bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies of endotoxin-induced neutrophil migration in bovine teat tissues, using indium-111-labeled neutrophils and biopsies
Authors: Persson Karin , Sandgren Charlotte Hallén , Rodriguez-Martinez Heriberto
Published: January 2024

Neutrophil migration through bovine teat tissues into the teat cistern, after endotoxin infusion into the teat cistern, was determined in vivo by 2 experimental procedures, indium-111 labeling of blood neutrophils, and obtaining multiple biopsy specimens from the teat cistern tissues. In both experiments, the number of leukocytes in the teat cistern flushing samples was continuously measured.

A lag phase of approximately 1 hour was required between endotoxin infusion into the teat cistern and the first observed neutrophil accumulation in the teat tissues. The rate of neutrophil accumulation in the teat tissues was highest between postinfusion (pi) hours 1 and 2, and the accumulation process ceased after pi hour 3. Neutrophils migrated toward the epithelium, and intraepithelial neutrophils were observed beginning approximately 2 hours after infusion, which coincided with the first influx of cells into the teat cistern. The cell influx into the teat cistern increased continuously up to pi hour 3, peaked between pi hours 3 and 5, and was close to preinfusion value at pi hour 22.

Use of indium-111-labeled neutrophils in the study of the inflammatory process provides a reliable noninvasive method to quantify cell migration in vivo. Use of biopsies allows quantification of the number of cells in different tissue areas, but has the disadvantage of being invasive. These 2 procedures complement each other, and could be of use in future studies of the local inflammatory process.
Histologic features of the carotid artery trifurcation in Thoroughbreds
Authors: Nakamura Takashi , Kiryu Keiji , Machida Noboru , Iwata Tsuyoshi , Oikawa Masa-aki , Kaneko Mikihiro
Published: January 2024

The common, external, and internal carotid and occipital arteries were examined histologically at the trifurcation of the common carotid arteries in 13 Thoroughbred foals (0 to 30 days old) and 64 Thoroughbred adults (2 to 4 years old). Calcification in the media of the common carotid and external carotid arteries was observed in 3 of the 13 foals and in 30 of the 64 adult horses. Calcification resembled that seen in Mönckeberg's arteriosclerosis in human beings, the cause of which is unknown.
Dimethylnitrosamine-induced hepatotoxicosis in dogs as a model of progressive canine hepatic disease
Authors: Boothe D. M. , Jenkins W. L. , Green R. A. , Corrier D. E. , Cullen J. M. , Boothe H. W. , Weise D.
Published: January 2024

A model of toxin-induced progressive hepatitis is described in Beagles. The toxin, dimethylnitrosamine, was administered orally to 18 Beagles; 6 dogs comprised a control group. Clinical signs and laboratory test results were monitored as disease progressed and were used to determine the end point of disease. Following euthanasia, histologic lesions were scored and used to derive a total severity score for each dog. Severity scores were then used to allot the 18 dogs to 3 groups of hepatic disease, defined as mild, moderate, or severe. Changes in clinical laboratory test results, including tests of hepatic function, and clinical signs indicative of liver disease were described chronologically for all dogs. Group means of clinical laboratory test results and quantifiable clinical signs (eg, weight loss and ascitic fluid accumulation) were compared. This model offers several advantages, compared with other experimental models of canine hepatic disease. These include hepatospecificity, similarity to natural disease (eg, the development of multiple extrahepatic portosystemic shunts), and the ability to titrate the disease to a desired end point. The major disadvantages of this model were the toxic nature of the drug to human beings and the variation in individual animal response to the toxin, which precludes preassignment of animals into groups.
Polypeptides associated with Pasteurella multocida infection in rabbits
Authors: Zimmerman Thomas E. , Deeb Barbara J. , DiGiacomo Ronald F.
Published: January 2024

Polypeptides from whole cell preparations of Pasteurella multocida serotypes A: 12 and A:3 were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred to nitrocellulose paper. Antigens were detected by immunoblot analysis, using sera from 3 groups of rabbits. Sera were obtained from rabbits inoculated intranasally with P multocida serotype A: 12 or A:3, from rabbits maintained in a rabbitry with enzootic P multocida A: 12 infection, and from rabbits maintained in a rabbitry with enzootic P multocida A:3 infection. Immunoblot analyses of pre- and postinoculation sera from experimentally infected rabbits, using serotype A: 12 antigen, revealed 3 polypeptides with approximate molecular mass of 28, 30, and 37 kDa that consistently detected antibodies after P multocida-induced infection. Sera from rabbits naturally infected with either serotype, tested against serotype A: 12 and A:3 antigens, detected the same polypeptides in both serotypes. Thus, immunologic reactivity to these polypeptides may be useful for serologic detection of P multocida infection.
Myoelectric activity of the small intestine in enterotoxin-induced diarrhea of calves
Authors: Roussel A. J. , Woode G. N. , Waldron R. C. , Sriranganathan N. , Jones M. K.
Published: January 2024

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

These findings are suggestive that enterotoxin-induced diarrhea of calves is accompanied by increased total spiking activity and minute rhythms in the distal portion of the jejunum and ileum.
Effects of fluoride on secretory and postsecretory phases of enamel formation in sheep molars
Authors: Milhaud Guy E. , Charles Eliane , Loubiàre Marie-Laure , Kolf-Clauw Martine , Joubert Christophe
Published: January 2024

Effect of fluoride was assessed on molars during and after mineralization. Two groups of 7 sheep each were dosed orally with 3.5 mg of fluoride/kg of body weight daily for 4 months (from 5 to 9 months after birth). Sheep of the first group were slaughtered immediately after fluoride administration; those of the second group were slaughtered 4 months later at the age of 13 months. Three control groups of 7 sheep each were slaughtered at 5 months (to determine the state of the teeth at the beginning of fluoride administration), and at 9 and 13 months.

During fluoride administration, plasma fluoride concentration rapidly increased to about 0.50 μg/ml; after fluoride administration, it stabilized at 0.20 μg/ml in treated sheep, whereas controls had concentration of 0.10 μg/ml (P < 0.01).

Parts of the molars that were in the process of mineralization during fluoride administration (mainly second molars) had thinning enamel, with pits, mainly close to the apex, marked decrease in hardness throughout the layer (< 100 Vickers U, compared with 240 Vickers U), and fluoride accumulation twice as high as that in controls (1,000 to 2,500 mg/kg [dry weight]). Fluoride accumulation was higher in dentine (2,700 to 4,200 mg/kg), but hardness was less affected.

On parts of the molars that were already mineralized (mostly, the first molar), changes in the appearance of enamel and cementum, decreased hardness (less important than in teeth during mineralization) affecting outer enamel more than inner enamel, high fluoride concentration (4,000 to 5,500 mg/kg [dry weight]) in outer enamel extending over 200 (μm were observed. Thus, in sheep, fluoride has a substantial postsecretory effect that may be explained by a slower maturation phase of enamel in this species.

Because molar wear is correlated to enamel hardness (dentine at the occlusal surface has low resistance—30 Vickers U), abnormal abrasion of molar teeth that have mineralized before and during fluoride intakes can be observed.
Serum and skin concentrations after multiple-dose oral administration of trimethoprim-sulfadiazine in dogs
Authors: Pohlenz-Zertuche Heidy Ortiz , Brown Murray P. , Gronwall Ronald , Kunkle Gail A. , Merritt Kelly
Published: January 2024

Six healthy adult mixed breed dogs were each given 5 oral doses of trimethoprim (TMP)/sulfadiazine (sdz) at 2 dosage regimens: 5 mg of TMP/kg of body weight and 25 mg of SDZ/kg every 24 hours (experiment 1) and every 12 hours (experiment 2). Serum and skin concentrations of each drug were measured serially throughout each experiment and mean serum concentrations of tmp and sdz were determined for each drug for 24 hours (experiment 1) and 12 hours (experiment 2) after the last dose was given. In experiment 1, mean serum tmp concentration was 0.67 ± 0.02 μg/ml, and mean skin tmp concentration was 1.54 ± 0.40μg/g. Mean serum sdz concentration was 51.1 ± 12.2 μg/ml and mean skin sdz concentration was 59.3 ± 9.8 μg/g. In experiment 2, mean serum tmp concentration was 1.24 ± 0.35 μg/ml and mean skin tmp concentration was 3.03 ± 0.54 μg/g. Mean serum SDZ concentration was 51.6 ± 9.3 μg/ml and mean skin sdz concentration was 71.1 ± 8.2 μg/g. After the 5th oral dose in both experiments, mean concentration of tmp and sdz in serum and skin exceeded reported minimal inhibitory concentrations of tmp/sdz (≤ 0.25/4.75 μg/ml) for coaguase-positive Staphylococcus sp. It was concluded that therapeutically effective concentrations in serum and skin were achieved and maintained when using the manufacturer’s recommended dosage of 30 mg of tmp/sdz/kg (5 mg of TMP/kg and 25 mg of sdz/kg) every 24 hours.
Influence of body size on tibial nerve somatosensory evoked potentials in dogs
Authors: Poncelet Luc , Michaux Charles , Balligand Marc
Published: January 2024

Somatosensory evoked potentials in response to tibial nerve stimulation were recorded from the scalp of 31 clinically normal mixed-breed dogs. The latency and amplitude of a main positive potential (P18), recorded with a frontal electrode referenced to the nose, were measured in subjects with body length ranging from 316 to 962 mm. A linear relation to body size explained the variations in latency among dogs (r2= 0.81); the amplitude variations were explained in part by body size (r2= 0.44). Bilateral tibial nerve stimulation significantly (P<0.05) increased the amplitude of P18, but its latency was unaffected, compared with unilateral stimulation. Results of unilateral right and left tibial nerve stimulation were compared and were not different. Replacing acepromazine with xylazine as premedication before thiopental anesthesia did not influence the recordings.
Enhancement of lymphocyte function and interleukin 1β transcription by recombinant bovine interleukin 1β
Authors: Stabel Judith R. , Kehrli Marcus E. , Goff Jesse P.
Published: January 2024

Six nonpregnant, nonlactating Jersey cows, averaging 4 to 6 years old, were used to evaluate the immunomodulatory effects of recombinant bovine interleukin 1β (rBoIL-1β). Cows were given 166 ng of rBoIL-1β/kg of body weight at 8-hour intervals for 96 hours. Persistent leukocytosis was observed within 3 hours of rBoIL-1 treatment, peaking 24 hours after the first IL-1β injection and returning to baseline values within 72 hours after cessation of IL-1β treatment. Injection of cows with rBoIL-1β stimulated lymphocyte blastogenesis and mitochondrial methyl-thiazoltetrazolium cleavage activity in resting cell cultures. Increases in the aforementioned lymphocyte activities were also observed in stimulated blood mononuclear cell cultures during IL-1β administration. Change in IgM production in cell cultures was not observed during IL-1β treatment. Within 24 hours of the first IL-1β injection, IL-1β mRNA transcription in stimulated blood mononuclear cell cultures was markedly increased, suggesting that IL-1β upregulates its own production in mononuclear cells. These data provide evidence that administration of cytokines, such as rBoIL-1β, enhances immune cell function and, therefore, may be useful in alleviating immunosuppression in cattle.
Effect of 4-bromo-calcium ionophore A23187 on release of Anaplasma marginale from bovine erythrocytes in vitro
Authors: Blouin Edmour E. , Blankemeyer James T. , Kocan Katherine M. , Ewing S. A.
Published: January 2024

The ionophore A23187 was used to facilitate release and continued development of Anaplasma marginale in short-term erythrocyte cultures. Addition of 10 μM A23187 to the cultures resulted in significant decrease in percentage of parasitized erythrocytes (ppe) by 24 hours after treatment; further development and increase in PPE was not observed. In contrast, the ppe of untreated cultures, those treated with dimethyl sulfoxide (dmso) only and with 1 μM A23187 increased slightly during that time. Total erythrocyte count decreased in treated cultures in excess of that expected after samples of the medium were taken for analysis. The greatest cell loss and increased hemoglobin concentration in culture medium was observed in cultures treated with 10 μM A23187 and with an equivalent volume of dmso. The dmso appeared to cause hemolysis of some erythrocytes, but not of infected cells selectively. Release of A marginale inclusion bodies was seen by electron microscopy in samples from the 10 μM A23187-exposed cultures. At 30 minutes after treatment, free initial bodies were frequently seen. Inclusion body membranes and individual A marginale were associated with membranes of adjacent erythrocytes. Individual rickettsiae were seen in cell depressions and appeared to be entering erythrocytes. However, neither further invasion nor development of the parasite in erythrocytes was observed. Ionophore A23187 appeared to promote release of A marginale from erythrocytes, but did not enhance infection of erythrocytes or development of organisms in vitro.
Cardiovascular responses to exogenous platelet-activating factor (PAF) in anesthetized ponies, and the effects of a PAF antagonist, WEB 2086
Authors: Wilson D. V. , Eberhart S. W. , Robinson N. E. , Rice R. , Gray P. R.
Published: January 2024

The effects of exogenous platelet-activating factor (paf) were determined in anesthetized ponies. Administration of paf induced a decrease in cardiac index that resulted in systemic hypotension. This was followed by tachycardia, hypertension, and a return of cardiac index to baseline. Pulmonary aterial pressure increased markedly because of pulmonary vasoconstriction. Exogenous paf also caused leukopenia and thrombocytopenia. The specific PAP receptor antagonist (WEB 2086) blocked all paf-induced changes. Flunixin meglumine, a cyclooxygenase inhibitor, abolished the pulmonary hypertension and tachycardia, and attenuated the systemic hypotension but did not change the paf-induced peripheral cellular changes. The paf antagonist also inhibited platelet aggregation induced by paf in vitro. The paf-induced changes are similar to those reported after endotoxin exposure in horses.
Effect of a specific platelet-activating factor antagonist on cardiovascular and peripheral cellular responses to colonic ischemia and reperfusion in anesthetized ponies
Authors: Wilson D. V. , Stick J. A.
Published: January 2024

The role of platelet-activating factor in mediating the cardiovascular and peripheral cellular responses to large-colon ischemia and reperfusion, was explored in anesthetized ponies. A specific platelet-activating factor (PAF) antagonist (WEB 2086) was administered to a group of 6 ponies, and another 6 ponies (controls) were given an equivalent volume of saline solution, prior to 1 hour of large-colon torsion. After correction of the torsion, ponies were monitored during the reperfusion period. Significant (P < 0.05) hypotension and metabolic acidosis developed in all ponies after correction of colonic torsion, cardiac index increased initially, but then decreased significantly (P < 0.05) over the study period. Mean times between correction of torsion and onset of cardiac failure and death were not different between groups. Significant (P < 0.05) thrombocytopenia developed during the reperfusion period in control ponies, but not in WEB-treated ponies. Blood leukocyte concentration in control ponies was more variable and significantly (P < 0.05) decreased immediately upon reperfusion, compared with that in WEB-treated ponies. We conclude that although the cardiovascular responses to colonic ischemia and reperfusion are not prevented by use of a specific paf-antagonist, specific peripheral cellular responses are mediated by paf.
Expression of calbindin-D28k in developing and growing ovaries of chicken embryos
Authors: Inpanbutr N. , Taylor A. N.
Published: January 2024

Immunoreactivity for 28 kd vitamin D-dependent calcium-binding protein (calbindin-D28k) has been localized in the germinal epithelium and cells surrounding oogonia and oocytes (future granulosa cells) of developing and growing ovaries of chicken embryos. The protein first appeared prominently in the germinal epithelium of the developing left ovary in 8-day embryos. At the twelfth day of incubation, cells surrounding oogonia and oocytes reacted intensely for calbindin-D28k. The number and intensity of calbindin-D28k-containing cells increased in both types of cells as the embryos further developed. Calbindin-D28k remained in the germinal epithelium throughout the study period observed (up to 10 weeks). However, the protein was present transiently in the future granulosa cells. It gradually decreased after hatching, and was virtually absent from granulosa cells in a 10-week old chicken. Compared with the known process of onset of sexual development, these results indicated possible involvement of calbindin-D28k in the early phases of oogenesis in chicken ovaries.
Correlations between histologic endometrial lesions in mares and clinical response to intrauterine exposure with Streptococcus zooepidemicus
Authors: Troedsson Mats H. T. , deMoraes Marcos J. , Liu Irwin K. M.
Published: January 2024

The relationship between histologic lesions in endometrial biopsy specimens and susceptibility to chronic uterine infection (cui) in mares was investigated. Mares were allotted to 4 groups on the basis of degree of endometrial lesions. Mares in group 1 (n = 6) had no pathologic changes, mares in group 2 (n = 5) had only mild pathologic changes, group-3 mares (n = 7) had moderate changes, and group-4 mares (n = 7) had severe inflammatory and fibrotic endometrial changes. Susceptibility to cui was determined by the inflammatory response to intrauterine inoculation of 5 × 106 Streptococcus zooepidemicus. The inoculum was given on the third day of behavioral estrus and in the presence of a follicle > 30 mm. Mares with > 1 neutrophil/5 high-magnification (400 ×) microscopic fields and > 20 colonies of S zooepidemicus at 96 hours after inoculation were considered to be susceptible to cui.

There was a significant association between biopsy grade and susceptibility to cui among the groups. Histologically normal endometrium was associated with resistance to cui, and severe histopathologic changes in the endometrium were associated with susceptibility to cui. Mild to moderate endometrial lesions did not correlate consistently with susceptibility or resistance to cui.
Development of a DNA probe for identification of bovine herpesvirus 4
Authors: Galik P. K. , van Santen V. L. , Stringfellow D. A. , Bird R. C. , Wright J. C. , Smith P. C.
Published: January 2024

A sensitive and specific dna probe for detection and identification of bovine herpesvirus 4 (bhv-4) was developed. Cloned fragments from a library of HindIII fragments of the bhv-4 (DN-599) genome were labeled with 32P or digoxigenin and were tested for sentitivity and specificity in detecting viral dna by dot-blot hybridization. Two probes were identified that detected 10 pg of purified viral dna, and detected viral dna in 0.001 μg of total dna extracted from bhv-4-infected cells. Both probes labeled with 32P and 1 labeled with digoxigenin detected viral dna in samples prepared from cells infected with 2 prototype strains (DN-599 and Movar 33/63) and 4 field isolates of bhv-4. The dna probes did not hybridize to total dna prepared from uninfected bovine cells or from cells infected with bhv-1, bhv-2, alcelaphine herpesvirus 1, pseudorabies virus, or equine herpesvirus 1. One probe, labeled with digoxigenin, was tested further by dot-blot hybridization with infected cell lysates that were simply treated with sodium dodecyl sulfate and proteinase K prior to application to the membrane, avoiding extensive dna purification procedures. This simplified procedure also resulted in specific detection of field isolates of bhv-4 and prototype strains of bhv-4.
Ultrastructural hepatocellular features associated with severe hepatic lipidosis in cats
Authors: Center S. A. , Guida L. , Zanelli M. J. , Dougherty E. , Cummings J. , King J.
Published: January 2024

In this study, we compared hepatic ultrastructure in healthy cats, in cats with severe hepatic lipidosis, and in cats with experimentally induced, chronic, extrahepatic bile duct occlusion. Ultrastructural features unique to the lipidosis syndrome included an apparent reduction in number of peroxisomes and alteration in their morphologic features. The quantity of endoplasmic reticulum, Golgi complexes, and lysosomes was subjectively reduced, and paucity of cytosolic glycogen was observed. Bile canaliculi appeared collapsed because of cytosolic distention with lipid. Mitochondria were reduced in number and were markedly pleomorphic. Cristae assumed a variety of shapes, lengths, and orientations. Ultrastructural features of bile duct occlusion were similar to those described in other species and differed from those in cats with hepatic lipidosis.
Isolation of an inhibitor of tumor necrosis factor-α-mediated cytotoxicity liberated from chemotaxin-stimulated equine white blood cell populations
Authors: Coyne C. P. , Fenwick Brad W. , Iandola John , Williams David , Griffith Gary
Published: January 2024

Objectives of this investigation were to extract and isolate protein fractions inhibitory to the cytotoxic properties of tumor necrosis factor-α (tnf-α). In this context, mixed populations of wbc were harvested from equine blood and were stimulated with a combination of a synthetic chemotactic peptide and a calcium ionophore. Several methods were subsequently applied for the initial preparation of cell-free crude protein extracts, including fractional precipitation with gradient concentrations of ammonium sulfate and preparative-scale isoelectric focusing. In addition, protein fractions were harvested from extracts of concentrated equine urine. Protein extracts of urinary origin were further separated by gel-filtration column chromatography.

Identification of protein fractions possessing properties inhibitory to the cytotoxic characteristics of tnf-α was facilitated by a tissue culture-based technique for the biological assay of tnf-α-mediated cytotoxicity. Purified protein extracts possessed a marked ability to inhibit or neutralize the cytotoxic properties of tnf-α, on the basis of survival of murine fibrosarcoma cell populations, compared with appropriate negative and positive reference controls. Relative purity of inhibitors and estimation of approximate molecular weight were established by conventional reducing and nonreducing sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis. Equine inhibitory protein fractions from mixed wbc populations, purified in the manner described, had molecular weights of 70,000 to 80,000 and 28,000. An analogous protein fraction of 28 kDa also was isolated from equine concentrated urine. Estimated isoelectric point of tnf-α inhibitor protein fractions was between pH of 5.5 and 6.1. These physical characteristics of equine tnf-α inhibitor protein fractions were similar to those described for a membrane-associated tnf-α receptor protein shed from chemotaxin- and calcium-ionophor-stimulated human wbc populations.
Immunologic changes in Ostertagia ostertagi-infected calves treated strategically with an anthelmintic
Authors: Yang C. , Gibbs H. C. , Xiao L.
Published: January 2024

Immunomodulation by Ostertagia ostertagi and the effects of strategic anthelmintic treatments were studied in 3 groups of 6 calves each: an infected group, inoculated with 100,000 third-stage larvae (L3)/calf at 1 and 28 days; an infected-treated group, similarly inoculated, but treated with ivermectin 9 days after each inoculation; and a noninfected control group. Calves were grazed on 2 previously clean pastures, with the infected and infected-treated calves sharing 1 pasture. All calves were inoculated at 12 weeks with Brucella abortus and infectious bovine rhinotracheitis vaccines, and at 13 weeks with a soluble O ostertagi L3 extract (sle). Infected and infected-treated calves had lower blood lymphocyte responses to phytohemagglutinin than did control calves at 2, 4, and 14 weeks, whereas the infected calves had higher responses at 6 and 8 weeks (P < 0.05). Responses to pokeweed mitogen followed a similar pattern, whereas those to sle were low in all calves. Infected and infected-treated calves had increased values of IgG1 to excretory-secretory antigens of L4 larvae, but no changes in the values of IgG1 to sle. They also had lower values of IgG and IgM to B abortus and antibodies to infectious bovine rhinotracheitis at 13 weeks. The infected-treated calves, however, had higher blood lymphocyte and monocyte counts and lower eosinophil count than did infected calves. They also had reduced abomasal mucosa thickness, abomasal wall weight, and abomasal lymph node weight than infected calves. It was concluded that O ostertagi causes nonspecific suppression of cellular and humoral immunity, hypersensitivity reactions coexisted with immunosuppression, and strategic anthelmintic treatments attenuated hypersensitivity reactions and initiated better immune responses.
Platelet, antithrombin, and fibrinolytic activities in taurine-deficient and taurine-replete cats
Authors: Welles Elizabeth G. , Boudreaux Mary K. , Tyler Jeffrey W.
Published: January 2024

Cats with cardiomyopathy, especially dilated cardiomyopathy associated with taurine deficiency, often develop systemic thrombi. To investigate the relation of taurine deficiency to formation and persistence of thrombi, cats were made taurine-deficient by consumption of a casein-based taurine-deficient diet, then were evaluated for anticoagulant and profibrinolytic activities and platelet function. The cats served as their own controls in the taurine-replete state; then, values were compared for the taurine-deficient state. Plasma (P < 0.01), blood (P < 0.05), and platelet (P < 0.05) taurine concentrations were decreased markedly after cats consumed the taurine-deficient diet for 6 weeks, compared with baseline concentrations before diet. Compared with the taurine-replete state, taurine deficiency induced significantly (P < 0.05) increased mean antithrombin III activity, no significant change in plasminogen and fibrinolytic activities, and similar clot retraction/lysis test results. Decreased (P < 0.01) adenosine diphosphate (adp)-induced platelet aggregation and [14C]serotonin release, and slightly increased (P < 0.05) collagen-induced platelet [14C]serotonin release, but unchanged collagen-induced platelet aggregation were observed in taurine-deficient cats, compared with taurine-replete cats.

Changes in antithrombin III activity most likely reflected hepatocellular acute-phase reaction, which indicates that taurine deficiency may induce a stress-responsive state. Results of platelet function testing indicate that taurine may modulate platelet responsiveness to physiologic agonists, but not in consistent manner. That platelets from the taurine-deficient cats had decreased responsiveness to adp, but increased responsiveness to collagen is surprising, because irreversible aggregation is mediated by release of granule-associated ADP after sufficient initial stimulus.

All cats had normal clot retraction in dilute blood, which indicated adequate platelet numbers and function; however, clots failed to lyse in vitro. To the authors knowledge, this observation, at present, lacks adequate explanation.

Development of marked taurine deficiency and altered in vitro results of anticoagulant activities and some platelet function tests did not result in clinical manifestations in our cats. Results of our study do not conclusively document a pathophysiologic role of taurine depletion in the formation or persistence of thrombi.
Transmission of proliferative enteritis to swine by use of embryonating chicken eggs
Authors: Jones Gary F. , Ward Gilbert E. , Collins James E. , Gebhart Connie J.
Published: January 2024

Embryonating eggs were inoculated with filtered porcine ileal mucosa containing intracellular curved rods (icr) and incubated for 4 to 6 days. Three of 12 pigs given the eggs per os developed microscopic lesions of proliferative enteritis (pe). Nonchallenge-exposed control pigs did not develop lesions of pe. Four of six positive control pigs given ileal mucosa from pigs with pe also developed microscopic lesions of pe. All of the PE lesions were found in pigs necropsied 10 to 29 days after challenge exposure. None of the swine in the study had clinical signs or gross lesions of pe.

Campylobacter spp were isolated from pigs with and without exposure to the ileal mucosa from pigs with pe. There was no relationship between Campylobacter spp isolation and development of lesions.

Deoxyribonucleic acids extracted from embryonating chicken eggs injected with the equivalent of 0.5 mg of mucosal lesions and incubated for 4 days hybridized to a dna probe specific for the icr, whereas dna extracted from 1.5 mg of mucosal homogenates of the same proliferative tissue did not hybridize with the same probe. Results of these experiments indicated that icr injected into eggs remained infective for pigs and suggest replication of icr in the first-passage eggs.
Growth and reproductive performance, during exposure to ammonia, of gilts afflicted with pneumonia and atrophic rhinitis
Authors: Diekman M. A. , Scheidt A. B. , Sutton A. L. , Green M. L. , Clapper J. A. , Kelly D. T. , Van Alstine W. G.
Published: January 2024

From 2 to 4.5 months of age, 80 crossbred gilts were reared in a conventional grower unit where they were naturally exposed to mycoplasmal and bacterial pathogens that cause pneumonia and atrophic rhinitis. At 4.5 months of age, gilts were moved to environmentally regulated rooms (4.9 × 7.3 m) and assigned at random to 1 of 2 treatment groups: low aerial concentration of ammonia (4 to 12 ppm; mean, 7 ppm) or moderate aerial concentration of ammonia (26 to 45 ppm, mean, 35 ppm).

Low concentration of ammonia was obtained by flushing of manure pits weekly, whereas moderate concentration of ammonia was maintained by adding anhydrous ammonia to manure pits that were not flushed. Gilts were weighed biweekly. Mean daily gain (mdg) was less (P < 0.01) for gilts exposed to moderate concentration of ammonia than for gilts exposed to low concentration of ammonia after 2 weeks in their respective environments. By 4 and 6 weeks, however, mdg was similar between the 2 treatment groups.

After 6 weeks in these environments, 20 gilts from each treatment group were slaughtered, and prevalence and severity of lung lesions and snout grades were determined. At slaughter, body weight was greater (P < 0.01) in gilts exposed to low, rather than moderate, ammonia concentration (94.5 vs 86.8 kg; sem, 3.3 kg). Percentage of lung tissue containing lesions (18 vs 12) and snout grade (2.8 vs 3.1) were similar between gilts exposed to low or moderate concentration of ammonia.

The remaining 20 gilts in each treatment group were maintained in their respective environments, exposed daily to mature boars and bred at first estrus. Age at puberty was similar between gilts exposed to low or moderate concentration of ammonia (208 vs 205 days; sem, 1.3 days), even though weight at puberty was less (P < 0.03) for gilts exposed to low concentration of ammonia than for gilts exposed to moderate concentration of ammonia (109.7 vs 118.2 kg; sem, 4.5 kg). At day 30 of gestation, number of live fetuses (10.6 vs 11.7), fetal length (2.53 vs 2.57 cm), and fetus-to-corpus luteum ratio (0.85 vs 0.78) were similar between gilts at low and moderate ammonia environments. These data indicate that exposure of gilts to mean aerial ammonia concentration of 35 ppm in environmentally regulated rooms depressed mdg for 2 weeks, but failed to alter onset of puberty or litter size at day 30 of gestation.
Pharmacokinetics of phenolsulfonphthalein in sheep
Authors: Danielson Terry J. , Taylor Wesley G.
Published: January 2024

Pharmacokinetic variables of phenolsulfonphthalein (psp) were determined in sheep after rapid iv injection and iv infusion to steady state. In Suffolk wethers, an average of < 75% of an iv administered dose was eliminated in urine, indicating that measures of systemic clearance overestimate renal clearance in this species. Furthermore, psp elimination from plasma was more rapid in Suffolk than Rambouillet wethers and, in Suffolk ewes, systemic clearance decreased from mean ± sd 7.8 ± 0.3 ml/min/kg of body weight to 4.7 ± 1.1 ml/min/kg at steady-state plasma concentration of 2.4 ± 0.3 and 151.3 ± 31.8 μg/ml, respectively. These observations indicate that, similar to that in other species, systemic clearance of psp in sheep is concentration-dependent and that significant differences may exist between breeds.
Abomasal and duodenal motility in yearling cattle after administration of prokinetic drugs
Authors: Roussel A. J. , Brumbaugh G. W. , Waldron R. C. , Baird A. N.
Published: January 2024

Effects of the following treatments on abomasal and duodenal myoelectric activity in yearling cattle were studied: 2 ml of 0.9% sodium chloride solution (nacl); 0.07 mg of bethanechol (bet)/kg of body weight; 0.1 mg of metoclopramide (met)/kg; and 0.07 mg of bethanechol and 0.1 mg of metoclopramide (betmet)/kg. All treatments were administered SC during the early part of phase I of the migrating myoelectric complex. Myoelectric signals were recorded for 4 hours after administration of the treatments from 1 electrode in the antrum and 3 electrodes in the duodenum.

For the antral spike rate (asr), there was no significant difference among treatments during the first hour, but the asr was significantly (P < 0.05) greater during hours 2 to 4 after treatment with betmet, compared with asr. for met alone. The duodenal spike rate (dsr) was significantly (P < 0.05) greater during the first hour after administration of betmet than after the other treatments. After administration of BET, DSR was significantly (P < 0.05) greater than after met or nacl. There was no difference in dsr after met, compared with dsr after nacl. There was no significant difference in dsr among treatments during the second and third hours. The total antegrade propagating spike (tatp) count was greater after administration of betmet in all hours, compared with the other treatments. The ratio of taps to total spikes on the orad-most duodenal electrode was significantly (P < 0.05) greater after betmet during hours 1 and 2.
Ultrasonographic examination of the ventral neck region in cows
Authors: Braun Ueli , Föhn Josef , Pusterla Nicola
Published: January 2024

The position, dimensions, and structure of the thyroid gland, the portion of the esophagus in the neck, the cervical lymph nodes, and the major blood vessels of the neck were determined via ultrasonography in cattle. The left and right ventral neck regions of 30 healthy Swiss Braunvieh cows were examined ultrasonographically, using 3.5- and 5.0-MHz linear transducers and a 3.5-MHz convex transducer.

The external jugular vein was situated directly beneath the skin in the upper and middle parts of the neck and 2.7 to 6.6 cm from the body surface in the lower part of the neck. In contrast, the common carotid artery was located further from the body surface along the entire ventral neck region; depending on the measuring point, this distance varied from 2.6 to 10.9 cm. The external jugular vein narrowed from caudad to craniad. The diameter of the common carotid artery remained fairly constant along its course in the ventral part of the neck and varied from 0.9 to 1.4 cm.

The thyroid gland was identified via ultrasonography caudodorsal to the larynx. It appeared as an echogenic spindle-shaped structure with finely granular echogenic pattern.

The esophagus appeared as a band-shaped structure in longitudinal section, and it could be followed to the thoracic inlet. Its width increased from craniad to caudad, and mean ± SD diameter was 2.9 ± 0.23 cm.

The medulla, hilus, cortex, and capsule of the cervical lymph nodes could be clearly differentiated via ultrasonography. Mean length and width of the left cervical lymph node were 3.0 ± 0.45 and 1.8 ± 0.23 cm, respectively.

To determine reproducibility and reliability of the results, 10 cows were examined by ultrasonography 10 times within 2 weeks. The interassay coefficients of variation determined from these examinations varied from 3.0 to 12.3%; most of the coefficients of variation ranged from 5 to 10%. The smallest coefficients of variation were determined for diameter of the common carotid artery, and the largest were for diameter of the external jugular vein.

Description of the ultrasonographic appearance of the structures of the ventral neck region in healthy cattle represents the basis for use of diagnostic ultrasonography in cattle with suspected diseases involving this area. The technique is noninvasive and can be performed on cattle in standing position.
Effects of echinocytosis on hermorrheologic values and exercise performance in horses
Authors: Weiss Douglas J. , Geor Raymond J. , Smith Clark M.
Published: January 2024

Effects of echinocytosis on blood rheology and exercise performance were evaluated for 5 Thoroughbreds. Echinocytosis was induced by administration of furosemide (1 mg/kg of body weight, im, q 12 h) for 4 days. Furosemide treatment resulted in decreases in serum sodium and serum chloride concentrations and in RBC chloride and potassium concentrations. Echinocytosis was associated with increased rbc density as determined by rbc density gradient centrifugation. However, samples containing echinocytes were more filterable than control samples, indicating that echinocytes were not rigid cells. Erythrocyte sedimentation rate was decreased in blood samples containing echinocytes, indicating that cell-to-cell interaction was reduced. Whole blood viscosity was not altered by presence of echinocytes. Echinocytes did not impair the capacity of horses to complete treadmill exercise tests, nor did they alter heart rate or blood gas variables. However, plasma lactate concentration was higher in samples obtained during exercise at a treadmill speed of 9 m/s. Echinocytosis was associated with higher postrace creatine kinase activity. These data indicate that echinocytes may be dense, but not rigid cells, which have decreased tendency to aggregate and do not increase whole blood viscosity. Therefore, echinocytes are unlikely to inhibit or obstruct microvascular blood flow.
Acute effect of hydralazine administration on pulmonary artery hemodynamics in dogs with chronic heartworm disease
Authors: Atkins Clarke E. , Keene Bruce W. , McGuirk Sheila M. , Sato Takashi
Published: January 2024

In an effort to better understand the role of vasodilators in the management of pulmonary hypertension associated with chronic heartworm disease (hwd), pulmonary hemodynamic measurements were obtained from 7 experimentally infected, anesthetized dogs before and after hydralazine administration (mean dose, 1.96 mg/kg of body weight). Five dogs were maintained on room air, while 2 were maintained on 100% oxygen during the hydralazine study. The hemodynamic effect of hydralazine in dogs with hwd was evaluated, using heart rate, cardiac index, mean pulmonary artery pressure, mean arterial pressure, total pulmonary resistance, total systemic resistance, total systemic resistance/total pulmonary resistance, left ventricular dP/dtmax, left ventricular end diastolic pressure, and left and right ventricular double products ([mean arterial pressure × heart rate] and [mean pulmonary artery pressure × heart rate], respectively). Responders were defined as those in which total pulmonary resistance decreased ≥ 20% without an increase in mean pulmonary arterial pressure and in which heart rate increase was ≤ 10%. Comparison was also made between maximal hemodynamic effect of hydralazine with that after 100% oxygen administration for 15 minutes to previously normoxemic dogs (n = 5). Significance was determined if P < 0.05, using the paired t-test.

Hydralazine induced significant reductions in mean pulmonary and systemic arterial pressures and total pulmonary resistance, with no significant change in heart rate, cardiac index, total systemic resistance, left ventricular dP/dtmax, left ventricular end diastolic pressure, or right and left ventricular double products. Four (57%) of the 7 dogs studied were considered responders. Pretreatment cardiac index, mean pulmonary artery pressure, and total pulmonary resistance did not allow differentiation of responders from nonresponders. However, pretreatment right ventricular end diastolic pressure was significandy less in responders than in nonresponders. Two dogs sustained hypotension after hydralazine administration, but no dogs had significant tachycardia. In dogs with experimentally induced hwd, treatment with hydralazine had significantly greater effect on cardiac index and mean pulmonary and systemic arterial pressures and resistance than did administration of 100% oxygen. These data indicate that further study of vasodilators for treatment of hwd-induced pulmonary hypertension may be warranted.
Use of a conductance catheter to assess the effect of endotoxemia on left ventricular end-systolic pressure-volume relationships in anesthetized swine
Authors: Hellyer Peter W.
Published: January 2024

Effects of endotoxemia on left ventricular contractility and systemic hemodynamics were determined in pentobarbital-anesthetized swine. A multielectrode conductance (volume) catheter and a high-fidelity pressure transducer catheter were passed retrograde into the left ventricle to continuously measure pressure and volume. End-systolic pressure-volume relationships were determined during transient (8 to 10 s) caudal vena caval balloon occlusion. Lactated Ringer's solution was administered at a rate sufficient to maintain left ventricular end-diastolic pressure ≥ 6 mm of Hg. Following baseline measurements, Escherichia coli endotoxin (055-B5) was infused iv at 2.5 μg/kg of body weight/h for 3 hours. Left ventricular end-systolic elastance (Ees), the slope of the end-systolic pressure-volume relationship; end-systolic elastance normalized for left ventricular end-diastolic volume (Ees norm); the rate of increase of left ventricular pressure (dP/dtmax); and preload recruitable stroke work (prsw, stroke work-to-end-diastolic volume relationship) did not change in endotoxemic swine, compared with baseline measurements or with values from control (physiologic saline solution-treated) swine. Left ventricular pressures and volumes had marked pig-to-pig variability in the control and endotoxin-treated groups. Determination of Ees, Ees norm, and prsw was further confounded by development of frequent premature ventricular contractions during caudal vena caval balloon occlusion. Endotoxin significantly (P < 0.05) decreased left ventricular end-diastolic pressure, compared with that in control swine, and significantly (P < 0.01) decreased left ventricular end-diastolic volume, compared with baseline. Endotoxin decreased cardiac index and arterial blood pressure, whereas heart rate, central venous pressure, and mean pulmonary arterial pressure increased. Endotoxin did not decrease myocardial contractility, as measured by Ees, Ees norm dP/dtmax, or prsw in anesthetized swine.
Evaluation of a single oral dose of lufenuron to control flea infestations in dogs
Authors: Hink W. F. , Zakson M. , Barnett S.
Published: January 2024

A single dose of lufenuron was administered to dogs to test its efficacy in controlling cat flea (Ctenocephalides felis) infestations for at least 30 days. Efficacy measurements revealed marked differences in the reproduction capability of fleas collected from dogs in the treatment vs the control group. Essentially, all of the eggs collected from dogs treated with lufenuron were unable to develop into normal adult fleas. Conversely, in the control group, 68.6% of the flea eggs developed into normal adult progeny.
Relation between body temperature and dexmedetomidine-induced minimum alveolar concentration and respiratory changes in isoflurane-anesthetized miniature swine
Authors: Vainio Outi M. , Bloor B. C.
Published: January 2024

Dexmedetomidine (dex), an α2-receptor agonist, is the pharmacologically active d-isomer of medetomidine, a compound used as a sedative in veterinary medicine. Isoflurane anesthetic requirement (minimum alveolar concentration; mac), rectal temperature, and cardiorespiratory variables were studied in chronically instrumented Yucatan miniature swine during dex (20 μg/kg of body weight)-induced changes in body temperature. All studies were performed at room temperature of 22 C. The dex was given as a 2-minute infusion into the left atrium. Each pig was studied twice. For protocol 1, the core temperature of the pigs was maintained at (mean ± SD) 38.2 ± 0.5 C by use of a thermostatically controlled water blanket and a heating lamp. For protocol 2, the core temperature was not externally manipulated and it decreased from 38.2 ± 0.4 C to 32.2 ± 1.2 C during the more than 3 hours of the protocol. Control isoflurane mac was 1.66 ± 0.2% and was 1.74 ± 0.3% for protocols 1 and 2, respectively; dex decreased mac by 34 and 44%, respectively. For protocol 1, reduction in mac after dex administration returned by 50 and 80% at 84 and 138 minutes, respectively. If rectal temperature was not maintained (eg, allowed to decrease), mac was reduced by 57% at the same time as the return to 80% in the swine with maintained body temperature. Respiratory rate and minute ventilation were significantly higher in swine with maintained temperature. The PaCO2, was lower and, accordingly, pH was higher in these swine. Blood pressure and heart rate were not affected by temperature changes.