Successful total hip arthroplasty in a miniature horse.

OBJECTIVE: To describe the surgical treatment, postoperative management, and outcome of a miniature horse undergoing total hip arthroplasty (THA). STUDY DESIGN: Case report. ANIMALS: A 4-year-old miniature horse stallion weighing 85 kg. METHODS: The horse presented with left coxofemoral luxation of ~6 weeks duration. Computed tomography confirmed craniodorsal luxation with marked degenerative changes to the femoral head. The horse underwent THA using cementless press fit implants, including an interlocking lateral bolt for the femoral stem. RESULTS: The horse recovered well from anesthesia but suffered a coma-like episode after returning to a stable. Following treatment of presumed hypovolemia, the horse regained normal mentation and was discharged 24 days after surgery. At reassessment 12 weeks postoperatively, the horse was 2/10 left hind limb lameness at trot with good healing of the surgery site. Five months postoperatively mild (1/10) lameness remained at trot but the horse was able to canter normally on both reins. The horse has since been managed normally with no veterinary treatment required for 32 months postoperatively. CONCLUSION: Total hip arthroplasty is possible in miniature horses weighing up to 85 kg and can result in a good long-term outcome.

Forecasting and modeling of the COVID-19 pandemic in the USA with a timed intervention model.

We propose a novel Timed Intervention S, P, E, I, Q, R, D model for projecting the possible futures of the COVID-19 pandemic in the USA. The proposed model introduces a series of timed interventions that can account for the influence of real time changes in government policy and social norms. We consider three separate types of interventions: (i) Protective interventions: Where population moves from susceptible to protected corresponding to mask mandates, stay-at-home orders and/or social distancing. (ii) Release interventions: Where population moves from protected to susceptible corresponding to social distancing mandates and practices being lifted by policy or pandemic fatigue. (iii) Vaccination interventions: Where population moves from susceptible, protected, and exposed to recovered (meaning immune) corresponding to the mass immunization of the U.S. Population. By treating the pandemic with timed interventions, we are able to model the pandemic extremely effectively, as well as directly predicting the course of the pandemic under differing sets of intervention schedules. We show that without prompt effective protective/vaccination interventions the pandemic will be extended significantly and result in many millions of deaths in the U.S.

CT more accurately detects foreign bodies within the equine foot than MRI or digital radiography.

Identification and characterization of foreign bodies in the distal limb of horses poses a diagnostic challenge. The aims of this prospective experimental cadaver study were to describe the appearance of five foreign body materials within the equine hoof using CT, MRI, and digital radiography (DR) and to compare interrater agreement among three reviewers. Fifty foreign bodies consisting of five materials were implanted at a solar location or a coronary location in 25 equine cadaver feet. The images were reviewed by three equine veterinarians experienced in advanced imaging interpretation, who were blinded to the material of the foreign body. Foreign bodies were graded on visibility and appearance. Sensitivity and specificity were calculated for accurate identification of the different materials. Interrater agreement was assessed using Fleiss' kappa. Computed tomography had higher visibility score, sensitivity/specificity, and interrater agreement for detection of all materials; particularly slate, glass, and dry wood, compared to the other imaging modalities. Soaked wood and plastic had lower sensitivity (31-33%) on CT with a similar attenuation of the two materials. Foreign bodies were often visible on MRI, although with similar appearance and unclear details. On DR, only slate and glass were visible. The interrater agreement for identifying the correct material was almost perfect for slate, glass, and dry wood (κ = 0.92-1.00) and poor for plastic and soaked wood (κ < 0.20) on CT. Interrater agreement was poor for all materials on MRI and DR (κ < 0.20), with the except for fair (κ = 0.28) for slate on DR and moderate (κ = 0.28) for soaked wood on MRI.

Assessment of intrasynovial injection in horses by contrast-enhanced ultrasonography using air bubbles created by agitation of solution.

BACKGROUND: Accuracy of intrasynovial injections can be challenging to assess in a clinical setting in horses. Contrast-enhanced ultrasonography (CEUS) using injectate agitated with air has been used to determine the success rates of synovial injections in human rheumatology. OBJECTIVES: To assess the diagnostic sensitivity and specificity of CEUS and to describe its clinical use. STUDY DESIGNS: Cadaveric study followed by a prospective descriptive observational study. METHODS: Part 1: CEUS was performed following injection of agitated methylene-blue solution targeting 13 different anatomical synovial structures from three equine cadavers. Contrast was seen as hyperechoic dots, patches or lines on ultrasonography. CEUS was classified as positive if contrast was considered to be intrasynovial and negative if contrast was considered to be extrasynovial. A second synoviocentesis was performed to determine if the injection was intrasynovial based on the presence or absence of methylene-blue. Estimates of sensitivity and specificity were calculated. Part 2: CEUS was performed following injection of agitated solutions targeting synovial structures as part of routine investigation and treatment of clinical cases. RESULTS: Part 1: CEUS was correctly classified as positive or negative in all intrasynovial and extrasynovial injections respectively. The sensitivity estimate was 100% (CI 93%-100%) and the specificity estimates was 100% (CI 16%-100%). Part 2: The technique was used safely for 26 injections (14 horses; 19 different synovial structures) administered to localise or treat lameness. Traumatic intersynovial communications or synovial membrane defects were identified using CEUS in 3 horses. MAIN LIMITATIONS: The low number of extrasynovial injections in Part 1 resulted in an imprecise specificity estimate. CONCLUSIONS: In horses, CEUS performed following intended intrasynovial injection can be useful for identifying unsuccessful injections.

Investigation of the efficacy of the GnRH agonist deslorelin in mitigating intraspecific aggression in captive male Amur leopards (Panthera pardus orientalis).

Housing bachelor groups is a necessary aspect of the care and husbandry of non-breeding individuals in zoological collections. Intraspecific aggressive behaviors may occur in this setting despite management strategies designed to mitigate these behaviors. Androgens (including testosterone) are associated with aggression in male species and interventional techniques to alter the animals' physiology to modify aggressive behavior are sometimes required. When agonistic behavior and physical aggression in two mature male Amur leopards housed together at Tayto Park escalated, despite all strategic management involvements, further intervention to moderate aggression was required. The gonadotropin-releasing hormone (GnRH) agonist, deslorelin, has been found to be effective in reducing androgens in domestic and non-domestic carnivores. We hypothesized that deslorelin's suppressive effect on hypothalamic-pituitary-gonadal axis would mitigate intraspecific aggression in two male intact leopards. Behavioral observations were carried out pre- and post-implant implantation of 9.4 mg deslorelin implant. The frequency of agonistic/aggressive behaviors for both leopards declined significantly (p < 0.05), as did marking behaviors post-implantation (p < 0.001). The insertion of deslorelin implants in two male intact leopards demonstrating increased frequency and severity of aggressive behaviors resulted in a reduction of the frequency of these behaviors. Deslorelin implantation should be considered for management of interspecific aggression of intact male leopards in bachelor groups.

Techniques and Indications for Intraoperative Ultrasound in Horses.

OBJECTIVE: To describe our experience using intraoperative ultrasound for various conditions in horses. STUDY DESIGN: Retrospective case series. SAMPLE POPULATION: Horses (n=113). METHODS: Medical records including surgical reports at 2 equine hospitals (2007-2013) were reviewed to identify ultrasound-assisted surgeries. The diagnosis, reasons for using intraoperative ultrasound, the technique employed, and the surgical procedure performed (e.g., synovial endoscopy, cut-down, resection, dissection, curettage, and implant placement/removal) were recorded for each surgery. Intraoperative ultrasound was used to mark the optimal site for skin incision or to guide instrumentation within the tissues. The incision site was marked on the skin with staples. Depth soundings were taken on the ultrasound, using the caliper-measuring tool to facilitate dissection. For each surgery, the primary specialist surgeon (ACVS or ECVS) retrospectively recorded whether intraoperative ultrasound was helpful, unhelpful, or harmful. RESULTS: Intraoperative ultrasound was rated helpful in 105/113 (93%) of surgeries, unhelpful in 7/113 (6%), and harmful in 1/113 (1%) of surgeries. CONCLUSION: Intraoperative ultrasound can be a useful adjunct to surgical techniques for various conditions in horses.

Regulation by interdomain communication of a headful packaging nuclease from bacteriophage T4.

In genome packaging by tailed bacteriophages and herpesviruses, a concatemeric DNA is cut and inserted into an empty procapsid. A series of cuts follow the encapsidation of each unit-length 'headful' genome, but the mechanisms by which cutting is coupled to packaging are not understood. Here we report the first biochemical characterization of a headful nuclease from bacteriophage T4. Our results show that the T4 nuclease, which resides in the C-terminal domain of large 'terminase' gp17, is a weak endonuclease and regulated by a variety of factors; Mg, NaCl, ATP, small terminase gp16 and N-terminal ATPase domain. The small terminase, which stimulates gp17-ATPase, also stimulates nuclease in the presence of ATP but inhibits in the absence of ATP suggesting interdomain crosstalk. Comparison of the 'relaxed' and 'tensed' states of the motor show that a number of basic residues lining the nuclease groove are positioned to interact with DNA in the tensed state but change their positions in the relaxed state. These results suggest that conformational changes in the ATPase center remodel the nuclease center via an interdomain 'communication track'. This might be a common regulatory mechanism for coupling DNA cutting to DNA packaging among the headful packaging nucleases from dsDNA viruses.

Membrane curvature induced by aggregates of LH2s and monomeric LH1s.

The photosynthetic apparatus of purple bacteria is contained within organelles called chromatophores, which form as extensions of the cytoplasmic membrane. The shape of these chromatophores can be spherical (as in Rhodobacter sphaeroides), lamellar (as in Rhodopseudomonas acidophila and Phaeospirillum molischianum), or tubular (as in certain Rb. sphaeroides mutants). Chromatophore shape is thought to be influenced by the integral membrane proteins Light Harvesting Complexes I and II (LH1 and LH2), which pack tightly together in the chromatophore. It has been suggested that the shape of LH2, together with its close packing in the membrane, induces membrane curvature. The mechanism of LH2-induced curvature is explored via molecular dynamics simulations of multiple LH2 complexes in a membrane patch. LH2s from three species-Rb. sphaeroides, Rps. acidophila, and Phsp. molischianum-were simulated in different packing arrangements. In each case, the LH2s pack together and tilt with respect to neighboring LH2s in a way that produces an overall curvature. This curvature appears to be driven by a combination of LH2's shape and electrostatic forces that are modulated by the presence of well-conserved cytoplasmic charged residues, the removal of which inhibits LH2 curvature. The interaction of LH2s and an LH1 monomer is also explored, and it suggests that curvature is diminished by the presence of LH1 monomers. The implications of our results for chromatophore shape are discussed.