bluuebunny/crossref_metadata_2025 huggingface dataset:
Pathogenesis of Feline Infectious Peritonitis: Pathologic Changes and Immunofluorescence
Authors: Weiss Richard. C. , Scott F. W.
Published: February 2025

Feline infectious peritonitis (fip) was experimentally induced in fip virus (fipv) antibody-positive and antibody-negative kittens after challenge exposure to live-virus aerosol. Seropositive kittens developed antiviral immunofluorescence and lesions more rapidly after challenge exposure than did seronegative kittens. In seropositive kittens, fipv antigen was present in macrophages and large mononuclear cells in tracheobronchial lymph nodes, lungs, and trachea on postchallenge-exposure day (pcd) 2; in liver and spleen on pcd 3; in kidneys and omentum on pcd 4; and subsequently in nasal turbinates, thoracic and abdominal lymph nodes, thymus, bone marrow, parotid salivary gland, eyes, and brain. Initial antiviral immunofluorescence on pcd 2 coincided with the onset of viremia and vascular lesions. Systemic lesions characterized by perivascular necrotizing pyogranulomatous inflammation, phlebitis and thrombosis, fibrinous serositis, and generalized lymphoid necrosis developed on pcd 3 and 4. Coronavirus-like particles were observed by electron microscopy in cytoplasmic vacuoles or smooth endoplasmic reticulum of degenerating macrophages in inflammatory lesions.

In seronegative kittens, antiviral immunofluorescence in tracheobronchial lymph nodes was first detected on pcd 5, and viremia occurred on pcd 6. Systemic necrotizing lesions, comparable with those observed in seropositive kittens on pcd 3 or 4, did not occur in seronegative kittens until pcd 13 or 16.

In both groups of kittens, initial viral infection in regional lymphoreticular tissue was followed by viremia and infection of macrophages in reticuloendothelial organs (liver, spleen, lymph nodes) and perivascular locations. The accelerated onset of infection and lesions indicative of an Arthus-type reaction in challenge-exposed seropositive vs seronegative kittens further supports the immune-mediated pathogenesis of fip.
Alterations of Prothrombin Time and Activated Partial Thromboplastin Time in Dogs with Hepatic Disease
Authors: Badylak Stephen F. , Van Vleet John F.
Published: February 2025

Reference intervals for prothrombin time (pt) and activated partial thromboplastin time (appt) of undiluted and serial dilutions of citrated platelet-poor plasma were determined for 30 healthy dogs.

The pt and aptt were similarly determined for 32 dogs with naturally occurring hepatic disease. Hepatic disease was confirmed by histopathologic examination of hepatic biopsy materials and comprised degeneration (13 dogs), inflammation (11 dogs), cirrhosis (4 dogs), and neoplasia (4 dogs). Coagulation test values were compared with serum alanine aminotransferase, alkaline phosphatase, and γ-glutamyl transpeptidase activities and Bromsulphalein retention for sensitivity in detecting hepatic disease in the dog. Coagulation test results were at variance with reference values in 66% of the 32 dogs with hepatic disease; serum alanine aminotransferase, alkaline phosphatase, and γ-glutamyl transpeptidase were increased in 59%, 72%, and 75%, respectively, and Bromsulphalein retention was increased in 22% of the 32 dogs. Thus, the pt and aptt were sensitive indicators of hepatic disease. However, the pt and aptt lacked specificity for any given hepatic disease. The sensitivity of the coagulation tests for detecting hepatic disease was enhanced by using dilutions of citrated platelet-poor plasma. Only 15% of dogs with hepatic disease showed variances from reference values in the coagulation tests done with undiluted plasma, but 66% showed variances in the tests with dilutions of plasma.

Coagulation tests were also done in 13 dogs with normal hepatic function and morphology, but with various extra hepatic diseases: chronic renal disease (5 dogs), dirofilariasis 44 dogs), encephalitis (1 dog), cutaneous disease (2 dogs), and femoral fracture (1 dog). Twelve of the 13 dogs had coagulation test values within the reference intervals.
Quantitative Aspects of Binding of Canine Serum Immunoglobulins to Staphylococcus aureus Protein A
Authors: Miele James A. , Krakowka Steven
Published: February 2025

Quantitative interactions of Staphylococcus aureus protein A (spa) and canine immunoglobulins (Ig) are described. The S aureus Cowan strain I bound canine IgG, IgM, and IgA, whereas binding was not observed with the spa-negative Wood 46 strain of S aureus. In a quantitative adsorption experiment, the results indicated that IgA, though present in the lowest amounts in the samples, appeared to be substantially bound by spa. Adsorption of sera with spa-negative Wood strain bacteria resulted in nonspecific protein losses in supernatants of 0% to 15%.
Infection of Splenectomized Calves with Anaplasma ovis
Authors: Kuttler K. L.
Published: February 2025

An Anaplasma was not recovered from 2 splenectomized calves at 17 days after A ovis inoculation, but was recovered from 1 of the calves at 177 days after inoculation. In a 3rd calf exposed to A ovis, an Anaplasma was recovered at 177 and 262 days after inoculation. The Anaplasma recovered from these calves was determined to be A ovis on the basis of cross-infectivity trials, using Anaplasma marginale.
Lysates of Turkey-Grown Pasteurella multocida: Protection Against Homologous and Heterologous Serotype Challenge Exposures
Authors: Rimler R. B. , Rhoades K. R.
Published: February 2025

Pasteurella multocida organisms were separated from the blood of experimentally infected turkeys by differential centrifugation. An average of 92% of the residual host-cell contamination was removed from the pasteurellas by density gradient centrifugation in sucrose. Sucrose suspensions of the turkey-grown pasteurellas partially lysed after freezing and thawing. Treatment of freeze-thawed suspensions with DNAse, hyaluronidase, lysozyme, edta, and Triton X-100 did not influence their ability to induce protection against homologous and heterologous serotype challenge exposures. Lysozyme, edta, and Triton X-100 completely lysed the pasteurellas and rendered the cross-protection factor(s) filterable. Addition of adjuvant to completely lysed P multocida did not appear to enhance protection in turkeys against heterologous serotype challenge exposure. Adjuvant added to the pellet or supernatant fraction of centrifuged complete lysate enhanced protection in turkeys. Vaccines prepared from different serotypes of turkey-grown P multocida protected chickens and mice against homologous and heterologous serotype challenge exposures.
Rabies Virus Tropism in Naturally Infected Skunks (Mephitis mephitis)
Authors: Howard D. R.
Published: February 2025

Tissue distribution of rabies virus antigen was studied in 6 naturally infected skunks (Mephitis mephitis), using the fluorescent antibody test. Viral antigen was detected in all tissues and organs examined. Viral antigen was also detected in 1 embryo from a pregnant skunk.
Atrophic Gastritis in a Hermann's Tortoise (Testudo hermanni) and Two Red-Eared Turtles (Chrysemys scripta elegans)
Authors: Zwart P. , van der Gaag Ingrid
Published: February 2025

Atrophic gastritis, with concomitant pseudopyloric metaplasia, occurred in a tortoise and 2 turtles. Mild gastritis, with some atrophy of gastric glands and minor loss of oxynticopeptic cells which were replaced by mucous cells, was observed in the Hermann's tortoise (Testuda hermanni). Chronic atrophic gastritis, characterized by inflammation and atrophy of glandular elements, with changes resembling pseudopyloric metaplasia, was seen in 2 red-eared turtles (Chrysemys scripta elegans). The 3 animals had extensive renal lesions with von Kossa's stain-positive mineral deposits in the stomach and in other soft tissues.

In 2 clinically normal red-eared turtles, the gastric fundic glands were of compound tubuloacinar type, whereas those of the cardiac and pyloric regions had a simple tubular structure.
Effects of long-term primidone and phenytoin administration on canine hepatic function and morphology
Authors: Bunch S. E. , Castleman W. L. , Baldwin B. H. , Hornbuckle W. E. , Tennant B. C.
Published: February 2025

Primidone, phenytoin, or phenytoin and primidone in combination were given to healthy Beagle dogs for 6 months. Serum biochemical changes in dogs given primidone alone or phenytoin and primidone in combination for the entire 6-month test period included increased activities of alanine aminotransferase, alkaline phosphatase (ap), and γ-glutamyltransferase, and decreased concentrations of albumin and cholesterol. Changes in dogs given phenytoin alone were limited to increased ap activity and decreased albumin concentration. Sulfobromophthalein excretion and conjugated bile acid concentration were within normal limits.

All dogs given primidone alone or phenytoin alone remained clinically healthy throughout the treatment period. Three of 8 dogs given both drugs in combination became clinically ill after 9, 14, and 15 weeks of treatment, and were euthanatized. Two of the dogs developed clinical jaundice. In addition to the serum biochemical abnormalities observed in clinically healthy dogs, these dogs developed hyperbilirubinemia, delayed sulfobromophthalein excretion, and increased conjugated bile acid concentrations. Histologic examination of the liver showed intracanalicular casts of bile pigment typical of intrahepatic cholestasis in all 3 dogs.

Histologic findings characteristic of treated dogs included hepatocellular hypertrophy attributable to hyperplasia of the smooth endoplasmic reticulum. Single-cell necrosis and multifocal lipidosis were observed in individuals of all treatment groups. Electron microscopy of the liver showed dilated bile canaliculi and damaged sinusoidal epithelium in dogs given both drugs.

The elevated serum ap activity, associated with anticonvulsant drug therapy, was found to be exclusively the liver isoenzyme by cellulose acetate electrophoresis. The hepatic ap was localized to primarily the canalicular membranes by enzyme histochemistry. There was a statistically significant positive correlation between the ap activities of liver and serum.

The results of this study indicate that long-term administration of anticonvulsant drugs to dogs is associated with clinical, serum biochemical, and histologic evidence of hepatic dysfunction. High drug dosage contributed most to abnormal serum biochemical test results, and combining phenytoin with primidone was responsible for more severe electron microscopic lesions of the liver of surviving dogs and for the death of 3 dogs.
A new field strain of equine abortion virus (equine herpesvirus-1) among Kentucky horses
Authors: Allen George P. , Yeargan Michelle R. , Turtinen Lloyd W. , Bryans John T.
Published: February 2025

From restriction endonuclease characterization of the DNA of 317 isolates of equine abortion virus (equine herpesvirus-1; ehv-1) from 176 epizootically unrelated outbreaks of equine virus abortion occurring over 24 years in Kentucky, an epizootic pattern and variation of the virus have emerged. Two electropherotypes of ehv-1 (1P and 1B) accounted for > 90% of the nonvaccine-related abortion isolates examined. From 1960 to 1981, ehv-1 1P was the predominant isolate circulating in the central Kentucky area and the cause of > 80% of ehv-1-related abortions. In 1981, the occurrence of isolate 1B-related abortions began to increase, and since 1982, 1B has become the most frequently recovered isolate of ehv-1 from aborted fetuses.
Serotyping of Haemophilus pleuropneumoniae by rapid slide agglutination and indirect fluorescent antibody tests in swine
Authors: Rapp V. J. , Ross R. F. , Erickson B. Zimmermann
Published: February 2025

One hundred and forty-one isolates of Haemophilus pleuropneumoniae from Iowa and Illinois swine were characterized morphologically and biochemically and serotyped by rapid slide agglutination (rsa) and indirect fluorescent antibody (ifa) tests. Hyperimmune antisera were produced in rabbits using inactivated whole-cell suspensions of the reference strains for H pleuropneumoniae serotypes 1 to 7 and strain 202, representing the taxon “minor group.” Cross testing of the reference strains and reference antisera indicated the antisera to be essentially serotype-specific, although reactivity of some antisera with heterologous strains was observed.

Cultures of the 141 isolates formed adherent or smooth colonies or mixtures of these colony forms. Adherent and smooth colony types were found in all serotypes identified. Microscopic and biochemical characteristics of all isolates were typical of those previously described for H pleuropneumoniae.

The overall incidence of H pleuropneumoniae serotypes was serotype 5, 55.3%; serotype 1, 34.0%; serotype 7, 7.8%; and nontypeable, 2.8%, Comparing the 2 test procedures, 87.2% of the isolates could be typed by rsa, and 66.0% could be typed by ifa. Cross-reactions between serotype 4 antisera and serotype 5 and 7 isolates were common with the ifa test. The reactions with serotype 7, but not serotype 5, were eliminated by cross adsorption of serotype 4 antisera. There was good correlation between the 2 test procedures, but rsa was judged to be more specific and sensitive than ifa.
Diagnosis of Corynebacterium pseudotuberculosis infections in sheep, using an enzyme-linked immunosorbent assay
Authors: Maki Leroy R. , Shen Shueh-Hui , Bergstrom Robert C. , Stetzenbach Linda D.
Published: February 2025

Lambs infected with Corynebacterium pseudotuberculosis (ovis) by injecting suspensions of live bacteria into the wool-free area of the axilla developed antibody against cell wall antigens and antitoxin, as measured by the enzyme-linked immunosorbent assay. The toxin was a better antigen for measuring infection than was the cell wall antigen. The enzyme-linked immunosorbent assay appeared to be as sensitive as the antihemolysin inhibition test for detecting antitoxin and was easier to perform.
Pharmacokinetics of flunixin meglumine in dogs
Authors: Hardie Elizabeth M. , Hardee Gregory E. , Rawlings Clarence A.
Published: February 2025

The pharmacokinetics of flunixin meglumine, a potent nonsteroidal anti-inflammatory agent, were studied in 6 intact, awake dogs. Plasma samples were obtained up to 12 hours after iv administration of flunixin meglumine. Flunixin concentration was determined, using high performance liquid chromatography. Plasma data best fit a 2-compartment model. Distribution half-life was 0.55 hour; elimination half-life was 3.7 hours; volume of distribution (area) was 0.35 L/kg; volume of distribution at steady state was 0.18 L/kg; volume of the central compartment was 0.079 L/kg; and total body clearance was 0.064 L/hr/kg. Flunixin concentrations obtained over a 6-hour period in 3 dogs with septic peritonitis did not differ significantly from those obtained from healthy dogs.
Scanning electron microscopy of the canine atrioventricular bundle and moderator band
Authors: Sandusky George E. , White Sandy L.
Published: February 2025

The atrioventricular (av) bundle and the moderator band in the canine heart were examined by scanning electron microscopy. The av bundle and the moderator band both were comprised of large, cylindrically shaped cells. These cells were highly organized into bundles, with minimal lateral communication between bundles. There was extensive cell-to-cell communication between cells within a bundle. The end branching of individual cells was prominent, with some interbundle communication. These results are discussed in relationship to the electrophysiologic properties of the av bundle and the conduction velocity.
Dimensions of the rabbit femur during growth
Authors: Rudicel Sally , Lee Kendrick E. , Pelker Richard R.
Published: February 2025

In the rabbit, the femur grew rapidly in length during the first 4 weeks of life of the animal. Growth continued at a slower rate up to 8 to 10 weeks of age and then reached a plateau. A similar growth pattern (rapid increase followed by a plateau) was seen for the dimensions of the femoral head, neck, and shaft. Significant growth differences between the left and right femurs did not occur.
Production responses of lactating dairy cows and heifers given thiabendazole at parturition
Authors: Fetrow John , Johnstone Colin , Bartholomew Richard
Published: February 2025

A field trial was conducted to examine the effects on productivity of dairy cattle in 6 herds given thiabendazole at parturition. Criteria examined were milk and fat production, calving interval, services per conception, culling rate, and (in a subset of cows) hematologic response. Analysis of the data for all cows as a group did not indicate a significant effect. For first-calf heifers in 1 herd, a significant (P < 0.01) and economically important increase in milk production was observed; why the effect was seen was not determined.
Diversity of African swine fever virus
Authors: Pan I. C. , Hess W. R.
Published: February 2025

An African swine fever virus is an heterogeneous population, consisting of clones having different biological characteristics in respect to hemadsorption, virulence, infectivity, plaque size, and antigenic determinants. The following observations were made: (1) Nonhemadsorbing virus (nhv) have been segregated from field isolates from Haiti (ht-1) and a bone marrow- and buffy coat-passaged Portugese isolate (L′6OBM89BC1) and appear as a major, minor, or equal mixture with hemadsorbing viruses in the virus population. (2) Biological characteristics of the virus inoculated into pigs often differed from viruses isolated later from the same pigs. (3) Virulence and nonhemadsorbing characteristics of isolated clones were genetically stable. (4) The lethal effect of 2 nhv clones of L′6OBM89BC1 virus was dose-dependent; small doses of virus induced immunologic deaths or recoveries from the clinical disease in pigs, and large doses induced acute deaths. (5) The nhv of Lisbon isolate of 1960 (L′60) and ht-1 isolate share the same antigenic determinants for inducing protection. (6) Tengani isolate contained clones of distinctly different antigenic determinants, not shared by L′60 or ht-1 isolate that enabled it to overcome the protection induced by the other clones. (7) Passaging of an African swine fever virus isolate in pigs or cell cultures may readily alter the proportions of the different clones in the population and thereby change its overall characteristics. (8) A new virus population with atypical hemadsorption was found in ht-1 field isolate and L′6OBM89BC1 virus.
Effects of phenylbutazone and anabolic steroids on adrenal and thyroid gland function tests in healthy horses
Authors: Morris Debra Deem , Garcia Marolo C.
Published: February 2025

Adrenal and/or thyroid gland function tests were evaluated in horses at various times during short-term therapy with phenylbutazone, stanozolol, and boldenone undecylenate. There were no significant treatment or time effects on mean basal plasma cortisol concentrations in horses during treatment with the following: phenylbutazone, given twice daily (4 to 5 mg/kg, iv) for 5 days; stanozolol, given twice weekly (0.55 mg/kg, im) for 12 days; boldenone undecylenate, given twice weekly (l.1 mg/kg, im) for 12 days; or nothing. There was no significant effect of phenylbutazone treatment on the changes in plasma cortisol concentration during the combined dexamethasone-suppression adrenocorticotropic hormone (acth)-stimulation test. Plasma cortisol concentration was significantly decreased from base line at 3 hours after dexamethasone administration and was significantly increased from base line at 2 hours after acth in all horses (P < 0.05). Likewise, the stimulation of basal plasma cortisol concentrations at 2 hours after administration of acth (P < 0.05) was not affected by treatment with stanozolol or boldenone undecylenate.

There were no significant treatment effects on mean basal plasma concentrations of thyroxine (T4) or triiodothyronine (T3) among horses during the following treatments; stanozolol, given twice weekly (0.55 mg/kg, im) for 12 days; boldenone undecylenate, given twice weekly (1.1 mg/kg, im) for 12 days; or nothing. There was a significant time effect on overall mean basal plasma T4 and T3 concentrations (P < 0.05): plasma T4 was lower on day 8 than on days 1, 10, and 12; plasma T3 was higher on day 8 than on days 4 and 12. Treatment with neither anabolic steroid significantly affected the increases in plasma concentrations of T4 and T3 in horses after thyroid-stimulating hormone (tsh) was administered. Plasma concentrations of T4 and T3 were significantly elevated above base line at 3 and 6 hours after tsh was given in all horses (P < 0.05).

Under the conditions of the study, it can be concluded that (i) short-term treatment of horses with phenylbutazone does not significantly affect basal plasma cortisol concentration, nor response of the pituitary-adrenal axis to dexamethasone or acth; (ii) short-term treatment of horses with 2 different anabolic steroids (stanozolol and boldenone undecylenate) does not significantly affect basal concentrations of plasma cortisol, T4, and T3, nor response of the pituitary-adrenal axis to acth or response of the pituitary-thyroid axis to tsh; and (iii) basal plasma concentrations of T4 and T3 in horses vary over time.
Hemodynamic responses in halothane-anesthetized horses given infusions of dopamine or dobutamine
Authors: Swanson Clifford R. , Muir William W. , Bednarski Richard M. , Skarda Roman T. , Hubbell John A. E.
Published: February 2025

The hemodynamic changes induced by constant infusions of dopamine or dobutamine (each 3, 5, and 10 μg/kg/min) were observed in halothane-anesthetized horses. Left ventricular dp/dt and cardiac output were increased in horses given dobutamine at dosage of 3 μg/kg/min and in those given either of the drugs at dosages of 5 and 10 μg/kg/min. Concomitant increases in systemic arterial blood pressure occurred at lower infusion dosage rates of dobutamine than those of dopamine and were modulated by dosage-related changes in peripheral vascular resistance that were different between the 2 drugs. Total peripheral vascular resistance was unchanged by the 3 μg/kg/min dosage of dopamine, significantly (P < 0.05) decreased at the 5 μg/kg/min dosage of dopamine, and returned to base line in horses when given the largest dosage. Dobutamine had no effect on total peripheral vascular resistance. Heart rate was significantly (P < 0.05) decreased by the 2 smaller dosages of dobutamine, but returned to base line at the 10 μg/kg/min dosage. Heart rates did not change significantly in response to dopamine over the range of the dosages. Sinus tachycardia with atrioventricular conduction block was noted in some horses given either of the drugs.

The results of the present study indicate that the hemodynamic responses in horses given dopamine or dobutamine infusions are similar to those in other species and are the net result of the different adrenergic pharmacologic profiles of the 2 drugs combined with autonomic nervous system reflexes.
Keratoconjunctivitis sicca; immunological evaluation of 62 canine cases
Authors: Kaswan Renee L. , Martin Charles L. , Dawe Donald L.
Published: February 2025

The etiology of keratoconjunctivitis sicca (kcs) in 62 dogs was evaluated, using immunologic techniques. Using direct fluorescent antibody testing, autoantibodies within the lacrimal, salivary, or pancreatic glands were detected in 5 of 8 dogs tested. Circulating antibodies to the nictitating membrane gland, main lacrimal gland, parotid salivary gland, or mandibular salivary gland were detected using indirect fluorescent antibodies in 9 of 31, 3 of 31, 5 of 31, and 5 of 31 sera, respectively. Using radial immunodiffusion, hyper-γ-globulinemia was detected in 21 of 30 dogs with kcs. Antinuclear antibodies, primarily in a nucleolar pattern, were demonstrated in 20 of 50 dogs with kcs. Lymphocytic infiltrates were evident in 5 of 9 labial salivary biopsies, 2 of 4 parotid gland specimens, 2 of 4 mandibular gland specimens, and 2 of 3 thyroid gland specimens taken from dogs with kcs.

Autoimmune diseases had been previously documented in 4 of 62 dogs. Twenty-five of the 62 dogs (40%) had concurrent problems indicative of an underlying immunologic disorder.
Ultrastructure of schizonts in the liver of cats with experimentally induced cytauxzoonosis
Authors: Simpson Charles F. , Harvey John W. , Lawman M. J. P. , Murray J. , Kocan A. A. , Carlisle J. W.
Published: February 2025

Schizonts in the liver of 2 cats with cytauxzoonosis were studied by both light and electron microscopies. By light microscopy, the cytoplasm of macrophages in the sinusoids and small vascular channels contained schizonts with cytomeres or both cytomeres and mature merozoites.

By electron microscopy, it was determined that schizogony occurred in 4 stages. The earliest stage was the presence of a multilobed structure containing finely granular protoplasm in the cytoplasm of the macrophage. The 2nd stage was an increase in height and number of the lobulations on the surface of the schizont. The 3rd stage involved the development of cytomeres and the appearance of a polar ring and rhoptries in everted sacculations on the cytomere membrane. Nuclei and mitochondria were incorporated into the sacculations before the release of mature merozoites into the host cell cytoplasm.

In the last stage of schizogony, following massive merozoite formation and reduction in size of the schizont, residual nuclei divided by multiple fission. Each nuclear division became incorporated into a developing merozoite having preformed rhoptries, mitochondria, and a polar ring.
Characterization of magnesium-induced urinary disease in the cat and comparison with feline urologic syndrome
Authors: Finco Delmar R. , Barsanti Jeanne A. , Crowell Wayne A.
Published: February 2025

Aggregates of struvite crystals caused urethral obstruction in a high percentage of cats fed moist and dry diets supplemented with Mg oxide. Some of the diets were associated with cystolith formation as well. The percentage of Mg in the experimental diets was a misleading indicator of Mg intake because of differences between moist and dry diets in their caloric density. Magnesium homeostasis was maintained in cats ingesting large quantities of Mg. Tissue (kidney, muscle, and rib) concentrations of Mg were the same in cats fed high Mg and control diets. Plasma Mg concentration was increased only in cats ingesting the largest amount of Mg. Magnesium homeostasis was maintained by a marked increase in urine Mg excretion. However, urine Mg concentration was not directly related to Mg intake, apparently because of differences between diets in intestinal absorption of Mg.

Urethral obstruction of experimental cats was not associated with a transient increase in Mg intake, nor did obstructing cats have higher urine Mg concentrations than did nonobstructing cats fed the same diet. This observation indicates that factor(s) other than urine Mg concentration are important in urethral obstruction.

Cats with urethral obstruction due to naturally occurring disease, feline urological syndrome (fus), had markedly lower urine Mg concentrations than cats fed high Mg diets. This finding refutes the theory that cats develop fus because of primary Mg hyperabsorptive phenomena or because of a primary urinary leak of Mg. It also indicates that factors other than urine Mg concentration are involved in the genesis of naturally occurring urethral obstruction. Another difference between the natural and the induced disease was related to the character of the urinary precipitates. Experimental diets higher in Mg concentration caused urolith formation, which is uncommon with fus. Lower Mg diets caused obstruction with aggregates of crystals, but mucus was not observed. However, in the experimental disease induced in the present study, urinary precipitates were predominantly or exclusively struvite, as has been reported in the natural disease.

Many similarities were seen between the diet-induced disease and fus, but factors in addition to Mg intake are involved in the natural disease. The importance of Mg, compared with the undefined factors, remains to be established.
Adhesion of Corynebacterium pilosum by pili to epithelial cells of bovine vulva
Authors: Hayashi A. , Yanagawa R. , Kida H.
Published: February 2025

Piliated (P+) and nonpiliated (P-) clones of Corynebacterium pilosum were selected, and their adhesion to the epithelial cells of the bovine vulva and vaginal vestibule was examined. The number of P+ bacteria of C pilosum that adhered to vulval epithelial cells was greater than that of P- bacteria. The adhesion of P+ bacteria, but not P- bacteria, to the epithelial cells was inhibited by the antipilus antiserum; therefore, the adhesion of C pilosum to the epithelial cells of the vulva was primarily dependent on the pili. The number of C pilosum that adhered to the epithelial cells of the bovine vulva and of the vaginal vestibule increased by decreasing the pH.
Effect of the morantel sustained-release bolus, used during one grazing season, on the sensitivity of Ostertagia and Cooperia to morantel tartrate in calves
Authors: Newby T. J. , Yazwinski T. A. , Presson B. L. , Holtzen H. M. , Bischoff M. J. , Featherstone H. E.
Published: February 2025

Infective 3rd-stage larvae of Ostertagia and Cooperia, obtained from the feces of nonmedicated and morantel sustained-release bolus (msrb)-treated calves, were orally administered to 2 groups of parasite-free calves. After a 42-day maturation period, a therapeutic dose of morantel tartrate was administered to half of the calves from each group. All calves were necropsied 7 days after treatment. After comparing the nematode counts for the nonmedicated and morantel-treated calves of each group, morantel tartrate was demonstrated to be equally effective against the nonmedicated-derived and msrb-derived nematode populations. The sensitivity of Ostertagia spp and Cooperia spp to morantel tartrate, therefore, was not diminished after use of the msrb for a single grazing season.
Linkage of genes for heat-stable enterotoxin, drug resistance, K99 antigen, and colicin in bovine and porcine strains of enterotoxigenic Escherichia coli
Authors: Harnett N. M. , Gyles C. L.
Published: February 2025

Linkages among genes for production of Escherichia coli heat-stable enterotoxin (st), drug resistance, K99 antigen, and colicin were investigated in 2 bovine and 3 porcine strains of enterotoxigenic E coli. In conjugation experiments, all 5 isolates transferred enterotoxigenicity and the ability to produce K99; 4 of the 5 isolates also transferred antibiotic resistance markers, and 3 colicinogenic strains transmitted the ability to produce colicin. In 2 of the 3 colicin-producing strains, the genes for colicin were located along with those for K99 and st on a single plasmid. One of these 2 strains transferred the genes for tetracycline resistance and production of both mouse-active st (STa) and mouse-inactive st, whereas the other transmitted the gene(s) for STa only. Transformation studies with the 3rd strain revealed that the K99 determinant resided on a 22-megadalton (Mdal)R plasmid, and that STa and colicin production were on a 65-Mdal plasmid. Analysis of the plasmids from the transformation experiments revealed that the larger plasmid was conjugative and the smaller plasmid was nonconjugative; stable cointegrate formation occurred between these 2 plasmids. Genetic information coding for the production of STa and K99 were also present on a single plasmid of approximately 80 Mdal in both noncolicinogenic strains.
Anaplasma marginale infections in American bison: Experimental infection and serologic study
Authors: Zaugg J. L. , Kuttler K. L.
Published: February 2025

Anaplasma marginale was experimentally transmitted from cattle to bison and back to cattle. Of the 2 splenectomized and 1 intact American bison calves (Bison bison) inoculated with a North Texas A marginale stabilate, 1 splenectomized and 1 intact bison exhibited clinical signs of anaplasmosis. Active parasitemias in these bison were observed along with positive reactions in the rapid card agglutination and complement fixation tests. Blood from the infected bison produced disease in splenectomized bovine calves.

Screening tests for anti-Anaplasma antibodies in 178 blood samples collected from adult bison from the National Bison Range, Montana, revealed 1 rapid card agglutination test-positive sample, and 110 negative, 40 suspect, and 28 positive (15.7%) complement fixation test samples.
Rifampin in the horse: Comparison of intravenous, intramuscular, and oral administrations
Authors: Burrows G. E. , MacAllister C. G. , Beckstrom D. A. , Nick J. T.
Published: February 2025

The plasma concentrations and pharmacokinetics of rifampin disposition were determined after a single iv, im, or oral dose of 10 mg/kg of body weight and an oral dose of 25 mg/kg. The overall elimination rate constants per minute were similar for the 10 mg/kg dose (0.0021 ± 0.0004, iv; 0.0017 ± 0.0002, im; and 0.0023 ± 0.0006, orally). The apparent bioavailability was moderate to low for im and oral administrations (59.8% ± 3.2% and 39.5% ± 5.0%, respectively). The rate of absorption was most rapid for oral administration with an absorption half-life of 249.7 ± 71.6 minutes as compared with 403.5 ± 89.7 minutes for im administration. However, the im route produced longer detectable plasma concentrations (50 hours in 2 of the 4 horses). Based on bacterial sensitivity information derived for human and canine isolates, the daily oral administration of 10 mg of rifampin/kg administered in the feed represents a reasonable dose for susceptible gram-positive bacterial pathogens. Higher doses (≥ 25 mg/kg) or iv administration would be required for most gram-negative bacteria. Adverse effects of sufficient severity to limit use of the drug, especially by the oral route of administration, were not encountered under the single-dose experimental conditions used.
Cell-mediated and humoral immune response to Mycoplasma hyopneumoniae in pigs enhanced by dextran sulfate
Authors: Kishima M. , Ross R. F. , Kuniyasu C.
Published: February 2025

The effect of dextran sulfate (ds), known to be cytotoxic to macrophages, on the cell-mediated and humoral immune response to nonviable Mycoplasma hyopneumoniae in pigs was investigated. The cell-mediated immune response was determined by means of lymphocyte transformation a test, using uptake of [3H]thymidine in a microculture system and the humoral immune response by means of a microplate complement-fixation test. Peripheral blood lymphocytes from pigs vaccinated with nonviable M hyopneumoniae and ds incorporated substantially more [3H]thymidine than did those from pigs given Mycoplasma or ds alone. The transformation of lymphocytes from M hyopneumoniae-ds vaccinated pigs was enhanced when M hyopneumoniae cells used in the assay system were heated at 60 C for 30 minutes. Similarly prepared M flocculare and M hyorhinis cells also stimulated lymphocytes from M hyopneumoniae-ds vaccinated pigs, but not nearly as great as when M hyopneumoniae cells were used. The humoral antibody response and the cell-mediated immune response to nonviable M hyopneumoniae was markedly enhanced by ds. Pigs were vaccinated with nonviable M hyopneumoniae and/or ds 4 times and challenge exposed intratracheally with viable M hyopneumoniae. Pigs vaccinated with M hyopneumoniae and ds had less severe pneumonia than did nonvaccinated pigs.
Pharmacokinetics of digoxin in sheep: Limitations of the use of biological half-life for interspecies extrapolation
Authors: Dix L. P. , Bai S. A. , Rogers R. A. , Anderson D. L. , Riviere J. E.
Published: February 2025

After of single iv digoxin injection of 50 μg/kg of body weight, the serum digoxin concentrations of 4 sheep were fitted to a 2-compartment open model. The mean value for the elimination half-life was 7.15 hours; for area volume of distribution, 13.8 L/kg; and for total body clearance, 1.36 L/kg/hr. A comparison of this study with previous studies in sheep and cattle revealed that serious misconceptions could arise if one chose to rely upon elimination half-life as the sole descriptor of drug disposition. A more informative characterization was determined to be total body clearance and area volume of distribution.
Effect of washing on motility and acrosome morphology of frozen-thawed goat spermatozoa
Authors: Memon Mushtaq A. , Bretzlaff Katherine N. , Ott Randall S.
Published: February 2025

Semen from 4 bucks was collected using an artificial vagina and was pooled and divided into 6 aliquots. Three aliquots were washed twice, 15 minutes each time, with Ringer's solution, and the fluid was removed by centrifugation at 950 × g between washes. All 6 aliquots (3 washed and 3 unwashed) were extended with skim milk-glycerol, lactose-egg yolk-glycerol, or tris (hydroxymethyl) aminomethane-citric acid-egg yolk-glycerol and were frozen in straws to −196 C. The semen was then thawed and kept at 37 C for 8 hours. Percentage of sperm motility was estimated, and the percentage of normal acrosomes (na) was determined at 0, 2, 4, 6, and 8 hours after thawing. The experiment was repeated 7 times. The data indicated a significant positive effect (P = 0.0009) of washing on motility, but no effect (P = 0.5347) of extender. There was also a significantly higher percentage of na in washed semen (P < 0.0001). Sperm extended in tris aminomethane-citric acid-egg yolk-glycerol had more na than those extended in lactose-egg yolk-glycerol. Sperm motility and acrosome morphology were depressed also in the presence of seminal plasma for the milk extender, which did not contain egg yolk. Removal of seminal plasma from goat semen was beneficial in preserving the integrity of the spermatozoa after freezing, regardless of the extender used.
Effect of a once-daily suckling program on gastrointestinal parasitism in Angus cows and calves
Authors: Ciordia H. , Stuedemann J. A. , Wilkinson S. R. , McCampbell H. C. , Caudle A. B. , Ernst J. V.
Published: February 2025

Over a 2-year period involving a total of 168 Angus cows and their calves, 2 studies were conducted to evaluate the effect of once-daily suckling on cow reproduction, calf growth, and gastrointestinal parasitism. Experiment I compared 2 restricted suckling (rs) groups with 1 normal suckling (ns) group. Each group consisted of 24 cows with their calves (24 cows-calves/group = 24 cows and 24 calves/group). In the rs groups, suckling by the calves was restricted to once a day for 45 days, and then the calves were allowed to suckle normally throughout the remainder of the experiment. In the ns group, the calves suckled normally throughout the experiment. Experiment II compared 2 groups of rs cow-calves (24 cow-calves/group) with 2 groups of 24 ns cow-calves/group.

In experiment I, there were ne differences (P < 0.05) in pregnancy rate or in the average number of nematode eggs/g of feces (epg) between the cows from the 2 treatment groups. The rs calves consistently had higher epg counts than did the ns calves during the 45 days of rs (169 vs 62 epg, P < 0.05) and from the time of their return to pasture until weaning (266 vs 186 epg, P = 0.27). The rs calves also had a higher average coccidia oocyst count during the rs period only. In experiment II, rs cows had a higher pregnancy rate (87.6% vs 66.0%, P < 0.05) and a shorter postpartum interval (83 vs 101 days, P < 0.05) than did ns cows. There was no difference in epg from cows, but the rs calves had higher epg during the rs period (160 vs 115, P = 0.19) and during the pasture period (329 vs 154, P < 0.05) than did the ns calves. In both experiments, ns calves had higher (P < 0.05) adjusted 205-day weights and actual weaning weights than did the rs calves. In experiment I, adjusted 205-day weights for the ns and rs calves were 160.1 and 129.0 kg, respectively. In experiment II, adjusted 205-day weights for ns and rs calves were 148.7 and 121.9 kg, respectively. Under the conditions of the present study, the rs technique improved conception rates in young cows, but resulted in lighter calves with a higher degree of internal parasitism.
Bovine anaplasmosis: Transplacental transmission as it relates to stage of gestation
Authors: Zaugg J. L.
Published: February 2025

Six mature, pregnant, anaplasmosis-susceptible and 3 anaplasmosis-carrier beef cows were used in Anaplasma in utero transmission studies. Susceptible cows were randomly allotted into 3 groups of 2 cows each and were inoculated with a Virginia A marginale stabilate. Each group was Anaplasma-exposed once during 1 of the 3 trimesters of pregnancy. Blood samples were obtained from each fetus at various stages of development for evaluation and for subinoculation into splenectomized calves once during gestation. Precolostral blood from neonates was also subinoculated into individual susceptible calves.

Two of the 9 splenectomized calves given fetal blood inoculations developed acute anaplasmosis. The dam of 1 fetus with infective blood was Anaplasma-exposed during the 2nd trimester of pregnancy, and the dam of the second fetus was exposed during her 3rd trimester. Infective fetal blood was obtained during the same trimester of gestation in which the dams were inoculated. Calves given neonatal precolostral blood did not develop anaplasmosis.
Demonstration of vaccine-induced immunity to anaplasmosis without induction of persistent postvaccinal complement-fixing and agglutinating antibodies in yearling steers
Authors: Corrier Donald E. , Johnson Janice S. , Wagner Gerald G.
Published: February 2025

The protective effect and anti-Anaplasma complement-fixing and agglutinating antibody responses induced in yearling steers by vaccination with an inactivated Anaplasma marginale vaccine were evaluated by challenge exposure. Eleven 12- to 14-month-old Hereford × Angus steers were randomly allotted into 6 principals and 5 controls. The principals were injected im with 5 ml of vaccine on days 0 and 21. On day 70, the 11 steers were challenge exposed by iv inoculation of A marginale-infected blood.

After a prolonged prepatent period, the vaccinated steers developed a significantly (P < 0.01) lower A marginale parasitemia (8.0%) than did the nonvaccinated controls (26.3%). The persistence of a ≥ 0.5% parasitemia was significantly (P < 0.025) reduced from 34 days in the control to 21 days in the vaccinated group. The percentage reduction in pcv was significantly (P < 0.025) less in the vaccinated group (34%) as compared with the controls (57%). Complement-fixing and agglutinating antibody responses induced by vaccination did not persist for more than 21 days after the 2nd vaccine injection and did not interfere with positive seroconversion resulting from challenge exposure.
Arterial to end-tidal CO2 tension and alveolar dead space in halothane- or isoflurane-anesthetized ponies
Authors: Meyer Robert E. , Short Charles E.
Published: February 2025

SUMMARY AND CONCLUSIONS

The correlation between end-tidal partial pressure of CO2 (PetCO2) and arterial (PaCO2) was determined for spontaneously breathing ponies under halothane or isoflurane anesthesia. The PetCO2 was useful as a trend indicator of PaCO2 during the first 60 minutes of halothane or isoflurane anesthesia when PaCO2 values were < 60 to 70 mm of Hg. Halothane anesthesia lasting > 90 minutes was associated with PaCO2 values in excess of 60 to 70 mm of Hg, a large arterial- to end-tidal PCO2 difference (PaCO2-PetCO2) and a significant increase in alveolar dead space. These effects were not seen during the same period of isoflurane anesthesia. Arterial blood gas analysis is therefore recommended during halothane anesthesia when the PetCO2 is > 60 to 70 mm of Hg. A decrease in alveolar capillary perfusion relative to alveolar ventilation is the most likely cause for the increase in alveolar dead space during halothane anesthesia. Based on these findings, isoflurane may be superior to halothane for prolonged anesthesia of spontaneously breathing horses.
Direct current stimulation of bone production in the pony: Observations with a diaphyseal osteotomy model
Authors: Collier M. A. , Brighton C. T. , Rendano V. T. , Schryver H. F. , Kallfelz F. A.
Published: February 2025

Electrically induced osteogenesis exhibits a dose response curve and can induce bone formation in the absence of trauma and in nonunions. Electrically induced osteogenesis, using direct electric current (dc) in a third metacarpal diaphyseal osteotomy model, in conjunction with internal fixation and postoperative loading, was investigated. Twelve young adult ponies of mixed sex were divided into 2 treatment groups (A and B) of 3 stimulated and 3 controls each and evaluated, using a specifically designed procedure. Stimulated ponies in both groups were given 20 μA of dc via an implanted bone growth stimulator (bgs); group A ponies were stimulated for 60 days and group B ponies for 120 days. Biocompatibility of the bgs was excellent in all ponies. Radiographically, there was more advanced healing with better vascular development in the ponies stimulated for 60 days compared with controls, but no discernible difference was seen at 120 days. Nuclear medical bone imaging revealed a peak uptake at 4 weeks in stimulated groups and the uptake decreased after 8 weeks. Radiopharmaceutical uptake in stimulated ponies was consistently below control uptake throughout the study. Mean specific gravity (sg) of specimens prepared for testing materials properties for group A and B controls were 2.044 ± 0.119 and 1.939 ± 0.065, respectively. The sg for group A and group B stimulated were 1.992 ± 0.049 and 1.876 ± 0.031, respectively. The sg of specimens obtained from metacarpi of age-matched control ponies was 2.194 ± 0.166. The ultimate bending strengths and the flexural moduli of elasticity in 60-day control ponies and stimulated ponies were 57 ± 8.4, 59 ± 23.9 MN/m2 and 89 ± 3.5, 106 ± 6.5 MN/m2 and in 120-day control ponies and stimulated ponies were 13 ± 1.0, 13 ± 3.2 GN/m2 and 13 ± 2.89, 15 ± 0.577 GN/m2, respectively. Sixty-day samples and 120-day samples had ultimate bending strengths (su) of 25% and 50% that of unfractured cortex, respectively. These findings indicate that 20 μA of dc stimulation on a diaphyseal osteotomy model may not stimulate sufficient bone production to affect the mechanical properties of the bone. Therefore, based on our research, clinical use of bgs in fresh fracture management cannot be recommended.