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SUMMARY

Laboratory raised white-footed mice (Peromyscus leucopus) were inoculated experimentally with live spirochetes (Borrelia burgdorferi), the etiologic agent of Lyme disease (borreliosis). Prior to inoculation, mouse sera were tested with an indirect fluorescent antibody test, and all mice were seronegative. All inoculated mice seroconverted. In tick transmission studies, immature stages of Ixodes dammini and Dermacentor variabilis attached and fed to repletion on mice, but only I dammini transferred spirochetes to uninfected mice. Mice were susceptible to oral infection and transmitted infection to each other through direct contact. Infection did not affect reproduction or development of young born from infected dams, nor did spirochetes appear in the tissues of neonates. Borrelia burgdorferi spirochetes were identified in the kidneys, liver, and spleen of infected mice by the use of the modified Steiner silver stain and a tissue indirect fluorescent antibody test. Spirochetes also were isolated in culture of the heart blood of 1 mouse. Regardless of the source of infection, no mice developed clinical signs or had any pathologic change resulting from infection. Spirochetes were always observed extracellularly within interstitial spaces. Antibody titers persisted for over 4 months in some mice and spirochetes were found in the tissues of 1 mouse that had been infected 1 year earlier.

Free access
in American Journal of Veterinary Research

SUMMARY

Effects of immunosuppression were compared in newly hatched chickens given cyclophosphamide (cy) after inoculation with avian nephritis virus (anv). All cy-treated infected chickens died within 13 days after inoculation of the virus and had heavy urate deposits throughout the body. However, non-cy-treated infected, cy-treated noninfected, and non-cy-treated noninfected control chickens survived through the observation period. In a chronologic study, the value of serum uric acid in cy-treated infected chickens was more than 3 times higher than that in non-cy-treated infected chickens, and more than 9 times higher than in noninfected chickens. Serum uric acid values were coincident with the positive degree of anv antigen in the tubular epithelial cells in the kidneys and with the severity of renal degeneration. Serologic and immunohistologic examinations did not reveal detectable antibody and IgG- and IgM-containing cells in the spleen and kidneys of cy-treated infected chickens. However, non-cy-treated infected chickens had an increased number of IgM- and IgG-containing cells and antibody against anv on postinoculation day 6. These findings demonstrated that cy treatment enhanced the susceptibility of chickens to anv infection.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To elucidate the spatial and temporal expression of a porcine lactoferrin (LTF) gene.

Animals

4 female and 4 male Large White pigs.

Procedures

We examined LTF expression in various organs excised from the pigs, using northern blot hybridization with a porcine LTF cDNA probe. Antibodies against porcine LTF were raised in rabbits and were used along with immunohistochemical staining to localize the LTF protein.

Results

High amounts of porcine LTF mRNA were detected in the secreting mammary gland and epididymis. This distribution is consistent with that of porcine LTF examined by immunohistochemistry. In female pigs, porcine LTF mRNA concentration increased remarkably in the ductal cells of the lactating mammary gland then significantly decreased at day 21 after parturition. Furthermore, specific staining for LTF was observed in the epithelial cells of the gastrointestinal tract of female pigs, but not in the uterus, ovaries, spleen, kidneys, pancreas, muscles, heart, brain, lungs, or liver of postpartum female pigs, or in the testes of male pigs.

Conclusions

Gene expression of porcine LTF is closely related to lactation in the mammary gland. Distribution of LTF in the epididymis suggests that LTF may have a regulatory role in development of the reproductive tract of male pigs. (Am J Vet Res 1997;58:1152–1158)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To identify eosinophil progenitor cells in feline bone marrow, establishing an assay method to use in studies of eosinophilopoiesis and eosinophilopoietic factors in cats.

Animals

Healthy, laboratory animal source cats.

Procedure

Sources of colony-stimulating activity were prepared by conditioning media with bone marrow, spleen, and blood mononuclear cells from cats infected with Toxocara canis. Bone marrow cells were aspirated and cultured to develop the eosinophil progenitor cell assay and to test cells from 9 healthy cats in the assay.

Results

Optimal conditions for identifying colonyforming units-eosinophil and cluster-forming units-eosinophil were as follows. Bone marrow mononuclear cells (105) were plated in 1 ml of supplemented medium, fetal bovine serum, and agar. The source of eosinophil growth factor(s) was bone marrow-conditioned medium made in the presence of 2.5 µg of concanavalin A/ml; other conditioned media also supported eosinophil colony growth. Dishes were incubated for 7 days at 37 C and 7% CO2. The colonyforming units-eosinophil formed aggregates of > 50 Luxol fast blue-positive cells and had dispersed morphology; the cluster-forming units-eosinophil formed aggregates of < 50 cells.

Conclusion and Clinical Relevance

Similar to other species, cats have separate and distinct eosinophil progenitor cells. The eosinophil progenitor assay may be used to characterize altered kinetics of eosinophilopoiesis, to assess eosinophil growth factors, and to evaluate therapeutic regimens that might be useful in the management of excess eosinophil production. (Am J Vet Res 1997; 58:348-353)

Free access
in American Journal of Veterinary Research

Abstract

Laparoscopy was performed on 6 horses (2 mares, 2 geldings, 2 stallions) to determine the normal laparoscopic anatomy of the equine abdomen. After withholding feed for 36 hours, horses were examined from the left and right paralumbar fossae, and the visceral anatomic structures were recorded by videotape and photography. One mare developed emphysema located subcutaneously at the primary laparoscopic portal; otherwise, there were no complications. The anatomic structures of diagnostic importance that were observed in the left half of the abdomen were the hepatic duct; left lateral and quadrate lobes of the liver; stomach; spleen; left kidney with the associated nephrosplenic ligament; segments of jejunum, descending colon, and ascending colon; left side of the male and female reproductive tracts; urinary bladder; vaginal ring; and mesorchium. Important structures observed in the right side of the abdomen were portions of the common hepatic duct; left lateral, quadrate, and right lobes of the liver; caudate process of the liver; stomach; duodenum; right dorsal colon, epiploic foramen; omental bursa; right kidney; base of the cecum; segments of jejunum, descending colon, and ascending colon; urinary bladder; right half of the male and female reproductive tracts; and rectum.

Free access
in American Journal of Veterinary Research

Objective

To describe 3 laparoscopic approaches for, and the normal laparoscopic anatomy of, the abdomen in adult llamas and to evaluate the effects of laparoscopy in those llamas.

Design

Prospective clinical trial.

Animals

Six adult castrated male llamas.

Procedure

After induction of general anesthesia, 3 surgical approaches to the abdomen were performed: left paralumbar, ventral midline, and right paralumbar. The abdomen was systematically examined, and anatomic features described. After recovery from anesthesia, all llamas were examined daily for 10 days and CBC was repeated 24, 72, and 120 hours after laparoscopy.

Results

Laparoscopy was successfully performed in all llamas by use of the ventral midline and right paralumbar approaches. The laparoscope was inadvertently placed into the left retroperitoneal space in 1 of the 6 llamas when the left paralumbar approach was used. Also, hemorrhage into the abdomen limited the view from the left side in another llama. Various approaches allowed viewing of the first and third forestomach compartments, liver, spleen, kidneys, small intestine, ileum, proximal loop of the ascending colon, spiral colon, and urinary bladder. Postoperative findings included subcutaneous emphysema and edema. Mean WBC count peaked 24 hours after surgery (mean, 23,500 cells/μl). Generally, neutrophil count increased and lymphocyte count decreased during the 120 hours after surgery.

Clinical Implications

Laparoscopy may be used for differentiation of medical and surgical lesions in the abdomen of llamas. The site for laparoscopy should be chosen on the basis of the most likely site of the suspected lesion.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To assess whether foot-and-mouth disease virus (FMDV)-specific sequences could be identified in tissues from persistently virus-infected animals.

Design

Cattle with experimentally induced persistent FMDV infections were slaughtered at 750 days after viral exposure. Experimentally infected pigs were slaughtered at 28 days after FMDV inoculation. Postmortem specimens were asceptically removed.

Animals

Three bovids and 3 pigs were studied, as well as 1 control animal for each species.

Procedure

Various tissues were examined for the presence of FMDV-specific sequences by dot-blot hybridization assay, using a molecularly cloned FMDV cDNA corresponding to the polymerase coding region.

Results

The FMDV-specific genomic sequences were only detected in RNA from spleen, lung, larynx, tonsils, pancreas, liver, esophagus, and WBC of bovids.

Conclusions

It was established that, at late stages of the persistent infection, when virus isolation was not possible, cattle may carry FMDV-specific sequences in different tissues. Retention of viral sequences could not be demonstrated in specimens from experimentally infected swine, 28 days after viral inoculation.

Free access
in American Journal of Veterinary Research

Objective—

To evaluate the potential food safety risks constituted by recumbent cattle that are slaughtered for edible beef.

Design—

Prospective case series.

Animals—

Thirty cattle in recumbency that passed a routine antemortem inspection at a US federally inspected abattoir.

Procedure—

Aerobic, bacteriologic culture of blood samples taken immediately prior to slaughter and of spleens taken during viscera inspection. Gross lesions were recorded, and samples of liver, lung, kidney, and heart were collected from each animal for routine light microscopic examination.

Results—

Bacteremia caused by Salmonella dublin was documented in 1 cow that had arthritis. Two other cows were condemned after postmortem inspection: 1 because of pneumonia and pleuritis and the other because of vegetative endocarditis. Three carcasses were retained and later condemned because of antibiotic residues in tissues; 1 of these cows had mastitis, 1 had liver abscesses, and 1 was the cow with vegetative endocarditis. Sarcocystosis was found in 27 of 30 hearts, but other clinically important histologic lesions were observed only in liver samples. In 11 of the 30 cows, multifocal, microscopic foci of hepatitis were observed, suggesting that terminal embolic bacterial showering of the liver had occurred in these animals. Liver samples were not submitted for bacteriologic culture.

Clinical Implications—

Most recumbent cows slaughtered for edible beef are not contaminated by bacteria; however, the viscera from these animals may present a food safety danger. Efforts should be made to develop rapid tests to identify bacteremic animals at slaughter and to more fully evaluate terminal showering of viscera by bacteria in cattle at slaughter.

Free access
in Journal of the American Veterinary Medical Association

Summary

Concentration of sulfamethazine was measured in plasma and tissues (fat, liver, kidney, spleen, lungs, and skeletal muscle) of pigs given the drug iv and po. The plasma concentration vs time curve was best described by a 2-compartment model, with a distribution half-life of 0.46 hour and an elimination halflife of 16.9 hours. Bioavailability after oral administration was 85.8 ± 5.3%.

The tissue and plasma sulfamethazine concentration vs time data were used to develop a multicompartment pharmacokinetic model of sulfamethazine disposition in pigs. Plasma and tissue concentrations of sulfamethazine in pigs were measured at various intervals after multiple oral doses of sulfamethazine, and were compared to concentrations predicted by the model. Model predictions for tissue concentrations of sulfamethazine after addition of the drug to feed (110 μg/g of feed for 98 days; 550 μg/g for 30 days) were compared to results from other studies. The model accurately predicted the number of days for sulfamethazine concentration to fall below 0.1 μg of tissue/g (0.1 ppm, the tolerated concentration) in various tissues.

Free access
in American Journal of Veterinary Research

Summary

The B1 strain of Newcastle disease virus (ndv-B1), which is nonpathogenic for newly hatched chickens, killed embryos when it was used to inoculate chicken eggs at embryonation day 18. Treatment of ndv-B1 with an alkylating agent, ethylmethane sulfonate (ems) markedly reduced the pathogenicity of the virus for 18-day-old chicken embryos. Eggs inoculated with the modified virus (ndv-B1-ems) hatched, and the virus was isolated from lungs and spleen of 1-day-old chickens. The hatched chickens developed antibody to ndv and were protected against challenge exposure (at 4 weeks of age) with a highly virulent GB-Texas strain of ndv. Presence of maternal antibody to ndv in embryonating eggs did not influence the protective ability of ndv-B1-ems, which also induced protective immunity when administered to 4-week-old chickens. The 50% protective dose of ndv-B1-ems in maternal antibody-negative and -positive embryos was calculated to be 10.77 and 17.70 embryo 50% lethal doses, respectively. Results of the study indicated that ndv-B1-ems may be used as an embryo vaccine to protect chickens against Newcastle disease.

Free access
in American Journal of Veterinary Research