Reliability, reference values and factors related to maximum bite force measured by the Innobyte system in healthy adults with natural dentitions.

OBJECTIVES: We aimed to determine the predictors of maximum bite force (MBF), as measured with the Innobyte system, and to assess the reliability and reference values for MBF in young adults with natural dentitions. METHODS: This cross-sectional test-retest study included 101 dental students with natural dentitions. Participants had their dental occlusion examined and completed three questionnaires: the Temporomandibular disorders Pain Screener, Oral Behavior Checklist, and Jaw Functional Limitation Scale. Body mass index and muscle mass percentage were determined, and handgrip strength was measured with a dynamometer. The MBF was measured with Innobyte, with reliability assessed by the intraclass correlation coefficient, expressing reference values as MBF percentiles. Bivariate tests and multiple linear regression models were used for statistical analysis. RESULTS: The intraclass correlation coefficient for the MBF was 0.90, with 10th to 90th percentiles of 487-876 N for females and 529-1003 N for males. A positive relationship existed between the MBF and male sex, muscle mass percentage, overbite, handgrip strength, and possible sleep/awake bruxism. Stepwise regression showed that overbite, handgrip strength, and possible sleep/awake bruxism had the greatest effect on the MBF, explaining 27% of the variation. CONCLUSIONS: This study provides reference values for MBF when using the Innobyte system and shows excellent reliability. Overbite, general strength, and self-reported bruxism appear to be important predictors of MBF. CLINICAL RELEVANCE: Innobyte is a reliable device that can be used to measure MBF bilaterally. Self-reported bruxism is associated with an 8%-10% increase in MBF.

Diagnostic accuracy of clinical signs to detect erosive tooth wear in its early phase.

BACKGROUND: Agreement exists about most of the clinical features of erosive tooth wear, though no evidence supports their validity in diagnosing the condition. OBJECTIVE: This study aimed to determine the accuracy of clinical signs for diagnosing erosive tooth wear in a young adult general population. METHODS: We conducted a cross-sectional study of dental students. In the first session, two examiners independently determined the presence of erosive tooth wear based on glazed enamel surfaces, morphological changes on non-occlusal surfaces, flattening of convex areas, or any type of concavity. In the second session, one examiner recorded the presence of clinical signs according to the Tooth Wear Evaluation System. The diagnostic accuracy of each clinical sign, both alone and combined, was assessed by calculating their sensitivity and specificity for detecting erosive tooth wear and performing multivariate logistic regression models. RESULTS: Of the 147 participants (78 women and 69 men; median age, 22 years) we included, 76.2% had erosive tooth wear. The single clinical signs with greatest balance between the sensitivity and specificity were 'convex areas flatten' (63% and 71%, respectively) and 'dull surface' (47% and 89%, respectively). Multivariate logistic regression revealed that 'preservation of the enamel cuff' (odds ratio, 22) and the combination of 'smooth silky shining, silky glazed appearance, and dull surface' (odds ratio, 68) had the best predictive values. CONCLUSIONS: The most accurate clinical signs for detecting early erosive tooth wear were dull surface, flattened convex areas and preservation of the enamel cuff.

Sex-specific reference values for the crown heights of permanent anterior teeth and canines for assessing tooth wear.

OBJECTIVE: We propose sex-specific reference values for the clinical crown height of anterior teeth and canines. MATERIAL AND METHODS: In this cross-sectional study, 1426 teeth were analysed from 169 undergraduate and postgraduate dental students (83 women and 86 men, median age 22 years). Teeth with worn or totally restored incisal edges, or gingival inflammation were excluded. Age, gender and body height were recorded and the degree of tooth wear was scored according to the quantification module of the Tooth Wear Evaluation System. The clinical crown heights of all anterior teeth and canines were measured from the gingival margin to the incisal edge with a digital calliper. Reference values for tooth groups were obtained at the percentiles 10, and expressed by sex if there was a significant difference between men and women. RESULTS: Mean crown heights were bigger in men than in women for each tooth group (p = .028). Clinical crown heights showed sexual dimorphism at the 10th percentiles for all tooth groups except for mandibular anterior teeth. CONCLUSIONS: For assessing tooth wear, the sex-specific reference values for the clinical crown height of young adults Caucasoids range from 7.5 mm to 9.0 mm in women and from 7.5 mm to 9.5 in men.

Attitudes and opinions towards the prevention of orofacial injuries among water polo coaches in Catalonia: A cross-sectional study.

BACKGROUND/AIM: Although orofacial injuries are frequent in water polo, fewer than 10% of players use mouthguards. The aim of this study was to determine the degree to which coaches and sports club managers encourage mouthguard use in water polo and to explore their opinions regarding other strategies designed to reduce the prevalence of orofacial injuries. MATERIAL AND METHODS: This was a cross-sectional study in which the coaches and sports club managers of 16 water polo clubs in Catalonia were invited to participate. An online questionnaire was administered to the coaches to obtain general data, to determine whether they had recommended mouthguard use to their players and to record their opinions on other strategies designed to reduce the prevalence of orofacial injuries. Sports club managers were interviewed about the facilities offered by their clubs for players to obtain mouthguards and about their attitudes regarding the prevention of orofacial injuries. RESULTS: The questionnaire was administered to 72 coaches who trained 111 teams during the 2019-2020 season, together with 14 sports club managers. Coaches of only 11 teams (10%) recommended mouthguard use to their players. Two clubs (14%) offered some facilities to their players to obtain mouthguards. Interestingly, only 18% of the coaches believed that mouthguard use should be mandatory, in contrast to 50% of the sports club managers (p = 0.017; Fisher's exact test). Most coaches and sports club managers believe that a video monitoring system should be used to identify dangerous play and that orofacial injuries should be reported under a surveillance programme. CONCLUSIONS: Few water polo coaches recommend mouthguard use to their players and very few clubs offer facilities to obtain custom-made oral protection. However, most coaches and sports club managers agree that the rules should be modified to protect players from aggressive play.

Effect of thickness and occlusal accommodation on the degree of satisfaction with mouthguard use among water polo players: A randomized crossover trial.

BACKGROUND/AIM: The optimal mouthguard type and design for each player and sport are currently unknown. The aim of this study was to assess the effect of using a thicker custom-made mouthguard with occlusal accommodation on the degree of satisfaction among water polo players. MATERIAL AND METHODS: Twenty-five elite water polo players participated in this randomized four-period crossover trial conducted from February to May 2019. For each participant, two customized mouthguards were fabricated using 4-mm ethyl vinyl acetate foil: Type A included no occlusal accommodation, and Type B included a 2-mm occlusal accommodation. Players wore each mouthguard during training sessions and competitions for 2 weeks in one of two randomized sequences. After each match or training session, players were asked to evaluate the mouthguards on 10-point scales across three domains: discomfort or interference with function, protection, and general satisfaction. Mouthguard preference was also recorded. RESULTS: The mouthguard with occlusal accommodation was reported to interfere more with speech and swallowing (P < .001) and with esthetics, breathing, and athletic performance (P < .05) compared with the conventional mouthguard. Although occlusal accommodation was associated with a higher perceived degree of protection (mean difference 0.5; 95% CI: 0.2-0.8), players were still more satisfied with the conventional mouthguard (mean difference 1.5; 95% CI: 0.8-2.3). Two players preferred the occlusal mouthguard, whereas 22 preferred the conventional mouthguard (P = .007). CONCLUSIONS: Among water polo players, occlusal accommodation increasing the thickness of the custom-made mouthguards may offer a greater perceived sense of protection, but this comes at the cost of greater discomfort and reduced overall satisfaction. Dentists can recommend conventional mouthguards for most water polo players.

Experience with mouthguards and prevalence of orofacial injuries among field hockey players in Catalonia.

BACKGROUND/AIM: Orofacial injuries are a serious problem in field hockey. The aim of this study was to determine the prevalence of orofacial injuries in field hockey players in Catalonia, the frequency of mouthguard use, the types of mouthguards used and the degree of interference with oral function. MATERIAL AND METHODS: In this cross-sectional study, 325 field hockey players (28% women) from all age categories completed a questionnaire about orofacial injuries occurring during their sporting lives, including dental injuries, oral lacerations and episodes of acute temporomandibular disorder (TMD) pain. The questionnaire also asked about the experience of using a mouthguard, the type of mouthguard used and any adverse effects of use. The degree of interference with oral function was compared by type of mouthguard (mouth-formed, custom-made and pre-fabricated mouthguards) using the Kruskal-Wallis test. RESULTS: Half of the players (50.2%) reported at least one orofacial injury during their sporting lives. The mean number of oral lacerations, TMD pain episodes and dental injuries were 1.59, 0.24 and 0.18, respectively. In total, 310 players (95.7%) had tried a mouthguard, and of these 269 (86.8%) and 283 (91.3%) still used a mouthguard habitually during training and competition, respectively. Only 11 players (3.5%) had tried all three types of mouthguards, and 71 players (22.9%) had tried two types of mouthguard. By type, 217 players (70.0%) had tried mouth-formed (boil-and-bite) mouthguards, 156 (50.3%) had tried custom-made mouthguards and 30 (9.7%) had tried pre-fabricated mouthguards. Custom-made mouthguards were rated as more comfortable than the mouth-formed type (P < .05). CONCLUSIONS: The prevalence of orofacial injuries among field hockey players is relatively high. Most players habitually use a mouthguard during training and competition, typically preferring custom-made or a mouth-formed types. Custom-made mouthguards were considered the most comfortable.

Tamoxifen induces apoptosis and inhibits respiratory burst in equine neutrophils independently of estrogen receptors.

Neutrophils play an important role in the exacerbation and maintenance of severe equine asthma; persistent neutrophil activity and delayed apoptosis can be harmful to surrounding tissues. Tamoxifen (TX) is a nonsteroidal estrogen receptor modulator with immunomodulatory effects and induces early apoptosis of blood and bronchoalveolar lavage neutrophils from horses with acute lung inflammation. This study investigated if the in vitro effects of tamoxifen are produced by its action on nuclear (α and ß) and membrane (GPR30) estrogen receptors in healthy equine neutrophils. Results showed that TX inhibits neutrophil respiratory burst induced by opsonized zymosan in a dose-dependent manner. Nuclear (17-ß-Estradiol) and GPR30 cell membrane (G1) estrogen receptor agonists and their antagonists (ICI 182,780 and G15, respectively) do not block or reproduce the effect of TX. Therefore, TX does not inhibit respiratory burst through estrogen receptors. TX (8.5 µM) also increased phosphatidylserine translocation, a marker of early apoptosis, which did not occur with any of the estrogen receptor agonists or antagonists. Thus, tamoxifen generates dose-dependent inhibition of respiratory burst and increased early apoptosis in healthy equine neutrophils, independently of nuclear or membrane estrogen receptors. Further studies are necessary to explore the signaling pathways of tamoxifen-induced ROS inhibition and phosphatidylserine translocation.

Satisfaction of patients with amyotrophic lateral sclerosis with an oral appliance for managing oral self-biting injuries and alterations in their masticatory system: A case-series study.

STATEMENT OF PROBLEM: About 10% of patients with amyotrophic lateral sclerosis (ALS) are candidates for oral treatment specifically because of traumatic injuries in the lips, cheeks, or tongue due to self-biting. However, patients with ALS have a prevalence of temporomandibular disorder (TMD) similar to that in the general population. PURPOSE: The purpose of this case-series study was to determine the degree of satisfaction of patients with ALS with an oral appliance for managing oral self-biting lesions or symptoms related to TMDs. This study also assessed the degree of improvement of the chief complaint and the compliance with and adverse effects of this treatment. MATERIAL AND METHODS: Eleven patients with ALS who sought oral treatment because of oral self-biting or TMD-related symptoms were included. A custom complete-coverage acrylic resin device was fabricated and fitted to each participant. A follow-up visit was planned for 3 months after the placement of the oral appliance, at which point the patients would rate the degree of improvement or worsening of the chief complaint and their degree of satisfaction with the treatment. A 1-sample t test was used to assess whether the degree of improvement of the chief complaint was significant. RESULTS: Participants reported a mean of 61% (95% confidence interval [CI] 38% to 84%) improvement of the chief complaint and a mean of 84% (95% CI 72% to 97%) satisfaction with the treatment. The mean rate of compliance was 62% (95% CI 40% to 84%) of the recommended time, and only a few adverse effects were reported. CONCLUSIONS: Participants with ALS were highly satisfied with the use of an oral appliance to manage oral self-biting or TMD-related symptoms. Adherence to this treatment was high, and no major adverse effects were observed.

Satisfaction with shortening the palatal extension of a mouthguard for water polo players: A randomized crossover study.

BACKGROUND/AIM: Approximately 50% of water polo players have suffered orofacial injuries. However, fewer than 8% of players wear a mouthguard. A more comfortable mouthguard design is therefore needed to increase compliance. The aim of this study was to assess the effect of reducing the palatal extension of a custom-made mouthguard on the degree of satisfaction with a mouthguard among water polo players. MATERIALS AND METHODS: Eighteen elite water polo players participated in this randomized crossover trial. Two custom-made mouthguards were fabricated for each participant using 4-mm-thick ethyl vinyl acetate foils, defined by the extension of the palatal margin from the cervical line: conventional (6 mm) and shortened (2 mm). The mouthguards were worn during all training sessions and matches, in a randomized sequence (one mouthguard type for the first and fourth weeks and the other for the second and third weeks). Mouthguards were evaluated on 10-point scales for discomfort, interference with oral functions, protection, and general satisfaction after each training session or match. RESULTS: Players evaluated the shortened mouthguard as having less interference with speech (Effect 1.30; P < 0.001), breathing (Effect 0.98; P = 0.004), swallowing (Effect 1.30; P < 0.001), and athletic performance (Effect 0.61; P = 0.03) compared with the conventional mouthguard. The perceived degree of protection was similar among participants when wearing each type of mouthguard. Overall, players were more satisfied with the shortened mouthguard (Effect 0.64; P = 0.03). CONCLUSIONS: Reducing the palatal extension of a custom-made mouthguard from 6 to 2 mm improves the overall satisfaction of elite water polo players without affecting the perceived degree of protection.

Risk of orofacial injuries and mouthguard use in water polo players.

BACKGROUND/AIM: The incidence of orofacial injuries and the use of mouthguards in water polo players have not been well established. The aim of this study was to determine the incidence of orofacial injuries in water polo players. Frequency of mouthguard use, the types of mouthguards used and the degree of interference with oral functions were also assessed. MATERIAL AND METHODS: In this cross-sectional study, 347 water polo players completed a questionnaire about the orofacial injuries suffered in the 2015-2016 season and the experience of using a mouthguard, such as the type of mouthguard used and the degree of interference with oral functions. RESULTS: In the 2015-2016 season, 57.9% of the players reported at least one orofacial injury, with mean numbers of 2.7 oral lacerations, 0.4 episodes of temporomandibular pain and 0.06 dental injuries. Among the 35 players (10.1%) who had tried a mouthguard, only four (1.2%) used it habitually. Some players had tried more than one type of mouthguard; 26 had tried the mouth-formed type; 11 the custom-made type; and 7 the prefabricated mouthguard. Custom-made mouthguards were rated as more comfortable than the mouth-formed type (P < 0.05). The main disadvantages of mouth-formed mouthguards were interferences with speaking, breathing and swallowing. CONCLUSIONS: The incidence of orofacial injuries in water polo players is high. Although some players had tried a mouthguard, mainly the mouth-formed type, most of them do not wear them routinely for training and competition.

Effects of low-dust forages on dust exposure, airway cytology, and plasma omega-3 concentrations in Thoroughbred racehorses: A randomized clinical trial.

BACKGROUND: Racehorses commonly develop evidence of mild asthma in response to dust exposure. Diets deficient in omega-3 polyunsaturated fatty acids (Ω-3) might exacerbate this response. HYPOTHESIS: To compare dust exposure, bronchoalveolar lavage fluid (BALF) cytology, and plasma Ω-3 and specialized pro-resolving mediators (SPM) concentrations amongst racehorses fed dry hay, steamed hay, and haylage. ANIMALS: Forty-three Thoroughbred racehorses. METHODS: Prospective clinical trial. Horses were randomly assigned to be fed dry hay, steamed hay, or haylage for 6 weeks. Measures of exposure to dust in the breathing zone were obtained twice. At baseline, week-3, and week-6, BALF cytology was examined. Plasma lipid profiles and plasma SPM concentrations were examined at baseline and week 6. Generalized linear mixed models examined the effect of forage upon dust exposure, BALF cytology, Ω-3, and SPM concentrations. RESULTS: Respirable dust was significantly higher for horses fed hay (least-square mean ± s.e.m. 0.081 ± 0.007 mg/m3 ) when compared with steamed hay (0.056 ± 0.005 mg/m3 , P = .01) or haylage (0.053 ± 0.005 mg/m3 , P < .01). At week 6, BALF neutrophil proportions in horses eating haylage (3.0% ± 0.6%) were significantly lower compared with baseline (5.1 ± 0.7, P = .04) and horses eating hay (6.3% ± 0.8%, P < .01). Plasma eicosapentaenoic acid to arachidonic acid ratios were higher in horses eating haylage for 6 weeks (0.51 ± 0.07) when compared with baseline (0.34 ± 0.05, P < .01) and horses eating steamed (0.24 ± 0.02, P < .01) or dry hay (0.25 ± 0.03, P < .01). CONCLUSIONS AND CLINICAL IMPORTANCE: Steamed hay and haylage reduce dust exposure compared with dry hay, but only haylage increased the ratio of anti-inflammatory to pro-inflammatory lipids while reducing BAL neutrophil proportions within 6 weeks.

Effect of Lavage Solution Type on Bronchoalveolar Lavage Fluid Cytology in Clinically Healthy Horses.

Equine bronchoalveolar lavage (BAL) is usually performed with 250-500 mL of isotonic saline at pH 5.5. The acidic pH of saline may cause an increase in airway neutrophil count 48 h after BAL. Other isotonic solutions such as Ringer's solution, phosphate-buffered saline (PBS) or Plasma-Lyte 148® have a neutral pH of 7.4 and might be a better choice for BAL by not provoking inflammation and the influx of neutrophils into airways. BAL was performed in four healthy horses in four different lung lobes using four different solutions in a randomized crossover design. In each lobe, BAL was performed twice with a 48 h interval using 250 mL of solution. Automated total nucleated cell counts (TNCs) were recorded, and differential cell counts in lavage fluid were determined by two investigators blinded to treatments. The mean volume of BAL fluid retrieved was 51 ± 14%. The mean neutrophil percentage (%N) increased from 1.5 ± 0.9% to 14.7 ± 9.6% at 48 h (p < 0.001) but was not significantly affected by the solution used or the lung lobe sampled. In conclusion, in this study, the influx of neutrophils into airways after BAL was independent of the type of isotonic solution used and the lung lobe sampled. Saline remains an appropriate solution for BAL in horses.

Satisfaction with labial reinforcement of custom-made mouthguards among a cohort of rugby union players: A randomized crossover trial.

PURPOSE: The optimal mouthguard design for athletes remains unclear. This study assessed satisfaction and preference among rugby union players for custom mouthguards with and without labial reinforcement. It also assessed discomfort and perceived protection. MATERIALS AND METHODS: This prospective randomized controlled trial used a crossover design of four 1-week periods to compare conventional (Type A) and labial reinforced (Type B) customized 2 mouthguards for rugby union players from February to May 2022. Type B mouthguards included a 0.75-mm insert of polyethylene terephthalate glycol (Duran) in the anterior labial region. We ensured intraoral occlusion accommodation for both mouthguards. Players wore each mouthguard type when training and in competitive matches for 2 weeks according to one of two randomized sequences, and after each session, they rated the mouthguard on 10-point scales regarding discomfort, functional interference, protection, and general satisfaction. After 4 weeks, we asked participants to nominate their preferred mouthguard. RESULTS: In total, 22 of the 24 invited players (16 men and 6 women) were included. We observed no significant differences in discomfort, functional interference, protection, or general satisfaction by mouthguard type (P > .05 Wilcoxon test). Ultimately, 12 players (55%) preferred the Type A mouthguard and 10 (45%) preferred the Type B mouthguard (P = .832; one-sample binomial test). No serious adverse events occurred. CONCLUSIONS: Labial reinforcement does not affect satisfaction, perceived comfort and protection, or mouthguard preference among rugby union players. Int J Prosthodont 2023. doi: 10.11607/ijp.8444 Trial registration: NCT05238480 (ClinicalTrials.gov).

Prevalence of dental attrition and its relationship with dental erosion and salivary function in young adults.

OBJECTIVES: The aim of this study was to estimate the prevalence of dental attrition in a young adult population and to explore associated factors. METHOD AND MATERIALS: Dental students aged 18 to 40 years old with a minimum of 24 natural teeth were invited to take part in this cross-sectional study. Their demographic information, medical history, perceived stress, frequency of dietary acid intake, and frequency of oral habits were obtained through several questionnaires. Assessment of each type of tooth wear (erosion, attrition, and abrasion) was performed according to the tooth wear evaluation system (TWES 1.0). All participants underwent salivary tests. Statistical analysis was performed by chi-squared or Mann-Whitney tests and logistic regression models. RESULTS: In total, 178 participants (88 women and 90 men) with a median age of 22 years were included and of those 74.7% (95% confidence interval [CI], 68% to 81%) had dental attrition. Univariate analysis revealed positive associations for male sex, age, body mass index, awake bruxism frequency, and erosive tooth wear with the presence of dental attrition. Multivariable logistic regression (Nagelkerke r2 = 0.31) indicated that dental attrition was associated with erosive tooth wear (adjusted odds ratio [aOR], 6.3; 95% CI, 2.8 to 14.2), body mass index (aOR, 1.3; 95% CI, 1.1-1.5), and age (aOR, 1.2; 95% CI 1.0 to 1.3). CONCLUSION: Dental attrition is present in most young adults of Catalonia. The associated factors were erosive tooth wear, body mass index, and age. Slight alterations of salivary parameters do not seem to predict dental attrition. (Quintessence Int 2023;54:168-175; doi: 10.3290/j.qi.b3622405).

Effect of different adjuvant formulations on the antibody response of horses to porcine zona pellucida proteins.

Immunization with porcine zona pellucida (PZP) proteins is being used successfully to induce infertility in wildlife including horses. However, widespread adoption of this method to control the growth of horse populations requires further refinement in order to induce long-term infertility, reduce the frequency and severity of injection site reactions, and make the vaccines easier to administer. The next generation of PZP-based vaccines will likely be a controlled-release formulation with different adjuvants from the Freund's adjuvants used in existing vaccines. We evaluated the response of equine peripheral blood mononuclear cells to a cationic nanoparticle adjuvant, Nano-11, alone and with the TLR agonists poly(I:C) and CpG ODN as a screen to develop an adjuvant system suitable for immunization of horses. The secretion of IL-1ß, TNF and CXCL10 were used as readouts. The combination of poly(I:C) with Nano-11 significantly increased the secretion of IL-1ß and TNF in comparison with Nano-11 only, with little effect of further addition of CpG ODN. The efficacy of the Nano-11/poly(I:C) adjuvant to enhance the immune response to native PZP proteins was determined in horses. Horses were immunized twice with the licensed Zonastat-H vaccine or PZP with Nano-11/poly(I:C) emulsified in silicone oil. A third group received PZP with the saponin adjuvant QA-21 emulsified in silicone oil. The horse sera collected monthly after the injections had increased anti-PZP IgG antibodies with the strongest response observed with Zonastat-H. We conclude that Nano-11/poly(I:C) is a potential candidate for the development of a controlled release formulation of a next generation PZP-based immunocontraception.

A seasonal idiopathic hepatitis syndrome in horses presented to a Midwestern veterinary teaching hospital.

OBJECTIVE: To report history, clinical examination findings, clinicopathologic findings, diagnostic test results, treatment, and outcome in horses with a novel idiopathic hepatitis syndrome. ANIMALS: 13 client-owned horses. PROCEDURES: Medical records of horses that were presented with fever and increased blood liver enzyme activity over a 16-month period were reviewed (December 1, 2020, to April 1, 2022). Collected data included signalment, history, clinical and clinicopathologic findings, diagnostic test results, treatment, clinical progression, and short-term outcome. RESULTS: Affected horses were presented between December and April of each of the 2 seasons investigated. The majority of horses developed cyclic fevers over the course of 3 weeks, during which time histologic evidence of hepatitis was observed. Histologic lesions included hepatic necrosis, neutrophilic to lymphohistiocytic inflammation, biliary epithelial injury, and portal fibrosis. Systemic inflammation was evidenced by increased serum amyloid A concentration and leukon changes. No horse developed signs of hepatic insufficiency, and all horses clinically recovered. Return of serum activity of GGT to within the reference range occurred within 16 weeks in most horses. Histologic lesions remained evident up to 27 weeks after initial presentation in 1 horse. CLINICAL RELEVANCE: Although an etiologic agent has not been identified, an apparently seasonal equine hepatitis syndrome was characterized by fever, systemic inflammation, increased liver enzyme activity, and histologic evidence of hepatitis. An infectious cause is suspected on the basis of histology and outcome.

A randomised, controlled trial to determine the effect of levothyroxine on Standardbred racehorses.

BACKGROUND: The use of thyroid supplement is pervasive in athletic horses although its effects on measures of performance are not known. OBJECTIVES: One purpose of this study was to determine whether supra-physiologic doses of levothyroxine affect the velocities at which blood lactate was greater than 4 mmol/L (VLa4 ) and heart rate was over 150 (V150 ) and 200 (V200 ) beats per minute respectively. Additionally, a survey of post-race blood samples was also conducted to determine whether high thyroxine concentrations were common in racehorses. STUDY DESIGN: A randomised, crossover, trial was performed in six healthy Standardbred racehorses. METHODS: Study 1: T4 was determined in 50 post-race samples from a single Standardbred meet. Study 2: Research horses were trained to fitness and then randomised to one of three treatments: carrier, 0.1 mg/kg thyroxine or 0.25 mg/kg thyroxine for 2 weeks. Horses completed a standardised exercise treadmill test (SET) to fatigue on the last day of treatment. Serum free and total thyroxine and triiodothyronine were determined on the day of SET testing. Blood lactate and ECG data were collected during the SET at 6, 8, 10, 11, and 12 m/s and during recovery. The effect of treatment and SET on heart rate and blood lactate was examined using generalised linear mixed models. Post hoc analysis was adjusted for multiple comparisons using Tukey's Test. Data were expressed as mean ± standard deviation and P < .05 was considered significant. RESULTS: Study 1: The median T4 value in this population of horses was 2.00 µg/dL (laboratory's normal range 1.5-4.5 µg/dL) and 3 of 50 racehorses had values above the laboratory reference range. Study 2: Levothyroxine at 0.25 mg/kg resulted in higher heart rates during SET (199 ± 30, 223 ± 17 and 239 ± 9 bpm at 6, 8 and 10 m/s respectively) and recovery (144 ± 20 and 119 ± 15 at 5 and 15 min) as compared to placebo (176 ± 18, 203 ± 10 and 219 ± 6 bpm at 6, 8, and10 m/s and 126 ± 5, 102 ± 11 at 5-15 minutes respectively). Three of six horses developed cardiac arrhythmias including atrial fibrillation. MAIN LIMITATIONS: A relatively small number of animals were used and a SET is not identical to actual racing conditions. CONCLUSIONS: Supra-physiologic thyroxine supplementation caused a decreased V200 during a standard exercise test and may result in cardiac arrhythmias.

Effects of forages, dust exposure and proresolving lipids on airway inflammation in horses.

OBJECTIVE: To investigate the role of omega-3 polyunsaturated fatty acids (Ω-3)-derived proresolving lipid mediators (PRLM) in the resolution of mild airway inflammation in horses. ANIMALS: 20 horses with mild airway inflammation. PROCEDURES: Horses previously eating hay were fed hay pellets (low Ω-3 content; n = 10) or haylage (high Ω-3 content; 9) for 6 weeks. Dust exposure was measured in the breathing zone with a real-time particulate monitor. Bronchoalveolar lavage (BAL) was performed at baseline, week 3, and week 6. The effect of PRLM on neutrophil apoptosis and efferocytosis was examined in vitro. BAL fluid inflammatory cell proportions, apoptosis of circulating neutrophils, efferocytosis displayed by alveolar macrophages, and plasma lipid concentrations were compared between groups fed low and high amounts of Ω-3 by use of repeated measures of generalized linear models. RESULTS: Dust exposure was significantly higher with hay feeding, compared to haylage and pellets, and equivalent between haylage and pellets. BAL fluid neutrophil proportions decreased significantly in horses fed haylage (baseline, 11.8 ± 2.4%; week 6, 2.5 ± 1.1%) but not pellets (baseline, 12.1 ± 2.3%; week 6, 8.5% ± 1.7%). At week 6, horses eating haylage had significantly lower BAL neutrophil proportions than those eating pellets, and a significantly lower concentration of stearic acid than at baseline. PRLM treatments did not affect neutrophil apoptosis or efferocytosis. CLINICAL RELEVANCE: Despite similar reduction in dust exposure, horses fed haylage displayed greater resolution of airway inflammation than those fed pellets. This improvement was not associated with increased plasma Ω-3 concentrations. Feeding haylage improves airway inflammation beyond that due to reduced dust exposure, though the mechanism remains unclear.