bluuebunny/crossref_metadata_2025 huggingface dataset:
Purification of the phospholipase D of Corynebacterium pseudotuberculosis by recycling isoelectric focusing
Authors: Egen Ned B. , Cuevas William A. , McNamara Peter J. , Sammons David W. , Humphreys Robin , Songer J. Glenn
Published: February 2025

Recycling isoelectric focusing was investigated as a method for purification of phospholipase D (pld) from cultures of Corynebacterium pseudotuberculosis. Supernatant fluids from cultures of equine isolate 155 in brain-heart infusion broth were dialyzed against distilled water, concentrated by lyophilization, and fractionated by preparative isoelectric focusing in free solution in a pH 3 to 13 gradient with 6M urea. Protein concentration, pH, and pld activity of the 10 resulting fractions were determined. Two pld activity assays were used: release of 14C choline from labeled sphingomyelin and synergistic hemolytic activity with Rhodococcus equi factors. Enzyme activity focused in 2 fractions at pH 8.5 to 9.8. The synergistic hemolytic assay was simple and rapid for detecting pld in partially purified fractions. Electrophoretic examination of the fraction containing the highest concentration of pld activity revealed protein bands at 14, 21, and 31.7 kD Mr suggesting purification to near-homogeneity. Proteins from the 31.7-kD band were labeled by antibodies in serum from a goat with chronic C pseudotuberculosis infection.
Udder edema in cattle: Effects of diuretics (furosemide, hydrochlorothiazide, acetazolamide, and 50% dextrose) on serum and urine electrolytes
Authors: Vestweber Jerome G. E. , Al-Ani Falah K. , Johnson Dallas E.
Published: February 2025

Blood and urine chemical values at parturition in clinically normal Holstein cows (n = 12) were compared with the same values in Holstein cows developing udder edema (n = 12). There was no statistically significant mean difference between the 2 groups for the serum and urine chemical data. Furosemide (500 mg) given iv caused a significant increase in serum calcium and sodium, urine chloride, potassium, and sodium, and fractional excretional ratio of chloride, potassium, and sodium. There was a significant mean decrease in the serum potassium, urine creatinine, osmolality, pH, and specific gravity. Hydrochlorothiazide (250 mg) given iv caused a significant mean increase in serum chloride, urine chloride, potassium, and sodium, and fractional excretion ratio of chloride, potassium, and sodium. There was a significant mean decrease in serum potassium and sodium, urine osmolality, pH, and specific gravity. Acetazolamide (500 mg) given IV caused a significant mean increase in blood urea nitrogen, serum chloride and glucose, urine sodium, and fractional excretion ratio of sodium, while causing a significant mean decrease in serum potassium, sodium, and phosphorus, and urine creatinine. Dextrose (500 g) given IV as a 50% solution caused a statistical mean increase in serum glucose, urine chloride, potassium, and sodium, and fractional excretion ratio of chloride and potassium. A statistical mean decrease occurred in the packed cell volume, blood urea nitrogen, serum calcium, potassium, sodium, and phosphorus, urine creatinine, osmolality, and PH.
Pharmacokinetics of phenobarbital in dogs given multiple doses
Authors: Ravis W. R. , Pedersoli W. M. , Wike J. S.
Published: February 2025

Studies were conducted to examine the temporal changes an phenobarbital pharmacokinetics during chronic dosing in dogs. Ten dogs were allotted into 2 groups, administered a single oral dose, rested for 35 days, and then given the drug for 90 consecutive days. After single administration of 5.5 mg/kg of body weight or 15 mg/kg, the total body clearance (Clt/F) was 5.58 ± 1.89 ml/h/kg and 7.28 ± 1.07 ml/h/kg, respectively. The half-lives (t1/2) for the 2 groups were 88.7 ± 19.6 hours for the 5.5-mg/kg dose and 99.6 ± 22.6 hours for the 15-mg/kg dose. Significant differences in Clt/F or t1/2 were not observed between the 2 groups. Multiple-dosing regimens (5.5 mg/kg/day or 11 mg/kg/day) were initiated in the same dogs for 90 days. The Clt/F was significantly (P < 0.05) greater on days 30, 60, and 90 than the single dose for both groups. After the last dose on day 90, several blood samples were obtained to determine phenobarbital t1/2. On day 90, the t1/2 was significantly (P < 0.05) shorter and the Clt/F was significantly greater than single-dose values. The Clt/F and t1/2 were 10.2 ± 1.7 ml/h/kg and 47.3 ± 10.7 hours for the group given the low dose and 15.6 ± 2.5 ml/h/kg and 31.1 ± 4.4 hours for the group given the high dose, respectively. Both Clt/F and t1/2 were significantly (P < 0.05) different between the 2 groups on day 90. Results of the study indicated that single-dose pharmacokinetic studies of phenobarbital do not accurately predict steady-state phenobarbital serum concentrations (Css) because of possible autoinduction. Although considerable variation in phenobarbital pharmacokinetics was detected among dogs, a dose of 5.5 mg/kg/day is recommended for Css of 20 to 25 μg/ml and 11 mg/kg/day for Css of 30 to 40 μg/ml.
Ultrasonographic evaluation of induced testicular lesions in male goats
Authors: Eilts Bruce E. , Pechman Robert D. , Taylor H. Wayne , Usenik Edward A.
Published: February 2025

To study testicular ultrasonographic features, unilateral testicular artery ligation was performed in 12 bucks to induce predictable ischemic necrosis of the testis. Both scrotal testes then were scanned subsequently on days 1, 3, 5,7,15, and 30. On each of the designated days, 2 bucks each were castrated and the excised testes were rescanned outside the scrotum before gross and histologic examinations. In each goat, the testis without the ligated artery served as a control. Gross and histopathologic findings in the testis were compared with ultrasonographic observations. As the study progressed from day 0 to day 15, visually and microscopically, the testis involved in the testicular artery ligation had edema that changed to areas of peripheal necrosis with thickening of the testicular capsule. On day 30, the affected testis had granulation tissue in the areas that previously had been necrotic.

Ultrasonographically, the testicular changes were consistent with the gross and histopathologic findings. There were areas of decreased echogenicity that corresponded to the necrotic areas and foci of high echogenicity that corresponded to areas of tubular mineralization. On day 30, the granulation tissue was difficult to differentiate ultrasonographically from normal testicular parenchyma. Between days 3 and 15, hydrocele was seen ultrasonographically in several goats. The excellent association between ultrasonographic findings and gross and histologic changes suggested that testicular ultrasonography might be a valuable diagnostic tool for assessing testicular disease in domestic animals.
Develoment of an enzyme-linked immunosorbent assay to detect IgG, IgM, and complement (C3) on canine erythrocytes
Authors: Porter Robert E. , Weiser M. Glade , Callahan Gerald N.
Published: February 2025

An elisa was used to detect IgG, IgM, and complement (C3) on the surface of canine erythrocytes. Erythrocytes were placed in wells of a microtitration plate and incubated with affinity purified, alkaline phosphatase-conjugated anti-canine IgG, IgM, or C3. Results of the elisa were compared with the direct antiglobulin test (dat) by preparing standard reference curves from canine blood type A erythrocytes that had been incubated with serial dilutions (1:2 to 1:8,192) of canine anti-A serum. The elisa detected increased erythrocyte-bound immunoglobulin and complement at two- to fourfold dilutions greater than those required for positive results with the dat. The elisa required small sample and reagent volumes and detected lower concentrations of immune components than did the dat.
Early renal ultrasonographic findings in dogs with experimentally induced ethylene glycol nephrosis
Authors: Adams William H. , Toal Robert L. , Walker Michael A. , Breider Michael A.
Published: February 2025

Renal ultrasonographic changes were evaluated in 5 dogs administered 10 ml of commercial antifreeze (95% ethylene glycol)/kg of body weight, po, and in 2 dogs given placebos. Studies were made prior to and after ingestion on an hourly basis over a period of 8 to 10 hours. All dogs were anesthetized immediately after toxin or placebo ingestion for the duration of the study. Renal cortical echogenicity was evaluated in comparison with that of the adjacent liver and spleen. Echogenicity of the renal medulla and definition of the corticomedullary junction were assessed. Within 4 hours after ethylene glycol administration, renal cortical echogenicity of all intoxicated dogs increased from normal to surpass that of the liver and approach or equal that of the spleen. Medullary echogenicity in all intoxicated dogs progressively increased over the course of the study, with changes recognized within 5 hours after ethylene glycol administration. An ultrasonographic pattern consisting of nearly equal, marked increase in cortical and medullary echogenicity and relatively hypoechoic corticomedullary junction and central medullary regions was recognized concurrent with the development of anuria in 3 of the 5 intoxicated dogs.

Mild, transient increases in cortical and medullary echogenicity were oberved in anethetized control dogs. However, no statistical difference (P < 0.05) was detected between baseline, peak, and terminal echogenicity values in these dogs.

Blood and urine samples were collected hourly from intoxicated dogs to coincide with ultrasonographic studies. Most clinicopathologic values derived from these samples were not statistically different (P < 0.05) from those reported in a study that used a similar intoxication protocol in nonanesthetized dogs.
Transstadial and attempted transovarial transmission of Anaplasma marginale by Dermacentor variabilis
Authors: Stich Roger W. , Kocan Katherine M. , Palmer Guy H. , Ewing S. A. , Hair Jakie A. , Barron Selwyn J.
Published: February 2025

Transstadial and transovarial transmission of Anaplasma marginale by Dermacentor variabilis were attempted with ticks exposed to the organism once by feeding as larvae or nymphs, and twice by feeding as larvae and nymphs. Typical colonies of A marginale were in gut tissues of adults that were infected as larvae, larvae and nymphs, and as nymphs; repeated exposure of ticks did not appear to result in an increase in the number of colonies in the gut of subsequently molted adults nor did it affect severity of the clinical disease that developed in cattle they fed on. In contrast, colonies of A marginale were not found in the midgut epithelium of unfed nymphs exposed as larvae, even though companion nymphs transmitted the parasite, causing severe clinical anaplasmosis in susceptible calves. The organism was not transmitted transovarially by F1 larvae or nymphs from the groups exposed as parent larvae, nymphs, larvae and nymphs, and as adults. Some of the calves fed on by F1 progeny had a few erythrocytic marginale bodies that looked suspiciously like A marginale, as well as postchallenge exposure prepatent periods that were longer than other calves in the transovarial transmission study. Sera from these calves were tested for antibody to A marginale, using a highly sensitive immunoblot technique. Antibodies were not detected in any of the sera.
Efficacy of an in-feed ivermectin formulation against gastrointestinal helminths, lungworms, and sarcoptic mites in swine
Authors: Alva-Valdes R. , Wallace D. H. , Foster A. G. , Ericsson G. F. , Wooden J. W.
Published: February 2025

The efficacy of ivermectin as an in-feed formulation was evaluated against naturally acquired gastrointestinal helminths, lungworms, and sarcoptic mites (experiment 1; n = 24) and against induced infection with intestinal nematodes (experiment 2; n = 24) in pigs. Treatments consisted of ivermectin administered in feed at concentrations calculated to provide 100 or 200 μg/kg of body weight/d for 7 days or of nonmedicated feed (controls) for 7 days.

At concentration of 100 μg of ivermectin/kg/d, efficacy against naturally acquired infections was 97.7% for Ascaris suum, 97.8% for Metastrongylus spp, > 99% for Oesophagostomum spp, 100% for Macracanthorhynchus hirudinaceus, and 89.7% for Ascarops strongylina. Against induced infections (fourth-stage larvae), efficacy was 100% for A suum and 96.9% for Oesophagostomum spp.

At concentration of 200 μg of ivermectin/kg/d, efficacy against naturally acquired infections was 100% for A suum, Hyostrongylus rubidus, Metastrongylus spp, and Ascarops strongylina; > 99% for Oesophagostomum spp; and 85.9% for Macracanthorhynchus hirudinaceus. Against induced infections (fourth-stage larvae), efficacy was 100% for A suum and 95% for Oesophagostomum spp.

At concentrations of 100 and 200 μg of ivermectin/kg/d, efficacy against Sarcoptes scabiei var suis was evidenced by elimination of the mite by posttreatment day 14.
Cross-protective immunity between equine encephalomyelitis viruses in equids
Authors: Walton Thomas E. , Jochim Michael M. , Barber T. Lynwood , Thompson Lee H.
Published: February 2025

Eighteen equids were inoculated with eastern equine encephalomyelitis (eee) and 18 equids with western equine encephalomyelitis (wee) viruses to produce eee virus- and wee virus-immunized equids. Twelve surviving eee virus-seropositive equids, 15 surviving wee virus-seropositive equids, and 10 nonimmunized, seronegative equids (controls) were subsequently inoculated with an equine pathogenic (epizootic) strain of Venezuelan equine encephalomyelitis (vee) virus to determine cross-protective immunity. Challenge infection produced 90% mortality in control (nonimmunized) equids, and 40% mortality in wee virus-seropositive equids; all eee virus-seropositive equids survived. Postchallenge exposure vee viremia levels in eee virus- or wee virus-seropositive equids were lower than those in the 10 nonimmunized vee virus-inoculated control equids. Plaque-neutralizing antibody responses to vee virus in the eee virus- and wee virus-seropositive equids were similar in time of onset and titer to the antibody responses of nonimmunized equids. Neutralizing antibody to the third equine encephalomyelitis virus (either eee virus or wee virus) was detectable in 19 of 27 equids after inoculation with the challenge virus, vee. Demonstration of cross-protective immunity between eee or wee virus and vee virus in equids confirmed field observations made during the vee epizootic in Texas in 1971.
Characterization of the attachment of Treponema hyodysenteriae to Henle intestinal epithelial cells in vitro
Authors: Bowden Christine A. , Joens L. A. , Kelley L. M.
Published: February 2025

Propertess of the attachment of Treponema hyodysenteriae to Henle intestinal epithelial (hie 407) cells were examined. The frequency of attachment depended on the motility and viability of the spirochetes. Rabbit hyperimmune and swine convalescent antisera inhibited attachment. Treatment of hie cells with neuraminidase had no effect on attachment; however treatment of spirochetes with the enzyme decreased adherence significantly (P = 0.01). Attachment was inhibited by N-acetylneuraminic acid, d-glucuronic acid, and fetuin. Adherence was increased following coincubation with N-acetylglucosamine or yeast mannan. Surface antigens of T hyodysenteriae, isolated by chemical extraction, competitively inhibited adherence. Concentrated T hyodysenteriae culture supernatant fractions inhibited adherence, but concentrated phosphate buffered-saline washings of the spirochete and concentrated uninoculated media did not inhibit adherence. Sialic acid was detected in unwashed T hyodysenteriae and spent culture supernatant fractions in higher concentrations than from washed spirochetes and uninoculated media. It was concluded that the binding adhesins on T hyodysenteriae for cultured hie cells may contain sialic acid residues.
Effect of surgical manipulation, placental fluid, and flunixin meglumine on fetal viability and prostaglandin F2α release in the gravid uterus of mares
Authors: Pascoe David R. , Stover Susan M.
Published: February 2025

Twenty-one pregnant mares with single or twin conceptuses between 41 and 65 days of gestational age were allotted to 5 treatment groups. A ventral median celiotomy was performed in all mares. In group-1 mares (3 mares, single conceptus), the uterus and fetus were palpated for 5 minutes. In group-2 mares (3 mares, single conceptus, flunixin meglumine), 250 ml of sterile placental fluid was injected into the nongravid uterine horn. In group-3 mares (4 mares, unicornuate twin conceptuses), group-4 mares (3 mares, unicornuate twin conceptuses, flunixin meglumine), and group-5 mares (8 mares, bicornuate twin conceptuses, flunixin meglumine), 1 conceptus was removed from the uterus via hysterotomy. All mares received progesterone prophylactically until day 100 of gestation or until the fetus died.

The 3 mares in group 1 delivered clinically normal, live foals. The mean prostaglandin F2α metabolite (pgfm) plasma concentration peaked at 180 ± 5.2 pg/ml during uterine manipulation and fetal palpation, then declined to baseline by 1 hour. Free placental fluid (group 2) undermined the chorioallantois ventrally and resulted in fetal death witin 3 hours after surgery. The mean pgfm plasma concentration peaked at 39 ± 4 pg/ml following injection of placental fluid. None of the remaining fetuses in the 7 mares with unicornuate twin conceptuses (groups 3 and 4) survived. Five mares with unicornuate twin conceptuses (group 5) delivered single viable foals. In another mare in group 5, the fetus was alive 4 days after surgery, when the mare was euthanatized for a fractured femur. The peak mean pgfm plasma concentration during hysterotomy in the mares not treated with flunixin meglumine(group 3) was 1,979 ± 27.36 pg/ml, and the highest peak mean pgfm plasma concentration in the flunixin meglumine-treated hysterotomized mares (groups 4 and 5) was 123 ± 4.8 pg/ml. Flunixin meglumine was at least 94% effective in inhibiting expected increases in pgfm plasma concentrations associated with hysterotomy.
Enhanced platelet reactivity in heartworm-infected dogs
Authors: Boudreaux Mary K. , Dillon Allen R. , Spano Joseph S.
Published: February 2025

Platelet number, mean platelet volume, and platelet function were evaluated in 34 clinically normal dogs and 28 heartworm-infected (hwi) dogs. Mean platelet numbers for dogs of the hwi group was not significantly lower than those for dogs of the control group (214,000 vs 254,000 cells/μl); however, 6 (21%) hwi dogs had platelet numbers < 150,000/μl, compared with only 2 (6%) heartworm-negative dogs. The mean platelet volume was not significantly different (7.8 vs 7.7 fl) between the 2 groups of dogs. Mean platelet aggregation responses to intermediate and low concentrations of collagen (3.0 and 1.5 μg) and to high, intermediate, and low concentrations of adp (25, 10, and 5 μM) were greater in dogs of the hwi group. Mean platelet 14C-serotonin release was also greater in hwi dogs in response to high concentration of adp (25 μM) and to intermediate concentration of collagen (3.0 μg).
Reference blood chemical values in ostriches (Struthio camelus)
Authors: Levy A. , Perelman B. , Waner T. , van Grevenbroek M. , van Creveld C. , Yagil R.
Published: February 2025

Reference blood chemical values were determined for 65 male and 61 female ostriches (Struthio camelus) 1 month to 72 months of age. Plasma values of glucose, total protein, triglycerides, cholesterol, uric acid, urea, bilirubin, creatinine, osmolality, electrolytes, and enzyme activity were determined. In general, differences in various values appeared mainly among age groups and less so between sexes. Older ostriches had lower plasma glucose values and enzyme activity than did younger ostriches. High plasma sodium and chloride concentrations in young ostriches correlated with high plasma osmolalities. Plasma calcium values were lower in laying ostriches. Uric acid concentrations were markedly higher than were urea concentrations in all ostriches.
Effect of Pasteurella haemolytica infection on the distribution of sulfadiazine and trimethoprim into tissue chambers implanted subcutaneously in cattle
Authors: Clarke Cyril R. , Short Charles R. , Corstvet Richard E. , Nobles Debbie
Published: February 2025

A study was designed to determine the effect of Pasteurella haemolytica infection on the rate and extent of penetration of sulfadiazine and trimethoprim into tissue chambers implanted sc in cattle. Thermoplastic tissue chambers were implanted sc in 6 calves. At 35 days after implantation, sulfadiazine (25 mg/kg of body weight) and trimethoprim (5 mgkg) were administered iv to 5 of the calves. Chamber fluid and blood samples were collected from each animal at various time intervals for 24 hours after administration. Ten days later, all chambers were inoculated with P haemolytica serotype 1. At 36 hours after inoculation, a second pharmacokinetic study was conducted, using sulfadiazine and trimethoprim. Drug doses and sampling schedules were identical to those used prior to inoculation. A histologic study of infected chamber tissue was conducted, using the calf not included in the pharmacokinetic studies. Disposition curves of antimicrobials in serum and chamber fluid were well described by 2-compartment and 1-compartment pharmacokinetic models, respectively. Inoculation of P haemolytica into tissue chambers was accompanied by marked changes in the composition of chamber fluid. Increased total protein and albumin concentrations, decreased pH, and disruption of chamber tissue vasculature were associated with a significant increase in the penetration of sulfadiazine and trimethoprim into infected tissue chambers, compared with that in noninfected chambers. This increased penetration was accompanied by increases in the apparent volume of distribution for sulfadiazine and trimethoprim.
Pharmacokinetics of ceftazidime given alone and in combination with probenecid to unweaned calves
Authors: Soback Stefan , Ziv Gideon
Published: February 2025

Ceftazidime pharmacokinetic values were studied in unweaned calves given the antibiotic alone or in combination with probenecid. Ceftazidime was administered iv to 9 calves at a dosage of 10 mg/kg of body weight and im (10 mg/kg) to 8 calves, to 7 calves (10 mg/kg plus probenecid [40 mg/kg]), and to 9 calves (10 mg/kg plus probenecid [80 mg/kg]). Serum concentration-vs-time data were analyzed, using noncompartmental methods based on statistical moment theory. The data for iv ceftazidime administration also were fitted by use of a linear, open 2-compartment model.

The mean (± sd) terminal half-life was 138.7 ± 23.6 minutes and 126.3 ± 10.5 minutes after iv and im administrations, respectively. The mean residence time was 167.3 ± 21.1 minutes and 201.4 ± 16.8 minutes after iv and im administrations, respectively. Coadministration of probenecid did not affect the terminal half-life or mean residence time values. The total body clearance was 1.75 ± 0.26 ml/min/kg, and the volume of distribution at steady state was 0.294 ± 0.064 L/kg. The estimated mean absorption time was 34.1 minutes.

There were no significant differences between the mean residence time calculated by statistical moment theory or by compartmental analysis, indicating central compartment output of ceftazidime.

The 90% minimal inhibitory concentration values of ceftazidime determined for Escherichia coli, Salmonella spp, Pasteurella multocida, and P haemolytica isolates ranged from < 0.01 to 0.1 μg/ml.
Effect of food deprivation on d-xylose absorption test results in mares
Authors: Freeman David E. , Ferrante Pamela L. , Kronfeld David S. , Chalupa William
Published: February 2025

A d-xylose absorption test was conducted on 4 healthy mares deprived of food for 12, 36, 72, and 96 hours before the test, with a 13- to 15-day adjustment period between each test. Maximal plasma concentrations after 72 and 96 hours of food deprivation were approximately 36% lower than those obtained after the 12- and 36-hour periods (P = 0.0001). Absorption curves were flatter and the decrease in plasma concentration was slower after the 72- and 96-hour periods of food deprivation. The rate of d-xylose absorption (P = 0.0108) and the initial rate of urinary excretion (P = 0.0117) were slower at 72 and 96 hours. Gastric emptying appeared to be progressively delayed with food deprivation, as evident by the delay in peak d-xylose excretion in urine (P = 0.0268). Areas under the plasma concentration-time curves and quantitites of d-xylose excreted in urine were similar for all periods of food deprivation, evidence that the same amounts of d-xylose were absorbed, despite changes in the plasma curve. A 15-hour collection period was sufficient to recover all d-xylose excreted in the urine, and during all periods 9.8 ± 0.6% (mean ± sem) of the oral dose was eliminated in the urine.
Detection of intracellular canine distemper virus antigen in mink inoculated with an attenuated or a virulent strain of canine distemper virus
Authors: Blixenkrone-Møller Merete
Published: February 2025

Using an indirect immunofluorescence technique, the distribution of viral antigen in various tissues and blood mononuclear leukocytes was studied in wild mink, either vaccinated with an attenuated vaccine strain of canine distemper virus (cdv) or experimentally inoculated with the virulent Snyder-Hill strain of cdv. Viral antigen was detected in cells of the lymphoid system 6 to 12 days after vaccination. From 2 to 3 days after inoculation with the virulent strain, cdv antigen was demonstrated in cells of the lymphoid system and, during the incubation period, the antigen had spread to the epithelia and brain at days 6 and 12, respectively. In clinical cases of acute fatal canine distemper, the viral antigen was detected in a wide variety of tissues, including the cells of the lymphoid system, epithelial cells of skin, mucous membranes, lung, kidney, and cells of the cns. The diagnostic importance of cdv antigen detection is discussed on the basis of these findings.
Large intestinal capacity, retention times, and turnover rates of particulate ingesta associated with extensive large-colon resection in horses
Authors: Bertone Alicia L. , VanSoest Peter J. , Johnson Donald , Ralston Sarah L. , Stashak Ted S.
Published: February 2025

Fecal excretion of a particulate marker, ytterbium (Yb), was evaluated in 9 horses before surgery and 3 weeks, 3 months, and 6 months (4 trials) after sham-operation (group 1; n = 3) or extensive large colon resection (group 2; n = 6). Fecal excretion curves of total Yb excretion, loge Yb excretion, % Yb excretion, loge % Yb excretion, and cumulative % Yb excretion were evaluated, and kinetic analysis was performed on the loge Yb excretion curves to detect mixing pools and to calculate the fractional rate of particulate passage, turnover rate, and pool size. Calculations were performed to determined transit time, mean overall retention time, adjusted mean retention time, peak time, and disappearance time. Values were statistically analyzed to determine differences between groups and among trials (P < 0.05).

Group-2 horses had significantly shorter transit, peak, and mean overall retention times, compared with preoperative values and with values for group-1 horses. Two mixing pools were identified: a slower emptying pool of 5.7% hour-1 (k1) and a faster emptying pool of 12.3% hour-1(k2). The rate of passage from the first pool (k1) was not altered by colon resection, and was interpreted as being most influenced by the cecum. In further support of this interpretation, the capacity of the k1 pool approximated the capacity of the cecum (17 L). The capacity of the k1 pool significantly expanded by 6 months in the resected horses. The rate of passage from the second pool (k2) significantly increased initially after colon resection (3 weeks and 3 months), but returned to preoperative values by 6 months. This pool was affected by colon resection, and was therefore interpreted as being influenced by a portion of the colon. Despite these changes in rate of passage and capacity of the mixing pools, on all the trials, colon resection decreased intestinal transit time and overall mean retention time because of a decrease in the total large intestinal length or capacity. This decrease in particulate matter retention and transit time may partially or totally explain the decrease in fiber digestion reported in horses with extensive large colon resection.
Direct effects of Pasteurella haemolytica lipopolysaccharide on bovine pulmonary endothelial cells in vitro
Authors: Paulsen Daniel B. , Mosier Derek A. , Clinkenbeard Kenneth D. , Confer Anthony W.
Published: February 2025

Bovine pulmonary artery cells in cell culture were exposed to lipopolysaccharide (lps) purified from Pasteurella haemolytica serotype Al. This resulted in severe membrane damage, which caused a time- and dose-dependent release of lactate dehydrogenase that was first detected 4 hours after exposure and reached a maximal mean release of 67% after 24 hours of exposure to 1 μg of lps/ml. Mean release of 51chromium followed by a similar pattern and reached a maximum of 61% following 24 hours of exposure to 10 μg of lps/ml. Morphologically, endothelial cells responded to lps by marked cell membrane retraction, the formation of numerous cytoplasmic blebs, and ruffling of the cell membrane. Subsequently, the cells became round and detached. Cell detachment reached a mean of 95% following 8 hours of exposure to 1 μg of lps/ml. These studies demonstrated that P haemolytica lps is capable of causing direct damage to bovine pulmonary arterial endothelial cells, which may be important in the pathogenesis of bovine pneumonic pasteurellosis.
Rapid detection of Streptococcus suis serotype 2 in weaned pigs
Authors: Moreau Alain , Higgins Robert , Bigras-Poulin Michel , Nadeau Marie
Published: February 2025

A survey to detect Streptococcus suis serotype 2 in 1,716 weaned pigs was done in Quebec. Forty-nine sow herds surve included in this survey: in 26 herds, S suis serotype 2 had been isolated during the preceding 12 months and in 23 herds (control), the organism had not been detected during a previous study. Swab specimens of the nasal cavity and tonsils of pigs were obtained for bacteriologic culture, and S suis serotype 2 was easily detected by the use of brain-heart infusion agar containing a Streptococcus-selective supplement and 5% goat antiserum raised against S suis serotype 2. After measurement of the diameter of the precipitation zone of 539 isolates, a slide agglutination test was performed to identify the S suis serotype 2 isolates. The mean precipitation zone diameter obtained for group S suis serotype 2 was larger (P < 0.001) than that for the group designated as “others.” With slide agglutination test results as reference and on the basis of discriminant analysis to simulate detection of S suis serotype 2, 93.1% of all isolates were correctly classified, using the precipitation zone diameter as unique classification criterion. Relative specificity was 94.5% and relative sensitivity was 88.7%.

Use of the precipitation zone diameter on a quantitative basis led to the proposal of a simple and reliable technique to screen swine herds for S suis serotype 2 in weaned pigs. Nasal and tonsillar swab specimens were obtained and analyzed concurrently for S suis serotype 2. The organism was found in both sites in only 20.4% of 103 carrier pigs. Nasal and tonsillar specimens yielded 55.3 and 65%, respectively, of all S suis serotype 2 isolates. Statistically significant difference was not observed between the numbers of S suis serotype 2 isolated from each site. Both sites permitted the recovery of S suis serotype 2 isolates; it was advantageous to use nasal and tonsillar swab specimens to determine the most reliable evaluation of S suis sterotype-2 carrier status in weaned pigs.
Characterization of the plasmids of Moraxella bovis
Authors: Wilt G. R. , Wu G. , Bird R. Curtis
Published: February 2025

Restriction endonuclease digestions were performed on plasmids purified from Moraxella bovis isolates GRS, Newport, and IBH64. It was determined from single and double digestions of plasmid dna that GRS and Newport isolates carried 3 large plasmids having molecular sizes of 43.8, 41.3, and 32.8 kilobases (kb). Digestion of the 3 large plasmids and restriction endonucleases Hae III, HindIII, Nde I, and Ava I strongly indicated that these isolates shared structurally identical large plasmids. Timed single digestions with Ava I revealed that the IBH64 isolate carried 2 large plasmids having molecular sizes of 45 and 32.8 kb. The 32.8-kb plasmid was the only large plasmid that appeared to be shared by all 3 M bovis isolates. Two isolates, Newport and IBH64, carried small plasmids in addition to the large plasmids. Restriction maps were constructed for the 43.8-, 41.3-, and 32.8-kb plasmids.
Changes in articular cartilage after intra-articular injections of methylprednisolone acetate in horses
Authors: Chunekamrai Siraya , Krook Lennart P. , Lust George , Maylin George A.
Published: February 2025

Eight mature horses with no prior signs of joint disease or history of intra-articular therapy were treated with 8 weekly intra-articular injections of methylprednisolone acetate. Treatments were given at a dose of 120 mg/joint into the right radiocarpal and intercarpal joints, with the left joints as untreated controls. Articular cartilage samples were obtained at necropsy 1, 4, and 8 weeks after the last injection.

Compared with controls, cartilage from injected joints had a loss of hematoxylin basophilia and decreased intensity of staining in safranin O fast green dye. Chondrocyte necrosis and hypocellularity were observed in all sample of cartilage from treated joints. Proteoglycan content and its rate of synthesis were reduced. There was a progressive loss of proteoglycan content, whereas proteoglycan synthesis increased somewhat 4 and 8 weeks after treatment. Collagen content was unchanged, but its rate of synthesis was markedly inhibited. Collagen synthesis did not recover, but remained decreased at 5 to 15% of the values from untreated cartilage. Water percentage was increased, but fibronectin content was not significantly different.

A single injection of methylprednisolone acetate was also given into the right metacarpophalangeal joints of 3 of the 8 horses in this group, with the left joints serving as untreated controls. Sixteen weeks after the treatment, cartilage of the treated joints had a loss of histochemical staining and proteoglycan content was reduced to 50% of control values. The mean rate of proteoglycan synthesis and mean fibronectin content were increased, but the differences were not statistically significant (P > 0.05). Other variables were essentially unchanged. For control studies, the right carpal joints of 2 additional horses were injected with the drug suspension vehicle. All measurements, compared with those of samples from untreated joints, were unchanged.

On the basis of our findings, we concluded that the effects on cartilage of intraarticular injections of methylprednisolone acetate were not ameliorated at 8 weeks after 8 weekly injections or 16 weeks after a single injection. Cartilage remained biochemically and metabolically impaired.
Evaluation of canine mast cell tumors for presence of estrogen receptors
Authors: Larsen Arden E. , Grier Ronald L.
Published: February 2025

Ten tumors from 7 dogs were analyzed for estrogen receptors. Of 9 determined to be mast cell tumors, 6 were determined not to have estrogen receptors (< 3 fmol of estradiol/mg of cytosol protein) and 3 were questionable (3 to 10 fmol of estradiol/mg). One tumor was a mixed mammary tumor and was determined to have estrogen receptors (12 fmol of estradiol/mg). Histologic grading of the mast cell tumors did not suggest a correlation with estrogen receptor values.
Virus-specific cellular blastogenesis and interleukin-2 production in swine after recovery from African swine fever
Authors: Scholl Thomas , Lunney Joan K. , Mebus Charles A. , Duffy Ellen , Martins Carlos L. V.
Published: February 2025

Animals recovered from viral diseases represent an important model to study the host cellular and humoral immune responses to the etiologic agents. This is particularly important for African swine fever virus (asfv) infections in which antibodies have little or no virus-neutralizing effect. Pigs surviving experimental infection with the naturally occurring low-virulent, nonhemadsorbing asfv/NH/P68 (NHV) isolate did, however, exhibit virus-specific T-cell activities, as measured by a variety of assays. A strong virus-induced, antigen-specific blastogenic response was observed only with blood mononuclear cells (bmc) from asf-recovered swine, whereas cells from recovered and naive swine responded similarly to the mitogens concanavalin A and phytohemagglutinin. The asfv-induced blastogenesis was dependent on virus dose and on the presence of adherent cells. Blood mononuclear cells cultured with antigenically related hemadsorbing asfv isolates of different virulence characteristics, the highly virulent L60 isolate and moderately virulent DRII isolate, exhibited a similar magnitude of blastogenesis to cells infected with the low-virulent NHV isolate. Virus-infected cells proved to be an efficient inducer of interleukin-2 (il-2) activity to cells from recovered swine, but not from naive swine, whereas T-cell-specific lectins induced production of similar amounts of il-2 activity from cells of naive and recovered swine. Correlated with the appearance of virus-induced il-2 activity in the culture supernatant was the induction of promiscuous killing in cells exposed to prolonged (7 days) virus stimulation. This lymphokine-activated killing could be induced experimentally early in the virus stimulatory process (3 days) by the addition of exogenous lymphokines to the cultures. It was concluded that swine inoculated with low-virulent asfv isolates are a useful model for identifying and characterizing asfv immune mechanisms in vitro. Furthermore, this asfv model implicates lymphokines as inducers of nonspecific cell-mediated immunity; in fact, lymphokine-activated killer type responses may contribute to recovery from this viral infection. More important, asfv-specific blastogenic and cytotoxic T-cells are prime candidates for the cells inducing and/or conferring protective immunity against challenge asfv infection.
Isolation and characterization of equine microvascular endothelial cells in vitro
Authors: Bochsler Philip N. , Slauson David O. , Chandler Suzanne K. , Suyemoto M. Mitsu
Published: February 2025

The use of cultured tissue has not yet become widespread in research involving equine disease, and this may be attributable in part to the scarcity of published reports concerning tissue culture methods for this species. We report here the isolation of equine microvascular endothelium (emve) from fresh omental tissue of horses and ponies. Fresh donor tissue was minced, subjected to collagenase digestion, and filtered. Cells were layered on 5% bovine serum albumin for gravity sedimentation, the bottom layer was collected, and the cells were plated onto fibronectin-coated flasks. Medium consisted of Dulbecco modified Eagle medium with 10% whole fetal bovine serum (wfbs) and 20 μg of endothelial cell growth supplement/ml. The emve grew readily in culture, had the cobblestone morphologic feature at confluence, stained positively for factor VIII-related antigen, and metabolized acetylated low-density lipoprotein. Fibroblast and smooth muscle cell contamination was minimal in primary cell cultures, which were successfully passed and maintained in culture for 3 to 5 serial passages, using various media and substrates. Preliminary studies were undertaken to determine optimal growth conditions with a range of variables: serum concentration, extracellular matrix components, and growth factors, Optimal conditions were achieved with a minimum of 10% wfbs, and with either fibronectin or laminin as extracellular matrix substrates. The emve grew adequately in Dulbecco modified Eagle medium plus 10% wfbs, and the added growth factors or serum supplements did not appear necessary for growth of emve.
Evaluation of humoral immunity to Brucella sp in cattle by use of an agar-gel immunodiffusion test containing a polysaccharide antigen
Authors: Lord Veronica R. , Rolo Morelia R. , Cherwonogrodzky John W.
Published: February 2025

Results of a double agar gel immunodiffusion (Ouchterlony) test that contained a polysaccharide (poly-B) antigen of Brucella melitensis strain B115 were compared with those of 5 other serotests. To determine the sensitivity and specificity of the immunodiffusion, standard tube, 2-mercaptoethanol, Rivanol, card, and complement fixation tests, sera obtained from 1,328 vaccinated, infected, and seronegative cattle, 56 of which had been examined bacteriologically, were used to evaluate the humoral response to Brucella sp. The poly-B antigen confirmed infection in 87.5% of the 56 cattle from which Brucella abortus biotype 1 had been isolated, and in 96.6% (205/212) of a group of cattle suspected to be infected on the basis of results of conventional serotests. Likewise, sera from 4 groups of vaccinated cattle did not react with poly-B antigen, whereas they did react in conventional tests. The poly-B antigen was more specific in detecting infected cattle even in a group of vaccinated adults. A useful strategy to identify infected cattle might be screening, using a combination of the Rivanol and card tests together with the agar-gel immunodiffusion test containing poly-B antigen.
Acute response of urine pH following ammonium chloride administration to dogs
Authors: Shaw Darcy H.
Published: February 2025

To test the acidifying ability of the distal portion of the nephrons in healthy dogs, 0.2 g of NH4Cl/kg of body weight was given PO. Samples for venous blood gas analysis and urine pH were taken hourly for 6 hours. Systemic acidemia developed, as evidenced by a statistically significant (P < 0.05) decrease in blood pH 1 hour after NH4C1 administration. Four hours after administration, mean urine pH decreased to a low of 5.16 ± 0.1 and was < 5.5 3 hours after administration. Changes in urine pH 2 hours after administration were statistically significant (P < 0.05). In human beings, NH4C1 loading is used to detect patients with distal renal tubular acidosis (defective hydrogen ion secretion by the distal nephrons) and normal acid/base values. Distal renal tubular acidosis is diagnosed if urine pH fails to decrease to < 5.5 after NH4C1 administration. On the basis of the findings of this study, a similar value would be valid for dogs.
Effects of lipoxygenase inhibitors in a model of lens-induced uveitis in dogs
Authors: Dziezyc Joan , Millichamp Nicholas J. , Rohde Brooks H. , Baker Joshua S. , Chiou George C. Y.
Published: February 2025

Uveitis was induced in dogs by intracameral injection of canine lens protein. The lipoxygenase inhibitors phenidone and norhydroguaiaretic acid, and dimethyl sulfoxide decreased fibrin production at 0.5 and 1 hour after induction of uveitis. Phenidone and norhydroguaiaretic acid also inhibited the initial increase in intraocular pressure early in the course of inflammation. Leukotriene B4 in the aqueous was measured by inflamation use of radioimmunoassay at 1 hour after inflammation. In control dogs, 230 to 1,700 pg of leukotriene B4/ml was measured; in dogs treated with phenidone, leukotriene B4 was not measured.
Role of parathyroid hormone in the anemia of chronic terminal renal dysfunction in dogs
Authors: Petrites-Murphy M. B. , Pierce Kenneth R. , Lowry Stephen R. , Fisher James W.
Published: February 2025

Terminal renal dysfunction (trd) was induced in 2 groups of dogs by partial surgical ablation of the kidney. Dogs of a control group and of 1 of the trd groups were maintained on a diet containing normal phosphorus concentration, whereas dogs of the other trd group were maintained on a low-phosphorus diet. Mild anemia developed in dogs of both trd groups and could not be attributed to iron deficiency, increased erthrocyte concentration of 2,3-diphosphoglycerate, or absolute deficiency of erythropoietin (ep).

Subsequently, all dogs were acutely depleted of approximately 25% of their blood volume. Erythropoietin concentration in dogs of the trd groups was lower than that of controls, however, erythroid regenerative capacity was comparable with that of control dogs when plasma parathyroid hormone (pth) concentration was lowered by reduced dietary intake of phosphorus.

The PCV in dogs of the chronic trd groups had a slight positive correlation with serum ep concentration, and a significant (P < 0.05) negative correlation with plasma pth and serum phosphorus and creatinine concentrations, using a correlation matrix. There was no longer a significant correlation between plasma pth concentration and PCV after controlling for serum creatinine concentration by use of a multiple linear regression analysis. A significant (P < 0.05) negative correlation also was observed between plasma pth and serum ep concentrations, but not between serum ep and phosphorus or creatinine concentrations. Significance of the ep and pth association was reduced when analyzed, using a multiple linear regression analysis that included serum creatinine values. According to these data, pth does have an independent effect on ep concentration, but the relationship between pth and ep is not sufficiently strong to account for the genesis of the anemia of chronic trd.
Aortic catheterization in cattle via the costoabdominal artery and validation for progesterone and estradiol-17β sample collection
Authors: Haibel George K. , Guilbault Louis A. , Villeneuve Paul , Thatcher William W.
Published: February 2025

The abdominal portion of the aorta was catherized in 27 cows. Local analgesia was achieved by infiltration of anesthetic agents. A 10-cm skin incision was made caudal and parallel to the 13th rib at the lateral border of the epaxial muscles. The dorsal costoabdominal arteiy was exposed at its first lateral cutaneous branch by careful dissection through fascial layers. A sterile polyvinyl catheter (1.52 mm od) was inserted into the artery and was advanced 35 to 40 cm to the abdominal portion of the aorta. Catheter patency was maintained for up to 5 weeks. Concentrations of plasma progesterone and estradiol-170 in samples obtained from the abdominal portion of the aorta were similar to simultaneously obtained concentrations in samples from the jugular vein before and after parturition.
Prevalence of bovid herpesvirus-4 and its antibody in cattle in Minnesota
Authors: Naeem Khalid , Goyal Sagar M. , Werdin Ronald E.
Published: February 2025

Serologic analyses and virus isolation studies were carried out to determine the role of bovid herpesvirus-4 (bhv- 4) in infections in cattle, principally those of the reproductive tract. Serologic analyses were performed, using an indirect fluorescent antibody test on thoracic fluid specimens from aborted fetuses and on sera from 3 sources of adult cattle. Virus isolation was attempted from field cases of abortion, early embryo death, and postpartum vulvovaginitis/metritis, using uterine discharge and buffy coat preparations obtained from cows and tissues obtained from aborted fetuses. Of 420 fetal thoracic fluid specimens examined, 5 were positive for bhv-4 antibodies. Seventeen percent of adult cattle from 2 sources ie, clinically normal herds and abattoir cattle, were seropositive for bhv-4 antibodies. Cattle from a third source, 4 herds with high incidence of reproductive tract disorders, had a seroprevalence rate between 36 and 88%. Two isolates of bhv-4 were also obtained from this group. The overall incidence of bhv-4 antibodies in clinically normal cattle was higher than previously recognized, with relatively higher prevalence in herds having reproductive problems (x2 = 156.5, P < 0.005). At least 10% of the bhv-4 antibody-positive sera did not have neutralizing antibody against bovine viral diarrhea virus and/or bovid herpesvirus-1, both important causes of bovine reproductive tract disorders.