bluuebunny/crossref_metadata_2025 huggingface dataset:
Povidone-iodine lavage treatment of experimentally induced equine infectious arthritis
Authors: Bertone Alicia L. , McIlwraith C. Wayne , Jones Robert L. , Norrdin Robert W. , Radin M. Judith
Published: February 2025

Both tarsocrural joints of 4 horses were inoculated with 1.5 × 105 colony-forming units of Staphylococcus aureus. On days 1, 3, and 6, each horse had one tarsocrural joint lavaged with a balanced electrolyte solution and had the contralateral tarsocrural joint lavaged with 0.1% povidone-iodine solution. All horses were orally administered trimethoprim (5 mg/kg)/sufadiazine (25 mg/kg) combination twice daily and phenylbutazone (2 g) once daily for the duration of the study (21 days).

On days 0, 1, 3, 6, 9, 14, and 21, synovial fluid specimens were collected and analyzed for color, clarity, total protein concentration, wbc count and differential, and mucin clot-forming ability. Synovial fluid specimens collected on days 1, 3, 6, 9, 14, and 21 were bacteriologically cultured. On day 21, all horses were euthanatized, the tarsocrural joints were opened and examined, synovial membrane specimens were collected, bacteriologically cultured, and histologically evaluated, and articular cartilage specimens were histochemically evaluated. Repeated measures analysis of variance were used to evaluate differences between lavage solutions and among days for objective measurements. A paired t test was used to evaluate differences between solutions for the indices of synovial membrane inflammation and articular cartilage staining intensity with safranin-O-fast green. To be considered significant, the probability of a type-I error was < 0.05.

Significant differences were not found between joints lavaged with electrolyte solution vs povidone-iodine solution for synovial total protein concentration, wbc count, results of synovial fluid and membrane bacteriologie culture, synovial membrane inflammation, or articular cartilage glycosaminoglycan concentration. Generally, more synovial membrane surface fibrin was found in joints lavaged with balanced electrolyte solution than in joints lavaged with povidone-iodine solution. Therefore, use of 0.1% povidone-iodine did not have an advantage over use of balanced electrolyte solution as an irrigation solution in through-and-through joint lavage for the treatment of infecious arthritis in the horse.
Characterization and identification of Mycobacterium smegmatis in bovine mastitis
Authors: Schultze W. Donald , Brasso William B.
Published: February 2025

Twenty morphologically similar strains of a Mycobacterium sp isolated from milk of cows with bovine mastitis in the US Department of Agriculture dairy herd were identified as M smegmatis. Mastitis isolates submitted from Vermont and Washington also were identified as M smegmatis. A scheme for presumptive identification of rapidly growing mycobacteria was developed, using culture media and bactériologie techniques commonly used in mastitis diagnostic laboratories. Important tests used were acid-fast staining, rapidity of growth, pigmentation, nitrate reduction, arylsulfatase activity, mucic acid utilization, acid production from galactose, rhamnose, and inositol, and growth at 45 C and 52 C.
Relationship of fetal age at conjunctival exposure of pregnant heifers and Brucella abortus isolation
Authors: Crawford Richard P. , Adams L. Garry , Williams John D.
Published: February 2025

Pregnant heifers were exposed by a conjunctival inoculation with 1 − 107 colony-forming units of Brucella abortus strain 2308. At parturition, milk and uterine samples from dams plus samples from dead calves were cultured bacteriologically for Brucella. The logistic regression probability of B abortus isolation increased from 0.22 to 0.90, as fetal age at exposure of heifers increased from 60 to 150 gestation days. Strain 2308 was recovered at parturition from 14 (64%) of 22, 17 (71%) of 24, and all 28 (100%) heifers that were at gestation days < 127, 127 to 157, and > 157, respectively, at time of exposure. The number of infected heifers and the number of samples positive for B abortus were significantly increased as fetal age at exposure of heifers increased from gestation days < 127 to > 157 (Χ2 > 10, P < 0.005).
Role of Haemophilus pleuropneumoniae lipopolysaccharide endotoxin in the pathogenesis of porcine Haemophilus pleuropneumonia
Authors: Udeze Frank A. , Latimer Kenneth S. , Kadis Solomon
Published: February 2025

Intact Haemophilus pleuropneumoniae cells (strain Shope 1, serotype 1), highly purified lipopolysaccharide (lps) obtained from this strain of H pleuropneumoniae, as well as from Escherichia coli 0111:B4, filter-sterilized H pleuropneumoniae cell-free culture supernatant fluid, and heat-inactivated supernatant fluid were given intranasally to CF1 mice and intratracheally to pigs.

Pulmonary lesions induced by H pleuropneumoniae in mice were similar to those induced by H pleuropneumoniae in pigs. Histologically, lungs of mice and pigs killed 1 or 2 days after inoculation with 200 μg of highly purified H pleuropneumoniae lps had lesions similar to one another and were similar to those in mice and pigs given intact H pleuropneumoniae, except that little or no necrosis or hemorrhage was observed. In mice killed 1 or 2 days after inoculation of 200 μg of E coli 0111:B4 lps, pulmonary lesions were similar to those in mice given H pleuropneumoniae lps.

Pulmonary lesions in mice given cell-free culture supernatant fluid obtained from a midlog-phase growth culture of H pleuropneumoniae cultivated in a chemically defined medium were severe and consisted of neutrophil infiltration and extensive necrosis. In mice, the heat-inactivated supernatant fluid produced mild lesions that consisted of foci of neutrophil aggregation and no necrosis. Extensive necrosis observed in lesions caused by cell-free culture supernatant fluid could be attributed to the action of a heat-labile component, perhaps by the extracellular heat-labile hemolysin produced by H pleuropneumoniae cultivated in chemically defined medium. A lps endotoxin and a heat-labile factor may be involved in the pulmonary lesion development in the acute phase of porcine Haemophilus pleuropneumonia.
Association of enterotoxigenic Bacteroides fragilis with diarrheal disease in young pigs
Authors: Myers Lyle L. , Shoop Douglas S.
Published: February 2025

Enterotoxigenic Bacteroides fragilis (etbf) was isolated from intestinal contents of 10 of 45 pigs with diarrhea. Of 10 etbf-positive pigs, seven were 1 to 4 weeks of age, whereas three pigs had diarrhea after weaning (6 to 8 weeks of age). Of ten pigs infected with etbf, nine were also infected with K88-positive Escherichia coli, rotavirus, Coronavirus, coccidia, or Cryptosporidium. Of 11 conventional pigs exposed to etbf at 1 to 2 days of age, two subsequently developed fatal postweaning diarrhea. An etbf isolate, serologically similar to the challenge-exposure strain, was isolated from the feces of the two diarrheal pigs, but not from three healthy littermates.

Fatal enteric disease occurred in 11 of 12 adult rabbits with ligated ceca after approximately 5 − 109 colony-forming units of etbf were injected into the ileum. Disease in rabbits was characterized by anorexia and severe, mucoid, hemorrhagic diarrhea. Of 11 rabbits given non-etbf or sterile brain-heart infusion broth, ten remained clinically normal during the 7-day observation period.
Risk factors associated with mastitis in dairy goats
Authors: East N. E. , Birnie E. F. , Farver T. B.
Published: February 2025

Prevalence of intramammary infection in healthy goats was determined from 4,662 composite udder samples taken over a 9-month period. For each doe, a colostral sample and 2 milk samples were collected. Breed, age, number of days not lactating before kidding, number of lactation days, and kidding date were recorded. Coagulase-negative Staphylococcus spp were isolated from 17.5% of does, Staphylococcus aureus from 3.1%, Mycoplasma spp from 1.2%, Streptococcus spp from 0.3%, and gram-negative bacteria from 2.0%. Gram-negative organisms were associated with intermittent infections, whereas coagulase-negative staphylococci were associated with persistent infections. Intramammary infection was related to breed, number of days not lactating, and number of lactation days, as determined by log-linear analysis. Does of the Nubian breed, does with nonlactating periods of > 60 days, and does in the first and last third of a standard 305-day lactation appeared to be at higher risk for intramammary infection.
Chronic urinary tract infection in dogs: Induction by inoculation with bacteria via percutaneous nephropyelostomy
Authors: Ling Gerald V. , Lowenstine Linda J. , Gullen John M. , Ackerman Norman , Ruby Annette L.
Published: February 2025

Dogs were inoculated via percutaneous nephropyelostomy with bacteria isolated from canine patients with urinary tract infections (4 dogs were inoculated with Escherichia coli, 2 were inoculated with Proteus mirabilis, and 1 was inoculated with coagulase-positive staphylococci). At approximately monthly intervals after bacterial inoculation, bladder urine specimens were collected via antepubic cystocentesis, and renal pelvic urine specimens were collected via percutaneous nephropyelocentesis. Dogs were euthanatized between 89 and 294 days after bacterial inoculation. Extensive microscopic examination was conducted on the urinary tract of each dog.

The dogs did not develop any of the common clinical signs of urinary tract infections (ie, increased frequency of urination, fever, craniodorsal abdominal [renal] pain, or malaise). Inflammation in the lower urinary tract of the dogs was more severe than that in the kidneys. Although pyelitis was present, extension into the outer medulla and renal cortex seemed to be confined to nephropyelostomy tracts. The most severe bladder lesion was found in the dog that developed cystic calculi after inoculation with coagulase-positive staphylococci.
Parvovirus-induced regression of canine transmissible venereal sarcoma
Authors: Yang T. J.
Published: February 2025

In 1981, during the worldwide canine parvovirus (pv) epizootic, canine transmissible venereal sarcomas growing in Beagles in a colony regressed earlier than expected after the dogs became infected with pv. Subsequent studies revealed that modified-live pv vaccine (feline panleu-kopenia virus) was capable of preventing tumor transplantation when the vaccine was inoculated simultaneously with the tumor in a site distant from the implantation site. However, the pv vaccine had no effect if it was inoculated 3 or 18 days after the tumor was transplanted.
Pharmacokinetics and serum concentrations of cephapirin in neonatal foals
Authors: Brown Murray P. , Gronwall Ronald , Gossman Tim B. , Houston A. E.
Published: February 2025

Six healthy foals, from 4 to 6 days of age, were given a single im injection of sodium cephapirin (250 mg/ml) at a rate of 20 mg/kg of body weight. Serum concentrations of cephapirin were measured serially over an 8-hour period. The mean peak serum concentration was 21.2 µg/ ml at 10 minutes. The overall elimination rate constant was 1.06/hr and the elimination half-life was 0.70 hour. The apparent volume of distribution at steady state was 1.06 L/kg and plasma clearance was 1,105 ml/hr/kg.
Disposition of fenbendazole in the goat
Authors: Short Charles R. , Barker Steven A. , Hsieh Lily C. , Ou Su-Pin , Davis Lloyd E. , Koritz Gary , Neff-Davis Carol A. , Bevill Richard F. , Munsiff Irene J. , Sharma Gopal C.
Published: February 2025

The disposition of fenbendazole was studied in goats after oral or iv administration. Plasma concentration vs time profiles were determined for fenbendazole and all of its metabolites. The total excretion of the drug and its metabolites in urine and feces was also measured for 6 days. A biliary cannula was inserted in 1 goat to study the excretion of fenbendazole and its metabolites into the bile. Fenbendazole was converted to its sulfoxide (oxfendazole), and the sulfone, primary amine, and p-hydroxylated metabolites. The active metabolite, oxfendazole, appeared in plasma, but only trace amounts were found in feces or urine. The major excretory metabolite was p-hydroxyfenbendazole.
Effect of dietary protein on porcine colonic microstructure and function
Authors: Dobesh Gerald D. , Clemens Edgar T.
Published: February 2025

Twelve feeder pigs were used to determine the effects of dietary protein on colonic microstructure and function. Scanning electron microscopy indicated marked differences in mucosal structure of pigs fed 12% vs 20% crude protein. Quantitative assessment of the morphologic features of the colon, using light microscopy, indicated significant differences in the mucosa of pigs fed 12% vs 20% crude protein and significant differences between the proximal and distal portions of the colon. Morphologic changes were associated with differences in the colonic transport of fluids and electrolytes. Dietary protein principally affected the transport of sodium, bicarbonate, and acetate. The transport of total volatile fatty acids and acetate flux were significantly different between the proximal and distal portions of the colon.
Clinical pathologic alterations in horses during a water deprivation test
Authors: Genetzky R. M. , Loparco F. V. , Ledet A. E.
Published: February 2025

A 72-hour water deprivation test was performed in 12 horses to determine clinical pathologic changes. Reference values for electrolyte (X) clearance, expressed as a percentage of creatinine clearance (clCR; %clCRX), were also determined. A comparison was made between urine concentration measurement techniques.

Results of %clCRX determination in 12 horses before water deprivation were 0.034 ± 0.095 %clCRNa, 42.4 ± 9.8 %clCRK, 0.352 ± 0.190 %clCRCl, and 0.710 ± 0.250 %clCRP. During water deprivation, there was individual variation for electrolyte clearances, but Na excretion increased significantly (P < 0.01) at 24 and 48 hours. After 48 hours’ water deprivation, %clCRNa decreased significantly, but was still greater than the initial clearance.

Plasma protein was a better indicator of water deprivation (dehydration) in the horse than was pcv. Electrolyte concentrations in serum and urine were determined. Little significant (P < 0.01) change in acid-base values was noticed after 72 hours’ water deprivation. Urine osmolality (as determined by osmometry) was compared with sp gr (determined by refractometry) in determining urine concentration. Initially, sp gr correlated well with urine osmolality determinations, but this correlation decreased after 48 hours.
Detection of bovine herpesvirus-1 nucleic acid sequences, using a dot-blot hybridization procedure
Authors: Andino R. H. , Torres H. N. , Polacino P. S. , Schudel A. , Palma E. L.
Published: February 2025

A sensitive and specific procedure for the detection of Argentine isolates of bovine herpesvirus-1 was developed. The procedure was based on a dot-blot, nucleic acid hybridization, using 32P, nick-translated, plasmidic probes. The probes contained cloned Bam H1 restriction fragments in the left half of the viral genome. The detection limit of the procedure was 10 pg of viral dna.
Humoral immune response of calves to bluetongue virus infection
Authors: MacLachlan N. James , Heidner Hans W. , Fuller Frederick J.
Published: February 2025

Humoral immune responses of 7 calves to bluetongue virus (btv) infection were evaluated by plaque-reduction assay and immunoblotting. Most readily interpretable results were obtained with the immunoblot assay when colostrum-deprived calves were used, and sera were reacted with proteins in partially purified extracts of btv.

Viremia persisted in calves for 35 to 56 days, and btv coexisted in blood for several weeks with virus-specific neutralizing antibody. Calves developed antibody to virus protein 2, the major determinant of virus neutralization, at 14 to 28 days after inoculation; this time interval also coincided with the appearance of neutralizing antibody in serum. Virus clearance in btv-infected calves did not coincide with humoral immune responses to protein 2 or other virion proteins.
Isolation of Cache Valley virus and detection of antibody for selected arboviruses in Michigan horses in 1980
Authors: McLean Robert G. , Calisher Charles H. , Parham Gregory L.
Published: February 2025

Blood samples collected in September and November 1980 from 87 horses in southwestern Michigan were examined for virus isolation and for plaque-reduction neutralizing antibody against selected arboviruses. Cache Valley virus was isolated from the blood of a clinically normal horse in St Joseph County in September. The age-specific antibody prevalence for Cache Valley virus indicated enzootic transmission in the study area. The high antibody prevalence and the lack of age-specific antibody prevalence indicated sporadic, but intense, exposure to Jamestown Canyon virus. Low prevalences of antibody were detected for Highlands J, snowshoe hare, St Louis encephalitis, and trivittatus viruses.
Conjunctival and intramuscular vaccination of pigs with a live avirulent strain of Salmonella cholerae-suis
Authors: Kramer Theodore T. , Pardon P. , Marly J. , Bernard Serge
Published: February 2025

An avirulent mutant strain of Salmonella cholerae-suis was cloned for resistance to streptomycin and nalidixic acid. The mutant strain 33-13 also was used because of its avirulence and immunogenicity in mice. Weaned pigs were vaccinated with live strain 33-13; 5 pigs were vaccinated by conjunctivally administered 5.5 − 107 organisms (low dose), 5 were conjunctivally administered 5.5 − 109 organisms (high dose), and 5 pigs were administered 5.5 − 109 organisms (high dose) im. Transient fever and transient fecal shedding of the vaccine strain developed in pigs vaccinated im, but not in 2 groups of pigs vaccinated conjunctivally. After intratracheal administration of virulent strain 38-9, nonvaccinated control pigs (n = 9) developed persistent high fever, anorexia, bacteremia, diarrhea, and fecal shedding of strain 38-9, whereas vaccinated pigs remained afebrile and clinically normal. Nonvaccinated and uninfected sentinel pigs (n = 8) were kept in units of 2 pigs with each group of experimental pigs, and remained healthy throughout the experiment. Thirteen vaccinated and 7 nonvaccinated control pigs were killed 42 days after vaccination, and 2 vaccinated, 2 nonvaccinated, and 8 sentinel control pigs were killed 58 days after vaccination. Ten organs were evaluated by quantitative bacteriology on necropsy of all pigs for the presence of vaccine strain 33-13, and for virulent strain 38-9. Strain 33-13 was not found. Lung and liver, lesions were found in most of the nonvaccinated control pigs, with a high frequency of recovery of large numbers of strain 38-9 from the mesenteric lymph nodes, lungs, liver, and ileum. Strain 38-9 was rarely isolated from the 10 organs evaluated in the 3 groups of vaccinated pigs. Sentinel pigs in contact with vaccinated and control pigs were uninfected when killed on day 58.
Immunochemical characterization of proteins from scrapie-infected hamster brain, using immunoblot analysis
Authors: Wade W. F. , Dees C. , German T. L. , Marsh R. F.
Published: February 2025

Preparations of brain plasma membrane from scrapie-infected or noninfected hamsters were extracted with a î solvent and were used to inoculate rabbits. Antisera evaluated by immunoblot analysis revealed a protein of 45 kD in scrapie-infected hamster brain that had a greater signal compared with proteins of comparable relative mass in noninfected brain. This 45-kD protein was not increased in scrapie-infected mouse, sheep, or goat brain. Seemingly, the 45-kD protein may be a degradation product of glial fibrillary acidic protein.
Enzyme-linked immunosorbent assay for detection of antibodies to Rift Valley fever virus in ovine and bovine sera
Authors: Meegan J. M. , Yedloutschnig R. J. , Peleg B. A. , Shy Jaffa , Peters C. J. , Walker J. S. , Shope R. E.
Published: February 2025

An enzyme-linked immunosorbent assay (elisa) was developed for the rapid detection of antibodies to Rift Valley fever virus (rvfv) in ovine and bovine sera. Conditions to reduce nonspecific reactions were optimized. The elisa results correlated with those of a plaque-reduction neutralization test, revealing 100% specificity and 90.7% sensitivity. In sera from sheep and cattle inoculated against rvfv, the hemagglutination-inhibition test in combination with the elisa provided a better indication of response to killed rvfv vaccine than did either test alone.
In vitro platelet release by rat megakaryocytes: Effect of metabolic inhibitors and cytoskeletal disrupting agents
Authors: Handagama P. J. , Feldman B. F. , Jain N. C. , Farver T. B. , Kono C. S.
Published: February 2025

Development of an in vitro visual assay facilitated the study of large numbers of megakaryocytes undergoing proplatelet formation in short-term cultures. Approximately 9% of megakaryocytes formed platelets during a 24-hour period. In the presence of an inhibitor of anaerobic glycolysis (NaF), proplatelet formation was inhibited, whereas inhibitors of respiration (NaCN) did not significantly (P > 0.05) decrease proplatelet formation. Presence of the microtubule-disrupting agents colchicine and vincristine sulfate in culture medium inhibited proplatelet formation, whereas the microfilament-disrupting agent cytochalasin B had a less pronounced inhibition.
N-Acetyl-β-D-glucosaminidase activities, milk somatic cell counts, and blood leukocyte and erythrocyte counts in cows after heat-induced stress or after intravenous administration of adrenocorticotropic hormone
Authors: Berning L. M. , Paape M. J. , Miller R. H. , LeDane R. A.
Published: February 2025

Six midlactation, nonpregnant cows were subjected to heat-induced stress or to repeated injections of adrenocorticotropic hormone (acth). The heat stress (experiment 1) consisted of subjecting the cows to 7 days of fluctuating temperatures (21 C during the day, 32 C during the night). The acth-induced stress (experiment 2) was accomplished by giving each of the cows 100 IU of acth twice daily for 4 consecutive days. The cows' milk somatic cell counts (mscc), milk N-acetyl-β-d-glucosaminidase (NAGase) activity, quarter milk production (ie, milk production per mammary quarter), blood leukocyte counts, and plasma concentrations of NAGase were monitored in both experiments. Although heat stress did not result in significant differences in NAGase, heat stress did significantly (P < 0.05) decrease milk production.

The acth administrations resulted in increased milk NAGase activity, mscc, and blood leukocyte counts, and in decreased plasma NAGase activity and quarter milk production. Therefore, milk NAGase activity and Msec were not affected by short-term heat stress, but were increased by acth-induced stress. Blood erythrocyte concentrations were not affected by heat stress or by acth-induced stress.
Immunologic memory responses induced in BALB/c mice by cross-linked outer membrane extracts of four Salmonella serotypes
Authors: Kudrna David A. , Teresa George W. , Arnzen Jeanene M. , Beard K. Scott , Olson Deborah
Published: February 2025

Outer membrane proteins (omp), extracted from Salmonella enteritidis, S anatum, S typhimurium, and S infantis, were cross-linked to form a large immunogen (4-omp-lipopolysaccharide [lps]). Vaccinations with 4-omp-lps dissolved in phosphate-buffered saline solution and 4-omp-lps emulsified with muramyl dipeptide were capable of eliciting specific and sustained primary IgM and IgG responses in BALB/c mice, as well as inducing immunologic memory for 130 days. In addition to 4-omp-lps-specific responses, substantial IgM and IgG responses specific for each live homologous organism were detected over the 130-day trial. In comparison with vaccination with 4-omp-lps dissolved in phosphate-buffered saline solution, responses specific for the antigen or the homologous Salmonella were not markedly increased in mice vaccinated with 4-omp-lps emulsified with muramyl dipeptide. Seemingly, cross-linked omp, without the inclusion of muramyl dipeptide, may have potential as vaccine components and may induce immunologic memory.
Compound-action potentials of myelinated fibers in the saphenous nerve of the dog: In situ electrophysiologic and behavioral studies
Authors: Whalen L. R. , Spurgeon T. L. , Boggie L. C.
Published: February 2025

Compound-action potentials (cap) were recorded directly from the surface of fascicles of the distal portion of the saphenous nerve (sn) of dogs in situ. Potentials were evoked through needle electrodes and were recorded through bipolar stainless steel electrodes.

Stimuli of 10-μs duration and of 0.4 ± 0.15-mA amplitude evoked a monophasic cap. Sensory conduction velocities of afferent fibers, the action potentials of which contributed to this evoked compound potential, ranged from 62.4 ± 2.8 m/s for the most rapidly conducting fibers to 30.5 ± 2.4 m/s for the least rapidly conducting fibers. Stimuli of 25-μs duration and of 2.2 ± 0.8-mA amplitude evoked a second, longer latency cap in addition to the first cap. Sensory conduction velocities of afferent fibers, the action potentials of which contributed to this evoked compound potential, ranged from 20.4 ± 2.9 m/s for the most rapidly conducting fibers to 13.7 ± 1.0 m/s for the least rapidly conducting fibers. Low-amplitude, negative peaks were recorded between the first and second major potentials elicited by the longer duration stimuli. Stimuli of still longer duration and higher currents induced contractions of the caudal part of the sartorius muscle by current spread in 9 of 12 dogs. In 3 dogs, a third monophasic cap was evoked, having a maximal conduction velocity of 1.7 ± 0.2 m/s.

After section of the distal portion of the sn on one side in each of 2 dogs, an absence of signs of sensory deficit was found on clinical neurologic examination. The area of cutaneous innervation of the cranial branch of the distal portion of the sn was determined electrophysiologically.
Seasonal occurrence and distribution of Gasterophilus intestinalis and Gasterophilus nasalis in the stomachs of equids in Texas
Authors: Price R. E. , Stromberg P. C.
Published: February 2025

Stomachs of 271 horses and ponies from 2 sources were evaluated for the presence of Gasterophilus intestinalis and G nasalis larvae, through 2 overlapping 12-month periods of bot fly activity in southern Texas. Equids (n = 140) from one source had nearly 96% of their stomachs infected, whereas equids (n = 131) from another source had 44% of their stomachs infected by Gasterophilus spp.

Seasonal dynamics of the bot infection indicated the highest average number of bot larvae per infected stomach occurred in the winter and spring. The smallest average number of bots per infected stomach occurred in the fall. Higher percentages of early (2nd instar plus young 3rd instar) larvae of G intestinalis were observed in the fall in equids from both sources. The late (more fully developed older 3rd instar) G intestinalis larvae outnumbered the early larvae in the winter, spring, and summer. Seasonal variation in numbers and development status of the larvae was consistent with the largest period of adult bot fly activity occurring during the fall.

The 2 species of bots had different predilection sites of attachment. Gasterophilus intestinalis larvae concentrated in the nonglandular portions of the stomach near the margo plicatus on the cranial (parietal) surface of the stomach and in the most dorsal extent of the saccus cecus. Gasterophilus nasalis larvae attached almost exclusively in the first ampulla of the duodenum. Predilection sites for both Gasterophilus spp occurred in dorsally positioned areas in the alimentary tract favoring increased availability of oxygen.
Pharmacokinetics and interactions of digoxin with phenobarbital in dogs
Authors: Ravis W. R. , Pedersoli W. M. , Turco J. D.
Published: February 2025

In one experiment, 5 dogs were administered digoxin (0.022 mg/kg of body weight, iv), were rested for 2 weeks, were then given phenobarbital (13.2 mg/kg orally) for 14 days, and then were given digoxin again (0.022 mg/kg, iv). Comparing prephenobarbital (control) digoxin half-lives of 42.4 ± 8.8 hours and postphenobarbital digoxin half-lives of 18.0 ± 2.2 hours, the half-life was significantly (P < 0.05) decreased after phenobarbital administration. Clearance was increased by 84%, and the volume of distribution given was decreased by 34%.

In a second experiment, 5 dogs were given digoxin (0.022 mg/kg, orally) daily for 11 days, and the digoxin kinetics were evaluated after the last dosing. The dogs were then rested and given phenobarbital (13.2 mg/kg, orally) once daily for 14 days and digoxin (0.022 mg/kg) once daily for 11 days, and the pharmacokinetics of digoxin was determined on the last day of dosing. Significant differences in steady-state serum concentrations and the pharmacokinetics of digoxin were not found between the control and phenobarbital phases of the experiment. Mean (± SD) half-lives of digoxin were 29.0 ± 7.2 hours before phenobarbital treatment (control) and were 34.8 ± 7.2 hours after phenobarbital treatment.

In comparing results of the single-dose experiment vs the oral multiple-dose experiment, dogs had shorter half-lives for digoxin after multiple dosing. Therefore, if phenobarbital and digoxin are to be chronically coadministered orally, an adjustment in the digoxin dose is not necessary.
Pharmacokinetics of phenolsulfonphthalein in horse and pony mares
Authors: Hinchcliff Kenneth W. , McGuirk Sheila M. , MacWilliams Peter S.
Published: February 2025

Pharmacokinetics of phenolsulfonphthalein (psp) in horse and pony mares was determined after injection of 1 mg/kg of body weight, iv. A plasma psp concentration vs time curve was described adequately in horses and ponies by an open, 2-compartment model. There were significant differences in the elimination phase parameters, apparent volume of distribution at steady state, and apparent volume of distribution of horses and ponies. The harmonic mean elimination half-life of psp in horses was significantly longer (P < 0.001) than that in the ponies (16.4 and 10.0 minutes, respectively). The mean plasma clearance of psp in horses was significantly (P < 0.05) less than that in ponies (0.00554 and 0.00701 L/min/kg, respectively). There was no difference between horses and ponies in the metabolic clearance of psp. The fraction of the administered dose of psp excreted in the urine in the first 15 minutes was not significantly different between horses and ponies.
Pharmacokinetics of oxytetracycline hydrochloride in rabbits
Authors: McElroy Donita E. , Ravis William R. , Clark Carl H.
Published: February 2025

Pharmacokinetics of oxytetracycline HCl (otc) was studied in rabbits. After 10 mg of otc/kg of body weight was administered iv, the distribution half-life was 0.06 hour, terminal half-life was 1.32 hours, volume of distribution area was 0.861 L/kg, and total body clearance was 0.434 L/kg/h. After 10 mg of otc/kg was given im, the absorption half-life was 2.09 hours, extent of absorption was 71.4%, and total body clearance of the absorbed fraction was 0.576 L/kg/h. Based on these kinetic data, a dosage of 15 mg of otc/kg, every 8 hours was developed. This dose given im for 7 consecutive days resulted in observed steady-state maximum and minimum concentrations (mean ± sd) of 4.7 ± 0.3 μg/ml and 3.2 ± 0.6 μg/ml, respectively. Twice this dose (30 mg of otc/kg, every 8 hours) given im caused anorexia and diarrhea.
Canine distemper virus-induced thrombocytopenia
Authors: Axthelm Michael K. , Krakowka Steven
Published: February 2025

Effects of canine distemper virus (cdv) infection on circulating platelet values were studied in gnotobiotic dogs inoculated with R252-cdv. Thrombocytopenia (< 200,000 platelets/μl) was present on postinoculation day (pid) 5 and persisted through pid 15. Peak thrombocytopenia occurred on pid 10 (< 85,000 platelets/μl). Thrombocytopenia was accompanied by lymphopenia, neutropenia, and monocytopenia. Platelet membrane-bound cdv antigen and IgG were present from pid 7 onward; neither the third component of complement nor IgM was detected on platelets from cdv-inoculated dogs. The mean number of megakaryocytes per unit of bone marrow surface area was unchanged. Megakaryocyte infection was present in dogs euthanatized on pid 4 (0.33%), increased slightly in dogs euthanatized on pid 8 (3%), and increased sharply in dogs euthanatized on pid 9 and 10 to 17.8% and 8.3%, respectively. Phagocytosis of platelets by stellate reticuloendothelial (Kupffer's) cells in the liver was prominent in dogs euthanatized from pid 5 onward. Seemingly, cdv-induced thrombocytopenia was mediated by virus-antibody immune complexes on platelet membranes. Decreased platelet production after pid 8 resulting from direct viral infection of megakaryocytes was a likely contributing factor and occurred against a background of profound virus-induced dysfunctions of all hematopoietic cellular elements.
Effect of RA233 on metastasis in dogs with osteosarcomas
Authors: Hamilton Helen B. , LaRue Susan M. , Withrow Stephen J.
Published: February 2025

The influence of RA233, an inhibitor of platelet function, on the occurrence of metastasis in 18 dogs with osteosarcomas was evaluated. At feast 24 hours before surgical removal of the primary tumor, dogs were given RA233 orally (20 mg/kg of body weight divided into 3 equal doses).

Original sites of the osteosarcoma included humerus, 6 dogs; radius, 5 dogs; tibia, 3 dogs; femur, 2 dogs; maxilla, 1 dog; and mandible, 1 dog. Survival time for 13 dogs euthanatized for progression of neoplastic disease ranged from 3 months to 10 months, with a mean survival time of 5.5 months. Medication was discontinued in 1 dog because of possible adverse reaction. One dog died of disease unrelated to the tumor, and one dog was euthanatized after the surgery. Two dogs were tumor free 9 and 17 months after surgery. Seemingly, the metastasis potential was not diminished in dogs given 20 mg of RA233/kg/day.
Comparisons of feline panleukopenia virus, canine parvovirus, raccoon parvovirus, and mink enteritis virus and their pathogenicity for mink and ferrets
Authors: Parrish Colin R. , Leathers Charles W. , Pearson Renee , Gorham John R.
Published: February 2025

Parvoviruses from mink (mink enteritis virus [mev]), cats (feline panleukopenia virus [fpv]), raccoons (raccoon parvovirus [rpv]), and dogs (canine parvovirus [cpv]) were compared. Restriction enzyme analysis of the viral rep-licative-form dna revealed no consistent differences between fpv and rpv isolates, but cpv and mev isolates could be distinguished readily from other virus types.

Feline panleukopenia virus, rpv, and mev, but not cpv, replicated to high titers in mink. However, on the first passage, disease and microscopic lesions were observed only in mink inoculated with mev. Feline panleukopenia virus and rpv isolates replicated in ferrets, but disease or microscopic lesions were not observed. Feline panleukopenia virus and rpv isolates could be passaged repeatedly in mink and ferrets. Virulence of fpv and rpv isolates was low compared with that of mev, and only a single mink inoculated with fpv or with rpv developed clinical disease on the sixth passage of virus.
Antibodies to spotted fever-group rickettsiae in dogs in North Carolina
Authors: Breitschwerdt Edward B. , Moncol Daniel J. , Corbett Wayne T. , MacCormack J. Newton , Burgdorfer Willy , Ford Richard B. , Levy Michael G.
Published: February 2025

A seroepidemiologic survey was conducted to determine the prevalence of antibodies reactive with 4 spotted fever-group (sfg) rickettsiae in sera of dogs from various geographic regions in North Carolina. Serum specimens were obtained from 600 dogs, and antibody titers were determined, using microimmunofluorescence. Data analysis (setting as the criterion for a positive result, a Rickettsia rickettsii titer ≥ 1:64) overestimated the actual prevalence of canine exposure to this rickettsia. When data were analyzed by considering each dog's serologic response to all 4 rickettsial antigens simultaneously, the prevalence rate for exposure to R montana was 15%, to R rhipicephali was 11%, and to R rickettsii was 5%. A definitive exposure to R bellii was not observed, and the identification of the specific inciting rickettsia could not be established for 13% of the dogs, because of identical highest titers to 2 or more antigens.

Our data indicate that canine exposure to R rhipicephali is prevalent in the eastern coastal region, whereas exposure to R montana takes place uniformly throughout the state. Rickettsia rickettsii exposure appears to be more prevalent in the central Piedmont region, but rarely is encountered in the western mountains. Regional sero-prevalence for canine R rickettsii exposure approximates that for human exposure. Our findings support earlier suggestions that dogs may serve as environmental sentinels for establishing the geographic prevalence of foci of spotted fever.
Serologie responses of calves to sequential infections with epizootic hemorrhagic disease virus serotypes
Authors: Bowen R. A.
Published: February 2025

Six calves were inoculated with 1 of 2 North American serotypes of epizootic hemorrhagic disease virus (ehdv) and then inoculated with the second serotype 16 weeks later. One calf did not develop an immune response to ehdv after primary inoculation and was removed from the study. Viremia after primary inoculation was transient. Although each infected calf developed a high serum neutralizing antibody titer to ehdv, at no time after inoculation with one or both viruses was antibody detected that neutralized any US serotypes of bluetongue virus. After exposure to both serotypes of ehdv, 4 of 5 calves developed antibodies that cross-reacted with group-specific bluetongue virus antigens.
In vitro sensitization and stimulation of bovine lymphocytes with encapsulated or nonencapsulated Smith strain of Staphylococcus aureus
Authors: Ojo-Amaize Emmanuel A. , Guidry Albert J.
Published: February 2025

An in vitro immunization procedure was developed, whereby bovine blood and mammary gland lymphocytes were isolated, and their blastogenic responses (measured by [3H]thymidine uptake) to sensitization and subsequent stimulation with selected antigens were determined. Capsular extracts of Staphylococcus aureus, encapsulated S aureus, and nonencapsulated S aureus were used as test antigens. Differences were observed between kinetics of the secondary response to encapsulated and nonencapsulated S aureus. The secondary response to nonencapsulated S aureus peaked in 48 hours, whereas the secondary response to the encapsulated S aureus peaked in 72 hours. The delayed peak response to encapsulated S aureus was observed only when encapsulated S aureus was used for sensitization of lymphocytes, regardless of whether the encapsulated or nonencapsulated strain was used for stimulation. Sensitization of lymphocytes with the nonencapsulated strain and stimulation with the encapsulated strain did not alter the kinetics of the secondary response of cells sensitized with the nonencapsulated strain. Seemingly, T and B cells were responsive to in vitro immunization with S aureus antigens.
Mechanism and isotypes involved in passive immunoglobulin transfer to the newborn alpaca (Lama pacos)
Authors: Garmendia Antonio E. , McGuire Travis C.
Published: February 2025

Crias, newborn alpacas (Lama pacos), that were almost agammaglobulinemic at birth had a 70% increase in total serum proteins within 24 hours largely because of absorption of γ globulins from colostrum. Immunoglobulin G was the isotype in highest concentration in colostrum and in serum from 24-hour-old crias. The serum IgG concentration of 10 crias increased linearly (r = 0.97) from a mean of 0.3 mg/ml ( ± 0.1 sd) for serum collected before crias suckled to a maximal mean of 30.1 mg/ml (± 8.1 sd) at 24 hours. The 24-hour concentration decreased by half in 10 days. Immunoglobulin M also was absorbed from colostrum and increased linearly (r = 0.99) from a mean of 0.5 mg/ml (± 0.1 sd) for serum collected before crias suckled to a maximal mean of 4.2 mg/ml (± 2.2 sd) 24 hours after birth. The 24-hour serum concentration of IgM decreased by half in 7 days. Therefore, on a weight basis, 7 times more IgG than IgM was transferred to crias; IgG accounted for > 85% of the passively transferred proteins in serum of 24-hour-old crias.

Absorption of functional antibodies of IgG and IgM isotypes from colostrum of immunized dams by crias also was demonstrated. Immunoglobulin G and IgM antibody titers to chicken RBC increased linearly to maximal geometric mean titers of 1,139 and 843, respectively, 24 hours after birth. The 24-hour IgG and IgM antibody titers decreased by half in 6 and 3.8 days, respectively.

Purified alpaca IgG had a molecular mass of 166 kilodaltons, a predominant γ mobility, and an extinction coefficient of 14.1. Purified alpaca IgM had a molecular mass of 1,000 kilodaltons, a β mobility, and an extinction coefficient of 12.8. In immunodiffusion, alpaca IgG had partial antigenic identity with human IgG, and alpaca IgM had partial antigenic identity with bovine IgM.
Neurophysiology maps of cutaneous innervation of the hind limb of sheep
Authors: Kirk E. J. , Kitchell R. L. , Johnson R. D.
Published: February 2025

The area of skin supplied by afferent fibers in a peripheral nerve is called the cutaneous area (ca) of that nerve. The ca of hind limb nerves that were responsive to movement of wool/hairs were mapped neurophysiol-ogically in 25 barbiturate-anesthetized sheep.

The ca of the dorsal cutaneous branches of the caudal lumbar spinal nerves and of the sacral spinal nerves extended over the lateral aspect of the thigh. The ca of the lateral cutaneous femoral nerve was restricted to the stifle region, that of the saphenous nerve did not reach the digits, that of the deep peroneal nerve lay between the 3rd and 4th digits, and that of the lateral plantar nerve was confined to the lateral aspect of the 4th digit. The ca of the superficial peroneal nerve enveloped the dorsal, medial, and lateral aspects of the distal portions of the hind limb. In some sheep, the boundaries of the ca of the superficial peroneal nerve were juxtaposed caudally in such way that the medial plantar nerve did not have an autonomous zone.

Differences in sizes of the ca resulted in corresponding differences in the overlap between adjacent ca and concomitant differences in the sizes of autonomous zones.
Effect of ranitidine on gastric acid secretion in young male horses
Authors: Campbell-Thompson Martha L. , Merritt A. M.
Published: February 2025

Gastric cannulas were placed surgically in 5 young male horses. After a 2-week recovery period, horses were studied once a week. Horses were fasted for 24 hours, and gastric fluid output was collected for 5 continuous hours. Volumes were recorded every 15 minutes, and pH and hydrogen ion concentration were determined in an aliquot from each period. In 10 basal experiments, using 5 horses, volume, pH, and hydrogen ion concentration were continuously variable. Mean acid output was 45.1 ± 2.02 μEq/15 min/kg (mean ± sem). In 6 experiments, using 3 horses, 0.5 mg of ranitidine/kg of body weight, given as an rv bolus after a 1-hour basal collection, significantly (P < 0.02) inhibited hourly total acid output for 4 hours, but did not significantly change pH. The cannulation technique was done without complications, and horses tolerated the cannula for several months. Seemingly, the horse has a continuously variable gastric acid secretion, and histamine type-2 receptors have a role in this process.
Adaptation of a colorimetric microtitration assay for quantifying Pasteurella haemolytica A1 leukotoxin and antileukotoxin
Authors: Vega Maria V. , Maheswaran Samuel K. , Leininger Joel R. , Ames Trevor R.
Published: February 2025

A colorimetric microtitration assay was adapted to quantify the cytotoxicity of Pasteurella haemolytica A1 leukotoxin to bovine neutrophils used as target cells. The viability of leukotoxin-treated target cells was detected by use of a tetrazolium dye that living cells reduced to dark blue formazan. The amount of formazan formed (which was quantified by use of an elisa plate reader) was directly proportional to the number of viable target cells. This assay system also was used to measure leu-kotoxin-neutralization antibody titers of bovine serum and lung lavage specimens obtained during vaccination experiments. The major advantages of this assay over other methods such as the 51Cr-release and trypan blue-exclusion assays are precision, rapidity, and low cost; it also does not use radioisotopes.
Experimental infection of weanling pigs with Salmonella typhisuis: Effect of feeding low concentrations of chlortetracycline, penicillin, and sulfamethazine
Authors: Fenwick Brad W. , Olander Harvey J.
Published: February 2025

Clinical and pathologic variables of Salmonella typhisuis infections were studied in weanling pigs. The influence of daily feeding of low concentrations of Chlortetracycline, penicillin, and sulfamethazine on S typhisuis infection also was determined.

Ten pigs (group 1) given feed containing low concentrations of Chlortetracycline, penicillin, and sulfamethazine when orally inoculated with S typhisuis became pyretic, developed a mild neutrophilia, and had increased serum agglutinating antibody titers, but were clinically normal. Lesions were not present, and S typhisuis was not isolated from 2 group-1 pigs that were killed and necropsied on postinoculation day 8. Then, the antimicrobial agents were withdrawn from the feed of the remaining 8 pigs for 6 days. The pigs were reinoculated with S typhisuis on postinoculation day 16 and developed mild clinical disease with sustained high rectal temperatures. Severe necrotizing typhlocolitis and ulcerative proctitis were found at necropsy in all 8 of the pigs. Similar findings were induced in 7 additional pigs (group 2) that were concurrently inoculated with S typhisuis, but that had no previous exposure to S typhisuis. Successful isolation of S typhisuis required special care and media.
Effect of estradiol and progesterone on antistaphylococcal activity of neutrophils from ovariectomized mares
Authors: Strzemienski Paul J. , Dyer Robert M. , Kenney Robert M.
Published: February 2025

Neutrophils isolated from jugular blood of ovariectomized mares were studied for the effect of estradiol and progesterone on bactericidal activity against Staphylococcus aureus. In experiment 1, neutrophils obtained from 4 mares were tested for bactericidal activity by adding estradiol (43 pg/ml) or progesterone (6.4 ng/ml) to the bactericidal assay. In experiment 2, 3 of the 4 ovariectomized mares were given 2 mg of estradiol, im, daily for 3 days. Eighteen days after the initial estradiol injection, mares were given 300 mg of progesterone, im, for 6 days. Neutrophils from these mares were tested for bactericidal activity 4 days after the initial estradiol injection, 17 days after the initial estradiol injection (control), and 7 days after the first progesterone injection.

Bactericidal activity was measured at 30 and 120 minutes by counting the number of colony-forming units remaining. Neutrophil antistaphylococcal activity was not altered by adding estradiol and progesterone to the assay or by supplementing ovariectomized mares with estradiol and progesterone (P > 0.05).
Biologie characterization of canine melanoma cell lines
Authors: Wolfe Lauren G. , Oliver Julian L. , Smith Bonnie B. , Toivio-Kinnucan Maria A. , Powers Robert D. , Brawner William R. , Henderson Ralph A. , Hankes Gerald H.
Published: February 2025

Eight canine melanoma cell lines were established from tissues from 6 dogs with spontaneous primary or metastatic melanomas. Cell lines were characterized for morphologic features and growth patterns on plastic, pigmentation, ultrastructure, cloning efficiency in soft agar, and tumorigenicity in nude mice. Biologic properties of cell lines were distinct and preserved during 40 to 120 passages in vitro. All cell lines were clonogenic and tumorigenic.