Plasma Procalcitonin Concentration in Healthy Horses and Horses Affected by Systemic Inflammatory Response Syndrome

Background

The diseases most frequent associated with SIRS in adult horses are those involving the gastrointestinal tract. An early diagnosis should be the goal in the management of horses with SIRS.

Objective

The objective of this study was to evaluate the plasma procalcitonin (PCT) concentration in healthy and SIRS horses to assess differences between the two groups.

Animals

Seventy‐eight horses (30 healthy and 48 SIRS).

Methods

Prospective in vivo multicentric study. Horses were classified as SIRS if at least 2 of the following criteria were met: abnormal leukocyte count or distribution, hyperthermia or hypothermia, tachycardia, tachypnea. Healthy horses showed no clinical or laboratory signs of SIRS. Plasma PCT concentrations were measured with a commercial ELISA assay for equine species. Results were expressed as mean±standard deviation. T‐test for unpaired data was performed between healthy and SIRS group. SIRS group was divided in 4 subgroups and t‐test was performed between healthy versus each subgroup.

Results

PCT concentrations in healthy and SIRS horses were 18.28 ± 20.32 and 197.0 ± 117.0 pg/mL, respectively. T‐test showed statistical differences between healthy versus SIRS group and between healthy versus all subgroups.

Conclusions and Clinical Importance

Results showed an increase in PCT concentration in SIRS horses as previously reported in humans and dogs. PCT could be used as a single assay in equine practice for detection of SIRS.     

Accuracy of two commercial enzyme-linked immunosorbent assays for the detection of antibodies to Salmonella spp. in slaughter pigs from Canada

Large discrepancies are usually found when different ELISAs for the diagnosis of pig salmonellosis are compared. Thus, our main goal was to estimate the diagnostic accuracy through Bayesian approaches of two commercial assays (Svanovir™ “test A” and HerdCheck™ “test B”) for the detection of antibodies to Salmonella spp. in slaughter pigs. Previously, we estimated the agreement between both tests and their relative sensitivity (Se) and specificity (Sp) with respect to bacteriology on caecal content and ileocaecal lymph nodes. Test A, at a cut-off OD% ≥20%, indicated higher prevalence than test B (OD% ≥10%) (14.6% vs. 8.6%). Relative Se with respect to overall bacteriology was low (≈30%) and similar for both tests, but the relative Sp was significantly lower for test A compared to B (88% vs. 95%). Both tests failed to detect some pigs infected with Salmonella serogroups B and C₁, which they were supposed to identify. In general, tests showed only fair-to-moderate agreement when they were compared (kappa: 0.41). In the Bayesian models, Se of test A varied between 63% and 77%, while Se of test B was 73%. Sp of A was always lower than that of test B (89% vs. 95%). The implications derived from the use of these imperfect serological tests will have to be accounted for in large-scale Salmonella-control programs.     

Morphology and Morphometry of Seminiferous Tubules in Crioulo Horses

This study aimed to assess the biometrics of the testes and the morphology of the seminiferous tubules of Crioulo horses. We studied 10 sexually mature stallions (3–6 years of age). After orchiectomy, testes were perfused with Karnovsky's solution and then embedded in glycol methacrylate. Testis sections (4 μm) were cut and stained with toluidine blue and a solution of 1% sodium borate. The histological images were digitized, and the morphometric analysis was performed using ImageJ software. The average weight of the stallions was 377.5 kg, and the average weight of both testicles was 162.9 g. The percentage of testicular parenchyma occupied by the seminiferous tubules and the intertubular tissue was 77.97% ± 6.34% and 22.03% ± 6.34%, respectively. The average tubular diameter was 205.00 ± 36.91 μm, whereas the average height of the seminiferous epithelium was 70.56 ± 2.82 μm. Average tubular length per testicle and average tubular length per gram of testicle were 4,085.10 ± 1,170.68 m and 26.09 ± 10.63 m/g, respectively. The characteristics of the eight stages of the seminiferous epithelium cycle were similar to those reported in other horse breeds. We conclude that the morphometry of the seminiferous tubules of Crioulo horse resembles what has been reported in other horse breeds. The volumetric proportion of the seminiferous tubules and the Leydig cells of the Crioulo horse is one of the highest ever reported for stallions.     

Thyroid Function in Anhidrotic Horses

Background: This study was performed to determine whether anhidrotic horses have altered thyroid function compared with horses that sweat normally.
Hypothesis: Anhidrotic horses have normal thyroid function.
Animals: Ten client-owned horses with clinical signs of anhidrosis were paired with 10 horses living in the same environment that had normal sweat production.
Methods: Horses were diagnosed as having normal sweat production or being anhidrotic based on responses to intradermal injections of terbutaline and physiologic responses to lunging exercise. Control horses were selected from the same environment and matched as closely as possible to anhidrotic horses in terms of age, sex, breed, and athletic condition. Thyrotropin-releasing hormone (TRH) stimulation tests were performed in both horses at the same time, once in the summer or fall, and once again in winter.
Results: Anhidrotic horses produced less sweat in response to intradermal injections of terbutaline and exercise than did control horses. They also had greater increases in body temperature and respiratory rate in response to exercise. Resting concentrations of thyroid hormones and thyroid-stimulating hormone (TSH) were not different between anhidrotic and control horses. Thyroid hormone responses to TRH also were not different between the 2 groups of horses. However, anhidrotic horses had a significantly different TSH response to TRH compared with control horses, particularly in the winter.
Conclusions and Clinical Importance: The biologic relevance of the altered TSH response to TRH in anhidrotic horses is uncertain, considering that TSH concentrations remained within previously reported normal ranges and thyroid hormone responses were not different between anhidrotic and control horses.     

Retrospective Identification of Bacterial Isolates From Emergency Laparotomy Surgical Site Infections in Horses

Surgical site infection (SSI) with multiresistant bacteria is an important cause of postoperative morbidity after laparotomy in horses. The objective of this study was to identify bacteria isolates and their antibiotic resistance patterns associated with the development of wound infection in horses after laparotomy. This is a retrospective case series. Medical records of horses that underwent ventral midline exploratory laparotomy in a four-year period at one equine hospital were reviewed. Results of microbiologic culture and susceptibility testing are described. The study group consisted of 183 (100%) horses that recovered from anesthesia after laparotomy. The prevalence of infection was 19% (24/124) after first surgery and 83% (19/23) after relaparotomy. The most common microbial isolates were bacteria of the family Enterobacteriaceae followed by Staphylococcus ssp., Enterococcus ssp., Streptococcus ssp., and Bacteroides ssp. Bacteria from the family Enterobacteriaceae showed the lowest resistance to amphenicols, cephalosporins, and quinolones groups of antibiotics. Coagulase-positive Staphylococci were sensitive to amphenicols and only 33% were resistant to trimethoprim/sulfamethoxazole. The most commonly used perioperative and postoperative antibiotics were gentamicin and amoxicillin. Limitations include poor control over exposure factors, covariates, and potential confounders during the surgery, recovery time, or period of hospitalization; relying on others for accurate outcome assessment and recordkeeping; lack of follow-up information once animals were discharged from the hospital. Despite 5 days of antibiotic prophylaxis, the rate of incisional infection is still high. The most common isolates from SSI belong to the family Enterobacteriaceae and the genus Staphylococcus, which showed high resistance to the antibiotics used before the gastrointestinal surgery.     

Variation of Insulin Sensitivity Estimates in Horses

In the horse, resting insulin concentration (INS), the glucose-to-insulin ratio (G:I), and the reciprocal of the square root of insulin (RISQI = 1/√INS) are commonly used to estimate insulin sensitivity, whereas the modified insulin-to-glucose ratio (MIRG = [800 – 0.30 × (INS -50)²]/(GLU – 30) is used to estimate pancreatic beta-cell responsiveness. Because no estimates of their within-horse variability and repeatability have been reported, the objective of this study was to evaluate the within-horse variation of these estimates. Resting blood samples were obtained from six healthy equids (three geldings, two mares; mean ± SD body weight, 525.0 ± 43.36 kg; mean age, 9.8 ± 8.2 years; and one pony gelding: 293 kg; 12 years) on three consecutive days in week 1 and again in week 2. Samples were collected at 12:00 noon, approximately 6 hours postprandially. Serum insulin and plasma glucose (GLU) concentrations were analyzed and used to calculate G:I, RISQI, and MIRG, as well as the insulin to glucose ratio (I:G). The coefficient of variation was used to determine within-horse variation, and repeatability was determined using the repeatability coefficient (RC; measurements from a single horse should differ less than the RC for 95% of the pairs). The mean coefficients of variation (CVs) for resting GLU, INS, G:I, I:G, MIRG, and RISQI were 5.5%, 33.7%, 36.0%, 31.6%, 22.3%, and 18.6%, respectively. All variables had values that differed more than the RC in at least one horse. These data suggest that care should be taken when interpreting insulin sensitivity estimates from a single blood sample.