bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of thermal environment on response to acute peripheral lipopolysaccharide challenge exposure in neonatal pigs
Authors: Klir John J. , Shahbazian L. Masoud , Matteri Robert L. , Fritsche Kevin L. , Becker B. Ann
Published: January 2024

Objective

To evaluate effects of thermal environment on response to acute peripheral lipopolysaccharide (LPS) challenge exposure in neonatal pigs.

Animals

26 neonatal pigs.

Procedure

Pigs were assigned to the following treatment groups: 1 warm environment/LPS; 2 warm environment/saline solution; 3 cool environment/LPS; and 4 cool environment/saline solution. For each pig given LPS. 1 littermate of the same sex was given saline solution. Sows with baby pigs were housed in a warm (32 C) or cool (21 C) thermal environment. At 28 days of age, pigs were given 150 µg/kg of body weight of Escherichia coli LPS or saline solution intraperitoneally as a control. Rectal temperature and signs of sickness were monitored for 3 hours after LPS administration, when pigs were euthanatized and blood samples were collected to determine serum concentrations of tumor necrosis factor (TNF) α and cortisol. To determine in vitro production of TNFα, alveolar macrophages were collected by tracheal lavage and incubated for 24 hours at 37 or 41 C, with or without LPS (10 µg/ml).

Results

Thermal environment had a significant (P = 0.0004) effect on rectal temperature; LPS administration induced a febrile response (P = 0.0007) only in pigs in the warm environment. All LPS-injected pigs developed signs of endotoxemia; serum TNFα and cortisol concentrations were significantly increased (TNFα, P = 0.003; cortisol, P = 0.0001); there was no significant in vivo thermal effect on serum TNFα and cortisol concentrations. LPS-stimulated alveolar macrophages produced significantly less (P = 0.0086) TNFα when incubated at 41 C.

Conclusions

Thermal environment can have a significant impact on the response of neonatal pigs exposed to bacterial endotoxins. (Am J Vet Res 1997; 58:364-369)
Evaluation of arginine-glycine-aspartate-containing peptides as inhibitors of equine platelet function
Authors: Weiss Douglas J. , Evanson Oral A. , Wells Roger E.
Published: January 2024

Objectives

To determine whether synthetic peptides containing the arginine-glycine-aspartate (RGD) sequence inhibit equine platelet function.

Animals

For in vitro studies of blood, 3 healthy Thoroughbreds; for in vivo and ex vivo studies of administration of RGD-containing peptides, 4 young adult pony mares.

Procedure

Blood was incubated with and without addition of aspirin or RGD-containing peptides (RGDS, RPR 110885) and platelet aggregation responses and platelet adhesion to subendothelial collagen were determined. RPR 110885 was administered IV, and platelet function was evaluated. Platelet aggregation was determined by a turbidimetric method, and platelet adhesion was evaluated by the Baumgartner perfusion method. RPR110885 was administered IV at dosages of 30 and 60 μg/kg of body weight, and bleeding time, platelet aggregation responses, and platelet count were determined at hourly intervals for 4 hours.

Results

Both RGDS and RPR 110885 inhibited platelet aggregation in vitro in dose-dependent manner and inhibited platelet adhesion to subendothelial collagen. The concentration of RGDS that inhibited platelet aggregation by 50% (IC50) was 100 to 142 μM for the various agonists tested, whereas the concentration of RPR 110885 that inhibited platelet aggregation by 50% was 0.03 to 0.05 μM. When administered to ponies at 30 or 60 g/kg, RPR 110885 almost completely inhibited ADP-induced platelet aggregation.

Conclusions

RGDS and RPR 110885 inhibited equine platelet function; however, RPR 110885 was several thousand times more potent than RGDS.

Clinical Relevance

RGD-containing peptides may be useful for treatment of thrombotic diseases of horses. (Am J Vet Res 1997;58:457–460)
Temporal effects of an infusion of dopexamine hydrochloride in horses anesthetized with halothane
Authors: Young L. E. , Blissitt K. J. , Clutton R. E. , Molony V.
Published: January 2024

Objective

To evaluate the hemodynamic effects of a 60-minute infusion of dopexamine in horses anesthetized with halothane.

Animals

7 adult Thoroughbreds.

Procedure

Measurements of left ventricular function obtained by transesophageal Doppler echocardiography and cardiac catheterization.

Results

Infusion of dopexamine (4 μg/kg of body weight/min) significantly increased heart rate, cardiac output, maximal rates of increase and decrease of left ventricular pressure, and maximal acceleration and maximal velocity of aortic blood flow. Left ventricular ejection time significantly increased, and pre-ejection period decreased during the infusion. Cardiac output, maximal rate of increase of left ventricular pressure, and maximal acceleration continued to increase as the infusion progressed. Right ventricular end-diastolic pressure was significantly decreased after 20 minutes of infusion and decreased progressively throughout the remaining time of infusion. Many hemodynamic variables, including right ventricular end-diastolic pressure, had not returned to control values 30 minutes after the infusion was discontinued. A number of undesirable adverse effects were observed in horses receiving dopexamine infusion; during administration, profuse sweating occurred in every horse. In 6 horses, recovery from anesthesia was associated with excitement and violent shivering. Colic developed in 2 horses within 3 hours of recovery.

Conclusions

Dopexamine (4 μg/kg/min) does not achieve a peak effect on many hemodynamic variables within a short period of commencing administration, and the effects of infusion may persist for extended periods after drug administration is discontinued.

Clinical Relevance

Dopexamine has a hemodynamic profile suited to treatment of low cardiac output in anesthetized horses; however, at the dosage rate studied (4 μg/kg/min), its administration was associated with a number of undesirable adverse effects which could preclude its clinical use. (Am J Vet Res 1997;58:516–523)
Muscarinic hyperresponsiveness of antigen-sensitized feline airway smooth muscle in vitro
Authors: Mitchell R. W. , Ndukwu I. M. , Leff A. R. , Padrid P. A.
Published: January 2024

Objective

To determine the effect of in vivo antigen sensitization (Ascaris suum) of cats on tracheal smooth muscle (TSM) and bronchial smooth muscle (BSM) muscarinic reactivity in vitro.

Animals

Healthy domestic shorthair cats of either sex.

Procedure

Cats were sensitized and were longterm antigen (or sham) challenge exposed for 6 weeks by aerosolization with soluble Ascaris suum. Tracheal and BSM preparations were obtained and stimulated in vitro by electrical field stimulation (EFS), acetylcholine (ACh, a muscarinic agonist), and physostigmine (an AChase inhibitor). Responses were compared with responses of comparable tissues from sham antigen challenge-exposed cats.

Results

Tracheal and BSM from sensitized, compared with sham-sensitized (control), cats had greater isometric contraction (expressed as percentage of the response observed for isotonic, 63 mM KCl-elicited contraction [% KCI]) in response to endogenous (EFS) and exogenous muscarinic receptor activation (ACh). Contractions in response to EFS by TSM from control cats were 74 % KCI vs 97 %KCI for antigen-sensitized TSM (P < 0.04). Muscarinic responses were augmented comparably by in vivo sensitization; TSM from control cats contracted to 190 % KCI vs 230 % KCl (P < 0.03) for TSM from immune-sensitized cats. Physostigmine augmented responses of all tissues to ACh so that TSM from control (290 %KCI) and antigen-sensitized (257 %KCI) cats were similar. Responses of BSM from antigen-sensitized cats had similar augmentation of contractile response to EFS and ACh.

Conclusions

Long-term in vivo antigen sensitization increases numbers of muscarinic receptors on airway smooth muscle or decreases the availability or activity of AChase in cats.

Clinical Relevance

Modulation of muscarinic receptors may be useful for treatment of asthmatic cats with in vivo airway hyperreactivity. (Am J Vet Res 1997;58:672–676)
Endocrine changes in cerebrospinal fluid, pituitary effluent, and peripheral plasma of anesthetized ponies
Authors: Luna Stelio P. L. , Taylor Polly M. , Bloomfield Malcolm
Published: January 2024

Objective

To investigate the effects of inhalation and total IV anesthesia on pituitary-adrenal activity in ponies.

Animals

9 healthy ponies: 5 geldings and 4 mares.

Procedure

Catheters were placed in the cavernous sinus below the pituitary gland and in the subarachnoid space via the lumbosacral space. After 72 hours, administration of acepromazine was followed by induction of anesthesia with thiopentone and maintenance with halothane (halothane protocol), or for the IV protocol, anesthesia induction with detomidine and ketamine was followed by maintenance with IV infusion of a detomidine-ketamine-guaifenesin combination. Arterial blood pressure and gas tensions were measured throughout anesthesia. Peptide and catecholamine concentrations were measured in pituitary effluent, peripheral plasma, and CSF. Peripheral plasma cortisol, glucose, and lactate concentrations also were measured.

Results

Intravenous anesthesia caused less cardiorespiratory depression than did halothane. ACTH, metenkephalin, arginine vasopressin, and norepinephrine pituitary effluent and peripheral plasma concentrations were higher during halothane anesthesia, with little change during intravenous anesthesia. Pituitary effluent plasma β-endorphin and peripheral plasma cortisol concentrations increased during halothane anesthesia only. Dynorphin concentrations did not change in either group. Hyperglycemia developed during intravenous anesthesia only. Minimal changes occurred in CSF hormonal concentrations during anesthesia.

Conclusion

The pituitary gland has a major role in maintaining circulating peptides during anesthesia. Compared with halothane, IV anesthesia appeared to suppress pituitary secretion. (Am J Vet Res 1997;58:765–770)
Vitreous body glutamate concentration in dogs with glaucoma
Authors: Brooks D. E. , Garcia G. A. , Dreyer E. B. , Zurakowski D. , Franco-Bourland R. E.
Published: January 2024

Objective

To analyze the vitreal amino acid concentrations in dogs with breed-related primary glaucoma to determine whether excitotoxic amino acids associated with retinal ganglion cell death in other species were present in affected dogs.

Samples

11 normal control and 10 glaucomatous canine eyes.

Procedure

Amino acid analyses were performed by high-pressure liquid chromatography in masked manner.

Results

Eyes from dogs with primary glaucoma had significantly high vitreal glutamate concentration, compared with values for eyes of clinically normal control dogs. Mean (± SD) glutamate concentrations were 31.7 ± 12.4 and 6.9 ± 6.3 μM in glaucomatous and normal eyes, respectively (P < 0.0001). Eyes from dogs with glaucoma also had lower vitreal glycine (37.0 ± 17.0 vs 59.4 ± 28.2 μM; P < 0.043) and higher of vitreal tryptophan (39.0 ± 22.8 vs 17.5 ± 11.2 μM; P < 0.012) concentrations, compared with values for normal eyes.

Conclusion

Glutamate concentration potentially toxic to retinal ganglion cells is associated with the pathogenesis of primary glaucoma in dogs. Increased glutamate concentration provides evidence of an ischemic mechanism for retinal ganglion cell death and optic nerve atrophy in dogs with glaucoma.

Clinical Relevance

The emphasis on reduction and normalization of high intraocular pressure as the primary focus of treatment for glaucoma in dogs should be augmented by other therapeutic approaches. (Am J Vet Res 1997;58:864–867)
Immunocytochemical localization of adrenocorticotropic hormone-immunoreactive cells of the pars intermedia in Thoroughbreds
Authors: Okada Toshiya , Shimomuro Takeaki , Oikawa Masaaki , Nambo Yasuo , Kiso Yasuo , Morikawa Yoshio , Liptrap Robert M. , Yamashiro Shigeto , Little Peter B. , Sasaki Fumihiko
Published: January 2024

Objective

To analyze and characterize adenoma and hyperplasia of the pars intermedia (PI) of Thoroughbred mares.

Animals

165 Thoroughbred mares, without clinical signs of hyperadrenocorticism that had been euthanatized or had died, of causes such as sudden death, colic, pneumonia, or trauma, and were necropsied. Five of those horses, 17 to 25 years old, had a large pituitary gland at necropsy. Eight mares, 5 to 15 years old with normal-size pituitary gland, were selected at random for comparison.

Procedure

A morphologic comparison of the pituitary gland between horses with and without tumors of the PI was conducted by use of immunocytochemistry and morphometry.

Results

In horses with normal pituitary gland, the PI was supplied by a vast capillary or sinusoidal plexus, which connected that in the pars distalis (PD) with that in the pars nervosa (PN). Cells of the PI stained slightly with ACTH antiserum, but some cells in the border region, which is contiguous to the PD, were strongly ACTH immunoreactive. At necrospy, horses with an enlarged pituitary gland also had adenoma of the pituitary gland involving the PI. Cells of the border region were hypertrophied and stained strongly with ACTH antiserum. The area and number of individual tumor cells of the border region of the PI of horses with adenoma were significantly increased, compared with those in horses with normal pituitary gland.

Conclusions

Cells of the PI-PD border region may secrete substantial quantities of ACTH, owing to stimulation by corticotropin-releasing factor. Adenoma and hyperplasia of the PI in Thoroughbred mares may be associated with hyperadrenocorticism. (Am J Vet Res 1997;58:920–924)
Field trial to evaluate the immunogenicity of pseudorabies virus vaccines with deletions for glycoproteins G and E
Authors: Firkins Lawrence D. , Weigel Ronald M. , Biehl LeRoy G. , Hahn Edwin C.
Published: January 2024

Objective

To evaluate, under field conditions, the immunogenicity of 2 pseudorabies virus (PRV) vaccines (each with deletion of the gene for glycoprotein G [gG], and 1 with an additional deletion for glycoprotein E [gE]), particularly in the presence of maternal antibodies, and to investigate the effect of vaccination schedules in overcoming maternal antibody interference with vaccination.

Sample Population

Two cohorts of 105 growing pigs each on a PRV-seronegative commercial swine farm where breeding stock had been vaccinated with a PRV vaccine containing deletions of genes for gG and gE.

Procedure

Within each cohort, pigs were randomly assigned to 1 of 7 treatment groups. For each vaccine, vaccination was done at 8, 12, or 8 and 12 weeks of age. One group remained unvaccinated. Blood and nasal swab specimens were obtained at 8, 10, 12, 14, and 16 weeks of age, and the immune response was measured, by use of an ELISA.

Results

In cohort 1, where prevalence of maternal antibodies at 8 weeks of age was lower, an immune response lasting until 16 weeks of age was induced in most pigs by either vaccine. In cohort 2, where prevalence of maternal antibodies at 8 weeks of age was higher, the gG-gE- vaccine elicited a lower immune response in the presence of maternal antibodies than did the gG- vaccine after single vaccination at 8 weeks of age. This maternal antibody interference with the response to vaccination was evident in serum and nasal mucosal antibodies.

Conclusions

The gE deletion decreases the immunogenicity of PRV vaccine in the presence of maternal antibodies. Although evidence of maternal antibody interference for the gG- vaccine existed, its immunogencity was diminished less in the presence of maternal antibodies than that of the gG-gE- vaccine. (Am J Vet Res 1997;58:976–984)
Dietary modulation of methotrexate-induced enteritis in cats
Authors: Marks Stanley L. , Cook Audrey K. , Griffey Stephen , Kass Philip H. , Rogers Quinton R.
Published: January 2024

Objective

To determine effects of purified and dry expanded (complex) diets on intestinal structure and function in healthy cats and in a feline model of methotrexate-induced enteritis.

Animals

19 adult specific-pathogen-free cats.

Procedure

Cats were randomized in groups to receive a purified diet intragastrically or a complex diet orally to meet their daily metabolizable energy requirements. After 21 days, cats received either methotrexate (MTX; 10 mg/kg of body weight, IV, n = 12) or saline solution IV (n = 7), and were anesthetized 72 hours later. Celiotomy was performed for aseptic removal of mesenteric lymph nodes, full-thickness biopsy of the gastrointestinal tract, and collection of aortic and portal venous blood samples for determination of arteriovenous amino acid concentrations across the intestine.

Results

MTX was associated with severe enterotoxicosis in cats receiving the purified diet, as manifested by diarrhea (4 of 6 cats) and vomiting (2 of 6 cats). One cat receiving the complex diet developed mild diarrhea, and none of these cats vomited. The purified diet was associated with marked villus blunting in the proximal and distal portions of the duodenum and increased bacterial translocation (3 of 6 cats), whereas none of the cats in the complex diet group developed bacterial translocation after MTX administration. For the cats given saline solution, bacterial translocation occurred in 1 of 4 cats receiving the complex diet versus 2 of 3 cats receiving the purified diet.

Conclusions

Feeding of a complex diet containing intact protein as the nitrogen source abrogated the proximal small intestinal atrophy and bacterial translocation associated with feeding an amino acid-based purified diet.

Clinical Relevance

Use of purified diets containing free amino acids as the only nitrogen source cannot be endorsed in human and animal cancer patients receiving systemic chemotherapy. (Am J Vet Res 1997;58:989–996)
Use of transabdominal ultrasound-guided amniocentesis for detection of equid herpesvirus 1-induced fetal infection in utero
Authors: Smith Kenneth C. , McGladdery Andrew J. , Binns Matthew M. , Mumford Jennifer A.
Published: January 2024

Objective

To evaluate transabdominal ultrasound-guided amniocentesis for detection of equid herpesvirus 1 (EHV-1)-induced fetal infection in utero.

Animals

4 Welsh Mountain mares.

Procedure

Pregnant mares were inoculated intranasally with EHV-1 during the ninth month of gestation. Amniocentesis was initiated on postinoculation day (PID) 12, and was performed at 2- to 3-day intervals in standing mares under deep sedation. Amniotic fluid samples were tested by virus isolation (VI), polymerase chain reaction (PCR), and immunoperoxidase cytologic examination (IC) for detection of EHV-1.

Results

Exposure to EHV-1 in the ninth month of gestation resulted in nasal shedding of infective virus, establishment of cell-associated viremia, and seroconversion. Equid herpesvirus 1 was detected by VI, PCR, and IC in amniotic fluid collected on PID 14 from 1 mare and on PID 16 and 17 from a second mare. Specimens of amniotic fluid from a third mare were VI negative until PID 18, when collections ceased, although this mare subsequently aborted an EHV-1-infected fetus on PID 28. The fourth mare aborted an EHV-1 infected fetus on PID 14. The 2 mares with VI-positive amniotic fluid were each carrying an EHV-1 infected fetus in utero, confirmed by examination of the uterus, placenta, and fetus, using specific immunohistochemistry and in situ hybridization. Endothelial cells in the endometrium and allantochorion were often virus-infected, with accompanying vascular lesions. The fetus had been infected via the chorionic vasculature in the first and fourth mares, and by inhalation of infected amniotic fluid in the second mare.

Conclusion

Amniocentesis permits specific detection of EHV-1-induced fetal infection in utero.

Clinical Relevance

Amniocentesis may have a clinical role in the specific identification and isolation of mares carrying virus-infected fetuses during EHV-1- induced abortion epizootics. (Am J Vet Res 1997;58:997–1002)
Biomechanical characterization of passive laxity of the hip joint in dogs
Authors: Smith Gail K. , LaFond Elizabeth , Heyman Steven J. , Cofone Mark A. , Gregor Thomas P.
Published: January 2024

Objective

To investigate the in vitro load/displacement characteristics of the hip joints in dogs as a function of joint position.

Sample Population

10 hip joints from 5 healthy dogs.

Procedure

A material test system was used to generate load/displacement curves for each joint. Joints were mounted in a custom-designed jig that held the joint in fixed anatomic orientations while plotting displacement and corresponding applied loads. All hips were cycled between 40 N of compression and 80 N of distraction. Each hip was tested at 10° increments from 30° flexion to 70° extension.

Results

When the hips were in a neutral orientation (approximately a standing position), load/displacement curves were characteristically sigmoidal (tri-phasic), indicating that, in this position, displacement was not highly dependent on load. The curves had a central low-stiffness region in which most of the lateral displacement took place. In contrast, when hips were positioned at the extremes of flexion and extension, this central, low-stiffness region was less distinct, and load/displacement curves were more linear, indicating a proportional relation between load and displacement. The load/displacement curve of 1 hip joint in the study deviated markedly from the others in a pattern consistent with cavitation of the synovial fluid.

Conclusions

When the hip joint is positioned in a neutral position, load-displacement behavior is sigmoidal, whereas when the hip joint is in an extended position, load/displacement behavior is more linear.

Clinical Relevance

Establishing load/displacement behavior of the hip joints in dogs was an important exercise in establishing the position for and estimating the repeatability of a clinical stress-radiographic method for quantitating joint laxity in dogs. (Am J Vet Res 1997;58:1078–1082)
Flow cytometric method for detecting thiazole orange-positive (reticulated) platelets in thrombocytopenic horses
Authors: Russell Karen E. , Perkins Paula C. , Grindem Carol B. , Walker Kathy M. , Sellon Debra C.
Published: January 2024

Objective

To evaluate a method for detecting thiazole orange-positive (TO+, reticulated) platelets in equine blood, using flow cytometry.

Animals

16 healthy, equine infectious anemia virus (EIAV)-negative horses and ponies; 9 thrombocytopenic, ElAV-positive horses and ponies; and 2 thrombocytopenic, ElAV-negative horses.

Procedure

Blood from healthy and thrombocytopenic horses was collected by jugular venipuncture. Appropriate sample requirement and incubation time for the assay were evaluated, using blood anticoagulated with EDTA or sodium citrate, or platelet-rich plasma in sodium citrate. The sample of blood or platelet-rich plasma was incubated with thiazole orange, and flow cytometric analysis was performed. Percentage of circulating TO+ platelets was determined from fluorescence (FL-1) logarithmic histograms.

Results

Healthy ponies (n = 9) had 1.28 to 2.83% (mean ± SD, 2.03 ± 0.50%) and horses (n = 7) had 0.9 to 3.44% (2.12 ± 1.14%) TO+ platelets in circulation. Thrombocytopenic ponies (n = 7) had 11.14 to 48.41 % (26.51 ± 11.99%) and thrombocytopenic horses (n = 4) had 2.33 to 8.52% (6.19 ± 2.68%) TO+ platelets in circulation. Mean platelet counts for the thrombocytopenic ponies and horses were 24,400 ± 20,500 and 39,300 ± 13,500 platelets/μl, respectively (reference range, 94,000 to 232,000 platelets/μl).

Conclusion

Thiazole orange-positive platelets can be detected in equine blood and percentages of TO+ platelets are increased in thrombocytopenic horses.

Clinical Relevance

Enumeration of TO+ platelets may prove to be a helpful noninvasive clinical measurement of bone marrow platelet production and aid in the assessment of platelet kinetics in thrombocytopenic horses. (Am J Vet Res 1997;58:1092–1096)
Infection of polarized epithelial cells with enteric and respiratory tract bovine coronaviruses and release of virus progeny
Authors: Lin Xiaoqing , O'Reilly Kathy L. , Storz Johannes
Published: January 2024

Objective

To investigate the susceptibility of polarized epithelioid human rectal tumor (HRT-18G) cells to bovine coronaviruses (BCV) isolated from enteric (EBCV) and respiratory (RBCV) tract infections.

Procedure

Cells of the G clone of HRT-18 were grown to confluent monolayers on permeable supports, and were directionally infected at the apical and basolateral domains with 3 wild-type BCV strains, RBCV-LSU-94LSS-051-2, RBCV-OK-0514-3, and EBCV-LY138-2, and 1 cell culture-adapted strain, EBCV-L9-80. Sequential cytopathic changes were microscopically monitored. Medium samples for titration of hemagglutinins and viral infectivity were collected directionally from both domains of the infected cell cultures at various intervals.

Results

Polarized epithelioid HRT-18G cells from apical domains had maximal susceptibility to infection with the EBCV and RBCV strains, and those from basolateral surfaces had minimal susceptibility. Titers of hemagglutinins and infective progeny BCV reached 1,280 hemagglutinin units and 4.2 × 108 plaque-forming units/ml for apical samples, but were minimal for basolateral samples. Asymmetric virus release occurred through the apical surfaces of the HRT-18G cells by 12 hours after infection when cell fusion as a sign of cytopathic changes began. When cells were infected basolaterally, progeny virions released from apical surfaces reinfected the target cells from the apical domains and induced cytopathic changes were delayed about 12 hours, compared with changes detectable in apically exposed cultures.

Conclusions

EBCV and RBCV, isolated from cattle, had marked tropism for polarized epithelioid HRT-18G cells. Entry of BCV into the polarized HRT-18G cells was effected maximally through the apical domains and minimally through the basolateral domains. Release of progeny BCV occurred preferentially from the apical domains. (Am J Vet Res 1997;58:1120–1124)
Mechanisms of acute intraocular pressure increases after phacoemulsification lens extraction in dogs
Authors: Miller Paul E. , Stanz Kimberly M. , Dubielzig Richard R. , Murphy Christopher J.
Published: January 2024

Objective

To investigate the mechanisms by which intraocular pressure (IOP) increases acutely after phacoemulsification (PE) lens extraction in clinically normal dogs.

Animals

24 young adult dogs.

Procedure

Intraocular pressure was monitored for up to 24 hours after unilateral intercapsular PE in 17 clinically normal, adult dogs. In 8 of these dogs, use of 2% hydroxypropyl methylcellulose (HPMC) aided capsulorhexis. Mean volume of irrigation, PE time, and power were constant between groups. After surgery, dogs were randomized then euthanatized, and eyes were examined grossly and histologically at 0 (n = 4), 3 (n = 7), and 24 hours (n = 6) after PE. Seven additional dogs underwent anterior chamber decompression alone (n = 4) or served as morphologic controls (n = 3).

Results

Intraocular pressure peaked by postoperative hour 3 at 49.9 ± 5.0 mm of Hg and normalized by 24 hours. Use of HPMC did not affect the peak or duration of IOP increase. Blood refluxed into the collecting channels and corneoscleral trabecular mesh-work in operated eyes. Computer-aided morphologic analysis indicated significant (P < 0.001) reduction in ciliary cleft cross-sectional surface area and width immediately after PE, but not after anterior chamber decompression alone. Cleft collapse was significantly (P < 0.02) greater at 24 than at 3 hours, despite return of IOP to control values by 24 hours. Plasmoid aqueous also was found in the meshwork.

Conclusions and Clinical Relevance

Sudden, large increases in IOP with few overt clinical signs may occur immediately after lens extraction in dogs. Such increases risk compromising the corneal incision and may damage the optic nerve, thereby complicating lens extraction. Structural alterations in the trabecular meshwork persist after IOP has normalized in 24 hours and may contribute to genesis of glaucoma in the late postoperative period. (Am J Vet Res 1997;58:1159–1165)
Effects of selection and habituation on vertical ground reaction force in Greyhounds
Authors: Rumph Paul F. , Steiss Janet E. , Montgomery Ronald D.
Published: January 2024

Objective

To determine effect of dog selection and habituation on vertical ground reaction force variables.

Animals

133 Greyhounds of either sex, weighing between 22 and 39 kg.

Procedure

Vertical ground reaction force variables (peak [PFz] and impulse [IFz]) for hind limbs were studied in dogs at 3 levels of habituation. Dogs of group 1 (n = 81) did not have prior experience with the gait analysis routine. Group-2 dogs (n = 52) were selected for having an amiable disposition, and were first evaluated after participating in an intermediate habituation routine (group 2a). These dogs were reevaluated after undergoing the full habituation routine (group 2b).

Results

3 of the ground reaction force variables differed significantly between dogs of groups 1 and 2 (a and b). Dogs that had not been habituated to the gait analysis routine (group 1) had significantly longer stance times than did dogs that had been more carefully selected and habituated. Intradog coefficients of variation for PFz and the IFz were significantly greater in group-1 dogs. The PFz for group-2a dogs was significantly greater than that for group-1 dogs. Differences identified between groups 2a and 2b were more likely to be attributed to habituation only. These included significantly shorter stance time and lower intradog coefficient of variation for IFz in dogs having the highest level of habituation.

Conclusion

Selection and habituation have measurable effects on vertical ground reaction force data obtained from trotting dogs. These include significantly shorter hind limb stance times, lower impulses of vertical force, with smaller coefficients of variation for peaks and impulses of vertical force within dogs.

Clinical Relevance

In controlled studies where critical decision making is based on gait analysis data, careful selection of subjects and habituation will significantly improve precision of the data and has the potential to reduce the subject or repetition sample size. (Am J Vet Res 1997;58:1206–1208)
Cardiovascular effects of buprenorphine in anesthetized dogs
Authors: Martinez Elizabeth A. , Hartsfield Sandee M. , Melendez Linda D. , Matthews Nora S. , Slater Margaret R.
Published: January 2024

Objective

To determine the cardiovascular effects of buprenorphine in isoflurane-and halothane-anesthetized dogs.

Animals

6 healthy adult hound-type dogs given buprenorphine (16 μg/kg of body weight, IV) or isovolumetric 5% dextrose solution during anesthesia with isoflurane or halothane.

Procedure

Each dog was anesthetized 4 times, with a minimum of 10 days between episodes. Anesthesia was induced with isoflurane or halothane in O2 by mask, and was maintained with 1.9% isoflurane or 1.3% halothane (end-tidal concentration). The Paco2 was maintained between 35 and 45 mm of Hg by use of mechanical ventilation, and the following variables were determined: systolic, diastolic, and mean arterial blood pressures; cardiac output; cardiac index; stroke volume; heart rate; systemic vascular resistance; mean pulmonary arterial pressure; and pulmonary vascular resistance. In addition, arterial blood samples for gas and acid-base analyses were collected at 30-minute intervals for 2.5 hours. After baseline values were recorded, dogs were randomly assigned to receive either buprenorphine (16 μg/kg, IV) or isovolumetric 5% dextrose solution. All variables were then recorded at 15-minute intervals for 2.5 hours.

Results

During isoflurane anesthesia, buprenorphine administration caused significant (P < 0.05) reductions in diastolic arterial pressure, mean arterial pressure, systolic arterial pressure, cardiac index, and heart rate, whereas systemic vascular resistance increased significantly. During halothane anesthesia, buprenorphine administration caused significant decreases in heart rate, cardiac index, mean, systolic and diastolic arterial blood pressures, and stroke volume, whereas pulmonary arterial blood pressure and systemic vascular resistance increased significantly.

Conclusion

Although the changes seen were significant, they were not sufficiently large to be of clinical importance in healthy dogs. (Am J Vet Res 1997;58:1280–1284)
Use of a breath test to determine the fate of swallowed fluids in cattle
Authors: McLeay L M. , Carruthers V. R. , Neil P. G.
Published: January 2024

Objective

To investigate a [13C]octanoic acid breath test as a means of detecting reticular groove contraction in cattle.

Animals

19 adult dairy cows with fistulated rumen, 10 yearling bulls, and 6 yearling steers.

Procedure

Cows were given 200 mg of [13C]octanoic acid in the caudal portion of the rumen, reticulum, or omasum/abomasum through the reticulo-omasal orifice, or were given the same dose of label with a drench of water or sodium bicarbonate. Collected breath was analyzed for 13C in CO2 for up to 3 hours. Breath of yearlings was analyzed for 13C in CO2 over 20 minutes after drenching with 200 mg of [13C]octanoic acid with water or sodium chloride and after sucking 200 mg of [13C]octanoic acid with molasses and water.

Results

In cows, enrichment of 13C in breath CO2 peaked at 20 to 30 minutes after placement of [13C]octanoic acid through the orifice, compared with a lower peak at 60 and 90 minutes after placement in the reticulum and rumen, respectively. The maximal increase in enrichment after placement of [13C]octanoic acid in the reticulum did not overlap with the minimal increase when placed through the reticulo-omasal orifice. Enrichment values in cows after drenching were consistent with values obtained after direct placement of [13C]octanoic acid. In yearlings, the inclusion of sodium chloride in the drench greatly increased enrichment, compared with water, but enrichment was greatest after sucking of the molasses, water, and [13C]octanoic acid combination.

Conclusions and Clinical Relevance

This breath test provides a simple, repeatable, nonradioactive, and noninvasive means of detecting the fate of swallowed fluids in cattle, thus revealing the route taken of orally administered therapeutic agents or nutrients. (Am J Vet Res 1997;58:1314–1319)
Effect of congenitally acquired Neospora caninum infection on risk of abortion and subsequent abortions in dairy cattle
Authors: Thurmond Mark C. , Hietala Sharon K.
Published: January 2024

Objectives

To estimate the extent to which abortion risk in dairy cattle during subsequent pregnancies was associated with congenitally-acquired Neospora caninum infection and previous abortions.

Animals

468 Holstein cattle.

Procedure

Newborn heifer calves were tested for evidence of congenital infection attributable to N caninum and examined repeatedly until the completion of their second lactation for serologic status and evidence of abortion.

Results

Compared with noninfected cows, congenitally infected cows had a 7.4-fold higher risk of abortion during their initial pregnancy and a 1.7-fold higher risk of aborting the first pregnancy during their first lactation. During the first pregnancy of their second lactation, congenitally infected cows that had aborted previously had a 5.6-fold higher risk of abortion, compared with cows that had not previously aborted and that were seronegative. The fetal risk period for N caninum-associated death began sooner and extended later during the initial pregnancy, compared with subsequent pregnancies.

Conclusion

Congenitally acquired N caninum infection can cause a substantial number of abortions during the initial pregnancy of heifers, with abortion risk attributable to N caninum decreasing in subsequent pregnancies, possibly because of selective culling. Subsequent abortions can be expected in congenitally infected cows that have aborted previously. (Am J Vet Res 1997;58:1381–1385)
Pulmonary and neutrophil responses to priming effects of platelet-activating factor in pigs
Authors: Kruse-Elliott K. T.
Published: January 2024

Objective

To investigate whether platelet-activating factor (PAF) primes the porcine pulmonary response to lipopolysaccharide (LPS), and what effect PAF priming has on porcine neutrophil superoxide (SO) release.

Animals

8- to 10-week old pigs.

Procedures

After pigs were anesthetized with sodium pentobarbital and instrumented for standard cardiopulmonary hemodynamic measurements, they were randomly assigned to receive PAF (0.1 ng/kg of body weight/min, 0 to 2 hours) plus saline solution (2 to 6 hours), saline solution (0 to 2 hours) plus LPS (0.25 μg/kg/h, 2 to 6 hours), or PAF plus LPS. Cardiopulmonary variables were measured throughout the study. Neutrophils were isolated from saline- or PAF-treated pigs at 0 (baseline) and 2 hours, and the effect of in vivo PAF exposure on ex vivo phorbol myristate acetate (PMA)-induced SO release was measured. Additionally, neutrophils isolated from immune-naive pigs were primed in vitro for 10 minutes with 10 μM PAF, and PMA-induced SO release was measured.

Results

PAF infusion significantly enhanced the increase in mean pulmonary arterial pressure, pulmonary vascular resistance, and hypoxemia associated with LPS administration. The infusion increased ex vivo neutrophil SO release, and in vitro PAF exposure primed neutrophils for enhanced SO release that was inhibited by pretreatment of cells with indomethacin.

Conclusions

PAF primes the porcine pulmonary system for the response to LPS. It primes porcine neutrophils in vivo and in vitro for PMA-induced SO release, and in vitro priming is mediated by cyclooxygenase products of arachidonic acid metabolism.

Clinical Relevance

PAF may modulate the porcine inflammatory response by acting as a priming agent, making pigs more responsive to the negative effects of bacterial LPS. (Am J Vet Res 1997;58:1386–1391)
Enhancement of secretagogue-induced adrenocorticotropic hormone release from cultured sheep anterior pituitary cells by recombinant ovine interleukin 1
Authors: Kemppainen Robert J. , Behrend Ellen N.
Published: January 2024

Objective

To determine whether recombinant ovine interleukin (oIL)-1 or oIL-2 alters basal or hypothalamic peptide-induced secretion of ACTH from cultured sheep pituitary cells.

Animals

The pituitary gland was collected from castrated male sheep ranging from 0.5 to 1 year old.

Procedure

Cells were cultured for 3 to 5 days, then were treated with oIL for variable periods. Cells were washed and treated with the hypothalamic peptides corticotropin-releasing hormone (CRH) or arginine vasopressin (AVP) or both. Medium bathing the cells was collected and assayed for ACTH concentration.

Results

Ovine IL-1α and oIL-1β, but not oIL-2, increased the amount of ACTH released in response to CRH, AVP, and CRH and AVP combined. Both oIL were effective after 3, but not 18 or 24 hours of exposure. Treatment with oIL-1 did not affect basal release of ACTH. Exposure of cells to phorbol 12-myristate 13-acetate or calphostin C before treatment with oIL-1β inhibited the ability of the cytokine to augment ACTH release, suggesting a role for protein kinase C in the process.

Conclusions

Local concentration of oIL-1 in the sheep pituitary gland may have an important role in determining secretion of ACTH in response to CRH or AVP or both from the hypothalamus.

Clinical Relevance

The hypothalamic-pituitary-adrenocortical axis may be activated after immune challenge. The cytokine oIL-1 has been implicated as an important mediator in this process. The pituitary gland may be an important target for this effect. (Am J Vet Res 1998;59:107–110)
Effects of age and location on the biomechanical and biochemical properties of canine tracheal ring cartilage in dogs
Authors: Hamaide Annick , Arnoczky Steven P. , Ciarelli Michael J. , Gardner Keri
Published: January 2024

Objective

To evaluate effects of age (immature vs adult) and location along the trachea on the biomechanical properties (via a tensile stress relaxation test) and biochemical properties (water content and total proteoglycan content) of canine tracheal ring cartilage.

Sample population

Entire trachea from 8 immature and 8 adult dogs.

Procedure

A section of each tracheal ring from 8 immature dogs (6 months old) and 8 adult dogs (2 to 3 years old) was tested biomechanically (maximal stress, equilibrium stress, equilibrium modulus, and percentage of relaxation) and processed for biochemical analysis (water content and total proteoglycan content). Two rings from each trachea were prepared for histologic analysis (H&E or safranin-O staining).

Results

Biomechanical and biochemical parameters were not different between cervical and thoracic rings of either age group. Mean maximal stress, equilibrium stress, and equilibrium modulus were significantly higher for adult, compared with immature, dogs. However, percentage of relaxation for adult dogs was significantly lower. Tracheal rings of adult dogs had a significantly higher proteoglycan content and a significantly lower water content than did those of immature dogs. Water content and biomechanical parameters were significantly correlated, and proteoglycan content and biomechanical properties were significantly but weakly correlated. On histologic sectioning, a qualitative decrease in safranin-O staining in the rings of immature dogs also was observed.

Conclusions and Clinical Relevance

Biomechanical and biochemical properties of the canine tracheal ring cartilage are altered with age. However, location of the ring along the trachea did not affect these properties for either age group. Results lend support to the theory that proteoglycan content has some effect on tensile properties of tracheal rings and may explain increased compliance observed in rings from dogs with collapsed trachea. (Am J Vet Res 1998;59:18–22)
Efficacy of fenbendazole in the treatment of experimental Giardia infection in dogs
Authors: Zajac Anne M. , LaBranche Timothy P. , Donoghue Ann R. , Chu Teng-Chiao
Published: January 2024

Objective

To evaluate the efficacy of fenbendazole as a treatment for Giardia sp.

Animals

10 male and 10 female commercial-source Beagles.

Procedure

The experiment was conducted in 2 replicates. Dogs considered free of Giardia infection on the basis of results of 3 consecutive negative fecal examinations were experimentally infected with approximately 1,000 Giardia cysts isolated from dog feces. After verification of infection, the dogs were allocated to 2 groups (treated and untreated) and were housed in separate rooms. Treated dogs received 50 mg of fenbendazole/kg of body weight, PO, daily, for 3 days. After treatment on the third day, treated dogs were removed from their runs, shampooed, rinsed with disinfectant, and returned to disinfected runs. Fecal samples were collected from all dogs 12 times during the next 25 days.

Results

Giardia cysts were found in the feces of every untreated dog during all or part of the test period. Nine of 10 treated dogs did not have Giardia cysts in any fecal sample examined; the other dog had a positive result on a single sample in the third week after treatment.

Conclusion and Clinical Relevance

Fenbendazole, at the nematocidal label dosage, is an effective drug for treatment of Giardia infection in dogs. (Am J Vet Res 1998;59:61–63)
Accuracy of noninvasive oxyhemoglobin saturation, end-tidal carbon dioxide concentration, and blood pressure monitoring during experimentally induced hypoxemia, hypotension, or hypertension in anesthetized dogs
Authors: Grosenbaugh D. A. , Muir W. W.
Published: January 2024

Objective

To determine reliability of noninvasive methods of arterial oxyhemoglobin saturation (SpO2), end-tidal CO2 concentration (PEtCO2 and blood pressure (BP) determination during periods of hypoxemia and systemic arterial BP perturbations.

Animals

7 healthy, conditioned dogs weighing 19 to 22 kg.

Procedure

3 pulse oximeters, 2 capnometers, and 2 oscillometric BP monitors were used to measure oxygen-carrying capacity of the blood, heart rate, ventilatory status and arterial BP changes during hypoxemia, and altered arterial BP. Pulse oximeter-derived SpO2 and PEtCO2 were determined during rapidly induced plateaus of hypoxia (decreased fractional inspired oxygen concentration [FiO2) and altered systemic arterial BP. A lead-II ECG was used to monitor heart rate.

Results

Pulse oximetry provided an accurate assessment of fractional oxyhemoglobin saturation (SaO2) at SpO2 > 70%. As SaO2 decreased from 70%, the magnitude of the SpO2 error increased (20% error at SpO2 < 30%). The PEtCO2 was accurate at PaCO2, ranging from 30 to 55 ± 5 mm of Hg under all experimental conditions. When PaCO2 was > 55 mm of Hg, both capnometers produced values that were as much as 20 mm of Hg less than the corresponding PaCO2. Mean BP was least dependent on pulse wave quality, consistently underestimating mean arterial BP by approximately 10 mm of Hg.

Conclusions and Clinical Relevance

The pulse oximeters tested provided an accurate estimation of SaO2 at SpO2 > 70%. A PEtCO2 value > 55 mm of Hg may represent hypercapnia that is more profound than indicated. Systolic BP determinations were most accurate during hypotensive states and least accurate during hypertension. Diastolic BP measurements were generally more accurate during hypertension than normotension. Accuracy is not appreciably affected by hypotension resulting from vasodilation or blood loss. The tendency to underestimate systemic arterial BP should not interfere with trend detection during unstable clinical conditions. (Am J Vet Res 1998;59:205–212)
Ground reaction forces in Greyhounds with tibial nerve injury
Authors: Rumph Paul F. , Steiss Janet E.
Published: January 2024

Objectives

To measure ground reaction force variables during lameness resulting from impaired tibial nerve function and to determine whether these variables changed significantly as recovery progressed.

Animals

11 healthy Greyhounds of either sex, weighing between 22 and 39 kg.

Procedure

On 3 consecutive days before surgery, ground reaction forces were measured by force platform gait analysis at the trot. In dogs under general anesthesia, the left tibial nerve was crushed proximal to innervation of the gastrocnemius muscle. Gait analyses were repeated on days 8 to 10, 28 to 30, 43 to 45, 58 to 60, and 90 to 92 after surgery. Ground reaction force variables and stance time were compared among the 3-day clusters.

Results

10 days after surgery, all dogs had weight-bearing lameness attributed to paralysis of muscles in the caudal compartment of the crus. Nerve regeneration resulted in functional recovery within 3 months. Decreases in vertical force were significant 10 days after surgery; thereafter, changes reflected gradual return of load bearing, with the most marked improvement between 10 and 45 days. At 90 days, vertical force variables were within 3% of presurgical values. Stance time for the left hind limb was significantly longer at 10, 30, and 45 days after surgery and was seen in all dogs, but returned to within 1% of preoperative stance time at 90 days. The effect of tibial nerve dysfunction on braking or propulsive force was not significant.

Conclusions and Clinical Relevance

The significant changes in vertical ground reaction forces in hind limbs of dogs during lameness that resulted from impaired tibial nerve function are detectable, as is response during recovery, by use of force platform analysis. (Am J Vet Res 1998;59:375–378)