Associations between postrace atrial fibrillation and measures of performance, racing history and airway disease in horses.

BACKGROUND: Atrial fibrillation (AF) is the most common performance limiting arrhythmia in racehorses. High dose exercise and airway disease promote AF in humans. Few studies have investigated epidemiological factors associated with AF in horses. OBJECTIVES: Explore variables relating to performance, exercise volume and postrace endoscopic findings in horses with AF. ANIMALS: A total of 164 horses with poor race performance and postrace AF were compared to 321 horses with poor performance without AF (PP) and 314 horses performing to expectation (TE). METHODS: Horse-level and race-level variables for horses racing in Australia and Hong Kong from 2009 to 2021 were compared using univariable and multivariable logistic regression. Postrace endoscopic exercise-induced pulmonary hemorrhage (EIPH) and tracheal mucus accumulation (TMA) grades for AF and PP horses were compared using chi-squared analysis. RESULTS: Variables that were significant in the multivariable model of AF compared to TE were distance (lengths) behind the winner, (odds ratio [OR]; 95% confidence interval [95% CI], 1.41 [1.32-1.51], P < .0001), cumulative prize money per start before the event (OR [95% CI] 1.02 [1.01-1.03], P = .01) and age (OR [95% CI] 0.72 [0.55-0.92], P = .01). More AF horses had EIPH grade ≥ 3 (23/109; 21.1%) than PP horses (7/213; 3.3%; OR [95%CI] 7.9 [3.3-20.2], P < .0001). CONCLUSIONS AND CLINICAL IMPORTANCE: Acute race performance was substantially impaired by AF but career earnings before the event were not inferior. Exercise volume did not promote AF. Higher grades of EIPH found in AF horses suggests a mechanistic relationship between these conditions.

Electromyography (EMG) Analysis of Multi-Regional Lower Extremity and Trunk Musculature During Sidelying Hip Abduction With Frontal Plane Stabilization.

Sidelying hip abduction (SHA) is a common exercise utilized in rehabilitation to strengthen the gluteus medius (GMed). Alterations in the exercise can produce different patterns of muscular activity. No studies have examined the effect of mechanical pelvic stabilization during SHA. This study enrolled 19 participants (male = 11, female = 8) who performed the same SHA exercise under two randomized conditions: standard and with a mechanical block to prevent frontal-plane movement. Electromyographic amplitudes during exercise were obtained through surface electrodes and compared against maximum voluntary isometric contraction (MVIC) testing: GMed, gluteus maximus, biceps femoris, tensor fascia latae, quadratus lumborum, and vastus lateralis. While no significant differences were found in GMed activity during SHA with or without pelvic stabilization, reduced concomitant activation of other musculature was observed, potentially producing a more isolated exercise for the GMed with less compensatory activity.

Potential blindness from nutritional xerophthalmia in autistic patients.

BACKGROUND: Vitamin A is vital to retinal rod function and epithelial cell differentiation. Although uncommon in the developed world, vitamin A deficiency (VAD) secondary to poor diets or gastrointestinal disease has been reported and can lead to xerophthalmia, which is characterized by night blindness and a spectrum of ocular surface changes. Patients with autism spectrum disorder have been shown to have restrictive diets secondary to sensory issues leading to rejection of foods except for those of certain color or texture. METHODS: We present a case series of 6 pediatric patients with autism who developed varying degrees of xerophthalmia due to VAD, which resulted from restrictive eating. RESULTS: All patients presented with a history of eye irritation that was not relieved by antibiotic or allergy eye drops. Further questioning revealed they had restrictive diets consisting of only or mostly white and tan foods, and serum vitamin A testing confirmed severe VAD. Most stages of xerophthalmia were completely reversed with vitamin A supplementation, but in 2 patients more advanced xerophthalmia resulted in irreversible blindness and ocular damage. CONCLUSIONS: Both pediatricians and pediatric eye care providers must be vigilant for VAD as an etiology of eye irritation, photophobia, or new-onset visual impairment in autistic children. A review of the child's diet must be implemented as a standard part of routine history taken in this vulnerable population. Early identification and vitamin A supplementation can prevent irreversible ocular compromise and vision loss.

The effect of serial administration of bicarbonate on plasma total CO2 concentrations in horses.

The administration of alkalinising agents including bicarbonate is of concern to racing authorities because resultant alkalosis may enhance performance and interfere with the detection of drugs in post-race urine. A threshold for total carbon dioxide (TCO2 ) of 36.0 mmol/L in plasma (with action limit of 37.0 mmol/L) has been set. Serial dosing of sodium bicarbonate has gained popularity in human athletes but has not been studied in horses previously. Sodium bicarbonate (200 g per horse) and 60 g of an electrolyte-vitamin complex was administered in 2-L water via nasogastric intubation to five Standardbred horses for three consecutive days (total dose bicarbonate 0.42 ± 0.02 g/kg). Serial blood samples were taken over Days 1-5, with the final day (5) intended to simulate a 'clear day', and TCO2 was analysed. Following the first bicarbonate administration, plasma TCO2 peaked at 6 h (34.8 ± 1.3 mmol/L), returning to baseline by 23 h. On Day 2, four out of the five horses showed a peak greater than 36.0 mmol/L (mean 37.0 ± 2.1 mmol/L). With daily repeated dosing, plasma TCO2 peaked progressively earlier, and by Day 3, the peak occurred at 2 h and concentrations declined more rapidly. On Days 4 and 5, TCO2 levels remained low (<32.1 mmol/L on Day 4 and between 27.0-31.2 mmol/L on Day 5). These studies demonstrate that serial dosing of a 'split dose' of sodium bicarbonate on three consecutive days does not result in the accumulation or carry-over of plasma TCO2 levels beyond the levels observed following a single dose.

An immuno polymerase chain reaction screen for the detection of CJC-1295 and other growth-hormone-releasing hormone analogs in equine plasma.

CJC-1295 is a 30 amino acid peptide-based drug that stimulates the release of growth hormone (GH) from the pituitary gland. It is unique among performance-enhancing peptides due to the presence of a reactive maleimidopropionic acid group that covalently links the peptide to free thiols on the surface of plasma proteins. Once conjugated, CJC-1295 remains active in the bloodstream for significantly longer than non-conjugated peptide-based drugs that are rapidly excreted. Conjugation of CJC-1295 to plasma proteins prevents its detection by top-down mass-spectrometry-based peptide screening protocols as it effectively becomes a macromolecular protein with an undefined molecular weight. Using a pair of monoclonal antibodies raised against the CJC-1295 peptide, we present an immuno-polymerase chain reaction (I-PCR) assay that is capable of detecting the CJC-1295-protein conjugate at concentrations down to 0.8 pg/mL. Detection of endogenous equine GHRH necessitated a screening threshold for CJC-1295 in equine plasma of 50 pg/mL. The effectiveness of the assay for controlling the illicit use of CJC-1295 was confirmed in equine blood samples after administration in thoroughbred race horses.