bluuebunny/crossref_metadata_2025 huggingface dataset:
Myoelectric activity of the cecum and proximal loop of the ascending colon in cows after spontaneous cecal dilatation/dislocation
Authors: Stocker Susi , Steiner Adrian , Geiser Susi , Kündig Hans
Published: January 2024

Objective

To analyze myoelectric activity of the cecum and proximal loop of the ascending colon (PLAC) in cows after spontaneous cecal dilatation/dislocation (CDD) and compare it with that in healthy cows after surgical evacuation of the cecum.

Animals

12 cows with spontaneous CDD and 6 healthy cows (group C). Cows with spontaneous CDD were retrospectively assigned to 2 groups: delayed recovery from surgery or recurrence (group A; n = 3), and normal recovery (group B; n = 9).

Procedure

After surgical evacuation of the cecum, 8 pairs of bipolar, retrievable electrodes were implanted in the ileum, cecum, and PLAC. Cows were evaluated daily from postoperative day 1 to 7, using routine clinical methods and computer-based analysis of myoelectric activity of the cecum and PLAC. Parameters of myoelectric activity included rate of spike bursts, duration of individual spike bursts, duration of overall spike burst activity per electrode, rate of propagated spike burst sequences, and ratio of orally propagated spike burst sequences.

Results

Rate of spike bursts, duration of cecocolic spike burst activity, and ratio of orally to aborally propagated spike burst sequences did not vary among groups during the 7-day recording period. However, cows with delayed recovery had a typical, uniform pattern of myoelectric activity of the cecum and PLAC at days 1 and 2 after surgery that consisted of repeated, propagated spike burst sequences, made up of spike bursts of significantly (P < 0.05) increased duration at postsurgical day 1 and substantially prolonged duration at postsurgical day 2, interrupted by periods of little or no activity.

Conclusion

Delayed recovery and recurrence of CDD in cows after spontaneous CDD is not caused by hypomotility of the cecum and PLAC.

Clinical Relevance

Postoperative treatment, intended to reduce recurrence of CDD or delayed recovery after surgical evacuation of the cecum, should address propagation of digesta in the spiral colon. (Am J Vet Res 1997;58:961–968)
Developmental variation in lumbosacropelvic anatomy of Thoroughbred racehorses
Authors: Haussler Kevin K. , Stover Susan M. , Willits Neil H.
Published: January 2024

Objective

To describe the incidence and types of gross osseous developmental variations and ages of physeal closure in the caudal portion of the thoracic and lumbosacral spine and the pelvis in a sample of Thoroughbred racehorses.

Animals

Thoroughbred racehorses (n = 36) that died or were euthanatized at California racetracks between October 1993 and July 1994.

Procedure

Lumbosacropelvic specimens were collected, and all soft tissues were removed. The osseous specimens were visually examined.

Results

Only 22 (61 %) specimens had the expected number of 6 lumbar and 5 sacral vertebrae. Eight (22%) specimens had thoracolumbar transitional vertebrae, and 13 (36%) had sacrocaudal transitional vertebrae. Articular process asymmetries were present at 1 or more vertebral segments in 30 (83%) specimens. Intertransverse joints (2 to 4 pairs/specimen) were bilaterally distributed in the caudal portion of the lumbar spine and the lumbosacral joint in 31 (86%) specimens. Five (14%) specimens had asymmetric distribution of the intertransverse joints. Intertransverse joint ankylosis was found in 10 (28%) specimens. Lumbosacral vertebral body physeal closure occurred between 4.9 and 6.7 years of age; pelvic physeal closure occurred between 5.2 and 5.8 years of age. Iliac crest and ischial arch epiphyseal formation was evaluated, using a grading system, and fusion to the underlying bone occurred at 7.2 years and 5.4 years of age, respectively.

Conclusions

Numerous vertebral anatomic variations were commonly found in a sample of Thoroughbred racehorses.

Clinical Relevance

Normal anatomic variations and ages of skeletal maturity need to be considered in clinical evaluation of the equine spine and pelvis for differentiation from pathologic findings. (Am J Vet Res 1997;58:1083–1091)
Effects of various feeding regimens on the energy balance of equine neonates
Authors: Ousey Jennifer C. , Prandi Simona , Zimmer Jutta , Holdstock Nicola , Rossdale Peter D.
Published: January 2024

Objective

To determine the effect of diet on energy intake, loss, and metabolism in foals 2 to 7 days old.

Animals

14 pony foals.

Procedure

Group-A foals suckled their dams, group-B foals were fed milk replacer, and group-C foals were fed by total parenteral nutrition (TPN). Energy balance studies were performed over 8-hour periods on postpartum days 2, 4, and 7.

Results

Mean gross energy (GE) intake of group-A foals increased between days 2 and 7. Approximately 3% of GE was excreted in urine and feces, and energy expenditure remained constant. These foals were in positive energy balance, and mean body weight increased. From day 4 onward, group-B foals consumed more energy than did group-A foals because the milk replacer had a higher energy content than did mares’ milk. Mean energy loss in group-B foals was 14% of GE on day 2, but this value decreased subsequently. Energy expenditure in group-B foals was less than that in group-A foals, and energy balance was positive. Group-C foals had the lowest energy intake and expenditure; energy balance was negative on postpartum day 2. These foals also had gastrointestinal tract problems.

Conclusions

Mares’ milk is highly digestible and is correlated with positive energy balance in neonatal foals. Milk replacer initially is less digestible than mares’ milk. In this study, TPN was associated with negative energy balance.

Clinical Relevance

The data indicate the advantages of enteral feeding with mares’ milk and highlight the clinical and technical difficulties associated with TPN. (Am J Vet Res 1997;58:1243–1251)
Effect of alfentanil on the minimum alveolar concentration of isoflurane in cats
Authors: Ilkiw Jan E. , Pascoe Peter J. , Fisher Linda D.
Published: January 2024

Objective

To evaluate effect of incremental doses of alfentanil on isoflurane minimum alveolar concentration (MAC) in cats to determine whether alfentanil reduces isoflurane MAC and, if so, maximal isoflurane MAC reduction.

Animals

6 healthy spayed female cats.

Procedure

Cats were anesthetized with isoflurane and instrumented to allow collection of arterial blood for measurement of gas tensions, pH, and plasma alfentanil concentration and to measure arterial blood pressure. Isoflurane MAC was determined in triplicate, and alfentanil was administered IV, using a computer-driven syringe pump to achieve estimated plasma alfentanil concentrations of 50, 100, 250, 500, 750, and 1,000 ng/ml; isoflurane MAC was determined at each alfentanil concentration. Cats were allowed to recover, and the process was graded as poor, good, or excellent.

Results

Alfentanil had a significant dose effect on isoflurane MAC reduction. Significant regression was found for normalized isoflurane MAC versus estimated plasma alfentanil concentration. A quadratic term was necessary to fit the model and, using this curve, MAC reduction (35.0 ± 6.6%) was estimated to be maximal at a plasma alfentanil concentration of 500 ng/ml. Significant differences were evident in rectal temperature, bicarbonate concentration, base deficit, arterial carbon dioxide and oxygen tensions, and arterial pH between isoflurane alone and some plasma alfentanil concentration and the corresponding reduction in isoflurane concentration.

Conclusions

Infusion of alfentanil resulted in maximal MAC reduction midway between that reported for horses and dogs. At such plasma alfentanil concentration, adverse effects were minimal, but included increase in rectal temperature, metabolic acidosis, and decrease in Pao2. Provided cats were not handled during the recovery period, recovery was smooth and quiet.

Clinical Relevance

Infusion of alfentanil decreases the need for potent inhalant anesthetics in cats and could potentially be a clinically useful anesthetic regimen in sick cats. (Am J Vet Res 1997;58:1274–1279)
Mitogenic effects of epidermal growth factor and platelet-derived growth factor on canine and equine mesangial cells in vitro
Authors: Ennulat Daniela , Brown Cathy A. , Brown Scott A.
Published: January 2024

Objective

To evaluate the effects of epidermal growth factor (EGF) and platelet-derived growth factor (PDGF) on canine and equine mesangial cell (MC) proliferation in vitro.

Sample Population

Third-through eighth-passage canine and equine MC were obtained from explant outgrowth after differential sieving of glomeruli isolated from the kidneys of clinically normal dogs and horses.

Procedure

Mitogenic effects of serum, insulin, EGF, and PDGF were evaluated in MC by induction of DNA synthesis, measured as stimulation of [3H]thymidine incorporation and increase in cell numbers.

Results

Epidermal growth factor was a potent mitogen in canine and equine MC, stimulating dose-dependent increases in [3H]thymidine incorporation and moderate increase in cell numbers. Although PDGF alone did not significantly stimulate [3H]thymidine incorporation in canine MC, PDGF was synergistic with EGF in stimulation of [3H]thymidine incorporation in canine and equine MC, and PDGF significantly stimulated [3H]thymidine incorporation in equine MC.

Conclusions

Both EGF and PDGF are important mediators of canine and equine MC proliferation.

Clinical Relevance

Our results are consistent with the hypothesis that growth factors have a role in the progression of glomerular disease in dogs and horses. These findings could prove to be of diagnostic, prognostic, and therapeutic value in the management of spontaneous renal disease in these species. (Am J Vet Res 1997;58:1308–1313)
Differences between longitudinal and circular smooth muscle in β-adrenergic control of motility of isolated equine ileum
Authors: Belloli Chiara , Re Giovanni , Arioli Francesco , Badino Paola , Carcano Roberta , Odore Rosangela , Girardi Carlo , Beretta Carlo
Published: January 2024

Objective

To identify β-adrenoceptor subtypes involved in motility inhibition of circular and longitudinal smooth muscle layers of equine ileum.

Sample Population

Isolated strips of equine ileum circular smooth muscle and membrane preparations from circular and longitudinal muscle layers.

Procedure

Functional assays of circular muscle preparations and radioligand binding assays and measurements of cAMP production in smooth muscle membranes from circular and longitudinal layers.

Results

Selective β-adrenergic agonists exerted inhibitory effects on circular muscle preparations. Binding studies of cell membranes indicated that the density and distribution of 3 β-adrenoceptor subtypes did not differ between longitudinal and circular muscle layers. Measurement of cAMP production in membrane preparations of longitudinal and circular muscle after selective β-stimulation confirmed presence of the 3 adenylate cyclase-coupled β-adrenoceptor subtypes; however, preparations from the 2 layers had differing cAMP production efficacy.

Conclusions

The data may partly explain the differing functional responses between circular and longitudinal muscle preparations.

Clinical Relevance

Findings support the important role of β-atypical adrenoceptors in the inhibitory regulation of equine ileum motility. (Am J Vet Res 1997;58:1422–1426)
Pharmacokinetics of cisapride in horses after intravenous and rectal administration
Authors: Cook Gabriel , Papich Mark G. , Roberts Malcolm C. , Bowman Karl F.
Published: January 2024

Objectives

To determine the IV pharmacokinetics of cisapride and measure systemic absorption after rectal administration.

Animals

5 healthy adult mares (380 to 610 kg).

Procedure

Cisapride was administered, IV, at a dosage of 0.1 mg/kg of body weight. In the same horses, after a 1-week washout period, cisapride was administered rectally at a dosage of 1 mg/kg by mixing crushed tablets with propylene glycol and administering the mixture into the rectum. After each drug administration, a series of blood samples were collected. Plasma was obtained and analyzed by high-performance liquid chromatography to determine cisapride concentration profiles after each drug administration.

Results

After IV administration, peak plasma concentration was 221.4 ng/ml and harmonic mean half-life was 1.9 hours. Rectal absorption of cisapride was negligible. Cisapride was detected in plasma from only 3 of 5 horses for which mean systemic availability was 1.23%. Mean maximal plasma concentration after rectal administration of cisapride was 13.5 ng/ml.

Conclusion and Clinical Relevance

After IV administration of cisapride, plasma concentration is high for approximately 2 hours. Cisapride mixed with propylene glycol and administered rectally at a dosage of 1 mg/kg is poorly and incompletely absorbed. Thus, cisapride is not clinically useful for rectal administration in horses. (Am J Vet Res 1997;58:1427–1430)
Insulin-like growth factor I peptide elution profiles from fibrin polymers determined by use of high-performance liquid chromatography
Authors: Foley Robert L. , Nixon Alan J.
Published: January 2024

Objective

To develop a high-performance liquid chromatography (HPLC) assay for insulin-like growth factor I (IGF-I) and to use it to quantify elution of IGF-I from polymerized fibrin in an in vitro system.

Sample Population

Equine fibrinogen and calcium-activated bovine thrombin were used to form fibrin containing human recombinant IGF-I.

Procedure

Multiple fibrin disks were formed from polymerized fibrinogen and thrombin; 6 disks were loaded with 25 μg of recombinant human IGF-I at the time of polymerization, and 4 remained as unladen controls. The resultant clots were incubated at 37 C and 90% humidity for 22 days. Phosphate-buffered saline solution in each well was replaced daily, and IGF-I content was assayed by HPLC. Solid-phase separation was used to assay free IGF-I peptide peaks. A scan was done to determine optimal wavelength for IGF-I absorbance. Commercially pure IGF-I was used to construct a standard curve, and the IGF-I content of medium removed from all 10 wells each day was assayed.

Results

Pure unbound IGF-I eluted from the fibrin polymers for 22 days; initial rapid daily release of 1.6 to 1.7 μg of IGF/ml of medium changed after day 3 to commence an asymptotic decrease to 110 ng of IGF/ml by day 22. The fibrin disks had dissolved by day 22, and the experiment was terminated. Control disks did not have detectable IGF-I content at any time. Limit of the HPLC assay was 25 ng of IGF-l/ml. Retention time for nonprotein-bound IGF-I was 10.3 ± 0.15 minutes.

Conclusion

IGF-I (25 μg) can be added to polymerized fibrin and eluted as free ligand over a 22-day period of culture at 37 C. Release of IGF-I was initially independent of fibrin dissolution, but later appeared to follow a pattern consistent with fibrin degradation.

Clinical Relevance

IGF-I can be incorporated as a depot form in polymerized fibrin and is released over time in sufficient concentration to effectively stimulate articular chondrocyte metabolic activity. (Am J Vet Res 1997;58:1431–1435)
Comparison of alveolar ventilation, oxygenation, pressure support, and respiratory system resistance in response to noninvasive versus conventional mechanical ventilation in foals
Authors: Hoffman Andrew M. , Kupcinskas Rachel L. , Paradis Mary Rose
Published: January 2024

Objective

To compare the efficacy of positive pressure ventilation applied through a mask versus an endotracheal tube, using anesthetized/paralyzed foals as a model for foals with hypoventilation.

Animals

Six 1-month-old foals.

Procedure

A crossover design was used to compare the physiologic response of foals to 2 ventilatory techniques, noninvasive mask mechanical ventilation (NIMV) versus endotracheal mechanical ventilation (ETMV), during a single period of anesthesia and paralysis. Arterial pH, Pao2, Paco2, oxygen saturation, end-tidal CO2 tension, airway pressures, total respiratory system resistance, resistance across the upper airways (proximal to the midtracheal region), and pos-itive end-expiratory pressures (PEEP) were measured. Only tidal volume (VT; 10, 12.5, and 15 ml/kg of body weight) or PEEP (7 cm of H2O) varied.

Results

Compared with ETMV, use of NIMV at equivalent VT resulted in Paco2 and pH values that were significantly higher, but Pao2 was only slightly lower. Between the 2 methods, peak airway pressure was similar, but peak expiratory flow was significantly lower and total respiratory resistance higher at each VT for NIMV. Delivery of PEEP (7 cm of H2O) was slightly better for ETMV (7.1 ± 1.3 cm of H2O) than for NIMV (5.6 ± 0.6 cm of H2O).

Conclusion

These data suggest that use of NIMV induces similar physiologic effects as ETMV, but the nasal cavities and mask contribute greater dead space, manifesting in hypercapnia. Increasing the VT used on a per kilogram of body wieght basis, or the use of pressure-cycled ventilation might reduce hypercapnia during NIMV.

Clinical Relevance

Use of NIMV might be applicable in selected foals, such as those with hypoventilation and minimal changes in lung compliance, during weaning from endotracheal mechanical ventilation, or for short-term ventilation in weak foals. (Am J Vet Res 1997;58:1463–1467)
Clinical effects of porcine reproductive and respiratory syndrome virus on pigs during the early postnatal interval
Authors: Mengeling William L. , Lager Kelly M. , Vorwald Ann C.
Published: January 2024

Objective

To determine the effect of congenital and early postnatal infection of pigs with porcine reproductive and respiratory syndrome virus (PRRSV) on postnatal survival and growth.

Animals

20 pregnant gilts and their pigs and fetuses.

Procedure

16 pregnant gilts (principals) comprising 4 groups (4 gilts/group) were exposed oronasally to 4 strains of PRRSV (a vaccine strain, and 3 field strains) at or about day 90 of gestation. Four pregnant gilts (controls) were kept under similar conditions, except for exposure to PRRSV. Samples collected from pigs before ingestion of colostrum and samples and specimens collected from pigs at selected times thereafter were tested for PRRSV and homologous antibody. Pigs were observed for clinical signs and were weighed at birth and at weekly intervals until they were euthanatized and necropsied at about 3 weeks of age.

Results

At least some members of all litters of principal gilts were infected congenitally. Most noninfected, liveborn littermates became infected within the first week of life. Infection of pigs with field strains did, and infection of pigs with the vaccine strain did not, adversely affect postnatal survival and growth rate. All infected pigs had generalized lymph node enlargement.

Conclusion

Exposure of pregnant gilts to either attenuated (vaccine) or virulent (field) strains of PRRSV can result in congenital infection. Vaccine as well as field strains can be transmitted postnatally from infected to noninfected littermates. Pigs infected with field strains have a poorer rate of survival and growth than do noninfected pigs.

Clinical Relevance

Because attenuated (vaccine) PRRSV can cause congenital infection and be transmitted postnatally from congenitally infected to immune-naive pigs, the use of attenuated virus during gestation is, at best, questionable. (Am J Vet Res 1998;59:52–55)
Effects of training on collagen fibril populations in the suspensory ligament and deep digital flexor tendon of young Thoroughbreds
Authors: Patterson-Kane J. C. , Firth E. C. , Parry D. A. D. , Wilson A. M. , Goodship A. E.
Published: January 2024

Objective

To determine the effect of a specific galloping exercise regimen on collagen fibril mass-average diameters (MAD) in the deep digital flexor tendon (DDFT) and suspensory ligament (SL) of young Thoroughbreds.

Animals

12 Thoroughbred fillies, 21 ± 1 (mean ± SD) months old.

Procedure

6 horses underwent a specific 18-month treadmill training program involving galloping exercise. The remaining 6 horses served as controls, undertaking low-volume walking exercise over the same period. Sections were excised from the midpoint of the DDFT and SL, and small strips were dissected from central and peripheral locations for each structure. Fibril diameters were measured from micrographs of transverse ultrathin sections, using a computerized image analysis program. An MAD value was calculated for the central and peripheral regions of the DDFT and SL for each horse. Values for both regions were compared between exercised and control horses.

Results

The MAD did not change significantly with exercise for either the DDFT or the SL.

Conclusion

Loading of the DDFT as a result of this exercise regimen was not sufficient to stimulate collagen fibril hypertrophy, in keeping with current data that indicate this tendon, compared with the SL and superficial digital flexor tendon (SDFT), is subjected to low loads. Microtrauma, in terms of reduction in fibril MAD, may have occurred in the SL at a site different from that sampled. Another possibility is that, between the trot and the gallop, loading of the SL does not increase to the same extent as that of the SDFT. (Am J Vet Res 1998;59:64–68)
Effects of hypochlorous acid and ascorbic acid on conductance, permeability, and structure of equine colonic mucosa in vitro
Authors: Inoue Olivia J. , Freeman David E. , Wallig Matthew
Published: January 2024

Objectives

To study effects of hypochlorous acid (HOCI) on equine colonic mucosa in vitro, and determine whether addition of ascorbic acid protects against the effects.

Animals

6 healthy horses and ponies.

Procedure

Short-circuit current was measured in mucosa mounted in Ussing chambers. Incubation conditions were: control (no additions); 5 mM HOCI; 1 mM HOCI; same and 5 mM ascorbic acid; 3 mM HOCI; 3 mM HOCI and 5 mM ascorbic acid; 7 mM HOCI; and 7 mM HOCI plus 5 mM ascorbic acid. Permeability was measured with [3H]mannitol and, at the conclusion of each experiment, tissues were examined microscopically to assess the effects of HOCI and ascorbic acid, alone or in combination.

Results

Short circuit current and conductance increased transiently in response to 1 mM HOCI. Tissues had mild surface epithelial damage, as evident by swelling and separation of isolated cells. These changes were abolished when tissues were coincubated with 5 mM ascorbic acid and 1 mM HOCI. At 3 and 7 mM concentrations, HOCI caused marked increase in tissue conductance, short circuit current, and permeability to mannitol; these changes were associated with histologic damage. Again, coincubation with 5 mM ascorbic acid protected against these changes. Additional studies indicated that the effects of HOCI and the protective effects of ascorbic acid were not mediated through changes in pH.

Conclusions

HOCI in low concentrations is capable of increasing the short-circuit current in equine colon, possibly by increasing secretions; however, higher concentrations can cause tissue damage. The addition of 5 mM ascorbic acid blocks these changes.

Clinical Relevance

The concentration of HOCI produced by activated neutrophils could damage equine colonic mucosa and potentially contribute to or cause reperfusion injury. The ability of ascorbic acid to ameliorate this injury in an in vitro setting offers a potential method for pharmacologic evaluation of this injury and for treatment. (Am J Vet Res 1998;59:82–87)
Cell trafficking, mediator release, and articular metabolism in acute inflammation of innervated or denervated isolated equine joints
Authors: Hardy Joanne , Bertone Alicia L. , Weisbrode Steven E. , Muir William W. , O'Dorisio Thomas M. , Masty Jerome
Published: January 2024

Objectives

To describe the acute cellular response, inflammatory mediator release, and effect on chondrocyte metabolism of interleukin 1β (IL-1β) in isolated innervated or denervated equine metacarpophalangeal joints.

Animals

One metacarpophalangeal joint of 24 adult horses.

Procedures

The metacarpophalangeal joint was isolated for 6 hours in a pump-perfused, auto-oxygenated, innervated or denervated metacarpophalangeal joint preparation. Isolated joints were assigned to 4 groups: control, control-denervated, inflamed, and inflamed-denervated, and inflammation was induced by intra-articular injection of IL-1β. Synovial fluid was collected for cytologic examination and determination of IL (IL)-1β, (IL-6), prostaglandin E2 (PGE2), and substance P (SP) values. Synovial membrane was immunostained with SP and nerve-specific enolase (NSE) antibodies. Cartilage was collected for determination of proteoglycan (PG) synthesis and degradation.

Results

IL-1β induced significant neutrophilic leukocytosis in synovial fluid and synovial membrane. IL-1β concentration had returned to baseline by 5.5 hours, but IL-6 concentration significantly increased throughout the study. Total SP content was significantly higher in inflamed joints. There was a significant increase in 24- and 48-hour PG degradation in inflamed innervated joints.

Conclusion

Cellular response to IL-1β was rapid and sustained; joint clearance of IL-1β was rapid, and endogenous production of IL-1β did not follow. The IL-6 and PGE2 concentrations significantly increased, and SP content was increased in association with inflammation but not denervation. A degradative response of cartilage to IL-1β was observed, and was enhanced by innervation. This model was useful for investigation of the articular response to acute inflammation and the influence of denervation in modulating this response. (Am J Vet Res 1998;59:88–100)
Cardiopulmonary effects of anesthesia induced and maintained with isoflurane in cats
Authors: Hodgson David S. , Dunlop Colin I. , Chapman Phillip L. , Grandy Jacqueline L.
Published: January 2024

Objective

To determine the cardiopulmonary effects of anesthesia induced and maintained with isoflurane (ISO) in cats.

Animals

8 healthy cats between 1 and 5 years old.

Procedure

Anesthesia was induced with ISO in oxygen. Two anesthetic depths were maintained in each cat; mean alveolar concentrations (MAC) were 1.3 and 2.0 times MAC. Ventilation was either spontaneous or controlled. Each cat received each treatment combination according to a Latin square design. Cardiopulmonary measurements were made after 20 minutes of constant conditions with each combination of anesthetic depth and ventilatory mode.

Results

Cardiac index was not different between ISO doses, but 2.0 MAC ISO reduced arterial blood pressure and total peripheral resistance. Cardiac index and systolic arterial blood pressure were reduced by controlled ventilation. The PaCO2 and pulmonary artery pressure were highest in association with 2.0 MAC ISO during spontaneous ventilation. Changes in pHa were attributable to changes in PaCO2.

Conclusions

2.0 MAC ISO causes hypotension and hypercapnia; however, cardiac index is maintained. Hypercapnia may be abolished with controlled ventilation, but at the expense of reduced cardiac index. 1.3 MAC ISO results in minimal cardiopulmonary depression, especially when healthy cats are allowed to breathe spontaneously.

Clinical Relevance

Hypoventilation associated with untoward physiologic responses to 2.0 MAC may be overcome with controlled ventilation, but results in marked reduction in cardiovascular performance; thus, use of 2.0 MAC ISO should be avoided in cats. (Am J Vet Res 1998;59:182–185)
Evaluation of digital and laminar blood flow in horses given a low dose of endotoxin
Authors: Ingle-Fehr J. E. , Baxter G. M.
Published: January 2024

Objective

To measure blood flow in the palmar digital artery and laminae corium, using ultrasonic and laser Doppler flowmetry, respectively.

Animals

6 healthy horses.

Procedure

Digital blood flow and laminar perfusion, respectively, were measured by placing a flow probe around the palmar digital artery and a laser Doppler flow probe in a hole in the dorsal aspect of the hoof wall. All horses were given saline (0.9% NaCI) solution (1 L, IV, during a 30-minute period). Seven days later, each horse was given endotoxin (0.1 μg/kg of body weight, IV, in 1 L of saline solution, during a 30-minute period). Digital blood flow, laminar perfusion, heart and respiratory rates, body temperature, and clinical signs of endotoxemia were recorded throughout a 240-minute period. Repeated-measures ANCOVA was used to evaluate changes in outcome variables.

Results

Treatment with saline solution did not cause a change in measured variables. All horses had mild clinical signs of endotoxemia. Endotoxin treatment caused a significant decrease in digital blood flow and increases in heart rate and body temperature. Laminar perfusion decreased after endotoxin treatment.

Conclusions

Endotoxin administration caused a profound transient decrease in digital blood flow and a less substantial decrease in laminar perfusion.

Clinical Relevance

Horses with clinical endotoxemia were likely to have decreased digital blood flow and, possibly, decreased laminar perfusion, potentially predisposing them to vascular alterations within the digits. (Am J Vet Res 1998;59:192–196)
Use of the urine cortisol-to-creatinine ratio for monitoring dogs with pituitary-dependent hyperadrenocorticism during induction treatment with mitotane (o, p'-DDD)
Authors: Randolph John F. , Toomey Jane , Center Sharon A. , Scarlett Janet M. , Reimers Thomas , Graham Peter , Nachreiner Raymond F.
Published: January 2024

Objective

To determine whether the urine cortisol-to-creatinine ratio (UCCR) could replace the ACTH stimulation test in monitoring effectiveness of mitotane induction treatment in dogs with pituitary-dependent hyperadrenocorticism (PDH).

Animals

15 dogs with PDH.

Procedure

All 15 dogs were given an induction dose of mitotane (o, p'-DDD: 35 to 50 mg/kg of body weight/d) for 3 to 14 days. During the induction period, free-catch morning urine samples were collected for determination of UCCR, followed by ACTH stimulation testing, every other day. Treatment response was divided into 3 categories: well-controlled PDH (post-ACTH serum cortisol concentration ≥ 28 nmol/L but ≤ 138 nmol/L), deficient cortisol secretion (post-ACTH serum cortisol concentration < 28 nmol/L), and excess cortisol secretion (post-ACTH serum cortisol concentration > 138 nmol/L).

Results

The linear relation between UCCR and post-ACTH serum cortisol concentration was significant (P < 0.001); however, the prediction intervals surrounding the line were too broad to be clinically useful. The UCCR overlapped among the 3 categories of treatment response. Nevertheless, dogs with PDH receiving mitotane induction treatment and with UCCR > 79 × 10−6 were always classified as having excess cortisol secretion.

Conclusion and Clinical Relevance

The UCCR failed to predict post-ACTH cortisol concentration during mitotane induction treatment sufficiently close to be a clinically reliable indicator of treatment control. Seemingly, however, UCCR > 79 × 10−6 obtained from a dog with PDH during mitotane induction would indicate inadequate adrenal cortex destruction and the need for continued mitotane induction; UCCR ≤ 79 × 10−6 would be inconclusive. (Am J Vet Res 1998;59:258–261)
Effect of α-chymotrypsin on breaking strength and ultrastructural morphology of canine ciliary zonules
Authors: Halenda Ruth Marrion , Nasisse Mark P. , Dykstra Michael J.
Published: January 2024

Objective

To determine the effect of α-chymotrypsin treatment on breaking strength and ultrastructural morphology of canine ciliary zonules.

Sample Population

Eyes from young random-source dogs from an animal shelter.

Procedure

Eyes were obtained immediately after euthanasia of dogs. The enzyme α-chymotrypsin was applied to the ciliary zonules of 1 eye of each dog; the other eye was treated with saline solution as a control. The breaking strength of ciliary zonules was measured, using a linear actuator and force transducer. The lenses and ciliary bodies were then analyzed by scanning and transmission electron microscopy.

Results

α-Chymotrypsin reduced the breaking strength of ciliary zonules by a mean ± SD 44 (± 20)%, compared with that for saline-treated control eyes. Increasing the volume of enzyme further decreased the breaking strength of the zonules. Differences in the appearance of the ciliary body by electron microscopy were not apparent between enzyme- and saline-treated specimens.

Conclusions and Clinical Relevance

Application of α-chymotrypsin to enucleated canine eyes at a concentration used in people significantly reduces the breaking strength of canine ciliary zonules without any apparent damage to the ciliary body. α-Chymotrypsin may be useful in the removal of subluxated canine lenses and in removal of cataractous lenses in young dogs, in which phacoemulsification often results in appreciable post operative capsular opacification. (Am J Vet Res 1998;59:335–339)
Use of an in vitro biotinylation technique for determination of posttransfusion viability of stored canine packed red blood cells
Authors: Wardrop K. Jane , Tucker Russell L. , Anderson Eric P.
Published: January 2024

Objective

To determine posttransfusion viability (PTV) of canine RBC stored for 35 days in an additive solution, using in vitro biotinylation and technetium-99m and chromium-51 (99mTc/51Cr) labeling techniques.

Sample Population

6 random source, adult dogs.

Procedure

RBC from dogs were labeled with N-hydroxysuccinimide biotin (NHS-biotin) or 99mTc/51Cr in a crossover design. One unit (450 ml) of whole blood was collected from each dog, processed into packed RBC, and stored for 35 days in an additive solution. The process was repeated at a later date, so that each dog had 2 units stored under similar conditions. Stored autologous RBC were then labeled with either NHS-biotin or 51Cr and reinfused. When 51Cr was used, labeled cells were infused simultaneously with freshly drawn cells labeled with 99mTc. Posttransfusion viability of labeled cells was determined by dividing counts per minute (99mTc/51Cr) or percentage of cells (NHS-biotin) labeled at 24 hours by counts per minute or percentage of cells labeled after infusion.

Results

Mean PTV of packed RBC stored for 35 days in an additive system was 80% when determined by biotinylation, 83% as determined by 99mTc/51Cr, and 81% as determined by 51Cr alone.

Conclusions

In vitro biotinylation provides an acceptable, nonradioisotopic means of determining PTV of stored canine packed RBC.

Clinical Relevance

NHS-biotin can be used to determine maximal storage time of canine RBC prepared for transfusion purposes. (Am J Vet Res 1998;59:397–400)
Influence of atipamezole on effects of midsacral subarachnoidally administered detomidine in mares
Authors: Skarda Roman T. , Muir William W.
Published: January 2024

Objective

To examine effects of atipamezole on detomidine midsacral subarachnoidally-induced analgesia, cardiovascular and respiratory activity, head ptosis, and position of pelvic limbs in healthy mares.

Animals

10 healthy mares.

Procedure

Using a randomized, blinded, crossover study design, mares received detomidine (0.03 mg/kg of body weight, diluted in 3 ml of CSF) midsacral subarachnoidally, followed by atipamezole (0.1 mg/kg [test]) or sterile saline (0.9% NaCl) solution (control), IV 61 minutes later and saline solution (3 ml, midsacral subarachnoidally) on a separate occasion, at least 2 weeks later. Analgesia was determined by lack of sensory perception to electrical stimulation at the perineal dermatome and no response to needle-prick stimulation extending from the coccygeal to T15 dermatomes. Arterial acid-base (pH, standard bicarbonate, and base excess values), gas tensions (PO2, PCO2), PCV, total solids concentration, heart and respiratory rates, rectal temperature, and arterial blood pressure were determined, and mares were observed for sweating and urination. Mean scores of perineal analgesia, head ptosis, position of pelvic limbs, and cardiovascular and respiratory data were compared for the 3-hour test period.

Results

Subarachnoidally administered detomidine induced perineal analgesia (mean ± SD onset, 9.0 ± 4.6 minutes; duration, 130 ± 26 minutes), marked head ptosis, moderate changes in pelvic limb position, cardiovascular and respiratory depression, sweating in analgesic zones, and diuresis. Intravenously administered atipamezole significantly reduced mean scores of detomidine-induced perineal analgesia, head ptosis, pelvic limb position, sweating and diuresis; partially antagonized detomidine-induced bradycardia; and did not effect detomidine-induced bradypnea.

Conclusions and Clinical Relevance

Most effects of midsacral subarachnoidally administered detomidine, except bradycardia and bradypnea, were reversed by atipamezole (0.1 mg/kg, IV), indicating that most of the actions of detomidine were mediated via activation of α2-adrenergic receptors. (Am J Vet Res 1998;59:468–477)
Effect of a competitive inhibitor of platelet aggregation on experimentally induced laminitis in ponies
Authors: Weiss Douglas J. , Evanson Oral A. , McClenahan David , Fagliari José J. , Dunnwiddie Christopher T. , Wells Roger E.
Published: January 2024

Objectives

To determining whether inhibition of platelet aggregation prevents development of carbohydrate overload-induced alimentary laminitis.

Animals

22 healthy adult ponies.

Procedures

Acute laminitis was induced by oral administration of corn starch/wood flour to 16 ponies, 8 of which were treated with a synthetic analogue of the platelet fibrinogen receptor antagonist peptide (RPR) RGDS (arginine-glycine-aspartic acid-serine) 110885; 6 ponies served as negative controls. Blood was collected before and at 4, 8, 12, 24, 28, and 32 hours after administration of carbohydrate overload, and PCV, total plasma protein concentration, platelet count, activated clotting time, whole blood recalcification time, spontaneous platelet aggregation, ex vivo platelet aggregation responses, in vivo platelet activation, and platelet-neutrophil aggregates were evaluated.

Results

Of 16 ponies given carbohydrate, 6 of 8 untreated ponies developed laminitis and 0 of 8 ponies treated with RPR 110885 developed laminitis. The RPR 110885 treatment attenuated the increase in platelet-neutrophil aggregates observed in untreated ponies.

Conclusions

Platelets are involved in the pathogenesis of equine alimentary laminitis.

Clinical Relevance

Platelet aggregation inhibitors may be useful for prevention or treatment of laminitis, or both. (Am J Vet Res 1998;59:814–817)
Management and environmental risk factors for Salmonella enteritidis contamination of eggs
Authors: Henzler David J. , Kradel David C. , Sischo William M.
Published: January 2024

Objective

To analyze data for 60 poultry flocks voluntarily enrolled in the Pennsylvania Salmonella enteritidis Pilot Project and determine management and environmental risk factors associated with production of S enteritidis-contaminated eggs.

Sample Population

60 flocks for which at least 1 environmental sample (manure or egg-handling equipment) was positive for S enteritidis.

Procedure

Samples of manure, egg-handling equipment, and mice were submitted for bacterial culture of S enteritidis. When S enteritidis was isolated from environmental samples, 1,000 eggs were collected from the flock every 2 weeks for 8 weeks and submitted for bacterial culture.

Results

18 flocks were found to have produced contaminated eggs. Estimated overall prevalence of contaminated eggs was 2.64/10,000 eggs produced, but flock-specific prevalence ranged from 0 to 62.5/10,000 eggs. Flocks with high levels of manure contamination were 10 times as likely to produce contaminated eggs as were flocks with low levels. However, 5 flocks with low levels of manure contamination produced contaminated eggs.

Conclusions

Evaluation of the level of manure contamination could be used to help identify flocks at risk of producing S enteritidis-contaminated eggs.

Clinical Relevance

Flocks with high levels of S enteritidis-contaminated manure appeared to pose the greatest public health threat, and on-farm programs to reduce the prevalence of egg contamination should be developed for farms with high levels of manure contamination. Efforts to reduce the overall number of on-farm pathogens should decrease the incidence of foodborne disease in humans. (Am J Vet Res 1998;59:824–829)
Evaluation of the effects of omega-3 fatty acid-containing diets on the inflammatory stage of wound healing in dogs
Authors: Mooney Mark A. , Vaughn Dana M. , Reinhart Gregory A. , Powers Robert D. , Wright James C. , Hoffman Charles E. , Swaim Steven F. , Baker Henry J.
Published: January 2024

Objectives

To ascertain the effects of dietary omega-3 (n-3) fatty acids on biochemical and histopathologic components of the inflammatory stage of wound healing.

Animals

30 purpose-bred Beagles.

Procedure

Dogs were allotted to 5 groups of 6. Each group was fed a unique dietary fatty acid ratio of omega-6 to n-3—diet A, 5.3:1; diet B, 10.4:1; diet C, 24.1:1; diet D, 51.6:1; and diet E, 95.8:1. Dogs were fed once daily for 12 weeks, then biopsy specimens were taken from 4-day-old wounds of each dog and analyzed by gas chromatography-mass spectrometry for: prostaglandin E2 (PGE2) metabolites, and ratios of omega-6 to n-3 fatty acids, arachidonic acid (AA) to eicosapentaenoic acid (EPA), adrenic acid to docosahexaenoic acid, and PGE2 to prostaglandin E3 (PGE3) metabolites.

Results

Qualitative analysis was carried out on AA, EPA, adrenic acid, docosahexaenoic acid, and the major metabolite from the PGE2 and PGE3 pathway. These molecules were further quantified with respect to diet to determine significant differences. By analysis of the AA-to-EPA ratio, diet A was different from diets D and E and diets B and C were different from diet E (P < 0.05). By analysis of the PGE2-to-PGE3 metabolite ratio, diet A was different from diet E (P < 0.05). Though biochemical analysis indicated dietary dependence, histopathologic data indicated no significant difference with respect to diet groups.

Conclusion

The biochemical component of the inflammatory stage of wound healing can be manipulated by diet.

Clinical Relevance

Omega-3 fatty acid-enriched diets can be used to control inflammation associated with dermatologic conditions. (Am J Vet Res 1998;59:859–863)
Blood mineral and vitamin E concentrations in llamas
Authors: Smith Bradford B. , Van Saun Robert J. , Reed Pamela J. , Craig A. Morrie , Youngberg Annette
Published: January 2024

Objective

To establish reference values for blood concentrations of total calcium (Ca), inorganic phosphorus (P), iron (Fe), copper (Cu), zinc (Zn), selenium (Se), and vitamin E (Vit E) in clinically normal llamas.

Animals

270 llamas ranging in age from < 1 month to > 15 years and grouped by age, sex, pregnancy status, and stage of gestation. Selected llamas were from 21 farms in Oregon, did not have previous health problems, and met specific health criteria on examination.

Procedure

Serum and blood samples were obtained and analyzed for concentrations of Ca, P, Fe, Cu, Se, Zn, and Vit E, and total iron binding capacity (TIBC) and percentage of transferrin saturation (% Sat). Mean differences by age, sex, pregnancy status, and stage of gestation, as well as all interactions, were compared to establish reference values.

Results

Mean values and reference ranges for most of the minerals and vitamins were similar to previously reported values. Male versus female differences were not identified for any measurements. Age was a significant variable for Ca, P, Fe, and Se concentrations, as well as Ca-to-P ratio and TIBC. Identified age-based effects were modeled by use of linear regression. Copper and Zn concentrations and % Sat did not differ as a function of age. Serum Vit E concentration was influenced by an age by sex interaction and stage of gestation.

Conclusions

Age was found to be an important variable influencing many blood nutrient concentrations in healthy llamas.

Clinical Relevance

Clinical diagnosis of metabolic disease may be improved with use of age-based reference values, especially for neonates. (Am J Vet Res 1998;59:1063–1070)
Evaluation of cow-level risk factors for the development of winter dysentery in dairy cattle
Authors: Smith David R. , Fedorka-Cray Paula J. , Mohan Ram , Brock Kenny V. , Wittum Thomas E. , Morley Paul S. , Hoblet Kent H. , Saif Linda J.
Published: January 2024

Objective

To identify exposures to etiologic agents and to identify characteristics that could explain risk of disease for adult cattle in herds affected by winter dysentery (WD).

Animals

229 lactating and nonlactating adult cattle (125 case and 104 control cattle) selected from 12 dairy herds.

Procedure

A case-control study, using multivariate conditional logistic regression and controlling for herd effects, was used to develop a model for risk factors associated with disease for each cow.

Results

Likelihood of developing disease increased as the ELISA value for bovine coronavirus (BCV) antigen detectable in feces increased (odds ratio [OR] = 2.94 for each 0.100 increase in BCV antigen ELISA value). Pregnant cattle were less likely to develop WD, compared with nonpregnant herdmates. Cows with high acute BCV antibody titers that seroresponded had greater odds of developing disease, compared with seroresponding cows with low acute titers. However, among those cows that did not serorespond, high acute antibody titers were associated with lower odds of developing the disease.

Conclusion

In herds affected by WD, ill cows were more likely to shed detectable amounts of BCV antigen in their feces, and pregnancy appeared to protect cattle from the disease. The measured interaction between BCV seroresponse and acute BCV antibody titer may be evidence of an immunopathologic condition, but could also have been attributable to dynamics of the ELISA or study design.

Clinical Relevance

Factors that explained a cow's risk for illness within WD-affected herds may have been surrogate measures for that cow's nonspecific and BCV-specific immune profile. (Am J Vet Res 1998;59:986–993)
Physiologic response to dobutamine infusion during cardiac stress testing of dogs
Authors: McEntee Kathleen , Amory Hélène , Clercx Cécile , Soyeur Daniel , Michaux Charles , Vanhaeverbeek Olivier , Jacqmot Olivier , Henroteaux Marc
Published: January 2024

Objective

To evaluate response of various cardiovascular variables after administration of incremental doses of dobutamine in healthy conscious dogs, using standardized dobutamine stress echocardiography (DSE).

Animals

8 healthy dogs.

Procedure

A DSE was performed twice on each dog within 24 hours. Dobutamine was infused at a rate of 12.5 to 42.5 μg/kg/min, using incremental increases of 10 μg/kg/min. Doppler sphygmomanometry, electrocardiography, and echocardiography were performed. Left ventricular size, global ventricular performance, and left ventricular systolic myocardial function were measured by means of echocardiography.

Results

At the highest dosage, dobutamine induced an increase of 20 ± 3% and 109 ± 12% in systolic blood pressure and cardiac index, respectively. The latter was associated with a significant increase in heart rate and stroke index. Fractional shortening of the left ventricle, fractional thickening of the left ventricular free wall and interventricular septum, ejection fraction, and mean velocity of fiber shortening had a progressive and significant increase during dobutamine infusion. Preejection period and left ventricular ejection time had a progressive and significative decrease during the stress test.

Conclusions

The technique used was feasable, safe, and repeatable in healthy conscious dogs. Control values were determined.

Clinical Relevance

Data for these healthy dogs might be useful for comparison with results obtained from dogs with known or suspected cardiovascular disease. (Am J Vet Res 1998;59:1160-1165)