Evaluation of digital radiographic measurements for the diagnosis of acute laminitis.

Background: Traditional radiographic measurements of distal phalanx (Pd) displacement based on the outer hoof wall are not useful for diagnosis of acute laminitis.

Objectives: We hypothesised that the distance between the inner hoof wall and Pd ('lamellar lucent zone'; LLZ) measured on lateromedial digital radiographs would be increased in horses with acute and subacute laminitis compared with healthy horses.

Study Design: Retrospective cohort study and in vivo experimental study.

The influence of different horseshoes and ground substrates on mid-stance hoof orientation at the walk.

Background: Horseshoes with modified contact surfaces combined with deformable ground substrates are used to change hoof orientation during mid-stance, for example, for therapeutic reasons.

Objectives: To measure the effect of horseshoes and ground substrates on sagittal and transverse plane hoof orientation at mid-stance using a dorsal hoof wall mounted triaxial accelerometer.

Study Design: In vivo experiment, randomised crossover design.

The effect of pre-dosing with metformin on the insulin response to oral sugar in insulin-dysregulated horses.

Background: A single dose of metformin administered 1 h prior to oral glucose challenge was previously shown to reduce insulinaemic responses in horses with experimentally-induced insulin dysregulation (ID). Targeted administration could be useful for controlling post-prandial hyperinsulinaemia in horses with naturally-occurring ID.

Objectives: The objective was to compare the insulinaemic and glycaemic responses to oral sugar testing (OST) performed at different intervals after a single dose of metformin in horses with naturally-occurring ID.

The effects of orally administered trazodone on ambulation and recumbency in healthy horses.

Background: Trazodone, a serotonin receptor antagonist and reuptake inhibitor, might be a useful adjunctive treatment in the initial management of horses with acute laminitis if it minimizes ambulation or encourages recumbency.

Objectives: (1) Evaluate the effects of PO trazodone on ambulatory activity and recumbency in healthy horses; and (2) assess the pharmacokinetics of multiple PO doses of trazodone.

Animals/methods: In a randomized cross-over design, 8 healthy horses received placebo or trazodone at 2 doses (2.

Effect of ambulation following 18F-fluorodeoxyglucose injection on standing positron emission tomography of the healthy equine digit.

Objective: Measure 18F-FDG uptake in digital tissues of healthy horses subjected to different ambulatory conditions between the time of injection and positron emission tomography (PET) scan acquisition.

Animals: 8 healthy adult horses.

Methods: Horses were walked (AMB) or tied in stalls (NONAMB) immediately after injection with ∼1.

Digital lamellar inflammatory signaling in an experimental model of equine preferential weight bearing.

Background: Supporting limb laminitis (SLL) is a complication of severe orthopedic disease in horses and is often life-limiting, yet the pathophysiology remains obscure.

Hypothesis/objectives: To investigate the role of digital lamellar inflammatory signaling in the pathophysiology of SLL using a model of unilateral weight bearing, hypothesizing that there would be evidence of lamellar inflammation in limbs subjected to the model.

Animals: Thirteen healthy adult Standardbred horses were used for this study (11 geldings, 2 mares; mean age 6.

The effect of cyanoacrylate on knot elongation in three sutures used for prosthetic laryngoplasty in the horse.

Objective: This study investigated the elongation following cyclic loading on square knots of 5 USP multifilament long-chain ultra-high molecular weight polyethylene core (UHMWPE), 2 mm woven UHMWPE tape, and 5 USP braided polyester, with and without cyanoacrylate glue.

Study Design: Experimental study.

Sample Population: n = 4.

Evaluation of locking compression plate fixation of the distal phalanx to the hoof wall as a potential therapy for laminitis.

Background: Surgical stabilisation of the distal phalanx (DP) is a potential therapeutic strategy for severe acute laminitis.

Objective: To evaluate the effects of locking compression plate (LCP) fixation of the DP to the dorsal hoof wall.

Study Design: Ex vivo and in vivo experiments.

Effect of a GLP-1 mimetic on the insulin response to oral sugar testing in horses.

Background: Insulin dysregulation (ID) is the most important risk factor for the development of laminitis in horses and therapies to control it are needed.

Hypothesis/objectives: To assess the effects of a single dose of the synthetic GLP-1 analog exenatide on postprandial insulin dynamics. We hypothesized that exenatide would improve insulin sensitivity and lower postprandial blood insulin concentrations.

Treatment of primary hyperparathyroidism in a Miniature Horse using chemical ablation of abnormal parathyroid tissue localized by 3-phase computed tomography.

A 15-year-old Miniature Horse mare with persistently increased plasma calcium (total and ionized) and serum parathyroid hormone concentrations was presented for suspected primary hyperparathyroidism. Ultrasonography of the thyroid region identified an enlarged heterogeneous mass axial to the right thyroid lobe suggestive of an enlarged parathyroid gland, which was further confirmed using sestamibi nuclear scintigraphy and 3-phase computed tomography. Percutaneous ultrasound-guided ethanol ablation of the mass, a method not previously described in the horse, was performed under general anesthesia resulting in rapid normalization of plasma ionized calcium and serum parathyroid hormone concentrations.

Supporting Limb Laminitis.

Supporting limb laminitis (SLL) is a relatively frequent complication of painful limb conditions that alter normal weight-bearing patterns in horses. New evidence suggests that a lack of limb load cycling activity (normally associated with ambulation) interferes with normal perfusion of the lamellae in these cases, resulting in ischemia and dysfunction/death of cells critical to the mechanical function of the lamellae. Excessive weight-bearing load drives the progression to overt acute laminitis in the supporting limb.

Continuous digital hypothermia reduces expression of keratin 17 and 1L-17A inflammatory pathway mediators in equine laminitis induced by hyperinsulinemia.

The euglycemic hyperinsulinemic clamp model (EHC) of equine endocrinopathic laminitis induces rapid loss of lamellar tissue integrity, disrupts keratinocyte functions, and induces inflammation similar to natural disease. Continuous digital hypothermia (CDH) blocks tissue damage in this experimental model, allowing identification of specific genes or molecular pathways contributing to disease initiation or early progression. Archived lamellar tissues (8 horses, 48 h EHC treatment, including CDH-treated front limbs) were used to measure relative expression levels of genes encoding keratin 17 (KRT17), a stress-induced intermediate filament protein, and genes upregulated downstream of keratin 17 and/or interleukin 17A (IL-17A), as mediators of inflammation.

Plasma amino acid concentrations during experimental hyperinsulinemia in 2 laminitis models.

Background: Endocrinopathic laminitis develops in association with insulin dysregulation, but the role of insulin in the pathogenesis remains unclear. Hyperinsulinemia can cause hypoaminoacidemia, which is associated with integumentary lesions in other species and therefore warrants investigation as a potential mechanism in laminitis.

Objective: Evaluate plasma amino acid concentrations in the euglycemic-hyperinsulinemic clamp (EHC) and prolonged glucose infusion (PGI) laminitis models.

The effect of regional hypothermia on mechanical nociceptive thresholds in the equine distal forelimb.

Regional hypothermia has shown promise as analgesic in horses when used to manage painful conditions of the distal limb such as laminitis. In this prospective study, the analgesic effects of regional hypothermia were assessed using mechanical nociceptive thresholds during distal limb cooling. The study population consisted of eight healthy adult Standardbred horses, selected from a teaching herd.

Lamellar perfusion and energy metabolism in a preferential weight bearing model.

Background: Supporting limb laminitis (SLL) is suspected to be caused by lamellar ischaemia as a consequence of increased mechanical load.

Objectives: Examine the effects of prolonged preferential weight bearing (PWB) on lamellar perfusion and metabolism.

Study Design: In vivo experiment.

Effect of digital hypothermia on lamellar inflammatory signaling in the euglycemic hyperinsulinemic clamp laminitis model.

Background: Continuous digital hypothermia (CDH) prevents lamellar failure in the euglycemic hyperinsulinemic clamp (EHC) model of laminitis, but the protective mechanisms are unclear.

Hypothesis/objectives: To determine if CDH inhibits lamellar inflammatory signaling in the EHC model of laminitis.

Animals: Eight Standardbred horses.

Lamellar energy metabolism and perfusion in the euglycaemic hyperinsulinaemic clamp model of equine laminitis.

Background: Hyperinsulinaemia is associated with the development of endocrinopathic laminitis; however, the mechanisms remain unclear.

Objectives: Evaluate the effects of hyperinsulinaemia on lamellar energy metabolism and perfusion during laminitis development.

Study Design: In vivo experiment.

Evaluation of the effect of laser salpingopharyngostomy on the guttural pouch environment in horses.

Background: Laser salpingopharyngostomy has been used as an adjunct to primary medical therapy allowing for topical debridement, topical treatment or to potentially alter the guttural pouch environment in horses with guttural pouch disease.

Objectives: To evaluate the effect of a laser salpingopharyngostomy on the guttural pouch environment in healthy horses.

Study Design: Experimental study.

The effect of continuous digital hypothermia on lamellar energy metabolism and perfusion during laminitis development in two experimental models.

Background: Continuous digital hypothermia (CDH) prevents lamellar failure in the euglycaemic hyperinsulinaemic clamp (EHC) and oligofructose (OF) laminitis models, but the mechanisms remain unclear.

Objectives: To evaluate the effects of CDH on lamellar energy metabolism and perfusion in healthy horses and during EHC and OF laminitis models.

Study Design: In vivo experiment.

Influence of digital hypothermia on lamellar events related to IL-6/gp130 signalling in equine sepsis-related laminitis.

Background: Interleukin-6 (IL-6) is consistently increased in the digital lamellae in different studies of sepsis-related laminitis (SRL). IL-6 signalling through the gp130 receptor activates similar signalling (i.e.

Effect of thyrotropin-releasing hormone stimulation testing on the oral sugar test in horses when performed as a combined protocol.

Background: The use of parallel dynamic tests to identify insulin dysregulation (ID) and pituitary pars intermedia dysfunction (PPID) in horses could have better diagnostic utility than measuring baseline hormone concentrations, if the tests do not alter diagnostic interpretation of one another.

Hypothesis: Performing a thyrotropin-releasing hormone (TRH) stimulation test before an oral sugar test (OST) would not affect results of OST.

Animals: Twenty-six healthy university-owned horses.

The relationship between bronchoalveolar lavage fluid cytology and airway hyper-reactivity in a population of Australian horses presented for poor performance.

Objective: To investigate the relationship between bronchoalveolar lavage fluid cytology, particularly mast cells, and airway hyper-reactivity in athletic horses presented for poor performance that included a respiratory tract evaluation in two disparate locations in Australia.

Design: Multi-centre, retrospective and prospective cross-sectional study METHODS: Eighty four adult horses underwent both pulmonary function testing and histamine bronchoprovocation with a commercial flowmetric plethysmography system. A bronchoalveolar lavage was performed four to twelve hours later.