A Novel Surgical Methodology for Dual Cannula Placement of the Ileum and Cecum in Equids: Assessment of Postoperative Management and Clinical Outcome.

Cecal and ileal cannulations have previously been used to determine equine digestibility and define gastrointestinal physiology. However, research has been limited to specific portions of the equine digestive tract lacking utilization of dual cannulations. The purpose of this study was to develop and implement surgical and preoperative and postoperative procedures for cannulation of dual sections, ileum and cecum, of the equine digestive tract including development of recommendations for addressing postsurgery complications. A total of 8 ponies went through surgical procedures for the placement of a cannula at the ileum and cecum. All ponies awoke from the surgery and stood, but during postsurgical care, complications arisen including increased temperature, dehydration, lameness, herniation, and peritonitis. The survival rate of dual cannulation of the ileum and cecum was 63% of the animals with euthanization attributed to intestinal herniation. This research provides information for the academic community to better plan and implement dual cannulation of equids.

Cardiac findings in Quarter Horses with heritable equine regional dermal asthenia.

OBJECTIVE To compare biomechanical and histologic features of heart valves and echocardiographic findings between Quarter Horses with and without heritable equine regional dermal asthenia (HERDA). DESIGN Prospective case-control study. ANIMALS 41 Quarter Horses. PROCEDURES Ultimate tensile strength (UTS) of aortic and mitral valve leaflets was assessed by biomechanical testing in 5 horses with HERDA and 5 horses without HERDA (controls). Histologic evaluation of aortic and mitral valves was performed for 6 HERDA-affected and 3 control horses. Echocardiography was performed in 14 HERDA-affected and 11 control horses. Biomechanical data and echocardiographic variables of interest were compared between groups by statistical analyses, RESULTS Mean values for mean and maximum UTS of heart valves were significantly lower in HERDA-affected horses than in controls. Blood vessels were identified in aortic valve leaflets of HERDA-affected but not control horses. Most echocardiographic data did not differ between groups. When the statistical model for echocardiographic measures was controlled for body weight, mean and maximum height and width of the aorta at the valve annulus in short-axis images were significantly associated with HERDA status and were smaller for affected horses. CONCLUSIONS AND CLINICAL RELEVANCE Lower UTS of heart valves in HERDA-affected horses, compared with those of control horses, supported that tissues other than skin with high fibrillar collagen content are abnormal in horses with HERDA. Lack of significant differences in most echocardiographic variables between affected and control horses suggested that echocardiography may not be useful to detect a substantial loss of heart valve tensile strength. Further investigation is warranted to confirm these findings. Studies in horses with HERDA may provide insight into cardiac abnormalities in people with collagen disorders.

Stress state and strain rate dependence of the human placenta.

Maternal trauma (MT) in automotive collisions is a source of injury, morbidity, and mortality for both mothers and fetuses. The primary associated pathology is placental abruption in which the placenta detaches from the uterus leading to hemorrhaging and termination of pregnancy. In this study, we focused on the differences in placental tissue response to different stress states (tension, compression, and shear) and different strain rates. Human placentas were obtained (n = 11) for mechanical testing and microstructure analysis. Specimens (n = 4+) were tested in compression, tension, and shear, each at three strain rates (nine testing protocols). Microstructure analysis included scanning electron microscopy, histology, and interrupted mechanical tests to observe tissue response to various loading states. Our data showed the greatest stiffness in tension, followed by compression, and then by shear. The study concludes that mechanical behavior of human placenta tissue (i) has a strong stress state dependence and (ii) behaves in a rate dependent manner in all three stress states, which had previously only been shown in tension. Interrupted mechanical tests revealed differences in the morphological microstructure evolution that was driven by the kinematic constraints from the different loading states. Furthermore, these structure-property data can be used to develop high fidelity constitutive models for MT simulations.

A comparative biomechanical analysis of term fetal membranes in human and domestic species.

OBJECTIVE: The purpose of this study was to biomechanically characterize and compare human, porcine, equine, and ovine fetal membranes. STUDY DESIGN: Noncontact metrology was used for topographic analyses. Uniaxial tensile testing was performed to resolve specific biomechanical values. Puncture force and radial stresses were determined with biaxial puncture testing. Microstructure and surface tortuosity were analyzed histologically. RESULTS: Equine and human membranes sustained larger magnitude loading, but ovine and porcine membranes exhibited stronger material properties. Biaxial puncture validated uniaxial results; human and equine groups accommodated the largest loads but lowest stresses. Equine membranes were mostly vascularized; tortuosity was highest in porcine membranes. Species' gestation length was correlated positively with membrane thickness. CONCLUSION: The anatomy of placentation and length of species gestation show distinct relationships to membrane biomechanics. Unlike other species, human fetal membranes do not compensate for structural weakness with a thicker membrane. This finding may explain the high incidence of preterm premature rupture of membranes in humans.