Embryonating eggs were inoculated with filtered porcine ileal mucosa containing intracellular curved rods (ICR) and incubated for 4 to 6 days. Three of 12 pigs given the eggs per os developed microscopic lesions of proliferative enteritis (PE). Nonchallenge-exposed control pigs did not develop lesions of PE. Four of six positive control pigs given ileal mucosa from pigs with PE also developed microscopic lesions of PE. All of the PE lesions were found in pigs necropsied 10 to 29 days after challenge exposure. None of the swine in the study had clinical signs or gross lesions of PE. Campylobacter spp were isolated from pigs with and without exposure to the ileal mucosa from pigs with PE. There was no relationship between Campylobacter spp isolation and development of lesions. Deoxyribonucleic acids extracted from embryonating chicken eggs injected with the equivalent of 0.5 mg of mucosal lesions and incubated for 4 days hybridized to a DNA probe specific for the ICR whereas DNA extracted from 1.5 mg of mucosal homogenates of the same proliferative tissue did not hybridize with the same probe. Results of these experiments indicated that ICR injected into eggs remained infective for pigs and suggest replication of ICR in the first-passage eggs.

Naturally acquired turbinate atrophy in rabbits was associated with Pasteurella multocida infection. Several in vitro and in vivo studies were conducted to document toxin production from P. multocida isolates and to determine the relation of toxin to atrophic rhinitis in rabbits. Ten isolates of P. multocida serotype A:12 were obtained from adult New Zealand White rabbits with noninduced atrophic rhinitis. Specific-pathogen-free rabbits inoculated intranasally with isolates of P. multocida developed rhinitis and turbinate atrophy. However, inoculation with filtrates of the same bacteria failed to induce turbinate atrophy. Cytotoxicity was observed in assays, using bovine embryonic turbinate cell cultures with extracts of P. multocida, but not in agar overlay cytotoxicity assays, using bovine embryonic turbinate, bovine embryonic lung, or Vero cell cultures, or in a sandwich ELISA, using monoclonal antibodies to purified P. multocida toxin. Thus, turbinate atrophy was experimentally reproduced in rabbits with isolates of P. multocida, but toxin was only detected in vitro by cell culture assay of P. multocida extracts.

To investigate the determinants of glomerular ultrafiltration, renal micropuncture studies were performed in 9 cats. Mean single nephron glomerular filtration rate (SNGFR), directly measured in outer cortical nephrons, was 29.4 +/- 3.0 nl/min. This was similar to the estimated value for SNGFR (31.3 +/- 4.6 nl/min) obtained by dividing left kidney total glomerular filtration rate (1.41 +/- 0.12 ml/min/kg of body weight) by left glomerular count (175,200 +/- 13,600 glomeruli/kidney). In micropuncture studies performed at mean renal perfusion pressure of 101.3 +/-1.0 mm of Hg, the glomerular capillary hydrostatic pressure was 58.0 +/- 1.4 mm of Hg. The glomerular transcapillary hydrostatic pressure gradient (40.0 +/- 1.8 mm of Hg) exceeded colloid osmotic pressure at the efferent end of the glomerular capillaries (28.4 +/- 2.1 mm of Hg) in all cats studied, indicating existence of positive effective filtration pressure throughout the glomerular capillary bed. These results indicate that glomerular capillary pressure is sufficiently high to prevent forces from reaching filtration pressure equilibrium in feline outer cortical nephrons. Thus, the value of SNGFR in feline nephrons depends on the glomerular transcapillary hydrostatic pressure gradient and the glomerular ultrafiltration coefficient.

Immunoelectrophoresis and single radial immunodiffusion were used to identify and measure tear immunoglobulin concentrations in 50 healthy dogs. Immunoglobulin A and IgG were detected in all samples analyzed, whereas IgM was not detected in any sample. Mean IgA concentration was 25.28 +/- 1.9 mg/dl, adult dogs (> 18 months) having significantly higher mean value. The IgA concentration related to age had significant (P < 0.006) positive correlation; mean IgG concentration was 23.10 +/- 1.72 mg/dl. Linear correlation analysis revealed significant (P < 0.0007) correlation coefficient between tear total protein and IgA concentrations. The IgA and IgG concentrations also were significantly (P < 0.0001) correlated when expressed as milligrams per 100 mg of protein. Relation with sex was not established for either immunoglobulin.

Reliable capacitation of equine spermatozoa has been a major obstacle in the development of equine in vitro fertilization. Experiments were done to compare in vitro capacitation of equine spermatozoa by use of heparin/caffeine, calcium ionophore, uterine tube epithelial cell (UTEC)-conditioned medium, and direct culturing of spermatozoa with UTEC (coculturing). Capacitation-like changes, as determined by chlortetracycline membrane staining patterns, developed with UTEC-conditioned medium and coculturing, equivalent to that with calcium ionophore. Both of these treatments induced more (P < 0.05) capacitation-like changes than did the control, a modified Tyrode's medium. More (P < 0.05) spermatozoa were viable after 24 hours of UTEC coculturing than in the control incubation.

Stimulation of alpha 2 adrenergic receptors inhibits colonic motility and may constrict some peripheral vascular beds. Endotoxemia elicits release of sympathetic neurotransmitters and increases sympathetic nerve activity, which may result in stimulation of alpha 2 adrenergic receptors. The objective of this study was to determine whether blockade of alpha 2 adrenergic receptors would restore cecal motility and blood flow during endotoxemia in horses. Strain-gauge force transducers and ultrasonic flow probes were used to measure cecal and colonic mechanical activity and lateral cecal arterial blood flow. Intravenous infusion of endotoxin (cumulative dose of 0.03 mg/kg) significantly decreased cecal and right ventral colon contractile activity and lateral cecal arterial blood flow. Slow IV infusion of yohimbine (cumulative dose of 75 micrograms/kg) significantly attenuated those effects of endotoxin. On the basis of our findings, we concluded that endotoxemia causes cecal and proximal colonic ileus and cecal hypoperfusion via a mechanism that involves alpha 2 adrenergic receptors.

Intragastric pH monitoring was investigated in ponies. In cadaver stomachs, close contact with the mucosa led to high pH readings if nonweighted electrodes were used. However, pH recorded by weighted electrodes was markedly less affected by mucosal contact (P < 0.001). The latter were used for subsequent trials. In vivo, high correlations were found between pH recorded by weighted electrodes with or without a wire guard to prevent mucosal contact (correlation, r = 0.866; P < 0.001). Readings from each correlated well with those from simultaneous gastric aspirates (r = 0.774 and r = 0.807, respectively; P < 0.001 for both correlations). Plain electrodes recorded more highly variable (temporally heterogeneous) pH than did guarded electrodes. In vitro, trials using equine gastric fluid indicated that this resulted from greater responsiveness of the plain electrode. In vivo, episodes of nearly neutral pH were a common feature, and high pH correlated with intensely yellow-green, neutral fluid in the stomach (rank correlation, p = 0.626; P < 0.01). Concentration of bile acids did not correlate with pH or color score (p = -0.158 and p = 0.076, respectively). Causes of the episodes could include salivary influx, duodenogastric reflux, and variable gastric acid secretion. Pentagastrin infusion (0.6 micrograms/kg of body weight/ h) reduced intragastric pH (P = 0.018), but episodes of neutrality still occurred. Experiments in fed ponies indicated possible existence of a stable pH gradient, from neutral dorsally to heterogeneous and more acidic ventrally. Care was required in the rational choice of summary variables for expression of monitored pH data. Of the frequency distributions of 3 summary variables assessed in this study (mean, median, and percentage of data > pH 4), only that of the mean approached normality. Thus, use of the mean may allow analysis by parametric statistical methods. Intragastric pH monitoring was found to be a useful technique. Episodes of increased pH were often identified. These may represent episodic duodenogastric reflux.

The role of interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor a during endotoxin-induced mastitis in cows was characterized. Six cows had 10 microgram of Escherichia coli lipopolysaccharide infused into 1 mammary gland. Three other cows served as nontreated controls. Within 1.5 to 2.5 hours after infusion, endotoxin caused obvious edema of the mammary gland and increased serum albumin concentration in milk of infused glands 6 times. Milk somatic cell count began to increase 3 to 5 hours after infusion in all treated glands. At 7 hours after infusion, somatic cell counts were increased > 10 times, compared with counts in milk from control cows. Pyrexia of > 1 C developed in only 1 cow, but all treated cows had serum cortisol concentrations > 50 ng/ml in response to endotoxin treatment. High concentrations of IL-1 (10 to 600 U/ml) and IL-6 (2 to 22 U/ml) were detected in milk of infused glands beginning 2.5 to 4 hours after infusion. Endotoxin did not induce detectable amounts of tumor necrosis factor activity in milk or serum. Swelling and mammary gland permeability changes preceded any detectable increase in IL-1 and IL-6 activity, indicating that these clinical signs of inflammation were not mediated by these cytokines. Systemic responses and the leukocytic influx into endotoxin-infused glands developed after or concurrently with initial increases in IL-1 and IL-6 activities in milk. These results suggested that IL-1 and IL-6 may have a role in mammary gland defenses and in the pathophysiologic changes during endotoxin-induced mastitis.

A specific polymerase chain reaction (PCR) assay was devised, allowing detection of 1 bovine leukemia virus (BLV)-infected cell in 10(4) bovine lymphocytes. The efficacy of field application of the developed method was verified by evaluating the rate of viral transmission to calves from infected cows, whether they have persistent lymphocytosis. With this objective, 43 calves were simultaneously tested at birth and at 6 months of age for viral antibodies in serum and for proviral DNA in lymphocytes. At birth, 36 calves were BLV-negative and 3 were BLV-positive by results of serologic and DNA-based assays. Conversely, results for 4 calves had lack of correlation between the diagnostic methods. In particular, 2 calves were DNA-positive and antibody-negative for BLV and 2 other calves had the opposite test results. At 6 months of age, when the immunologic pattern more closely reflects the status of calves' immune response, independent of maternal antibodies, all calves DNA-negative for BLV at birth (n = 38), were consistently PCR- and antibody-negative for BLV. On the contrary, the cattle DNA-positive for BLV at birth (n = 5), whether seropositive or not, were PCR- and antibody-positive for BLV, at the time of the second screening. Thus, these results indicate reliability of the PCR to diagnose perinatal BLV infection. Furthermore, the observation that all calves found to be infected at birth were born to BLV-positive cows with persistent lymphocytosis, indicates that the persistent lymphocytosis status of the cow may represent a factor associated with BLV infection in utero.

Undifferentiated distal respiratory tract disease (nasal discharge, cough, pneumonia) in foals (1 to 8 months old) is a burdensome economic problem on breeding farms yet, the infective agents associated with these episodes have not been well described. Possible causes of these episodes of illness were investigated by culturing specimens of proximal and distal airways of clinically diseased foals (n = 101), prior to any treatment, for aerobic and anaerobic bacteria and viruses (rhinoviruses, equine arteritis virus, equine herpesvirus subtype 1 [EHV-1], influenza virus, and adenovirus). Pairs of sera (n = 47) were examined for antibodies to influenza A virus, equine subtypes 1 and 2, EHV-1, and adenovirus antigens, and sera obtained from foals during acute infection were examined for antibodies (by agar gel immunodiffusion [AGID]) to equi factor antigens of Rhodococcus equi. Viruses were not isolated from the proximal (swab) or distal (bronchial lavage) airway specimens in foals, and only 2 of 47 randomly selected foals seroconverted to EHV-1. Serotiters to the other viruses were low and frequently decreasing between samples, which was compatible with maternally derived antibody. Streptococcus zooepidemicus was the predominant isolate from bronchial lavage specimens (88/101 cases), accompanied by alpha-hemolytic streptococci (8 cases), Bordetella bronchiseptica (13 cases), Staphylococcus epidermidis (9 cases), and other organisms in lesser frequency. Only Str zooepidemicus was recovered significantly (P < 0.05) more often in cases than in controls. The AGID test was found useful to detect 1/26 with presumed exposure to R equi, but positive tests results did not correspond well with bacterial culture results; positive AGID results were recorded in 34% of culture-negative foals. However, foals from which R equi was isolated were distinctive from the other foals on the basis of fever (> 39 C), lack of nasal discharge, blood neutrophilia and decreased percentage of neutrophils in bronchial lavage fluid samples. Isolation of Str zooepidemicus was significantly (P < 0.01) associated with increasing neutrophil percentage in bronchial lavage fluid. In conclusion, the pathogenic roles of Str zooepidemicus and R equi were established in this group of foals with distal respiratory tract infections by use of clinical, endoscopic, hematologic, and cytologic methods. There was no evidence of a viral cause for these infections, indicating that manifestations of distal respiratory tract infection are attributable to bacterial infection causing inflammation of the airways. Further studies are warranted to pursue more-sensitive methods for detection of viral antigen or antibody in undifferentiated distal respiratory tract disease episodes in foals.