Severe aortic regurgitation due to endocarditis in a horse

A 4-year-old Belgian Warmblood mare was presented because of fever, exercise intolerance, a loud diastolic cardiac murmur and a remarkable bounding pulsation that was palpable all over the body. This bounding pulsation appeared simultaneous with the cardiac contractions. Cardiac ultrasound revealed a vegetation on the aortic valve with severe aortic regurgitation and a second vegetation at the sinus of Valsalva. A reverse flow in the common carotid artery was present during diastole. Left heart catheterization showed left ventricular and aortic pressure curves characteristic of a rather acute development of the lesion. The strong bounding pulsation was caused by severe aortic regurgitation that resulted in a very wide pulse pressure with the occurrence of "Watson's water hammer pulse". Due to the grave prognosis, treatment was not attempted. Necropsy confirmed aortic valve endocarditis

Quantification of left ventricular longitudinal strain, strain rate, velocity and displacement in healthy horses by 2-dimensional speckle tracking

Background: The quantification of equine left ventricular (LV) function is generally limited to short-axis M-mode measurements. However, LV deformation is 3-dimensional (3D) and consists of longitudinal shortening, circumferential shortening, and radial thickening. In human medicine, longitudinal motion is the best marker of subtle myocardial dysfunction. Objectives: To evaluate the feasibility and reliability of 2-dimensional speckle tracking (2DST) for quantifying equine LV longitudinal function. Animals: Ten healthy untrained trotter horses; 9.6 +/- 4.4 years; 509 +/- 58 kg. Methods : Prospective study. Repeated echocardiographic examinations were performed by 2 observers from a modified 4-chamber view. Global, segmental, and averaged peak values and timing of longitudinal strain (SL), strain rate (SrL), velocity (VL), and displacement (DL) were measured in 4 LV wall segments. The inter- and intraobserver within- and between-day variability was assessed by calculating the coefficients of variation for repeated measurements. Results: 2DST analysis was feasible in each exam. The variability of peak systolic values and peak timing was low to moderate, whereas peak diastolic values showed a higher variability. Significant segmental differences were demonstrated. DL and VL presented a prominent base-to-midwall gradient. SL and SrL values were similar in all segments except the basal septal segment, which showed a significantly lower peak SL occurring about 60 ms later compared with the other segments. Conclusions and Clinical Importance 2DST is a reliable technique for measuring systolic LV longitudinal motion in healthy horses. This study provides preliminary reference values, which can be used when evaluating the technique in a clinical setting

Electrocardiography in horses, part 2: how to read the equine ECG

The equine practitioner is faced with a wide variety of dysrhythmias, of which some are physiological. The recording of an exercise electrocardiogram (ECG) can help distinguish between physiological and pathological dysrhythmias, underlining the importance of exercise recordings. The evaluation of an ECG recording should be performed in a highly methodical manner in order to avoid errors. Each P wave should be followed by a QRS complex, and each QRS complex should be preceded by a P wave. The classification of dysrhythmias according to their origin helps to understand the associated changes on the ECG. In this respect, sinoatrial nodal (SA nodal), atrial myocardial, atrioventricular nodal (AV nodal) and ventricular myocardial dysrhythmias can be distinguished. Artefacts on the ECG can lead to misinterpretations. Recording an ECG of good quality is a prerequisite to prevent misinterpretations, but artefacts are almost impossible to avoid when recording during exercise. Changes in P or T waves during exercise also often lead to misinterpretations, however they have no clinical significance

Electrocardiography in horses, part 1: how to make a good recording

Upon auscultation, cardiac dysrhythmias can be suspected, but electrocardiography is the ultimate diagnostic tool. Electrocardiogram (ECG) recording used to be reserved to specialized centers, but nowadays relatively cheap and small recorders are available to the practitioner in the field. ECGs can therefore be recorded ambulatory and during prolonged periods at rest or even during exercise. The know-how of a good quality recording is mandatory for a correct diagnosis. The basic equipment consists of electrodes, a recorder and a way to display the trace. Self-adhesive electrodes should be used, and positioned along the mean electrical axis of the heart. Small recording devices offer the advantage of allowing recordings during exercise. As the electrical impulse spreads through the heart, the ECG trace shows successively a P wave, a QRS complex and a T wave. T-a waves are not always clearly visible in horses. The positioning of the electrodes may differ for ambulatory, exercise or long-term resting recordings. However, as long as the electrodes are positioned along the mean electrical axis, their exact position is not of crucial importance

Ventricular response during lungeing exercise in horses with lone atrial fibrillation

Reasons for performing the study Atrial fibrillation (AF) is the most important dysrhythmia affecting performance in horses and has been associated with incoordination, collapse and sudden death. Limited information is available on ventricular response during exercise in horses with lone AF. Objectives To investigate ventricular response in horses with lone AF during a standardised lungeing exercise test. Methods A modified base-apex electrocardiogram was recorded at rest and during a standardised lungeing exercise test from 43 horses diagnosed with lone AF. During the test horses walked for 7min, trotted for 10min, cantered for 4min, galloped for 1min and recovered for 7min. Results Individual average heart rate during walk ranged from 42 to 175beats/min, during trot from 89 to 207 beats/min, during canter from 141 to 269 beats/min, and during gallop from 191 to 311 beats/min. Individual beat-to-beat maximal heart rate ranged from 248 to 492 beats/min. Ventricular premature depolarisations were present in 81% of the horses: at rest (16%), during exercise (69%), and during recovery (2%). In 33% of the horses, broad QRS complexes with R-on-T morphology were found. Conclusions Exercising horses with lone AF frequently develop disproportionate tachycardia. In addition, QRS broadening and even R-on-T morphology is frequently found. QRS broadening may originate from ventricular ectopic foci or from aberrant intraventricular conduction, for example due to bundle branch block. This might explain the high number of complexes currently classified as ventricular premature depolarisations. Potential relevance Prevalence of QRS broadening and especially R-on-T was very high in horses with AF and was found at low levels of exercise. These dysrhythmias are considered risk factors for the development of ventricular tachycardia and fibrillation and they might explain signs of weakness, collapse or sudden death that have been reported in horses with AF

Postnatal maturation of the glomerular filtration rate in conventional growing piglets as potential juvenile animal model for preclinical pharmaceutical research

Adequate animal models are required to study the preclinical pharmacokinetics (PK), pharmacodynamics (PD) and safety of drugs in the pediatric subpopulation. Over the years, pigs were presented as a potential animal model, since they display a high degree of anatomical and physiological similarities with humans. To assess the suitability of piglets as a preclinical animal model for children, the ontogeny and maturation processes of several organ systems have to be unraveled and compared between both species. The kidneys play a pivotal role in the PK and PD of various drugs, therefore, the glomerular filtration rate (GFR) measured as clearance of endogenous creatinine (Jaffe and enzymatic assay) and exo-iohexol was determined in conventional piglets aging 8 days (n = 16), 4 weeks (n = 8) and 7 weeks (n = 16). The GFR data were normalized to bodyweight (BW), body surface area (BSA) and kidney weight (KW). Normalization to BSA and KW showed an increase in GFR from 46.57 to 100.92 mL/min/m2 and 0.49 to 1.51 mL/min/g KW from 8 days to 7 weeks of age, respectively. Normalization to BW showed a less pronounced increase from 3.55 to 4.31 mL/min/kg. The postnatal development of the GFR was comparable with humans, rendering the piglet a convenient juvenile animal model for studying the PK, PD and safety of drugs in the pediatric subpopulation. Moreover, to facilitate the assessment of the GFR in growing piglets in subsequent studies, a formula was elaborated to estimate the GFR based on plasma creatinine and BW, namely eGFR =1.879 × BW^1.092/Pcr^0.600

Development of an in vivo lipopolysaccharide inflammation model to study the pharmacodynamics of COX-2 inhibitors celecoxib, mavacoxib, and meloxicam in cockatiels (Nymphicus hollandicus)

Nonsteroidal anti-inflammatory drugs (NSAIDs) are used frequently in avian medicine for their antipyretic, analgesic, and anti-inflammatory properties during surgery and for diseases that cause tissue damage and inflammation. NSAIDs inhibit cyclooxygenase (COX) enzymes, which are responsible for the induction of pyresis, pain, and inflammation. In our study, a lipopolysaccharide-induced (LPS) pyresis model was optimized using cockatiels (Nymphicus hollandicus) as subject birds (four males/three females) and validated in two females and one male, characterized by an intravenous bolus injection of LPS (7.5 mg/kg) administered at T-0 and T-24 (24 hours following the first LPS injection). To demonstrate the feasibility of the model to assess pharmacodynamic (PD) parameters of different NSAIDs, mavacoxib 4 mg/kg (four males/four females), celecoxib 10 mg/kg (four males/four females) and meloxicam 1 mg/kg (four males/four females) were evaluated in the model at dosages used frequently in practice. The PD parameters (body temperature, mentation, posture, preference of location in the cage, and prostaglandin E-2 [PGE(2)] plasma concentrations) were determined for 10 hours following the second LPS injection. At the doses evaluated, mavacoxib and celecoxib significantly reduced LPS-induced hypothermia, but had no clear effects on other clinical signs of illness. In contrast, no effect on hypothermia or clinical appearance was observed in the LPS-challenged cockatiels treated with meloxicam. All three NSAIDs were able to inhibit the increase in LPS-induced PGE2 plasma concentrations, yet the effect was most pronounced in the birds treated with meloxicam. Consequently, the presented model opens perspectives for future dose-effect PD studies to optimize analgesic protocols in cockatiels