bluuebunny/crossref_metadata_2025 huggingface dataset:
Transposon mutagenesis in Bordetella avium
Authors: Leyh Randy D. , Griffith Ronald W. , Arp Lawrence H.
Published: February 2025

Transpooson mutagenesis was used to introduce specific mutations in the chromosome of Bordetella avium. The transposon Tn5 was transferred by conjugation to B avium from Escherichia coli strain SM10 by the suicide plasmid vector pSUP1011. A defined minimal medium for growth of B avium was developed for scoring transposon-containing mutants for specific nutritional requirements. Approximately 1% of all mutants tested were auxotrophic in some form, and these organisms were grouped into 13 classes. Also, 2 classes of hemagglutination-negative mutants were isolated. Stability of Tn5 insertion was examined, and frequencies of reversion < 10−7 were observed, indicating stable mutations.
Adherence of Bordetella avium to tracheal mucosa of turkeys: Correlation with hemagglutination
Authors: Arp Lawrence H. , Leyh Randy D. , Griffith Ronald W.
Published: February 2025

Adherence to turkey tracheal mucosa and agglutination of guinea pig erythrocytes were determined for 20 strains of Bordetella avium. Ten type-I strains, 7 type-II strains, 2 transposon-induced mutants, and 1 revertant were evaluated. All type-I strains adhered readily to tracheal mucosa and agglutinated erythrocytes, whereas no type-II strains adhered to trachea or caused hemagglutination (ha). Two mutants selected for loss of ha activity were less adherent to tracheal mucosa, compared with the parent strain. Reversion of one mutant to ha-positive status was accompanied by reconstitution of much of its adherence capacity. Results of this study provide preliminary evidence that tracheal adherence and ha of B avium are closely related.
Procoagulant activity in respiratory tract secretions from horses with chronic pulmonary disease
Authors: Grünig G. , Hermann M. , Winder C. , Von Fellenberg R.
Published: February 2025

Cell-free supernatants (sol phases), obtained after centrifugation (50,000 × g for 45 minutes) of respiratory tract secretions from horses with chrome pulmonary disease, were assayed for procoagulant activity (pca) in a one-stage clotting assay. Of the 103 specimens tested, 59% (61) contained pca. Procoagulant activity was detected most often in respiratory tract secretions of severely affected horses and was correlated with the quantity of neutrophils in the respiratory tract secretions. In 12 of the 17 secretions tested, the clotting time was decreased in a dose-dependent manner. However, in the coagulation assay, some reversal of pca or inhibition of coagulation was observed in 4 secretion specimens when greater volumes of sol phase were added. Procoagulant activity was characterized tentatively as tissue factor, because it was temperature stable and was inhibited by phospholipase C and by concanavalin A. Clotting was induced in factor VIII-deficient human plasma; however, with the exception of 1 respiratory secretion specimen, clotting was not enhanced in factor VII-deficient human plasma.

Procoagulant activity is a useful indicator of airway inflammation.
Characterization of bovine herpesviruses isolated from six sheep and four goats by restriction endonuclease analysis and radioimmunoprecipitation
Authors: Whetstone Cecelia A. , Evermann James F.
Published: February 2025

Viral dna from 10 herpesviruses isolated from 6 sheep and 4 goats were examined by restriction endonuclease analysis with respect to their relatedness to one another; to bovine herpesvirus type 6 (bhv-6), also known as caprine herpesvirus; and to 2 strains of bovine herpesvirus type 1 (bhv-1), known as infectious bovine rhinotracheitis virus (ibrv) and infectious pustular vulvovaginitis virus (ipvv). Viral proteins from the isolates were examined by radioimmunoprecipitation with anti-bhv-1/ibrv gnotobiotic calf (bovine) serum, anti-bhv-1/ibrv bovine hyperimmune serum, and anti-bhv-6 rabbit serum to evaluate their antigenic relatedness to each other. The goat isolates were obtained from animals with various disease conditions including respiratoiy tract disorders, vulvovagnitis, and wart-like lesions on the eyelid. The other isolates were from domestic sheep and came from aborted fetuses or from sheep with fatal pneumonia or proliferative lesions around lips and nose. All of the goats and 4 of the sheep from which the viral isolates were obtained had comingled with cattle.

Purified dna from each of the 10 field isolates and from bhv-1/ibrv, bhv-1/ipvv, and bhv-6 caprine herpesvirus was cleaved with restriction endonuclease Pst I. Five of 6 sheep isolates and 3 of 4 goat isolates yielded unique restriction patterns, ie, patterns that differed from each other by one or more bands. Sheep isolate dna patterns were different from goat isolate patterns, and all restriction endonuclease analysis patterns were similar to the pattern for bhv-1/ibrv, but different from that for bhv-1/ipvv or for bhv-6. Restriction patterns from 3 sheep and 2 goat isolates were indistinguishable from patterns previously reported for 3 modified-live ibrv vaccines.

35S-Labeled viral proteins from all of the goat isolates were immunoprecipitated by the anti-bhv-1/ibrv sera. Two of the isolates reacted slightly with the anti-bhv-6 serum. Three of the sheep isolates were immunoprecipitated only by anti-bhv-1/ibrv sera; however, the 3 remaining sheep isolates were immunoprecipitated not only by anti-bhv-1/ibrv sera, but also by the anti-bhv-6 serum, thus appearing to be antigenically related to bhv-6 caprine herpesvirus.
Effects of vaccination of calves against induced Haemophilus somnus pneumonia
Authors: Groom S. C. , Little P. B.
Published: February 2025

The efficacy of a killed whole-cell Haemophilus somnus bacterin against induced H somnus pneumonia was examined in 10-week-old male calves. Twenty calves were assigned to 1 of the 3 following groups: group 1, nonvaccinated controls (n = 4); group 2, vaccinated once (n = 8); and group 3, vaccinated twice 14 days apart (n = 8). The serum antibody response to vaccination and challenge exposure was evaluated by the bacterial agglutination test and solid-phase immunoassay (spia).

Vaccinating calves twice, 14 days apart, significantly (P < 0.05) reduced the severity of clinical signs of pneumonia and gross lesions. Deaths occurred in 1 of 4 nonvaccinated controls, 1 calf vaccinated once, and none of the calves vaccinated twice, 14 days apart. Postvaccination bacterial agglutination titers measured 14 days after the final vaccination were not significantly different between groups 2 and 3, but spia titers were significantly (P < 0.05) higher in groups 2 and 3, compared with those in group 1. The less severe clinical signs of pneumonia observed in group-3 calves, compared with those in calves in groups 1 and 2, were significantly (P < 0.01) correlated to higher spia titers, indicating the protective value of vaccinating twice.
Comparative nephropathogenicity of infectious bronchitis virus in bursectomized and nonbursectomized chickens
Authors: Chandra Manik
Published: February 2025

A study was conducted to compare the responses of bursectomized (Bx) and nonbursectomized (non-Bx) specific-pathogen-free male chickens to Australian T strain of infectious bronchitis virus. Four chickens from each group were killed at 3, 5, 7, 14, 21, and 28 days after conjunctival inoculation of the virus. Clinical signs and gross and microscopic lesions were more severe in Bx than in non-Bx chickens. The non-Bx chickens had linear IgG deposits along the renal tubules. Virus-neutralizing titers were log10 2.74 to 4.33 for non-Bx chickens and less than log10 1.25 for the inoculated Bx and for broth-inoculated Bx and non-Bx chickens (controls). Early in the disease, renal lesions were of the same type in all infected chickens, but, were more severe in Bx chickens. Later, nephritis was chronic and active in Bx chickens and was chronic in non-Bx chickens.
Effect of transportation stress on bronchoalveolar lavage fluid analysis in female horses
Authors: Traub-Dargatz J. L. , McKinnon A. O. , Bruyninckx W. J. , Thrall M. A. , Jones R. L. , Blancquaert A-M. B.
Published: February 2025

Four bronchoalveolar lavages were performed sequentially on 9 control and 8 transport-stressed female horses. Alterations in results of fluid cytologic analyses, microbial content, and phagocyte function of recovered pulmonary macrophages in all horses were determined. Seemingly, absolute and relative increase in the number of inflammatory cells detected in the second bronchoalveolar lavage fluid of control horses was the result of irritation of the first lavage. This increased response was not observed in transport-stressed horses until 5 days after transport (third lavage; 10 days after initial lavage). Seemingly, delayed inflammatory response was the result of the transport stress. Microbial content and macrophage function were not significantly different between the 2 groups (P > 0.05).
Effects of flunixin meglumine on jejunal blood flow, motility, and oxygen consumption in ponies
Authors: Stick J. A. , Arden W. A. , Chou C. C. , Parks A. H. , Wagner M. A. , Johnston C. C.
Published: February 2025

Using isolated autoperfused intestinal segments, the effects of flunixin meglumine administration on systemic arterial blood pressure, jejunal blood flow, vascular resistance, motility, arteriovenous oxygen difference, and oxygen consumption were determined in 10 anesthetized ponies ventilated with a mixture of halothane and oxygen. Saline solution or flunixin meglumine (1.1 mg/kg of body weight) was infused as a single bolus into the left jugular vein. By 10 minutes, flunixin meglumine increased systemic arterial blood pressure and increased intestinal vascular resistance. The jejunal blood flow,, however, was not significantly decreased until 1 hour after flunixin meglumine administration. Intestinal motility, arteriovenous oxygen difference, and oxygen consumption were unchanged. Results indicated that acute administration of flunixin meglumine increases systemic arterial pressure and intestinal vascular resistance, but the resulting intestinal vasoconstriction does not lead to compromise of intestinal viability.
Effects of intracisternal bead devices on lacteal secretion components, plaque formation, and bacterial infection during the nonlactating period
Authors: Nickerson Stephen C. , Thompson William J. , Oliver Stephen P. , Akers R. Michael
Published: February 2025

Effects of placing intracisternal bead devices (icb) into teat cisterns of 6 dairy cows, from the end of lactation through parturition, were studied. Lacteal secretion samples were collected weekly from each mammary quarter during the nonlactating period to monitor composition changes in icb-fitted and nonfitted quarters. In quarters remaining uninfected (n = 15), there were significantly higher mean somatic cell counts (P < 0.05), percentage of neutrophils (P < 0.019), and cell viability (P < 0.038), but significantly lower percentage of macrophages (P < 0.013) in icb-fitted quarters compared with those in nonfitted quarters. The icb had no significant effect on mean weekly values for percentage of lymphocytes, pH, lactoferrin, citrate, citrate/lactoferrin molar ratio, serum albumin, α-lactalbumin, and N-acetyl-β-d-glucosaminidase. In infected quarters (n = 9), pH of mammary secretions was significantly (P < 0.004) higher in icb-fitted quarters, but concentrations of lactoferrin (P < 0.004), α-lactalbumin (P < 0.013), and N-acetyl-β-d-glucosaminidase (P < 0.028) were significantly lower, compared with those in nonfitted quarters. Coagulase-negative staphylococci comprised approximately 90% of all infections. Over the nonlactating period, 16.4 and 41.5% of samples from nonfitted and icb-fitted quarters, respectively, contained coagulase-negative staphylococci. Microscopic examination of icb from uninfected quarters revealed a thin coating of plaque with adhering neutrophils, macrophages, and multinucleated giant cells. Microscopic examination of plaque on devices from icb-fitted quarters harboring coagulase-negative staphylococci revealed numerous adherent cocci and neutrophils.
Cell-mediated immune responses of suckling pigs inoculated with attenuated or virulent transmissible gastroenteritis virus
Authors: Welch Siao-Kun W. , Saif Linda J. , Ram Sumita
Published: February 2025

Two litters of suckling pigs seronegative for transmissible gastroenteritis (tge) virus were orally inoculated with live attenuated (P115) or virulent (M5C) strains of tge virus. A third seronegative litter (controls) was given cell culture fluids from uninfected cells. Lymphocytes were collected from blood, spleen, mesenteric lymph nodes, and Peyer patches of euthanatized pigs at 0 day and approximately weekly until 26 days after exposure and at approximately 45 days after exposure. Sera were tested for virus-neutralizing antibody titers by use of plaque reduction. Lymphocytes were tested in a lymphocyte proliferation assay for uptake of [3H]thymidine after incubation with the homologous or the heterologous strain of inactivated tge virus or uninfected cell culture fluids. Only pigs inoculated with virulent tge virus developed clinical signs of tge and shed virus. However, all pigs inoculated with tge virus seroconverted at 6 days after exposure. Responses of lymphocytes from all sources from tge virus-inoculated pigs peaked between 6 and 14 days after exposure. Pigs inoculated with virulent tge virus had higher lymphocyte proliferative responses and neutralizing antibody titers than did pigs inoculated with attenuated tge virus. Cessation of virus shedding coincided with the peak of lymphocyte proliferative responses. The highest responses were with intestinal lymphocytes (mesenteric lymph nodes and Peyer patches) from pigs inoculated with virulent tge virus. The responses of intestinal lymphocytes from pigs inoculated with attenuated virus were not significantly different from those of pigs inoculated with cell culture fluid. Lymphocytes collected from all sources, except blood from M5C-inoculated pigs, had significantly (P < 0.05) higher responses to the homologous than to the heterologous tge virus stimulation. Lymphocytes collected from blood of P115-inoculated pigs had significantly (P < 0.05) higher responses to the homologous antigen.
Consistent capacity for adrenocortical response to ACTH administration in pigs
Authors: Hennessy D. P. , Stelmasiak T. , Johnston N. E. , Jackson P. N. , Outch K. H.
Published: February 2025

The effect of acth administration on plasma cortisol concentrations in purebred and crossbred pigs was investigated. Pigs were given either 25 IU of acth or physiologic saline solution im. Blood samples were collected immediately before and 1 hour after acth or saline solution administration. Administration of acth resulted in a significant (P < 0.01) increase in plasma cortisol concentration compared with that resulting from administration of saline solution; mean values after acth administration were similar in both breed groups. In contrast, a fivefold range of differences was observed among individual pigs of the same age, sex, and body weight, irrespective of breed group.

The type and magnitude of the adrenocortical response was consistent and repeatable in pigs over a 3-month period, suggesting that pigs have a consistent capacity for adrenocortical response to acth administration. Development of a dynamic test allowed the high and low responding extremes in a population to be detected. The most suitable dose of synthetic acth was established to be 50 IU, and the best time for blood sample collection was 60 minutes after acth administration. The classification of individual pigs as high or low responders was repeatable and was not affected by prior short-term exposure to acth.
Effects of age and season on the type and occurrence of sperm abnormalities in Nubian bucks
Authors: Skalet L. H. , Rodrigues H. D. , Goyal H. O. , Maloney M. A. , Vig M. M. , Noble R. C.
Published: February 2025

Effects of age and season on type and occurrence of sperm abnormalities were examined in semen samples collected from 3 groups of Nubian bucks at ages of 4 to 9 months, 10 to 21 months, and 39 to 50 months. The average total percentage of sperm abnormalities at the onset of puberty (141 ± 4 days) was 64.6 ± 14.8% (head, 19.5 ± 13.6%; middle piece, 17.2 ± 9.3%; and proximal protoplasmic droplets, 14.6 ± 10.5%), but this improved rapidly and was reduced to 12.5 ± 7.5% by 8 months of age (head, 1.9 ± 4.5%; middle piece, 4.6 ± 2.8%). Further increase in age, at least up to 4 years, did not reveal a significant effect (P < 0.05) on the type or percentage of total abnormalities. Similar to age, a comparison of data among seasons did not reveal a significant effect on the type or occurrence of sperm abnormalities in 10- to 21-month-old or 39- to 50-month-old bucks. Seemingly, Nubian bucks started producing good quality semen at 8 months of age, and season did not influence sperm abnormalities.
Combined effects of fasting and diet on interferon production and virus replication in calves infected with a vaccine strain of infectious bovine rhinotracheitis virus
Authors: d'Offay Jean M. , Rosenquist Bruce D.
Published: February 2025

A study was undertaken to investigate the combined effects of fasting and different diets on interferon (ifn) production and virus replication measured in nasal secretions of calves inoculated with a vaccine strain of infectious bovine rhinotracheitis virus. Four groups of calves were inoculated intranasally with infectious bovine rhinotracheitis virus. Two groups were inoculated 24 hours after onset of a 3-day fast; upon refeeding, 1 group was fed a maintenance diet (M diet) of hay, and the other was fed a higher energy diet (he diet) of hay and concentrate. Nonfasted control groups were fed the M diet or the he diet. Overall ifn production was highest (P < 0.01) in nonfasted calves fed the M diet throughout the study and lowest in nonfasted calves fed the he diet. Fasted calves refed the he diet produced consistently and significantly more ifn than did nonfasted calves fed this diet. Fasted calves refed the M diet, however, produced significantly less ifn, compared with control calves fed the M diet throughout the study. Overall mean virus excretion was similar in all groups; therefore, the amount of virus replication per se did not account for the differences in ifn production, nor did greater ifn production result in less virus excretion. Serum cortisol concentrations and immune responses were not significantly affected by fasting or diet.
Toxicologic evaluation of chlorpyrifos in cats
Authors: Hooser Stephen B. , Beasley Val R. , Sundberg John P. , Harlin Karen
Published: February 2025

Twenty-four male domestic shorthair cats were used to evaluate the acute and chronic effects of a single, toxic but sublethal, orally administered dose of chlorpyrifos. A dosage of 10 mg/kg of body weight did not induce clinical signs of toxicosis, but a dosage of 40 mg/kg induced clinical signs of toxicosis, and 1 of 12 cats died. Chlorpyrifos given at a dosage of 0.1 mg/kg to 2 cats reduced whole blood and plasma cholinesterase (Che) activities to values obtained after cats were given doses that induced clinical signs of toxicosis. Regeneration time for whole blood and plasma Che activities ranged from 7 to 28 days. Brain Che activity was considerably decreased in 1 cat that died 4.5 hours after dosing, but was normal in all others at 28 days after dosing. Other than decreased Che activity, significant changes were not seen in hematologic or serum biochemical values. Toxin-related lesions were not seen during macroscopic or microscopic examination.
Differences in diagnostic test results and hematologic data between aged and young horses
Authors: Ralston Sarah L. , Nockels Cheryl F. , Squires Edward L.
Published: February 2025

Hematologic data and results of diagnostic tests were compared between aged (≥ 20 years old) and young (≤ 5 years old) horses to identify hematologic and metabolic changes associated with aging. Initial data were obtained from 8 aged and 6 young mares (group 1). Similar data were collected from a second group of aged (3 mares and 3 geldings) and young (1 mare and 5 geldings) horses (group 2). Dexamethasone suppression tests (dst) and necropsies were performed on 6 additional mares and mare 8 from group 1 (group 3).

Complete blood counts and serum biochemical profiles were compared between young and aged horses of groups 1 and 2. Mean corpuscular volume was higher (P < 0.05) in aged horses. Oral glucose tolerance and insulin response to orally administered glucose were measured in 13 aged horses (groups 1 and 2) and 6 young mares of group 1. In group 1, plasma ascorbic acid values were lower (P < 0.05) in aged horses than in young horses maintained under the same conditions and feeding regimens. An apparent age-related hyperinsulinemic response to orally administered glucose identified in group-1 mares was probably a result of a high occurrence of subclinical hypophyseal and/or thyroid adenomas. Of 13 aged horses necropsied (groups 2 and 3), 10 had hypophyseal and/or thyroid adenomas that, in group 2, were consistently associated (P < 0.05) with hyperinsulinemic responses to orally administered glucose. All horses in groups 2 and 3 were given a 24-hour dst. Failure to maintain suppression of serum cortisol values 24 hours after dexamethasone administration was correlated (P < 0.05) with the presence of hypophyseal and thyroid adenomas whether or not clinical signs were apparent. There were no apparent changes in oral glucose tolerance, insulin secretion, or dst attributable to aging alone. Seemingly, there were no age-related changes in serum biochemical profiles or cbc in aged horses other than an increase in mean corpuscular volume.
Effect of broiler chicken age on susceptibility to experimentally induced Cryptosporidium baileyi infection
Authors: Lindsay David S. , Blagburn Byron L. , Sundermann Christine A. , Giambrone Joseph J.
Published: February 2025

Clinical signs of respiratory tract disease were observed in chickens that were inoculated intratracheally with 1 × 106 oocysts of Cryptosporidium baileyi at 2 or 14 days of age (10 chickens/group), but not in chickens inoculated at 28 or 42 days of age (10 chickens/group). Orally inoculated chickens in all age groups (10 chickens/group) did not develop clinical signs of disease. Orally and intratracheally inoculated chickens in all age groups were infected, as determined by the finding of cryptosporidia in tissue sections of the trachea, bursa of Fabricius, and cloaca, and by the recovery of oocysts from their feces. Chickens inoculated at 2 and 14 days of age excreted oocysts for a longer period and had greater numbers of cryptosporidia in their tissues, compared with chickens inoculated at 28 and 42 days of age.
Force plate analyses before and after stabilization of canine stifles for cruciate injury
Authors: Budsberg S. C. , Verstraete M. C. , Soutas-Little R. W. , Flo G. L. , Probst C. W.
Published: February 2025

Ground reaction forces were measured from the hind limbs of 9 dogs before and after stabilization of unilateral cranial cruciate ligament rupture. Before surgery, peak vertical force, associated impulses, and weight distribution were significantly less (multivariate analysis P < 0.02) in the affected limb, compared with the clinically normal limb. Craniocaudal peak forces and impulses, divided into braking and propulsion, also were significantly less in the affected limb. At a minimum of 7 months after retinacular imbrication, all vertical and craniocaudal measurements in the affected limb were increased significantly. Significant changes were not found in the normal limb. Furthermore, at the postoperative evaluation, there was no significant difference in any measurement between the affected and normal hind limbs. The results indicated restoration of function in the cruciate-deficient limb when compared with the clinically normal hind limb at a walking gait during the study time period.
Effects of various sedatives on air cystometry in dogs
Authors: Johnson Cheri A. , Beemsterboer Jean M. , Gray Peter R. , Slusser Peter G. , Goullaud Eric L.
Published: February 2025

The effects of various sedatives on air cystometry in dogs were investigated. Oxymorphone plus acepromazine, xylazine alone, atropine plus xylazine, and diazepam plus ketamine were compared for interference with the detrusor reflex, adequacy of patient restraint, and development of adverse side effects. Atropine plus xylazine was the best of the 4 drug combinations tested, because it had the least interference with the detrusor reflex, bradycardia did not develop, and excellent restraint was obtained. Pain and hematuria were common whenever intravesicular pressure exceeded 40 cm of H2O, yet pressures that high were rarely necessary to stimulate the detrusor reflex.
Percutaneous biopsy of the proximal humeral growth plate in dogs
Authors: Breur G. J. , Slocombe R. F. , Braden T. D.
Published: February 2025

A percutaneous biopsy technique for the study of endochondral bone formation in the dog was developed. With the dogs under general anesthesia or sedated with a combination of a tranquilizer and a local anesthetic, biopsy specimens were obtained from the proximal growth plate of the humerus with the use of a Jamshidi bone biopsy needle. Biopsy specimens were structurally intact, and contained epiphysis, growth plate, and metaphysis. The procedure proved to be a simple, safe technique, which caused minimal discomfort for the patient and did not affect the growth of the proximal end of the humerus, even after multiple biopsies.
Efficacy of febantel against naturally acquired gastrointestinal nematodes in calves, and recognition of Oesophagostomum venulosum in Oregon cattle
Authors: Hoberg E. P. , Zimmerman G. L. , Rickard L. G. , Schons D. J.
Published: February 2025

The efficacy of febantel (5.0 mg/kg) against naturally acquired infections of gastrointestinal nematodes was evaluated in a controlled test in calves during the winter. Twenty steers were allotted to either control or treatment groups of 10 animals each. Seven days after treatment, calves were euthanatized and necropsied for recovery of parasites. Febantel was highly effective against adults of Ostertagia spp (88.6% efficacy based on median), Cooperia spp (97.7%), Trichostrongylus spp (98.2%), Oesophagostomum spp (100%), and Bunostomum phlebotomum (100%). Effects of treatment against adults of Nematodirus spp (100%) were not significant, whereas, degrees of infection of Strongyloides papillosus, Capillaria sp, and Trichuris sp were insufficient for evaluation. The activity of febantel was variable in controlling inhibited and late fourth-stage larvae of Cooperia spp (100% and 100%, respectively) and Ostertagia spp (−81.5% and 36.7%). Numbers of larval Nematodirus and Capillaria sp were insufficient for evaluation. Overall, febantel administered at 5.0 mg/kg reduced populations of adult and larval strongyles and other gastrointestinal nematodes in calves by 80.7% (P = 0.002). An unexpected finding during the trial was the recovery of Oesophagostomum venulosum from all control calves.
Evaluation of the stable fly (Stomoxys calcitrans) as a vector of enzootic bovine leukosis
Authors: Weber A. F. , Moon R. D. , Sorensen D. K. , Bates D. W. , Meiske J. C. , Brown C. A. , Rohland N. L. , Hooker E. C. , Strand W. O.
Published: February 2025

Experiments reported here were directed at 2 questions: (1) Can the stable fly {Stomoxys calcitrans) transmit enzootic bovine leukosis? (2) Could early viremia augment the probability of transmission by this insect? In one vector experiment, calves and bovine leukemia virus (blv)-infected cows were housed with and without stable flies. The calves were monitored serologically during a 3-month postexposure period, using the agar gel immunodiffusion test. All fly-infested and fly-free calves remained blv-seronegative.

For a second vector experiment, donor calves, newly injected with blood from blv-infected cows with high virus expression, were tethered alternately between uninoculated, weaned blv-seronegative calves. These groups were housed with or without flies in 2 replicate trials. The inoculated calves from the first replicate seroconverted at 16 and 23 days after inoculation; the inoculated calves from the second replicate seroconverted at 11, 16, 16, and 37 days after inoculation. All uninoculated calves remained blv-seronegative.

In a manual transmission experiment, 50 unfed stable flies were allowed to complete a meal on each of 3 blv-seronegative calves after feeding on a blv-seropositive cow with high (42%) virus expression. One control calf was injected with blood from the cow. Seroconversion occurred in the control calf and 1 calf on which flies were given access.

A scanning electron microscopic study was made of the everted and closed mouth parts of the stable fly. Given the lymphocyte count in blood from the cow used in the manual vector transmission experiment, it was calculated that 3,950 mouth part volumes would be necessary to transmit blv. This estimate and our negative transmission results indicated that the stable fly is not a blv vector of consequence.
Sequential study of visceral lesions caused by isolates of an avian osteopetrosis virus (myeloblastosis-associated virus)
Authors: Powers Barbara E. , Norrdin Robert W. , Snyder Stanley P. , Smith Ralph E.
Published: February 2025

Ten-day-old chicken embryos were inoculated with isolates of myeloblastosis-associated virus that induced osteopetrosis of slow or rapid onset. Bursa of Fabricius, thymus, spleen, bone marrow, kidney, liver, and lung were examined at 15, 17, and 19 days in ovo and at 7 and 25 days after hatching by histologic and immunoperoxidase techniques. Tissues from 19-day-old in ovo embryos also were examined by electron microscopy. The lymphoid organs of embryos inoculated with all isolates manifested changes suggesting inhibited development. Virus was most often associated with macrophages, heterophils, and non-lymphoid stromal cells in these organs. Viral particles and antigen were abundant in tissues from embryos inoculated with slow-onset isolates, but cell necrosis was infrequent. The kidney and bursa had especially abundant viral particles and antigen. Conversely, viral particles and antigen were minimal in tissues from embryos inoculated with the rapid-onset isolate, yet intravascular cellular thrombi, substantial cell necrosis, and increased heterophils and hemocytoblasts were found.
Cardiopulmonary effects of restraint in dorsal recumbency on awake cattle
Authors: Klein Lin , Fisher Nancy
Published: February 2025

The cardiopulmonary effects of dorsal recumbency were studied in awake cows restrained for surgical correction of left displaced abomasum. During the recumbent period, PaO2, PaCO2, arterial pH, and base excess values were significantly decreased. Heart rate, respiratory rate, blood hemoglobin concentrations, and rectal temperature increased significantly.
Comparison of staple and suture techniques for end-to-end anastomosis of the small colon in horses
Authors: Hanson R. Reid , Nixon Alan J. , Calderwood-Mays M. , Gronwall R. , Pendergast Jane F.
Published: February 2025

Two techniques for end-to-end anastomosis of the small colon were evaluated in each of 6 horses. A simple interrupted suture pattern that excluded the mucosa and was oversewn with an inverting suture was compared with a triangulated double-row pattern of stainless steel staples. Anastomotic sites were evaluated at 2 weeks, 2 months, and 6 months for extent of abdominal adhesions, lumen diameter at anastomotic sites, bursting pressures, and healing response. Clinical postoperative complications were not associated with either technique. At postmortem examination, there was extensive adhesion formation from the mesocolon to the stapled anastomotic site. The suture technique resulted in greater luminal diameters (P ≤ 0.05), with good apposition of the tissue layers. Staples were missing as early as 2 weeks after surgery, and their loss was associated with separation of the muscularis at later evaluation periods. Regardless of technique, all but one anastomotic segment burst away from the anastomotic site along the mesenteric taenial band. For the 12 anastomoses performed in normal horses, the suturing technique was better than the stapling technique because of significantly larger lumen diameters, better anastomotic healing, and minimal intra-abdominal adhesion formation.
In vitro effects of a mixture of Escherichia coli heat-stable enterotoxins on chloride flux in everted jejunal sacs of male pigs
Authors: Panichkriangkrai Wara , Ahrens Franklin A.
Published: February 2025

In vitro effects of a mixture of Escherichia coli heat-stable enterotoxins (sta and stb) on isolated jejunum of 3-week-old male pigs were studied, using everted intestinal sac techniques. Heat-stable enterotoxins increased chloride secretion and chloride absorption in everted intestinal sacs. The increase of secretory flux was greater than that for absorptive flux. Vasoactive intestinal peptide (6 × 10−9M) increased chloride secretion, but had no effect on chloride absorption. Neither vasoactive intestinal peptide nor pilocarpine (10−5M) had additive effect to st. Secretory effects of st were not blocked by atropine (2 × 10−5M), clonidine (10−6M), or morphine (4.2 × 10−6M).
Insulin and growth hormone responses to glucose infusion in mature and first-lactation dairy cows
Authors: McClary David G. , Sartin James L. , Kemppainen Robert J. , Williams John C.
Published: February 2025

Five mature Holstein cows and 6 first-lactation Holstein cows were administered 100 mg of glucose/kg of body weight, iv, over a 20-minute period on postpartum day 30. A series (preinfusion, glucose infusion, and post-infusion) of blood samples was collected at −15, −10, −5, 5, 10, 15, 20, 30, 45, 60, 75, 90, 105, and 120 minutes from the start of the infusion. Serum was obtained and was assayed for glucose, immunoreactive insulin (iri), growth hormone (gh), and free fatty acid concentrations. Baseline glucose and free fatty acid concentrations were similar in cattle of both groups throughout the sample collection period. Both groups of cattle disposed of the infused glucose in a similar manner. The first-lactation cows secreted significantly (P < 0.0001) more iri to utilize the glucose load than did the mature cows, 71 ± 13 μU/ml vs 38 ± 7 μU/ml, respectively (mean ± sem).

Preinfusion and glucose infusion gh concentrations were similar in cattle of both groups. In the postinfusion period, gh values were significantly (P < 0.0002) higher in the first-lactation cows (8.7 ±1.8 ng/ml) than in the mature cows (5.8 ± 1.6 ng/ml).

Compared with that in the mature cows, the higher iri concentration required by the first-lactation cows to utilize approximately the same glucose load suggested that first-lactation cows were insulin resistant. The increased insulin response to increased glucose concentration may be one reason first-lactation cows produce less milk than do mature cows. Other factors, such as variation in the ability of the mammary gland to synthesize milk cannot be excluded.
Disposition and excretion of flunixin meglumine in horses
Authors: Soma Lawrence R. , Behrend Ellen , Rudy Jeffrey , Sweeney Raymond W.
Published: February 2025

The disposition of flunixin meglumine administered iv at a dosage of 1.1 mg/kg was described by a 2-compartment model; the α and β half-lives (t1/2) were 0.61 and 1.5 hours, respectively. When administered iv at a rate of 2.2 mg/kg, the disposition was best described by a 3-compartment model, and the α, β, and λ t1/2 were 0.16, 1.52, and 6.00 hours, respectively. The zero-time plasma concentrations after flunixin meglumine was administered at 1.1 and 2.2 mg/kg were 9.3 ± 0.76 and 21.5 ± 7.4 mg/L, respectively. The bioavailability after oral administration of 1.1 mg/kg was 85.8%. The absorption t1/2 was 0.57 hours, with a peak concentration of 2.50 ± 1.25 mg/L. The cumulative urinary recoveries for iv and oral administrations were 61.0% and 63.3%, respectively, of the dose for the 12-hour collection period. The final asymptotic points of urine excretion after iv and oral administrations were 406.4 ± 65.5 and 357.7 ± 53.5 mg, respectively, which represented 75.5 and 77.5% of the drug accounted for between 30 and 35 hours after administration. Flunixin meglumine was rapidly excreted in urine over a 2- to 4-hour period after drug administration and was highly bound to protein in plasma.
Immune response to vaccinia virus and recombinant virus products in dogs
Authors: Appel M. J. G. , Paoletti E.
Published: February 2025

A study was undertaken to determine the safety and suitability of vaccinia virus as an eukaryotic expression vector in dogs. Clinical signs were not seen in inoculated dogs, with the exception of small nodules at the site of inoculation. Vaccinia virus did not spread from dogs that were inoculated by sc (n = 5), intradermal (id; n = 13), or intranasal (n = 3) routes to noninoculated dogs maintained in close contact. Replication of vaccinia virus appeared to be restricted in dogs because ≥ 105 plaque-forming units of virus were required to induce an immune response by id inoculation. Results were better with id inoculation than with sc or intranasal inoculations. Repeated inoculations enhanced serum antibody titers, and annual reinoculation resulted in boosting of antibody titers. Maternal antibody interfered with virus replication and antibody production. Recombinant virus products induced antibody formation in dogs to human influenza-A virus, herpes simplex virus, and human hepatitis-B virus antigens. It was concluded that vaccinia virus would be safe and suitable as an eukaryotic expression vector in dogs.
Neodymium:yttrium, aluminum, and garnet laser energy delivered transsclerally to the ciliary body of dogs
Authors: Nasisse Mark P. , Davidson Michael G. , MacLachlan N. James , Corbett Wayne , Tate Lloyd P. , Newman H. C. , Hardie Elizabeth M.
Published: February 2025

Using a hand-held optical fiber, a surgical neodym-ium:yttrium, aluminum, and garnet laser was used transsclerally on the left ciliary body of 25 dogs. Dogs were assigned to groups and were given low (100 J) and high (238 J) energy levels. In 12 dogs given 100-J energy, the intraocular pressure decreased a mean value of 6 mm of Hg below that in the untreated right eye. However, intraocular pressure returned to the pretreatment value 1 week after treatment. Intraocular lesions were not found by histologic examination 28 days later. In the second group of 13 dogs treated with 238-J energy, 6 were euthanatized 7 days after treatment and 7 were euthanatized 28 days after treatment. A mean decrease in intraocular pressure of 10 mm of Hg in the treated left eye, relative to the untreated right eye, persisted throughout the evaluation period. In eyes examined histologically 7 days after treatment, ciliary hemorrhage and necrosis were prominent. Other histologic changes were minimal and consisted principally of iris stromal hemorrhage. Of 7 dogs examined for 28 days after treatment, 6 remained sighted; in 1 dog, extensive intraocular hemorrhage occurred, eventually resulting in phthisis bulbi. Ciliary atrophy and fibrosis were the important histologic lesions observed 28 days after treatment. Laser energy delivered transsclerally by this optical system effectively induced ciliary necrosis and may be an effective treatment for canine glaucoma.
Evaluation of ivermectin for larvicidal effect in experimentally induced Parascaris equorum infections in pony foals
Authors: DiPietro J. A. , Lock T. F. , Todd K. S. , Sanecki R. K.
Published: February 2025

A controlled test was carried out on 15 pony foals inoculated with 1,500 ± 108.8 infective Parascaris equorum eggs. The foals were assigned to 3 treatment groups. Treatments given on postinoculation day 11 included 0.2 mg of ivermectin/kg of body weight, formulated as paste (n = 5), or liquid (n = 5), or no treatment (controls; n = 5). The foals were euthanatized on postinoculation day 25, and examined for larvae in the small intestine, lungs, and liver. Larvae were not found in foals treated with ivermectin liquid or paste, whereas significantly (P < 0.05) higher mean numbers (960.9; range, 379 to 1,736) of 4th-stage larvae were found in the controls. Histologic and gross examination of lungs and liver revealed pathologic changes attributable to P equorum migration that were similar in all foals. Adverse reactions to treatment were not observed.
Isolation of Chuzan virus, a new member of the Palyam subgroup of the genus Orbivirus, from cattle and Culicoides oxystoma in Japan
Authors: Miura Yasuo , Goto Yoshiyuki , Kubo Masanori , Kono Yuji
Published: February 2025

Five virus strains with identical antigenic properties were isolated from 3 rbc suspensions obtained from 2 healthy sentinel calves and from 2 pools of Culicoides oxystoma in cultures of a hamster lung cell line (HmLu-1). The virus was tentatively named Chuzan virus. The Chuzan virus was classified as a new member of the Palyam subgroup of the genus Orbivirus on the basis of its physicochemical, morphologic, and antigenic properties.
Serum resistance and virulence of Escherichia coli isolated from turkeys
Authors: Ellis Marlene G. , Arp Lawrence H. , Lamont Susan J.
Published: February 2025

Twenty-five strains of Escherichia coli isolated from turkeys were characterized for their serum resistance and virulence. An in vitro bactericidal assay was used to determine the serum resistance of E coli. Virulence was determined by survival time after iv inoculation of each strain into 3-week-old turkeys. Serum-resistant E coli strains were generally found to be virulent for turkeys, whereas serum-sensitive E coli strains were avirulent. Of the 25 strains, 18 strains were placed in the 2 categories of serum-resistant/virulent and serum-sensitive/avirulent. Five strains were serum-resistant and avirulent, and 2 strains were serum-sensitive and virulent. Serum resistance appears to be an important determinant of virulence for E coli in turkeys; however, the requirement for other virulence factors, in addition to serum resistance, was suggested by the finding that 5 serum-resistant strains were avirulent in turkeys.
Pharmacokinetics of gentamicin in laboratory rabbits
Authors: Curl James L. , Curl Joan S.
Published: February 2025

The pharmacokinetics of gentamicin was studied in 5 healthy adult laboratory rabbits of both sexes. Gentamicin sulfate (5% aqueous solution) was administered rapidly (iv) at a dosage of 3 mg/kg of body weight. Venous blood samples were taken at 0 (baseline), 5, 10, 15, and 30 minutes, and 1, 1.5, 2, 2.5, 3, 4, 5, and 6 hours after gentamicin administration. Serum gentamicin concentration was measured by radioimmunoassay. With the aid of a nonlinear least-squares program, the gentamicin concentration data were found to be best described by a 2-compartment model, with r2 = 0.989. Half-life, as determined from the terminal phase, was 56.6 ± 2.4 (mean ± sd) minutes. Calculation of total body clearance provided a mean of 1.69 ± 0.07 ml/min/kg of body weight. Volume of distribution, calculated from the area under the curve for each animal, was 0.138 ± 0.005 L/kg.
Morphologic and morphometric studies of the intrinsic laryngeal muscles in clinically normal adult dogs
Authors: Braund Kyle G. , Steiss Janet E. , Marshall Arvle E. , Mehta Jagjivan R. , Amling Karen A.
Published: February 2025

To establish normal histologic and histochemical data and to determine reference values for fiber type proportions (percentages, mean fiber diameters, atrophy and hypertrophy factors, and variability coefficients), a histochemical study was carried out on intrinsic muscles of the larynx (cricothyroid, cricoarytenoid lateralis, cricoarytenoid dorsalis, and thyroarytenoid muscles) of clinically normal dogs. Using myosin adenosine triphosphatase stain under acidic preincubation (pH 4.3) conditions, 3 histochemical fiber types—1, 2A, and 2C—were recognized. The percentage of type-2C fibers varied from 1 to 2% in thyroarytenoid muscles to approximately 10% in cricoarytenoid lateralis muscles. There was no significant difference in mean diameter between left- and right-side specimens of each muscle for type 1 vs type 2. The largest fibers (mean ± sd) of both types were observed in the cricothyroid muscles (type 1, 38.19 ± 7.76 μm; type 2, 43.25 ± 8.66 μm), and the smallest fibers were found in the thyroarytenoid muscles (type 1, 29.38 ± 5.12 μm; type 2, 33.84 ± 6.20 μm). Respective mean diameters of fiber types from cricoarytenoid dorsalis (type 1, 32.05 ± 5.69 μm; type 2, 38.95 ± 7.75 μm) and cricoarytenoid lateralis (type 1, 33.75 ± 5.98 μm; type 2, 37.09 ± 7.01 μm) muscles were similar. The histographic distribution of fiber type diameters was unimodal in all muscles. In each muscle, the mean fiber diameter of type-2 fibers was greater than that of type-1 fibers. Each muscle had a type-2 fiber predominance of variable degrees: cricothyroid and cricoarytenoid dorsalis muscles each had a mean type-1 to type-2 ratio of 40:60, whereas a pronounced type-2 fiber predominance was found in the cricoarytenoid lateralis (15:85) and thyroarytenoid (5:95) muscles. The number of fibers with internal nuclei never exceeded 1%, atrophy and hypertrophy factors typically were < 150, and variability coefficients were uniformly < 250. Muscle spindles were not observed in 40 intrinsic laryngeal muscle specimens.
Effect of phenytoin on the clinical signs and in vitro muscle twitch characteristics in horses with chronic intermittent rhabdomyolysis and myotonia
Authors: Beech J. , Fletcher J. E. , Lizzo F. , Johnston J.
Published: February 2025

In vitro twitch characteristics of the semimembranosus muscle were evaluated in 9 clinically normal horses, in 15 horses with chronic intermittent rhabdomyolysis (cir) and in 2 horses with myotonia. Effects of phenytoin on in vitro muscle twitch and clinical signs of cie and myotonia were evaluated in these same horses.

Times to 90% relaxation were prolonged in the horses with cir (mean ± sem, 186 ± 5.9 ms) and in 2 horses with myotonia (197 and 177 ms) compared with those in clinically normal horses (mean ± sem, 146 ±2.1 ms). Horses with cir also had significantly (P < 0.05) longer times to 50% relaxation, compared with clinically normal horses. In the group of horses with cir, Standardbreds had significantly (P < 0.05) longer times to 90% and 50% relaxation, compared with Thoroughbreds. Times to 100% peak tension did not differ among the groups. Administration of phenytoin directly into a muscle preparation bath solution had no effect on muscle twitch properties. After the initial muscle biopsy, phenytoin was administered orally for 7 to 10 days to 4 horses with cir, 2 myotonic horses, and 2 clinically normal horses before repeat biopsy from the same site in the contralateral semimembranosus muscle. Times to 90% relaxation decreased from 197 and 177 ms to 144 and 126 ms, respectively, in the 2 myotonic horses, from a mean of 192 (± 9) ms to 170 (± 9) ms in the 4 horses with cir and remained unchanged (154 and 140 ms before vs 155 and 139 ms after treatment) in the 2 clinically normal horses.

Phenytoin treatment of 8 horses with cir was associated with excellent clinical response in 7; 1 horse became lame, which prevented evaluation of the drug, and the other horse with normal muscle twitch properties continued to have seasonally severe cir. Of the 9 horses with cir that were not treated, 4 were lost to evaluation, 3 continued to be affected (but 1 of these often performed well), and 3 were reported to perform satisfactorily. After 10 days of treatment, the 2 myotonic horses had no change in gait or myotonic dimpling and myotonic discharges persisted, although subjectively, they were slightly decreased. Phenytoin appears to be useful clinically for treating horses with cir.