bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental inoculation of cattle with bovine herpesvirus-4: Evidence for a lymphoid-associated persistent infection
Authors: Osorio Fernando A. , Reed David E.
Published: February 2025

A strain of bovine herpesvirus-4 isolated from cows with mammary pustular dermatitis was used for experimental inoculation of cattle. This strain is serologically indistinguishable from the group prototype Movar 33/63 and from strain DN-599. Seronegative cattle were inoculated iv or by simultaneous intranasal, iv, intramammary (via teat channel), and intradermal inoculations. All inoculated cattle seroconverted. Clinical signs of disease or lesions were not evident, except for a dermal lesion corresponding with one intradermal inoculation site. Virus was recovered from the dermal lesion and was excreted in the milk for 17 days. Virus was recovered from esophagopharyngeal fluid at 9 and 13 days after inoculation. At different times of euthanasia (2 to 14 months after inoculation), virus was recovered from cocultures with bovine lung cells and/or explant cultures of lymph nodes, spleen, tonsils, and, in one case, kidney. In 2 animals, the virus was recovered repeatedly during 1 year from peripheral blood leukocytes by cocultivation with bovine lung cells. The number of infectious leukocytes, as determined by infectious center assay, ranged from < 1 to 6 infectious celis/107 leukocytes.
Characterization of deoxyribonucleic acid from cells infected with Aleutian disease virus
Authors: Hahn Edwin C. , Ramos Luciano , Kenyon Alan J.
Published: February 2025

Viral DNA was extracted from Crandell feline kidney (crfk) cells infected with Aleutian disease virus (adv) and labeled with [3H]thymidine. The sedimentation coefficient in alkaline sucrose gradients was 16S corresponding to a molecular weight of 1.5 × 106. The buoyant densities of DNA from infected and control cells were determined by isopyknic sedimentation in CsCl and NaI gradients. Two additional peaks of [3H]DNA were found in infected cells, but not in control cell extracts. Fractionation of this DNA on hydroxylapatite indicated that the new peaks represented a single-stranded component, density 1.728 g/cm3, and a double-stranded component, presumed to be a viral replicative intermediate, density 1.718 g/cm3. The target antigen formation in crfk cells was measured by γ-irradiation of adv and assayed for focus formation. The calculated size of adv based on these measurements was 1.1 × 106. The H-1 parvovirus also was shown to have a size of 1.5 × 106 daltons for both antigen and plaque formation. The data indicated similarities existed between adv and other autonomously replicating parvoviruses in most properties, except that less-than-unit length genome of adv may be transcribed.
Effects of extensive resection of the small intestine in the pony
Authors: Tate Lloyd P. , Ralston Sarah L. , Koch Christine M. , Everitt Jeffrey I.
Published: February 2025

Small intestinal resection (sir) is not uncommonly done in surgical treatment of equine colic, but little is known about the long-term effects of sir on horses and ponies. Twelve ponies, fed maintenance amounts of pelleted feed, were divided randomly into 4 treatment groups. d-Xylose absorption curves were recorded for each pony before surgical treatments were performed. Treatments consisted of control (ileal bypass) and 40%, 60%, or 80% sir. d-Xylose absorption, serum electrolyte, and enzyme profiles for each animal were recorded once every 30 days for 180 days after surgical treatment, and the ponies were weighed every 2 weeks. The ponies then were necropsied and the remaining small and large intestine were examined.

d-Xylose absorption values were depressed (P < 0.05) in the ponies subjected to 40%, 60%, and 80% sir as compared with the absorption values of the controls. The ponies with the 60% and 80% sir lost body weight throughout the experimental period, whereas the controls and the ponies with 40% sir maintained their base-line (presurgical manipulation) weight. Serum alkaline phosphatase activity was increased (P < 0.05) in the ponies subjected to 60% and 80% sir and significant biliary hyperplasia was present in those with 80% sir. Extensive (≥ 60%) sir severely compromised the capability of ponies to absorb nutrients and to derive adequate nutrition from a maintenance diet, resulting in changes in hepatic parenchyma and elevations in serum alkaline phosphatase. These changes are consistent with those reported in other species following sir.
Pharmacokinetics of oxytetracycline in young cattle: Comparison of conventional vs long-acting formulations
Authors: Toutain P. L. , Raynaud J. P.
Published: February 2025

Pharmacokinetics of a long-acting formulation of oxytetracycline (otc) was studied in young cattie after iv and im injections (20 mg/kg of body weight), Oxytetracycline tissue concentrations were also determined after im injection. Comparisons with the conventional formulation of otc (using different administration schedules) were made, using the same total dosage after assessing serum otc concentrations, areas under the curve, and peripheral drug quantities.

The im administration of the long-acting formulation was followed by a rapid (60 to 90-minute) achievement of maximal serum concentrations (4 μg/ml) which then persisted for an additional 12 hours. Thereafter, serum concentrations decreased, and a half-life of 21.83 hours was calculated, the length of which was attributed to a combination of continued absorption and elimination. A bioavailability of 51.5% was determined. Two rates of absorption of the drug from the im site of administration were indicated. From analogic simulation, it was apparent that 14% of the dose was rapidly absorbed with a halflife of absorption of 48 minutes. The remaining 37.5% was absorbed more slowly with a half-life of 18.1 hours.

Drug concentrations in the tissues decreased exponentially with time. Lung concentrations closely approximated serum values and were maintained at > 0.5 μg/ml for approximately 65 hours. Higher and more persistent values were found in the kidney and liver tissue.

The long-acting formulation after single im administration produced higher quantities in the peripheral compartment in comparison with that after daily administration of the conventional formulation, using 2 dosage schedules, as determined by analogic computation. The present findings indicated that the long-acting formulation was an effective way to administer otc and removed the need for repeated daily treatments.
Pharmacokinetics of gentamicin in birds of prey
Authors: Bird J. E. , Miller K. W. , Larson A. A. , Duke G. E.
Published: February 2025

The pharmacokinetics of gentamicin, including half-life, apparent volume of distribution, total body clearance, and fraction of drug absorbed from im injection sites, were determined in 3 species of birds of prey (red-tailed hawks, great horned owls, and golden eagles). Significant differences (P < 0.05) between species were found for the half-life and total body clearance values for this broadspectrum antibiotic. The values for apparent volume of distribution and fraction absorbed did not differ among species and were similar to those reported in mammals. Rapid and relatively complete absorption from im injection sites resulted in high bioavailability. After TV administration of 10 mg of gentamicin/kg of body weight, serum concentrations > 12 μg/ml were present for at least 2 hours and > 2 μg/ml for 4 to 6 hours. On the basis of the various determinations, an im dose of 2.5 mg of gentamicm/kg given every 8 hours should provide therapeutic serum concentrations of gentamicin in the 3 species.
Degenerative joint disease: Multiple joint involvement in young and mature dogs
Authors: Olsewski John M. , Lust George , Rendano Victor T. , Summers Brian A.
Published: February 2025

Radiologic, pathologic, and ancillary methods were used to determine the occurrence of degenerative joint disease involving multiple joints of immature and adult dogs. Animals were selected for the development of hip joint dysplasia and chronic degenerative joint disease. Of diseaseprone dogs, 82% (45 of 55 dogs) had radiologic changes, indicative of hip dysplasia, by 1 year of age. At necropsy, more abnormal joints were identified than by radiographic examination. Among 92 dogs between 3 to 11 months of age that had joint abnormalities, 71% had hip joint involvement; 38%, shoulder joint involvement; 22%, stifle joint involvement; and 40% had multiple joint involvement. Polyarthritis was asymptomatic and unexpected. Radiographic examination of older dogs also revealed evidence of degenerative joint disease in many joints. Multiple joint involvement was substantiated at necropsy of young and mature dogs.

A similar pattern of polyarticular osteoarthritis was revealed in a survey (computer search) of necropsy reports from medical case records of 100 adult and elderly dogs. Usually, the joint disease was an incidental observation, unrelated to the clinical disease or to the cause of death.

The frequent occurrence of degenerative changes in several joints of dogs aged 6 months to 17 years indicated that osteoarthritis may be progressive in these joints and raises the possibility that systemic factors are involved in the disease process.
Effect of an endophytic fungus isolated from toxic pasture grass on serum prolactin concentrations in the lactating cow
Authors: Wallner Barbara M. , Booth Nicholas H. , Robbins Joe D. , Bacon Charles W. , Porter James K. , Kiser Terry E. , Wilson Ruel , Johnson Bennett
Published: February 2025

Serum prolactin (prl) concentrations were determined (by radioimmunoassay) in lactating Holstein cows orally dosed for 3 consecutive days with cultures of Balansia epichloë, an endophytic fungus of pasture grasses. Two control groups (2 animals/group) were given either saline solution or noninoculated culture medium, and the principal or 3rd group of 2 animals were given cultures of B epichloë. Serial samples of venous blood were collected (via jugular cannula) from the cows before and after injection (iv) of thyrotropin-releasing hormone (trh).

Serum prl concentrations were increased (P < 0.05) in the control cows (both groups) after they were treated with trh, but not in the principals (given fungal cultures). Milk production recorded before and after dosing the cows with saline solution, noninoculated culture media, or fungal cultures was not affected by any of these oral dosings.

In a 2nd study, a control group and a principal group (3 Holstein cows each) were orally dosed for 3 consecutive days with noninoculated culture medium and with B epichloë culture, respectively. The cows were given an iv dose of trh, as described. In addition, serial samples of venous blood were collected before and after morning and evening milkings. Milk production was recorded before and after dosing the animals with noninoculated culture media or B epichloë culture. Serum prl concentrations were lower (P < 0.05) in the principal cows (given B epichloë culture) than in control cows after trh administration. In addition, B epichloë decreased the milking-induced increase in serum prl concentration. Milk production was not affected by oral dosing with noninoculated media or fungal culture.

This study is the first to indicate that B epichloë or its metabolites significantly depressed hypophyseal release of prl and that milk production was not affected when lactating cows were dosed with this fungus on a short-term treatment basis.
Detection of ovulation in goats by blood prostaglandins concentrations
Authors: Akinlosotu B. A. , Verma O. P.
Published: February 2025

Eighteen mature female goats of nondescript breed were randomly assigned equally to 3 treatment groups. Group I goats served as controls, group II goats were treated (iv) with a single dose of 300 μg of synthetic luteinizing hormone-releasing hormone (lhrh); group III goats were treated with lhrh (similar to group II) and 24 hours later were given indomethacin (10 mg/kg; im) which dosing was repeated every 6 hours for the next 90 hours. Blood samples were collected from all animals every 6 hours until 120 hours and assayed for prostaglandin E (pge) and pgf2α.

On days 7 and 8, the animals were surgically laparotomized to observe the ovarian activity. In groups I and III goats, there was no evidence of follicular development or ovulation, but in 4 of the 6 group II goats, there were ovulatory points or corpus luteum. Mean plasma pge and pgf2α concentrations in control goats did not vary significantly (P ≤ 0.05) during the sampling period; but in the lhrh-treated goats (group II), these concentrations peaked twice— a low peak at 24 hours and a sharp peak at 78 to 90 hours. In contrast, these concentrations in group III goats (lhrh plus indomethacin) dropped sharply in the control group (I) value after reaching the 1st peak, and then stayed at this low plateau for the remainder of the sampling period; the 2nd peak was absent.

The results indicate that the ovulation could be induced by lhrh injection in anestrus goats and that ovulation is preceded by a marked increase of plasma pge and pgf2α concentrations.
Cardiovascular and neuromuscular effects of pancuronium bromide in the pony
Authors: Manley S. V. , Steffey E. P. , Howitt G. A. , Woliner M.
Published: February 2025

Dosage level requirements of pancuronium bromide, a nondepoiarizing muscle relaxant, were studied in ponies. Cardiovascular and neuromuscular responses, duration of responses, and undesirable effects such as prolonged paralysis or residual weakness in recovery were also evaluated. Neuromuscular responses to supramaximal nerve stimulus of the superficial peroneal nerve were recorded as twitch height on a physiograph. Cumulative pancuronium dosage level required to reduce evoked twitch height to 90% to 99% of base-line height was 0.125 ± 0.017 mg/kg of body weight. Time to recovery of 50% of base-line evoked twitch tension was 16 ± 6 minutes. Recovery to base-line tension required 24 ± 10 minutes. Repeat dosage requirements to again achieve 90% to 99% twitch height reduction was 0.04 ± 0.01 mg/kg. Duration to 50% of recovery from a repeated dose was 20 ± 9 minutes, and to 100% of base line was 28 ± 9 min. Prolongation of the 2nd dose was significant (P < 0.05).

A slightly significant (P < 0.05) increase in systolic blood pressure and heart rate persisted. Dysrhythmias were not noticed. Facial muscle twitch response subjectively persisted at base-line strength, despite maximum hindlimb relaxation. Facial muscle twitch did not fade in response to tetanic stimulus. Recovery from anesthetic was not weak or prolonged, and immediate or delayed neuromuscular problems were not noticed.
Cytologic observations of the bovine teat end
Authors: Nickerson Stephen C. , Pankey J. W.
Published: February 2025

Cells infiltrating from the vasculature and histologic components of internal tissues of teats (mammary papilla) from noninfected udder quarters were studied, using light and electron microscopy. Morphometric analysis demonstrated a progressive increase in number of infiltrating cells from the distal teat cistern (sinus papillaris) to the junction of the Furstenberg's rosette (distal termination and convergence of mucosal folds lining the teat cistern) and the streak canal (ductus papillaris). Plasma cells contributed to cellular increases in subepithelial connective tissue and were the most prevalent infiltrating cell type. Plasma cells also penetrated the basal epithelial lining of the rosette area and occasionally migrated to the luminal surface near the squamocolumnar junction. Neutrophils and monocytes contributed to the increase in cells infiltrating the epithelial lining. Few infiltrating cells were observed in epithelium and underlying stroma of the streak canal.

Cytologic comparison demonstrated a reduction in all cell types from lactating to involuting phases of lactation. Greater numbers of plasma cells, lymphocytes, and monocytes were observed in teat end tissues from quarters previously infected with Staphylococcus aureus.
Subcellular biochemical studies of a naturally occurring enteropathy in the dog resembling chronic tropical sprue in human beings
Authors: Batt R. M. , Bush B. M. , Peters T. J.
Published: February 2025

Subcellular biochemical features of a naturally occurring enteropathy in the dog resembling chronic tropical sprue in human beings were examined. Affected dogs had reduced xylose absorption and low concentrations of serum folate, rbc folate, and serum vitamin B12. Histologic examination of peroral jejunal biopsy specimens revealed villous atrophy and a variable infiltration of lymphocytes and plasma cells in the lamina propria. Biochemical assessment of the principal subcellular organelles was achieved by the assay of specific marker enzymes in homogenized jejunal biopsy specimens and in the gradient fractions after isopyknic centrifugation on continuous sucrose-density gradients.

Activities of brush-border marker enzymes were reduced. However, there was no change in the equilibrium density of this organelle, indicating that these quantitative brush-border changes were not accompanied by an alteration in the composition of the microvillous membrane.

Activities of lysosomal enzymes were increased, and there was evidence of enhanced lysosomal fragility and a proliferation of the endoplasmic reticulum. These findings were consistent with an impairment of the functional capacity of the small intestinal mucosa and implicated lysosomes and the endoplasmic reticulum in the disease process.
Hemodynamics during experimental gastric dilatation-volvulus in dogs
Authors: Orton E. Christopher , Muir William W.
Published: February 2025

Gastric dilatation-volvulus (at 30 mm of Hg of gastric pressure) was experimentally induced in 8 dogs under sodium pentobarbital anesthesia. Hemodynamic indices including cardiac output, mean aortic pressure, left ventricular end diastolic pressure, heart rate, total peripheral resistance, and dp/dtmax were measured during a 180-minute period of gastric dilatation-volvulus and for 120 minutes after gastric decompression.

Experimental gastric dilatation-volvulus resulted in significant (P < 0.05) decreases in cardiac output (64%), mean aortic pressure (48%), left ventricular end diastolic pressure (68%), and ventricular dp/dtmax (32%) compared to 4 control dogs. Hemodynamic indices returned toward control values after gastric decompression.

It was concluded that gastric dilatation-volvulus in the present experiment was capable of inducing hemodynamic alterations of a magnitude similar to those reported in gastric dilatation studies, using higher gastric pressures.
Composition of sweat of the horse during prolonged epinephrine (adrenaline) infusion, heat exposure, and exercise
Authors: Kerr M. G. , Snow D. H.
Published: February 2025

Temporal changes in sweat composition were studied in 4 horses during epinephrine (adrenaline) infusion (0.13 to 0.31 μg/kg/min for 3 hours), heat exposure (41 C, [33 C wet bulb] for 5 to 6 hours), and exercise (16 to 18 km/hr for 58 to 80 km). Four ponies also were studied during heat exposure.

Sweat produced by each of the stimuli was hypertonic for Na+, K+, and Cl-. These electrolyte concentrations remained constant during the central period of the experiments, with changes occurring near the beginning and toward the end. The Na+ was significantly higher and K+ significantly lower in epinephrine-induced sweat than in heat-induced sweat, and the pattern of change in sweat Na/K ratio varied among the 3 stimuli. The Ca2+ concentration decreased with time and was hypotonic after 15 minutes of epinephrine-induced sweating.

Concentrations of Mg2+ and protein decreased exponentially with time. There was a high correlation between them, although the Mg2+ was not protein-bound. Sweat urea concentration was directly related to plasma urea concentration. When plasma glucose concentration became greater than 10 to 12 mmole/L during epinephrine infusion, glucose appeared in the sweat and its concentration rose to 8 to 12 mmole/L of sweat when plasma glucose was more than 20 mmole/L.
Zinc concentrations in skimmed milk and whole milk samples from healthy and mastitic cows
Authors: Verheijden J. H. M. , Schotman A. J. H. , van Miert A. S. J. P. A. M. , van Duin C. Th. M.
Published: February 2025

Zinc concentrations were determined in skimmed milk and whole milk samples from healthy and mastitic cows. During spontaneous and induced mastitis, a marked decrease of Zn concentration in skimmed milk from the mastitic quarters was observed. Seemingly, there are 2 mechanisms involved in the lowering of Zn concentration in skimmed milk from mastitic quarters: a decline in Zn probably as a consequence of decreases in plasma Zn concentrations and an abrupt redistribution of Zn in the inflamed quarters.
Gross and light microscopic lesions in neonatal gnotobiotic dogs inoculated with a canine rotavirus
Authors: Johnson Charles A. , Snider Theron G. , Fulton Robert W. , Cho Dooyoun
Published: February 2025

Gross, light microscopic, and morphometric changes were observed in the small intestines of 11 neonatal gnotobiotic dogs after oral inoculation with a canine rotavirus. Starting in pups killed at postinoculation hour (pih) 24, gross changes consisted of moderate dilatation and thinning of the walls of the small intestine, hyperemia, and a moderate amount of semiliquid-to-liquid greenish-yellow intestinal contents. In the jejunum and ileum of inoculated pups killed from pih 18 to 48, columnar villus epithelial cells on the upper one-third of the villus were necrotic, and foci denude of epithelium were seen on the upper regions of villi.

Inoculated pups killed from pih 24 to 72 had mild-to-moderate villus atrophy in the jejunum and ileum, villi covered with cuboidal-to-flat squamous-like epithelial cells, and absence of large, clear vacuoles in the jejunal and ileal villus epithelial cells similar to those seen in villus epithelial cells of 9 control pups. Microscopic sections of the jejunum and ileum from inoculated pups killed from pih 72 to 154 showed slight-to-moderate villus atrophy, and the villi were covered with cuboidal-to-low columnar epithelial cells.

Morphometric results indicated lower mean villus-crypt ratios in the duodenum jejunum, and ileum of inoculated pups. In addition, the morphometry of the small intestine indicated that crypt cell hyperplasia occurred in the duodenum early during infection without obvious villus atrophy, and hyperplasia of the crypt cells in the jejunum and ileum was observed later during the infection.
Effect of age on anion gap in clinically normal Quarter Horses
Authors: Gossett Kent A. , French Dennis D.
Published: February 2025

Anion gap [ag = (Na + K) - (Cl + HCO3)] was determined in Quarter Horses: 10 clinically normal foals 0.5 to 3 days, 2 to 3 weeks, and 5 to 7 weeks of age; 10 yearlings; and ten 2-year-olds. Mean ag (± 1 sd) were 12.8 ± 3.3, 15.2 ± 2.9, 14.0 ± 1.6, 12.3 ± 1.8, and 10.4 ± 1.2 mEq/L, respectively.

The 4 to 5 mEq/L higher ag in 2- to 7-week-old foals, when compared with that in 2-year-old horses, can be explained in part by hyperphosphatemia (2 mEq/L) and lower calcium values (0.4 mEq/L). Decreased globulin concentrations may also contribute to the higher ag.

The ag can be useful in the diagnosis and prognosis of metabolic imbalances in the horse. The age of the animal was important in the interpretation of ag. Age adjustment of reference intervals will increase the usefulness of ag in foals.
Fate of aflatoxins in tissues, fluids, and excrements from cows dosed orally with aflatoxin B1
Authors: Stubblefield R. D. , Pier A. C. , Richard J. L. , Shotwell O. L.
Published: February 2025

A study was conducted to determine aflatoxins in tissues and nontissues of 2 Holstein cows given oral doses of 0.35 mg of purified aflatoxin B1/kg of body weight/day for 3 consecutive days. Cow 1 was slaughtered 24 hours after the 3rd dose, and cow 2, after day 3, was fed aflatoxin-free rations for 7 additional days before slaughter. Tissue samples of brain, gallbladder and bile, heart, intestine, kidney, liver, lung, mammary gland, skeletal muscle, spleen, supramammary lymph nodes, thymus, and tongue, and nontissue samples of blood, feces, milk, rumen content, and urine were examined.

Aflatoxins B1 and M1 were found in all samples of cow 1, except the thymus. Kidney, liver, and mammary gland had the highest concentrations of total aflatoxins (57.9, 13.2, and 25.1 ng/g, respectively), with the aflatoxin M1 concentration 40 times more than the aflatoxin B1 level in kidney. Aflatoxin residues were present (0.02 to 0.11 ng/g) only in kidney, liver, and intestine of the tissues from cow 2 (fed aflatoxin-free feed for 7 additional days). Aflatoxin B1 was not present in nontissue samples, but aflatoxin M1 (0.10 and 1.5 ng/ml) was found in the last milk and urine samples from the same cow. Urine assays are a possible way to monitor the presence of aflatoxin residues in meat tissues.
Bluetongue virus serotype 20 infections in cattle of breeding age
Authors: Groocock C. M. , Parsonson I. M. , Campbell C. H.
Published: February 2025

Ten cattle (6 heifers and 4 bulls) were inoculated with bluetongue virus (btv) type 20. Clinical signs, antibody responses, and capabilities of these animals to replicate and maintain virus were assessed. The cattle showed no clinical signs of disease, although they did develop antibodies to btv which showed long-term increasing titers. Virus was intermittently isolated from samples of blood, but not beyond day 21. Virus was not detected in the semen of the bulls, nor isolated from the tissues of the cattle at necropsy except from the genital tract of the 2 bulls which had been killed within 30 days after their inoculation. Gross and microscopic pathologic changes were not seen in any tissues that were attributable to btv infection. There was no evidence of damage to the reproductive organs or of the development of a latent carrier state in either the heifers or the bulls.
Genetic relatedness of Haemophilus somnus to select genera of bacteria
Authors: Gonzales Herbert F. , Bingham Douglas P.
Published: February 2025

The degree of DNA homology from Haemophilus somnus and DNA from select members of the genera Haemophilus, Actinobacillus, Pasteurella, Escherichia, and Micrococcus was determined. Hybridization tests indicated that H somnus DNA has a 46%, 58%, and 43% homology with the DNA from H influenzae, H parainfluenzae, and A lignieresii, respectively. These percentages of homology values indicate that H somnus was moderately related to 2 members of the genus Haemophilus and 1 member of the genus Actinobacillus. Haemophilus somnus DNA did not show any hybridization with DNA from the genera of Escherichia, Micrococcus, or Pasteurella.
Research needs and priorities for ruminant internal parasites in the United States
Authors: _ _
Published: February 2025

The management-chemotherapy approach is currently the most applicable means of effectively and practically controlling parasites of ruminants. Knowledge of regional patterns for major ruminant parasites, especially seasonal transmission dynamics, promises to lead to major improvements in management-chemotherapy systems. This knowledge also provides the fundamental context for design of new integrated control strategies that include other approaches such as immunization, chemical and biological control, and the interaction of environmental, physiologic, and nutritional factors. Greatly needed is a change in the protracted government regulatory process that obviates the availability of new, more effective drugs until years after they are available in other developed nations and that creates a dearth of “minor species, minor use” antiparasitic compounds. It is necessary to recognize both the need for product safety and the realities of investment limitations in the pharmaceutical industry. Also needed are new formulations and better methods of mass treatment for inaccessible herds of ruminants that will allow flexibility in strategic treatment programs based on seasonal transmission and other factors. More reliable cost-benefit assessments, more sensitive diagnostic indicators, and better knowledge of pathophysiologic mechanisms of damage by parasites will assist greatly in identifying the economically important effects against which economical control programs can be targeted.

The opportunities for development and evaluation of novel prophylactic, diagnostic, and management approaches for animal parasitism are close at hand if the spectacular advances in molecular biology, immunology, computer science, and ecologic methodologies are assimilated in present research efforts. Although the emphasis of this report is on applied research and identification of approaches for the immediate future, the importance of more basic research on animal parasites and discoveries in other areas of modern biology and medicine are recognized as the essential pacesetters of the future. There is increasing concern by agricultural research workers that renewal of this base of fundamental knowledge is greatly needed. In this context, studies on the physiology, behavior, antigenicity, and genetic makeup of parasites, protective host responses, and mechanisms of tissue destruction and invasion by veterinary parasites are essential. Veterinary parasitologists must study host-parasite interactions directly with minimal reliance on rodent model systems; although this has disadvantages it offers special opportunities for research that is concurrently applied and fundamental. While the livestock industry can expect continuous progress on current problems, a long-term investment in basic research must be made for the future.
Use of immunofluorescence, Gram's staining, histologic examination, and seroagglutination in the diagnosis of porcine colibacillosis
Authors: Francis David H.
Published: February 2025

An indirect fluorescent antibody (ifa) test of ileal impression smears for K88, K99, and 987P pilus antigens was compared with histologic examination and seroagglutination of Escherichia coli isolates for efficacy in determining colibacillosis in pigs. Histologic examination appeared to be more effective than the ifa test in revealing colonization of the ileum by bacteria. However, histologic examination revealed little about the nature of the colonizing bacteria. Correlation between bacterial adherence, as observed in histologic sections of ileum, and the presence of bacteria with adherence pili, as determined by ifa testing, was 91%. Results of seroagglutination for pilus antigens correlated with results of histologic examination in only 84% of the cases. Pilus antigens were not identified by ifa testing or seroagglutination in 5% of the cases in which adherent bacteria were observed in histologic sections of the small intestine.

Because little preparation time was required for the ifa test, results were available within 2 hours of necropsy. In contrast to histologic examination, the ifa test made possible identification of the colonizing organism as E coli and revealed the type of pilus antigen present. Adherence pili were identified more frequently by ifa testing than by seroagglutination.

Examination of Gram's-stained ileal impression smears was useful in screening for colibacillosis in pigs. Bacterial adherence was found in positive correlation with the number of gram-negative bacilli observed. Bacterial adherence rarely was observed in histologic sections of ileum when smears contained ≤ 10 gram-negative bacilli/1,000 × microscopic field.

Each diagnostic test compared offered advantages and disadvantages over the other tests. Seemingly, concurrent use of several of these tests, rather than one, should be used in the diagnosis of porcine colibacillosis.
Prevalence of antibodies to Mycoplasma hyopneumoniae in Iowa swine
Authors: Young T. F. , Ross R. F. , Drisko Jennifer
Published: February 2025

The prevalence of complement-fixing antibodies to Mycoplasma hyopneumoniae was determined in 7,321 sera collected from breeding swine of various ages. Samples were selected randomly in approximate proportion to the number of hogs marketed annually from each of 9 crop-reporting areas in Iowa. Testing was accomplished by means of a Microtiter complement-fixation test. Of the 7,321 sera, 22% had antibody titers of 1:4 or greater to M hyopneumoniae. Of the 597 herds sampled, 60% or 357 had at least 1 animal with a titer of 1:4 or greater. Use of the chi-square association test indicated that animals which were M hyopneumoniae-positive were more often Haemophilus pleuropneumoniae-positive than those that were M hyopneumoniae-negative.
Blood volume, heart rate, and left ventricular ejection fraction changes in dogs before and after exercise during endurance training
Authors: Mackintosh I. C. , Dormehl Irene C. , van Gelder A. L. , du Plessis Marijke
Published: February 2025

In Beagles (n = 5) after 7 weeks' endurance training, resting blood volume increased by an average of 13.1%. Resting heart rates were not significantly affected, but heart rates measured 2 minutes after exercise were significantly lower after the endurance training than before. Left ventricular ejection fractions determined by radionuclide angiography from 2 minutes after exercise showed no significant changes in response to a single exercise period or over the 50 days' training.
Comparison of pyrimidine 5′nucleotidase activity in erythrocytes of sheep, dogs, cats, horses, calves, and Mongolian gerbils
Authors: George Jeanne Wright , Duncan J. Robert , Mahaffey Edward A.
Published: February 2025

Pyrimidine 5′nucleotidase (P5N) activities of erythrocytes for Mongolian gerbils, cats, dogs, sheep, horses, and calves were measured, using a radiometric technique with [14C]cytidine monophosphate as the substrate. Erythrocytes of gerbils had the highest activity [1,177.1 ± 133.6 mU/g of hemoglobin (Hb)]. Feline erythrocytes had 327.4 ± 204.4 mU/g of Hb. Canine erythrocytes had 148.0 ± 19.8 mU/g of Hb. Ovine erythrocytes (44.3 ± 20.9 mU/g of Hb), equine erythrocytes (30.0 ± 15.9 mU/g of Hb), and bovine erythrocytes (14.1 ± 6.9) had relatively low P5N activity.

The P5N activity was approximately proportional to the reticulocyte percentage of and inversely proportional to the mean erythrocyte life span in these species.
Effects of dexamethasone and surgical hypotension on hepatic morphologic features and enzymes of dogs
Authors: Dillon A. R. , Sorjonen D. C. , Powers R. D. , Spano S.
Published: February 2025

Effects of corticosteroids and surgical stress on hepatic morphologic features and enzymes were studied in 18 mature dogs of mixed breeding: group 1, control (n = 3); group 2, dexamethasone (n = 5); group 3, dexamethasone and surgery (n = 5); and group 4, surgery (n = 5). Dexamethasone (2.2 mg/kg of body weight twice a day subcutaneously) was administered for 8 days in groups 2 and 3 dogs. All dogs were anesthetized with thiopental for 10 minutes on days 0, 2, and 4. On day 2, dogs in groups 3 and 4 were intubated and maintained on methoxyflurane and oxygen, and a liver biopsy, hemilaminectomy (T13-L1), and 15 minutes of hypotension (75/45 mm of Hg) induced by methoxyflurane were done. Serum alkaline phosphatase (alp) activity, alp isoenzymes, and alanine aminotransferase (alt) activity were determined on days 0, 2, 3, 5, and 8. All dogs were euthanatized and necropsied on day 8.

Serum hepatic enzyme activity and hepatic morphologic characteristics were normal for group 1 control dogs. The mean alp and alt were significantly (P < 0.05) increased in dogs in groups 2, 3, and 4. In group 2, the mean alp (days 5 to 8) and alt (day 8) were significantly (P < 0.05) increased. In group 3, the mean alp and alt activities were significantly increased on days 2 to 8. In group 4, the mean alp was significantly increased on days 2 to 8 and the mean alt was significantly increased on days 3 and 5. All other values were normal. A single isoenzyme band (Rf = 0.399 ± 0.023, mean ± sd) was identified in all dogs.

Hepatic morphologic changes attributed to dexamethasone were mild-to-moderate vacuolation in a diffuse distribution on day 2 (group 3) and aggregates of moderate-to-severe vacuolation in mainly a periportal distribution on day 8 (groups 2 and 3). Based on differential staining techniques, dogs in groups 2, 3, and 4 had similar glycogen and neutral fat content as did group 1 control dogs.

Thiopental did not induce hepatic enzyme or hepatic cell morphologic changes. The hepatopathy induced by dexamethasone alone microscopically preceded the increase in alp (5 days); however, the increase in alt was not consistent (2 of 4 dogs). The increase in alp and alt in group 4 after surgery was consistent with a single hepatic insult (alt peaked on day 3 and decreased to base line on day 8, alp peaked on day 5). The persistent increase in alt and alp after surgery indicated that dexamethasone did not protect the liver from the insult and may have impaired the repair process.
Disseminated intravascular coagulation in experimental intestinal strangulation obstruction in ponies
Authors: Pablo Luisito S. , Purohit Ram C. , Teer Pat A. , Newton Joe C. , Hammond Linda S.
Published: February 2025

Total strangulation obstruction of the caudal part of the jejunum was induced in 3 groups (each of 3 ponies) for 2, 4, and 6 hours. Coagulation tests which included blood platelet counts, prothrombin time, activated partial thromboplastin time, activated coagulation time, plasma fibrinogen level, and fibrin/fibrinogen degradation products assay were performed at specified time intervals for 1 week or until death of the experimental ponies. Another 3 ponies (sham-operated) were similarly treated, except that intestinal strangulation obstruction (iso) was not induced. Necropsy was done on ponies that were euthanatized 9 days after the sampling period and on 2 ponies that died.

Six hours of iso resulted in severe ischemic damage to the intestines, characterized by hemorrhagic infarction, with or without perforation, in ponies that died, and total loss of mucosa with moderate to severe fibrosis of the intestinal wall in the surviving pony of this group. This damage was associated with significant coagulopathies, notably prolonged prothrombin time and activated partial thromboplastin time, decreased blood platelets count, and the presence of high levels of fibrin/fibrinogen degradation products (40 µg/ml). These laboratory findings are indicative of disseminated intravascular coagulation. In contrast, the jejunal segments of the ponies subjected to 2 and 4 hours of iso were viable as revealed by histopathologic examination. There were no significant changes found in their coagulation profiles. In this experimental model it was possible to detect disseminated intravascular coagulation due to intestinal ischemia through the use of selected coagulation tests only if severe damage associated with prolonged obstruction of the intestines occurred.
In vitro effect of combinations of antimicrobial agents and EDTA-tromethamine on certain gram-positive bacteria
Authors: Wooley R. E. , Jones M. S. , Gilbert J. P. , Shotts E. B.
Published: February 2025

Combinations of EDTA-tromethamine and 7 antimicrobial agents (chloramphenicol, nalidixic acid, oxytetracycline, penicillin, polymyxin-B, streptomycin, and a triple sulfonamide preparation) were tested for synergistic activities against Staphylococcus aureus, Corynebacterium renal, Listeria monocytogenes, Erysipelothrix rhusiopathiae, and a β-hemolytic streptococci. Two in vitro tests were used—minimal inhibitory concentrations of the drugs and a 2-dimensional Microtiter checkerboard technique. A slight synergistic action was seen when L monocytogenes was exposed to combinations of penicillin-EDTA or streptomycin-EDTA.
Clinical responses of dogs to experimentally induced Dipetalonema reconditum infection
Authors: Lindemann Bruce A. , Evans Teri L. , McCall John W.
Published: February 2025

Six male and 6 female Beagles, 6 to 7 months old, were allotted to 2 groups: group I—inoculated subcutaneously with 30 Dipetalonema reconditum infective larvae/dog, and group II—noninoculated controls. Group comparisons were made in regard to hematologic values, Knott test results, body weights, blood urea nitrogen, total serum protein, serum albumin and alanine aminotransferase and creatine kinase activities. Routine urinalysis data were compared at 1 week before and at 28 weeks after the inoculations.

Mean total leukocyte counts were significantly (P < 0.05) greater in group I dogs than in group II dogs at postinoculation weeks (piw) 4,5, and 7 to 12, and mean eosinophil counts were significantly greater in group I dogs at piw 3 to 11, 13 to 15, 20, and 23 to 24. Microfilariae were detected as early as the 10th week and sporadically thereafter. Only 1 D reconditum adult worm was recovered from all of the inoculated dogs.

Five other dogs (group III) with chronic, patent experimentally induced dipetalonemiasis, were evaluated with the same tests at piw 70 to 89. Eosinophilia (> 750 cells/µl) was present in 4 of 5 dogs; lymphocytosis (> 4,800 cells/µl) was evident in 1 dog. Proteinuria (≥ 30 mg/dl) was detected in 3 of 4 dogs with chronic dipetalonemiasis.
Canine immunoreactive insulin quantitation using, five commercial radioimmunoassay kits
Authors: Stockham Steven L. , Nachreiner Raymond F. , Krehbiel Janver D.
Published: February 2025

Five commercial radioimmunoassay (ria) kits developed for quantitation of human immunoreactive insulin (iri) were evaluated for their capability to quantitate canine iri. Evaluation criteria included precision, dilutional parallelism, sensitivity, and comparison of iri concentration in 4 control sera.

One ria kit had good dilutional parallelism, consistently good precision, and adequate sensitivity. Other ria kits had poorer performance in dilutional parallelism or precision. No ria kit quantitated the same iri concentrations in all 4 control sera as did another. The results indicated that quantitation of canine iri by some commercial ria kits (for human use) may not be reliable. Variations in iri concentrations quantitated indicated that reference intervals for healthy dogs should be established for each insulin ria
Antiparasitic efficacy of ivermectin in naturally parasitized sheep
Authors: Yazwinski T. A. , Greenway T. , Presson B. L. , Pote L. M. , Featherstone H. , Williams M.
Published: February 2025

Sixteen sheep harboring naturally acquired parasitisms were allocated to 1 of 2 treatment groups: (i) sheep given ivermectin in an oral solution at the dosage rate of 200 µg/ kg of body weight, and (ii) those given the vehicle at a dosage rate of 0.25 ml/kg. All animals were necropsied at 2 weeks after treatment. Parasites and percentages of parasitic reductions, as demonstrated in this trial, were: Dictyocaulus filaria (99.4%), Oestrus ovis first stage instars (100%), Trichuris ovis (98.9%), Strongyloides papillosus (99.8%), Nematodirus spathiger (100%), arrested 4th stage Nematodirus spp (96.2%), Trichostrongylus colubriformis (100%), Taxei (100%), Oster tagia circumcincta (100%), Haemonchus contortus (100%), and arrested Haemonchus spp 4th stage larvae (99.9%). The sheep showed no adverse effects due to ivermectin or vehicle administration.
Plasma coagulation factor abnormalities in dogs with naturally occurring hepatic disease
Authors: Badylak Stephen F. , Dodds W. Jean , Van Vleet John F.
Published: February 2025

The plasma values for factors (F)VII, FVIII:C, FVIIIR:Ag, FIX, FX, and FXI and the thrombin clotting time (tct) were determined for 28 dogs with naturally occurring hepatic disease. The major morphologic type of hepatic disease present in a given dog, as determined by hepatic biopsy and histopathologic examination, was degeneration (12 dogs), inflammation (9 dogs), cirrhosis (3 dogs), or neoplasia (4 dogs). A specific morphologic diagnosis also was made for each dog in the study. Plasma coagulation factor values and screening tests were consistently abnormal in > 50% of the dogs with each type of hepatic disease as follows: degeneration—decreased FXI; inflammation—increased FVIIIR:Ag; cirrhosis—shortened tct, decreased FIX, FX, and FXI, and increased FVIIIR:Ag; and neoplasia—shortened tct, decreased FVIII:C, and increased FVIIIR:Ag. The plasma coagulation factor values were compared with serum alanine aminotransferase (alt) and alkaline phosphatase (alp) activities, fibrinogen-fibrin degradation product (fdp) concentration, and the prothrombin time (pt) and activated partial thromboplastin time (aptt) to determine the sensitivity and specificity of each test in detection of hepatic disease. Of all dogs with hepatic disease, 93% had at least 1 abnormal coagulation test value. The pt and aptt were abnormal in 50% and 75%, respectively, of these same dogs. Increased serum alt and alp activities were present in 61% and 50%, respectively, and fdp concentrations were increased in 14% of dogs with hepatic disease. The results showed that certain individual coagulation test values were more sensitive and specific for detection of the different major types of hepatic disease than either serum alt or alp activities, pt or aptt values, or fdp concentrations.
Experimental Toxocara canis infection in cynomolgus macaques (Macaca fascicularis)
Authors: Glickman Lawrence T. , Summers Brian A.
Published: February 2025

Visceral larva migrans was produced in 16 cynomolgus macaques (Macaca fascicularis) experimentally inoculated with 45,000 embryonated eggs of Toxocara canis as a single bolus or in 3 divided doses. The hematologic and serologic changes were similar to those observed in children with visceral Toxocara infection. Neurologic signs developed in 3 animals and were characterized by ataxia and nystagmus. Growth rates were diminished in inoculated animals when compared with the rates in noninoculated controls. Diagnostic antibody titers as measured by enzyme-linked immunosorbent assay were noted in all inoculated macaques by the 4th week, and these titers persisted during the 7-month period of observation. Antibody to Toxocara was not detected in the aqueous or vitreous humors. Lesions comprised severe granulomatous hepatitis and encephalomyelitis. Intraocular lesions associated with larval migration were not observed.
Simulium jenningsi Malloch (Diptera: Simuliidae): A vector of Onchocerca lienalis Stiles (Nematoda: Filarioidea) in New York
Authors: Lok James B. , Cupp Eddie W. , Bernardo Michael J.
Published: February 2025

Biting flies were collected from the umbilical areas of Onchocerca lienalis-infected cattle in New York (state) from June through September of 1980. Of the 766 flies collected, 705 were Simulium jenningsi. Microfilariae were detected in the midguts of 37 (50%) of 73 females dissected immediately after the flies had fed. The mean number of larvae per positive fly (fly with microfilariae) was 15.2. Third-stage larvae were recovered from 25 (21.9%) of 114 S jenningsi dissected 8 to 13 days after they had fed on the infected cattle; the mean number of 3rd-stage larvae per positive fly was 3.5. Dissections of flies performed on days 1 through 7 after feeding yielded various numbers of 1st and 2nd-stage larvae from the thoracic muscles. Ovarian dissections performed on 304 S jenningsi attacking cattle indicated an overall parous rate of 58%. Naturally occurring infections with filarial larvae indistinguishable from O lienalis were found in 7.3% of the parous females. Three of these flies, or 1.7% of the parous collection, harbored 3rd-stage larvae. The onset of naturally occurring filarial infections in the population of S jenningsi coincided with a peak in the parous rate in late June. Thereafter, filarial infections were generally detected when the parous rate was above 50%.