bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of monensin pretreatment on tryptophan-induced acute bovine pulmonary edema and emphysema
Authors: Hammond Andrew C. , Carlson James R. , Breeze Roger G.
Published: February 2025

Monensin has been shown to prevent acute bovine pulmonary edema and emphysema (abpe) by reducing ruminal conversion of l-tryptophan (trp) to 3-methylindole (3MI). This experiment was conducted to determine whether monensin must be present in the rumen at the time of exposure to trp to inhibit 3MI production and trp-induced abpe. Two groups each of 3 grade Hereford cows were used in a switch-back experiment with replacement of 2 animals that died (total of 6 control and 6 pretreated cows). For 2 weeks, each cow was fed 4.5 kg of poor quality alfalfa-brome grass hay/day, plus trace mineralized salt and water ad libitum and a daily supplement of 0.9 kg of ground barley with added monensin (200 mg; group M) or without monensin (group C, controls). Both hay and supplement were equally divided into morning and evening feedings. At the end of the 2-week pretreatment period, supplement feeding was stopped.

Approximately 48 hours after the last supplement feeding of monensin, each cow was given an oral dose of 0.35 g of trp/kg of body weight to induce abpe. Blood plasma and ruminal fluid were obtained at intervals up to 96 hours after trp dosing for analysis of 3MI. At —48 and at 0 hours with respect to trp dosing, ruminal fluid was incubated with trp to determine in vitro 3MI and indole production.

Two group C cows (control; no monensin pretreatment) died of abpe and 1 cow each of the M and C groups had periods of increased rate and depth of breathing. Hemolysis related to high ruminal and plasma indole concentrations developed in 3 group M cows and in 1 group C cow. Hemoglobinuria was observed in 1 group M cow. Mean ruminal 3MI concentrations peaked 18 hours after trp dosing at 203 nmoles/ml and 245 nmoles/ml for group M and group C cows, respectively. These values were not significantly different (P > 0.05), nor were there any differences in mean ruminal 3MI concentrations between treatments at any other time (P > 0.05). Ruminal indole concentrations were higher in group M cows than in group C cows (P < 0.05) at 18 hours after trp dosing, but were not different at other times (P > 0.05). Plasma concentrations of 3MI and indole generally followed ruminal concentrations, but at lower values.

In vitro conversion of trp to 3MI was 25% in ruminal fluid from monensin-pretreated cows contrasted with 50% for control cows' ruminal fluid at the time of supplement withdrawal (P < 0.05). At the time of trp dosing, conversion to 3MI was not different between treatments (P > 0.05). These data indicate that at the dose used, the effects of monensin on ruminal 3MI production are diminished within 48 hours after monensin feeding is stopped. Effective prevention of abpe may require continuous administration of monensin for the critical period of approximately 10 days after cows are exposed to trp or given change of pasture.
Development of pharmacokinetic models for sulfonamides in food animals: Metabolic depletion profile of sulfadiazine in the calf
Authors: Woolley Joseph L. , Sigel Carl W.
Published: February 2025

Pharmacokinetic modeling, the use of a mathematical model to predict tissue concentrations of a compound after measuring plasma concentrations, has been advocated for several sulfonamides to alleviate the regulatory burden and to aid the producer by reducing the number of condemned carcasses resulting from sulfonamide residue contamination. Previous models were developed without detailed knowledge about the metabolism of the drugs in the target species. After completion of a metabolism and tissue residue-depletion study with [14C]sulfadiazine in the calf, the applicability of pharmacokinetic modeling to our data was explored. In the present experiment, each of 4 healthy male calves (∽40 kg) was given 1 bolus ([14C]sulfadiazine, 1.0 g; trimethoprim, 0.2 g) orally for 5 consecutive days. Two calves were killed on day 7 after the last dose, and in the 2 remaining calves, the total radioactivity was monitored in plasma until the levels reached 0.1 mg/L 7 days later (day 14 after the last dose) when that pair was killed. Intact sulfadiazine was eliminated more rapidly from plasma than total radioactivity; plasma sulfadiazine concentrations reached 0.01 mg/L by day 10. The highest concentrations of intact drug were found in the kidney (mean sulfadiazine concentration was 0.07 mg/kg at 7 days after the last dose). Mean total sulfadiazine-derived residues were 0.25 mg/kg of muscle, 0.90 mg/kg of kidney, and 1.27 mg/kg of liver on day 7 and depleted to 0.04, 0.16, and 0.31 mg/kg, respectively, by day 14. The major radioactive solvent-extractable component in tissues on day 14 was identified as 2-benzenesulfonamidopyrimidine, but it accounted for < 1% of the dose of sulfadiazine excreted in the urine. Analysis of these data and review of published sulfonamide residue depletion studies indicated that before a pharmacokinetic model can be developed for regulatory use, the following must be available: (i) a study defining the relationship between the drug, metabolites, and total residues so that the marker compound(s) can be identified, (ii) a sensitive and specific assay for the marker compound so that the tissue-plasma relationship can be defined throughout thei concentration range of interest, and (iii) a reliable estimate of the qualitative and quantitative variations among animals for which the model is being developed.
Experimental leptospiral infections in pregnant cattle with organisms of the Hebdomadis serogroup
Authors: Thiermann A. B.
Published: February 2025

The clinical and pathologic implications of leptospirosis caused by organisms of the Hebdomadis serogroup were tested on 8 pregnant cows. The animals were inoculated after their 5th month of pregnancy, 2 with serovar szwajizak and 6 with serovar hardjo. During the acute phase of the infection, the cows had mild signs of clinical illness; however, mastitis was observed in all cows that calved. One cow aborted, and 2 delivered premature and weak calves.

By bacteriologic cultural examination, a short leptospiremic phase was observed. Leptospires were isolated from milk of 5 cows during early phases of mastitis; these isolations were obtained only when using solid media. Leptospiruria was determined by culture and direct examination. Only hardjo-inoculated cows had detectable urinary shedding which was observed to extend past 450 days in 1 cow.

Leptospires were isolated from tissues of all cows and from 2 calves at necropsy. Interstitial nephritis was observed in all cows necropsied. Histologically, leptospires were demonstrated in silver-stained sections of kidney, liver, and lung of most calves. Leptospires were also observed in sections of kidney of all cows necropsied and in the cotyledons, placenta, and liver of some.

Agglutinating titers were detected in the serum of cows as early as 4 days after inoculation and reached maximum titer (81,920) after 20 days. Significant serum titers persisted for the duration of the experiment only in hardjo-inoculated cows. At birth, all calves had no detectable agglutinins, but seroconverted within 24 hours; the serum titers were similar to those found in the dam's milk.
Organ blood flow and distribution of cardiac output in nonanesthetized swine
Authors: Tranquilli W. J. , Parks C. M. , Thurmon J. C. , Benson G. J. , Koritz G. D. , Manohar M. , Theodorakis M. C.
Published: February 2025

Organ blood flow and distribution of cardiac output (co) were determined in awake resting swine, using radionuclide-labeled 15-μm diameter microspheres. Absolute values of blood flow (per 100-g basis) were determined for various organs and peripheral tissues. Internal organs of the swine, which constituted 8.25 ± 0.79% of the total body mass, received 45.46 ± 2.64% of the resting co. The fraction of co received by brain, heart, kidneys, liver (via hepatic artery), and gastrointestinal tract was 1.13%, 3.04%, 12.95%, 4.27%, and 18.71%, respectively.
Hemostatic changes in dogs with experimental Leptospira interrogans serovar icterohaemorrhagiae infection
Authors: Navarro Carlos E. Kantek , Kociba Gary J.
Published: February 2025

Inoculation of 5 dogs with 4 × 109 Leptospira interrogans serovar icterohaemorrhagiae produced mild to fatal illness. Hemorrhages were detected in 2 dogs. The hemostatic changes included thrombocytopenia and increased circulating fibrinolytic split products.
Fatty acid composition of equine erythrocytes
Authors: Luther D. Gene , Cox Hollis Utah , Dimopoullos G. T.
Published: February 2025

Fatty acid composition of erythrocytes of healthy horses was determined. Three fatty acids (C16:0, C18:0, and C18:1) were found in approximately equal quantities and comprised 72.17% of the total. Nine other fatty acids were found in small amounts. Saturated fatty acids constituted 67.2% of the total. Marked variation was demonstrated in the occurrence and distribution of fatty acids in the sterol ester, triglyceride, phospholipid, and free fatty acid fractions.
Antagonism of xylazine sedation in dogs by 4-aminopyridine and yohimbine
Authors: Hatch Roger C. , Booth Nicholas H. , Clark J. Derrell , Crawford Lester M. , Kitzman Joseph V. , Wallner Barbara
Published: February 2025

Groups of fasted, atropinized crossbred dogs of both sexes were given a standard dosage (2.2 mg/kg of body weight) of xylazine, im. When fully sedated, the dogs were given iv 4-aminopyridine (4-ap; 0.3 mg/kg), yohimbine (0.125 mg/kg), or a combination of 4-ap+yohimbine in weekly trials. Control groups were given saline solution. Two additional groups were given a 5× overdose of xylazine (11 mg/kg), im. When fully sedated, 1 of these groups was given 4-ap+yohimbine, iv; the other group was given saline solution.

In dogs given the standard dosage of xylazine, 4-ap decreased mean walk time (wt; time to cognition and ability to walk on a leash) to 6 minutes (saline-treated groups = 14.1 and 17.8 minutes). Mean total recovery time (trt) was not shortened. Yohimbine decreased wt to 2.2 minutes and decreased trt to 0.4 hours (trt in saline-treated groups = 0.8 and 2.7 hours). In 1 group of control dogs, weekly injections of xylazine caused decreases in normal wt and trt, indicating development of tolerance to xylazine. The combination of 4-ap+yohimbine decreased wt to 1.4 and 1.9 minutes in 2 groups of dogs. The trt in these 2 groups was decreased to 0.5 hours.

In previously untreated dogs given the 5× overdose of xylazine, 4-ap+yohimbine decreased wt to 3.3 minutes (saline-treated group = 73 minutes) and slightly decreased trt to 5.1 hours (saline-treated group = 6.1 hours). Additional doses of 4-ap+yohimbine were not given. Relapses to unconsciousness did not occur in any of the dogs; recovery was characterized by somnolence and easy elicitation of walking.

In 3 dogs anesthetized with xylazine and pentobarbital, the combination of 4-ap+yohimbine iv caused (in order): transient femoral arterial hypotension with tachycardia and increases in respiratory rate, depth, and minute volume; parietal monopolar eeg activation; biceps femoris bipolar electromyogram activation; and behavioral arousal in less than 2 minutes. Increases in heart rate and in respiratory rate and depth (“respiratory lift”) were also observed clinically in intact dogs.

The combination of 4-ap+yohimbine seems to be a safe, highly effective, specific antagonist of xylazine in dogs. The combination may be useful for reversal of the effects of standard dosages and overdoses of xylazine or for arousal of animals anesthetized or overanesthetized by combinations of xylazine with other drugs.
Effect of passive immunization on phagocytosis of blood-borne Escherichia coli in spleen and liver of turkeys
Authors: Arp L. H.
Published: February 2025

Clearance of Escherichia coli from blood and localization in tissues were studied by culture and microscopy in nonimmunized and passively immunized turkeys after iv inoculation. In nonimmunized poults, high mortality was associated with persistence of large numbers of E coli in the blood. In immunized poults, rapid clearance of E coli from blood was associated with large numbers of E coli in hepatic sinusoids and fewer bacteria in the spleen. An electron-dense, fibrillogranular coat covered extracellular E coli in immunized poults, but not in nonimmunized poults. Rapid clearance of virulent E coli from blood was markedly enhanced by antibody-dependent phagocytosis in liver.
Virologic study of the reproductive tract in dairy cows
Authors: Manspeaker Joe E. , Haaland Monica A. , Mohanty Sashi B.
Published: February 2025

From Aug 1, 1979 to Aug 15, 1980, a total of 624 samples were collected from the vaginas, cervices, and uteri of 208 dairy cows 30 to 37 days after parturition. An additional 90 samples were collected from the reproductive tracts from 30 of the 208 cows. The 30 cows had aborted or were repeat breeders. Samples from cows that had aborted were collected within a week after clinical abortion or immediately after rectal palpation revealed subclinical abortion.

All samples were tested for the presence of cytopathogenic viruses. All samples were negative.
Prevalence of parasitism diagnosed by fecal examination in Louisiana dogs
Authors: Hoskins J. D. , Malone J. B. , Smith P. H. , Uhl S. A.
Published: February 2025

The prevalence of canine intestinal parasitism was evaluated by fecal examination of 4,058 dogs admitted to the Louisiana State University Veterinary Teaching Hospital and Clinics from March 1977 to March 1980. One or more species of parasites was identified in 2,048 (50.5%) dogs. Hookworms were encountered in 38.5% of the dogs examined, whipworms in 14.9%, ascarids in 8.5%, coccidia in 2.6%, tapeworms in 2.2%, and giardia in 0.8%. Single parasitic infection was present in 1,456 (35.9%) dogs. For hookworm and whipworm infections, male dogs were significantly (P < 0.5) more often affected, compared with females or spayed females. Ascarid, coccidia, and giardia infections were more prevalent in pups than in mature dogs, whereas whipworm infections were detected less often in dogs < 6 months of age. Hookworms were the most prevalent parasites in male (39.2%) and female (35.7%) dogs < 6 months of age and maintained high prevalence in mature dogs. Tapeworm infections were diagnosed sporadically in all age groups. In female dogs > 24 months of age, significantly less parasitism was present as compared with younger females. In male dogs, the prevalence of parasitism diminished less markedly with increasing age.
Bovine monocyte-induced tumor cell cytotoxicosis
Authors: Atluru D. , Johnson D. W.
Published: February 2025

Human monocytes have been shown to be highly cytotoxic for tumor cells in vitro. To determine whether these observations could be extended to the bovine species, monocyte-induced tumor cell cytotoxicosis was examined in vitro. Target cells were initiated from benign hyperplastic corneal plaque lesions or ocular squamous cell carcinoma lesions in cattle. The monocyte-induced tumor cell cytotoxicosis, as measured by target cell [3H]thymidine incorporation, was highly significant (P < 0.001) in corneal plaque cells at target:effector cell ratios of 1:10, 1:5, and 1:1. The [3H]thymidine incorporation was also highly significant (P < 0.001) in squamous cell carcinoma cells at target:effector cell ratios of 1:10 and 1:5, but of less significance (P < 0.01) at 1:1. Further, the ability of bovine monocytes to kill target cells was enhanced by culturing effector cells for 3 days before assay. These data show that bovine monocytes are cytotoxic for tumor cells in vitro and indicated that bovine monocytes may be of importance in the control of neoplastic proliferation in vivo.
Interferon induction in healthy and tumor-bearing dogs by cell walls of Mycobacterium bovis strain bacille Calmette-Guérin
Authors: Winters Wendell D. , Harris Steven C.
Published: February 2025

High titers of interferon (if) were released into the circulation of 8 of 10 adult, female, healthy dogs (group A) and 7 of 10 pet dogs (group C) bearing naturally occurring primary malignant mammary tumors after they were given a single dose (4 mg/ml) of a Mycobacterium bovis bacille Calmette-Guérin cell wall (bcg-cw) emulsion. This bcg-cw emulsion had been administered into 1 mammary gland in the 10 healthy dogs and intratumorally in the 10 dogs bearing biopsy-confirmed malignant mammary tumors. Increases in if titers were not detected in sera from 10 dogs (group D) bearing malignant mammary tumors injected with placebo, from 10 dogs (group E) after surgical excision of malignant mammary tumors, and from 15 noninjected healthy control dogs (group B). The if detected in the sera of tumor-bearing and healthy dogs following injection of bcg-cw was effective against vesicular stomatitis virus and influenza A virus when tested in Madin-Darby canine kidney cells, but not in human KB cells. Vesicular stomatitis viral antibody was not detected by neutralization tests nor radioimmunoassays in sera from the subjects. At entry into the study of 30 dogs with malignant mammary tumors (groups C, D, and E) and of 25 healthy dogs (groups A and B), titers of if were detected in 14 of the former and in 1 of the healthy dogs. There was no correlation between the pretreatment if titers in tumor-bearing dogs and age, clinical history, breed, previous pregnancies, or tumor volume. In tumor-bearing dogs injected with bcg-cw (group C), there was no apparent relationship between the induction of high titers of if and any previously mentioned factors, the amount of bcg-cw injected, or serum levels of antibody specifically reactive with bcg-cw or canine viral antigens.
Sensitivity of smooth Salmonella cholerae-suis var kunzendorf field strains to antibody complement under various conditions
Authors: Griffith Ronald W. , Kramer Theodore T.
Published: February 2025

Seventy-two field strains of smooth Salmonella cholerae-suis var kunzendorf were obtained from outbreaks of swine paratyphoid. The field strains were examined for susceptibility to killing by antibody-complement (Ab-C) after they were exposed to Tris-EDTA, lysozyme, or saline solution. Considerable differences were found in susceptibility to killing by Ab-C in the strain population. Some strains were highly sensitive to Ab-C under all experimental conditions, whereas others became sensitive only after prior exposure to Tris-EDTA or to lysozyme. One strain was resistant to all treatments. Numerical decrease of colony-forming units by Tris-EDTA affected the population independently of decrease of the colony-forming units by Ab-C in saline solution. Evidence was obtained to indicate that Tris-EDTA may inhibit growth of S cholerae-suis in addition to the documented effect of Tris-EDTA on the release of lipopolysaccharide from the cell wall of gram-negative bacteria.
Ischemia: A cause of hepatic telangiectasis in cattle
Authors: Jensen Rue , Johnson L. W. , Lauerman L. H. , Tucker J. O. , Swift B. L. , Alexander A. F , Hancock H. A. , Flack D. E. , Braddy P. M. , Horton D. P.
Published: February 2025

We histologically examined (i) 73 bovine livers condemned by packing house inspectors for telangiectasis, (ii) 15 bovine livers passed by the same inspectors as normal, and (iii) 8 livers from cattle given an injection into their mesenteric veins: 6 with a suspension of agar particles containing viable Haemophilus somnus and 2 with diluent only. The injected cattle were killed and necropsied 2 to 12 days after the inoculations.

Of the 73 telangiectatic livers, 57 (78%) had thrombosed and occluded or contracted and empty portal veins (venopathies), whereas 1 of the 15 normal livers contained one microscopic focus of telangiectasis and nearby venopathy. Of the 6 livers injected with suspended particles, all had venopathies and telangiectasis and the 2 control livers had neither.
Prevalence of bovine herpesvirus-1, bovine viral diarrhea, parainfluenza-3, bovine adenoviruses-3 and -7, and goat respiratory syncytial viral antibodies in goats
Authors: Fulton Robert W. , Downing Marian M. , Hagstad Harry V
Published: February 2025

Sera from healthy goats were collected during October 1979 through October 1980. These sera were tested for bovine herpesvirus-1 (bhv-1), bovine viral diarrhea virus (bvdv), parainfluenza-3 (pi-3) virus, bovine adenoviruses (bav) -3 and -7, and goat respiratory syncytial virus (grsv) antibodies by microtitration virus-neutralization test. The number of herds with seropositive goats for each virus were: 5/38 (13.2%) for bhv-1; 9/38 (23.7%) for bvdv; 8/38 (21.1%) for pi-3 virus; 1/38 (2.6%) for bav-3; 15/38 (39.5%) for bav-7; and 26/34 (76.5%) for grsv. Seropositive rates for each virus for the individual goats tested were: 6/502 (1.2%) for bhv-1; 9/498 (1.8%) for bvdv; 49/458 (10.7%) for pi-3 virus; 1/487 (0.02%) for bav-3; 40/448 (8.9%) for bav-7; and 166/332 (50.0%) for grsv.
Systolic time interval recordings as a measure of cardiac function in the healthy rabbit: Reference values
Authors: Long Harry J. , Diamond Sheldon S. , Burningham Richard A. , Raflo Charles P.
Published: February 2025

Results of systolic time interval recordings obtained serially on 104 female New Zealand White rabbits were analyzed for reproducibility, variation with respect to changes in heart rate (hr), and interrelationship of the various systolic time intervals. A table of values for systolic time intervals in the healthy rabbit was constructed. The preejection period (pep), left ventricular ejection time (lvet), and pep/lvet ratio were 0.040 ± 0.008 s, 0.119 ± 0.014 s, and 0.337 ± 0.066 respectively. The major systolic time intervals, pep and lvet, varied with respect to hr according to the regression equations: pep = 0.057 − 0.000078 hr and lvet = 0.175 − 0.000251 hr. The QS2 interval, S1S2 interval and isovolumic contraction time also varied with changes in hr.
Effectiveness of ivermectin against later 4th-stage Strongylus vulgaris in ponies
Authors: Slocombe J. O. D. , McCraw B. M. , Pennock P. W. , Vasey J.
Published: February 2025

Twelve pony foals were reared worm-free and inoculated with Strongylus vulgaris. Approximately 8 weeks after they were inoculated, 6 foals were given ivermectin im at a dosage rate of 200 μg/kg of body weight and 6 were given a placebo. All foals were necropsied 35 days after treatment. Ivermectin was 98.9% effective in eliminating later 4th-stage S ulgaris larvae located near the origin of major intestinal arteries and in reducing clinical signs and permitting resolution of lesions associated with verminous arteritis.

One pony foal reared on pasture and with evidence of arteritis of the cranial mesenteric and ileocolic arteries on arteriography was treated with ivermectin at a dosage rate of 200 μg/kg of body weight. On arteriographs taken subsequently, there was evidence of regression of the lesion, and at necropsy 9 weeks after treatment, there was no arteritis or larvae in those arteries.
Effect of infectious bovine rhinotracheitis virus immunization on viral shedding in challenge-exposed calves treated with dexamethasone
Authors: Rossi Charles R. , Kiesel George K.
Published: February 2025

Calves not vaccinated with infectious bovine rhinotracheitis virus (ibrv) became latently infected when challenge exposed and treated with dexamethasone (dm). Calves that shed ibrv after dm treatment were considered to be latently infected. Vaccination with a temperature-sensitive intranasal vaccine or with formalinized ibrv in Freund's complete adjuvant (ibrv-fca) protected some, but not all, calves against latent infection—indicating a role for the immune response in preventing latent infection. That all latently infected calves were not detected after dm treatment was indicated by the fact that after a 2nd dm treatment of 3 calves treated 6 months previously and not found to shed virus, 1 of the calves was latently infected. Latently infected calves were inoculated with successive doses of ibrv-fca and treated with dm. Nonvaccinated calves shed virus, whereas vaccinated calves similarly treated did not shed virus. Because both groups had a comparable cell-mediated immune response, as determined by blastogenic response to ibrv, but the vaccinated group had significantly higher virus-neutralizing antibody titers, a role for humoral antibody in preventing viral shedding was indicated.
Effect of an intramammary polyethylene device in primiparous dairy cows
Authors: Jaster E. H. , Smith A. R. , McPherron T. A. , Pedersen D. K.
Published: February 2025

A sterilized polyethylene intramammary device (imd) was inserted through the papillary duct into a front and a rear mammary quarter of 12 primiparous dairy cows, which were mastitis-free. This study was conducted during lactation from month 1 postpartum to completion (generally month 9). After the device was inserted, milk somatic cell counts (scc) increased. Milk scc in the quarters fitted with imd from foremilk, primary, and stripping samples were 5.2, 2.6, and 5.9 × 105 cells/ml, respectively. Comparable counts for control quarters were 2.1, 1.4, and 3.6 × 105 cells/ml. The scc in foremilk from the quarters fitted with the device were 2 to 3 times greater than the counts in foremilk from control quarters during month 2 and subsequent months of lactation. The scc were significantly increased in primary and stripping samples from quarters fitted with imd; however, the scc of 2.6 × 105 cells/ml in primary milk would not affect market milk quality.

Milk production for the lactation was decreased (0.6 kg/quarter/day) in the quarters fitted with imd in comparison with control quarters throughout the lactation. There were no differences in percentages of milk fat or protein between deviced and control quarters.

Conductivity values were increased in foremilk and stripping samples, but not in primary samples, for the quarters with imd. Bovine serum albumin concentrations were also increased.
Antibody-dependent cell-mediated cytotoxicity in pigs
Authors: Zarkower A. , Eskew M. L. , Scheuchenzuber W. J. , Ferguson F. G. , Confer F.
Published: February 2025

Development of antibody-dependent cell-mediated cytotoxicity (adcc) was studied in cells obtained from porcine fetal and neonatal tissues. Pulmonary washouts, hepatic tissues, splenic tissues, and neutrophil fractions of blood were sources of cells. Neutrophils from fetuses and newborn pigs had high levels of adcc activity, whereas the cells obtained from the other organs had highest activity shortly after the pig was born; in the case of pulmonary and hepatic cells, activity decreased by 84 hours following birth of the animal. The increased adcc activity in tissues of pigs after birth appeared to coincide with increasing numbers of neutrophils in the various tissues.
Experimentally induced porcine proliferative enteritis in specific-pathogen-free pigs
Authors: Lomax Larry G. , Glock Robert D. , Hogan John E.
Published: February 2025

Thirty-three, 10-week-old, specific-pathogen-free pigs were randomly allotted to 3 treatment groups: group 1—intragastrically given homogenized intestinal mucosa (crude inoculum) from pigs with naturally occurring proliferative enteritis; group 2—given cultures of Campylobacter sputorum subsp mucosalis; and group 3—controls. One pig from each group was killed 4, 7, 10, 14, 18, 21, 24, 28, 31, 36, and 38 days after inoculation. The earliest intestinal lesion observed in groups 1 and 2 was leukocytic exudate within crypt lumina and focal inflammation of the surrounding lamina propria. The lesions occurred primarily over ileal aggregated lymphoid nodules (Peyer's patches). These changes were followed by focal proliferation of immature crypt epithelial cells and infiltration of increasing numbers of macrophages into the lamina propria. Campylobacter splike organisms were observed within the cytoplasm of affected epithelial cells by light and electron microscopies. Lesions progressed to diffuse crypt cell proliferation, elongation of crypts, and loss of villi. Mucosal necrosis was not a prominent feature.
Tissue changes in dogs fed a zinc-deficient ration
Authors: Sanecki R. K. , Corbin J. E. , Forbes R. M.
Published: February 2025

Six-week-old puppies fed a corn-soy based zinc-deficient diet developed lesions of parakeratosis, mild hyperkeratosis, alterations in germinal epithelium, erosions, ulcerations, vesiculation, alopecia, and inflammation of the skin. These changes were prominent in the skin of dependent regions, in areas of stretch and friction, and external contact. The epithelial lesions were reversible by adding zinc to the diet, with complete remission of external lesions by 6 weeks.
Brain edema and gliopathy induced by 6-an i lonicotinamide intoxication in the central nervous system of rats
Authors: Sasaki Satoshi
Published: February 2025

Brain edema was produced by 6-aminonicotinamide (6-an) in the rat with accompanying metabolic disturbance due to the accumulation of an antimetabolite of nicotinamide in the cns. Twenty-four hours after intraperitoneal administration of 6-an, significant (P < 0.01) increases of solium and water in the medulla oblongata were observed. By electron microscopy, the lesion was characterized by swelling of the perivascular neuroglial processes, producing disturbances of the active transport in the cell membrane and increased pisocytosis in the endothelial cells, especially of the arterioles and venules. The metabolic inhibitor was shown to produce not only an increased water and sodium uptake in neuroglias, which is characteristic of cytotoxic brain edema, but also produced protein-rich edema in the extracellular space, ie, vasogenic brain edema. The protein transport in the metabolic disturbance caused by 6-an was traced, using horseradish peroxidase, revealing that it occurred from the vasculature into the extracellular spaces via pinocytotic vesicles due to the change in the cerebrovascular permeability.
Influence of photoperiod on the pregnant and postpartum mare
Authors: Hodge S. L. , Kreider J. L. , Potter G. D. , Harms P. G. , Fleeger J. L.
Published: February 2025

Over a 2-year period, mares (n = 32) of predominantly Quarter Horse breeding and their foals were used to study the effects of photoperiod on reproduction during the periparturient period. Specific objectives of the study were (i) to evaluate the effects of an extended photoperiod regimen (16 hours' light) on gestation length, foal development, and postpartum reproductive performance, and (ii) to measure changes in plasma progesterone concentrations during the last trimester of gestation and plasma luteinizing hormone (lh) concentrations after foaling until ovulation.

Mares in the extended daylength treatment group had shorter (10 days) mean gestation length (P < 0.01) than did control mares (exposed to normal daylight hours). Although foals of mares exposed to long photoperiod were carried for a shorter term, their birth weights tended to be heavier, but not significantly, than those of foals from control mares. Foal size, as determined by body measurements, was not affected by the photoperiod. Neither interval from parturition to 1st ovulation nor onset of estrus to ovulation were significantly affected by the extended photoperiod. Plasma progestogen concentrations increased from basal levels at prepartum weeks 4 and 5 to peak values a week before foaling in both mare groups. The lh profiles from parturition to ovulation were similar for both mare groups. However, mean plasma lh values during the 7 days before the 1st ovulation were higher (P < 0.05) in mares exposed to extended daylength than in control mares.
Effects of oral and injectable tetracyclines on bacterial drug resistance in feedlot cattle
Authors: Stabler Susan L. , Fagerberg Diane J. , Quarles Carey L.
Published: February 2025

Enteric bacteria isolated from feedlot heifers treated with tetracyclines (tet) were examined for resistance to tet and ampicillin. The effects of feeding (45 days) therapeutic and subtherapeutic quantities of chlortetracycline (ctc) and the injection of therapeutic doses of oxytetracycline (3 daily doses) were compared.

Performance data from the 45-day trial did not identify an antibiotic effect on average daily gain, although cattle fed subtherapeutic quantities of ctc showed improved feed efficiency.

Bacterial resistance to tet was increased in the heifers given the therapeutic and subtherapeutic quantities of ctc in the ration. However, an increase in resistance to ampicillin did not occur. Oxytetracycline injections had a shortterm effect, increasing the number of resistant organisms jnly during the week of drug administration.
Lysates of turkey-grown Pasteurella multocida: Partial solubilization of the cross-protection factor(s)
Authors: Brogden K. A. , Rimler R. B.
Published: February 2025

A lysate of turkey-grown Pasteurella multocida was treated to determine the nature of a cross-protection factor cpf). Complete lysate was treated with proteolytic enzymes and mild heat. Cross protection was not induced with pepsin-treated lysate, but 50% cross protection was induced with trypsin-treated lysate and 100% cross protection was induced in turkeys vaccinated with lysate heated at 56 C or 1 hour. Complete lysate was also fractionated by differential and sucrose density gradient centrifugation. After the lysate was centrifuged for 1 hour at 100,000 × g, the cpf was found in the supernatant and pellet fractions, indicating that the cpf was dispersed throughout; 84% of the lysate protein was in the supernatant and 14.7% of the protein in the pellet. After sucrose density gradient centrifugation, 100% cross protection was induced with the top and bottom gradient fractions and 60% with the middle fraction. Although the differential centrifugation pellet and bottom sucrose gradient fraction had protein that was disproporonately small when compared with the soluble portions of the whole lysate, they had the cpf equal in immunizing capacity.
Model infection of the chicken embryo with Haemophilus somnus
Authors: Nward Jeanne L. , Ward G. E. , Stevens J. B. , Maheswaran S. K.
Published: February 2025

Infectious thromboembolic meningoencephalitis of cattle which is caused by Haemophilus somnus has been difficult to study due, in part, to lack of model infection in a laboratory animal. Model infection was induced in 12-day-old chicken embryos after iv injection of H somnus. Death with typical lesions (hemorrhage, degeneration of brain, congestion of venules with leukocytes and meningitis) was seen in the chicken embryo between 2 and 6 days after injection of organisms. Bacteria could be demonstrated in lesions, using Warthin-Starry silver stain.

Three stable colonial variants of H somnus were cultured from dead embryos. They appeared as small translucent (st), small opaque (so), and large opaque (lo). Lethal dose50 values of st was 4.4 × 104; for so, 3.6 × 104; and for lo, 8 × 106. Statistical analysis indicated that st and so were significantly more lethal (P < 0.001) than lo.
Pharmacokinetics and tissue concentrations of tylosin in selected avian species
Authors: Locke Diana , Bush Mitchell , Carpenter James W.
Published: February 2025

Tissue and plasma concentrations and the biological half-life of tylosin in avian species of a variety of body sizes and metabolic rates were studied. The species chosen were eastern bobwhite quail (Colinus virginianus virginianus), pigeons (Columba livia), greater sandhill cranes (Grus canadensis tabida), and emus (Dromaius novaehollandiae). In the 1st phase of this study, tylosin was administered im to quail, pigeons, and emus at a dosage rate of 25 mg/kg of body weight and to cranes at a dosage rate of 15 mg/kg. The average peak plasma concentrations of tylosin in quail, pigeons, cranes, and emus were 4.31, 5.63, 3.62, and 3.26 μ/ml, respectively. These peak concentrations occurred at 0.5 to 1.5 hours after administration. The biological half-life of tylosin averaged 1.2 hours in quail, pigeons, and cranes, and was 4.7 hours in emus.

In the 2nd phase of this study, tylosin concentrations in the tissues of quail, pigeons, and cranes were markedly higher than were plasma concentrations at corresponding sampling times. Six hours after antibiotic administration, tissue concentrations of tylosin in all species remained within the minimum inhibitory concentration for most pathogenic organisms.

Dosage regimens of 25 mg of tylosin/kg 4 times daily for quail and pigeons, 15 mg/kg 3 times daily for cranes, and 25 mg/kg 3 times daily for emus would be needed to establish and maintain therapeutic tissue concentrations.
Prevalence of antibodies to Haemophilus pleuropneumoniae in Iowa swine
Authors: Schultz R. A. , Young T. F. , Ross R. F. , Jeske D. R.
Published: February 2025

The prevalence of complementfixing (cf) antibodies to Haemophilus pleuropneumoniae in Iowa swine was determined by testing samples collected randomly from each of 9 cropreporting areas (9 to 12 counties) in Iowa in approximate proportion to the number of swine marketed annually from each area. For testing, a pooled antigen composed of serotypes 1 to 5 of H pleuropneumoniae was used in a modified direct Microtiter complement-fixation test. Of 7,348 sera tested, 2,362 or 32.1% had cf antibodies (titer ≥ 1:4) to the organism. On a herd basis, 417 of 597 herds or 68.8% had at least 1 animal with cf antibodies (titer ≥ 1:4) to the organism. The clinical problem with H pleuropneumoniae has become significant in recent years, but by no means is the overt disease as prevalent as animals or herds with cf antibodies to the organism.
Influence of modified protein diets on electrolyte, acid base, and divalent ion balance in dogs with experimentally induced chronic renal failure
Authors: Polzin David J. , Osborne Carl A. , Stevens Jerry B. , Hayden David W.
Published: February 2025

The influence of a maintenance diet (44.4% dry weight protein) and 2 reduced protein diets (8.2 and 17.2% dry weight protein) on acid-base, electrolyte, and divalent ion balance of dogs with experimentally induced chronic renal failure was studied for 40 weeks. Moderate-to-severe hyperchloremic metabolic acidosis developed in dogs fed the 8.2% protein diet, but not in the groups fed the 17.2% and 44.4% protein diets. Serum sodium and potassium concentrations were not altered significantly by the diets. Mean serum calcium concentrations increased significantly in the 3 groups after renal failure was induced; however, serum calcium concentration generally did not exceed the normal range. Dogs fed reduced protein diets had smaller serum magnesium and phosphorus concentrations than did the dogs fed the maintenance diet.

Microscopic alterations in bone morphology consistent with canine renal osteodystrophy were not detected after 40 weeks of renal failure in dogs fed the 8.2% protein diet, but were detected in dogs fed the 17.2% and 44.4% protein diets. Examination of skull radiographs of the dogs prepared 40 weeks after renal failure was induced revealed that the lamina dura dentes were visible in all groups.

It was concluded that the 8.2% protein diet was of therapeutic benefit in management of altered divalent ion metabolism in dogs with chronic renal failure. However, the high frequency of concomitant acidosis indicated that appropriate alkalinization therapy should be included with this diet. Adverse effects of feeding the 17.2% protein diet were not detected. However, it was less effective than the 8.2% protein diet in minimizing development of hypermagnesemia and skeletal changes consistent with renal osteodystrophy.
Aqueous vasopressin response test in clinically normal dogs undergoing water diuresis: Technique and results
Authors: Hardy Robert M. , Osborne Carl A.
Published: February 2025

Studies were undertaken to develop a standard procedure and to establish reference values for an aqueous vasopressin response test in dogs with normal renal function undergoing water diuresis. After iv administration of 5 mU of aqueous antidiuretic hormone (adh)/0.45 kg of body weight to 13 water-loaded clinically normal dogs, the mean urine specific gravity increased from 1.002 ± 0.001 to 1.021 ± 0.0058; the mean urine osmolality increased form 99 ± 52 mOsm/kg of water to 933 ± 252 mOsm/kg. The pcv, total plasma protein concentrations, and serum osmolalities decreased in all dogs during waterloading and adh administration, but slowly returned toward base-line values after discontinuing the adh infusion.
Repositol vasopressin response test in clinically normal dogs undergoing water diuresis: Technique and results
Authors: Hardy Robert M. , Osborne Carl A.
Published: February 2025

Maximal renal concentrating ability after parenteral administration of repositol antidiuretic hormone was evaluated in 13 clinically normal dogs undergoing water diuresis. Urine specific gravity and osmolality progressively increased in all dogs and generally attained maximum concentrations after 8 to 12 hours. Urine specific gravity values increased from a mean of 1.003 ± 0.001 mOsm/kg of water to a mean maximal value of 1.042 ± 0.009 mOsm/kg. Urine osmolality increased from a mean of 132 mOsm/kg to a mean maximal value of 1,518 ± 242 mOsm/kg. Water intoxication was observed in all dogs due to continued administration of water after antidiuretic hormone administration.
Duration of maternally derived immunity to tetanus and response in newborn foals given tetanus antitoxin
Authors: Liu Irwin K. M. , Brown Susan L. , Kuo Jason , Neeley Dean P. , Feeley John C.
Published: February 2025

Serum tetanus antitoxin (tat) concentrations were measured in a group of 30 foals from birth to 4 months of age. Five of 30 foals (16.6%) had serum titers < 0.01 IU of tat/ml by 1 month of age. At 2 months of age, 17 of 28 foals (60.7%) had titers < 0.01 lU/ml. By 3 months of age, 22 of 29 (75.5%) foals tested had titers of < 0.01 IU/ml. At the age of 4 months, 24 of 29 foals (82.1%) had titers of < 0.01 IU/ml.

The tat given to foals at birth resulted in an immediate increase in titer when circulating antitoxin was absent or minimal. Titers considered protective against tetanus resulting from an im injection of exogenous tat at birth were maintained for at least 3 months after the injection.
Effects of the spleen, epinephrine, and splenectomy on determination of blood volume in cats
Authors: Breznock E. M. , Strack D.
Published: February 2025

Blood volume (bv), rbc mass, plasma protein (pp), and pcv were determined in (i) awake, nonsplenectomized (nspx) cats before and after splenic contraction was induced by iv administration of epinephrine, (ii) in pentobarbital-anesthetized, nspx cats before and after splenic contraction was induced by epinephrine and splenectomy, and (iii) in awake, splenectomized (spx) cats before and after epinephrine was administered. Blood volume, absolute rbc mass in the spleen could not be determined accurately in awake or anesthetized, nspx cats. Accurate bv and rbc mass determinations could only be obtained in cats without the spleen; mean bv and rbc mass of awake or anesthetized, spx cats were 4.1% and 1.4% or body weight, respectively.

The spleen was a dynamic sequestering organ for feline erythrocytes (rbc). Epinephrine (0.1 ml of 1:1,000) given iv resulted in the observed contraction of the spleen within 2 minutes. Relaxation of the spleen with rbc uptake began 3 minutes after epinephrine was given and it proceeded at a rate of approximately 0.93% of circulating pcv/min. At 20 minutes after epinephrine was given, a steady state of pcv occurred, and 20% of the maximum circulating pcv observed after the administration of epinephrine was stored within the spleen. At 60 minutes after epinephrine was given to awake, spx cats, intravascular fluid influx of 4 ml/kg resulted in a decrease of pcv and pp. At 3 hours after splenectomy was done, intravascular fluid efflux resulted in hemoconcentration—a calculated fluid deficit of 2.5 ml/kg/hr occurring during the 3 hours after surgical removal of the spleen.
Segmental thoracolumbar spinal (subarachnoid) analgesia in conscious horses
Authors: Skarda R. T. , Muir W. W.
Published: February 2025

A new technique for producing segmental subarachnoid analgesia in adult horses without causing complete loss of locomotor control is described. A 17-gauge Huber point (Tuohy) needle was used to place a catheter with a stylet into the subarachnoid space at the lumbosacral intervertebral space in 13 adult horses (weighing 500 ± 60 kg, representing both sexes) and to advance the catheter craniad to the thoracolumbar area. The position of the catheter was confirmed radiographically. A 2% mepivacaine hydrochloride solution (1.5 ml, 30 mg) was injected through the catheter at a rate of 0.5 ml/60 s. Segmental analgesia, as determined by the horses' responses to superficial and deep muscular pinpricks, occurred within (onset) 5 to 10 minutes of injection and lasted (duration) 42.4 ± 15 minutes (min-max, 25 to 68 minutes). Maximal thoracolumbar analgesia extended from spinal cord segments T12 to L3 on both sides of the spinal column. Subarachnoid injection of mepivacaine hydrochloride caused significant (P < 0.05) increases in heart rate and subcutaneous temperature and decreases in respiratory rate and rectal temperature. Significant changes (P < 0.05) were not observed in a control group of 7 horses after subarachnoidal injection of sterile water (1.5 ml). The surgical application of segmental subarachnoid analgesia was demonstrated in 1 horse. The benefits and potential complications of segmental subarachnoid analgesia in horses are discussed.
Sarcocystosis in newborn calves fed Sarcocystis cruzi sporocysts from coyotes
Authors: Dubey J. P. , Speer Clarence A. , Epling Glenwood P.
Published: February 2025

The development of Sarcocystis cruzi was compared in 3- to 14-day-old calves (n = 38) inoculated with 55,000 to 500,000,000 sporocysts from intestinal scrapings of coyotes, and euthanatized and necropsied on postinoculation days (pid) 4 to 153. From pid 15 to 19, the calves remained clinically normal, except for fever (≥ 40 C), during the development of 1st-generation meronts, and lesions in calves euthanatized at this time were confined mainly to mesenteric lymph nodes and consisted of focal necrosis due to vascular thrombosis. On pid 26, calves became sick, coincident with maturation and rupture of 2nd-generation meronts. In calves euthanatized from pid 26 to 28, the main lesion was hemorrhage in many organs and 1st- and 2nd-generation meronts were located subendothelially in unidentified cells between endothelium and tunica elastica. In calves euthanatized on pid 31, inflammation was pronounced in many tissues; this was also seen in calves euthanatized from pid 31 to 46 and corresponded to individual merozoites and the early development of sarcocysts. Inflammation began to subside by the time sarcocysts were recognizable (pid 67). Nonsuppurative hepatitis occurred in calves euthanatized from pid 15 to 153.
Somatosensory-evoked response of ataxic Angora goats in suspected haloxon-delayed neurotoxicity
Authors: Wilson Richard D. , Witzel Donald A. , Verlander James M.
Published: February 2025

Somatosensory-evoked responses (ser) were recorded in 3 Angora goats with moderate posterior paresis. The cause of posterior paresis was unknown. The goats had recently been given haloxon and had also been grazing in a pasture with carpetweed (Kallstroemia hirsutissima). Haloxon and carpetweed have each been reported to cause posterior paresis in livestock. An electrical stimulus applied subcutaneously in the pelvic limb of the affected goats failed to evoke an ser at the cerebral cortex. Electrical stimulation in the thoracic limb evoked a normal-appearing ser. The absence of ser from pelvic limb stimulation indicated a functional impairment of the somatosensory pathways.