bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Antimicrobial Susceptibility of Pseudomonas aeruginosa by Disk Diffusion and Microdilution Methods
Authors: Cox Hollis Utah , Luther D. Gene
Published: February 2025

Disk diffusion susceptibility tests were performed on 180 recent clinical isolates of Pseudomonas aeruginosa. Minimal inhibitory concentration values were determined at the same time by a broth microdilution method. All isolates were sensitive to colistin (< 4 μg/ml), but resistant to ampicillin (≥ 16 μg/ml), cephalothin (≥ 64 μg/ml), and nitrofurantoin (> 64 μg/ml). More than 90% of the isolates were sensitive to gentamicin (median, ≤ 0.25 μg/ml), tobramycin (median, ≤ 0.25 μg/ml), and amikacin (median, ≤ 1.0 μg/ml) and more than 70% were sensitive to carbenicillin (median, 64 μg/ml). When the resistant and intermediate categories were combined, over 90% of the isolates were resistant to tetracycline (median 16 μg/ml), chloramphenicol (median, > 32 μg/ml), kanamycin (median, 16 μg/ml), and trimethoprim-sulfonamide combination (median, 4 μg/ml; 76 μg/ml). Differences between the disk diffusion and microdilution methods in distinguishing resistant isolates of Ρ aeruginosa from sensitive isolates were minor. Complete agreement between the two methods was obtained in 87.0% of the observations.
Urine Concentrations of Chloramphenicol, Tetracycline, and Sulfisoxazole After Oral Administration to Healthy Adult Dogs
Authors: Ling Gerald V. , Conzelman Gaylord M. , Franti Charles E. , Ruby Annette L.
Published: February 2025

Chloramphenicol, tetracycline, and sulfisoxazole were administered (orally) in separate trials to clinically healthy adult dogs of both sexes at 8-hour intervals for five consecutive 8-hour test periods. All urine was collected from each dog during each test period and an aliquot from each period was assayed for antimicrobial activity.

Daily doses of the antimicrobics were as follows: chloramphenicol 99 mg/kg of body weight, tetracycline 55 mg/kg, and sulfisoxazole 66 mg/kg. Mean 8-hour urine concentrations (± 1 sd) for chloramphenicol were 124 ± 40 μg/ml; for tetracycline, 138 ± 65 μg/ml; and for sulfisoxazole, 1,466 ± 832 μg/ml. The mean 8-hour percentages of the doses of drug eliminated in active form in the urine were 6.3 ± 2.6% for chloramphenicol, 11.2 ± 2.0% for tetracycline, and 68.5 ± 2.1% for sulfisoxazole.
Lactic Acid and Glucose Metabolism in Healthy, Lactic Acid-Infused, and Diarrheic Calves
Authors: Case G. L. , Phillips R. W. , Cleek J. L.
Published: February 2025

Kinetics of glucose and lactate metabolism were measured in healthy (normal) calves, healthy calves infused with lactate, and in calves which had received an enteropathogenic coronavirus inoculum and had become diarrheic. Lactate utilization was positively correlated with blood lactate concentration in the healthy calves, but its turnover was markedly reduced in diarrheic animals. The decreased turnover was not due to inhibition of lactate oxidation, but appeared to relate to decreased gluconeogenesis. Glucose entry rate was not affected by diarrhea, but was a function of glucose concentration.
Caprine Toxoplasmosis: Abortion, Clinical Signs, and Distribution of Toxoplasma in Tissues of Goats Fed Toxoplasma gondii Oocysts
Authors: Dubey J. P. , Sharma S. P. , Lopes Carlos W. G. , Williams Jeffrey F. , Williams Christine S. F. , Weisbrode Steven E.
Published: February 2025

Thirteen goats (9 does and 4 bucks) were each inoculated orally with 10,000 infective Toxoplasma gondii oocysts. Three does and one buck were used as noninoculated controls. In 2 to 4 days after inoculation (dai), inoculated goats became dull, pyrectic (40 to 41 C), and anorectic. Three goats died (10, 10, and 14 dai) and two goats were killed (7 and 32 dai) because they were moribund; also, 3 does aborted, 2 had weak kids, and 2 had dead fetuses. Toxoplasma was isolated from the placenta of three goats, and the fetal tissues of four goats. The control goats remained asymptomatic.

The distribution of T gondii in blood and other tissues was studied by inoculation of mice with caprine tissues. Parasitemia was detected in 7 of 7 goats—beginning 4 dai in 1 goat, 5 dai in 5 goats, and 8 dai in 1 goat. The parasitemia lasted 3 to 10 days. Toxoplasma was isolated from the milk of 2 goats at 12 to 14 dai. Toxoplasma was isolated from 15 or more tissues of 5 goats killed 7 to 35 dai and from 10 tissues of 2 goats killed 69 and 95 dai.
Effects of Neomycin on the Waveform of Auditory-Evoked Brain Stem Potentials in Dogs
Authors: Morgan Joel L. , Coulter Dwight B. , Marshall Arvle E. , Goetsch Dennis D.
Published: February 2025

SUMMARY AND CONCLUSIONS

Neomycin sulfate was administered intravenously to eight mixed-breed dogs at a dosage of 30 mg/kg/day for as long as 50 days. Auditory-evoked brain stem potentials (aebp) were recorded from the dogs three times a week. The aebp amplitudes and latencies from the eight treated and the eight control dogs were compared.

All treated dogs eventually exhibited an isoelectric aebp. The time required for the aebp waveform loss to occur in the treated dogs varied between 22 and 50 days. The aebp waveforms were still isoelectric when measured as long as 150 days after neomycin administration was stopped. The fact that aebp did not return would tend to support the findings of others that the loss of the receptors in the inner ear, due to neomycin toxicity, is permanent.

The results of this electrophysiologic study indicate that the organ of Corti (organum spirale) is the site of pathologic changes in the auditory system that result from neomycin treatment.
Susceptibility of Nonhuman Primate Species to Infection by Simian Rotavirus SA-11
Authors: Soike K. F. , Gary G. W. , Gibson S.
Published: February 2025

Enzyme-linked immunosorbent assay examination of sera from three nonhuman primate species demonstrated the presence of antibody reacting with simian rotavirus SA-11 and calf rotavirus C486. The occurrence of this antibody in sera from adult, wild-caught animals suggests natural rotavirus infection. The occurrence of antibody was highest in the chimpanzee and declined, respectively, in the rhesus macaque and in the squirrel monkey.

Inoculation of three infant rhesus macaques, a nursery-reared chimpanzee, and a cesarian-derived nursery-reared baboon with SA-11 virus resulted in enteric infection, with virus excretion beginning 48 to 72 hours after oral administration of the virus. Clinical disease, as manifested by diarrhea, was observed only in the chimpanzee.

Inoculation of ten squirrel monkeys, from 30 to 191 days old, induced infection only in the monkey inoculated at 30 days of age. This monkey became ill within 48 hours after viral administration and was euthanatized. Necropsy demonstrated a generalized infection, with virus recovered from lung, liver, kidney, spleen, and intestine. The remaining nine inoculated squirrel monkeys failed to develop enteric infection and did not respond with antibody to SA-11 virus.
An Approach to the Anesthetic Requirements for a Chronic Animal Preparation
Authors: Bagshaw Roger J. , Cox Robert H.
Published: February 2025

The general anesthetic requirements for the preparation of a chronic experimental animal are discussed with respect to the implantation of an electromagnetic flow probe around the ascending aorta of the dog. After preanesthetic management and induction, several techniques for the maintenance of anesthesia are briefly considered. A technique is emphasized that combines a light general anesthetic with a regional nerve block and best fulfills the general anesthetic requirements.
Urine Concentrations of Five Penicillins Following Oral Administration to Normal Adult Dogs
Authors: Ling Gerald V. , Conzelman Gaylord M. , Franti Charles E. , Ruby Annette L.
Published: February 2025

Penicillin G, penicillin V, ampicillin, hetacillin, and amoxicillin were administered separately per os to clinically normal adult dogs of both sexes at 8-hour intervals for five consecutive 8-hour test periods. All urine was collected from each dog during each test period and was assayed for antimicrobial activity.

Daily doses of the antimicrobics used were as follows: penicillin G, 110,000 U/kg of body weight; penicillin V, 77 mg/kg; ampicillin, 77 mg/kg; hetacillin, 77 mg/kg; and amoxicillin, 33 mg/kg. Mean 8-hour urine concentrations (± 1 sd) were as follows: penicillin G, 294 ± 210 U/ml; penicillin V, 148 ± 98 μg/ml; ampicillin, 309 ± 55 μg/ml; hetacillin, 300 ± 156 μg/ml, and amoxicillin 201 ± 93 μg/ml. Among the three antimicrobials administered at the same daily dosage, penicillin V, ampicillin, and hetacillin, the mean urine concentrations of penicillin V were significantly lower (P < 0.01) than were concentrations of ampicillin and hetacillin. The mean urine concentrations of the latter two did not differ significantly (P > 0.05).
Electromagnetic Measurements of Metacarpal Blood Flow in Nonanesthetized Horses
Authors: Scott E. A. , Sandler G. A.
Published: February 2025

Blood flow (milliliter/minute) was measured in the medial palmar artery of 12 horses, using electromagnetic flow equipment. Extraluminal flow probes were surgically placed around the artery and base-line blood flows were recorded during surgical manipulation. After horses had recovered from anesthesia, blood flows were recorded each day for 11 days.

According to mean average blood flows, horses were allotted to two groups: group 1—those with predominately normal flow characteristics, and group 2—those horses with predominately abnormal flow features.

Average daily mean blood flows in the medial palmar artery () of group 1 horses were 103 ml/min (min-max, 10 to 210), and for group 2, 49 ml/min (min-max, 0 to 300).
Clostridium difficile-Associated Cecitis in Guinea Pigs Exposed to Penicillin
Authors: Lowe Bruce R. , Fox James G. , Bartlett John G.
Published: February 2025

Penicillin treatment resulted in lethal hemorrhagic cecitis in seven of eight guinea pigs. Cecal contents at necropsy from all seven animals contained a cytopathic toxin which was neutralized by Clostridium sordellii and C difficile antitoxins. Bacteriologic cultural examinations of these specimens yielded penicillin-sensitive strains of C difficile which produced a similar or identical cytotoxin in vitro. Stools obtained before penicillin administration and cecal contents from control animals lacked a cytotoxin and cultures failed to yield C difficile. Intracecal injection of cell-free supernatant of C difficile broth cultures reproduced the lesion noted with penicillin treatment. These results implicate C difficile as an agent of penicillin-induced lethal hemorrhagic cecitis in guinea pigs.
Pasteurella multocida: Antibody-Mediated Resistance to Virulent Challenge Exposure in Vaccinated Turkeys
Authors: Nathanson Robert M. , Hofstad M. S. , Jeska Edward L.
Published: February 2025

Aspects of antibody-mediated resistance to Pasteurella multocida infection in vaccinated turkeys were investigated. Pasteurella immune serum obtained from vaccinated turkeys was shown to confer temporary protection to nonvaccinated turkey poults. Recipients given immune serum were free of clinical signs of disease for at least 8 days after im challenge exposure with virulent Ρ multocida 1059. All turkeys given normal serum died within 36 hours of challenge exposure.

Vaccinated bursectomized turkeys were more susceptible to im challenge exposure than were vaccinated non-bursectomized turkeys. In two of three trials, mortality also occurred earlier in the bursectomized groups when compared with mortality in the control groups. The presence of specific antibody may be an important determinant in resistance to Pasteurella infection.
Histopathologic Evaluation of Livers of Pregnant Hamsters Infected with Leptospira canicola
Authors: Sapp W. J. , Siddique I. H. , Williams C. S. , Graham T.
Published: February 2025

Pregnant hamsters were inoculated with Leptospira canicola by an intraperitoneal route. Grossly, the livers were enlarged and pale yellow. On light microscopic examination, disruption of the hepatic cords, as well as granulation of hepatocyte cytoplasm, was evident.

On electron microscopic examination, the livers had evidence of severe cellular degradation as early as post-inoculation hour (pih) 24. At pih 96, pathologic changes were more pronounced. The rough endoplasmic reticulum was swollen and there was membrane disruption. These changes were not observed in the livers of control animals. In addition, livers of the fetuses at pih 72 exhibited severe degenerative changes.
Effect of Dietary Iodide on Hypophyseal and Thyroid Hormone Secretions in Holstein-Friesian Heifers
Authors: Leung K. , Convey E. Μ. , Conner G. H.
Published: February 2025

Our objective was to determine the effects of feeding supplemental iodide on development of the hypophysisthyroid axis in Holstein-Friesian heifers. Forty heifers, 11 to 15 weeks of age, were assigned to be fed 0, 50, 250, or 1,250 mg of iodide daily in the form of ethylenediamine dihydriodide for 162 days.

Daily weight gains of heifers fed 250 or 1,250 mg of supplemental iodide daily were less than for control heifers for 21 and 77 days, respectively, after onset of treatment. Thereafter, supplemental iodide had no effect on weight gain. Thyroidal weights, when adjusted for body weight differences, were greatest in heifers fed 1,250 mg of supplemental iodide daily, whereas hypophyseal and adrenal weights were unaffected by iodide feeding. In addition, total glucocorticoid concentrations in serum were similar among treatment groups.

Basal thyrotropin (thyroid-stimulating hormone; tsh) concentrations in serum of all heifers were not different throughout the treatment period, with the single exception of day 78 when tsh values for heifers fed 1,250 mg of iodide were higher than for controls. On the same day, concentrations of tri-iodothyronine (T3) and thyroxine (T4) in these heifers (1,250 mg) reached nadirs of 0.7 ng/ml and 27.4 ng/ml, respectively. Although concentrations of both thyroid hormones increased thereafter, they remained less than that of controls.

The tsh release after administration of thyrotropin-releasing hormone (trh) was greater in heifers fed 1,250 mg of supplemental iodide daily than that of controls beginning on day 22 of treatment and continuing throughout the entire iodide feeding period. However, the increases in serum T3 and T4 that occurred in response to the trh-induced release of tsh were not altered by treatment. Thus, the amount of tsh released after trh may have induced maximum release of thyroid hormone in all treatment groups.

Basal concentrations of T3 and T4 in heifers which were given 1,250 mg of iodide daily remained less than controls 10 days after the end of treatment. However, tsh responses to trh were no longer statistically different among groups.

Based on these observations, we conclude that supplemental iodide at quantities less than 250 mg daily (160 times the daily National Research Council requirement) does not affect development of the hypophysis-thyroid axis in growing dairy heifers.
Effects of Injectable Famphur on Young Brahman and Angus Cattle
Authors: Randell Wallace F. , Bradley Richard E.
Published: February 2025

Clinical responses were monitored in young Angus and Brahman bulls given im injections of an experimental solution of 35% famphur in a dose 5 times greater than the recommended dose (83.2 mg/kg). Five of the 6 treated Brahman bulls had severe clinical signs of organophosphorous toxicosis, and 4 died within 48 hours after they were dosed. Only 1 of the 5 treated Angus bulls showed clinical signs of toxicosis and it recovered.

In a subsequent trial, clinical and cholinesterase responses were monitored in young Brahman bulls, steers, and heifers given famphur at different dosages. Highly significant (P < 0.001) rbc cholinesterase inhibition over the 28-day trial was observed in animals given 16.6, 33.3, and 49.9 mg of the drug/kg. In comparison to Brahman heifers and steers, a lower treatment level of famphur (33.3 mg/kg) induced toxicosis in bulls. However, no significant differences in rbc or plasma cholinesterase inhibition were found to be due to treatment-sex interactions.
In Vitro Effect of Isoprinosine on Rabies Virus
Authors: Hernández-Jáuregui P. , González-Vega D. , Cruz-Lavín E. , Hernández-Baumgarten E.
Published: February 2025

The in vitro effect of isoprinosine, an antiviral compound, was evaluated on ERA and V319 rabies viral strains. Isoprinosine diminished the number of immunofluorescent cells, viral titers, and structures involved in rabies virus replication. Mechanism of antiviral action was probably mediated by modification of the polyribosome conformation and function.
Application of the Amplified Enzyme-Linked Immunosorbent Assay: Comparative Quantitation of Bovine Serum IgG1, IgG2, IgA, and IgM Antibodies
Authors: Butler J. E. , McGivern P. L. , Cantarero L. A. , Peterson L.
Published: February 2025

The comparative quantitation of serum antibodies to a defined antigen, using the amplified enzyme-linked immunosorbent assay (a-elisa), has been demonstrated in a model system in which bovine immunoglobulins (Ig) IgG1, IgG2, IgA, and IgM antibodies to human serum albumin (hsa) were measured. Comparative measurements are facilitated because the same enzyme-antibody complex is used for measuring all 4 isotypes. Serum dilutions from 1:100 to 1:50,000,000 were titrated and, when graphed logarithmically, yielded dose-response plots that contained a linear segment for all but IgA anti-hsa. Data obtained with whole serum and fractions enriched in IgA- and IgM-anti-hsa indicated that dimeric IgA antibodies may compete poorly with those of the IgM and IgG classes and that IgM antibodies are more avid than those of the IgG1 and IgG2 subclasses. Plateauing of complete a-elisa titrations at optical density (OD)400 nm values lower than those observed for their standard-curve counterparts was interpreted to result from saturation of the antigen.

Quantitation was accomplished through the use of standard curves prepared by adsorbing purified, radio-labeled Ig of the 4 isotypes directly to polystyrene. These plots were also valuable in evaluating antiglobulin specificity and potency and for ascertaining linearity in the absence of the primary antibody to be measured, as well as standard curves for determining antibody content in absolute terms. The absolute amounts of IgG1 and IgG2 antibodies to hsa were similar to those determined by quantitative precipitation and constituted about 25% of the total IgG1 and IgG2 in a hyperimmune bovine serum. Only 5% of the serum IgM was specific antibody to hsa. The specificity of various anti-bovine globulin reagents was further shown by demonstrating the characteristic distribution of IgG1, IgG2, IgM, and IgA anti-hsa in serum fractionated on Sephadex QAE-50 and in sucrose density-gradients.

Finally, data on the influence of enzyme-complex concentrations, complex-step incubation times, and the reaction kinetics of soluble antibody-enzyme complexes on a-elisa results are presented.
Morphogenesis of Vesiculation in Foot-and-Mouth Disease
Authors: Yilma Tilahun
Published: February 2025

The morphogenesis of vesiculation in cattle inoculated (aerosol exposure) with foot-and-mouth disease virus was investigated by examining alternate, frozen sections of selected tissues stained by fluorescent antibody technique and with hematoxylin and eosin. Viremia preceded the development of lesions, and virus appeared to be transported to the epithelium via papillae. Lesions were initiated usually by the infection of single cells in the stratum spinosum adjacent to the papillae. Three types of lesions were observed. A vesicle developed mainly from the lysis of swollen, spherical cells and the release of intracellular fluid. The 2nd type of lesion was formed mainly by the accumulation of intercellular edema. The 3rd type was characterized by the absence of a vesicle due to seepage and loss of edema fluid and desiccation of the lesion.
Effect of Intraluminal Oxygen in Intestinal Strangulation Obstruction in Ponies
Authors: Moore J. N. , White N. A. , Trim C. Μ. , Garner H. E.
Published: February 2025

This study examined the effect of intraluminal oxygen administration on mucosal morphology following intestinal strangulation obstruction (iso) in anesthetized ponies. The iso was produced by ligation of the intestinal vasculature in 5 ponies for 50 minutes and 2 ponies for 90 minutes. Two ponies served as controls. Light and scanning electron microscopic examination of intestinal biopsy specimens revealed progressive mucosal degeneration following iso in nontreated intestines, whereas high magnification scanning electron microscopic examination documented subtle evidence of microvilli disruption 120 minutes following iso in oxygen-treated intestines.
Influence of Head Height on Arterial Blood Pressure in Standing Horses
Authors: Parry B. W. , Gay C. C. , McCarthy Μ. A.
Published: February 2025

Eighteen horses were used to investigate the influence of head position on arterial blood pressure, measured indirectly at the coccygeal artery. Head height significantly altered systolic pressure, diastolic pressure, pulse pressure, and mean arterial pressure, such that head-lowering decreased and head-raising increased all variables.
Thiabendazole-Resistant Strains of Haemonchus and Ostertagia in California Lambs
Authors: Miller James E. , Baker Norman F.
Published: February 2025

Ten parasite-free experimental lambs were inoculated intraruminally with a mixed-larvae inoculum which contained approximately 5,000 Haemonchus contortus infective larvae. Five lambs were treated with thiabendazole (66 mg/kg of body weight) and 5 were untreated controls. All lambs were killed 35 days after inoculations were done, and parasites present were recovered. Reduction in numbers of recovered Haemonchus contortus (25.7%) and Ostertagia spp (26.8%) were not significant (P > 0.05).
Caprine Mycoplasmosis: Mycoplasma putrefaciens, a New Cause of Mastitis in Goats
Authors: Adler H. E. , DaMassa A. J. , Brooks D. L.
Published: February 2025

Lactating goats given an intramammary inoculation of 50 Mycoplasma putrefaciens in 1/2 of the udder had a high percentage of leukocytes in the milk within 8 days, without involvement of the other half. Larger doses of mycoplasma caused earlier inflammatory changes, but there were no differences in the final disease. In all instances, the viability count of the mycoplasma reached at least 108 organisms/ml before a high percentage of neutrophils were present in milk smears. The California mastitis test was 2+ to 3+ when 1010 Μ putrefaciens/ml were cultured from the secretions. The main features of Μ putrefaciens infection in the udder are the lack of clinical signs and rapid growth of the organisms, followed by inflammatory cells in the milk and complete halt to lactation.
Evidence of Cytocidal Effects of Pasteurella haemolytica on Bovine Peripheral Blood Mononuclear Leukocytes
Authors: Kaehler Karen L. , Markam R. J. F. , Muscoplat Charles C. , Johnson Donald W.
Published: February 2025

Pasteurella haemolytica had a pronounced cytocidal effect on bovine mononuclear leukocytes. Mononuclear leukocytes separated from venous blood on Ficoll-diatrizoate and incubated with either P haemolytica or Escherichia coli showed a significantly greater percentage cell death than did cells incubated with Staphylococcus epidermidis or controls. Neither heat-killed nor x-irradiated P haemolytica caused a significant percentage cell death. The cytotoxic potential of P haemolytica was dose related in that cell death among mononuclear leukocytes increased as the ratio of bacteria-to-cells increased. Enriched monocyte cultures showed a higher and less variable rate of cell death than either enriched lymphocyte or mixed leukocyte cultures.
Persistence on Pasture of the Infective Larvae of Nematodes Parasitizing Maine Dairy Cattle
Authors: Gibbs H. C.
Published: February 2025

Yearling calves infected with Ostertagia ostertagi, Cooperici oncophora, and Nematodirus helvetianus were allowed to graze on a 0.8 ha pasture plot contaminated during June and August 1977. In June 1978, the plot was subdivided into 10 subplots of equal size. Grazing in 5 of these plots was allowed, each for 1 month, during June, July, August, September, and October by groups of 2 parasite-free 16-week-old calves. The procedure was repeated in 1979 with the remaining 5 subplots. Each group of calves was allowed to graze for 2 weeks, then put into stalls for 2 weeks and killed and examined for worms.

There was good survival of the 3 worm genera over the winter period of 1977–78. In June, calves averaged 250 Ostertagia, 5,345 Cooperia, and 6,955 Nematodirus. Ostertagia and Cooperia were recovered from calves grazing in September and October. The 3rd genus, Nematodirus, also became less plentiful over the summer period, but persisted in calves grazing during September and October. This genus survived a 2nd winter on pasture and worms were recovered until July, 1979.
Thoracic Radiography of the Normal Rhesus Macaque (Macaca mulatta)
Authors: Silverman S. , Morgan J. P.
Published: February 2025

Thoracic radiographs of rhesus macaques should be performed with short exposure times (1/60 s or faster) and the patient in the erect position. The patient's neck should be extended dorsally, and the arms extended above and behind the head. The tracheobronchial and lobar pulmonary anatomic features of the rhesus macaque are similar to those of the dog. The pulmonary parenchymal pattern also is similar: however, the interstitial markings are somewhat more prominent in the macaque. This may be due to lung mite infestation. The macaque does not appear from a radiologic standpoint to be superior as an animal model to dogs or cats unless there is something specific about the response or susceptibility to a disease being studied.
Guaifenesin: Cardiopulmonary Effects and Plasma Concentrations in Horses
Authors: Hubbell J. A. E. , Muir W. W. , Sams R. A.
Published: February 2025

We determined the cardiopulmonary changes in horses given guaifenesin alone and in the same horses given xylazine (iv) immediately before administration of guaifenesin. In addition, plasma guaifenesin concentrations were determined in horses and 2 pregnant mares and compared with previously published values in ponies. The dose of guaifenesin necessary to produce lateral recumbency in adult horses was 134 ± 34 mg/kg (mean ± sd). The administration of guaifenesin caused insignificant (P < 0.05) changes in heart rate, respiratory rate, right atrial pressure, pulmonary arterial pressure, and cardiac output. Systolic, diastolic, and mean arterial blood pressures were significantly (P < 0.05), decreased. Arterial partial pressure of oxygen (PaO2) was transiently, but significantly (P < 0.05), reduced.

The administration of xylazine (iv) to the horses before they were given guaifenesin reduced the dose of guaifenesin necessary to produce lateral recumbency to 88 ± 10 mg/kg. In these horses, there were significant transient decreases in heart rate, respiratory rate, cardiac output, and PaO2. Central venous pressure remained significantly (P < 0.05) increased, whereas systolic, diastolic, and mean arterial blood pressures were significantly (P < 0.05) decreased at all times. In horses given guaifenesin alone, plasma concentrations at the time of lateral recumbency were 313 ± 108 μg/ml, and in those given xylazine-guaifenesin, the concentrations of the drug were 277 ± 83 μg/ml. Neonatal concentrations of guaifenesin were approximately 30% of that of the mare immediately after delivery, indicating that significant amounts of guaifenesin cross the placental barrier in the mare.
Progesterone Monitoring of Anestrous Dairy Cows and Subsequent Treatment with a Prostaglandin F2α Analog or Gonadotropin-Releasing Hormone
Authors: Humblot P. , Thibier M.
Published: February 2025

A field study was conducted in 3 large dairy herds (50 to 300 cows) which were the objects of a reproductive health-status program, including the use of a progesterone measurement in plasma or milk. The anestrous syndrome was specifically studied and was defined as no estrus occurrence by postpartum day 60 (postpartum anestrus) or by 21 to 24 days after insemination, if a negative early pregnancy test based on milk progesterone concentrations was obtained (postinsemination anestrus). Two treatments were tested; gonadotropin-releasing hormone or a prostaglandin F2α analog was used according to results of progesterone monitoring. In the largest herd, reproductive performances were recorded on 2 successive years before and after the beginning of such a reproductive health program. The overall decrease in the nonpregnant days was 17 days. This was due to (i) early and appropriate usage of prostaglandin F2α analog in cycled postpartum anestrous cows, as well as in cows not seen in estrus and not pregnant after insemination, and (ii) to shortening of the nonpregnant period in noncycling anestrous cows treated with gonadotropin-releasing hormone and monitored simultaneously in terms of progesterone concentrations.
Minimal Interferon Induction in Dogs, Using a Modified Polyriboinosinic-Polyribocytidylic Acid Complex
Authors: Smith Jean S. , Yager Pamela A. , Baer George M.
Published: February 2025

Adult Beagles failed to respond to high concentrations of interferon (if) when they were injected with a nuclease-resistant complex of poly I:C with poly-l-lysine and carboxymethylcellulose (piclc), by the iv or intrathecal route. An iv dose of 1 mg of piclc/kg of body weight was lethal to 1 of 3 adult dogs, but induced if in only 2 dogs. Smaller doses were less toxic, but also were less effective. The injection of a high dose of a known if inducer (3 × 108 egg ld50 of Newcastle disease virus) also failed to induce if in Beagles. Interferon could not be induced in vitro when primary cultures of neonatal dog lung or kidney were treated with piclc. When these primary cell cultures were compared with the cell line Madin-Darby canine kidney in an if assay, no difference in sensitivity to if-induced protection from infection with vesicular stomatitis virus could be shown. This indicated that the sensitivity of the Madin-Darby cell line was not the only factor in determining the lack of if response in dogs and indicates that the dogs are poor responders to if induction.
Atypical Hog Cholera Infection: Viral Isolation and Clinical Study of in Utero Transmission
Authors: Plateau E. , Vannier Ph. , Tillon J. P.
Published: February 2025

Sows in different stages of pregnancy were inoculated with a low-virulence hog cholera strain. Clinical signs of disease were not observed in the sows during pregnancy, but most of their pigs were splaylegged and had nervous disorders; perinatal mortality was high.

A few pigs from sows that were inoculated during the 1st trimester of pregnancy survived and remained inapparent carriers of virus, without developing antibodies. Seemingly, these pigs were immunotolerant. Virus was transmitted from immunotolerant pigs to susceptible pigs by contact 5 weeks after farrowing, but not 3 months after farrowing, despite the persistence of the virus at a high concentration in the blood and in the organs of the immunotolerant pigs.
Pathologic Alterations in Hypertrophic and Congestive Cardiomyopathy of Cats
Authors: Van Vleet John F. , Ferrans Victor J. , Weirich Walter E.
Published: February 2025

Pathologic alterations were studied in 15 cats with cardiomyopathy. Ten of these had hypertrophic cardiomyopathy, characterized by cardiomegaly, diffuse myocardial hypertrophy, small left ventricular cavities, and dilated left atria; the ventricular septum and left ventricular free walls were thick, but asymmetric septal hypertrophy was not present. Aortic thromboembolism, renal infarction, and pulmonary congestion and edema were frequent.

Histopathologic and ultrastructural study revealed hypertrophy and disarray of cardiac muscle cells (most severe in left ventricle and ventricular septum) interstitial fibrosis and fibromuscular hyperplasia of small intramurai coronary arteries. The hypertrophied fibers had large nuclei, prominent Golgi complexes, and numerous polysomes; some fibers had crisscrossing myofibrils. Degenerative alterations in hypertrophied myocytes were: perinuclear distension of elements of sarcoplasmic reticulum, focal myofibrillar lysis, numerous thick clumps of Z-band material, and abundant lipofuscin granules. The interstitium showed accumulations of collagen fibrils, increased numbers of fibroblasts, and scattered remnants of external lamina. One cat had dilated chambers, but also had typical histologic and ultrastructural alterations of hypertrophic cardiomyopathy and was considered to have a late stage of this disorder. Four cate had congestive cardiomyopathy, with cardiomegaly and dilatation of all chambers. Hydrothorax and pulmonary congestion and edema were generally present. Cardiac histopathologic and ultrastructural alterations consisted only of mild interstitital edema and fibrosis.

Detailed comparisons reveal many similarities in the spectrum of morphologic features of hypertrophic cardiomyopathy in human beings and cats; there are not marked differences in the morphologic features of congestive cardiomyopathy in human beings and cats. Thus, cardiomyopathies in the cat constitute useful models for the study of these diseases in human beings.
Characterization of Equine Alkaline Phosphatase Isoenzymes Based on Their Electrophoretic Mobility by Polyacrylamide Gel Disc Electrophoresis
Authors: Dumas M. B. , Spano J. S.
Published: February 2025

Alkaline phosphatase isoenzymes of equine tissues, peritoneal fluid, and serum were characterized by their electrophoretic mobilities, using polyacrylamide gel disc electrophoresis. The alkaline phosphatase isoenzymes in liver, kidney, spleen, small intestine, placenta, bone, small colon, and large colon tissue samples were extracted and separated by electrophoresis. The resulting isoenzyme mobilities and spectrophotometric scans were evaluated for their tissue specificity and for their possible use in determining the tissue contribution of alkaline phosphatase to serum and peritoneal fluid. The sensitivity of the tissue alkaline phosphatase to heating at 56 C was also determined. The isoenzymes of all the tissue extracts, except small intestine and large colon, were distinguishable from one another by their specific electrophoretic mobilities and patterns and by their sensitivity to heating at 56 C. The mobilities and patterns of small intestine and large colon isoenzyme extracts were not different enough to allow making a differentiation, but the heat resistance of small intestine did distinguish it from large colon. The tissue sources of alkaline phosphatase in the serum of healthy adult horses, pregnant mares, and normal foals and in the peritoneal fluid of healthy horses were determined by characterization of the mobilities of their isoenzymes.
Manipulating Energy Metabolism in Sheep Exposed to Cold
Authors: Horton G. M. J.
Published: February 2025

The effects of dietary fat level (0 and 7% tallow) and monensin (0 and 33 mg/kg of diet) were investigated in lambs at ambient temperatures of −11.9 and 12.9 C. Twenty-four nonfistulated and 16 fistulated lambs with an average weight of 73 kg and fleece length of 8 cm were randomly assigned to each fat and monensin level (6 nonfistulated and 4 fistulated lambs per treatment) in a 2 × 2 factorial arrangement of diets. There were no main treatment effects on organic matter or crude protein digestibility, though ether extract digestibility was higher on the high-fat diets (P < 0.001) and at 12.9 C (P < 0.05). Fat decreased (P < 0.05) molar proportions of ruminal acetate and increased propionate. Monensin increased (P < 0.001) proprionate and decreased (P < 0.05) butyrate. Propionate was 26% higher at −11.9 C. Respiration rate tended to be higher on the high-fat diets and was doubled (P < 0.001) at the warm temperature (12.9 C). There were no main treatment effects on rectal temperature. Heart rate was increased (P < 0.05) by 12% on the high-fat diets. Cold temperature exposure significantly increased free fatty acids, thyroxine, protein-bound iodine and phosphorus, and decreased plasma urea nitrogen in jugular blood. Free fatty acid and triglyceride concentrations were higher (P < 0.05) on the high-fat diets. There were no main treatment effects on either glucose or calcium levels. These results show that dietary fat level and monensin did not consistently influence the sensitivity of full-fleeced lambs to the effects of cold-temperature exposure.
Recrudescence of Anaplasma marginale Induced by Immunosuppression with Cyclophosphamide
Authors: Corrier D. E. , Wagner G. G , Adams L. G.
Published: February 2025

Eight doses of cyclophosphamide (5 mg/kg), at 2-day intervals between doses, were administered iv to Anaplasma-carrier splenectomized calves. Significant decreases in serum immunoglobulins, diminished complement-fixing antibody response, and transitory leukopenia were associated with the treatment. Recrudescence of clinical Anaplasma infection occurred after the 5th dose of cyclophosphate was given and was characterized by rapid increase in parasitemia, marked decrease in pcv, and mortality. The results of the present study indicated that humoral mediated immunity may contribute to the maintenance of a state of equilibrium in the host-parasite relationship and that suppression of humoral immune responses may alter the course and outcome of infection in Anaplasma carriers.
Local and Systemic Reactions in Cattle to Hypoderma lineatum Larval Toxin: Protection by Phenylbutazone
Authors: Eyre Peter , Boulard Chantal , Deline Terrence
Published: February 2025

Soluble toxin of Hypoderma lineatum injected iv induced a severe cardiorespiratory shock syndrome in calves. Intradermal injection of the toxin caused well-defined, edematous wheals comparable with those produced by histamine. Treatment of calves with famphur (organophosphate insecticide; poured on the skin of the calves 24 hours before injection of toxin) did not increase the severity of the effects of the toxin. Treatment of calves with phenylbutazone (20 mg/kg) 20 minutes before injection of toxin protected the calves against the systemic shock syndrome and the local inflammatory reaction. Apparently, the neurotoxic mechanism of the organophosphate insecticide is independent of the action of the Hypoderma toxin per se. Phenylbutazone can control the effects of the Hypoderma toxin.
A Swine Dysentery Model for Evaluation of Drug Prophylaxis: Development of a Model Involving Oral Infection Plus Pen Contamination
Authors: Raynaud J. P. , Brunault G. , Patterson E. B.
Published: February 2025

To overcome some of the inadequacies of the classic artificial swine dysentery (sd) model that is frequently used to judge the efficacy of drugs in preventing sd, a model has been developed that produces sd comparable with natural infections that are frequently encountered in commercial pig production facilities. The model is a combination of a single oral infection (oi) plus pen contamination (pc), conducted each night for 25 nights. Results with oi alone, pc alone, and oi + pc have been compared, and the new model (oi + pc) produced consistent, homogeneous, and severe sd with 100% morbidity and 92% mortality.
Evaluation of Lasalocid in Salt Against Ovine Coccidia
Authors: Foreyt William J. , Gates N. L. , Rich James E.
Published: February 2025

Lasalocid at a level of 0.75% in free-choice granulated salt was highly efficacious against naturally acquired coccidia infections in lambs maintained in semiconfinement. Treated lambs consumed 18 g of medicated salt/day, reflecting an average daily lasalocid dosage of 4.3 mg/kg of body weight. Treated lambs gained 5.7 kg more than did untreated lambs (P < 0.01) during the 84-day experiment. Clinical signs of coccidiosis were not observed in treated or untreated lambs.
Therapeutic Effects of Parenteral Administration of Lincomycin on Experimentally Transmitted Swine Dysentery
Authors: Hamdy A. H. , Kratzer D. D.
Published: February 2025

The therapeutic effects of 2 dose levels of lincomycin and a reference drug (tylosin) were compared in 80 growing pigs with experimentally transmitted swine dysentery (sd). The pigs were allotted equally to 4 groups. Treatment was initiated 5 days after pigs were exposed to sd. Lincomycin was administered im at doses of 11.0 or 4.4 mg/kg of body weight once daily for 3 to 7 days. Tylosin was injected im at a dose of 8.8 mg/kg once daily for 3 days (highest recommended dose). The control (nontreated) infected pigs were not given the drug. The study was terminated 22 days after exposure to sd. The effects were measured in terms of mortality, survival time, dysentery, spirochetal shedding, fecal consistency, physical activity, performance, and necropsy findings.

The 2 drugs reduced the clinical signs of sd. Pigs treated with either dose of lincomycin had a better treatment response than did pigs treated with tylosin, as evidenced by less mortality, longer survival time, and greater feed intake (P = 0.05). In addition, pigs treated with the larger dose of lincomycin, 11.0 mg/kg, had better treatment responses in 12 of the 14 measured criteria than did pigs treated with tylosin. Also, these pigs treated with the larger lincomycin dose had better treatment responses than did the pigs treated with the smaller dose of lincomycin, 4.4 mg/kg, as evidenced by dysentery, fecal consistency, physically active and intermediately active pig days, body weight gain, and feed intake.
Internal Vomiting in the Ruminant: Effect of Apomorphine on Ruminal pH in Sheep
Authors: Eiler H. , Lyke W. A. , Johnson R.
Published: February 2025

Five sheep, with a rumen fistula inserted, were each injected (iv) with apomorphine (18 mg) and ruminal pH was measured every 5 minutes during a 1-hour period. During the base-line period (30 minutes) that preceded apomorphine injection, pH was constant in individual sheep and the group mean (± sd) was 7.1 ± 0.35. After apomorphine was injected, group mean was 6.9, 6.0, 6.3, 6.3, 6.3, 6.4, 6.4, 6.5, 6.7, 6.9, 6.9, and 7.1 at 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 minutes, respectively. The pH reduction of ruminal content was recorded in 4 of the sheep. Maximal reduction occurred in the 10-minute period after apomorphine was injected. The pH returned to control value within 40 to 50 minutes after injection. Vomitus was not expelled through the mouth by any of the sheep. It was concluded that expulsion of acidic abomasal contents back into the preabomasal compartment (internal vomiting) was the cause of acidification of the rumen after apomorphine was injected.
Effect of Rush Pins on the Distal Femoral Growth Plate of Young Dogs
Authors: Stone E. A. , Betts C. W. , Rowland G. N.
Published: February 2025

Rush pins were placed in the distal portion of the left femur in 15 young (4 months old) mongrel dogs. Microscopic evaluation of the growth plate showed closure beginning 1 month after the pins were implanted and complete closure occurring a month earlier than in the control (right) femur. The left femurs had a mean decrease in length of 22 mm compared with the length of the control femurs at the time of growth plate closure. When the Rush pins were removed 1 month after implantation, the growth plate regained normal microscopic appearance and difference in femur lengths (left vs right) did not occur. Tibial length did not change relative to femur length. Recommendations are made about the use of Rush pins in young dogs.
Orientation and Configuration of Vectorcardiographic QRS Loops from Normal Cats
Authors: Coulter Dwight B. , Calvert Clay A.
Published: February 2025

The orientations (angles) of mean QRS vectors were manually calculated from scaler orthogonal leads (I, aVf, V10; X, Y, Z) and from X-Y oscilloscope recordings from cats injected with ketamine and acetylpromazine. Those angles calculated from individually recorded leads (I, aVf, and V10) were from cats in right lateral and sternal recumbency. Leads X, Y, and Z were recorded simultaneously from cats in sternal recumbency. The oscilloscope recordings were derived from the X, Y, and Z leads. Arithmetic and maximal measurements from ecg scaler leads and maximal and half area measurements from oscilloscopic recordings were used for calculations. Recordings were from 15 cats and from 1 cat 15 times. Based on visual inspection of scattergrams, the X, Y, and Z vectors were not different in orientation from I, aVf, and V10 vectors. Orientation of oscilloscopic vectors were more variable than orientations of vectors calculated from scaler leads. Body position of the cat during recording did not affect mean values of angles derived from leads I, aVf, and V10. Type of measurements did not affect mean values. Variation of orientation was greater among cats than for the intraindividual vector orientations. Configuration and direction of QRS loops from 27 normal cats were also recorded. The greatest variation in loop configuration was in the frontal plane.
Infection Studies in Kittens, Using Feline Infectious Peritonitis Virus Propagated in Cell Culture
Authors: Pedersen Niels C. , Boyle John F. , Floyd Kim
Published: February 2025

The propagation of feline infectious peritonitis virus (NW1-FIPV strain) in cell culture is described. Tissue culture-propagated virus was used to inoculate specific-pathogen-free kittens intraperitoneally, intratracheally, or orally. Intraperitoneal inoculation caused seroconversion and effusive peritonitis in 100% of the kittens. Intratracheal inoculation produced disease in 60% of the kittens, and oral inoculation in only 20%.

Seroconversions without production of disease occurred in 10% of the kittens inoculated by either the intratracheal or the oral route. The remainder of the kittens inoculated by the intratracheal (30%) and oral (70%) routes did not develop serum antibodies or disease.
Pathogenesis of Feline Infectious Peritonitis: Nature and Development of Viremia
Authors: Weiss Richard C. , Scott F. W.
Published: February 2025

Kittens that were seropositive or seronegative to feline infectious peritonitis virus (fipv) and were experimentally infected with fipv by aerosol exposure developed a persistent cell-associated viremia. When test kittens were inoculated with whole blood, intact or disrupted buffy coat (bc) cells, or cell-free supernatants of disrupted bc cells from these infected kittens, the test kittens developed feline infectious peritonitis (fip). When test kittens were inoculated with plasma or wbc-free erythrocyte suspensions from the infected kittens, they did not develop fip.

Viremia could not be detected in healthy fipv-seropositive kittens before aerosol challenge exposure. Viremia was first detected on postchallenge-exposure day (pcd) 2 in seropositive kittens and on pcd 6 in seronegative kittens. The onset of viremia correlated with the appearance of fever, pulmonary vascular lesions, and fipv antigen in lung macrophages of infected kittens. The fipv-infected wbc were detected by immunofluorescence microscopy in the lumen, intima and wall of pulmonary veins and in perivascular foci in lungs of viremic kittens. Marked pulmonary necrosis and severe clinical disease occurred by pcd 7 in seropositive kittens and on or after pcd 16 in seronegative kittens. Significant (P < 0.05) reductions in numbers of circulating platelets and lymphocytes developed earlier in seropositive kittens than in seronegative kittens. Survival times in seropositive kittens were significantly (P < 0.001) decreased compared with survival times in seronegative kittens.

Immunofluorescent or electron microscopic examination of blood smears and bc cells from viremic kittens failed in most instances to demonstrate intracellular virus or viral antigen. Specific antiviral immunofluorescence was, however, readily observed in bc cells from viremic kittens when the cells were maintained in vitro for ≥ 24 hours.

Seemingly, an immune-mediated mechanism is involved in the pathogenesis of fip. The fipv-seropositive kittens developed viremia, antiviral immunofluorescence, and lesions earlier and died more rapidly after virus challenge exposure than did fipv-seronegative kittens. In both groups, a fatal disease characterized by progressive vasculitis and necrosis developed during a period of persistent viremia and elevated or increasing serum antibody titers.