bluuebunny/crossref_metadata_2025 huggingface dataset:
Pasteurella haemolytica serotype 1 colonization of the nasal passages of virus-infected calves
Authors: Frank Glynn H. , Briggs Robert E. , Gillette Kenneth G.
Published: February 2025

Nasal passages of calves with a virus-induced respiratory tract disease became colonized by Pasteurella haemolytica serotype 1 after they were inoculated intranasally with P haemolytica. Inoculation with infectious bovine rhinotracheitis virus caused a more severe clinical illness and resulted in a greater degree of colonization with P haemolytica than developed after inoculation with parainfluenzal virus. Nasal passages of parainfluenza-3 virus-inoculated calves were colonized to a greater degree with P haemolytica than were those of healthy, non-stressed calves. Calves were susceptible to P haemolytica colonization during or shortly after virus-induced illness, even though they had been previously exposed to P haemolytica and had serum antibody and nasal secretion antibody to P haemolytica.
Unipolar thoracic electrocardiograms in which P waves of relative uniformity occur in male horses
Authors: Illera J. C. , Hamlin R. L. , Illera M.
Published: February 2025

Bipolar and unipolar limb leads and unipolar thoracic lead ecg were obtained from 100 male crossbred horses. P-wave morphologic features were classified according to positivity negativity and monopolarity dipolarity, and the percentage of horses that had P waves of a given morphologic class in each lead was calculated. P-Wave morphologic features of 4 precordial leads were most uniform, with > 80% of the horses having a single configuration.
Morphologie features of Sertoli cells in the intra-abdominal testes of cryptorchid dwarf goats
Authors: Ezeasor Daniel N. , Singh Amreek
Published: February 2025

Light and electron microscopy revealed an age-related progression of alterations of Sertoli cells in the intra-abdominal and scrotal testes of unilaterally cryptorchid West African dwarf goats between the ages of 1 and 30 months. Alterations in the scrotal testis were, however, matura-tional and included differentiation of Sertoli-to-Sertoli cell junctional specializations, profusion of smooth endoplasmic reticulum, convolution of nuclear profiles, development of vacuolar components of the nucleolus, and an overall change in cell shape in response to proliferation of germinal cells. Corresponding features were observed in Sertoli cells of the contralateral intra-abdominal testis, but the cytoplasmic features were transient because the cells degenerated progressively. Early changes included segregation of the smooth endoplasmic reticulum into compact masses composed of dense, narrow cisternae, dilatation of the rough endoplasmic reticulum cisternae into large, irregular profiles, atrophy of the Golgi complex, and accumulation of lipid droplets and lipofuscin granules. Many of these organelles and inclusions no longer were obvious in Sertoli cells of 12- to 15-month-old goats; rather, intracellular vacuoles and dilated intercellular spaces had become common. In the 24- to 30-month-old goats, Sertoli cells in the intra-abdominal testis contained mostly microfilaments and basally located mitochondria with circular cristae in dense matrices. The Sertoli-to-Sertoli cell junctional specializations were structurally intact. These results indicated that, in spite of the unfavorable intra-abdominal environment, Sertoli cells of the intra-abdominal testis, before their degeneration, had developed features similar to those of the scrotal testis.
Influence of interferon in natural resistance of mice to Sendai virus pneumonia
Authors: Breider Michael A. , Adams L. Garry , Womack James E.
Published: February 2025

The influence of interferon (ifn) on the natural resistance to Sendai virus was investigated in resistant (C57BL/ 6NCr) and susceptible (DBA/2NCr) mouse strains. After inoculation with strain 52 Sendai virus, the pulmonary titers of Sendai virus were similar in both mice strains, indicating that the quantity of virus in the lungs may not be a major factor in determination of resistance. The pulmonary ifn titers were higher in DBA/2 mice, indicating that increased susceptibility of DBA/2 mice is not a result of inadequate production of ifn. Treatment of both strains with exogenous ifn before and during viral infection induced an increased survival time in C57BL/6 mice, but eventual mortality was the same in both mouse strains. Administration of anti-ifn antibodies to both mouse strains during Sendai infection decreased mortality equally in both strains, compared with mortality in control mice. Seemingly, the difference in resistance to Sendai virus in DBA/2 and C57BL/6 mice was probably not a result of the beneficial effects of ifn. On the contrary, administration of anti-ifn antibodies decreased the susceptibility of both mouse strains.
Efficacy of amoxicillin trihydrate for the treatment of experimentally induced foot rot in cattle
Authors: Braun R. Kenneth , Bates Douglas B. , Shearer Jan K , Tran Thang Q. , Keiey Mohamed El
Published: February 2025

Twenty holstein heifers were intradermally inoculated in the interdigital skin with a suspension containing Fusobacterium necrophorum and Bacteroides melaninogenicus to induce acute foot rot. Lesions, lameness, and swelling were evaluated during the study, using a subjective scoring system. Rectal temperature, species and number of bacteria isolated, and change in body weight were monitored throughout the study.

Ten heifers (treated) were given amoxicillin trihydrate (10 mg/kg of body weight, im) for 5 days, beginning at the onset of lameness. The remaining 10 heifers (controls) were given physiologic saline solution im. Treated heifers had less severe lesions and greater weight gain than did control heifers. Rectal temperatures of treated heifers did not differ significantly from those of control heifers. It was concluded that administration of amoxicillin trihydrate early in the course of acute foot rot may reduce the severity of lesions associated with foot rot in cattle.
Reproductive evaluation of male Beagles and the safety of ivermectin
Authors: Daurio Carolyn P. , Gilman Martin R. , Pulliam James D. , Seward R. Lee
Published: February 2025

Ivermectin had no adverse effects on spermatogenesis, fertility, or reproductive performance of Beagle dogs when administered orally at 600 μg/kg (0.6 mg/kg) of body weight monthly for 8 treatments. Semen was collected every 3 days from 28 days before treatment began until 83 days thereafter from 6 ivermectin-treated Beagles and 6 similar water-treated controls (38 collections/dog). All dogs were then bred to 2 nontreated bitches each; litter size, birth weights, and pup abnormalities and mortalities were evaluated. After all pups were whelped, each dog was euthanatized and necropsied, and the testis and epididymis were examined microscopically.
Healing of transverse humeral fractures in pigeons treated with ethylene oxide-sterilized, dry-stored, onlay cortical xenografts and allografts
Authors: MacCoy Douglas M. , Haschek Wanda M.
Published: February 2025

Transverse humeral fractures were created in adult male pigeons (Columbia livia). They were bridged with an allograft or a xenograft, or they were allowed to heal without treatment. Tissues were examined for wound healing, bony union, infection, and sequestration of the graft at 28, 43, 85, 106, and 168 days after surgery. Neither allografts nor xenografts contributed to nor interfered with bone healing. In nontreated pigeons (controls), bony union with marked callus formation developed between misaligned fragment ends. When onlay grafts were used, bone fragments remained aligned, with minor callus formation. There was a significant (P = 0.0001) increase in the number of wounds opening after surgery and infections of the surgical site (xenograft, P = 0.0026; allograft, P = 0.0021) associated with graft use. A significant (P = 0.0001) frequency of graft sequestration was observed, regardless of graft type. A significant (P = 0.0001) frequency of foreign body reaction also was observed. Under these circumstances, the application of a graft should be considered as an alignment device, rather than a stimulus to healing.
Effect of atropine on cystometry and urethral pressure profilometry in the dog
Authors: Barsanti J. A. , Finco D. R. , Brown J.
Published: February 2025

Effects of atropine on cystometry and urethral pressure profilometry were examined in 12 healthy young adult dogs by comparing recordings obtained after xylazine alone with those obtained after administration of xylazine and atropine. Significant differences (P > 0.05) were not found, indicating that atropine, when administered sc with xylazine, did not markedly affect cystometrographic results and urethral pressure profiles.
Hereditary parakeratosis in Shorthorn beef calves
Authors: Vogt D. W. , Carlton Carol G. , Miller R. B.
Published: February 2025

Parakeratosis was diagnosed in 9 Shorthorn beef calves over a 4-year period. When pedigrees of these calves were analyzed, familial associations were strong. Thirty-six coefficients of relationship among all possible combinations of the 9 affected calves ranged from 0.5 to 39.8% and averaged 15.6%. All affected calves were descendants of bull A. Of 9 affected calves, 6 had bull A in their paternal and maternal pedigrees. The 3 remaining affected calves had bull A in their sire's pedigree and were born to 2 full-sib dams. Seemingly, parakeratosis in this Shorthorn herd was hereditary with the mode of inheritance being that of a simple autosomal recessive.
Total parenteral nutrition in four healthy adult horses
Authors: Hansen Thomas O. , White Nathaniel A. , Kemp Douglas T.
Published: February 2025

Total parenteral nutrition was accomplished in 4 healthy adult horses. During the 10-day study, the horses were not permitted to ingest food or water. Body weight was maintained at 94% of initial values without clinical evidence of dehydration. Serum urea nitrogen and triacyl-glycerol concentrations decreased during the study, without other significant hematologic or biochemical changes. Horses adapted without problems to the routine of iv feeding and confinement. All horses were healthy at the conclusion of the study. It was concluded that intravenous feeding with a lipid-glucose-amino acid-electrolyte solution was an acceptable method of maintaining nutrition in the healthy adult horse.
Plasma heparin values and hemostasis in equids after subcutaneous administration of low-dose calcium heparin
Authors: Gerhards Hartmut , Eberhardt Christiane
Published: February 2025

Different doses of heparin were given to equids sc to establish 0.05 to 0.20 U of heparin/ml of plasma. Plasma heparin values and antithrombin III activities were assayed, using chromogenic substrate methods. Activated partial thromboplastin and thrombin times were determined, using conventional coagulation assays. Tests were run every hour (or every 2 hours for antithrombin III) for 12 hours from 5 groups of 5 equids each after single injection of 40, 60, 80,100, or 125 U of calcium heparin/kg of body weight and from 11 equids after injection of 150 U of calcium heparin/kg.

The smaller dose (40 U/kg) did not or only insufficiently increase plasma heparin values. After 150 U of heparin/kg, plasma heparin concentrations were increased for 11 hours and were significantly (P = 0.05) increased between postadministration hours 2 and 7. The desired range beyond 0.05 U of heparin/ml was achieved between postadministration hours 2 and 6. Antithrombin III, activated partial thromboplastin time, and thrombin time were not significantly affected by any heparin dose.

In cumulative studies, 2 equids were given 150 U of heparin/kg 7 times at 12-hour intervals. After the 3rd injection, a mean plasma concentration of 0.20 U of heparin/ml was achieved; after the 7th injection, the mean concentration was 0.22 U of heparin/ml. Four equids were given 150 U of heparin/kg initially, followed by 125 U of heparin/kg 6 times at 12-hour intervals. After the 3rd injection, a maximal plasma heparin concentration of 0.12 U of heparin/ml was achieved; after the 7th injection, the mean concentration was 0.18 U of heparin/ml. Repeated sc heparin injections caused moderate swelling at the injection sites. After similar heparin doses, great interindividual and intraindividual variations in resulting plasma heparin concentrations were observed. Between 2100 and 0900 hours, plasma heparin values were higher than those between 0900 and 2100 hours.

Seemingly, sc administration of 150 U of heparin/kg, followed by 125 U of heparin/kg at 12-hour intervals, resulted in plasma heparin values between 0.05 and 0.20 U of heparin/ml. This heparin regimen may be useful for efficacious low-dose heparin prophylaxis in equids.
Pharmacokinetics of gentamicin after intravenous, intramuscular, and subcutaneous administration in cats
Authors: Jernigan Antoinette D. , Wilson Robert C. , Hatch Roger C. , Kemp Douglas T.
Published: February 2025

Six adult mixed breed cats were given 5 mg of gentamicin sulfate/kg of body weight by rapid iv, im, or sc injection. The serum concentration vs time data were analyzed, using a noncompartmental model based on statistical moment theory. The mean ± sd for the effective half-life after iv administration was 1.25 ± 0.30 hours. Mean residence time was 1.80 ± 0.43 hours. The apparent volume of distribution at steady state was 0.14 ± 0.02 L/kg. Total body clearance was 1.38 ± 0.35 ml/min/kg. Bioavailability was 67.8% after im and 76.2% after sc administration. A recommended dosage of 3 mg of gentamicin/kg every 8 hours was calculated; this dosage would induce an average steady state serum gentamicin concentration of 4 μg/ml. The sc route of administration was preferred because of rapid absorption, good bioavailability, and ease of administration.
Eructation of gas through the gastroesophageal sphincter before and after gastric fundectomy in dogs
Authors: Strombeck Donald R. , Turner W. Drew , Harrold Doris
Published: February 2025

The gas eructation function of the gastroesophageal sphincter (ges) was investigated in 6 conscious, fed dogs before and after gastric fundectomy. Using a perfused 4-lumen catheter with a Dent sleeve, gastric and ges pressures were measured. To induce eructation, nitrogen gas was insufflated (440 ml/min) into the stomach through one channel of the catheter. After base-line studies were completed on each dog, fundectomy, to remove 30% of the stomach, was performed. Mean (± sem) ges pressure was 45.3 ± 3.3 mm of Hg before fundectomy and 41.4 ± 1.9 mm of Hg after fundectomy (P > 0.05). Before fundectomy, treatment with metoclopramide or cisapride increased ges pressure to 62.2 ± 4.1 mm of Hg (P < 0.001) and 61.1 ± 5.0 mm of Hg(P < 0.05), respectively. Gastric contraction rates were the same, 4.92 ± 0.24/min and 4.80 ± 0.16/min before and after fundectomy, respectively.

During insufflation, gastric pressures before eructation increased to 12.2 ± 1.3 mm of Hg before fundectomy and to 13.6 ± 0.9 mm of Hg after fundectomy (P > 0.05). Eructation occurred at intervals of 1.44 ± 0.20 minutes before fundectomy and 1.56 ± 0.13 minutes after fundectomy (P > 0.05). Before fundectomy, administration of metoclopramide or cisapride resulted in eructation intervals of 1.72 ± 0.21 minutes and 1.39 ± 0.02 minutes, respectively; these intervals were not significantly different from those measured in dogs not given drugs. After fundectomy, the ges pressure in 5 dogs decreased and remained low during insufflation. After a series of normal eructation intervals, multiple eructations were observed in 4 of these dogs. Fundectomy did not impair ability to eructate gas from the stomach.
Efficacy of ivermectin against Cooperia curticei infection in sheep
Authors: Bogan James A. , McKellar Quintin A. , Mitchell E. Sian , Scott Elspeth W.
Published: February 2025

Lambs were inoculated with a single dose of Cooperia curticei. Subcutaneous administration of ivermectin at a dosage of 200 μg/kg of body weight resulted in 61.1% and 90.4% anthelmintic efficacy, when measured at 7 and 14 days after treatment, respectively. In the treatment groups, parasites that remained were located more distally in the small intestine than those in the lambs in the control groups.
Serologic studies of Actinobacillus (Haemophilus) pleuropneumoniae strains of serotype-3 and their antigenic relationships with other A pleuropneumoniae serotypes in swine
Authors: Mittal K. R. , Higgins R. , Lariviére S.
Published: February 2025

Serotype-3 strains of Actinobacillus (Haemophilus) pleuropneumoniae possess epitopes shared with almost all other Actinobacillus serotypes. Common epitopes detected in particulate antigens were heat-labile and heat-stable and were of minor nature. Additional cross-reactive epitopes were detected in soluble and particulate antigens prepared from strains of serotypes 3, 6, and 8. Crossreactions occurring between serotype-3 antigens and those of other serotypes were of 2 types: one associated mainly with 2-mercaptoethanol (2-me)-sensitive IgM antibodies and the other associated mainly with 2-me-resistant IgG antibodies. The cross-reactivity between serotypes 3, 6, and 8 was associated mainly with IgG antibodies, as shown by the results of 2-me tube agglutination, 2-me-indirect hemagglutination, and coagglutination tests. None of the tests was entirely satisfactory for serotyping serotype-3 isolates, mainly as a result of overlapping of type-specific antigenic determinants of serotypes 3, 6, and 8 in different combinations in the same strain. A combination of tests, using particulate and soluble antigens, may be necessary for typing of serotype-3 isolates.
Humoral immune response of the bovine fetus to in utero vaccination with attenuated bovine coronavirus
Authors: Mullaney T. P. , Newman L. E. , Whitehair C. K.
Published: February 2025

A fetal response to in utero vaccination with attenuated bovine coronavirus (9 to 49 days before parturition) was determined in 8 calves, 5 vaccinated and 3 controls. Calves were derived by hysterotomy before parturition and were maintained in a closed gnotobiotic environment.

The IgA, IgM, and IgG values and coronavirus-neutralizing antibody titers were higher in the sera and intestinal loop fluid from vaccinated calves than in those from control calves. Sections of ileum and ileal lymph nodes from 1-day-old vaccinated calves, when stained with monospecific anti-bovine IgG, IgM, and IgA had numerous positively stained plasma cells. Positive fluorescence was not detected in comparable tissues from controls.

When the 8 calves were given virulent coronavirus orally at 6 days of age, vaccinated calves did not become ill, whereas control calves had diarrhea in 19 to 22 hours. All calves were killed at 10 days of age. Control calves had lesions characteristic of coronavirus infection, and intestinal epithelial cells were positive by fluorescent antibody tests. In vaccinated calves, lesions of coronavirus infection were absent, and results of fluorescent antibody tests were negative. Although in utero vaccination with a coronavirus vaccine stimulated immunity in the newborn calf, the frequency of abortions (2 of 14 cows inoculated intra-amniotically) and premature births (4 of 14) precluded practical application.
Opsonin-dependent stimulation of bovine neutrophil oxidative metabolism by Brucella abortus
Authors: Canning Peter C. , Deyoe Billy L. , Roth James A.
Published: February 2025

Nonopsonized Brucella abortus and bacteria treated with fresh antiserum, heat-inactivated antiserum, or normal bovine serum were evaluated for their ability to stimulate production of superoxide anion and myeloperoxidase-mediated iodination by neutrophils from cattle. Brucella abortus opsonized with fresh antiserum or heat-inactivated antiserum stimulated production of approximately 3 nmol of O2-/106 neutrophils/30 min. Similarly treated bacteria also stimulated the binding of approximately 4.3 nmol of NaI/107 neutrophils/h to protein. Significant (P < 0.05) production of O2- and iodination activity by neutrophils were not stimulated by nonopsonized bacteria or organisms treated with normal bovine serum. Seemingly, B abortus stimulated oxidative metabolism in bovine neutrophils; however, the stimulation was dependent on the presence of bacterial associated opsonins.
Dysfunction of sense of smell caused by canine parainfluenza virus infection in dogs
Authors: Myers Lawrence J. , Nusbaum Kenneth E. , Swango Larry J. , Hanrahan Lynn N. , Sartin Eva
Published: February 2025

Olfactory function of 5 dogs that were naturally infected with canine parainfluenza virus and of 4 dogs that were inoculated with the C958 strain of canine parainfluenza virus was evaluated. Except for one dog that was inoculated, the threshold for detection of benzaldehyde and/or eugenol was found to be excessively high during the course of the disease, as determined by electroencephalographic and behavioral olfactometry. In experimentally infected dogs, an increase in threshold developed in the absence of other clinical signs of disease. Changes were not observed in electro-olfactograms recorded throughout the study. Olfactory thresholds returned to normal after the disappearance of clinical signs of disease in the naturally infected dogs. Necropsies and histologic examinations performed during the course of the disease did not reveal abnormalities of the olfactory mucosa.
Effects of phenobarbital on thiopental pharmacokinetics in Greyhounds
Authors: Sams Richard A. , Muir William W.
Published: February 2025

The effects of phenobarbital on the pharmacokinetics of thiopental (15 mg/kg iv) were investigated in 12 trained racing Greyhounds. Phenobarbital (16 mg/kg of body weight, po, q 24 h), administered for 14 days, reduced the area under the curve of plasma concentration of thiopental vs time from 10,688 μg·min/ml to 3,224 μg·min/ml. Furthermore, the time to recovery from anesthesia (ie, return to standing position) decreased from 103 minutes to 35.7 minutes after phenobarbital. These effects were attributed to an increase in the metabolic clearance of thiopental, as a result of induction of liver enzyme activity by phenobarbital. These results suggested that hepatic metabolism, in addition to distribution, is a factor that must be considered when assessing the difference in drug disappearance rates between Greyhounds and other breeds of dogs.
Probenecid infusion in mares: Effect on para-aminohippuric acid clearance
Authors: Gronwall Ronald , Brown Murray P.
Published: February 2025

Para-aminohippuric acid (paha, 0.1 mg/min/kg of body weight) was infused iv into 2 mares, followed by concurrent iv infusion of paha and probenecid (0.075, 0.15, 0.25, or 0.35 mg of probenecid/min/kg). Probenecid infusion reduced the clearance of paha at serum probenecid concentrations > 55 μg/ml. At 12-hour intervals, probenecid (in 5 repeated doses - 50, 75, 100, or 200 mg/kg) was administered by gavage to 2 mares. Mean serum probenecid concentration was > 55 μg/ml for all dosages. At dosages < 200 mg/kg, accumulation of probenecid in the serum was minimal from the 1st to the 5th dose. At a dosage of 200 mg/kg, probenecid accumulated in the serum from the 1st to the 5th dose. Intragastric administration of 5 doses of probenecid (75 mg/kg) at 12-hour intervals to 6 mares reduced the clearance of paha by 50%. Bioavailability of probenecid was 117 and 102% for 2 mares after a single intragastric dose, compared with a single iv dose.
Spinal decompressive procedures and dorsal compartment injuries: Comparative biomechanical study in canine cadavers
Authors: Smith Gail K. , Walter Mary C.
Published: February 2025

Effects of decompressive procedures or dorsal injuries on flexion-extension, 4-point bending properties of the L-3 and L-4 motion segment in dogs were quantitated and compared. Hemilaminectomy did not significantly (P < 0.05) affect mechanical properties of the spine. Bilateral facetectomy caused a small increase in the range of motion and a 56% decrease in ultimate bending strength. Excision of the supraspinous and interspinous ligaments decreased the flexural stiffness of the spine, increased the range of motion of the interspace, and decreased ultimate flexion bending strength 62%. Dorsal laminectomy caused a marked decrease in spine stiffness in all phases of flexion and extension, increased the range of motion, and decreased ultimate flexion bending strength 75%. Seemingly, a hemilaminectomy was preferable to the dorsal laminectomy if adequate decompression and exploration were achieved with the hemilaminectomy.
Neutralization of porcine transmissible gastroenteritis virus by complement-dependent monoclonal antibodies
Authors: Woods R. D. , Wesley R. D. , Kapke P. A.
Published: February 2025

Monoclonal antibodies (mab) to each of the 3 major structural proteins of transmissible gastroenteritis virus (tgev) of swine were compared, using their virus-neutralizing (vn) activity in the presence or absence of guinea pig, rabbit, or swine complement. The mab against the peplomer protein had similar vn titers for tgev in the presence or absence of complement from any source. The mab against the matrix protein had vn activity for tgev only in the presence of complement, whereas mab specific for the nucleocapsid protein did not possess vn activity in the presence or absence of complement. Serum from sows containing antibodies against tgev peplomer and matrix proteins had slightly higher vn titers in the presence of complement than in the absence of complement. High concentrations of complement from swine serum (128 U) had little effect on the infectivity of tgev for swine testes cells, whereas 32 U of complement from rabbit serum and 64 U of complement from guinea pig serum were able to neutralize virulent and attenuated tgev in the absence of known antibodies for tgev. Complement (≤ 8 U) from any source did not decrease the infectivity of tgev by > 0.5 log10 units.
Effects of mizoribine on canine renal allograft recipients
Authors: Gregory C. R. , Gourley I. M. , Haskins S. C. , Cain G. R. , Ishizaki G. , Cowgill L. D. , Willits N. H. , Patz J. D.
Published: February 2025

Heterotopic renal allograft transplantation and bilateral nephrectomies were performed on 12 mixed-breed dogs. Histoincompatibility was confirmed by serologically defined and lymphocyte-defined antigen testing. Mizoribine (5 mg/kg, q 24 h) was administered orally starting the day of surgery. Body weights, blood cell counts, serum biochemical and electrolyte values, immunoglobulin concentration, and serum mizoribine concentrations were determined. Complete urinalyses, including bacteriologic culturing and lymphocyte stimulation assays were performed.

The mean survival time for the allograft recipients was 20 ± 14 days; significantly longer than nontreated historic controls surviving 8.1 ± 0.6 days (P = 0.0098). Death was attributed to the combined effects of renal allograft rejection and development of a mizoribine-dependent gastroenteritis. Serum mizoribine concentrations were greater in dogs undergoing rapid allograft rejection because of compromised renal excretion of the drug. This resulted in a rapid onset of gastroenteritis. There were no complications resulting from infection, myelosuppression, or hepatotoxicosis.
Effect of naturally occurring intramammary infections by minor pathogens on new infections by major pathogens in cattle
Authors: Rainard Pascal , Poutrel Bernard
Published: February 2025

New mammary infections were recorded in 3 dairy herds during a lactation period by bacteriologic examination of milk samples at 3-week intervals. Influences of the infection status of quarters at the time of new infection and of microorganisms responsible for bacterial invasion were analyzed. The new infection rate in uninfected quarters was about 3 times the rate in quarters already harboring bacteria considered minor pathogens (coagulase-negative staphylococci and Corynebacterium bovis) or major pathogens (Staphylococcus aureus, streptococci). The frequency of new infections with major pathogens was almost halved by preexisting infections with minor pathogens (P = 0.05), mainly because of coagulase-negative staphylococci (P = 0.05) and, to a lesser extent, C bovis (P = 0.19). New infections by minor pathogens also were less frequent in quarters harboring a major pathogen (P < 0.05), indicating that the competition or antagonism between mammary infections was a general phenomenon.
Reduction of the ventricular arrhythmogenic dose of epinephrine by ketamine administration in halothane-anesthetized cats
Authors: Bednarski Richard M. , Sams Richard A. , Majors Lynda J. , Ashcraft Susan
Published: February 2025

The effect of ketamine administration on the ventricular arrhythmogenic dose of epinephrine (vade) was studied in 4 halothane-anesthetized cats. Each cat was anesthetized 4 times, 1 week apart, with halothane (end-tidal concentration, 1.5%) and with halothane (end-tidal concentration, 1.5%) combined with ketamine infusion (50, 100, and 200 μg/kg of body weight/min). Epinephrine was infused in progressively increasing doses. The vade (μg/kg) was calculated as the product of infusion rate of epinephrine and time of infusion necessary to induce 4 or more ventricular premature depolarizations within 15 s. The mean (± sd) vade during halothane anesthesia was 1.1 (± 0.30) μg/kg. Ketamine infusion significantly (P < 0.01) lowered the vade independently of dose. The dose of epinephrine (μg/kg) that induced an ecg change in P-wave configuration was calculated similarly. Less epinephrine was necessary to induce a change in P-wave configuration than was necessary to induce 4 or more ventricular premature depolarizations within 15 s.

Blood samples were collected after 4 hours of ketamine infusion and again immediately after determination of the vade for analysis of plasma ketamine and norketamine concentrations by use of gas chromatography. Plasma ketamine and norketamine concentrations after a 4-hour infusion and immediately after determination of the vade were similar for any given ketamine infusion rate, indicating that steady-state plasma concentrations had been reached for each infusion rate.

Blood pressure and heart rate were measured immediately before (base line) and immediately after infusion of the vade. Ketamine infusion significantly (P < 0.05) lowered base-line blood pressure, but not heart rate. Blood pressure and heart rate associated with the vade increased from base-line values, regardless of the ketamine infusion rate. These results suggested that ketamine administration lowers the vade in halothane-anesthetized cats.
Immunogenic effects of culture-derived exoantigens of Cooperia punctata on calves before and after challenge exposure with infective larvae
Authors: Leland Stanley E. , Sofield William L. , Minocha Harish C.
Published: February 2025

The parasitic stages of Cooperia punctata were cultivated in vitro, and the incubation fluid from these stages containing exoantigen (ExoAg; metabolites, secretions, excretions) was diafiltered (retaining material of approximate molecular weight > 10,000), concentrated, and lyophilized. Using serum of calves immune to C punctata, ExoAg activity was verified by agar gel immunodiffusion. The ExoAg was combined with adjuvants and was inoculated into calves. Results of preliminary experiments indicated that the ExoAg had potent biological activity capable of inducing severe respiratory distress and death. Subsequently, however, improved inoculation procedures and combination of ExoAg with aluminum hydroxide gel or Freund complete adjuvant consistently prevented this reaction in 25 calves. In helminth-free calves, the ExoAg induced marked eosinophilia, which generally was greater during the ExoAg-exposure period than after challenge exposure with infective larvae.

Of 27 calves exposed to the various ExoAg inoculation schedules, 12 had nematode reductions > 80%, 10 had < 16% reduction, and 5 had reductions between 39 and 72%. This polarization of the nematode recovery data generally thwarted statistical difference in overall consideration of all ExoAg inoculation schedules.

Additional manifestations of resistance, ie, prolonged prepatent period, reduced patent period, reduced number or lack of nematode eggs passed in feces, and reduced nematode length, were observed in calves of certain ExoAg inoculation schedules.

In vitro blastogenic response of blood lymphocytes was observed in calves exposed to ExoAg. Quantitatively, this cell-mediated immune response to ExoAg was as great as or greater than that after subsequent challenge exposure with infective larvae.

Intradermal inoculation of ExoAg into a calf resistant to C punctata induced delayed-type hypersensitivity. However, this reaction to ExoAg was not observed in nonimmunized, helminth-free calves used as controls.

Humoral antibodies against ExoAg were detected by an agar gel immunodiffusion test. Calves exposed to ExoAg always seroconverted and usually remained seropositive until necropsy. There were no false-positive results; however, ExoAg did not consistently coprecipitate (by agar gel immunodiffusion) with serum from infected calves that were not exposed to ExoAg.
Pharmacokinetics and bioavailability of ceftriaxone administered intravenously and intramuscularly to calves
Authors: Soback S. , Ziv G.
Published: February 2025

Ceftriaxone was administered to Israeli-Friesian male calves by iv and IM routes. The antibiotic was administered iv (10 mg/kg) to 10 calves and im to 23 calves; 8 were given the antibiotic at the rate of 10 mg/kg of body weight, 5 were given 20 mg/kg, and 10 were given 10 mg/ kg, together with probenecid at 40 mg/kg. Serum concentration vs time profiles measured after iv and im administration were analyzed by use of statistical moment theory.

The following mean values ± sd were found: elimination half-life (t½) was 83.8 ± 8.6 minutes after iv administration and significantly longer 116.8 ± 20.5 minutes (P < 0.001) after im administration at 10 mg/kg. The t½ was increased to 141.3 ± 24.4 minutes by the coadministration of probenecid and to 145.0 ± 48.2 minutes by doubling the im dosage to 20 mg/kg. The total body clearance was 3.39 ± 0.42 ml/min/kg and the renal clearance 2.37 ± 0.74 ml/min/kg. The specific volume of distribution was 0.2990 ± 0.0510 L/kg. The average mean residence time (mrt) was 94.0 ± 12.3 minutes after iv administration and 137.6 ± 19.9 minutes after im administration of ceftriaxone at 10 mg/kg. The mrt was increased to 198 ± 48.8 minutes by the coadministration of probenecid and to 191.0 ± 59.4 minutes by doubling the im dose. The former value was significantly different from the mrt after im administration of the antibiotic at 10 mg/kg. Bioavailability of ceftriaxone after im administration at 10 mg/kg and at 20 mg/kg was 78% and 83%, respectively.

The serum protein binding of ceftriaxone was concentration-dependent, being 76.9, 36, and 20% bound at serum drug concentrations of 2, 10, and 50 μg/ml, respectively.

The minimal inhibitory concentrations (mic90) of ceftriaxone for 90% of the isolants were 0.03 μg/ml for 140 Escherichia coli and 0.06 μg/ml for 188 Salmonella isolants tested, including group B Salmonella. The mic90 value for 22 Pasteurella isolants was 0.20 μg/ml. Serum drug concentrations remained much greater than the mic90 values during a 10-hour sampling period.
Radioimmunoassay for etorphine in horses with a 125I analog of etorphine
Authors: Tai Chen L. , Wang Chang-jin , Weckman T. J. , Popot Marie Agnes , Woods W. E. , Yang Jyan-Ming , Blake Jerry , Tai H. H. , Tobin Thomas
Published: February 2025

To improve the sensitivity and specificity of screening for etorphine in horses, an 125I-labeled etorphine analog was synthesized and an antibody to etorphine was raised in rabbits. A radioimmunoassay (ria) for etorphine was developed, using these reagents.

Bound and free 125I-labeled etorphine was separated by a double-antibody method that reduced interference from materials associated with equine urine. The 125I-labeled etorphine binding was rarely > 250 pg of background etorphine equivalents/ml in raw urine and was 100 pg/ml in hydrolyzed urine. The 125I-ria was capable of detecting etorphine equivalents in urine above these background values.

Etorphine equivalents were detected in equine urine samples for about 7 days after 4 mares were dosed with 0.22 μg of etorphine/kg of body weight, iv. The stability of etorphine in urine from these mares was evaluated. Urine from these dosed mares was held in constant − 20 C storage, and aliquots were repeatedly frozen and thawed. When analyzed for etorphine equivalents using an 125I-ria, etorphine and its metabolites in urine samples were stable for ≤ 38 days if continuously frozen and also resistant to repeated freezing and thawing.
A technique for catheterization of the equine antebrachiocarpal joint
Authors: Lloyd K. C. Kent , Stover Susan M. , Pascoe John R. , Pool Roy R.
Published: February 2025

A 2.5-cm long, 0.8 mm in diameter catheter was placed percutaneously into the palmarolateral pouch of the antebrachiocarpal joint in 6 clinically normal horses. The catheter was affixed in place for 72 hours. Cytologic analysis was performed on synovial fluid specimens obtained through the catheter at postcatheterization hours (pch) 0, 24, and 72. The horses were euthanatized at pch 72, and macroscopic and microscopic examinations were performed on the dorsal portion of the joint capsule and the palmarolateral pouch of the catheterized and contralateral (noncatheterized) joint.

Clinical, synovial fluid cytologic, and synovial membrane histologic examinations were performed to assess the effect of the catheter on clinically normal equine synovial membrane. Serially obtained synovial fluid specimens were yellow and clear or hazy and had good mucinous precipitate quality at all times in all horses, except 2, in which the catheter required readjustment. Mean refractive index was slightly decreased, and the rbc count was high at pch 24 and 72, compared with pch 0; the highest rbc count was 12,550 cells/μl (pch 24). Statistically significant (P < 0.05) increases were observed in wbc, neutrophil, and large and small mononuclear cell counts between pch 0 and 72. These increases were modest, except the mean wbc count (51,000 cells/μl, pch 72) observed in 1 horse in which the catheter was dislodged, requiring reinsertion into the joint. At necropsy, subcutaneous hemorrhages were observed at the catheter insertion site in all horses. The synovial membrane of the catheterized joint was discolored (ranging from yellow-orange to salmon), compared with the contralateral synovium (noncatheterized joint). The synovial inflammation was mild in 5 of 6 catheterized joints; in each instance, the palmarolateral pouch was more inflamed than was the dorsal portion of the joint capsule. Edema, small mononuclear cells, and a few scattered neutrophils were observed in the subintima of the synovial membrane. In 1 horse, a marked inflammatory reaction characterized by a predominance of neutrophils, was observed in the synovium.
Duration of immunity and efficacy of an oil emulsion Escherichia coli bacterin in cattle
Authors: Collins Neil F. , Halbur Thomas , Schwenck William H. , Hoogeveen Polly , Pierce Ralph L. , Behan R. Wayne , Pankratz Duane
Published: February 2025

An oil emulsion Escherichia coli bacterin administered in 1- and 2-dose vaccination regimens was evaluated in beef cattle. Serologic responses to the K99 pilus antigen were monitored, and suckling offspring from vaccinated and nonvaccinated cows were inoculated with virulent, K99-positive, enterotoxigenic Escherichia coli. The degree of protection and duration of immunity conferred were determined in 2 respective studies.

In the first study (study A), titers of pregnant cattle were determined from time of vaccination through calving (a 6- to 20-week period). Titers of 24 cows vaccinated with a single 2-ml dose of bacterin were compared with those of 24 cows given a 2-dose regimen and with those of 23 nonvaccinated cattle (contemporary controls).

Inoculum consisting of 1.2 × 1012 viable enterotoxigenic E coli/dose administered to nursing calves from these dams yielded 0% mortality (0 deaths/20 calves) in calves from 1-dose vaccinates, 6% mortality (1 death/18 calves) in calves from 2-dose vaccinates, and 37% mortality (7 deaths/19 calves) in calves from nonvaccinated dams.

Study B was an extended evaluation conducted in cattle that were kept in the study up to 87 weeks from initial vaccination until calving. Serologic titers to the K99 pilus antigen were compared in 1-dose, 2-dose, and nonvaccinated cattle in groups of 8, 6, and 6, respectively. Calves from these dams were inoculated with 8.1 × 1011 viable enterotoxigenic E coli/dose, which resulted in 0% mortality (0 deaths/5 calves) in calves from 1-dose vaccinates, 0% mortality (0 deaths/5 calves) in calves from 2-dose vaccinates, and 80% mortality (5 deaths/6 calves) in calves from nonvaccinated dams.
Effects of xylazine on cecal mechanical activity and cecal blood flow in healthy horses
Authors: Clark E. Susan , Thompson Sidney A. , Becht James L. , Moore James N.
Published: February 2025

Mechanical activity of the cecal body, lateral cecal arterial blood flow, carotid arterial pressure, and heart rate were measured in 6 conscious healthy horses 30 minutes before and for 120 minutes after iv administration of xylazine at dosages of 1.1 mg/kg of body weight, 0.55 mg/kg, and 0.275 mg/kg. Xylazine at a dosage of 1.1 mg/kg reduced the mean motility index (the product of the mean amplitude of contractions and the total duration of contractile activity divided by the recording time) of the circular and longitudinal muscle layers for the first, second, third, and fourth 30-minute periods after administration of xylazine. Xylazine at a dosage of 0.55 mg/kg reduced the motility index of the circular and longitudinal muscle layers for the first and second 30-minute periods after administration of xylazine. Xylazine at a dosage of 0.275 mg/kg reduced the motility index of the circular and longitudinal muscle layers for the first 30-minute period after administration of xylazine. Mean lateral cecal arterial blood flow was significantly (P < 0.05) lower than the base-line value at 2 and 4 minutes after administration of all 3 xylazine dosages and at 8 minutes after administration of xylazine dosages of 1.1 mg/kg and 0.55 mg/kg. All dosages of xylazine caused transient hypertension and bradycardia, followed by hypotension.
Strains of Escherichia coli associated with urogenital disease in dogs and cats
Authors: Wilson Richard A. , Keefe Thomas J. , Davis Michael A. , Browning Marcia T. , Ondrusek Kenneth
Published: February 2025

Selected strains of Escherichia coli associated with urogenital disease in dogs and cats were evaluated for 3 virulence factors associated with human uropathogenic strains. Urogenital strains of E coli from dogs and cats had high prevalence of α hemolysin and were clustered in 5 to 10 somatic serogroups, attributes also shared by human uropathogenic strains. However, the canine and feline urogenital strains failed to have increased prevalence of mannose-resistant hemagglutination, as has been reported for human uropathogenic strains.
Ultrastructural and electrophoretic analysis of Treponema hyodysenteriae axial filaments
Authors: Miller D. P. , Toivio-Kinnucan M. , Wu G. , Wilt G. R.
Published: February 2025

Axial filaments of Treponema hyodysenteriae were purified and examined by transmission electron microscopy. The size and fine structure of the filaments were similar to those of Treponema zuelzerae and Treponema phagedenis biotype reiterii. Filaments were dissociated by heat and 2-mercaptoethanol and examined by polyacrylamide-gel electrophoresis. Six protein bands were evident, with approximate molecular weights of 39,000, 29,000, 27,000, 22,000, 21,000, and 18,500 daltons. All the proteins reacted with T hyodysenteriae and T innocens rabbit antisera, using the immunoblot technique.
Protection of mice and swine from pseudorabies virus-induced mortality by administration of pseudorabies virus-specific mouse monoclonal antibodies
Authors: Marchioli Carmine , Yancey R. J. , Timmins J. G. , Post L. E. , Young B. R. , Povendo D. A.
Published: February 2025

Hybridomas were selected for secretion of monoclonal antibodies directed against pseudorabies virus (prv) glycoproteins. Each monoclonal antibody was capable of neutralizing prv in vitro in the presence of complement. This panel of antibodies was used in passive immunization studies to protect mice and swine from prv-induced mortality. The most protective antibody in mice was 3A4, specific for prv glycoprotein gp50, which afforded as high as 100% protection. Although antibody 3A4 was partially protective in swine, antibody 3D11, which is specific for prv glycoprotein glll, afforded greater protection—83% protection when ascitic fluid was used and 100% protection when immunoglobulin concentrated from cell cultures was used at a dose of 150 mg/pig. These studies demonstrated that monoclonal antibodies may be useful for short-term prophylaxis against prv-induced disease and that antibody directed against either prv glycoprotein glll or gp50 is sufficient to protect animals from prv-induced mortality.
Activity of febantel on natural infections of gastrointestinal helminths in lambs in a controlled test
Authors: Lyons E. T. , Drudge J. H. , Tolliver S. C.
Published: February 2025

The efficacy of febantel paste formulation (6 and 12 mg/kg) against natural infections of gastrointestinal helminths in lambs (n = 33) in Kentucky was evaluated in a controlled test. For the test, 23 lambs were treated orally (17 at 6 mg/kg and 6 at 12 mg/kg) and 10 lambs were not treated. Removals at both dosages in treated lambs were 95% to 100% for species of immature and mature Haemonchus, Trichostrongylus, and Cooperia; and mature Ostertagia females, Nematodirus, and Strongyloides. For immature Nematodirus, removals were 92% and 77% at the dosages of 6 and 12 mg/kg, respectively. Only a few specimens (av < 100) of some other species or stages were found in the nontreated group and removal of them (at both dosages) were 94% to 100% for Ostertagia (immature and males), Strongyloides (immature), Oesophagostomum (immature), and Moniezia (mature); and 61% (at 6 mg/kg) and 100% (at 12 mg/kg) for Capillaria (mature), 0% for Trichuris (mature, at both dosages), and 67% (at 6 mg/kg) and 100% (at 12 mg/kg) for Oesophagostomum (mature).
Lesions in transplacentally induced toxoplasmosis in goats
Authors: Dubey J. P.
Published: February 2025

Fifteen pregnant does were inoculated orally with 10 to 1,000 oocysts of the GT-1 strain of Toxoplasma gondii. Two does were euthanatized on postinoculation days (pid) 10 and 14, and the remaining 13 does aborted or delivered kids transplacentally infected with T gondii on pid 9 to 65. Tissues of all 34 fetuses or kids from the inoculated does were examined for gross and microscopic lesions. Placental necrosis and encephalomyelitis were the most prominent lesions. Toxoplasma gondii invaded the fetal placenta between pid 9 and 11 and invaded fetal tissues 2 to 3 days later. Necrosis attributed to toxoplasmosis, confined to cotyledons, was found in all placentas examined on pid 18. Encephalomyelitis was found in most fetuses or kids between pid 30 and 65. Lesions in fetal tissues were sparse. Because T gondii is rarely found in lesions, histologic examination of the fetal tissues is not likely to help in diagnosing every case of transplacentally induced toxoplasmosis in goats.