Evaluation of foals for immune deficiency disorders

Currently recognized equine immune deficiency disorders include failure of passive colostral immunoglobulin transfer, combined immunodeficiency, selective IgM deficiency, transient hypogammaglobulinemia, and agammaglobulinemia. Additional equine immune deficiency disorders probably exist. Immune deficiency should be suspected in any horse experiencing persistent or recurrent infections that are not responsive to conventional therapy.     

Evaluation of a turbidimetric immunoassay for measurement of plasma IgG concentration in foals

OBJECTIVE: To validate a turbidimetric immunoassay (TIA) for measurement of plasma IgG concentrations in foals. ANIMALS: 36 foals. PROCEDURES: Blood samples were collected from foals before suckling and at 12 and 24 to 36 hours after birth. Plasma IgG concentrations were determined via a commercial single radial immunodiffusion (RID) assay. By use of goat anti-equine IgG antiserum and a spectrophotometer, a TIA was developed to measure plasma and serum IgG concentrations; the percentage light transmission was calibrated against RID assay-determined IgG concentrations. Assay repeatability and effects of serial dilution, sample type, and ambient temperature on assay results were evaluated. RESULTS: Serial dilution of plasma samples from foals 12 and 24 to 36 hours of age with presuckle plasma yielded percentage light transmission results that were highly inversely correlated (r = -0.95) with IgG concentrations determined via RID assay. Measurements of IgG in plasma and serum samples via TIA did not differ. When samples were assayed multiple times, the coefficient of variation was < 5.0%. Ambient temperature did not affect TIA results. At IgG concentrations of 400 and 800 mg/dL, TIA sensitivity was > 90%; specificity was 99.1% and 70.5%, respectively; and positive and negative predictive values were 98.1% and 71.5%, respectively, and 96.4% and 91.1%, respectively. CONCLUSION AND CLINICAL RELEVANCE: Plasma IgG concentrations in foals determined via the TIA and RID assay were highly correlated. The TIA rapidly yielded quantitative results and would be useful in clinical situations where intervention decisions are time dependent.     

Evaluation of a score designed to predict sepsis in foals

Objective: To evaluate the accuracy of a published score designed to predict sepsis in foals in a clinical setting and to evaluate the association of clinical and clinicopathological variables with sepsis. Design: Observational study. Retrospective for data from 1998. Prospective in 1999–2001. Setting: Foal intensive care unit of a university hospital. Animals: Client‐owned foals of less than 10 days of age, presenting from 1998 to 2001. Interventions: None. Measurements and main results: Data from the history and physical examination, together with admission hematology, biochemistry and arterial blood gas analysis were used to generate the published sepsis scores. The same data were investigated for their statistical relationship with sepsis. The presence or absence of sepsis was determined from blood culture, culture of sites of suspected local infection, clinical course and/or post‐mortem examination. The modified sepsis score was calculated for 168 foals, which were classified as septic (86), non‐septic (45) or not possible to classify (37). The modified sepsis score correctly predicted sepsis in 58 out of 86 foals and non‐sepsis in 34 out of 45 foals, resulting in a sensitivity of 67%, a specificity of 76%, a positive predictive value of 84% and a negative predictive value of 55%. Abnormal neutrophil cytology, an immunoglobulin concentration of less than 400 mg/dl, and low blood glucose concentration had the strongest association with sepsis. Conclusions: The low negative predictive value of the sepsis score limited its clinical utility. The sepsis score should not be used to define sepsis in clinical studies, unless previously validated in the study center.     

Air sampling in the breathing zone of neonatal foals for prediction of subclinical Rhodococcus equi infection

Reasons for performing the study: Disease caused by Rhodococcus equi is a significant burden to the horse breeding industry worldwide. Early detection of rhodococcal pneumonia, albeit important to minimise treatment costs, is difficult because of the insidious nature of the disease and the lack of definitive diagnostic tests. Objectives: To investigate air sampling from the breathing zone of neonatal foals as a predictor of subsequent rhodococcal pneumonia. Methods: Air samples were collected from the breathing zone of 53 neonatal foals (age ≤10 days) and again at the time of routine ultrasonographic screening for R. equi pneumonia (age 1–2 months). Results: Pneumonia was diagnosed ultrasonographically in 23% of foals. Virulent R. equi was detected in air from the breathing zone of 19% of neonatal foals and 45% of foals at age 1–2 months. There was no association between virulent R. equi in the breathing zone of foals and the subsequent ultrasonographic diagnosis of rhodococcal pneumonia. The median concentration of virulent R. equi in the breathing zone of both neonates (0 [range 0–4] colony‐forming units [cfu]/250 l) and older foals (0 [range 0–3] cfu/250 l) was not significantly different from that in background air samples (0 [range 0–6] cfu/250 l). There was no difference in the concentration of virulent R. equi in the breathing zone of older foals that were diagnosed with rhodococcal pneumonia or clinically normal foals. Conclusion: Detection of virulent R. equi in air from the breathing zone was not a positive predictor of rhodococcal pneumonia in foals up to age ≤2 months. Potential relevance: Selective culture of air samples from the breathing zone of young foals is not better at diagnosing rhodococcal pneumonia than early ultrasonographic screening. However, culture of air samples from the breathing zone of older foals remains a useful herd‐based epidemiological tool.     

Evaluation of nasotracheal aspiration as a diagnostic tool for Rhodococcus equi pneumonia in foals

The reliability of preparing bacteriological cultures from nasotracheal aspirates of foals routinely in order to diagnose R. equi pneumonia in foals was studied by isolating Rhodococcus equi from specimens obtained from 96 foals by nasotracheal aspiration with a silicon catheter. Results were compared with specimens obtained from 21 foals by transtracheal aspiration (percutaneous tracheal puncture). These 117 foals showed clinical signs of respiratory tract infection at sampling. R. equi was isolated from 14 of 21 (66.7%) specimens by transtracheal aspiration and from 59 of 96 (61.4%) specimens by nasotracheal aspiration, 649 of 655 isolates (99.1%) from the 73 positive specimens were virulent R. equi, and the culture-positive foals were diagnosed as having R. equi pneumonia. To assess the contamination of aspirates by organisms from the nasopharynx, the results of R. equi isolation from nasal swabs obtained from 56 of the 96 foals were compared to those obtained by nasotracheal aspiration from the same foals. R. equi was isolated from 2 of the 56 nasal swabs: one from a tracheal aspirate was positive, and the other was not. These results suggest that the nasotracheal aspiration technique, which is noninvasive and not associated with complications, could be used as an alternative to the transtracheal aspiration method, especially for the diagnosis of R. equi pneumonia in foals.     

Evaluation of tulathromycin in the treatment of pulmonary abscesses in foals

Tulathromycin is a new injectable macrolide antibiotic used for the treatment of pulmonary diseases of swine and cattle. In this study, 37 foals with sonographic evidence of lung abscesses were treated with tulathromycin (2.5mg/kg intramuscularly [IM] once weekly, group 1) and 33 foals (group 2) with a combination of azithromycin (10mg/kg per os [PO] once daily for the first seven days of therapy, thereafter every other day) and rifampin (10mg/kg PO twice daily). The bacterial aetiological agent was not determined. The foals were only mildly sick and the median number of pulmonary abscesses was 1.4 (group 1) and 1.6 (group 2). Thirty foals in each group were treated without modifying therapy protocols until all clinical signs of disease had subsided. Tulathromycin was administered for a mean of 53 days, and azithromycin/rifampin for 42 days. The following side effects were associated with tulathromycin (279 IM injections): self-limiting diarrhoea in 11 foals; elevated temperature in six foals, and swellings at the injection site in 12 foals. This study provides some evidence that tulathromycin is well tolerated and appears promising for the treatment of pulmonary abscesses in foals.     

Evaluation of laparoscopic adhesiolysis for the treatment of experimentally induced adhesions in pony foals

OBJECTIVE: To assess the efficacy of laparoscopic adhesiolysis in the treatment of experimentally induced adhesions in foals. ANIMALS: 8 healthy pony foals. PROCEDURE: Celiotomy was performed and adhesions created at the jejunoileal junction and at sites 0.5 and 1 m proximal to this junction, using a serosal abrasion method. Ten days after celiotomy, exploratory laparoscopy was performed. Laparoscopic adhesiolysis was performed in the treatment group only (4 foals, randomly selected). Thirty days after the exploratory laparoscopy, a final laparoscopic examination was performed, and the foals were euthanatized. The number and characteristics of abdominal adhesions were recorded during laparoscopy 10 and 30 days after celiotomy and during necropsy. RESULTS: At 30 days after celiotomy, the number of adhesions in the control group was significantly higher than the number in the treatment group. In the control group, all adhesions observed during the exploratory laparoscopy were still evident at the final laparoscopy and necropsy. In the treatment group, adhesions did not form again after separation. During final laparoscopy and necropsy, a focal adhesion between the omentum and site of the initial laparoscope portal was observed in 5 of 8 foals. CONCLUSIONS AND CLINICAL RELEVANCE: The serosal abrasion model is useful for studying abdominal adhesions in foals. Laparoscopic adhesiolysis was an effective technique to break down experimentally induced adhesions in the early maturation stage of formation in pony foals. Studies are required to investigate prevention of de novo adhesions at the laparoscope portal sites.     

Comparison of a quantitative microtiter method, a quantitative automated method, and the plate-count method for determining microbial complement resistance.

A quantitative microtiter method for determining the degree of complement resistance or sensitivity of microorganisms is described. The microtiter method is compared with a quantitative automated system and the standard plate-count technique. Data were accumulated from 30 avian Escherichia coli isolates incubated at 35 C with either chicken plasma or heat-inactivated chicken plasma. Analysis of data generated by the automated system and plate-count techniques resulted in a classification of the microorganisms into three groups: those sensitive to the action of complement; those of intermediate sensitivity to the action of complement; and those resistant to the action of complement. Although the three methods studied did not agree absolutely, there were statistically significant correlations among them.     

Evaluation of the sampling plan for a Salmonella monitoring program for slaughter pigs

In the setting of the Salmonella monitoring programme of the Federal Republic of Germany the sampling plan does not take into account prevalences occuring in reality. Hence, in most farms the testing effort will increase. This particularly applies to pig farms up to 100 fatteners, for which the proportion of animals to be tested is too high. Besides, the threshold values determing the allocation to the three quality categories, less than 20%, 20-40%, and more than 40% Salmonella positive fatteners, are also chosen too high.     

Uroendoscopy. Evaluation of the lower urinary tract.

Recent advances in uroendoscopy have allowed diagnostic evaluation of the lower urinary tract in most of our canine and feline patients. By providing a magnified view of the luminal surfaces of the lower urinary tract, uroendoscopy provides useful diagnostic information that is not readily available even by more invasive techniques.     

Evaluation of sulbactam plus ampicillin for treatment of experimentally induced Klebsiella pneumoniae lung infection in foals.

Efficacy of sulbactam, a beta-lactamase inhibitor, in combination with ampicillin, was evaluated for treatment of experimentally induced pneumonia caused by beta-lactam-resistant Klebsiella pneumoniae. Infection was experimentally induced in 18 healthy weanling foals that were randomly allocated to 3 treatment groups: sulbactam plus ampicillin (S/A, 3.3 and 6.6 mg/kg of body weight, respectively), ampicillin (6.6 mg/kg), or vehicle only. Foals were treated daily for 7 days; the observer was unaware of treatment status. Compared with ampicillin and vehicle, treatment with S/A resulted in a statistically significant (P less than 0.05) decrease in severity of pneumonia, with regard to bronchoalveolar lavage cytologic findings (decreased total cell and neutrophil numbers, and increased lymphocyte numbers) and extent of macroscopic lesions in lung tissue of the noninoculated regions. Marked trends toward improvement of S/A-treated foals were observed for quantitative results of bacteriologic culture of bronchoalveolar lavage fluid samples (P less than 0.07), macroscopic pathologic features of the whole lung (P less than 0.1), and histopathologic variables (P less than 0.07), compared with ampicillin- and vehicle-treated foals. Treatment effects were not observed for radiographic, hematologic, and blood gas abnormalities that resulted from infection. In conclusion, the combination of sulbactam plus ampicillin was found to have synergistic effects in vivo, to reduce the extent and severity of experimentally induced gram-negative lung infection in foals.     

Evaluation of granulocyte transfusion in healthy neonatal pony foals

Granulocyte transfusions (GT), 0.98 X 10(9) neutrophils/kg of body weight, were performed on 7 healthy pony foals between 2 and 7 days old. The mean neutrophil count of the foals was significantly (P less than 0.05) greater than base line (4,830 +/- 1,260/microliter) 1 hour after GT (8,870 +/- 3,350/microliter) and was similar to base line by 15 to 18 hours after GT (6,550 +/- 2,310/microliter). Leukocyte concentrates (LC) used for GT were harvested from clinically normal adult horses by continuous-flow centrifugation leukapheresis (CL), 3 to 6 hours after hydrocortisone sodium succinate was administered to increase the blood neutrophil count. The mean neutrophil count of the LC used for GT was 68,050 +/- 13,990/microliter, and the mean LC volume was 377.4 +/- 79.2 ml (14.82 +/- 3.54 ml/kg). The mean time required to collect the LC used for GT was 232.1 +/- 73.4 minutes. Neutrophils from LC had significantly reduced in vitro stimulated migration to zymosan-activated serum, when compared with peripheral blood neutrophils of the donors (P less than 0.05). Neutrophil phagocytosis and bactericidal capacity were not significantly changed in LC. Mean neutrophil migration indices were not significantly different in foals after GT. Mild depression and transient diarrhea was noticed in 1 foal 30 minutes after the start of the GT. The donor of LC for this foal and 1 other donor experienced depression, piloerection, and muscle tremors during CL, indicating that complement had been activated. Problems were eliminated by the use of new disposable plastic materials for blood processing in each CL procedure.     

Evaluation of intravenous administration of concentrated immunoglobulin G to colostrum-deprived foals.

Ten foals of various breeds were deprived of colostrum from birth to 36 hours of age, then were allotted to 2 groups. Foals of group 1 (n = 6) were given 20 g (200 ml) of purified equine IgG IV in a 10% solution, and foals of group 2 (n = 4) were given 30 g (300 ml) of the same preparation. Total administration time for each 10 g of IgG in 100 ml was approximately 10 minutes. Serum IgG concentration in foals was assessed prior to, between 24 and 48 hours, and at 7 and 14 days after IgG administration. Between 24 and 48 hours after IgG administration, mean serum IgG concentration in group-1 foals was 425 mg/dl (range, 350 to 480 mg/dl). Mean body weight for this group of foals was 50.3 kg (range, 43.3 to 54.7 kg). For group-2 foals, mean serum IgG concentration was 768 mg/dl (range, 640 to 920 mg/dl) between 24 and 48 hours after administration of IgG. Foals of this group had mean body weight of 43.2 kg (range, 36.5 to 47.5 kg). Serum IgG concentration in group-2 foals at 24 to 48 hours was significantly (P = 0.005) greater than that in group-1 foals. Mean total IgG recovery at 24 to 48 hours, calculated on the basis of 94.5 ml of plasma volume/kg of body weight, was approximately 100%. Values of IgG measured in all foals 1 and 2 weeks after administration of the IgG concentrate were equivalent to values expected after normal decay of passively acquired IgG.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of Lactobacillus pentosus WE7 for prevention of diarrhea in neonatal foals

OBJECTIVE: To evaluate the efficacy of Lactobacillus pentosus WE7, an equine-origin organism with potentially beneficial in vitro properties, as a probiotic for prevention of neonatal diarrhea in foals. DESIGN: Randomized controlled clinical trial. ANIMALS: 153 foals. PROCEDURE: Foals were enrolled at 24 to 48 hours of age and randomly assigned to treatment or control groups. The treatment group received approximately 2 x 10(11) CFU of freeze-dried L. pentosus WE7 orally once daily for 7 days, whereas the control group received a placebo. Clinical monitoring was performed for 14 days. RESULTS: Probiotic administration was significantly associated with development of signs of depression, anorexia, and colic and the need for veterinary examination and treatment. Probiotic-treated foals also had more days of diarrhea, compared with the control group, although not significantly. In a multivariate model, probiotic administration was significantly associated with development of diarrhea and diarrhea plus additional clinical abnormalities. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of L. pentosus WE7 did not prevent diarrhea; rather, it was associated with development of diarrhea and, most importantly, development of diarrhea plus additional clinical abnormalities and the need for veterinary intervention. The promising in vitro properties of L. pentosus WE7 were not evident in vivo. Results raise concern about the variety of untested probiotic products that are commercially available. Safety and efficacy testing needs to be performed for all potential equine probiotics.