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Abstract

Objective

To evaluate effects of thermal environment on response to acute peripheral lipopolysaccharide (LPS) challenge exposure in neonatal pigs.

Animals

26 neonatal pigs.

Procedure

Pigs were assigned to the following treatment groups: 1 warm environment/LPS; 2 warm environment/saline solution; 3 cool environment/LPS; and 4 cool environment/saline solution. For each pig given LPS. 1 littermate of the same sex was given saline solution. Sows with baby pigs were housed in a warm (32 C) or cool (21 C) thermal environment. At 28 days of age, pigs were given 150 µg/kg of body weight of Escherichia coli LPS or saline solution intraperitoneally as a control. Rectal temperature and signs of sickness were monitored for 3 hours after LPS administration, when pigs were euthanatized and blood samples were collected to determine serum concentrations of tumor necrosis factor (TNF) α and cortisol. To determine in vitro production of TNFα, alveolar macrophages were collected by tracheal lavage and incubated for 24 hours at 37 or 41 C, with or without LPS (10 µg/ml).

Results

Thermal environment had a significant (P = 0.0004) effect on rectal temperature; LPS administration induced a febrile response (P = 0.0007) only in pigs in the warm environment. All LPS-injected pigs developed signs of endotoxemia; serum TNFα and cortisol concentrations were significantly increased (TNFα, P = 0.003; cortisol, P = 0.0001); there was no significant in vivo thermal effect on serum TNFα and cortisol concentrations. LPS-stimulated alveolar macrophages produced significantly less (P = 0.0086) TNFα when incubated at 41 C.

Conclusions

Thermal environment can have a significant impact on the response of neonatal pigs exposed to bacterial endotoxins. (Am J Vet Res 1997; 58:364-369)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To evaluate use of the virulence-associated protein of Rhodococcus equi in immunizing foals against R equi pneumonia.

Animals

Eight (experimental group) and 6 (controls) mares with their foals.

Procedure

Virulence-associated protein extracted from R equi was used to prepare an acetone-precipitated, Triton ×-extracted (APTX) antigen. After determination of the efficacy of passive immunization, in untreated foals or in foals given plasma from a horse vaccinated with APTX antigen or from a nonvaccinated horse, a field trial was done to evaluate the efficacy of vaccination of 8 mares, twice with APTX before parturition, and of their foals at ages 3 and 5 weeks; 6 mares and their foals served as unvaccinated controls. All 2-day-old foals were given plasma from local donor horses inoculated with a locally produced bacterin. Serum opsonizing activity produced by vaccination with APTX was determined. Passively immunized foals were challenge exposed with an aerosol of virulent R equi. Foals of the field trial were exposed to enzootic R equi infection.

Results

Inoculation with APTX resulted in high IgG antibody titers with opsonizing activity. Passive immunization of foals with plasma from an immunized horse enhanced bacterial clearance from the lungs, compared with that in foals not given plasma or given plasma without APTX antibodies. Vaccination of mares and foals exposed to natural infection resulted in development of R equi pneumonia in 4 of 8 vaccinated foals, but in only 1 of 6 unvaccinated foals,.

Conclusions

Vaccination with APTX antigen led to high-titer, opsonizing antibody. Plasma from a vaccinated horse appeared to enhance clearance of R equi from the lungs of foals. Paradoxically, vaccination of mares and their foals with APTX antigen did not protect foals and may have enhanced R equi pneumonia in the foals. (Am J Vet Res 1997;58:356-359)

Free access
in American Journal of Veterinary Research

Abstract

Objective

Baculovirus-expressed transmissible gastroenteritis virus (TGEV) spike (S) glycoprotein vaccines were inoculated parenterally in swine to determine whether such vaccines could induce serum and whey virus-neutralizing (VN) antibodies and protective lactogenic immunity for TGEV-challenge-exposed pigs.

Animals and Procedures

3 recombinant baculoviruses that expressed full or partial length TGEV Miller strain S glycoproteins were inoculated SC in 17 conventionally raised 11-day-old TGEV-seronegative pigs to determine whether the recombinant S glycoproteins would elicit serum VN antibodies. Eleven TGEV-seronegative pregnant sows were inoculated SC or intramammarily with subunit vaccines (R2-2 or R3-5) or control proteins. Pigs born to 9 of the 11 sows were challenge exposed at 4 to 5 days of age with the virulent Miller strain, and passive immunity was assessed. Serum and whey antibody responses to TGEV were analyzed by VN and ELISA testing.

Results

Recombinant S glycoproteins (R2-2 or R3-5) containing the 4 major antigenic sites induced similar VN antibody titers to TGEV in serum and colostrum, but low (some sows) or no VN antibody titer was detected in milk. Subcutaneous inoculation of sows with R2-2 or R3-5 elicited IgG, but not IgA antibodies to TGEV in colostrum. Morbidity was 100%, and mortality ranged from 20 to 80% in TGEV challenge-exposed pigs nursing sows inoculated SC or intramammarily with TGEV S glycoprotein vaccines.

Conclusions and Clinical Relevance

Parenterally administered TGEV S glycoprotein vaccines elicit VN antibodies to TGEV in serum and colostrum that do not fully provide active or passive immunity in swine. (Am J Vet Res 1997;58:242–250)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To characterize the relation between bronchoalveolar and blood eosinophil numbers, serum total IgE concentration, and nonspecific airway reactivity in healthy dogs.

Animals

26 healthy Beagles.

Procedure

Prior to measurement of nonspecific airway responsiveness, dogs were anesthetized and bronchoscopy was performed to recover bronchoalveolar lavage (BAL) fluid. Repeated measurements were made in 6 dogs.

Results

The percentage of blood eosinophils varied between 0 and 13 (mean ± SD, 5.6 ± 3.6) %, the percentage of eosinophils in BAL fluid ranged between 0 and 63.5 (8.8 ± 12.9) %, and total serum IgE concentration was 0.1 to 107.5 (23.4 ± 29.1) U/ml. A strong association was evident between numbers of blood eosinophils and total serum IgE concentration (R 2 = 0.413, P < 0.001), and a trend toward an association between numbers of blood eosinophils and numbers of eosinophils in BAL fluid was apparent (R 2 = 0.110, P = 0.053). Significant associations were not found between any other aspects of the blood and BAL fluid cell profiles and total serum IgE concentration or airway reactivity. Serum total IgE concentration was not associated with airway reactivity. Further, in dogs examined on repeated occasions, variation in BAL fluid eosinophil numbers was not associated with any change in serum total IgE concentration or airway reactivity.

Conclusions

Neither numbers of bronchoalveolar or blood eosinophils nor serum total IgE concentration have a significant role in determining airway reactivity in healthy dogs. (Am J Vet Res 1997;58:34–39)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine the role of tissue factor (TF) in the coagulation events leading to intra-alveolar fibrin deposition and intravascular thrombosis associated with pneumonic pasteurellosis in cattle.

Animals

Healthy 2- to 4-week-old male Holstein calves.

Procedures

Blood and bronchoalveolar lavage samples were collected before and at 1, 2, 4, and 6 hours after inoculation of saline solution or Pasteurella haemolytica. Total leukocyte count, platelet count, plasma total protein concentration, prothrombin time, and partial thromboplastin time were measured in blood samples. Total nucleated cell count, total protein concentration, and procoagulant activity were measured in bronchoalveolar lavage samples. Additionally, platelet survival in blood, platelet accumulation in affected lung tissue, and gross and microscopic lung lesions were determined.

Results

Administration of TF monoclonal antibodies (MAB) TF1-1F7 prevented the decrease in platelet survival and the increase in bronchoalveolar lavage fluid TF-dependent procoagulant activity observed in calves not treated with MAB TF1-1F7 antibody, but did not attenuate the increase in lavage fluid neutrophil numbers and total protein concentration. MAB TF1-1F7 administration reduced the percentage of lung affected by pneumonic lesions from 51.81 % to 10.40% and attenuated intra-alveolar deposition of fibrin, neutrophils, and erythrocytes.

Conclusion

Intra-alveolar fibrin deposition and activation of coagulation in cattle with pneumonic pasteurellosis is, at least in part, mediated by TF.

Clinical Relevance

Treatments that neutralize TF activity may attenuate lung injury in cattle with pneumonic pasteurellosis (Am J Vet Res 1997;58:28–33)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine optimal zinc sulfate test solution concentration tor detecting failure ot passive transfer in calves.

Animals

235 calves (1 to 8 days old) from a calf-rearing operation in central Washington state.

Procedure

Zinc sulfate turbidity tests, using 200-, 250-, 300-, 350-, and 400-mg/L test solutions, were performed on calf serum. These increasing concentrations were evaluated for detection of failure of passive transfer Using 1,000 mg of IgG,/dl as the threshold for adequate passive transfer, sensitivity, specificity, and accuracy of classification were determined by comparing the zinc sulfate test results with serum IgG, concentration (mg/dl) measured by radial immunodiffusion.

Results

The 200-mg/L zinc sulfate turbidity test solution was 100% sensitive; however, specificity was only 25 5% Increasing concentrations of zinc sulfate test solution up to 350 mg/L improved specificity with either no change or small decreases in sensitivity.

Conclusion and Clinical Relevance

The endpoint of the traditional 208-mg/L zinc sulfate turbidity test for failure of passive transfer in calves is too high. Increased test solution concentrations improve specificity with only minor adverse effects on sensitivity. (Am J Vet Res 1996;57:1711–1713)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To test the immunocompetence of isogenic families of rainbow trout by measuring their ability to accept or reject skin grafts.

Animals

3 families of isogenic rainbow trout (Oncorhynchus mykiss), produced by mating homozygous females and homozygous males, plus 4 Chinook salmon (O tshawytscha) were used in these experiments.

Procedure

Grafts (allografts, members of the same family; autografts, donor and recipient were the same fish; and xenografts, O tshawytscha as donor) were exchanged. Grafts were applied on day 0 and removed on day 21, placed in neutral-buffered formalin, and embedded in paraffin. Lymphocytes and nuclei were counted in representative stained sections in the epidermis, dermis, and hypodermis. Results were analyzed by univariate analysis, using the Shapiro-Wilk statistic.

Results

Autografts were retained and minimal histologic changes were apparent. Allografts were histologically similar to autografts. Xenografts were rejected.

Conclusions

Results indicate that the immune system of isogenic rainbow trout is unable to distinguish between family members within isogenic families, but that a vigorous response is mounted against Chinook salmon xenografts. The isogenic rainbow trout are immunocompetent with respect to the phenomenon of graft rejection. (Am J Vet Res 1996;57:1576–1579)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To define causes of increased susceptibility to coliform mastitis after parturition.

Animals

12 healthy Holstein cows assigned to 2 groups. Group-1 cows (n = 6) had calved between 6 and 10 days earlier. Group-2 cows (n = 6) were in midlactation.

Procedure

Cows from each group were paired and challenge exposed with Escherichia coli in 1 mammary gland. Mastitis severity was determined by bacterial concentration in milk, pyrexia, and milk production. Measures of host defense were neutrophil chemotaxis, adhesion molecule expression, leukocyte recruitment, and cytokine production.

Results

After challenge exposure, group-1 cows had more rapid E coli growth, higher peak bacterial concentration, and higher fever. Leukocyte recruitment was poor in 1 group-1 cow that had peracute mastitis. In contrast, leukocyte recruitment in 5 other group-1 cows began sooner than that in group-2 cows. In these group-1 cows, prechallenge-exposure milk somatic cell counts (SCC) were significantly lower than those in group-2 cows. Pre-challenge-exposure SCC were correlated to stimulated CD18 expression (R2 = 0.79), and both measures correlated inversely with bacterial growth rate (R2 = -0.75). Values for tumor necrosis factor α, interleukin 1, and interleukin 8 in group-1 cows after challenge exposure were greater than or equal to those in group-2 cows.

Conclusions

Weak leukocyte recruitment to the mammary gland is associated with increased severity of coliform mastitis. Impaired production of cytokines measured is not a cause of increased susceptibility to coliform mastitis in early lactation.

Clinical Relevance

Low milk SCC after calving may increase susceptibility to severe coliform mastitis. (Am J Vet Res 1996;57:1569–1575)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine the effect of mold extracts with high protease activity on the biological activity of allergenic tree, grass, and weed extracts, using in vivo and in vitro methods, in atopic dogs.

Animals

15 dogs with history and clinical signs of atopy. All dogs had strong positive reactions (3+ or 4+) to 1 or more preselected allergens and negative reactions (0) to molds.

Procedure

Mold extracts and saline solution were coincubated separately with tree, grass, and weed pollen extracts at 4 C for 30 and 180 days. Skin end-point titration (30-day incubation) and ELISA inhibition (30- and 180- day incubations) tests were performed on all samples. The biological activity of pollen extracts coincubated with mold extracts was compared with that of pollen extracts coincubated with saline solution.

Results

In the skin end-point titration test, weed pollen extracts coincubated with a mixed mold extract lost a statistically significant amount of biological activity, compared with saline coincubated controls. In the ELISA inhibition test, grass and weed pollen extracts incubated with a mixed mold extract lost a significant amount of biological activity, compared with saline coincubated controls. A significant correlation in the measurement of biological activity was found between a loss of end-point dilution in the skin end-point titration test and a decrease in relative potency, as measured by the ELISA inhibition test for allergenic grass and weed extracts.

Conclusion and Clinical Relevance

Mold proteases can decrease the biological activity of certain grass and weed pollen extracts when coincubated in the same vial for 30 days. Separation of mold and pollen extracts, when preparing immunotherapy vaccines, may help prevent loss of pollen extract potency and increase the vaccine’s stability and efficacy. (Am J Vet Res 1996;57:1447-1452)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To study the effects of oral administration of bovine lactoferrin (LF) on intractable stomatitis in feline immunodeficiency virus (FlV)-positive and FIV-negative cats, and phagocytosis of neutrophils in healthy and ill cats, simultaneously.

Animals

7 ill cats with diagnosis of intractable stomatitis (4 FIV positive and 3 FIV negative) and 7 healthy, FIV-negative cats.

Procedure

LF (40 mg/kg of body weight) was applied topically to the oral mucosa of cats with intractable stomatitis daily for 14 days and improvement of clinical signs of disease (pain-related response, salivation, appetite, and oral inflammation), expressed by scoring from 1 to 4, were evaluated. Assay of neutrophil phagocytosis was examined before and 2 weeks after starting LF treatment, using nonopsonized hydrophilic polymer particles (2 μm).

Results

Oral administration of LF improved intractable stomatitis in all 4 respects. Phagocytic activity of neutro-phils increased after LF treatment. This effect was observed in healthy and ill (FIV positive and FIV negative) cats.

Conclusion and Clinical Relevance

Oral administration of LF improved intractable stomatitis and concurrently enhanced the host defense system. Topical application of LF to oral mucous membrane is useful as a treatment for intractable stomatitis even in FIV-positive cats. (Am J Vet Res 1996;57:1443-1446)

Free access
in American Journal of Veterinary Research