb was tested 3 times, once supported with a transfixation pin cast, once supported by a standard full-limb cast, and finally, uncast. The limbs were tested in a mechanical testing machine under axial loads ranging from 100 to 1,000 lb, and bone strains were recorded at each load.

Results

Compared with values for the uncast limb, the transfixation pin cast and the standard full-limb cast significantly (P < 0.001) reduced bone strain on the distal portion of the radius, third metacarpal bone, and first phalanx. Compared with the standard full-limb cast, the transfixation pin cast significantly (P < 0.001) reduced bone strain on the first phalanx.

Conclusion and Clinical Relevance

Compared with the standard full limb cast, the full-limb transfixation pin cast is more protective of the first phalanx. (Am J Vet Res 1998;59:197–200)
Water content and glycosaminoglycan disaccharide concentration of the canine meniscus
Authors: Stephan John S. , McLaughlin Ron M. , Griffith Gary
Published: January 2024

Objective

To determine the regional composition of water and glycosaminoglycan (GAG) disaccharides of the canine meniscus.

Sample Population

52 menisci from the stifle of dogs.

Procedure

Regional sections of each meniscus were weighed, dried, and reweighed to determine water content. Dried tissue specimens were subjected to enzymatic digestion. Analysis and quantification of disaccharide degradation products were performed, using high-performance liquid chromatography.

Results

Water content was approximately 65% in polar and central regions of the canine meniscus. Water content of the central region of the lateral meniscus was significantly higher than that of the medial meniscus (P = 0.0090). Chondroitinase digestion of canine meniscal tissue yielded detectable ΔDi-HA, ΔDi-4S, and ΔDi-6S GAG disaccharides. Disaccharides specific to dermatan sulfate and chondroitin D or E sulfate were not detected. Concentrations of ΔDi-4S and ΔDi-6S were significantly greater in the lateral central region, compared with the medial central region (P = 0.0005 and 0.0002, respectively).

Conclusion

Water content and ΔDi-4S and ΔDi-6S concentrations were significantly lower in the central region of the medial meniscus, compared with the central region of the lateral meniscus. Reduced tissue hydration of the medial central region may have been a direct result of its overall decrease in total GAG content.

Clinical Relevance

The ability to evaluate subtle differences in tissue GAG composition by analytical measurement of their constituent disaccharides may aid in the understanding of the complex material properties of the normal and diseased meniscus, which may be applied to the study of meniscal healing and biomechanics. (Am J Vet Res 1998;59:213–216)
Effect of infusion of hypertonic saline solution on conscious heifers with hypoxemia caused by endotoxin infusion
Authors: Suzuki Kazuyuki , Ajito Tadaharu , Iwabuchi Shigehiro
Published: January 2024

Objective

To compare effects of IV infusion of a small volume (5 ml/kg of body weight) of hypertonic saline (7.2% NaCl) solution (HSS) and IV infusion of an equivalent volume of isotonic saline (0.9% NaCl) solution (ISS) on arterial blood gases in conscious heifers with hypoxemia caused by endotoxin infusion.

Animals

9 Holstein heifers.

Procedure

All heifers received 2.0 μg of endotoxin/kg, IV, during a 5-minute period. Twenty-five minutes after endotoxin infusion, 3 heifers received ISS, 3 received HSS, and the remaining 3 did not receive fluids (control). Heifers were monitored for 150 minutes after initiation of fluid replacement. Arterial blood gases, blood pressure, and serum electrolyte concentrations were measured.

Results

Endotoxin administration had a profound effect on pulmonary function, causing severe hypoxemia accompanied by a significant decrease in the partial pressure of oxygen (PaO2) and a significant increase in the arterial-alveolar O2 gradient (P[A-a]O2). Cattle in the HSS group had progressive and significant increases in PaO2 and O2 saturation, compared with the other groups. The P(A-a)O2 values for the control and ISS groups were slightly decreased until 150 minutes after initiation of fluid replacement; however, HSS infusion induced a progressive and significant decrease in P(A-a)O2 for the remainder of the experimental period.

Conclusions and Clinical Relevance

Rapid infusion of HSS can successfully resuscitate conscious cattle with induced pulmonary dysfunction. Infusion of HSS may be beneficial for initial resuscitation of cattle with naturally developing bovine respiratory disease complex. (Am J Vet Res 1998;59:452–457)
Pharmacokinetics of cefepime and comparison with those of ceftiofur in horses
Authors: Guglick Mary Ann , MacAllister Charles G. , Clarke Cyril R. , Pollet Robert , Hague Christinia , Clarke Jean Μ.
Published: January 2024

Objective

To determine pharmacokinetics of IV, IM, and oral administration of cefepime in horses and to compare pharmacokinetics of IM administration of cefepime with those of ceftiofur sodium.

Animals

6 clinically normal adult horses.

Procedure

Horses received 3 doses of cefepime (11 mg/kg of body weight, PO; 2.2 mg/kg, IV; and 2.2 mg/kg, IM) and 1 dose of ceftiofur (2.2 mg/kg, IM). Two horses also received l-arginine, PO and IV, at doses identical to those contained in the cefepime dihydrochloride-l-arginine preparations previously administered. Blood samples were collected for 24 hours after administration of cefepime or ceftiofur and were assayed for cefepime and ceftiofur concentrations.

Results

Pharmacokinetic analysis of disposition data indicated that IV administration data were best described by a 2-compartment open model, whereas IM administration data were best described by a 1-compartment absorption model. Median elimination half-life and volume of distribution after IV administration of cefepime were 125.7 minutes and 225 ml/kg, respectively. After IM administration of cefepime, mean maximal plasma concentration of (8.13 μg/ml) was reached at a mean time of 80 minutes. Absorption of cefepime after IM administration was complete, with a median bioavailability of 1.11. Intramuscular administration of ceftiofur resulted in similar mean maximal plasma concentration (7.98 μg/ml) and mean time to this concentration (82 minutes). Cefepime was not detected in samples collected after oral administration. Adverse effects consisting principally of gastrointestinal disturbances were observed after oral and IM administration of cefepime and after 1 IM administration of ceftiofur.

Conclusions and Clinical Relevance

Cefepime, administered IV or IM at a dosage of 2.2 mg/kg, every 8 hours is likely to provide effective antibacterial therapy for cefepime-sensitive organisms in horses. Further studies are needed to evaluate adverse effects on the gastrointestinal tract. (Am J Vet Res 1998;59:458–463)
Changes in plasma atrial natriuretic peptide concentration in exercising horses in relation to hydration status and exercise intensity
Authors: Nyman Sara , Kokkonen Ulla-Maija , Dahlborn Kristina
Published: January 2024

Objective

To investigate effects of hydration status and exercise intensity on plasma atrial natriuretic peptide (ANP) concentration in exercising horses.

Animals

4 trained Standardbreds.

Procedure

Horses performed a 40-minute exercise test at 65 to 70% maximal heart rate (HRmax; no incline) and a 12-minute test at approximately 90% HRmax (3.5° incline). The 40-minute test was performed with ad libitum access to drinking water (normohydration), after water had been withheld for 24 hours (dehydration), and 30 minutes after 12 L of water at body temperature had been given via nasogastric tube (hyperhydration). The 12-minute test was only performed with normohydrated horses.

Results

Plasma ANP concentration was higher toward the end of exercise during hyperhydration than during the other 2 hydration states, and the area under the plasma ANP concentration curve was significantly greater during hyperhydration than during dehydration. The maximal plasma ANP value induced during the 12-minute test was similar to that of the 40-minute test. After the 12-minute test, plasma ANP concentration did not decrease during the first 30 minutes of recovery, whereas after the 40-minute test, plasma ANP concentration decreased by approximately 30% during the same period.

Conclusions

Hydration status can affect plasma ANP concentration in horses during submaximal exercise. Maximal plasma ANP concentration was similar at the 2 exercise intensities studied, but the postexercise return to baseline values differed.

Clinical Relevance

Changes in hydration status can cause alterations in plasma concentration of ANP, one of the hormones involved in the control of cardiovascular functions during exercise. (Am J Vet Res 1998;59:489–494)
Evaluation of antemortem polymerase chain reaction and serologic methods for detection of Lawsonia intracellularis-exposed pigs
Authors: Knittel Jeffrey P. , Jordan Dianna Μ. , Schwartz Kent J. , Janke Bruce H. , Roof Michael B. , McOrist Steven , Harris D. L.
Published: January 2024

Objective

To evaluate polymerase chain reaction (PCR) for detection of Lawsonia intracellularis DNA in feces and an indirect fluorescent antibody test (IFAT) for detecting serum IgG antibodies in pigs exposed to L intracellularis.

Animals

15 seven-week-old pigs and 42 three-week-old pigs.

Procedure

During 3 experiments, 23 pigs were inoculated with a pure culture of L intracellularis, 31 pigs served as noninoculated controls, and 3 pigs were used as sentinels. Fecal shedding of L intracellularis was monitored by use of PCR analysis at 7-day intervals. At euthanasia, the ileum was obtained for PCR and histologic analyses. Serum was obtained at 7-day intervals for use in the IFAT.

Results

Polymerase chain reaction analysis detected L intracellularis DNA in the feces of 39% of the inoculated pigs; by postinoculation days 21 to 28, 90% of inoculated pigs developed IgG antibodies detected by IFAT. Neither L intracellularis DNA nor IgG antibodies were detected in any of the noninoculated control pigs at euthanasia. Sera from pigs inoculated with enteric pathogens other than L intracellularis did not contain detectable antibodies that reacted with L intracellularis by use of the IFAT.

Conclusion

The IFAT for L intracellularis IgG antibody detection appeared to be a more sensitive antemortem test for detecting pigs experimentally infected with L intracellularis than was a PCR method for direct detection of the organism in the feces.

Clinical Relevance

Not all animals that are infected with L intracellularis shed the organism in feces at detectable amounts. (Am J Vet Res 1998;59:722-726)
Detection of Staphylococcus aureus in milk by use of polymerase chain reaction analysis
Authors: Khan M. A. , Kim C-H. , Kakoma I. , Morin E. , Hansen R. D. , Hurley W. L. , Tripathy D. N. , Baek B. K.
Published: January 2024

Objective

To evaluate polymerase chain reaction (PCR) analysis for detection of Staphylococcus aureus (nuc gene) in fresh and formalin-preserved milk.

Sample Population

Samples from 80 lactating sheep and 100 lactating dairy cows.

Procedure

4 lactating sheep were inoculated with S aureus by intramammary infusion. A set of primers specific for the nuc gene of S aureus was used to develop a PCR technique, and modification of the rapid boil method was used to isolate bacterial DNA. Milk was obtained from experimentally infected sheep before and after infusion with S aureus, and from the 100 cows and remaining 76 sheep. Samples were screened by bacteriologic culture and PCR. To validate the PCR assay, S aureus or other pathogens were added to distilled water and “normal” sheep milk samples, with and without formalin.

Results

The PCR assay was 100% specific for S aureus when known negative and positive samples were tested. Sensitivity was 100% for samples with added S aureus or other pathogens. Sensitivity was lower for samples obtained from experimentally infected sheep, but increased from 53% to 90% with increased washing of target DNA.

Conclusions

The PCR technique based on the nuc gene is able to detect S aureus in sheep milk yields results faster than does traditional culturing, is highly specific, and is able to detect S aureus in formalin-fixed milk samples.

Clinical Relevance

The assay is particularly suitable for analysis of samples shipped or stored without refrigeration. Although antibiotics in milk may inhibit growth in culture, they should not affect the results of the PCR assay. (Am J Vet Res 1998;59:807–813)
Interferon-γ and interleukin 4 gene expression in cows infected with Mycobacterium paratuberculosis
Authors: Sweeney Raymond W. , Jones Douglas E. , Habecker Perry , Scott Phillip
Published: January 2024

Objective

To determine whether clinical progression of paratuberculosis in cattle was associated with alterations in cytokine gene expression in affected tissues.

Animals

5 uninfected adult Holstein cows, 7 adult Holstein cows naturally infected with Mycobacterium paratuberculosis that did not have clinical signs of disease, and 4 adult Holstein cows naturally infected with M paratuberculosis that had progressive clinical signs of infection.

Procedure

Samples of ileum and cecal lymph nodes were obtained from each animal at the time of slaughter. A reverse transcriptase-competitive polymerase chain reaction assay was used to determine mRNA expression of interferon-γ (IFN-γ) and interleukin 4 in each sample.

Results

Interferon-γ gene expression was significantly higher in ileum and cecal lymph node samples from subclinically infected cows than from clinically infected cows.

Conclusions and Clinical Relevance

Progression of paratuberculosis to clinical stages is associated with reduced expression of IFN-γ at site of infection. If immune response to M paratuberculosis can be manipulated so that IFN-γ expression is increased, resistance to infection in cattle might be enhanced. (Am J Vet Res 1998;59:842–847)
Effect of intravenous calcium administration on gentamicin-induced nephrotoxicosis in ponies
Authors: Brashier Michael K. , Geor Raymond J. , Ames Trevor R. , O'Leary Terrance P.
Published: January 2024

Objective

To determine whether supplemental IV calcium administration would attenuate or prevent gentamicin-induced acute renal failure, defined as an increase in serum creatinine concentration ≥ 50% above baseline.

Animals

10 healthy pony mares.

Procedure

Pony mares were randomly assigned to receive calcium at a dosage of 20 mg/kg of body weight or saline solution IV, twice daily for 14 days. All pony mares received gentamicin at a dosage of 20 mg/kg IV every 8 hours for 14 days. Gentamicin pharmacokinetic, serum biochemical, and urinalysis data were measured every other day for the 14-day study period. Renal histologic examination was performed, and results were scored at the end of the 14-day period.

Results

4 of 5 mares not receiving calcium supplementation developed acute renal failure. Only 1 of the 5 mares receiving calcium supplementation developed acute renal failure. Over the course of the study, pony mares receiving calcium supplementation had significantly fewer changes in urinalysis variables, and significantly less microscopic renal damage.

Conclusion

Daily IV administration of calcium attenuated gentamicin-induced acute renal failure.

Clinical Relevance

Calcium supplementation may help diminish the risk of acute renal failure associated with aminoglycoside antibiotics. (Am J Vet Res 1998;59:1055–1062)
Detection of milk antibiotic residues by use of screening tests and liquid chromatography after intramammary administration of amoxicillin or penicillin G in cows with clinical mastitis
Authors: Anderson Kevin L. , Moats William A. , Rushing John E. , O'Carroll Julia M.
Published: January 2024

Objective

To compare results of 6 commercially available milk antimicrobial screening tests with results of liquid chromatography (LC) when testing milk samples from individual cows treated for mild clinical mastitis by intramammary (IMM) infusion with amoxicillin or penicillin G.

Animals

6 cows with noninduced clinical mastitis: 3 treated by IMM infusion with amoxicillin and 3 treated by IMM infusion with penicillin G.

Procedure

Composite milk samples were collected before, during, and after treatment. Samples were assayed by use of the screening tests and their results and those of LC were compared. The LC results were assumed to represent the true result.

Results

Results of screening tests compared well with results of LC, with agreement of 94%. Positive screening test results for samples containing drug values below the established tolerance or safe level, as evaluated by LC, were obtained from 2 cows in which abnormal milk, as well as marked increases in composite milk somatic cell count, were observed. With the exception of 1 test in 1 cow, all screening tests had negative results at the end of the labeled milk-withholding time.

Conclusions and Clinical Implications

On the basis of results of the limited sample reported, the screening tests appeared to provide good agreement overall, compared with LC results, when testing milk of individual cows treated by IMM infusion with amoxicillin or penicillin G. Positive screening test results for milk samples containing amoxicillin or penicillin G at values below the established tolerance or safe level, as evaluated by LC, may occasionally be obtained. (Am J Vet Res 1998;59:1096-1100)
Comparison of radiographic and necropsy findings of lung lesions in calves after challenge exposure with Pasteurella multocida
Authors: Jones Gary F. , Feeney Daniel A. , Mews Cindy
Published: January 2024

Objectives

To test suitability of radiographic evaluation of lung lesions as a substitute for lung lesion scores derived by examination at necropsy in challenge-exposure models of bovine pneumonia.

Animals

10 calves selected by body weight from 20 multiple-source male Holstein calves approximately 1 to 2 months old enrolled in a Pasteurella multocida challenge-exposure study.

Procedure

Calves were paired on the basis of weight and randomly assigned within pairs to vaccine or control (saline solution) group. By use of deep tracheal cannulation, calves were challenge exposed with a culture of virulent P multocida, observed for 10 days, euthanatized, and necropsied, and the lungs were scored for pneumonic lesions. Radiographic views of the lung fields of the calves were taken before challenge exposure and before necropsy and were evaluated for alveolar disease by a veterinary radiologist. Lung lesion scores were compared with radiographic evaluations.

Results

There was a strong and significant correlation (R2 = 0.91, P < 0.001) between results of the evaluation of postchallenge-exposure radiographs and necropsy results. There also was also strong and significant correlation (R2 = 0.90, P < 0.001) between evaluation of the prechallenge-exposure radiographs and necropsy results.

Conclusions

Radiographic evaluation of lung lesions correlates well with lung lesions found at necropsy. The findings emphasize the need for caution in interpreting the results of challenge-exposure studies of bovine respiratory tract disease in which small numbers of calves are studied. (Am J Vet Res 1998;59: 1108-1112)
Expression and bioactivity of recombinant canine erythropoietin
Authors: MacLeod James N. , Tetreault Jonathan W. , Lorschy Kellie A. S. , Gu Da Nian
Published: January 2024

Objective

To produce recombinant canine erythropoietin (rcEPO) and compare its biological activity with that of recombinant human EPO (rhEPO).

Animals

C57BL/6J mice.

Procedure

The gene encoding cEPO was isolated from a genomic library and subcloned into an eucaryotic expression vector. Production of rcEPO was achieved by stable transfection of the expression construct into Chinese hamster ovary cells. Biological activity was evaluated in vitro by analyzing the mitogenic activity of rcEPO on murine erythroid progenitor cells. In vivo bioactivity was assessed in mice by measuring the ability of rcEPO to increase blood reticulocyte counts.

Results

Size and glycosylation of rcEPO expressed in Chinese hamster ovary cells were similar to values for commercial rhEPO. Canine and human EPO stimulated proliferation of murine erythroid progenitor cells in vitro and murine reticulocytosis in vivo in a dosedependent manner.

Conclusions

Comparable biological activity was observed for rcEPO and rhEPO in the 2 murine-based assay systems studied. By avoiding interspecies variation in protein structure and the resulting potential for immunogenicity, rcEPO should represent a better option than rhEPO for treatment of dogs with erythropoietin-dependent anemia.

Clinical Relevance

Therapeutic use of rhEPO in companion animals is limited by its immunogenicity and the resulting potential to induce pure red cell aplasia. Development and availability of species-specific EPO preparations should avoid this problem. (Am J Vet Res 1998;59:1144-1148)
Anti-inflammatory effects of topically applied dimethyl sulfoxide gel on endotoxin-induced synovitis in horses
Authors: Smith Gregory , Bertone Alicia L. , Kaeding Christopher , Simmons Emily J. , Apostoles Steven
Published: January 2024

Objective

To evaluate the effect of topically applied dimethylsulfoxide (DMSO) on lipopolysaccharide (LPS)-induced synovitis in the mid-carpal joint.

Animals

6 sound, healthy, adult horses (12 carpi).

Procedure

In a double-blinded, crossover, paired study with a 1-week washout period, mid-carpal joints were allocated to group 1 (DMSO, n = 6) or group 2 (control, n = 6). Each joint was injected with 1.3 ml (0.0125 ng/dl) of LPS to induce synovitis. For group-1 joints, DMSO gel (15 g; 90%) was applied after injection of LPS and at 12-hour intervals for 60 hours. Joints of group 2 received LPS, but not DMSO gel. All horses were evaluated by serial lameness examinations and synovial fluid analyses (total and differential WBC count and total protein concentration) at 12- hour intervals for 60 hours after LPS injection. Plasma and synovial fluid were obtained at baseline and 36 hours to document presence of DMSO.

Results

Mean WBC concentration was significantly (P < 0.05) lower in group-1, compared with group-2 joints, at 24 hours and had a trend to be lower at 36 hours. Mean total neutrophil count was significantly lower in group-1, compared with group-2 joints at 24 hours. In group-1 joints, DMSO was detected by use of gas chromatography in the synovial fluid of 5 of 6 joints and in plasma from 1 of 6 horses.

Conclusion

Topically applied DMSO penetrated into synovial fluid in sufficient quantities to be detected and to decrease joint inflammation. (Am J Vet Res 1998;59:1149-1152)
Detection of Haemobartonella felis in cats with experimentally induced acute and chronic infections, using a polymerase chain reaction assay
Authors: Berent Linda M. , Messick Joanne B. , Cooper Sandra K.
Published: January 2024

Objective

To develop a test for detection of Haemobartonella felis, using a polymerase chain reaction (PCR) assay.

Animals

4 adult cats seronegative for FeLV and feline immunodeficiency virus.

Procedure

Cats were infected with H felis by IV administration of 1 ml of blood obtained from an infected cat. Rectal temperature, PCV, and microscopic examination of blood smears for organisms were monitored daily. At peak of infection, doxycycline treatment was initiated for 21 days. Blood samples were collected at weekly intervals. Six months after treatment, 2 cats were given methylprednisolone (14 mg/kg of body weight, IM). Daily blood samples were collected for CBC, detection of organisms, and PCR evaluation. On the basis of the 16S rRNA gene sequence of H felis,specific PCR primers were created for a 393-basepair internal fragment.

Results

The 393-basepair product was consistently amplified from blood samples obtained during peak parasitemia but not during the last week of or immediately after completion of doxycycline treatment. After treatment, PCV returned to the reference range, and organisms were not observed in blood samples; however, the PCR product could be consistently amplified. After administration of methylprednisolone, organisms were only rarely observed in blood smears but were consistently detected by PCR analysis.

Clinical Relevance

Using PCR analysis, it was possible to detect H felisin blood samples obtained from cats during peak parasitemia, during most of the carrier phase, and after challenge with immunosuppressive drugs. During and immediately after antibiotic treatment, this test may fail to detect the organisms. (Am J Vet Res1998;59:1215–1220)
Effects of acepromazine and butorphanol on positive-contrast upper gastrointestinal tract examination in dogs
Authors: Scrivani Peter V. , Bednarski Richard M. , Myer C. Wendy
Published: January 2024

Objective

To determine whether acepromazine (ACE) and butorphanol (BUT) combination can be used for restraint of dogs during positive-contrast upper gastrointestinal tract (UGIT) examination.

Animals

6 healthy dogs.

Procedure

In a randomized crossover design study, weekly UGIT examinations were performed on each dog for 5 weeks after administration of normal saline solution (0.5 ml), xylazine (1.0 mg/kg of body weight), or a combination of ACE (0.1 mg/kg) and 1 of 3 doses of BUT (0.05, 0.2, 1.0 mg/kg). Gastrointestinal tract emptying time, GI motility, pulse, respiratory rate, and quality of restraint were assessed.

Results

Total gastric emptying time was significantly prolonged by use of an ACE and BUT (0.05 mg/kg) combination. Xylazine and higher dosages of BUT significantly prolonged gastric and intestinal emptying times. All anesthetic protocols significantly decreased motility and facilitated nonmanual restraint. Xylazine and BUT (1.0 mg/kg) significantly decreased pulse and respiratory rate.

Conclusion

The ACE and BUT combination prolonged GI tract emptying times, decreased GI motility, and facilitated nonmanual restraint for duration of the examination. Although GI motility was decreased and total gastric emptying time was prolonged, administration of ACE (0.1 mg/kg) plus BUT (0.05 mg/kg) allowed morphologic examination of the GI tract within 5 hours. Xylazine prolonged GI tract emptying, decreased GI motility, and provided good to excellent initial restraint.

Clinical Relevance

The ACE and BUT combination prohibits functional examination of the GI tract; however, morphologic examination is possible when low dosages of BUT (0.05 mg/kg) are used. (Am J Vet Res 1998;59:1227–1233)
Effects of buprenorphine on cardiovascular and pulmonary function in clinically normal horses and horses with chronic obstructive pulmonary disease
Authors: Szöke Mihàly O. , Blais Diane , Cuvelliez Sophie G. , Lavoie Jean-Pierre
Published: January 2024

Objectives

To evaluate the cardiovascular and respiratory effects of buprenorphine administered intravenously in clinically normal horses and horses with chronic obstructive pulmonary disease (COPD).

Animals

5 clinically normal horses and 5 horses with COPD that were in partial clinical remission (period A) or were having an acute attack of airway obstruction (period B).

Procedures

Pulmonary function testing, arterial blood gas analysis, and arterial blood pressure measurements were performed before and after a single intravenous bolus of buprenorphine (3 μg/kg of body weight). Respiratory rate (f), tidal volume (VT), expiratory-to-inspiratory time ratio (TE/TI), minute expiratory ventilation (VE), maximal change in transpulmonary pressure (ΔPL), dynamic compliance (Cdyn), and pulmonary resistance (RL) were calculated with a pulmonary function computer. Heart rate (HR) and systolic (SABP), diastolic (DABP), and mean arterial blood pressures (MABP) were measured.

Results

At baseline, COPD horses in period A had decreased Cdyn and increased f, VE, PL, and HR, whereas COPD horses in period B had decreased TE/TI and Cdyn, arterial blood pH, and Po2, and increased f, vE, ΔPL, and RL, compared with clinically normal horses. After drug administration, SABP, DABP, and MABP increased in all horses, f and VE increased in clinically normal horses, and Pao2 decreased within 60 minutes in horses with COPD.

Conclusion and Clinical Relevance

Buprenorphine can induce excitement in unsedated horses or horses that do not have signs of pain, but does not seem to induce severe respiratory depression or adverse cardiovascular effects in clinically normal horses or those with COPD. (Am J Vet Res 1998;59:1287–1291)
Effect of radiographic positioning on interpretation of cubital joint congruity in dogs
Authors: Murphy Scott T. , Lewis Daniel D. , Shiroma Jonathan T. , Neuwirth Lisa A. , Parker Robert B. , Kubilis Paul S.
Published: January 2024

Objective

To ascertain effects of x-ray beam centering and limb position on apparent congruity of a normal cubital joint (elbow).

Animals

6 skeletally mature male Treeing Walker Coonhounds without physical, radiographic, or gross evidence of elbow abnormalities.

Procedure

Relative movement among humerus, radius, and ulna and measured joint space width on mediolateral and craniocaudal radiographic views was compared, using various x-ray beam centering and limb positions.

Results

Highest agreement and greatest certainty on subjective determination of congruity was for the flexed 90° mediolateral radiographic view with the x-ray beam centered on the elbow. Distortion artifact of the proximal ulnar measurements was significant when the x-ray beam was centered on the midpoint of the radius. On the mediolateral view, the humeroradial joint space became significantly wide when the elbow was flexed. On the craniocaudal view, maximal humeroradial joint space width was obtained when the x-ray beam bisected the angle of the joint or was angled +30° toward the humerus.

Conclusions

Artifact distortion of joint width affected objective and subjective assessment of elbow congruity when the limb was placed in extreme flexion or extension or when the x-ray beam was not centered over the area of interest. Optimal visualization of the humeroradial joint space on the craniocaudal view was achieved when the x-ray beam bisected the angle of the elbow or was slightly angled toward the humerus.

Clinical Relevance

Elbow congruity was best assessed on the flexed 90° lateral radiographic view with the x-ray beam centered on the joint. (Am J Vet Res 1998;59:1351–1357)
Normal variation in, and effect of 2% pilocarpine on, intraocular pressure and pupil size in female horses
Authors: van der Woerdt Alexandra , Gilger Brian C. , Wilkie David A. , Strauch Stephen M. , Orczeck Shawn M.
Published: January 2024

Objective

To determine normal variation in, and effect of 2% pilocarpine hydrochloride on, intraocular pressure (IOP) and pupil size in female horses during a specified period.

Animals

10 female horses with normotensive eyes.

Procedure

IOP and horizontal and vertical pupil size were measured on a single day between 8 am and 8 pm at hours 0, 0.5, 1, 2, 4, 6, 8, 10, and 12. Measurements were repeated after single-dose application of 2% pilocarpine to both eyes. IOP and pupil size were measured at 8 am and noon in a 5-day experiment of twice-daily application of 2% pilocarpine.

Results

Variation in IOP and pupil size was not significant between 8 am and 8 pm. Change in IOP or pupil size after a single dose of 2% pilocarpine also was not significant. In the multiple-dose experiment, the IOP at noon on the fifth day was significantly higher than the IOP in the morning on the first and second days. The IOP in the morning on the fifth day was significantly higher than the IOP in the morning and at noon on the first and second days. The IOP at noon on the fourth day was significantly higher than the morning IOP on the first and second days and at noon on the first day. The decrease in vertical pupil size was significant.

Conclusions

Between 8 am and 8 pm, variation in IOP and pupil size in normotensive eyes of horses is not significant. Two percent pilocarpine does not significantly change IOP between 8 am and 8 pm in clinically normal horses after a single dose or multiple twice-daily applications. After multiple twice-daily applications, a trend toward an increase in IOP was seen, and the decrease in vertical pupil size was significant. (Am J Vet Res 1998;59:1459–1462)
Effects of dopamine, dobutamine, dopexamine, phenylephrine, and saline solution on intramuscular blood flow and other cardiopulmonary variables in halothane-anesthetized ponies
Authors: Lee Y-H. L. , Clarke K. W. , Alibhai H. I. K. , Song D.
Published: January 2024

Objective

To evaluate the effect on intramuscular blood flow (IMBF) and hemodynamic variables of 4 antihypotensive agents given during anesthesia.

Animals

8 ponies.

Procedure

Halothane-anesthetized ponies (n = 6) positioned in lateral recumbency received, on separate occasions, infusions of each of the following 4 agents in serially increasing dosages or saline solution: phenylephrine hydrochloride (0.25, 0.5, 1, and 2 μg/kg of body weight), dopamine (2.5, 5, 10, and 20 μg/kg), dobutamine (1, 2.5, 5, and 10 μg/kg), and dopexamine (0.5, 1, 5, and 10 μg/kg). Changes in IMBF (by laser-Doppler flowmetry) in nondependent and dependent triceps brachii muscles and cardiopulmonary variables were measured.

Results

Phenylephrine at all dosages failed to improve IMBF or cardiac index (CI), but increased mean arterial pressure (MAP) and systemic vascular resistance (SVR); 2 ponies had forelimb lameness on recovery. Dopamine (10 μg/kg/min) increased Cl, MAP, and IMBF in the dependant muscle. A higher dose (20 μg/kg/min) caused cardiac arrhythmias and muscular tremor. Dobutamine increased Cl, MAP, and IMBF of both forelimbs, effects being significant for 2.5 μg/kg/min, with further improvement as the dosage increased. In 2 ponies, 10 μg of dobutamine/kg/min caused cardiac arrhythmias. Dopexamine (1 and 5 μg/kg/min) increased Cl, MAP, and IMBF in the nondependent muscle, and 10 μg/kg/min caused muscular tremor, sweating, and arrhythmias. SVR was reduced after infusion of dopamine, dobutamine, or dopexamine.

Conclusion

During anesthesia of equids, an increase in CI and MAP is necessary to improve IMBF in the dependant forelimb.

Clinical Relevance

Of the agents investigated, dobutamine proved the most consistent in improving IMBF. (Am J Vet Res 1998;59:1463–1472)
Hepatic blood flow in horses during the recuperative period from maximal exercise
Authors: Dyke Timothy M. , Hubbell John A. E. , Sams Richard A. , Hinchcliff Kenneth W.
Published: January 2024

Objective

To determine effects of walking or standing on hepatic blood flow of horses after brief, intense exercise.

Animals

6 adult Thoroughbreds (4 mares, 2 geldings).

Procedure

Horses were preconditioned on a treadmill to establish uniform level of fitness. Once fit, treadmill speed causing each horse to exercise at 120% of maximal oxygen consumption was determined and used in simulated races at 14-day intervals. In a three-way crossover study, horses were exercised at a speed inducing 120% of maximal oxygen consumption until fatigued or for a maximum of 2 minutes. Three interventions were studied: resting on the treadmill (REST), exercised then standing on the treadmill for 30 minutes (MS), and exercised then walking at 2 m/s for 30 minutes (MW). At 60 seconds after completion of exercise, bromsulphalein (BSP) was infused IV, and blood samples were collected every 2 minutes for 30 minutes for analysis of BSP concentration. Hematocrit and plasma total solids concentration were measured. Pharmacokinetic parameters were derived, using nonlinear regression, and were compared, using Friedman’s repeated measures analysis on ranks.

Results

Plasma BSP concentration was higher after exercise. Median hepatic blood flow (BSP clearance) decreased significantly from 23.8 (REST) to 20.7 (MS) and 18.7 (MW) ml/min/kg. Median steady-state volume of distribution of BSP decreased from 47.6 (REST) to 42.7 (MW) and 40.2 (MS) ml/kg. Differences among trials were not significant when horses walked or stood after exercise.

Conclusions

Hepatic blood flow and pharmacokinetics of BSP are markedly altered immediately after exercise. Limiting movement of horses during this period did not affect hepatic blood flow. (Am J Vet Res 1998;59:1476–1480)
Cardiopulmonary effects of bilateral hemithorax ventilation and diagnostic thoracoscopy in dogs
Authors: Faunt Karen K. , Cohn Leah A. , Jones Brent D. , Dodam John R.
Published: January 2024

Objective

To describe alterations in respiratory and cardiovascular variables during diagnostic thoracoscopy, using bilateral hemithorax ventilation with sustained pneumothorax.

Animals

7 adult dogs.

Procedure

Each dog was anesthetized and instrumented for 2 episodes of cardiopulmonary monitoring that were performed at an interval of more than 14 days. The first anesthetic episode served as a control procedure for the thoracoscopy treatment performed during the second anesthetic episode. Multiple cardiopulmonary variables were evaluated by comparing changes from baseline values within treatments and between treatments.

Results

Arterial oxygen tension decreased significantly from baseline values during thoracoscopy but was unchanged during sham treatment. Arterial carbon dioxide tension, clinical shunt fraction, and systemic mean arterial pressure increased during thoracoscopy. In contrast, these variables were unaffected by the sham treatment. Heart rate and cardiac index increased during sham and thoracoscopy treatments; however, the increase was significantly greater during thoracoscopy. Total peripheral vascular resistance significantly decreased from baseline values for both treatments, but the decrease was greater during thoracoscopy. Significant changes were not observed for oxyhemoglobin saturation or pulmonary vascular resistance during either treatment. Dogs recovered without major clinical complications.

Conclusions

Significant changes were found for several cardiopulmonary variables during bilateral hemithorax ventilation with sustained pneumothorax for diagnostic thoracoscopy of clinically normal dogs.

Clinical Relevance

Diagnostic thoracoscopy with bilateral hemithorax ventilation and sustained pneumothorax is well tolerated in clinically normal dogs and may provide a diagnostic modality enabling intrathoracic procedures with less morbidity than thoracotomy for dogs with intrathoracic disease. (Am J Vet Res 1998;59:1494–1498)