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Abstract

Objective—To determine the effects of interleukin (IL)-1β on matrix synthesis and degradation by chondrocytes cultured in a 3-dimensional (3-D) gel medium.

Sample Population—Chondrocytes from 7 dogs.

Procedure—Articular chondrocytes were harvested and cultured in 3-D gel medium alone or with 10 or 20 ng IL-1βml that was added beginning on day 0, 3, 6, or 9. On days 3, 6, 12, and 20 of 3-D culture, samples of the liquid medium were evaluated for glycosaminoglycan (GAG), prostaglandin E2 (PGE2), and matrix metalloprotease (MMP)-3 content. The 3-D plug in each well was evaluated for histologic characteristics of viability, cell morphology, and proteoglycan staining, immunohistochemically stained for collagen type II, and spectrophotometrically analyzed for GAG content.

Results—Significant differences for all variables were detected between controls and each IL-1β group, among groups with different IL-1β concentrations, and among groups with IL-1β added at various time points. Chondrocytes exposed to IL-1β had loss of GAG, increased PGE2 and MMP-3 concentrations, and lack of collagen type-II synthesis. These IL-1β effects appeared to be time and concentration dependent.

Conclusions—Addition of IL-1β to chondrocytes in 3- D gel medium results in time- and concentrationdependent effects on matrix synthesis and degradation and provides an appropriate in vitro model for many of the pathophysiologic events associated with osteoarthritis. (Am J Vet Res 2000;61:766–770)

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in American Journal of Veterinary Research

Abstract

Objectives—To determine the sensitivity of bacteriologic culture of pooled fecal samples in detecting Mycobacterium paratuberculosis, compared with bacteriologic culture of individual fecal samples in dairy cattle herds.

Study Design—Cross-sectional study.

Animals—24 dairy cattle herds.

Procedure—Individual and pooled fecal samples were submitted for bacteriologic culture, and results were compared between these groups.

Results—Ninety-four and 88% of pooled fecal samples that contained feces from at least 1 animal with high (mean, ≥ 50 colonies/tube) and moderate (mean, 10 to 49 colonies/tube) concentrations of M paratuberculosis, respectively, were identified by use of bacteriologic culture of pooled fecal samples. Prevalences of paratuberculosis determined by bacteriologic culture of pooled and individual fecal samples were highly correlated.

Conclusions and Clinical Relevance—Bacteriologic culture of pooled fecal samples provided a valid and cost-effective method for the detection of M paratuberculosis infection in dairy cattle herds and can be used to estimate prevalence of infection within a herd. (J Am Vet Med Assoc 2003;223:1022–1025)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the effects of varios concentrations of L-lysine and L-arginine on in vitro replication of feline herpesvirus type-1 (FHV-1).

Sample Population—Cultured Crandell-Reese feline kidney (CRFK) cells and FHV-1 strain 727.

Procedure—Uninfected CRFK cells or CRFK cells infected with FHV-1 were cultured in Dulbecco's modified Eagle's medium or in 1 of 7 test media containing various concentrations of lysine and arginine. Viral titer and CRFK growth rate were assessed in each medium.

Results—Media depleted of arginine almost completely inhibited viral replication, whereas 2.5 or 5.0 µg of arginine/ml of media was associated with a significant increase in FHV-1 replication. In media with 2.5 µg of arginine/ml, supplementation with 200 or 300 µg of lysine/ml reduced viral replication by 34.2 and 53.9%, respectively. This effect was not seen in media containing 5.0 µg of arginine/ml. Growth rates of CRFK cells also were suppressed in media containing these concentrations of amino acids, but they were not significantly different from each other.

Conclusions and Clinical Relevance—Arginine exerts a substantial growth-promoting effect on FHV-1. Supplementation of viral culture medium with lysine attenuates this growth-promoting effect in media containing low concentrations of arginine. Analysis of data from this study indicates that high concentrations of lysine reduce in vitro replication of FHV-1 but only in media containing low concentrations of arginine. Clinical trials will be necessary to determine whether supplemental administration of lysine, with or without arginine restriction, will be useful in the management of cats with FHV-1 infections. (Am J Vet Res 2000; 61:1474–1478)

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in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of experimental infection with bovine viral diarrhea virus (BVDV) on llamas and their fetuses, evaluate seroprevalence of BVDV in llamas and alpacas, and genetically characterize BVDV isolates from llamas.

Design—Prospective study.

Animals—4 pregnant llamas for the experimental infection study and 223 llamas and alpacas for the seroprevalence study.

Procedure—Llamas (seronegative to BVDV) were experimentally infected with a llama isolate of BVDV via nasal aerosolization. After inoculation, blood samples were collected every other day for 2 weeks; blood samples were obtained from crias at birth and monthly thereafter. For the seroprevalence study, blood was collected from a convenience sample of 223 camelids. Isolates of BVDV were characterized by reverse transcription- polymerase chain reaction assay.

Results—Viremia and BVDV-specific antibody response were detected in the experimentally infected llamas, but no signs of disease were observed. No virus was detected in the crias or aborted fetus, although antibodies were evident in crias after colostrum consumption. Seroprevalence to BVDV was 0.9% in llamas and alpacas. Sequences of the llama BVDV isolates were comparable to known bovine isolates.

Conclusions and Clinical Relevance—Findings suggest that llamas may be infected with BVDV but have few or no clinical signs. Inoculation of llamas during gestation did not result in fetal infection or persistent BVDV infection of crias. Seroprevalence to BVDV in llamas and alpacas is apparently low. The most likely source for BVDV infection in camelids may be cattle. (J Am Vet Med Assoc 2003;223:223–228)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine efficacy and safety of a commercial modified-live canine distemper virus (CDV) vaccine used for prophylaxis in domestic ferrets.

Animals—Sixteen 16-week-old neutered male ferrets.

Procedures— Equal groups of ferrets were inoculated subcutaneously at 16 and 20 weeks of age with saline (0.9% NaCl) solution or a vaccine derived from the Onderstepoort CDV strain and attenuated in a primate cell line. Live virulent CDV was administered to all ferrets intranasally and orally 3 weeks after the second inoculation. Clinical signs and body weights were monitored regularly during the study. Blood samples for serologic examination were drawn prior to each inoculation, before challenge exposure, and 10, 15, and 21 days after exposure. Blood samples for reverse transcriptase polymerase chain reaction (RT-PCR) were obtained 5 days after the first vaccination, and 5, 10, 15, and 21 days after challenge exposure.

Results—After challenge exposure, control ferrets had significantly more clinical signs and weight loss, compared with vaccinates. All vaccinated ferrets survived, whereas all control ferrets died. The RT-PCR assay was successful in detecting CDV in blood and fresh or formalin-fixed tissues from infected ferrets.

Conclusions and Clinical Relevance—Findings suggest that the vaccine when given SC to domestic ferrets as directed is safe and protective against challenge exposure with virulent CDV. The RT-PCR assay may simplify detection of CDV in fresh and fixed tissues. (Am J Vet Res 2001;62:736–740)

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in American Journal of Veterinary Research

Abstract

Objective—To monitor ovine herpesvirus type 2 (OvHV-2) infection status and the association between OvHV-2 infection and development of clinical signs of malignant catarrhal fever (MCF) in cattle.

Design—Longitudinal study.

Animals—30 mature adult cows and 18 cattle submitted for necropsy.

Procedure—Blood and milk samples were collected at monthly intervals from 30 adult cows for 20 consecutive months. Nasal and ocular swab specimens were also collected during months 9 through 20. Polymerase chain reaction (PCR) assay for detection of OvHV-2 was performed on blood, milk, nasal swab, and ocular swab specimens. Competitive inhibition ELISA (CI-ELISA) for detection of antibodies against MCF viruses was performed on serum samples obtained prior to study initiation and monthly during the last 12 months. Tissues obtained from herdmates without clinical signs of MCF that were submitted for necropsy were analyzed for OvHV-2 DNA via PCR assay for possible sites of latency.

Results—Initially, 8 of 30 cows had positive CI-ELISA results. Seroconversion was detected in 4 cows. Ovine herpesvirus type 2 DNA was intermittently detected in blood, milk, nasal secretions, or ocular secretions from 17 of 30 cows. Twenty-one cows had positive CI-ELISA or PCR assay results. No cattle in the study developed clinical signs of MCF. Results of PCR assays performed on tissue samples from 2 of 18 animals submitted for necropsy were positive for OvHV-2.

Conclusions and Clinical Relevance—OvHV-2 infection can occur in cattle without concurrent development of clinical MCF. Ovine herpesvirus type 2 DNA was detected intermittently, suggesting fluctuating viral DNA loads or reinfection in subclinical cattle. A definitive site of latency was not identified from tissues obtained during necropsy. (J Am Vet Med Assoc 2005;227:606–611)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether flies can acquire porcine reproductive and respiratory syndrome virus (PRRSV) and disperse the virus throughout a designated area.

Animals—60 four-month-old pigs.

Procedure—On day 0, 28 of 60 pigs were inoculated with PRRSV MN 30-100 (index variant). On the same day, 100,000 pupae of ochre-eyed houseflies and 100,000 pupae of red-eyed (wild-type) houseflies were placed in the swine facility for a release-recapture study. Flies were recaptured at 2 locations within the swine facility, 6 locations immediately outside the facility, and 30 locations 0.4, 0.8, 1.3, 1.7, 1.9, and 2.3 km from the facility. Traps were emptied on days 2, 7, 8, 10, and 14. Samples derived from flies were tested by use of a polymerase chain reaction assay, virus DNA was sequenced, and viruses were tested for infectivity by means of a swine bioassay.

Results—PRRSV RNA homologous to the index PRRSV was detected in trapped flies collected inside and immediately outside the facility and from 9 of 48 samples collected at 0.4 km, 8 of 24 samples collected at 0.8 km, 5 of 24 samples collected at 1.3 km, and 3 of 84 samples collected at > 1.7 km from the facility. Two samples collected at 0.8 km contained genetically diverse variants of PRRSV. Swine bioassays revealed the virus in flies was infectious.

Conclusions and Clinical Relevance—Flies appeared to become contaminated with PRRSV from infected pigs and transported the virus ≥ 1.7 km. Flyborn transmission may explain how PRRSV is seasonally transported between farms. (Am J Vet Res 2004;65:1284–1292)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the influences of animal age, bacterial coinfection, and porcine reproductive and respiratory syndrome virus (PRRSV) isolate pathogenicity on virus concentration in pigs.

Animals—Twenty-one 2-month-old pigs and eighteen 6-month-old pigs.

Procedure—Pigs were grouped according to age and infected with mildly virulent or virulent isolates of PRRSV. The role of concurrent bacterial infection was assessed by infecting selected pigs with Mycoplasma hyopneumoniae 21 days prior to inoculation with PRRSV. On alternating days, blood and swab specimens of nasal secretions and oropharyngeal secretions were collected. On day 21 after inoculation with PRRSV, selected tissues were harvested. Concentrations of PRRSV were determined by use of quantitative real-time PCR and expressed in units of TCID50 per milliliter (sera and swab specimens) or TCID50 per gram (tissue specimens).

Results—Concentrations of virus were higher in blood and tonsils of pigs infected with virulent PRRSV. Pigs infected with virulent PRRSV and M hyopneumoniae had significantly higher concentrations of viral RNA in lymphoid and tonsillar tissue. Coinfection with M hyopneumoniae resulted in a higher viral load in oropharyngeal swab specimens and blood samples, independent of virulence of the PRRSV isolate. Two-month-old pigs had significantly higher viral loads in lymph nodes, lungs, and tracheal swab specimens than did 6-month-old pigs, independent of virulence of the PRRSV isolate.

Conclusions and Clinical Relevance—Multiple factors affect PRRSV concentration in pigs, including pathogenicity of the PRRSV isolate, age, and concurrent infection with M hyopneumoniae.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate sensitivities at the herd level of test strategies used in the Voluntary Johne's Disease Herd Status Program (VJDHSP) and alternative test strategies for detecting dairy cattle herds infected with Mycobacterium paratuberculosis.

Design—Nonrandom cross-sectional study.

Sample Population—64 dairy herds from Pennsylvania, Minnesota, Colorado, Ohio, and Wisconsin. Fifty-six herds had at least 1 cow shedding M paratuberculosis in feces; the other 8 herds were free from paratuberculosis.

Procedure—For all adult cows in each herd, serum samples were tested for antibodies to M paratuberculosis with an ELISA, and fecal samples were submitted for bacterial culture for M paratuberculosis. Sensitivities at the herd level (probability of detecting infected herd) of various testing strategies were then evaluated.

Results—Sensitivity at the herd level of the testing strategy used in level 1 of the VJDHSP (use of the ELISA to test samples from 30 cows followed by confirmatory bacterial culture of feces from cows with positive ELISA result) ranged from 33 to 84% for infected herds, depending on percentage of cows in the herd with positive bacterial culture results. If follow- up bacterial culture was not used to confirm positive ELISA results, sensitivity ranged from 70 to 93%, but probability of identifying uninfected herds as infected was 89%.

Conclusions and Clinical Relevance—Results suggest that the testing strategy used in the VJDHSP will fail to identify as infected most dairy herds with a low prevalence of paratuberculosis. A higher percentage of infected herds was detected if follow-up bacterial culture was not used, but this test strategy was associated with a high probability of misclassifying uninfected herds. (J Am Vet Med Assoc 2002;220: 1053–1057)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine risk factors for lens luxation and cataracts in captive pinnipeds in the United States and the Bahamas.

Design—Cross-sectional study.

Animals—111 pinnipeds (99 California sea lions [Zalophus californianus], 10 harbor seals [Phoca vitulina], and 2 walruses [Odobenus rosmarus]) from 9 facilities.

Procedures—Eyes of each pinniped were examined by a veterinary ophthalmologist for the presence of cataracts or lens luxations and photographed. Information detailing husbandry practices, history, and facilities was collected with a questionnaire, and descriptive statistical analyses were performed for continuous and categorical variables. Odds ratios and associated 95% confidence intervals were estimated from the final model.

Results—Risk factors for lens luxation, cataracts, or both included age ≥ 15 years, history of fighting, history of ocular disease, and insufficient access to shade.

Conclusions and Clinical Relevance—Diseases of the lens commonly affect captive pinnipeds. Access to UV-protective shade, early identification and medical management of ocular diseases, and prevention of fighting can limit the frequency or severity of lens-related disease in this population. An extended life span may result from captivity, but this also allows development of pathological changes associated with aging, including cataracts.

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in Journal of the American Veterinary Medical Association