The vasculature of 22 small colons from dead adult ponies was perfused with latex or barium sulphate solution. The vascular anatomy was studied by use of dissection and alkali digestion of the latex specimens and microangiography of the barium sulphate-perfused specimens. The small colon is supplied by the caudal mesentric artery. The left colic artery arises from the caudal mesenteric artery, which then becomes the cranial rectal artery. Branches from the left colic and cranial rectal arteries form anastomosing arcades that become narrower distally along the length of the small colon. From these arcades arise terminal arteries, which enter the small colon wall and give rise to a subserosal, an intermuscular, and a large submucosal plexus, with frequent anastomoses between them. The venous drainage closely parallels the arterial supply, except near to its origin from the portal vein, when the left colic vein and caudal mesentric vein are separate from the corresponding arteries.

Thirty-eight tracheobronchial aspirates (TBA) were collected from twenty 1 to 6-month-old foals, which were free of clinical signs of respiratory tract or other infectious disease. We collected TBA from 9 of the foals 3 times when they were approximately 8, 16, and 24 weeks old. Aspirates were examined cytologically after staining with modified Wright-Giemsa, Gram, toluidine blue, and prussian blue stains. Aerobic bacterial culturing was performed on all aspirates. Of the 20 initial TBA, 4 (20%) were normal cytologically on the basis of previously defined criteria for TBA from clinically normal horses, 6 (30%) had a high percentage of eosinophils (> 5%), 8 (40%) were classified as indicative of subacute inflammation, and 2 (10%) were classified as indicative of acute inflammation. Nine (45%) were positive for mast cells and none were positive for hemosiderin-laden macrophages (hemosiderophages). Of the 9 foals from which samples were collected at 16 and 24 weeks of age, results were similar, except for an increase in the number of TBA classified as indicative of chronic inflammation (33% and 22% respectively) and the number positive for hemosiderophages (33% and 88%, respectively). One TBA was considered nondiagnostic because of pharyngeal contamination. Culturing of 12 of the 37 aspirates (32%) yielded a potential microbial pathogen. Only 2 were positive cultures from the same foal. The following organisms were isolated: beta-hemolytic Streptococci spp (4), Actinobacillus/Pasteurella spp (4), Rhodococcus equi (2), unidentified nonenteric Gram-negative rod (1), and Escherichia coli (1). Thirty-four of the 37 aspirates (92%) yielded light growth of various organisms considered to be nonpathogenic and normal inhabitants of the upper respiratory tract. It was concluded that the presence of inflammatory cells, eosinophils, and mast cells in the tracheobronchial aspirates from clinically normal foals is a common finding. These cytologic findings were consistent in the samples collected from foals at 8, 16, and 24 weeks of age. It was also concluded that bacteria with recognized pathogenicity can be isolated from TBA from clinically normal foals and were most frequently isolated from 1- to 2-month-old foals or those with cytologic evidence of inflammation, even in the absence of clinical signs of respiratory tract disease.

Visual-evoked potentials (VEP) and electroretinograms (ERG) were recorded from 10 normal light-adapted adult dogs, using a 3 X 5 matrix of light-emitting diodes as a stimulator. Visual-evoked potentials were recorded from 4 scalp electrodes overlying cortical areas, whereas electroretinographic activity was recorded by 2 scalp electrodes placed near the eye and by a conjunctivally placed electrode. The waveform of the VEP consisted of 3 major positive waves (P1 through P3), with peak latencies in the 20- to 70-ms range. Waveform reproducibility was assessed by comparing peak latencies from VEP recorded on 2 separate days approximately 1 week apart. The peak latencies for P1 through P3 did not differ (P greater than or equal to 0 .05) between first and second recording sessions. To substantiate the postretinal origin of VEP, recordings were made before and after unilateral optic nerve transsections in 4 dogs. Electroretinograms were also measured before and after surgery to assess the integrity of the retina. Postsurgically, VEP were absent when the eye on the surgically treated side was stimulated. Stimulation of the contralateral eye induced VEP with the same waveform shape, but latencies were slightly prolonged (P less than or equal to 0.05) compared with presurgical recordings. The only effect of optic nerve transsection on the ipsilateral ERG was a prolongation (P less than or equal to 0.05) of the b-wave. However, when postsurgical ERG values were compared with those from the intact side after surgery, there were no differences.

Serum samples obtained from feeder calves before and after entry into the market system (days 0 to 7) were assayed for antibodies to Pasteurella haemolytica biotype A, serotype 1 capsular polysaccharide (CPS) and lipopolysaccharide/outer membrane protein (LPSp) by isotype in a kinetic-augmented, antigen-capture ELSIA. These test results, plus indirect hemagglutination (IHA) antibody titers, and hemolysin-in-gel test (HIGT) findings were compared with clinical performance data during the initial 4 weeks in the feedlot (receiving period). High concentrations of HIGT antibody, at the point of initial assembly of feeder calves at weaning and during the subsequent 7-day marketing period, were associated with freedom from bovine respiratory disease (BRD) during the receiving period. High or rapidly increasing concentrations of anti-CPS IgG1 during the marketing period were also associated with less BRD. However, high concentrations of anti-LPSp IgG1 during the marketing period were associated with increased BRD during the receiving period. There was no correlation between the concentrations of antibody determined by IHA tests early in the marketing period and freedom from BRD during the receiving period. High concentrations of antibody determined by this test at entry into the feedlot (day 7) were associated with a high incidence of BRD. Calves vaccinated with a P haemolytica bacterin had significantly (P less than 0.05) higher HIGT values and concentrations of anti-LPPp IgG1 and IHA antibody than did nonvaccinated calves on entry into the feedlot (day 7). Vaccination appeared to have little effect on the amount of anti-CPS IgG1. Of all the tests used to quantitate antibody, the HIGT correlated best with clinical performance. High concentrations of HIGT antibody during the marketing period predicted freedom from BRD during the receiving period. When calves were vaccinated with tissue culture-derived and conventional P haemolytica bacterins in oil adjuvant at 28-day intervals and tested for antibody responses by isotype on days 0, 28, and 35, there were clear and highly significant increases in anti-LPSp IgG1 activity. Also, the amount of anti-LPSp IgM and the HIGT and IHA antibody titers increased significantly. In all tests, the antibody response was highest to the tissue culture-derived bacterin. High concentrations of HIGT antibody, as found in vaccinated animals, were correlated with resistance to transthoracic inoculation of virulent P haemolytica.

An in vitro method to label equine RBC with technetium 99m was modified to achieve quantitative labeling of cells in concentrated whole blood. After a blood sample was incubated with a reducing agent (stannous citrate), an oxidizing reagent (NaOCl) and a chelating agent (EDTA) were added to inactivate residual Sn2+ in the plasma. This step prevented premature reduction of pertechnetate in plasma. Labeling of RBC from 9 healthy horses, using a standard whole blood protocol, resulted in only moderate labeling efficiency (44 to 85%) and indicated a linear relationship between labeling efficiency and PCV. Effects of increased incubation time, increased incubation temperature, prelabeling sedimentation, and double addition of NaOCl/EDTA were investigated in whole blood from 10 healthy horses. Labeling efficiency was improved by each independent factor and by combination of factors. Highest labeling efficiencies (96 to 97%) were achieved when blood samples were sedimented for 20 minutes before being labeled, regardless of incubation time or incubation temperature. Morphologic features of RBC were unaffected by labeling procedures. In vivo whole blood clearance time for labeled cells was determined in 5 healthy horses. Sedimented blood samples were labeled, using a standard 15-minute incubation time at 20 to 22 C. Mean clearance half-time for 5 horses was approximately 20 hours. More than 95% of 99mTc activity was associated with the cells during the 24 hours after reinjection.

The seroprevalence and seasonal trend of antibody titers against equine monocytic ehrlichiosis (Potomac horse fever) were determined in apparently healthy horses in selected areas of Illinois in 1986. Sera from 1,367 horses (6 months to 29 years old) were evaluated for the presence of antibodies against Ehrlichia risticii with indirect immunofluorescence. The majority (88%) of the horses were Thoroughbred or Standardbred racehorses. The number of horses with antibodies against E risticii was 229/1,367 (16.75%). The titers in these horses ranged from 1:10 to 1:640. As the year progressed, the number of seropositive horses (titers greater than or equal to 1:10) and the magnitude of the titers increased significantly, both reaching a maximum in July and August, respectively (P less than 0.05). A relationship between seropositivity and gender was not detected. In the year prior to sampling, 56.8% of the seropositive horses had not been ill, whereas 0.8% had diarrhea, an episode of acute abdominal pain, or laminitis. It was concluded that a large number of horses in Illinois are exposed to E risticii, that maximal exposure occurs in July, and that the most common form of the disease in Illinois is not associated with clinical signs.

The 51Cr-labeled EDTA was validated as a suitable permeability probe in dogs for measurement of passive, unmediated diffusion across intestinal mucosa via intercellular pathways. The 51Cr-labeled EDTA was stable in aqueous solution and did not bind to biologic tissue and fluids. After incubation of 51Cr-labeled EDTA in isolated jejunal loops, analytic subcellular fractionation of jejunal mucosa on reorientating sucrose-density gradients was performed, and no association of 51Cr-labeled EDTA with particulate intracellular organelles was detected. Intravenously administered 51Cr-labeled EDTA was rapidly and completely excreted in urine. Intestinal permeability to 51Cr-labeled EDTA after oral administration was assessed in healthy dogs. The percentage of the administered dose of 51Cr-labeled EDTA excreted in the urine in 24 hours ranged from 2.3 to 17.6% (median, 13%).

Transrectal ultrasonography was performed on the cranial mesenteric artery and its major branches in 23 conscious adult horses. Ultrasonographically, 25 arterial segments were classified as either normal or abnormal. These ultrasonographic classifications were later compared with the gross and histologic evaluations of each artery following necropsy of each horse. In this study, transrectal ultrasonography as a diagnostic test for verminous arteritis had a 90% sensitivity for detecting normal arteries and an 86% specificity for detecting abnormal arteries, suggesting that ultrasonography may be useful in the antemortem diagnosis of verminous arteritis.

Twelve male cats were fed 2 diets that differed in the source of P. In diet 1 (1.4% P), 62.7% of P originated from poultry, meat, and fish meal, and the remainder from other organic ingredients of food. In diet 2 (1.6% P), 63.5% of P was derived from neutral monobasic/dibasic salts, and the remainder from other organic ingredients of the food. The P intake was nearly the same with both diets, but there was a significant (P less than 0.05) difference between diets in the percentage of ingested P that was excreted in the urine (14.7 +/- 5.3% for diet 1; 34.9 +/- 8.4% for diet 2), and in 6-day urinary P excretion (774 +/- 290 mg for diet 1; 2,004 +/- 556 mg for diet 2). The P concentrations in urine samples obtained by cystocentesis after cats ate were significantly (P less than 0.05) higher when cats were fed diet 2 than when those same cats were fed diet 1. Plasma P concentrations increased after ingestion of diet 2, but were unchanged after ingestion of diet 1. Seemingly, urinary excretion of P was markedly influenced by dietary composition. Diets with the same P content have potential for different biologic effects because of differences in availability of P.

Ten Holstein heifers were fed a selenium-deficient (SeD) diet (0.04 mg of Se/kg on a total ration dry-matter basis) 3 months before calving and throughout their first lactation. A selenium-supplemented (SeS) diet (2 mg of Se/head/d) was fed to a group of 10 heifers. In about the 14th week of lactation, the cows were challenge-exposed to Escherichia coli by administering 15 to 40 colony-forming units (CFU) into 1 mammary gland. Selenium concentration microgram/ml) in blood around the time of challenge exposure was 0.033 +/-0.002 (mean +/- SEM) in SeD and 0.132 /-0.006 in SeS cows. Infections were established in all challenge-exposed quarters. The frequency of quarter atrophy and agalactia, and reduction in whole-udder milk yield in the first 4 days after challenge exposure, were greater (P < 0.05) in the SeD cows. Log10 peak bacterial concentrations in milk were higher (P < 0.05) in SeD (7.63 +/- 0.34 CFU/ml) than in SeS cows (5.57 0.66 CFU/ml). Mean log bacterial concentration was significantly higher (P < 0.05) from 12 to 20 hours after challenge exposure in SeD than in SeS cows. Duration of infection was significantly greater (P < 0.05) in SeD (162.0 +/- 12.0) than in SeS cows (114.4 +/- 18.0 hours). Milk somatic cell counts increased significantly more slowly (P < 0.05) in SeD than in SeS cows from 8 to 16 hours after challenge exposure. Ratios of milk somatic cells to bacteria in milk were significantly lower (P < 0.05) in SeD than in SeS cows at l2 and 16 hours after challenge exposure.