Outcome of late-onset hospital-acquired pneumonia related to causative organism.

Pneumonia caused by Pseudomonas spp. has been associated with an increase in mortality in critical care patients. Previous assessments, however, have failed to compare outcome solely with other pathogens associated with hospital-acquired pneumonia (HAP). We have performed a retrospective review of all critical care patients with late-onset HAP (hospital inpatient stay >72 h at time of diagnosis) due to pure respiratory cultures of Pseudomonas spp., meticillin-resistant Staphylococcus aureus (MRSA) or non-pseudomonal Gram-negative (NPGN) organisms from 1998 to 2007. Casenote review involved assessments of illness severity, clinical pulmonary infection scoring (CPIS), critical care and hospital survival, and critical care length of stay. Out of 252 casenotes, 204 were reviewed. There were 186 treated cases of pneumonia. Ten patients had both pseudomonal and NPGN pneumonias during the same admission and two patients presented with community-acquired infections due to these organisms. These 12 patients were excluded from further analysis. Of the remaining 174 patients, 80 were infected with pseudomonas, 40 with MRSA and 54 had NPGN organisms. The three groups of patients were well-matched, with similar age, sex, CPIS scores, incidence of bacteraemia and Acute Physiology and Chronic Health Evaluation II scores at diagnosis. There were no outcome differences between the groups with respect to hospital and critical care survival and critical care length of stay. In this series, there appears to be no survival disadvantage associated with pseudomonal pneumonia when compared with other hospital-acquired organisms associated with HAP, where disease severity between the groups is similar.

Career racing performance in Thoroughbreds treated with prosthetic laryngoplasty for laryngeal neuropathy: 52 cases (1981-1989).

OBJECTIVE: To compare racing performance before and after prosthetic laryngoplasty for treatment of laryngeal neuropathy in inexperienced and experienced Thoroughbred racehorses. DESIGN: Retrospective study. ANIMALS: 52 Thoroughbred racehorses treated with prosthetic laryngoplasty for laryngeal neuropathy. PROCEDURE: Lifetime race records were analyzed by use of a verified regression model. Individual race records and hospital records were also reviewed. RESULTS: Experienced horses had a decline in performance, as measured by performance index, earnings percentage, and mean prediction error, during the 6-month period before prosthetic laryngoplasty. Performance improved after surgery, relative to performance in 1 to 4 races immediately before surgery, but did not attain previous baseline values for performance index and earnings percentage, although racing speed was restored to baseline values. Factors associated with failure to attain baseline levels of performance included other racing-related injuries and disorders, major complications of surgery, and age. Individually, however, many horses had long and successful careers after surgery. Performance of inexperienced horses after surgery was at least equal to that of experienced horses. CONCLUSIONS AND CLINICAL RELEVANCE: In addition to warning clients of the complications associated with prosthetic laryngoplasty, it may be prudent to provide a guarded prognosis for full restoration of racing performance in older horses, unless they are especially talented and are free of other racing-related problems.

Cimetidine inhibits nitric oxide associated nitrate production in a soft-tissue inflammation model in the horse.

Cimetidine (CIM) is an H2-receptor antagonist that has been used in racehorses in an attempt to reduce the occurrence of stress-related gastric ulceration. It has also been shown to produce several useful effects other than its gastric acid suppression properties. Further, it is a well documented antagonist of cytochrome P-450 (CYP) mediated oxygenation reactions. Nitric oxide (NO), a recently discovered mediator or modifier of numerous physiological functions, is generated by several forms of nitric oxide synthase (NOS), one of which is inducible (iNOS). Inducible NOS, expressed in neutrophils and macrophages as part of the inflammatory response to noxious stimuli, contains both a CYP and a CYP reductase domain. Because of the similarity of structure of iNOS and CYP, it was decided to determine whether CIM could reduce NO production, using a carrageenan inflammation model in the horse. Two experiments were conducted. In Trial 1, six female Thoroughbred horses each had three tissue chambers inserted subcutaneously on the sides of the neck. The study was divided into three treatments: 0.9% NaCl (NaCI), CIM (3 mg/kg), and aminoguanidine (AG; 25 mg/kg), an inhibitor of iNOS. Each mare received three i.v. injections 12 h apart prior to instillation of 1 mL of carrageenan into the test chamber. Blood and tissue chamber fluid (TCF) were collected serially. Concentrations of NO3- (the major metabolite of NO), albumin, total protein, CIM and AG were measured and complete cell counts and differentials were conducted. Trial 2 also used six female Thoroughbred horses implanted with at least two tissue chambers inserted subcutaneously on the sides of the neck. The study was divided into two treatments: NaCl (0.9%) and CIM (6 mg/kg). Each mare received seven i.v. injections of either NaCl or CIM 8 h apart prior to instillation of 1 mL of carrageenan into the test chamber. Blood and TCF were collected serially as before, and analysed for NO3- and CIM content. Areas under the curve (AUC) of the different parameters were calculated for the periods of -1-1, -1-3 and -1-7 days (Trial 1) and -2-1 for Trial 2. Absolute values were also compared at 4, 8 and 12 h postcarrageenan. Saline treatment did not reduce the elevated concentrations of NO3- in either plasma or TCF. Plasma, test chamber and control chamber NO3-concentrations rose from 0 to 12 h, and were very similar in all three sampled fluids. Cimetidine significantly (P< or =0.05) decreased NO3- production in plasma over the periods of -1-1, -1-3, and -1-7 days post inflammation when compared to NaCl treatment in Trial 1. Aminoguanidine and CIM decreased NO3-production in TCF for the periods -1-1, 1-3, and -1-7 days post inflammation in Trial 1 and -2-1 for Trial 2. Both CIM and AG also significantly reduced NO3-concentrations in plasma and TCF at 12 h postinitiation (Trials 1 and 2). Thus CIM, at the doses studied, was capable of reducing NO3- concentrations in this model as effectively as AG, a relatively specific inhibitor of iNOS activity.

Ultrasound-assisted diagnosis of renal dysplasia in a 3-month-old Quarter Horse colt.

A 3-month-old foal was presented for correction of bilateral angular limb deformities. Azotemia was detected as an incidental finding. Small, misshapened, hyperechoic kidneys with decreased corticomedullary demarcation were noted with ultrasonography. Additionally, the internal renal architecture was abnormal in that the intrarenal vessels and distant collecting system were not clearly seen in either kidney. Ultrasound-guided renal biopsy was suggestive of congenital renal dysplasia, which was later confirmed at necropsy. Clinical, sonographic, and pathologic features of equine renal dysplasia are discussed.

Ovarian torsion associated with granulosa-theca cell tumor in a mare.

A 12-year-old Morgan mare was examined because of stallion-like behavior of 45 days' duration. Palpation per rectum and transrectal ultrasonographic examination revealed a large left ovary with multiple cystic areas and crepitus. A granulosa-theca cell tumor was suspected. During hospitalization for further evaluation of the affected ovary, the mare developed signs of abdominal pain. Exploratory surgery revealed a large left ovary, which was black with a necrotic and friable surface, and a 720 degrees clock-wise torsion of the ovarian pedicle. Torsion was corrected, and oophorectomy was performed. The mare recovered satisfactorily from surgery. Histologic diagnosis was granulosatheca cell tumor with marked diffuse necrosis. To our knowledge, torsion of the ovarian pedicle has not been reported in the veterinary literature. However, it is not uncommon in women. Ovarian torsion seems to develop in association with neoplasia, cysts, and ovarian hyperstimulation syndrome. Ovarian torsion should be considered as a differential diagnosis for mares with a known ovarian pathologic change such as neoplasia or abscess if signs of abdominal pain are evident.

Evaluation of an autologous tendon graft repair method for gap healing of the deep digital flexor tendon in horses.

A sutured tenorrhaphy technique that incorporated an autologous tendon graft was compared mechanically and histologically with a sutured tenorrhaphy at 6, 12, and 24 weeks after repair. Tenorrhaphy was performed in the forelimb tendon of the deep digital flexor muscle and the graft was taken from the hindlimb tendon of the lateral digital extensor muscle; one forelimb site included the graft, whereas the other forelimb site was not grafted. Tenotomies were made immediately proximal to the insertion of the accessory ligament into the tendon of the deep digital flexor muscle. Grafted and nongrafted tenorrhaphies were sutured with 2 polydioxanone in a modified double locking-loop pattern. Limbs were supported with a bandage and an extended elevated heel shoe that maintained the dorsal hoof wall angle at 70 degrees to 75 degrees; this support was removed at 12 weeks and dorsal hoof wall angle was maintained at 40 degrees to 45 degrees for the remainder of the study. Gap formation (2.5 +/- .3 cm) was evident at all tenorrhaphy sites at 3 days on ultrasound examination. In grafted repairs, the breaking stress was increased (P < .001) between 6 weeks (2.56 +/- .44 MPa) and 12 weeks (17.69 +/- 7.68 MPa), with grafted tendon having a greater breaking stress than nongrafted tendon (8.77 +/- 2.5 MPa; P < .05). No differences in breaking stress were evident at 24 weeks. At 12 weeks, repair tissue in grafted tendon was histologically more mature, had less cellularity, better fibroblast orientation and more homogeneous collagen matrix than nongrafted tendon. Polydioxanone suture was still evident histologically at 24 weeks and was associated with minimal cellular reaction. Incorporation of an autologous tendon graft improved the mechanical properties and histological quality of the repair tissue in equine flexor tenorrhaphies at 12 weeks but not at 24 weeks after repair.

Characterization of bovine pulmonary and serum antibody responses after parenteral or intrapulmonary vaccination with live Pasteurella haemolytica.

Pulmonary and serum antibody responses were evaluated in eight calves vaccinated [four intrapulmonary-right diaphragmatic lobe (IP) and four subcutaneous (SC)] with Pasteurella haemolytica A1 (Ph-1) impregnated agar beads and eight respective sham-vaccinated calves. Experimental and sham groups were challenged in both diaphragmatic lobes with Ph-1 34-37 d after vaccination (DAV) and necropsied 6 d after challenge (DAC; 40-43 DAV). IgG antibodies contained in fluids from the diaphragmatic lobes of vaccinated calves had different patterns of antigen specificity compared with IgG antibodies in analogous sera. Using ELISA, anti-Ph-1 IgA and IgG antibody concentrations were significantly higher (P < 0.05) in lung lavage fluids from the IP group before and after challenge compared to the SC and sham groups. The IP and SC groups developed IgA, IgG and IgM antibody titers in nonvaccinated lung lobes after vaccination and challenge. The IP and SC groups exhibited significantly (P < 0.05) smaller pulmonary lesions than the sham groups and pulmonary IgG and IgA antibodies were associated with increased protection.

Production and characterization of monospecific adult worm infections of Strongylus vulgaris and Strongylus edentatus in ponies.

Since 1978, 20 surgical implantations of either Strongylus vulgaris or Strongylus edentatus have been performed in our laboratory for the purpose of obtaining single species cultures of these parasites. Following surgical implantation peak EPG values of 13-327 (S. vulgaris) and 363-1284 (S. edentatus) generally occurred during the first 3 weeks post-implantation. Duration of infections was as long as 5 years. Successful outcome of such surgeries appears to be related to the total number of parasites used (> or = 38) and the ratio of female to male worms implanted (1:1 or 2:1).

Systemic and pulmonary antibody responses of calves to Pasteurella haemolytica after intrapulmonary inoculation.

Systemic and pulmonary antibody responses of calves to Pasteurella haemolytica were evaluated by measuring immunoglobulin production in blood for 9 days and in pulmonary lavage fluid for 7 days after intrapulmonary inoculation. Clinical signs, pulmonary lesions, pulmonary and systemic inflammatory response, and amount of antigen in lavage fluid were used to evaluate the response of calves to challenge with P haemolytica. The pulmonary response consisted of production of IgG, IgE, and IgM antibodies to P haemolytica antigens and a 17- to 68-fold increase of cells in lavage fluid 8 hours after inoculation, with a gradual decrease toward normal. Antibodies of the IgM isotype to P haemolytica were demonstrated as early as 8 hours through 7 days after inoculation in 3 of 3 calves. Of the anti-P haemolytica isotypes, IgM was found in the highest concentration. In all of the inoculated calves, IgE was found 1 to 2 days after inoculation, and IgG was found in 2 of 3 inoculated calves from day 1 through 7 after inoculation. Detection of IgG correlated with smaller pulmonary lesions. Immunoglobulin A was not detected in lavage fluid. Serum was evaluated for IgG and IgM antibody response to P haemolytica. Specific IgM was detectable 5 days after inoculation, and IgG was detectable 7 days after inoculation. Pasteurella haemolytica antigens were not detected in serum or plasma. A transient increase in neutrophil count was found 8 hours after inoculation, with return to baseline values by 24 hours after inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of an indwelling bronchial catheter model of bovine pneumonic pasteurellosis for evaluation of therapeutic efficacy of various compounds.

A model of bovine pneumonic pasteurellosis, using an indwelling bronchial catheter for inoculation and subsequent lavage of a single main stem bronchus of the lung, was evaluated in a preliminary efficacy trial of an experimental therapeutic compound. Inoculation of 10(7) Pasteurella haemolytica organisms into the bronchus consistently induced a focal pneumonic lesion with typical morphology of pneumonic pasteurellosis in the left or right caudal lung lobe. The experimental treatment caused significant (P less than 0.05) reduction in lung lesion volume, compared with that of a saline-treated control. It also caused significant (P less than 0.05) reduction in lavage fluid bacterial counts at 48 hours after inoculation, compared with counts in the controls. The inflammatory cell count and the percentage of neutrophils increased markedly in lavage fluids 8 hours after inoculation, but differences were not detected between treatments. Significant differences between treatments were not found in clinical signs, rectal temperature, or histologic changes. This model appears to be a sensitive indicator of treatment efficacy and has the advantage over previous models of pneumonic pasteurellosis of allowing sequential monitoring of the primary lesion site.

Hypoglycemia and hepatic ischemic necrosis after small intestinal incarceration through the epiploic foramen in a horse.

A 16-year-old stallion was presented to the Louisiana State University Veterinary Teaching Hospital for evaluation of acute abdominal pain. Physical examination and diagnostic procedures indicated a strangulating obstruction of the small intestine. At exploratory celiotomy, a strangulating incarceration of the jejunum through the epiploic foramen was found. The incarcerated small intestine was reduced, then resection of the nonviable bowel and anastomosis performed. After surgery, the horse exhibited clinical signs and laboratory findings associated with hypoglycemia and died in spite of emergency treatment. On post-mortem examination, a large thrombus was present in the portal vein at the level of the epiploic foramen and the liver had multiple large infarcted areas. The post-operative signs of hypoglycemia and necropsy findings of widespread hepatic ischemic necrosis are complications of epiploic foramen incarceration of the small intestine not previously reported and may in part explain the high mortality rate described for this lesion.

Immune responses of pony foals during repeated infections of Strongylus vulgaris and regular ivermectin treatments.

Ten helminth-free pony foals divided into three groups were used in this study. Eight foals were each experimentally infected per os with 50 Strongylus vulgaris infective larvae weekly for 4 weeks, at which time one foal died of acute verminous arteritis. The remaining seven foals subsequently received 50 S. vulgaris infective larvae every 2 weeks for an additional 20 weeks. Four of the infected foals remained untreated (Group 1) and three of the infected foals were given ivermectin at 8, 16 and 24 weeks post initial infection (Group 2). Two foals served as controls (Group 3). Foals in Group 1 developed eosinophilia, which was sustained throughout the course of infection. A mild eosinophilia also developed in Group 2 foals; however, the eosinophil numbers were markedly reduced for 3 weeks after each ivermectin treatment. Only foals in Group 1 developed significant (P less than 0.05) hyperproteinemia, hyperbetaglobulinemia and a reversal of the albumin/globulin (A/G) ratio 4 weeks after initial infection. Significant (P less than 0.05) IgG anti-S. vulgaris ELISA titers developed in foals in Groups 1 and 2 3 weeks after infection and were sustained for the duration of the experiment. Western blot analysis of soluble somatic antigens of S. vulgaris adult female and male worms probed with sera from foals in Groups 1 and 2 revealed only subtle differences between these animals. The blastogenic reactivity of peripheral blood mononuclear cells (PBMC) to phytohemagglutinin and concanavalin A was not significantly different between groups. Peripheral blood mononuclear cells from foals in Groups 1 and 2 developed significant (P less than 0.05) blastogenic reactivity to S. vulgaris soluble adult somatic antigen when examined at 25 weeks after infection. Mesenteric lymph node cells from foals in Group 2, although not statistically significant, were more reactive to antigen than were the mesenteric lymph node cells from foals in Group 1 when examined at 27 weeks after infection. These results suggest that significant alterations in the immune response of ponies to S. vulgaris does not occur after intravascular killing of larvae by ivermectin treatments.

Disruption of the caudal component of the reciprocal apparatus in two horses.

Two horses became acutely lame following a fall during strenuous exercise and were diagnosed as having disruption of the caudal component of the reciprocal apparatus. Clinical signs consisted of lameness of the right pelvic limb, characterized by flexion of the hock and simultaneous extension of the stifle. Radiography revealed an avulsion fracture from the supracondylar tuberosity and fossa of the distal portion of the femur in one horse. Clinical and radiographic findings indicated avulsion of the lateral origin of the gastrocnemius and superficial digital flexor muscles. Treatment consisted of stall rest, limb immobilization, and phenylbutazone administration. One horse recovered to soundness and the other deteriorated and was euthanatized.

Sequential mesenteric arteriography in pony foals during repeated inoculations of Strongylus vulgaris and treatments with ivermectin.

Semiselective mesenteric arteriography was performed at regular intervals (inoculation weeks [IW] 0, 11, 18, and 24) in 9 of 10 pony foals raised to be free of parasites. Fifty infective larvae (L3) of Strongylus vulgaris were administered weekly for 4 weeks, then every 2 weeks through the 20th week. Three ponies were given ivermectin (oral paste, 0.2 mg/kg of body weight) treatment at IW 8, 16 and 24. Four ponies were inoculated, but did not receive ivermectin, and a third group of 2 ponies acted as uninoculated controls. Control ponies did not have gross or arteriographic lesions, whereas the inoculated untreated ponies had gross and progressive arteriographic lesions typical of verminous arteritis. Arteriographic lesions in the ivermectin-treated inoculated ponies were not as severe those in the untreated inoculated group, and there was either a partial resolution or a lack of progression of arteriographic lesions in all treated ponies. One untreated inoculated pony did not have progressive arterial lesions as did the 3 others in the group, and may develop resistance to the parasite.

Effects of repeated Strongylus vulgaris inoculations and concurrent ivermectin treatments on mesenteric arterial lesions in pony foals.

Eight of 10 pony foals reared under helminth-free conditions were inoculated PO with 50 Strongylus vulgaris infective larvae/week for 4 weeks, at which time 1 foal died of acute verminous arteritis. Inoculation of 7 remaining foals continued at 2-week intervals for 20 weeks. Of the 7 foals, 3 were treated with ivermectin (0.2 mg/kg of body weight) in an oral paste formulation at experiment weeks 8, 16, 24; 4 foals were not treated. Two foals were not inoculated or treated and served as controls. After the first ivermectin treatment, ivermectin-treated foals had fewer days (12 +/- 2.9) with rectal temperatures greater than 38.6 C than did nontreated foals (23.3 +/- 3.8). Mean baseline rectal temperatures were 38 +/- 0.2 C. Adverse clinical reactions to ivermectin treatment were not observed in foals. Foals were euthanatized and necropsied 3 weeks after the last ivermectin treatment (week 24). Ivermectin was effective in reducing S vulgaris arterial larval and intestinal adult parasite numbers by 100% in 3 treated foals. Strongylus vulgaris arterial larvae and/or adults were recovered from all 4 nontreated inoculated foals. One nontreated inoculated foal lacked arterial larvae or active arterial lesions, indicating that protective resistance had developed in this individual. Marked gross and histopathologic lesions typical of chronic S vulgaris infection were observed in the 3 nontreated inoculated foals with arterial larvae. Repeated killing of intra-arterial S vulgaris fourth-stage larvae in ivermectin-treated foals did not exacerbate lesions associated with verminous arteritis or induce unique lesions associated with repeated destruction of arterial larvae.(ABSTRACT TRUNCATED AT 250 WORDS)

Protection of yearling ponies against Strongylus vulgaris by foalhood vaccination.

The long-term efficacy of an irradiation attenuated larval (L3) vaccine against Strongylus vulgaris was tested in ponies which were reared on pasture. Prior to foaling, mares were divided into two groups. One group of mares and foals received regular (eight weekly) treatment with ivermectin and the second group remained untreated. Half the foals in each pasture group were vaccinated at eight to ten weeks of age. Foals were weaned at three to four months of age and maintained on separate pastures. At eight to ten months of age, ponies were placed in box stalls and half of each treatment group were challenged with S. vulgaris (5 x 1000 L3). Clinical signs and lesions typical of acute verminous arteritis were found at necropsy in the ivermectin treated non-vaccinated challenged yearlings. Ivermectin treated vaccinated challenged yearlings did not show these clinical signs, had markedly reduced to absent arterial lesions and showed an 89 per cent reduction in arterial larval burdens post mortem. Significant differences in clinical signs, arterial lesions or arterial larval burdens were not seen between vaccinated and non-vaccinated foals reared without benefit of ivermectin treatment.

Characterization of a soft-tissue infection model in the horse and its response to intravenous cephapirin administration.

A soft-tissue infection model was created in eight horses by infecting subcutaneous tissue chambers with Streptococcus zooepidemicus organisms. Responses of the horses to the infections were determined by monitoring changes in the complete blood count and body temperature and by following changes in the cytology and protein content of the tissue chambers. Systemic reactions to the infections included a mild neutrophilia, mild pyrexia and mild anemia. There was a marked influx of neutrophils and protein into the chambers after they were seeded with bacteria and chamber neutrophil viability decreased markedly at the height of the infection. Subsequent to establishing tissue chamber infections four of the horses were treated with intravenous cephapirin t.d. at a dosage of 20 mg/kg for 5 days. Quantitative culturing of tissue chamber fluid was performed to analyze the efficacy of cephapirin therapy. Cephapirin therapy was accompanied by decreases in the systemic neutrophilia, pyrexia, anemia, and chamber bacterial counts. However, cephapirin did not eliminate the infection in any of the chambers. Chamber neutrophil viability was markedly increased during the cephapirin therapy period.