bluuebunny/crossref_metadata_2025 huggingface dataset:
Prophylactic efficacy of an ivermectin sustained-release bolus against challenge exposure with gastrointestinal and pulmonary nematode infective larvae in calves
Authors: Alva-Valdes R. , Wallace D. H. , Egerton J. R. , Benz G. W. , Gross S. J. , Wooden J. W. , Reuter V. E.
Published: February 2025

Twelve Holstein calves were used to determine the prophylactic efficacy of ivermectin against challenge exposure with gastrointestinal and pulmonary nematodes. Two groups of 6 calves (mean body weight, 205 kg) each were formed by restricted randomization according to body weight. Group-1 calves served as nonmedicated controls. Each calf of group 2 was orally given one prototype sustained-release bolus designed to deliver ivermectin at a continuous daily dose of 8 mg. Third-stage nematode infective larvae were given to the calves on posttreatment days 28 and 42. The calves were euthanatized 77 or 78 days after treatment. Ivermectin was 100% effective (P < 0.05) in preventing the establishment of infection by Haemonchus placei, Ostertagia ostertagi, Cooperia spp (C punctata, C oncophora, C surnabada), Nematodirus helvetianus, Oesophagostomum radiatum, and Dictyocaulus viviparus and was > 99% effective against Trichostrongylus axei. Incidental infection by Trichuris spp was reduced by 94% (P = 0.08).
Use of the sustained-release morantel bolus in stocker calves in southern United States
Authors: Craig T. M. , Field R. W. , Rupp G. P.
Published: February 2025

Two groups of 21 mixed-breed heifers were wintered on separate permanent pastures. Each heifer from one group was administered a sustained-release morantel bolus on October 7 (day 0), and the other group remained as untreated controls. Body weights were determined and fecal samples were taken at 28-day intervals. At the onset of the trial and at every 56 days, 6 heifers were removed from each group for slaughter to determine the developmental stages and the number of gastrointestinal nematodes. In addition, 3 tracer calves that were free of gastrointestinal nematodes were released on each pasture for 28 days at the beginning of the trial and after the last experimental-group calves had been removed.

The 6 calves slaughtered on day 0 of the trial had a mean of 5,544 gastrointestinal nematodes. Tracer calves released on day 0 and removed on day 28 of the trial acquired 31,143 and 30,530 gastrointestinal nematodes from the pastures containing the treated and control heifers, respectively. Throughout the trial, the number of nematodes in the control calves increased at each sampling date (mean, 126,168 worms), whereas the mean number of worms in the treated heifers was 45,458. Tracer calves placed in the pastures after the 168-day trial acquired significantly more worms (9,632 vs 2,899; P < 0.05) from grazing the pastures with control heifers than from grazing the pastures with treated heifers.

Counts of eggs per gram of feces were significantly different (P < 0.01) between the 2 groups from day 28 through day 112. Beginning at day 28, mean weight gain in the treated calves (45.1 kg) was significantly (P < 0.01) greater during the trial than was the mean weight gain for the control calves (2.5 kg). The use of a sustained-release morantel bolus in calves on winter pasture in the southern United States proved to be of value on the basis of fewer nematodes acquired and improved weight gains.
Energy balance and growth rate of outbred and inbred male guinea pigs
Authors: Liu C. T.
Published: February 2025

Water intake, food consumption, growth rate, and rectal temperature were measured daily for 14 days and oxygen uptake was determined weekly for 3 weeks in healthy outbred (Hartley stock) and inbred (strains 2 and 13) male guinea pigs. Body weights ranged from 300 to 465 g, and ages were approximately 6 to 10 weeks. Strain-13 guinea pigs had the lowest daily body weight gain (3.27 ± 0.33 g), when compared with strain-2 (4.04 ± 1.21 g) and Hartley guinea pigs (5.72 ± 1.08 g). Outbred guinea pigs also had highest values of water intake and water/food intake ratio(s), and had significantly (P < 0.05 and 0.01) lower oxygen uptake values than did inbred guinea pigs. The ratio of daily average body weight gain to the corresponding daily retained calories, with or without corrections of body surface area (0.05 m2), was higher in Hartley stock than in the strain-13 guinea pigs. Rectal temperatures and food consumption were similar in all guinea pigs. Data indicated that the outbred Hartley guinea pig had a faster growth rate and appeared stronger physiologically, compared with inbred strains.
Effects of ventriculectomy, prosthetic laryngoplasty, and exercise on upper airway function in horses with induced left laryngeal hemiplegia
Authors: Shappell Kristie K. , Derksen Frederik J. , Stick John A. , Robinson N. Edward
Published: February 2025

Effects of ventriculectomy and prosthetic laryngoplasty on upper airway flow mechanics and blood gas tensions in exercising horses with induced left laryngeal hemiplegia were assessed. Five adult horses were trained to stand, trot (4.5 m/s), and gallop (7.2 m/s) on a treadmill (6.38° incline). Inspiratory and expiratory airflows (, , respectively) were measured using a 15.2-cm diameter pneumotachograph in a face mask. Inspiratory and expiratory transupper airway pressures (PuI, PuE, respectively) were determined as pressure differences between barometric pressure and lateral tracheal pressure. Blood collected from exteriorized carotid arteries was analyzed for PaO2, PaCO2, pH, hemoglobin (Hb) content, and HCO3− values. Heart rate (hr) was determined with an hr monitor. Measurements were made with horses standing, trotting, and galloping before left recurrent laryngeal neurectomy (lrln; base line), 14 days after lrln, 30 days after ventriculectomy (44 days after lrln), and 14 days after prosthetic laryngoplasty (58 days after lrln).

Before lrln (base line), increasing treadmill speed for horses from standing to the trot and gallop progressively increased hr, respiratory frequency, , , PuI, PuE, Hb, and PaCO2 values and decreased PaO2, pH, and HCO3− values; inspiratory and expiratory impedances were unchanged. After lrln, inspiratory impedance and PuI were significantly (P < 0.05) increased in horses at the trot and gallop, and PaCO2 was significantly increased in horses at the gallop. The and respiratory frequency were significantly (P < 0.05) decreased in horses at the gallop. Left recurrent laryngeal neurectomy had no effect on PuE, , hr, PaO2, pH, Hb, or expiratory impedance values. Ventriculectomy failed to improve upper airway flow mechanics induced by lrln, whereas prosthetic laryngoplasty restored upper airway flow mechanics to base-line values.
Effects of T-2 mycotoxin ingestion on phagocytosis of Aspergillus fumigatus conidia by rabbit alveolar macrophages and on hematologic, serum biochemical, and pathologic changes in rabbits
Authors: Niyo K. A. , Richard J. L. , Niyo Y. , Tiffany L. H.
Published: February 2025

Rabbits were given T-2 mycotoxin orally at 0, 0.25, 0.5, and 0.75 mg/kg of body weight/day for 21 days. Only rabbits in the 0.75 mg/kg/day group (4 of 5 rabbits) died. Alveolar macrophages were harvested on day 22 and used for in vitro phagocytosis of killed Aspergillus fumigatus conidia. Cultures included sera from untreated rabbits or rabbits treated with T-2. Phagocytosis was significantly (P < 0.01) reduced in cultures that used serum from rabbits treated with 0.5 mg of T-2/kg/day and alveolar macrophages from untreated rabbits or rabbits treated with T-2. There was little reduction in phagocytosis when alveolar macrophages from rabbits treated with T-2 and normal serum were used. Ingestion of 0.5 mg of T-2 toxin/ kg/day significantly (P < 0.05) reduced weight gain, serum alkaline phosphatase activity, serum sorbitol dehydrogenase activity, and serum bacteriostasis. Similar changes were found in the 0.75 mg/kg/day group, as well as a significant (P < 0.05) reduction in pcv, total wbc, and differential leukocyte counts. Neutrophil counts decreased, but not significantly (0.05 < P < 0.10). Significant changes were not detected in alanine transaminase activity, aspartate transaminase activity, blood urea nitrogen concentration, or complement hemolytic activity. Histopathologic changes consisting of centrilobular hepatocellular swelling, mild portal and periportal fibrosis and lymphocyte necrosis within secondary lymphoid tissues developed in most rabbits treated with T-2. Thymic atrophy, bile duct reduplication, and lymphocyte depletion of secondary lymphoid tissues developed in the group given 0.75 mg/kg/day. Severity of lymphoid depletion in secondary lymphoid tissues was greatest in the appendix and decreased in the following order: appendix > sacculus rotundus > ileal Peyer patches > lymph nodes and spleen.

In this study, we provide additional data showing that, at these oral doses of T-2 toxin, rabbits could be immunosuppressed, as evidenced by reduced alveolar macrophage phagocytosis and histopathologic changes in lymphoid tissues. Also, these doses caused reductions in weight gain, certain hematologic factors, and serum alkaline phosphatase and sorbitol dehydrogenase activities.
Frequency of isolation of environmental mastitis-causing pathogens and incidence of new intramammary infection during the nonlactating period
Authors: Oliver S. P.
Published: February 2025

Quarter samples (n = 6,328) of mammary secretions were collected from 160 cows during physiologic transitions of the udder to determine the frequency of isolation of mastitis-causing pathogens and the incidence of new intramammary infections (imi) during the nonlactating period. None of the cows in the herd was infected with Streptococcus agalactiae, and the prevalence of Staphylococcus aureus was low. Cows were not treated with antibiotics at cessation of milking. A threefold increase in the percentage of quarters infected with major mastitis-causing pathogens developed from late lactation to early involution. Coliforms and streptococci other than Str agalactiae accounted for 94% of major pathogen infections. The number of quarters infected with coagulase-negative staphylococci increased slightly from late lactation to early involution, whereas the number of quarters infected with Corynebacterium bovis decreased markedly. Major pathogens caused 101 of 153 imi at parturition and > 90% were caused by streptococci and coliforms. At parturition, 51 of 52 minor pathogen imi were caused by coagulase-negative staphylococci. During early lactation, there was a marked decrease in quarters infected with major pathogens; however, the number of quarters with major pathogen imi during early lactation was 2.3 times higher than the number of quarters infected before cessation of milking. The number of quarters with minor pathogen imi during early lactation was the same as at parturition, but a marked decrease in quarters infected with coagulase-negative staphylococci and a marked increase in C bovis imi developed from parturition to early lactation.
Isolation and comparative restriction endonuclease dna fingerprinting of equine herpesvirus-1 from cattle
Authors: Crandell Robert A. , Ichimura Hiroshi , Kit Saul
Published: February 2025

Deoxyribonucleic acid fingerprinting analyses with 4 restriction endonucleases (EcoRI, BamHI, BglII, and HindIII) and serotest results have definitively indicated that 5 herpesviruses isolated from 1974 to 1986 from aborted bovine fetuses and from bovine tissues and nasal secretions were abortigenic subtypes of equine herpesvirus type 1 (ehv-1). The herpesviruses, designated BH1247, 3M20-3, G118, H1753, and 9BSV4, were neutralized by ehv-l-specific antiserum and could be propagated in cultures of either bovine or equine cells. Only minor differences in restriction endonuclease patterns were detected from the pattern of an Army 183 isolate of ehv-1 subtype 1 that had been passaged only in equine cells and from that of an attenuated ehv-1 subtype 1 (RQ) strain that had been passaged several hundred times in non-equine cells. The individual differences in the restriction endonuclease fragments of the 5 bovine isolates and the Army 183 and RQ strains mainly were attributable to alterations in the terminally repeated and the unique short nucleotide sequences of the ehv-1 genomes, which are known to be hot spots for deletions and tandem repeats. The BamHI restriction endonuclease pattern of the 1977 bovine isolate H1753 was identical to that of ehv-1 subtype-1 strains responsible for most of the virus abortions in vaccinated horses since 1981. Abortigenic ehv-1 strains have the ability to infect cattle and cause disease under natural conditions.
Comparison of two methods for detection of transmissible gastroenteritis virus in feces of pigs with experimentally induced infection
Authors: van Nieuwstadt A. P. , Cornelissen J. B. W. J. , Zetstra T.
Published: February 2025

An indirect, double-antibody sandwich-type elisa for detection of transmissible gastroenteritis virus (tgev) was developed, using a solid phase of rabbit hyperimmune serum and a pool of 3 antipeplomer monoclonal antibodies to trap and to detect the virus, respectively. The technique was used to detect viral antigen in feces of pigs that had been infected with the virulent Miller strain, the attenuated Purdue strain, or the Erica strain (a Dutch field isolate) of tgev. The results were compared with those of a solid-phase immunosorbent electron microscopy (spiem) technique for virus detection. Both techniques detected shedding of virulent virus in feces obtained from pigs on the first or second day after infection, and virus excretion continued for 6 to 8 consecutive days. Virus shedding started later in pigs infected with the attenuated Purdue strain of tgev and lasted only 2 to 4 days. In comparison with the 2 virulent strains, infection with the attenuated strain appeared to be limited to a smaller portion of the small intestine. Of 242 fecal specimens that were tested by use of elisa and spiem, 119 had positive results in both tests. Additionally, virus could be detected by elisa in 21 and by spiem in 16 specimens. Fecal specimens obtained from pigs before infection always reacted negatively by elisa for tgev antigen; there was no cross-reactivity with fecal specimens containing porcine rotavirus or porcine epidemic diarrhea virus. The elisa and spiem were found to be specific and sensitive for the detection of tgev in feces.
Induction of nasal turbinate atrophy in germ-free pigs, using Pasteurella multocida as well as bacterium-free crude and purified dermonecrotic toxin of P multocida
Authors: Kamp E. M. , Kimman T. G.
Published: February 2025

To establish the role of the dermonecrotic toxin (dnt) of Pasteurella multocida in the cause and pathogenesis of atrophic rhinitis, germ-free pigs were inoculated with several strains of P multocida, crude dnt, or purified dnt. In some experiments, the aforementioned inocula were combined with Bordetella bronchiseptica.

All dnt-producing P multocida strains induced severe turbinate atrophy. Histologic examination of the remnants of the nasal turbinates revealed intact, but undulated, ciliated epithelium and numerous osteoclasts. Inflammation was minimal or absent.

A dnt-producing B bronchiseptica strain induced only mild turbinate atrophy. The lesions were characterized histologically by loss of cilia and ciliated cells and by an infiltration of predominantly mononuclear cells. Bone formation seemed impaired. Turbinate lesions were most severe in pigs infected with a combination of B bronchiseptica and a dnt-producing P multocida strain.

Intranasal administration of sterile dnt-containing culture filtrate of P multocida or purified dnt of P multocida did not result in turbinate atrophy. In contrast, turbinate atrophy developed when these preparations were injected im or when intranasal administration of dnt was preceded by inoculation of B bronchiseptica.
Molecular cloning of fragments of the channel catfish virus (Herpesviridae) genome and expression of the encoded mRNA during infection
Authors: Bird R. Curtis , Nusbaum Kenneth E. , Screws E. Allen , Young-White Robert R. , Grizzle John M. , Toivio-Kinnucan Maria
Published: February 2025

Eleven EcoRI dna fragments from the genome of an isolate of channel catfish virus (ccv) were cloned into the bacterial vector pUC19. The cloned dna fragments ranged in size from approximately 200 base pairs to > 5,400 base pairs and accounted for about 13.5% of the 130,000-base pair ccv genome. Nine of these ccv dna fragments encoded sequences that were expressed during late ccv infection. Channel catfish (total length, 4 cm) injected with ccv expressed ccv mRNA at detectable amounts in ≥ 1 tissues. Uninjected control fish failed to express ccv-specific mRNA or expressed ccv-specific mRNA at lower amounts because of the presence of endogenous ccv. Tissue samples from clinically normal channel catfish fingerlings from 2 other farms as well as from adult brood stock also expressed ccv-specific mRNA. The results suggest that ccv can persist in a dormant or transcriptionally active state without causing clinical disease.
Pathogenesis of Mycobacterium bovis infection in American bison
Authors: Thoen Charles O. , Throlson Kenneth J. , Miller Lyle D. , Himes Elmer M. , Morgan Ronald L.
Published: February 2025

Eighteen 12-month-old bison were randomly placed in each of 3 groups (6 animals/group): group-1 bison were exposed to live Mycobacterium bovis, group-2 bison were inoculated with killed M bovis in oil, and group-3 bison were noninfected controls. Six, 6-month-old, tuberculin test-negative calves were placed (pen contact) with group-1 bison 30 days after exposure to M bovis. Tuberculin skin test responses (caudal fold and/or comparative cervical) were detected in all bison in groups 1 and 2 at 2, 4, 6,10, and 12 months. Tuberculin skin test responses were observed in 2 of 6 calves at 9 and 11 months after pen contact with M bovis-exposed bison (group 1). Statistically significant lymphocyte blastogenic responses to M bovis purified protein derivative were detected in group-1 bison exposed to live M bovis at 2 months after exposure (P < 0.025). Significant elisa reactions were detected in sera of bison at 2 months after exposure to killed M bovis in oil (P < 0.005) and in bison 2 months after exposure to live M bovis (P < 0.01). Significant tuberculin skin responses, elisa reactions, or lymphocyte blastogenic responses to M bovis purified protein derivative were not observed in the 6 control bison. Grossly visible tuberculous lesions were observed in lymph nodes and/or lung collected at necropsy in 4 of 6 bison at 12 months after exposure to live M bovis. Microscopic granulomas compatible with tuberculosis were detected in 5 of 6 bison; M bovis was isolated from tissues of each of the 6 bison. Grossly visible lesions were not detected in pen-contact calves at necropsy; M bovis was not isolated.
Cortical somatosensory-evoked potentials in the horse
Authors: Strain George M. , Taylor D. Scott , Graham Margaret C. , Kamerling Steven G.
Published: February 2025

Cortical somatosensory-evoked potentials (sep) were recorded from thoracic and pelvic limbs in 15 horses (13 Thoroughbreds and 2 Quarter Horses). Ulnar nerve sep were evoked by electrical stimulation of the lateral palmar branch of the ulnar nerve at the level of the metacarpophalangeal joint. Recordings were taken between electrodes at 2 cm lateral to the vertex (contralateral to the stimulated limb) and the midpoint of the interorbital line. Four peaks were found in all recordings: N1, P1, N2, and P2. Latencies to the peaks were 39.0 ± 2.7, 45.5 ± 5.3, 50.4 ± 5.2, and 62.3 ± 3.7 ms (mean ± sd), respectively. Tibial nerve sep were evoked by stimulation of the lateral plantar nerve branch of the tibial nerve at the level of the metatarsophalangeal joint. Recordings were taken between electrodes at the vertex (contralateral to the stimulated limb) and the midpoint of the interorbital line. Four peaks were also found in all tibial nerve sep recordings: N1, P1, N2, and P2. Latencies to the peaks were 64.6 ± 11.8, 84.5 ± 9.7, 121.2 ± 11.6, and 134.0 ± 11.1 ms, respectively. Amplitude variability was high for the ulnar nerve and the tibial nerve sep. There was no effect of sex seen on peak latency or amplitude, and peak latencies were not affected by body length.
Comparison of Po2, Pco2, and pH in blood collected from the femoral artery and a cut claw of cats
Authors: Solter Philip F. , Haskins Steve C. , Patz John D.
Published: February 2025

A technique for collection of blood samples from the cut claw of the cat was developed. Forty-six blood samples were collected simultaneously from the cut claw and the femoral artery of 7 healthy cats. Blood gas and pH values were measured and compared. There was no difference between sample pairs for blood Po2 and Pco2, but the pH values were significantly (P < 0.001) higher in the capillary samples (7.432 ± 0.033) than in the samples from the femoral artery (7.419 ± 0.031).
Electrocardiographic values from clinically normal, anesthetized ferrets (Mustela putorius furo)
Authors: Bone L. , Battles A. H. , Goldfarb R. D. , Lombard C. W. , Moreland A. F.
Published: February 2025

Electrocardiograms were recorded from 25 clinically normal male ferrets anesthetized with ketamine and xylazine and from 7 ferrets anesthetized with ketamine alone. Ferrets anesthetized with ketamine alone had excessive salivation, open eyes, muscle tremors, muscle twitching, paddling motions, attempts to stand, and an unstable ecg baseline. Because ketamine/xylazine combination resulted in induction and good muscle relaxation, the ecg had little interference resulting from muscular movement.
Pharmacokinetics of sodium cephapirin in lactating dairy cows
Authors: Prades Marta , Brown Murray P. , Gronwall Ronald , Miles Nancy S.
Published: February 2025

Sodium cephapirin was administered (10 mg/kg of body weight, im) at 8-hour intervals in 4 consecutive doses to each of 6 lactating dairy cows. Blood, normal milk, mastitic milk, urine, and endometrial tissue samples were collected serially. Mean peak cephapirin concentrations in serum were 13.3 μg/ml 10 minutes after the 1st injection and were 15.8 μg/ml 20 minutes after the 4th injection (post[initial]injection hour [pih] 24.33). The overall elimination rate constant value was 0.66/h and plasma clearance was 760 ml/h/kg. Mean peak cephapirin concentration in normal milk was 0.11 μg/ml at pih 2 and mean peak cephapirin concentration in mastitic milk was 0.18 μg/ml at pih 4. Cephapirin was not detected in the endometrium. The highest concentration of cephapirin in urine was 452 μg/ml, 2 hours after the 4th dose (pih 26).
Mycotoxicosis caused by aerosolized T-2 toxin administered to female mice
Authors: Thurman J. D. , Creasia D. A. , Trotter R. W.
Published: February 2025

Thymus, spleen, adrenal glands, and small intestine of female mice exposed to aerosolized T-2 mycotoxin were examined at postexposure hours (peh) 0.25, 1, 2, 4, 6, 9, 12, and 24. Lymphocyte necrosis was observed at peh 1 in the thymus, spleen, and lamina propria and Peyer patches of the small intestine. Necrosis of small intestinal crypt epithelial cells was observed at peh 2, and necrosis of parenchymal cells and increased number of neutrophils were seen in sinusoids of the adrenal cortex at peh 4. These results indicated that the earliest microscopic evidence of T-2 mycotoxicosis after aerosol exposure was necrosis of lymphocytes in the thymus, spleen, and lamina propria and Peyer patches of the small intestine.
Dexamethasone-induced serum biochemical changes in goats
Authors: Maddux Jeanne M. , Moore William E. , Keeton Kerry S. , Shull Robert M.
Published: February 2025

Dexamethasone was administered at sequential dosages of 0.1 mg/kg/day for 3 days and 1 mg/kg/day for 3 days to 6 adult female goats. The greatest effects induced were hypokalemia, hypophosphatemia, and hyperglycemia. At low dosages of dexamethasone, transient increases (P < 0.05) developed in serum sodium and chloride concentrations. An effect on hepatic physiology or iron metabolism was not observed.
Relationship between serologic recognition of Escherichia coli 0111:B4 (J5) and clinical coliform mastitis in cattle
Authors: Tyler Jeff W. , Cullor James S. , Osburn Bennie I. , Bushnell Robert B. , Fenwick Brad W.
Published: February 2025

Serum IgG1 elisa titers recognizing gram-negative core antigens (Escherichia coli [J5]) were studied at a large dairy in central California. Population mean log10 titer was 2.7357 (equivalent to 1:544) with a se of 0.03843. Titers increased with increased lactation number (unstandardized regression coefficient = 0.06733). Changes in lactation number accounted for only 6.77% of titer variation. Titers < 1:240 were associated with 5.33 times the risk of clinical coliform mastitis. Also, older cattle were at greater risk to develop clinical coliform mastitis. These factors apparently affect incidence in a nonlinear fashion, with greatly increased risk associated with titers < 1:240 and with fourth or greater lactations.
Combined Kirschner-Ehmer apparatus and dorsal spinal plate fixation of caudal lumbar fractures in dogs: Biomechanical properties
Authors: Shores Andy , Nichols Chad , Koelling H. A. , Fox W. R.
Published: February 2025

The strength and rigidity of a new surgical technique for the stabilization of caudal lumbar fractures in dogs, using a Kirschner-Ehmer apparatus and a dorsal spinal plate (ke/dsp), were compared with 2 other methods of internal spinal fixation and with intact (control) spines, using a spinal test system that subjected the spines to 4-point bending. The fixation devices were applied to isolated canine lumbosacral spines (L1 to S3) from cadavers. A complete spinal separation was made in the spine implant specimens at L5-L6 by sharp dissection of all ligamentous structures connecting the two vertebrae. Bending moment vs L5-L6 angular deformation curves, and rigidity and load sustained at 10° angular deformation (failure) were recorded for each fixation method and for the control spines. Values were compared by statistical analysis. The combined ke/dsp fixation and a combined vertebral body plate/dorsal spinal plate (vbp/dsp) fixation were stronger and more rigid than were the control spines and those fixed with a modified segmental-fixation method (P < 0.05). There were no statistical differences in strength and rigidity between the 2 combined-fixation techniques. Although the vbp/dsp technique is not applicable to clinical caudal lumbar (L5-L6) fractures, it was compared in this study to the ke/dsp technique because a similar vbp/dsp technique was reported strongest in a similar study of L3-L4 simulated fractures, compared with 3 other spinal-fixation techniques that have been used in repair of caudal lumbar fractures. The technique has been used successfully in 6 dogs with caudal lumbar fractures.
Use of pulsatile intravenous administration of gonadotropin-releasing hormone to induce fertile estrus in bitches
Authors: Cain Janice L. , Cain Gary R. , Feldman Edward C. , Lasley Bill L. , Stabenfeldt George H.
Published: February 2025

The pulsatile iv administration of gonadotropin-releasing hormone (GnRH) was evaluated as a method to induce fertile estrus in 8 anestrous Beagle bitches. Bitches received 1.25 μg of GnRH every 90 minutes for 11 to 13 days. Gonadotropin-releasing hormone was delivered by use of an automatic pump. Reproductive history was known for all bitches, 4 of which, on the basis of 3 or 4 preceding cycles, had an interestrous interval of 219 ± 14 days (mean ± sem). Estrus induction was attempted during early anestrus in 6 bitches (ie, 148 ± 10 days since the preceding estrus) and late anestrus in 1 bitch (ie, 260 days since the preceding estrus); another bitch had not had an estrous cycle for nearly 2 years before GnRH administration. Signs of estrus were seen within 16 days after the start of GnRH administration in the bitches with regular estrous cycles (group 1, n = 7), and within 23 days in the bitch (group 2) with prolonged anestrus. All bitches were bred, and 7 of 8 (87.5%) became pregnant, with a mean litter size of 4.5 ± 0.75. A normal hormonal response pattern was observed in group-1 bitches—a peak increase in plasma estrogen concentration of 22.3 ± 2 pg/ml immediately before the onset of estrus. Peak plasma progesterone concentration (17.3 ± 3 ng/ml) was observed 1 to 14 days after the onset of diestrus in the group-1 bitches that ovulated, and adequate plasma progesterone concentration was maintained throughout gestation. The group-2 bitch also had a similar hormonal response pattern, but the onset of estrous cycle events was delayed, compared with that in group-1 bitches. Her plasma estrogen concentration peaked (16.1 pg/ml) 20 days after starting GnRH administration, and her plasma progesterone concentration peaked (25.8 ng/ml) on the second day of diestrus. The bitch (group 1) that did not conceive apparently did not ovulate (ie, had low plasma progesterone concentration), and her subsequent fertility was not altered. Adverse clinical signs attributable to GnRH treatment were not observed.
Effects of weaning on diarrhea caused by enterotoxigenic Escherichia coli in three-week-old pigs
Authors: Sarmiento Juan I. , Dean Evelyn A. , Moon Harley W.
Published: February 2025

We attempted to determine whether weaning is required for induction of diarrhea in pigs with postweaning enterotoxigenic Escherichia coli infection. Three-week-old newly weaned pigs and their suckling littermates were inoculated with the K88+ enterotoxigenic E coli strain M1823B. Fourteen of 21 weaned and 12 of 20 suckling pigs were genetically resistant to intestinal adhesion by the K88+ strain of E coli; they remained healthy, and gained weight at similar rates. Both groups of K88-resistant pigs gained weight faster, and shed fewer bacteria of strain M1823B in their feces, than did their K88-susceptible counterparts. Diarrhea developed in K88-susceptible pigs in the weaned (6 of 7 pigs) and suckling (4 of 8 pigs) groups, and 1 of the 4 affected suckling pigs died from complications resulting from diarrhea. The incidences of diarrhea, weight gain rates, and the numbers of strain M1823B shed in feces of susceptible weaned and suckling pigs were not significantly (P > 0.05) different. Diarrhea scores of susceptible weaned pigs were significantly (P < 0.02) higher than those of susceptible suckling pigs on the second day after inoculation. In this experimental model, it was concluded that weaning is not required for induction of diarrhea, but may modestly increase its severity.
Effects of an orally administered live Escherichia coli pilus vaccine on duration of lacteal immunity to enterotoxigenic Escherichia coli in swine
Authors: Moon Harley W. , Rogers Douglas G. , Rose Rebecca
Published: February 2025

Primigravid swine were vaccinated orally with a live enterotoxigenic Escherichia coli (etec) strain that produces pilus antigen K99. The titers of K99 antibody in colostrum and milk of vaccinates remained higher than those of nonvaccinated controls through the first lactation after vaccination (4 weeks). Some control swine had low titers of K99 antibody in colostrum or developed low titers of K99 antibody in milk during lactation. Lacteal K99 antibody titers of vaccinates dropped to control levels during the second lactation, 6 months after vaccination. Pigs suckling vaccinates and controls were equally susceptible to challenge exposure to K99+ etec during the second lactation. Orally vaccinated swine given a parenteral booster vaccination (with killed K99+ etec) during their second gestation had K99 antibody in milk through their second lactation. During the second lactation, these orally vaccinated parenterally revaccinated swine had higher titers of K99 antibody in postcolostral milk than did nonvaccinated controls, controls given only the parenteral booster injection, or controls vaccinated parenterally during both gestations.
Use of monoclonal antibodies to serotype-specific antigens of Haemophilus pleuropneumoniae serotype 2 in passive immunization
Authors: Korvuo Armi , Lindberg Lars-Axel , Tuomi Jaakko , Schröder Jim
Published: February 2025

The prophylactic value of mouse monoclonal antibodies to the pig pathogen Haemophilus pleuropneumoniae was studied. Approximately 250 mg of purified mouse monoclonal antibody specific to capsular antigens of H pleuropneumoniae serotype 2 was given iv to five 9-week-old pigs. Five additional pigs from the same litter served as controls. On the following day, all pigs were given a lethal dose (5 × 109) of H pleuropneumoniae serotype 2 into the trachea. Four controls and 1 pig that was given antibodies died within 24 hours. The surviving 5 pigs developed typical signs of pleuropneumonia. After 6 days, the pigs were euthanatized and their respiratory tracts were examined for pathologic changes. All 5 pigs had pathologic changes, but they were less severe in the 4 pigs that had been given antibodies, compared with those in the control pig.
Efficacy of febantel against abomasal nematodes and lungworms in cattle
Authors: Williams J. C. , Marbury K. S. , Eddi C. S. , Willis E. R. , Luther D. G.
Published: February 2025

The efficacy of febantel at a dosage of 5 mg/kg (45.5% paste formulation) against inhibited early 4th-stage larvae (EL4) of Ostertagia ostertagi, other nematodes of the abomasum, and Dictyocaulus viviparus was investigated in 4- to 6-month-old Holstein calves that grazed on pasture heavily contaminated with parasites from February 24 to April 1, 1986 (36 days). In Louisiana, this is the first month of a 3-month period in which increasing numbers of inhibition-prone O ostertagi larvae are acquired, and infection risk with D uiviparus may remain high. Three of 4 calves that died of lungworm infection during the pasture-exposure period were necropsied. Large numbers of abomasal nematodes, including inhibited O ostertagi larvae, and large numbers of D uiviparus were recovered. Twenty-five calves were randomly allotted by equal distribution of body weight to 2 groups and treated on April 4: placebo-treated calves (n = 13) and febantel-treated calves (n = 12). Equal numbers of treated and control calves were killed at 6 and 7 days, respectively, after treatment. Mean numbers of O ostertagi in control cattle were: adults, 4,931; developing 4th-stage larvae (DL4), 1,119; and inhibited EL4, 3,410. Ostertagia lyrata, Trichostrongylus axei, Haemonchus sp, and D viviparus were well distributed in nearly all control calves. Percentage reduction of O ostertagi in treated calves, when compared with controls, was: adults, 83.6%; DL4, 57.8%; and inhibited EL4, 34.8%. Percentage reductions of other species were: O lyrata, 92.6%; T axei adults, 99.3%, and 4th-stage larvae (L4), 100%; Haemonchus sp adults, 66.7%, and L4, 64%; D viviparus adults 90.6%, and immature forms, 97.1%. It was concluded that the poor efficacy against adults of Haemonchus sp and O ostertagi may have been attributable to the high numbers of DL4 and EL4 of both species. In the 6- to 7-day interval between treatment and slaughter, the DL4 could have reached the adult stage and replaced adults lost through treatment.
Efficacy of morantel sustained-release bolus in control of gastrointestinal nematodes of weaned calves during the autumn-winter grazing season
Authors: Stuedemann J. A. , Ciordia H. , Walstrom D. J. , McCampbell H. C.
Published: February 2025

A 168-day study was conducted to evaluate the efficacy of morantel tartrate sustained-release bolus (msrb) in controlling gastrointestinal parasitism in weaned calves during autumn-winter grazing in the temperate climate of southern United States. Sixty-two weanling Angus heifers were used to assess treatment differences. Six sentinel heifers were necropsied to assess pretrial gastrointestinal worm counts. The remaining 56 heifers were assigned to 4 groups of 14 heifers each and were placed on four 4.86-hectare dormant Bermuda grass pastures (1 group/pasture) that had been no-till interseeded with cereal rye in early October. Heifers in 2 groups were given 1 msrb in early November; the other 2 groups served as nonmedicated controls. Three heifers (principals) from each of the 4 groups were necropsied on posttreatment days 57, 112, and 168 (end of study) for total worm recovery. Eight 5-month-old tracer steers, raised worm-free from birth, grazed the 4 pastures (2/pasture) for the first 21 days of the study and then were kept in drylot for 21 days before being necropsied. Level of larval contamination of pastures grazed by control and msrb-treated heifers were comparable, because the mean number of nematodes recovered from tracer steers grazing the control and msrb pastures were 47,449 and 53,835, respectively. At 28 days after treatment, msrb-treated heifers had lower (P < 0.05) mean egg counts/g of feces than did control heifers (280 vs 13). Although the magnitude of the differences between treated and control heifers decreased as the study progressed, the differences were significant (P < 0.05) at each sampling date throughout the 168-day study. Necropsy of 6 sentinels revealed a mean nematode count of 43,135. Necropsy of principal heifers revealed higher mean worm counts in control heifers, compared with those in msrb-treated heifers on day 57 (35,758 vs 2,113; P < 0.05), 112 (20,740 vs 13,764; P = 0.15), and 168 (27,252 vs 6,957; P < 0.05). There were no differences in average daily weight gain between control and msrb-treated heifers (0.53 and 0.53 kg, respectively) over the duration of the study. However, msrb significantly (P < 0.05) reduced egg counts and actual worm numbers during the entire 168-day autumn-winter grazing study.
Anthelmintic efficacies of fenbendazole, ivermectin, and levamisole against Nematodirus battus infections in lambs
Authors: Zimmerman Gary L. , Hoberg Eric P. , Rickard Lora G. , Bishop Janell K.
Published: February 2025

Anthelmintic efficacies of fenbendazole, ivermectin, and levamisole were evaluated against naturally acquired infections of Nematodirus battus in lambs. Four groups of 10 lambs each were used. Oral administration of 8 mg of levamisole/kg of body weight or 5 mg of fenbendazole/kg significantly (P < 0.01) reduced the degree of infection by N battus (adults) by > 99%. An oral formulation of 200 μg of ivermectin/kg was 98% effective (P < 0.01). Numbers of other Nematodirus spp (including N filicollis and N spathiger) were significantly reduced.
High concentration of serum gastrin immunoreactivity and abomasal mucosal hyperplasia in calves infected with Ostertagia ostertagi and/or Trichostrongylus axei
Authors: Snider T. G. , Williams J. C. , Karns P. A. , Markovits J. E. , Romaire T. L.
Published: February 2025

Parasite-free, 4-month-old-calves were inoculated with Ostertagia ostertagi and/or Trichostrongylus axei, followed 6 weeks later by inoculation with increasing doses of O ostertagi for 8 weeks in the 2 groups (n = 4) of calves that had been given O ostertagi. Gastrin immunoreactivity concentration in serum was measured before and after infection and was correlated with changes in mucosal thickness.

Gastrin immunoreactivity concentration in preinoculation control sera ranged from 95.2 to 287.1 pg/ml, and increased values were measured in all parasitized calves after 15 weeks. Significantly (P < 0.05) increased serum gastrin immunoreactivity concentration compared with the preinfection value, was found in calves infected with O ostertagi or T axei, and highly significant (P < 0.01) values were observed in calves infected with both parasites. Abomasal mucosal hyperplasia was observed in all parasitized calves; increased mucosal thickness and mucosal cross-sectional area were most prominent in calves infected with O ostertagi and T axei.
Histochemical study of normal and collapsed tracheas in dogs
Authors: Dallman Mark J. , McClure Robert C. , Brown Esther M.
Published: February 2025

Tracheas from 15 toy breed dogs with normal tracheas and 6 dogs with collapsed tracheas were examined histologically and histochemically. Tracheal cartilage was analyzed for chondroitin sulfate by means of alcian blue (CEC method) and for calcium with alizarin red S. Cartilage arcs from dogs with collapsed tracheas had areas that were apparently hypocellular, and some had other areas that appeared like fibrocartilage or fibrous tissue. Histochemically, collapsed tracheal cartilage had less chondroitin sulfate and calcium than did normal tracheal cartilage. Cartilage arcs from the collapsed tracheas were not uniformly affected to the same degree, and parts of a given tracheal arc appeared normal, whereas other parts had an abnormal histologic appearance.
Ultrasonography of umbilical structures in clinically normal foals
Authors: Reef Virginia B. , Collatos Chrysann
Published: February 2025

The umbilical arteries, urachus, and umbilical vein were scanned ultrasonographically in 13 clinically normal foals that ranged in age from 6 hours to 4 weeks. Sonograms were obtained using a 7.5-MHz sector scanner transducer placed across the midline of the ventral portion of the foal’s abdominal wall. The umbilical vein was scanned from the umbilical stalk to its entrance into the hepatic parenchyma. The mean (± sd) diameter of the umbilical vein was 0.61 ± 0.20 cm immediately cranial to the umbilical stalk, 0.52 ± 0.19 cm midway between the umbilicus and liver, and 0.6 ± 0.19 cm at the liver.

The urachus and umbilical arteries were scanned from the umbilical stalk to the apex of the urinary bladder and had a mean total diameter of 1.75 ± 0.37 cm at the bladder apex. The umbilical arteries also were scanned along either side of the bladder and had a mean diameter of 0.85 ± 0.21 cm.

These measurements and the ultrasonographic appearance of the internal umbilical structures from clinically normal foals can be used as references to diagnose abnormalities of the umbilical structures in neonatal foals.
Efficacy of levamisole against immature and mature nematodes in goats with induced infections
Authors: Coles Gerald C. , Giordano Debra J. , Tritschler Joseph P.
Published: February 2025

Anthelmintic efficacy of levamisole against induced infections with 7- and 21-day-old Haemonchus contortus, Ostertagia circumcincta, Trichostrongylus axei, and T colubriformis was evaluated as an oral drench in goats. Group 1 (n = 8) was not treated, group 2 (n = 8) was given 3.96 mg of levamisole/kg of body weight, group 3 (n = 8) was given 7.92 mg of levamisole/kg, and group 3 (n = 7) was given 11.88 mg of levamisole/kg. Efficacy against all worms was low in goats given 3.96 mg of levamisole/kg, but was high against adult H contortus (99%) and adult T colubriformis (99.7%) in goats given 7.92 mg of levamisole/kg. Although efficacy against adults of all species was high in goats given 11.88 mg of levamisole/kg, some immature worms of all species remained in the abomasa of goats.
Human-parathormone assay for use in dogs: Validation, sample handling studies, and parathyroid function testing
Authors: Torrance A. G. , Nachreiner R.
Published: February 2025

Ten commercially available parathormone (pth) assays were competitively validated, using dilutional parallelism, intra-assay and interassay coefficients of variation, and sensitivity and measured responses of 2 dogs to calcium and edta infusions. A 2-site immunoradiometric assay for intact human-pth was superior to the others for estimating canine-pth, met the criteria for validity, and was further investigated. A series of sample-handling studies was performed. Serum and plasma samples stored at 24 C lost 15% (n = 5; P < 0.05) of pth between 2 and 24 hours. This did not occur at 6 C. The mean pth concentration of sera from blood samples clotted at 24 C was 6% (P < 0.05) higher than equivalent edta samples. Serum samples stored at 6 and 37 C deteriorated 35% and 100% (n = 5; P < 0.05), respectively, after 1 week, whereas samples stored at −20 and −70 C for 4 weeks did not deteriorate. There was no significant deterioration of pth in samples frozen (−40 C) and thawed up to 7 times (n = 5). Parathyroid function testing was investigated by use of 2-hour infusions of disodium edta (25 mg/kg/h), 10-minute infusions of calcium gluconate (3 mg of elemental calcium/kg/10 min), and physiologic saline controls (n = 8). Renal function was monitored before and after edta infusion by exogenous creatinine clearance. Infusion of disodium edta increased mean pth concentration from 67 (time 0) to 317 and 235 pg/ml at 90 and 180 minutes, respectively (P < 0.001). Infusion of calcium gluconate decreased mean pth concentration from 84 (time 0) to 14 and 12 pg/ml at 15 and 60 minutes, respectively (P < 0.005). There were no observable side effects of the infusions in normal conscious dogs and no differences in exogenous creatinine clearance sifter edta infusion.
Effects of glycolytic and cytoskeletal inhibitors on phagocytic and nitroblue tetrazolium reductive activities of bovine neutrophils
Authors: Silva Indira D. , Jain Nemi C.
Published: February 2025

Phagocytic and oxidative metabolic activities of bovine blood neutrophils were determined in the presence of glycolytic (NaF) and cytoskeletal (colchicine, cytochalasin B, and prostaglandin E1) inhibitors. Phagocytosis and post-phagocytic oxidative metabolic activity, measured by nitroblue tetrazolium reduction were determined using zymosan, Escherichia coli, Staphylococcus aureus, or Streptococcus agalactiae. Sodium fluoride (1.25 μM to 1.25 mM concentrations) did not significantly (P < 0.05) inhibit phagocytosis of S aureus and Str agalactiae, whereas phagocytosis of zymosan and E coli was significantly (P < 0.05) inhibited only at 1.25 mM concentration. Colchicine at 1.25 nM to 1.25 μW concentrations significantly inhibited phagocytosis of zymosan and E coli, but not of S aureus and Str agalactiae. Cytochalasin B at 1.25 nM to 1.25 μM concentrations significantly inhibited phagocytosis of zymosan and all 3 bacteria, whereas prostaglandin E1 was noninhibitory at similar concentrations. Nitroblue tetrazolium reduction, in general, was not significantly affected by NaF and cytoskeletal inhibitors.
Seasonal Influence on Estrous Activity in Sows and Gilts
Authors: Hurtgen John P. , Leman Allen D. , Crabo Bo
Published: February 2025

Seasonal fluctuations in the estrous activity of sows after weaning and of sows and gilts after mating were determined by analysis of breeding records from eight swine herds covering a total of 19 herd-years of data. Of 11,461 sows, 78.4% were in estrus within 7 days after weaning. From July through September, 68.6% of sows returned to estrus within 7 days after weaning, compared with 82.0% during the remaining 9 months of the year. An increase in postweaning anestrus of more than 30 days' duration also occurred during summer months. Seasonal fluctuations in the frequency of postweaning estrus were similar for sows moved from farrowing facilities to environments with or without specialized temperature control features. For sows confined to crates after weaning, the rate of postweaning return to estrus was 10.4% greater than for sows in group-housing systems, but the seasonal pattern in post-weaning return to estrus was not altered. Postweaning estrous failure was more obvious in primiparous sows than in multiparous sows, especially during summer and fall. The frequency of delayed return to estrus after infertile mating was 63.7% for matings during the period July through September and 29.7 % for the period January through March.

It was concluded that postweaning and postservice estrous activities in swine are influenced by season of the year and by parity. Group housing of sows or individual crating of sows, and water sprinkling or evaporative cooling systems in the postweaning breeding area, as used in the herds investigated, appear to be of questionable value in preventing estrous failure during summer and fall months.
Craniolateral Approach to the Canine Elbow for Repair of Condylar Fractures or Joint Exploration
Authors: Turner Thomas M. , Hohn R. Bruce
Published: February 2025

A craniolateral approach to the canine elbow was developed. It provides for direct visualization of the distal humeral articular surface, thus facilitating precise repair of condylar fractures. Inasmuch as the primary supporting ligamentous and tendinous structures are not incised, a stable postoperative joint with normal range of motion can be achieved.