A multicenter, matched case-control study of risk factors for equine laminitis

Risk factors for equine laminitis were examined in a prospective case-control study of the 258 cases seen at six collaborating veterinary teaching hospitals over a 32-month period. Case-control pairs were matched on institution, clinician, and season of diagnosis. The 90% of case-control pairs (78 acute, 155 chronic) that had complete data for age, gender, and breed were used in separate conditional logistic-regression models for acute and chronic laminitis. There was an increase in risk for horses with acute laminitis from 5 to 7 years of age (OR 4.7, 95% CI 1.3–16) and from 13 to 31 years of age (OR 3.9, 95% CI 1.3–12) (both compared to <5 years); risk was increased for chronic laminitis from 10 to 14 years (OR 3, 95% CI 1.4–6.8) and from 15 to 38 years (OR 2.9, 95% CI 1.4–6.1) (both compared to <6 years). Mares — but not stallions — were more likely than geldings to develop acute laminitis (OR 2.6, 95% CI 1.1–6.2) and chronic laminitis (OR 2.0, 95% CI 1.1–3.6). In the small acute-laminitis data set, the breed variable was collapsed into three categories: Thoroughbred (THB, reference), the Quarter Horse (QH), and other (non-QH-THB). The non-QH-THB group was at increased risk of acute laminitis (OR 3.8, 95% CI 1.2–11.8). For the seven breed-group categories used in the chronic-laminitis model, however, all non-THB breed groups appeared significantly at risk as compared to the THB, with odds ratios ranging from 3.3 (95% CI 1.3–8.30) for the QH to 9.1 (95% CI 2.1–39.3) for ponies.     

Evaluation of equine breeding farm characteristics as risk factors for development of Rhodococcus equi pneumonia in foals

OBJECTIVE: To identify farm characteristics as risk factors for the development of Rhodococcus equi pneumonia in foals. DESIGN: Prospective matched case-control study. ANIMALS: 2,764 foals on 64 equine breeding farms with 9,991 horses. PROCEDURE: During 1997, participating veterinarians completed paired data collection forms, 1 for a farm with > or = 1 foal with R equi pneumonia and 1 for an unaffected control farm. Matched data were compared by use of conditional logistic regression analysis. RESULTS: Farm characteristics found in bivariate analyses to be associated with increased risk for pneumonia caused by R equi in foals included > 200 farm acres, > or = 60 acres used in the husbandry of horses, > 160 horses, > or = 10 mares housed permanently on the farm (resident mares), > 17 foals, > 0.25 foals/acre, and the presence of transient mares (mares brought temporarily to the farm for breeding or foaling) and their foals. Affected farms were significantly more likely to be > 200 acres in size and have > or = 10 resident dam-foal pairs, whereas control farms were significantly more likely to have > or = 75% of their dam-foal pairs housed permanently on the farm. CONCLUSIONS AND CLINICAL RELEVANCE: Breeding farms with large acreage, a large number of mares and foals, high foal density, and a population of transient mares and foals are at high risk for foals developing pneumonia caused by R equi.     

Factors Associated with Survival in Septicemic Foals: 65 Cases (1988–1995)

In order to identify variables obtained at admission that could be used to predict survival in septicemic foals, medical records of 65 foals diagnosed with septicemia were reviewed. Initially, variables were analyzed independently (univariate analysis) for association with survival. Of the physical examination and historical data examined using univariate analysis, the ability to stand at admission, respiratory rate ≥ 60 breaths per minute (bpm), and normal-appearing mucous membranes were significantly associated with survival. Foals with history of induced parturition were significantly less likely to survive. The following hematologic and serum biochemical variables determined at admission were significantly associated with survival: white blood cell count a 6,000 cells/μL, neutrophil count <4,000 cells/μL, serum albumin concentration <2.2 g/dL, serum glucose concentration <120 mg/ dL, blood pH ≥ 7.35, and positive base excess. The administration of plasma at admission was significantly associated with survival. Stepwise multiple logistic regression analysis was performed to evaluate the association between survival and variables identified as significantly associated with survival in bivariate analysis. The final multivariate model selected included the variables standing, duration of clinical signs (24-hour intervals) prior to admission, respiratory rate a 60 bpm, neutropenia (> 4,000 cells/μL), and neonatal age category. The probability of survival was significantly increased for foals that were standing, had a respiratory rate a 60 bpm, and that had a neutrophil count <4,000 cells/μL at admission. Probability of survival was significantly decreased for foals that had a longer duration of clinical signs prior to admission. For each 24 hours of duration, the estimated risk of death was increased by 5.8-fold.     

Estimating the Sensitivity and Specificity of Real‐Time Quantitative PCR of Fecal Samples for Diagnosis of Rhodococcus equi Pneumonia in Foals

Background

Real‐time, quantitative PCR (qPCR) methods for detecting Rhodococcus equi in feces have been developed as a noninvasive, rapid diagnostic test for R. equi pneumonia, but have not been evaluated in a large population of foals.

Objective

The objective of this study was to evaluate the clinical utility of fecal PCR as a diagnostic test for R. equi pneumonia in foals using receiver operating characteristic (ROC) methods.

Animals

186 foals born in 2011 at an R. equi‐endemic ranch in Texas.

Methods

Fecal samples were collected at the time of onset of clinical signs for pneumonic foals (n = 31). Foals with pneumonia were matched by age and birth date to healthy (n = 31) and subclinical (n = 124) control foals; fecal samples were collected from these controls. DNA was extracted from feces using commercial kits and concentration of virulent R. equi in feces was determined by qPCR.

Results

Concentration of R. equi in feces differed significantly (P < .05) among groups. The area under the ROC curve for fecal qPCR for diagnosis of R. equi pneumonia was 89% (95% CI, 83–99), with a sensitivity of 94% and specificity of 72%.

Conclusions and Clinical Importance

qPCR of feces can be useful as an alternative to tracheobronchial aspiration for the diagnosis of R. equi in foals with clinical signs of pneumonia. Caution should be used in extrapolating results of this study to other populations because fecal concentration of R. equi might vary by geographic location or management practices.     

Comparative Expression Analysis of Gametogenesis‐Associated Genes in Foetal and Adult Bubaline (Bubalus bubalis) Ovaries and Testes

This study was conducted to identify and analyse the expression of gametogenesis‐associated genes and proteins in foetal and adult buffalo gonads of both the sexes. Relative quantification of the genes was determined by qPCR and Western blotting. Immunohistochemistry was also performed for various gametogenesis‐associated proteins in foetal and adult gonads of both the sexes. We observed significantly (p < 0.05) increased expression of primordial germ cell‐specific, meiotic as well as genes associated with oocyte maturation and development in foetal ovaries as compared to the adult ones. However, significantly (p < 0.05) increased expression of proteins associated with oocyte maturation like GDF9 and ZP4 was found in adult ovaries, indicating temporal regulation of mRNA translation during oogenesis. Meiotic genes showed significantly (p < 0.05) increased expression in adult testes as compared to foetal testes and ovaries, indicating onset of meiosis at a later stage in spermatogenesis. In general, the expression of primordial germ cell‐associated as well as meiotic genes was higher in adult testes, indicating the increased biological activity in the organ. Immunohistochemistry revealed localized expression of gametogenesis‐associated proteins in ovarian follicles and seminiferous tubules of testes, while the surrounding somatic tissues were devoid of these proteins. The study gives an understanding of the sequential and temporal events of gene expression as well as mRNA translation during male and female gametogenesis. It could also be concluded that follicles and seminiferous tubules are the functional units of the female and male gonads, respectively, and their function could be enhanced by appropriate chemical and genetic intervention of the somatic tissue immediately surrounding them. This assumes importance in the context that buffalo attains sexual maturity at an older age of 2–3 years and have smaller ovaries with lesser number of primordial follicles in comparison with cattle, which is suggested to be the main reason of their poor breeding performance.     

MAGNETIC RESONANCE IMAGING OF THE BRAIN OF NORMAL NEONATAL FOALS

Magnetic resonance imaging (MRI) was performed on gthe brain of 5 normal, anesthetized, neonatal (age 3-to-6 days) Quarter Horse foals. The objectives of the study were to develop a technique for imaging the brain of neonatal foals, and to ascertain their normal brain anatomy. Interavenous propofol was administered for induction and maintenance of general anesthesia. Using spin echo MR techniques, T1 weighted sagittal and transverse views, and spin density and T2 weighted transverse views were successfully made of each foal. MR images provided excellent visualization of many anatomic struictures of the brain and head. MRI of the bgrain is feasible for selected neonantal equine patients.     

Ultrasonographic characteristics of splenic and hepatic lymphosarcoma in three horses.

Splenic and hepatic ultrasonography were beneficial for diagnosis of lymphosarcoma in 3 horses with anorexia, weight loss, and lethargy. Ultrasonographic abnormalities of the spleen included a large, complex, hypoechoic mass in 1 horse, multiple well-marginated, hypoechoic nodules in 1 horse, and diffuse hyperechogenicity in another horse. Ultrasonographic abnormalities of the liver included a spherical, hypoechoic nodule in 1 horse and diffuse hyperechogenicity in another. Histologic examination of ultrasound-guided biopsy specimens or aspirates revealed lymphosarcoma. Necropsy findings confirmed diagnosis of lymphosarcoma in all horses. Necropsy findings of the liver and spleen correlated well with antemortem ultrasonographic images.