bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructure and mineral composition of urinary calculi from horses
Authors: Neumann Rebecca D. , Ruby Annette L. , Ling Gerald V. , Schiffman Peter , Johnson Deedra L.
Published: January 2024

Urinary calculi from 17 horses with urolithiasis were examined to study their mineral content and ultrastructure. Among the analytic methods used were X-ray diffractometry, scanning electron microscopy, and electron microprobe analysis.

The calculi initially were observed by use of a stereoscopic dissecting microscope and generally were found to have nodular surfaces surrounding a banded or granular-to-chalky interior. Observation by scanning electron microscopy revealed an intricate pattern of irregularly concentric, fine bands and spherules. These had a round, finely banded, globular texture formed by precipitation of ultrafine-grained radiating crystals. The original pore spaces (ie, between spherules, between bands and spherules, or between crystal generations) could be observed as primary porosity. Precipitation and dissolution of these urinary calculi were observed to be spontaneous processes, which can occur simultaneously within an individual calculus. Another prominent feature of the ultrastructure was secondary porosity (spontaneous dissolution) which, in its incipient stages, appeared to be site-selective (ie, some bands appeared to be more susceptible to development of pinpoint porosity). Textures indicative of dissolution were observed not only on the calculus surface, but within the calculus interior as well. Areas that had more advanced stages of dissolution, resulting in increased secondary porosity, also were observed.

All 17 samples of the study were found to be composed of calcium carbonate in the form of the mineral calcite, although minor quantities of 2 other polymorphs of calcium carbonate, minerals vaterite and aragonite, also were encountered. Vaterite was observed in 5 of the samples, whereas aragonite was found in 1 sample.

Strontium and sulfur were observed as trace elements in 3 of the calculi, whereas magnesium was present in all calculi. Magnesium was observed to substitute for calcium within the calcite crystal lattice in larger quantities than those of strontium or sulfur. Magnesium Kα X-ray dot maps generated by use of an electron microprobe analyzer indicated that the distribution pattern of magnesium appeared to closely follow layer-by-layer growth of the calculus. Magnesium distribution also appeared to be related to porosity development. In samples where preferential dissolution was observed, the more porous areas had higher magnesium content. Quantitative chemical analyses, using the electron microprobe analyzer, confirmed these observations.

Association of the magnesium distribution pattern to the primary growth texture of the calculus indicated that magnesium content of the calculus varied during the formation process. This also indicated that changes in urine chemical analytes may be reflected in composition of the calculi formed. High magnesium content in areas that had preferential dissolution further indicated that susceptibility to dissolution increases with increasing magnesium content.
Reduction of the prevalence of pseudorabies virus-infected breeding pigs by use of intensive regional vaccination
Authors: Stegeman Arjan , Van Oirschot Jan T. , Kimman Tjeerd G. , Helen Martin J. M. , Hunneman Wil A. , Bemdsen Frans W.
Published: January 2024

The influence of an intensive vaccination program on prevalence of pseudorabies virus (prv)-infected breeding pigs was examined in a region where the disease was enzootic. In a 2-year period, significantly (P < 0.005) greater decrease in the prevalence of prv-infected breeding pigs was observed in herds participating in the regional vaccination program and in herds outside the trial region that intensified prv vaccination during the study than in herds that applied routine prv control measures. In the regional vaccination program, introduction of breeding stock from outside the area was significantly (P < 0.05) associated with higher prevalence of prv-infected pigs at the end of the study. These results indicate that transmission of prvcan be markedly reduced by use of an accurately applied intensive vaccination program.
In vitro susceptibility of equine Salmonella strains to trimethoprim and sulfonamide alone or in combination
Authors: van Duijkeren Engeline , van Klingeren B. , Vulto A. G. , van Oldruiteriborgh-Oosterbaan Marianne M. Sloet , Breukink H. J. , van Miert A. S. J. P. A. M.
Published: January 2024

The in vitro activity of trimethoprim (tmp) and 9 sulfonamides and their combinations in 6 concentration ratios was tested against 62 Salmonella strains isolated from horses over a 3-year period in the Netherlands, using the agar-dilution method. Most of the isolates were S typhimurium strains (n = 52); the others were S heidelberg (n = 3), S hadar (n = 2), S thompson (n = 2), S enteritidis (n = 1), S infantis (n = 1), and S derby (n = 1). The minimal TMP concentration at which 50% of the Salmonella strains were inhibited (mic50) was 0.12 |ig/ml. Sulfachlorpyridazine (scp; mic50, 16 fig/ml), sulfamethoxazole (smx; mic50, 32 μg/ml), and sulfadiazine (sdz; mic50; 32 μg/ ml) were the most potent of the sulfonamides tested. The antimicrobial effect of the sulfonamides, in combination with tmp (additive, synergistic, or antagonistic), was expressed by the fractional inhibitory concentration (fic) index. Concentrations of sdz and scp with tmp had marked synergism at all tested tmp-to-sulfonamide concentration ratios (1:1 to 1: 160; fic index, 0.10 to 0.50); smx had synergy with tmp at all ratios, except 1:1 (fic index, 0.10 to 0.27). Sulfamethazine, sulfamerazine, sulfadoxine (sdx), sulfatroxazole, sulfadimethoxine, and sulfacetamide had mic50 greater than their breakpoint mic value and are, therefore, less potent drugs. However, synergy with TMP was found for these less potent sulfonamides at certain concentration ratios, depending on the sulfonamide used. Sixteen Salmonella strains were resistant to tmp, all sulfonamides, and tmp-sulfonamide combinations; 14 of these strains were S typhimurium phage type 200, 1 was S typhimurium phage type 61, and 1 was S typhimurium phage type 10. Four additional Salmonella strains were resistant to the sulfonamides alone (1 S typhimurium phage type 171 and 3 S typhimurium strains that could not be biotyped). Results of this study indicate that sdz, scp, and smx are the best sulfonamides to combine with tmp for treatment of salmonellosis in equids, because they are the most potent sulfonamides and have strong synergism with tmp at a wide range of tmp-to-sulfonamide concentration ratios.
Neutrophil accumulation in the large colon of horses during low-flow ischemia and reperfusion
Authors: Moore Rustin M. , Bertone Alicia L. , Bailey Michael Q. , Muir William W. , Beard Warren L.
Published: January 2024

Histomorphologic/morphometric evaluation, leukocyte scintigraphy, and myeloperoxidase activity were used to determine whether neutrophils accumulate in the large colon of horses during low-flow ischemia and reperfusion. Twenty-four adult horses were assigned to 1 of 3 groups: group 1, sham-operated (n = 6); group 2, 6 hours of ischemia (n = 9); and group 3, 3 hours of ischemia and 3 hours of reperfusion (n = 9). Low-flow ischemia of the large colon was induced in horses of groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline. Radiolabeled (99mTc) autogenous neutrophils were injected at 175 minutes, which corresponded to 5 minutes prior to reperfusion in group-3 horses. Full-thickness biopsy specimens of the left ventral colon were collected at baseline and at 30-minute intervals for 6 hours; a portion of the biopsy specimen was placed in formalin for histologic examination, and the remainder was used to measure mucosal radioactivity and myeloperoxidase activity. There were no differences in baseline mucosal neutrophil index, mucosal neutrophil numbers, submucosal venular neutrophil numbers, mucosal radioactivity, or mucosal myeloperoxidase activity among groups, or over time in group-1 horses. Neutrophils accumulated in the colonic mucosa during ischemia and further increased at reperfusion, as indicated by neutrophil index (morphology) and mucosal neutrophil numbers (morphometry); mucosal neutrophil index was significantly (P < 0.05) greater in group-3 horses during reperfusion than at the corresponding periods of ischemia in group-2 horses. Neutrophil numbers were significantly (P < 0.05) increased in submucosal venules at 10 minutes of reperfusion in group-3 horses and were significantly (P < 0.05) greater in group-3 than in group-2 horses during the interval from 3 to 6 hours. Mucosal radioactivity significantly (P < 0.05) increased at reperfusion in group-3 horses; there was a trend (P = 0.076) toward greater mucosal radioactivity in group-3, compared with group-2 horses, throughout the 3- to 6-hour interval. There were no differences in mucosal myeloperoxidase activity among or within any of the 3 groups over time.

Neutrophils accumulated in the large colon of horses during low-flow ischemia and reperfusion. Neutrophil infiltration was detected by histologic examination and leukocyte scintigraphy, but not by measurement of myeloperoxidase activity. The accumulation of neutrophils during ischemia and the further neutrophil infiltration during reperfusion indicate that neutrophils may contribute to reperfusion injury of the large colon.
Consideration of anatomic and radiographic features of the caudal pouches of the femorotibial joints of horses for the purpose of arthroscopy
Authors: Trumble Troy N. , Stick John A. , Arnoczky Steven P. , Rosenstein Diana
Published: January 2024

Development of an arthroscopic approach to the caudal pouches of the equine stifle has been necessary because cranial approaches do not allow access to articular lesions in the caudal aspect of the joint. Therefore, the anatomy of the caudal region was examined in 52 cadaver limbs by use of gross dissection (29), x-ray-computed tomography (6), fluoroscopy (8), or arthroscopy (9). Additionally, using arthroscopic techniques developed in equine cadaver limbs, 3 stifles from 2 anesthetized horses were arthroscopically explored. Fluoroscopy was used to verify needle placement for joint injection and filling patterns of each femorotibial joint. The medial femorotibial joint sac (n = 4) held a mean ± sd 41.67 ± 5.77 ml of injection fluid, and the lateral femorotibial joint sac (n = 4) held a mean 61.67 ± 2.89 ml of injection fluid. Vital structures that inadvertently could be damaged during arthroscopy of the caudal pouches of the stifle included the peroneal nerve (located approx 7 cm caudal to the lateral collateral ligament), the popliteal artery and vein (situated directly between the medial and lateral femoral condyles), and the lateral femoral condyle (most often traumatized during arthroscopy). The tendon of the popliteus muscle, which is contiguous with the joint capsule of the caudal pouch of the lateral femorotibial joint, made arthroscopic exploration of this pouch particularly difficult.
Administration of ochratoxin A and T-2 toxin to growing swine
Authors: Harvey Roger B. , Kubena Leon F. , Elissalde Marcel H. , Rottinghaus George E. , Corrier Donald E.
Published: January 2024

Effects of dietary ochratoxin A (oa) and T-2 toxin, fed singly and in combination, were evaluated in growing crossbred pigs. Thirty-six barrows (3 replicates of 3 for each of 4 treatment groups, mean body weight, 18.0 kg) were fed: 0 mg of oa and 0 mg of T-2/kg of feed (control); 2.5 mg of oa/kg of feed; 8.0 mg of T-2/kg of feed; or 2.5 mg of oa plus 8.0 mg of T-2/kg of feed for 30 days. Production performance, serum biochemical, hematologic, immunologic, and pathologic evaluations were made. Body weight and body weight gain were decreased by all toxin treatments, but the combination toxin treatment reduced weight gain more than did either of the toxins administered singly and could be considered additive. Liver weight was decreased by combination treatment, whereas kidney weight was increased by oa treatment. Ochratoxin decreased serum cholesterol, inorganic phosphorus, and alkaline phosphatase values; reduced mean cell volume, hemoglobin concentration, and macrophage phagocytosis; and increased creatinine and total protein values. Consumption of T-2 toxin reduced hemoglobin and serum alkaline phosphatase values. The combination treatment decreased serum cholesterol, γ-glutamyltransferase, alkaline phosphatase, mean cell volume, hematocrit, and hemoglobin values, as well as lymphoblastogenesis and phagocytosis, and increased serum creatinine concentration. We concluded that oa and T-2, singly or in combination, can affect clinical performance, serum biochemical, hematologic, and immunologic values, and organ weights of growing barrows. Although some analytes were affected more by the combination than by either toxin alone, the interactions could best be described as additive, not synergistic.
Efficacy of 4-methylpyrazole for treatment of ethylene glycol intoxication in dogs
Authors: Dial Sharon M. , Thrall Mary Anna Hull , Hamar Dwayne W.
Published: January 2024

4-Methylpyrazole (4-mp), an alcohol dehydrogenase inhibitor, was administered to dogs to treat ethylene glycol (eg) intoxication. Eleven dogs were given 10.6 g of eg/kg of body weight; 5 dogs were treated with 4-mp 5 hours after eg ingestion and 6 dogs were treated with 4-mp 8 hours after eg ingestion. 4-Methylpyrazole was administered iv as a 50-mg/dl solution in 50% polyethylene glycol: initial dose, 20 mg/kg; at 12 hours after initial dose, 15 mg/kg; at 24 hours after initial dose, 10 mg/kg; and at 30 hours after initial dose, 5 mg/kg. Physical, biochemical, hematologic, blood gas, serum and urine eg concentrations, and urinalysis findings were evaluated at 0, 1, 3, 6, 9, 12, 24, 48, 72 hours, and at 1 week and 2 weeks after eg ingestion.

Dogs of both groups developed clinicopathologic signs associated with eg intoxication, including cns depression, hyperosmolality, high anion gap metabolic acidosis, polydipsia, polyuria, calcium oxalate monohydrate and dihydrate crystalluria, and isosthenuria. Fractional excretion of sodium was increased in all dogs between 1 and 9 hours after eg ingestion, but remained increased beyond 24 hours only in the 2 dogs treated at 8 hours after eg ingestion that developed acute renal failure. All dogs treated 5 hours after eg ingestion recovered without morphologic, biochemical, or clinical evidence of renal impairment. Of the 6 dogs treated 8 hours after eg ingestion, 2 developed acute renal failure. One of the dogs treated 8 hours after eg ingestion remained isosthenuric for 2 months, but did not manifest any other signs of renal impairment. Of the dogs treated 8 hours after eg ingestion, 3 recovered without morphologic, biochemical, or clinical evidence of renal impairment. Serum half-life of eg was prolonged in the dogs treated 8 hours after eg ingestion. Percentage of eg excreted unchanged was 84 ± 2% in the dogs treated 5 hours after eg ingestion, and was 40 ± 10% in the dogs treated 8 hours after eg ingestion. 4-Methylpyrazole was effective in preventing renal failure in all dogs given 10.6 g of eg/kg when treatment was initiated by 5 hours after eg ingestion, and in 4 of 6 dogs when treatment was initiated by 8 hours after eg ingestion.
Effect of food deprivation on baseline iodothyronine and cortisol concentrations in healthy, adult horses
Authors: Messer Nathaniel T. , Johnson Philip J. , Refsal Kent R. , Nachreiner R F. , Ganjam V. K. , Krause G. F.
Published: January 2024

Six healthy, adult horses, with normal (mean ± sem) baseline serum concentrations of total triiodothyronine (T3,1.02 ± 0.16 nmol/L), free T3 (FT3,2.05 ± 0.33 pmol/L), total thyroxine (T4, 19.87 ± 1.74 nmol/L), free T4 (FT4, 11.55 ± 0.70 pmol/L), total reverse T3 (rT3, 0.68 ± 0.06 nmol/L), and cortisol (152.75 ± 17.50 nmol/L), were judged to be euthyroid on the basis of response to a standardized thyroid-stimulating hormone response test. Serum concentrations of T3, FT3, T4, FT4, rT3, and cortisol were determined immediately before and every 24 hours during a 4-day period of food deprivation, when water was available ad libitum. Similar variables were measured 72 hours after refeeding.

Decreases (to percentage of baseline, prefood deprivation value) in circulating T3 (42%), T4 (38%), FT3 (30%), and FT4 (24%) concentrations were maximal after 2, 4, 2, and 4 days of food deprivation, respectively (P < 0.05). Increases (compared with baseline, prefood deprivation value) in rT3 (31%) and cortisol (41%) concentrations were maximal after 1 and 2 days of food deprivation, respectively (P < 0.05). Refeeding resulted in increase in serum T4 and FT4, and decrease in rT3 and cortisol concentrations toward baseline values, after 72 hours (P < 0.05). Re-feeding did not effect a return of T3 or FT3 concentration to baseline values after 72 hours (P < 0.05).

Food deprivation appears to cause changes in serum concentrations of T3, FT3, T4, FT4, rT3, and cortisol in horses that are similar to those in human beings. This effect of food deprivation should be considered when results of serum thyroid hormone and cortisol assays are interpreted in the face of clinical disease. These results further emphasize the invalidity of making a clinical diagnosis of hypothyroidism on the basis of baseline, serum thyroid hormone concentrations in horses, especially if the horses have been anorectic or inappetent.
Determination of carbonic anhydrase III isoenzyme concentration in sera of racehorses with exertional rhabdomyolysis
Authors: Nishita Toshiho , Ohohashi Takahiro , Asari Masao
Published: January 2024

The concentration of carbonic anhydrase III isoenzyme (ca-III) in serum samples from 216 clinically normal Thoroughbreds was determined by use of an enzyme immunoassay. The concentration range of ca-III was from 16.0 to 254.5 ng/ml (mean, 56.5 ± 11.9 ng/ml). Significant differences were not detected according to age or sex. To confirm whether serum ca-III concentration was high in horses with muscle disease, serum samples of 11 horses with exertional rhabdomyolysis were analyzed by enzyme immunoassay. Their serum ca-III concentration was about 56 times (3,136 ± 2,610 ng/ml) that of healthy Thoroughbreds. Concentration of ca-III was higher in horses with rhabdomyolysis that had been transiently recumbent than in horses with mild disease that were reluctant to move. Blood samples obtained serially from 6 horses with exertional rhabdomyolysis were studied. Serum activities of aldolase, creatine kinase, aspartate transaminase, and lactate dehydrogenase were high. Increases and decreases in concentration of ca-III were more rapid than that for aldolase, creatine kinase, aspartate transaminase, and lactate dehydrogenase activities; thus, ca-III may be clinically applicable as a diagnostic marker for muscle disease in horses.
Characterization of functions of neutrophils from bone marrow of cattle with leukocyte adhesion deficiency
Authors: Nagahata Hajime , Nochi Hiromi , Tamoto Koichi , Yamashita Kazuto , Noda Hiroshi , Kociba Gary J.
Published: January 2024

Marked differences in bone marrow cellularity were observed between cattle affected with leukocyte adhesion deficiency (lad) and control cattle. The number of nucleated cells in bone marrow was 2.9 to 8.8 times higher in cattle affected with lad, compared with controls. The myeloid-to-erythroid ratio of bone marrow from 3 cattle affected with lad ranged from 2.4 to 12. Deficient CD18 expression on neutrophils isolated from bone marrow of cattle with lad was clearly detected by flow cytometric analysis. Neutrophils from bone marrow of cattle affected with lad appeared round and not flat, after adherence to plastic wells under agarose, whereas neutrophils from bone marrow of clinically normal cattle were firmly spread on the surface of plastic wells. In the chemotaxis under-agarose assay, many pseudopodia were detected on bone marrow neutrophils from clinically normal cattle, but were not detected on bone marrow neutrophils from cattle with lad. Activities of chemotactic movements and phagocytosis of neutrophils isolated from bone marrow of cattle affected with lad were documented to be severely impaired.
Effects of vitamin E on immune function of dairy cows
Authors: Politis I. , Hidiroglou M. , Batra T. R. , Gilmore J. A. , Gorewit R. C. , Scherf H.
Published: January 2024

The effect of vitamin E supplementation on the immune function of dairy cows was studied. Twelve cows were assigned to 1 of the 2 experimental groups: control (no vitamin E supplementation), and vitamin E-supplemented. Supplementation of vitamin E started 4 weeks before and continued up to 8 weeks after parturition and included oral supplementation of vitamin E at the rate of 3,000 IU/cow/d. In addition, the same group of cows received 1 injection of vitamin E (5,000 IU), 1 week prior to the expected date of parturition. Data indicated that blood neutrophils isolated from control cows produced twofold less (P < 0.05) superoxide anion after parturition, compared with the corresponding value before parturition. Furthermore, blood macrophages isolated from control cows produced 15 and 35% (P < 0.05) less interleukin 1 (il-1) and major histocompatibility (mhc) class-II antigens, respectively, after parturition, compared with the corresponding values before parturition. These data, collectively, indicate that functions of blood macrophages and neutrophils are depressed during the early postpartum period in control cows. In contrast, there were no differences in superoxide anion production by blood neutrophils, or in il-1 production, and mhc class-II antigen expression by blood macrophages before and after parturition in cows supplemented with vitamin E. There were no differences in lymphocyte proliferation, or il-1 production and mhc class-II antigen expression by mammary macrophages when control and vitamin E-supplemented cows were compared. We conclude that vitamin E prevented suppression of blood neutrophil and macrophage function during the early postpartum period.
Effects of medetomidine administration on intracranial pressure and cardiovascular variables of isoflurane-anesthetized dogs
Authors: Keegan Robert D. , Greene Stephen A. , Bagley Rodney S. , Moore Michael P. , Weil Ann B. , Short Charles E.
Published: January 2024

Intracranial pressure and cardiovascular variables after iv administration of medetomidine (0.03 mg/kg of body weight) were evaluated in 6 healthy, mixed-breed dogs anesthetized with 1.3% end-tidal isoflurane concentration and mechanically ventilated to normocapnia (PaCO2, 35 to 45 mm of Hg). Baseline values were determined for intracranial pressure, heart rate, arterial blood pressure, cardiac output, mean pulmonary artery pressure, pulmonary capillary wedge pressure, central venous pressure, end-tidal CO2 tension and isoflurane concentration, arterial pH and CO2 and O2 tensions, and core body temperature. Cerebral perfusion pressure, cardiac index, systemic and pulmonary vascular resistances, plasma HCO3- concentration, and base excess were calculated. Intracranial pressure was measured, using a calibrated, fiberoptic transducer placed within the brain parenchyma and secured to the calvarium by means of a subarachnoid bolt. Cardiac output was determined by thermodilution. End-tidal CO2 tension and isoflurane concentration were determined, using an infrared gas analyzer. Administration of medetomidine did not change intracranial pressure, but was associated with significant (P < 0.05) decreases in values for heart rate, cardiac index, end-tidal CO2, and HCO3- and with significant increases in systolic, mean, and diastolic pressure; pulmonary artery pressure; systemic vascular resistance; central venous pressure; and pulmonary capillary wedge pressure.
Quantitative electroencephalographic evaluation to determine the quality of analgesia during anesthesia of horses for arthroscopic surgery
Authors: Miller Susan M. , Short Charles E. , Ekström Peter M.
Published: January 2024

We compared the anesthetic combination of detomidine, ketamine, and halothane in control horses not undergoing apparently painful procedures with that in horses during arthroscopic surgery. The effectiveness of this regimen in suppressing neurologic response to surgery was, thus, evaluated. In this study, significant differences were not observed in electroencephalographic total amplitude, spectral edge, or beta-to-delta frequency ratio between surgically treated and nonsurgically treated (control) horses. On the basis of its attenuation of encephalographic responses, we conclude that detomidine (20 μg/kg of body weight, iv) and ketamine (2.2 mg/kg, iv) induction of anesthesia followed by maintenance with halothane is an effective regimen for control of pain in horses during arthroscopic surgery.

The insignificant frequency changes observed without any other signs of inadequate anesthesia or pain may indicate a surgical stress response. We hypothesize that brain activity monitoring may give an earlier index to initiation of surgically induced stress than do hormonal responses, because endocrine alterations are not as rapidly perceived as is the electroencephalogram. Analysis of spectral edge frequency changes could be used to evaluate anesthetic regimens to find those that cause the least stress to the cns during surgery in horses. Differences in species responses to an anesthetic agent or the regimen’s effectiveness in prevention of pain during surgery may be identified by adoption of the study model. Evaluation of cardiopulmonary variables during anesthesia, with and without surgery, did not reveal any alterations that would be relevant to cns responses. Blood pressure, heart rate, , , and pH were stabilized by use of intermittent positive-pressure ventilation in all horses, and dobutamine was administered, as needed, to avoid bias of electroencephalogram data.
Risk of feline infectious peritonitis in cats naturally infected with feline coronavirus
Authors: Addie Diane D. , Toth Sarah , Murray Gordon D. , Jarrett Oswald
Published: January 2024

A longitudinal survey of 820 cats in 73 households was conducted over a period of 6 years to establish the fate of pet cats that were seropositive after natural exposure to feline coronavirus (FCoV). In particular, their risk of developing feline infectious peritonitis (fip) was determined. The seropositive cats were assigned to 1 of 3 groups: cats from households in which fip had recently been diagnosed; cats from households in which fip had not been diagnosed, but from which kittens had been relocated and subsequently died of fip; and cats from households in which fip had not been diagnosed. Cats in the first group were not at greater risk of developing fip than were cats in the other 2 groups. Consequently, any household in which seropositive cats live must be considered a potential source of FCoV that can cause fip. There was no evidence that the enhanced disease, which has been described after experimentally induced infection of seropositive cats, exists in nature. Thus, analysis of the survival of the seropositive cats over periods of up to 36 months indicated that their risk of developing fip decreased with time, suggesting the development of immunity rather than increased susceptibility to disease. In addition, of 56 cats deemed to have been naturally reinfected because their anti- FCoV antibody titers decreased and subsequently increased, only 3 developed fip.
Detection of bovine immunodeficiency virus in blood and milk-derived leukocytes by use of polymerase chain reaction
Authors: Nash Jerry W. , Hanson Larry A. , Coats Karen St. Cyr
Published: January 2024

Bovine immunodeficiency virus (biv) is prevalent in beef and dairy cattle, yet the mode(s) of biv transmission are undefined. Using polymerase chain reaction, which specifically targeted a 235-bp, highly conserved region of the biv pol gene, biv-infected leukocytes were detected in the blood and milk of biv- seropositive cows. These data confirm the presence of biv in milk and identify the potential for lactogenic transmission of this vims.
Comparative treatment of mares susceptible to chronic uterine infection
Authors: Troedsson Mats H.T. , Scott Mary A. , Liu Irwin K.M.
Published: January 2024

Four intrauterine treatment strategies were evaluated for effectiveness in mares that were confirmed to be susceptible to chronic uterine infection. Pretreatment samples were obtained at detection of estrus, and a genital strain of Streptococcus zooepidemicus was infused into the uterus when a preovulatory (> 35 mm) follicle was detected. At 12 hours after inoculation, mares were assigned to 1 of 4 selected treatment groups: autologous plasma, 100 ml (n = 5); potassium penicillin, 5 million U in 100 ml of phosphate-buffered saline solution (pbss; n = 5); 10 mg of prostaglandin F2α in 100 ml of pbss (n = 5); and large-volume lavage with normal saline solution (1,000 ml increments). A fifth group, treated with vehicle alone (100 ml of pbss), served as a negative control (n = 7). All treatments were administered into the uterus. To assess the effectiveness of the treatment, samples for culture and cytologic examination were collected at 96 hours after bacterial inoculation. An effect of treatment was observed on the number of uterine neutrophils (P = 0.02) and growth of S zooepidemicus (P < 0.01). Intrauterine treatment with potassium penicillin, prostaglandin F2α, and largevolume uterine lavage significantly reduced the growth of S zooepidemicus (P < 0.01) as well as the number of neutrophils (P < 0.02). Autologous plasma reduced the number of neutrophils (P < 0.05), but not growth of S zooepidemicus. There was significant correlation between the number of uterine neutrophils and growth of S zooepidemicus for each treatment group (r = 0.57; P < 0.05).
Ceftiofur distribution in serum and milk from clinically normal cows and cows with experimental Escherichia coli-induced mastitis
Authors: Erskine R. J. , Wilson Robert C. , Tyler Jeff W. , McClure Kim A. , Nelson Renee S. , Spears Harold J.
Published: January 2024

Eight Holstein cows, 4 inoculated intracistemally in 1 quarter of the mammary gland with Escherichia coli and 4 noninfected controls, were administered ceftiofur sodium (3 mg/kg of body weight, IV, q 12 hours) for 24 hours, beginning at 14 hours after inoculation of infected cows. All challenge-exposed cows became infected, with mean ± SEM peak log10 bacterial concentration in milk of 5.03 ± 0.69 colonyforming units/ml. The infection resulted in systemic signs (mean peak rectal temperature, 41.5 ± 0.3 C; anorexia; signs of depression) and local inflammation (mean peak albumin concentration in milk, 7.89 ± 1.71 mg/ml). Ceftiofur was detectable in milk from all challenge-exposed cows, compared with only 1 of 4 noninfected cows, and the mean period after inoculation that ceftiofur was detectable in milk was longer (P < 0.05) in infected (147.7 ± 27.5 hours) than noninfected cows (1.3 ± 1.3 hours). However, maximal ceftiofur concentration attained in milk for all cows was 0.28 p.g/ml, and was 0.20 jig/ml or less for all but 2 milk samples collected for 10 days after challenge exposure. Mean serum concentration of ceftiofur peaked at 1.0 ± 0.3 μg/ml and 0.7 ± 0.1 μg/ml for infected and noninfected cows, respectively. After each ceftiofur dose, mean peak and trough concentrations of ceftiofur in serum did not differ between groups; however, concentration of ceftiofur in serum was higher at 7 hours after each dose in noninfected cows, suggesting more rapid clearance of the drug in infected cows. Ceftiofur was not detected in serum (< 0.05 μg/ml) of any cow at or after 120 hours following inoculation of infected cows.

Storage of serum samples at —20 C for 3 weeks resulted in a 98.8% decrease in ceftiofur activity, compared with that in fresh serum samples. Eightyseven percent of this loss occurred 30 minutes after mixing serum and ceftiofur; thus, about 13% of the original activity was lost in storage. Storage of milk samples under similar conditions did not result in loss of ceftiofur activity.

Despite acute inflammation, the dosage of ceftiofur used in this trial would not result in drug concentrations in milk above FDA safe concentrations, or above the reported minimum inhibitory concentration for coliform bacteria.
Ototoxicity assessment of a gentamicin sulfate otic preparation in dogs
Authors: Strain George M. , Merchant Sandra R. , Neer T. Mark , Tedford Bruce L.
Published: January 2024

Vestibulotoxic and ototoxic effects often are seen after long-term, high-dose systemic treatment with gentamicin, but toxic effects after topical use have not been reported in animals, to the authors’ knowledge. Vestibular and auditory effects of twice daily otic gentamicin treatment for 21 days were evaluated in 10 dogs with intact tympanic membranes and in the same 10 dogs after experimental bilateral myringotomy. Each dog served as its own control; 7 drops of gentamicin sulfate (3 mg/ml in a buffered aqueous vehicle) were placed in 1 ear, and 7 drops of vehicle were placed in the opposite ear. Treatment and control ears were reversed after myringotomy. Vestibular function was evaluated daily by neurologic examination and behavioral assessment. Auditory function was evaluated twice weekly by determination of brain stem auditory evoked potentials. Gentamicin sulfate placed in the ear of clinically normal dogs with intact or ruptured tympanic membranes, in the quantities used in this study, did not induce detectable alteration of cochlear or vestibular function. Serum gentamicin concentration after 21 days of treatment was detectable in only 2 dogs and was an order of magnitude below documented toxic concentrations.
Encephalopathy in cattle experimentally infected with the scrapie agent
Authors: Clark Wilber W. , Hourrigan James L. , Hadlow William J.
Published: January 2024

Ten 8- to 10-month-old cattle were each inoculated intramuscularly, subcutaneously, intracerebrally, and orally with the scrapie agent to determine whether cattle are susceptible to it. Two inocula, both 10% homogenates of cerebrum, were used. One inoculum was from a sheep used for the second experimental ovine passage of the agent from 4 naturally affected Suffolk sheep. The other inoculum was from a goat used for the first experimental caprine passage of the agent from 2 naturally affected dairy goats living with the Suffolk sheep, the source of their infection. Between 27 and 48 months after inoculation, neurologic disease was observed in 1 of 5 cattle given the sheep brain homogenate and in 2 of 5 given the goat brain homogenate. In all 3 affected cattle, the disease was expressed clinically as increasing difficulty in rising from recumbency, stilted gait of the pelvic limbs, disorientation, and terminal recumbency during a 6- to 10-week course. Neurohistologic changes, though consistent with those of scrapie, were slight and subtle: moderate astrocytosis with sparse rod cells, some neuronal degeneration, a few vacuolated neurons, and scant spongiform change. Clinically and neurohistologically, the experimentally induced disease differed from bovine spongiform encephalopathy. The differences emphasize that such infections in cattle induce diverse responses, presumably depending largely on the strain of the agent. Pathologists should keep this variability in mind when looking for microscopic evidence of a scrapie-like encephalopathy in cattle.
Pharmacokinetics, nephrotoxicosis, and in vitro antibacterial activity associated with single versus multiple (three times) daily gentamicin treatments in horses
Authors: Godber Leanne M. , Walker Robert D. , Stein Gary E. , Hauptman Joe G. , Derksen Frederik J.
Published: January 2024

Once-daily administration of aminoglycosides may be a safe and effective therapeutic regimen, on the basis of the microbiologic and pharmacokinetic characteristics of these antibiotics. This study was designed to determine serum and tissue concentrations following IV administration of gentamicin, at dosages of 6.6 mg/kg of body weight, every 24 hours, and 2.2 mg/kg, every 8 hours, for 10 days in adult horses. Nephrotoxicosis from these dosage regimens also was compared, and microbiologic effects, including postantibiotic effects, were determined with various concentrations of gentamicin against an equine clinical isolate of Pseudomonas aeruginosa. Treatment at the 6.6-mg/kg dosage resulted in maximal serum concentrations (77.93 ± 19.90 μg/ml, mean ± sem) and area under the concentration-vs-time curves (83.79 ± 14.97 μg.h/ml) that were significantly (P < 0.05) greater than those following treatment at the 2.2-mg/kg dosage (5.05 ± 0.50 μg/ml and 6.03 ± 0.66 μg.h/ml, respectively). Nephrotoxicosis was not induced with either dosage regimen, and postantibiotic effects were prolonged with a higher gentamicin concentration. This study provided evidence to support the use of once-daily gentamicin treatment in adult horses.
Pharmacokinetics of caffeine in lactating dairy cows
Authors: DeGraves F. J. , Ruffin D. C. , Duran S. H. , Spano J. S. , Whatley E. M. , Schumacher J. , Riddell M. G.
Published: January 2024

Because caffeine is metabolized by the hepatic P-450 cytochrome oxidase system, clearance of caffeine is an excellent quantitative test of hepatic function in human beings. It is currently used in much the same way that creatinine clearance is used to assess renal function. Caffeine clearance was measured in lactating dairy cows initially to determine the suitability of caffeine clearance as an indicator of hepatic function in cattle. Pharmacokinetic variables of caffeine were studied in 6 adult lactating dairy cows after IV administration of a single dose of caffeine sodium benzoate (2 mg of caffeine/kg of body weight). Caffeine concentration was analyzed by use of an automated enzyme immunoassay. The lower limit of detection of the assay for caffeine in serum was 0.079 μg/ml. Serum caffeine concentration-time curves best fit an open two-compartment pharmacokinetic model. Harmonic mean elimination half-life was 3.8 (range, 2.6 to 6.9) hours, and total clearance was 0.118 (range, 0.090 to 0.197) L/kg/h. Milk caffeine concentration was similar to serum concentration 1.5 to 24 hours after caffeine administration. Adverse effects were not observed in cows given caffeine.
Anatomic and radiographic appearance of a sesamoid bone in the tendon of origin of the supinator muscle of the cat
Authors: Wood A. K. W. , McCarthy P. H. , Martin I. C. A.
Published: January 2024

Results of radiologic and anatomic studies of each cubital articulation (elbow) of a group of 50 adult cat cadavers indicated that a sesamoid bone may be located in a constantly present sesamoid cartilage associated with the tendon of origin of the supinator muscle. Radiography revealed a sesamoid bone in 40 of the 100 tendons of origin of the supinator muscles dissected from the elbows. The sesamoid bone articulated with the craniolateral aspect of the head of the radius, and the larger sesamoid cartilage, which contained the bone, articulated with the head of the radius and the capitulum of the humerus. Of several possible functions of the sesamoid cartilage (bone), it was considered that protection of the craniolateral part of the humeroradial articulation and maintenance of the complex anatomic system during joint movement were important. In radiographic views of the elbows of lame cats, the sesamoid bone should not be mistaken for a chip fracture or an osteocartilaginous loose body.
Determination of pharmacokinetics and pharmacodynamics of flunixin in calves by use of pharmacokinetic/phannacodynamic modeling
Authors: Landoni Maria F. , Cunningham Fiona M. , Lees P.
Published: January 2024

Pharmacokinetic and pharmacodynamic variables of flunixin were studied in calves after IV administration of the drug at a dose rate of 2.2 mg/kg of body weight. The anti-inflammatory properties of flunixin were investigated, using a model of acute inflammation; this involved surgically implanting tissue cages at subcutaneous sites and stimulating the tissue cage granulation tissue by intracavitary injection of carrageenan. The actions of flunixin on exudate concentrations of several substances related to the inflammatory process, including proteases (metalloprotease [active and total] and cysteine and serine proteases), enzymes (lactate dehydrogenase, acid phosphatase, and β-glucuronidase [β-glu]), eicosanoid (prostaglandin E2 [pge2], leukotriene B4, and serum thromboxane B2 [txb2]) concentrations, and bradykinin (BK)-induced edema, were investigated.

Flunixin had a long elimination half-life—6.87 ± 0.49 hours—and volume of distribution was 2.11 ± 0.37 L/kg, indicating extensive distribution of the drug in the body. Body clearance was 0.20 ± 0.03 L/ kg/h.

Flunixin exerted inhibitory effects on serum txb2 and exudate pge2 concentrations, β-glu activity, and BK-induced swelling. Other enzymes and inflammatory mediators were not significantly affected. Pharmacokinetic/pharmacodynamic modeling of the data revealed similar mean concentration producing 50% of the maximal effect values for inhibition of exudate pge2 and p-glu and of BK-induced swelling (0.070 ± 0.006, 0.064 ± 0.040, and 0.061 ± 0.030 μg/ml, respectively). A lower concentration producing 50% of the maximal effect value was obtained for inhibition of serum txb2 concentration (0.023 ± 0.004 μg/ml). Differences also were observed in equilibration halflife for these actions, suggesting the existence of 3 distribution compartments correlating with 3 sites of action—a central compartment and shallow and deep peripheral compartments. Pharmacokinetic/pharma- codynamic modeling proved to be a useful analytical method, providing a quantitative description of in vivo drug pharmacodynamics and indicating possible mechanisms of action.
Characterization of iron status in young dogs with portosystemic shunt
Authors: Bunch Susan E. , Jordan Holly L. , Sellon Rance K. , Cullen John M. , Smith Joseph E.
Published: January 2024

Microcytosis is a common laboratory finding in dogs with congenital portosystemic shunt (pss), although its pathogenesis is not yet understood. Because the most common cause of microcytosis in dogs is absolute or relative iron deficiency, iron status was evaluated in 12 young dogs with pss. Complete blood counting was done before surgical correction in all dogs, and in 5 dogs after surgery, by use of an automated hematology analyzer. Serum iron concentration and total iron-binding capacity (tibc) were determined coulometrically, and percentage of transferrin saturation was calculated. Erythrocyte protoporphyrin content was quantified by use of front-face fluorometry. Serum ferritin concentration was measured by use of elisa. Serum ceruloplasmin content was determined colorimetrically (with p-phenylene-diamine dihydrochloride as substrate) as an indirect indicator of subclinical inflammation, which may result in impaired iron utilization. Special stains were applied to liver (10 dogs; Gomori's) and bone marrow aspiration biopsy (7 dogs; Prussian blue) specimens for qualitative assessment of tissue iron content. Nonpaired Student's t-tests were used to compare serum iron concentration, tibc, percentage of transferrin saturation, and erythrocyte protoporphyrin, ferritin, and ceruloplasmin concentrations in dogs with pss with those in clinically normal dogs. All dogs had microcytosis before surgery; microcytosis resolved in 3 dogs after surgical correction. Serum iron concentration and tibc were significantly lower in pss-affected dogs than in clinically normal dogs. Erythrocyte protoporphyrin, ferritin, and ceruloplasmin concentrations in pss-affected dogs were not significantly different from those in healthy dogs. Excess iron was not detected consistently in liver or bone marrow samples. These results suggest that relative iron deficiency, perhaps associated with altered iron transport and not absolute iron deficiency, is related to microcytosis in dogs with pss.
Vaccination of cattle with outer membrane protein-enriched fractions of Pasteurella haemolytica and resistance against experimental challenge exposure
Authors: Morton Rebecca J. , Panciera Roger J. , Fulton Robert W. , Frank Glynn H. , Ewing Sidney A. , Homer John T. , Confer Anthony W.
Published: January 2024

Administration of an N-lauroylsarcosine-derived outer membrane protein fraction of Pasteurella haemolytica A1 (sci-1) induced a protective response in calves against intrathoracic challenge exposure with the homologous serovar. Outer membrane proteins from heterologous serovars, A6 and A9, induced partial protection that was associated with their respective similarities to serovar A1 in outer membrane protein profiles derived by use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Calves vaccinated with sci preparations did not have detectable neutralizing antibody to P haemolytica A1 leukotoxin. Antibodies to whole-cell antigens, carbohydrate-protein subunit antigen, and sci-1 were associated with resistance, which indicates that protein antigens shared among cell surface, carbohydrate-protein subunit, and sci preparations are immunogenic and enhance resistance to experimental challenge exposure.
In vitro of modulation of bovine blood neutrophils and mononuclear cells by oxytetracycline
Authors: Myers Michael J. , Farrell Dorothy E. , Henderson Mark
Published: January 2024

The effect of oxytetracycline (otc) on bovine blood mononuclear cells and neutrophil functions was examined in vitro. Neutrophil functions tested include respiratory burst, peroxidase, and antibacterial activities. Neutrophils were treated with otc (10 to 1,500 μg/ml) before exposure to either opsonized zymosan or bacteria. A dose-response inhibition antibacterial activity to high concentrations of otc (500 to 1,000 μg/ml) was observed. Beginning at a concentration 15 μg/ml, otc treatment of neutrophil lysates resulted in decreased peroxidase activity. A dose response was not observed. In contrast, respiratory burst, measured by nitroblue tetrazolium dye reduction, increased after otc exposure, but only at high concentrations (500 and 1,000 μg/ml) of otc. Mitogen-induced proliferation of blood mononuclear cells cocultured with otc and concanavalin A, phytohemagglutinin-P, or pokeweed mitogen was inhibited at an otc concentration of 100 μg/ml at 48 and 72 hours of culture. These results indicate that blood mononuclear cells are more sensitive to the inhibitory effects of otc than are neutrophils. Furthermore, the otc-mediated inhibition of neutrophil antimicrobial activity is inversely related to the increase in nitroblue tetrazolium reduction. This suggests that otc is uncoupling the hexose monophosphate shunt from production of secreted oxygen radicals. These results also suggest that the peroxidase enzyme system has a large biological reserve capacity.