Microorganisms from normal eyes of hospitalized and stabled horses were identified, and the frequency of isolation was compared between the 2 groups. Using standard techniques, swab specimens from both eyes of 22 hospitalized horses and both eyes of 18 stabled horses were cultured for aerobic bacteria and fungi. Ninety-six aerobic bacteria and 57 fungi were isolated. The predominant bacterial isolates were gram-positive organisms, most of which belonged to the genera Corynebacterium, Bacillus, Staphylococcus, and Streptomyces. Gram-negative organisms comprised less than one-fourth of the bacterial isolates, with the genera Neisseria, Moraxella, and Acinetobacter being the most commonly isolated. Environmental fungi Cladosporium and Alternaria accounted for half of all fungal isolates. In only 5 horses were fungi isolated without accompanying isolation of bacteria. The frequency of isolation of fungi was higher (P less than 0.01) in stabled horses. For bacteria, the frequency of isolation was higher (P less than 0.08) in male horses. Results of susceptibility testing were recorded as the percentage of all isolates were highly susceptible to a given antimicrobic drug. Bacterial isolates were highly susceptible (greater than or equal to 90%) to neomycin, polymixin B, gentamicin, and chloramphenicol. Overall, filamentous fungi had highest susceptibility to natamycin (97%). Miconazole was highly efficacious (100% susceptibility) against Fusarium and Aspergillus.

In vitro twitch characteristics of the semimembranosus muscle were evaluated in 9 clinically normal horses, in 15 horses with chronic intermittent rhabdomyolysis (CIR) and in 2 horses with myotonia. Effects of phenytoin on in vitro muscle twitch and clinical signs of CIR and myotonia were evaluated in these same horses. Times to 90% relaxation were prolonged in the horses with CIR (mean +/- SEM, 186 +/- 5.9 ms) and in 2 horses with myotonia (197 and 177 ms) compared with those in clinically normal horses (mean +/- SEM, 146 +/- 2.1 ms). Horses with CIR also had significantly (P < 0.05) longer times to 50% relaxation, compared with clinically normal horses. In the group of horses with CIR, Standardbreds had significantly (P < 0.05) longer times to 90% and 50% relaxation, compared with Thoroughbreds. Times to 100% peak tension did not differ among the groups. Administration of phenytoin directly into a muscle preparation bath solution had no effect on muscle twitch properties. After the initial muscle biopsy, phenytoin was administered orally for 7 to 10 days to 4 horses with CIR, 2 myotonic horses, and 2 clinically normal horses before repeat biopsy from the same site in the contralateral semimembranosus muscle. Times to 90% relaxation decreased from 197 and 177 ms to 144 and 126 ms, respectively, in the 2 myotonic horses, from a mean of 192 (+/- 9) ms to 170 (+/- 9) ms in the 4 horses with CIR and remained unchanged (154 and 140 ms before vs 155 and 139 ms after treatment) in the 2 clinically normal horses. Phenytoin treatment of 8 horses with CIR was associated with excellent clinical response in 7; 1 horse became lame, which prevented evaluation of the drug, and the other horse with normal muscle twitch properties continued to have seasonally severe CIR. Of the 9 horses with CIR that were not treated, 4 were lost to evaluation, 3 continued to be affected (but 1 of these often performed well), and 3 were reported to perform satisfactorily. After 10 days of treatment, the 2 myotonic horses had no change in gait or myotonic dimpling and myotonic discharges persisted, although subjectively, they were slightly decreased. Phenytoin appears to be useful clinically for treating horses with CIR.

Normal sensory nerve conduction velocity (SNCV) values in 8 ponies and 8 horses were compared by use of a percutaneous signal-averaging technique. Nerve fibers evaluated included those in the medial and lateral palmar and plantar digital nerves. Mean SNCV values were significantly slower (P < 0.0002) for horses, compared with those values for ponies. Animal height and nerve segment length were inversely related to SNCV consistently. The SNCV values were affected by surface skin temperature by a factor of approximately 1.2 m/s change for 1 degrees C change in temperatures from 35 C. The ability to calculate warning limits to define those SNCV values in normal and abnormal ranges were developed from these data for both ponies and horses.

An indirect immunoperoxidase staining technique was evaluated for detection of Mycoplasma hyopneumoniae in formalin-fixed, paraffin-embedded porcine lung. Lungs from swine with induced (n = 4) or naturally occurring M hyopneumoniae infection (n = 31) were examined grossly, by light and immunofluorescent microscopy, and by an indirect immunoperoxidase test, using antibody raised in swine against M hyopneumoniae as the primary antibody. Organisms stained by the indirect immunoperoxidase method were identified in tissue sections as pleomorphic brown-staining structures corresponding to those observed with immunofluorescence. Mycoplasma hyosynoviae, M hyorhinis, and Acholeplasma laidlawii did not stain with the indirect immunoperoxidase method, using antibody raised against M hyopneumoniae.

Effects of ventriculectomy and prosthetic laryngoplasty on upper airway flow mechanics and blood gas tensions in exercising horses with induced left laryngeal hemiplegia were assessed. Five adult horses were trained to stand, trot (4.5 m/s), and gallop (7.2 m/s) on a treadmill (6.38? incline). Inspiratory and expiratory airflows (VImax, VEmax, respectively) were measured using a 15.2-cm diameter pneumotachograph in a face mask. Inspiratory and expiratory transupper airway pressures (PuI, PuE respectively) were determined as pressure differences between barometric pressure and lateral tracheal pressure. Blood collected from exteriorized carotid arteries was analyzed for PaO2, PaCO2, pH, hemoglobin (Hb) content, and HCO3-values. Heart rate (HR) was determined with an HR monitor. Measurements were made with horses standing, trotting, and galloping before left recurrent laryngeal neurectomy (LRLN; base line), 14 days after LRLN, 30 days after ventriculectomy (44 days after LRLN), and 14 days after prosthetic laryngoplasty (58 days after LRLN). Before LRLN (base line), increasing treadmill speed for horses from standing to the trot and gallop progressively increased HR, respiratory frequency, VImax, VEmax, PuI, PuE, Hb, and PaCO2 values and decreased PaO2 pH, and HCO3- values; inspiratory and expiratory impedances were unchanged. After LRLN, inspiratory impedance and PuI were significantly (P < 0.05) increased in horses at the trot and gallop, and PaCO2 was significantly increased in horses at the gallop. The VImax and respiratory frequency were significantly (P < 0.05) decreased in horses at the gallop. Left recurrent laryngeal neurectomy had no effect on PuE VEmax, HR, PaO2, pH, Hb or expiratory impedance values. Ventriculectomy failed to improve upper airway flow mechanics induced by LRLN, whereas prosthetic laryngoplasty restored upper airway flow mechanics to base-line values.

Four prototype strains of Mycobacterium paratuberculosis contained the type-specific glycopeptidolipid antigen of serovar 8 of the M avium complex. This glycolipid was distinguished by a 4,6-(1'-carboxyethylidene)-3-O-methyl-beta-D-glucopyranosyl terminal unit. Of 59 low-passage, field isolates of M paratuberculosis, 2 contained this antigen, and these 2 isolates were indistinguishable from M avium serovar 8. However, most M paratuberculosis isolates had no characteristic surface glycopeptidolipid. Seemingly, M paratuberculosis, long regarded as a single species and the causative agent of bovine paratuberculosis, is not a homogeneous taxon. Most isolates obtained from infected ruminants may be antigenically defective, variants ofM avium and, thereby, more successful pathogens.

Ninety-nine nonclassical serogroups isolated from newborn pigs with neonatal diarrhea were tested for fimbrial antigens F4(K88), F5(K99), F6(987P), F41, and F165, and for heat-labile enterotoxin, heat-stable enterotoxin a (STa), heat-stable enterotoxin b, verocytotoxin, and cytolethal-distending toxin. Thirty-two strains, belonging mostly to serogroups O64:K"V142,", O9:K103, and O20:K101, were F5-positive and usually produced STa, although 5 strains produced only heat-stable enterotoxin b. Fifteen strains, belonging mostly to serogroups O64:K"V142" and O20:K101, were F41 positive and usually produced STa. Twenty-three strains belonging mostly to serogroups O64:K"V142," O9:K103, and O20:K101, were F6-positive and usually produced STa. Several strains produced more than one fimbrial antigen, either F5 and F41, F5 and F6, F6 and F41, F6 and F165, or F5, F6, F41, and F165. None of the strains produced heat-labile enterotoxin, verocytotoxin, or cytolethal-distending toxin. The indirect immunofluorescence test was much more sensitive than was the slide agglutination test for the detection of each of the fimbrial antigens F5, F6, F41, and F165 on strains grown in vitro. The production of F6 by certain strains for which only a low proportion of cells were F6-positive in vitro as demonstrated by immunofluorescence, was confirmed by experimental infection of newborn pigs.

In the first of 2 separate trials, the efficacy of febantel, given at a dosage of 5 mg/kg of body weight, was assessed in calves with 60-day experimentally induced Bunostomum phlebotomum infection. Ten calves were given febantel paste, and 10 were given the vehicle only. All 20 calves were necropsied 7 days after cessation of treatment. Compared with untreated calves, febantel-treated calves harbored 99.4% fewer nematodes. In the second trial, the efficacy of ivermectin, given as a paste formulation at a dosage of 0.2 mg/kg, was assessed in calves with experimentally induced B phlebotomum infection. Ivermectin was given at 18 (n = 6) and 60 (n = 6) days after infection. At each treatment date, 3 additional calves were given vehicle only. At 67 days after infection, all calves were euthanatized. Efficacies of ivermectin against 18- and 60-day infections were 100 and 99.8%, respectively. Both anthelmintic preparations were easily administered, and adverse reactions were not observed.

Amendments to the Animal Welfare Act (PL 99-198) require that an exercise program for dogs be established by the attending veterinarian. A 6-week study was conducted to determine the effects of a moderate exercise program in purpose-bred Beagles. Sixteen male Beagles (4/group) were maintained as follows: (1) standard cage without exercise; (2) standard cage with individual exercise periods (35 minutes, 3 times/week); (3) large cage without exercise; and (4) standard cage with group-release exercise periods. Blood samples were collected for CBC, serum biochemical analysis including determination of serum cortisol concentration, and immune function (lymphocyte transformation assay). Group-released dogs interacted with each other during most of the exercise time. Fighting in these dogs occurred only during the third week. Dogs had little inclination to exercise when released along into the exercise area. Regardless of the size of the cage, dogs did not exercise unless human beings were present in the room. There were no significant differences in laboratory findings among dogs in the 4 groups. This moderate exercise program had no demonstrable effects. Similarly, continuous cage housing, without a formal exercise program, could not be determined to be detrimental to the physiologic or health status of dogs.

A significant (P less than 0.0001) positive correlation was demonstrated between left ventricular internal chamber dimension in diastole or systole and body weight, body surface area, cycle length, and the square root of cycle length. On the basis of adjusted coefficients of determination, multiple regression analysis, using body weight or body surface area and cycle length or the square root of cycle length, was superior to separate simple regression with these variables in accounting for variations in left ventricular internal chamber dimensions. Shortening fraction had a significant (P less than 0.0001) negative correlation and left ventricular free wall measurements had a significant (P less than 0.0001) positive correlation to body weight and body surface area. For these echocardiographic variables, correlation to the square root of cycle length was insignificant (P greater than 0.05), and a multiple regression model was not helpful in developing confidence intervals. Septal wall measurements were not correlated with body weight, body surface area, cycle length, or the square root of cycle length.