Respiratory health in horses encompasses the study of the equine respiratory system, its function, and the various conditions that can affect it. The respiratory system in horses includes the upper airways, lungs, and associated structures, which facilitate gas exchange and are vital for maintaining physiological homeostasis during rest and exercise. Common respiratory conditions in horses include equine asthma, infectious diseases like strangles, and exercise-induced pulmonary hemorrhage (EIPH). These conditions can impact a horse's performance and overall health. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, physiology, pathophysiology, and management of respiratory health in horses.
Hwang J, Golla V, Metwali N, Thorne PS.Adverse respiratory health effects in the agricultural industry have been linked to particulate endotoxin exposure. However, whether the endotoxin concentration is significantly correlated to the size of the particle remains an open question. To date, limited research has been conducted to assess particulate endotoxin exposures in the agricultural industry in general or the equine industry in particular. A task-based exposure assessment was conducted to characterize the endotoxin levels of inhalable and respirable particles on four Kentucky farms during the summer season. We conducted personal...
With outbreaks of equine influenza continuing to be reported in the UK, Richard Newton and Fleur Whitlock of the Animal Health Trust discusses practical steps that vets can promote and practise to reduce the risk of the virus spreading.
Owens TG, Barnes M, Gargano VM, Julien L, Mansilla WD, Devries TJ, Mcbride BW, Merkies K, Shoveller AK.Soaking hay and steaming hay are strategies that are used to reduce respirable dust particles for horses but may result in variable nutrient losses, including nonstructural carbohydrates (NSC) and minerals. Since these losses have not been quantified in Canadian hay yet, the first aim of this study was to identify nutrient losses from first-cut timothy-alfalfa hay grown in southern Ontario, Canada, after soaking for 30 min or steaming for 60 min. It is uncertain whether horses prefer hay when it is dry, soaked, or steamed. To address this, 13 Standardbred racehorses were offered 2 of these hay...
Bayly W, Lopez C, Sides R, Bergsma G, Bergsma J, Gold J, Sellon D.Public pressure exists in the United States to eliminate race-day furosemide administration despite its efficacy in decreasing the severity of equine exercise pulmonary hemorrhage (EIPH). No effective alternative prophylaxis strategies have been identified. Objective: To investigate alternative protocols to race-day furosemide that might mitigate EIPH. Methods: Seven fit Thoroughbreds with recent EIPH. Methods: Double-blinded placebo-controlled Latin square crossover using a treadmill followed by a blinded placebo-controlled crossover study at a racetrack. First, horses exercised supramaximall...
Rossi H, Raekallio M, Määttä M, Tapio H, Hanifeh M, Junnila J, Rajamäki MM, Mykkänen A.Pneumonia is one of the potential complications of general anaesthesia in horses. Anaesthesia is known to increase neutrophils in bronchoalveolar lavage fluid (BALF) of horses after lateral recumbency, but studies after dorsal recumbency are lacking. Our primary aim was to determine when lung inflammation reaches its maximum and how rapidly BALF cytology returns to baseline after anaesthesia in dorsal recumbency. A secondary aim was to investigate the possible effect of vatinoxan, a novel drug, on the BALF cytology results. Six healthy experimental horses were enrolled in this observational cr...
Mainguy-Seers S, Vargas A, Labrecque O, Bédard C, Hélie P, Lavoie JP.Neutrophilic inflammation is believed to contribute to the airway obstruction and remodelling in equine asthma. Azithromycin, an antibiotic with immunomodulatory properties, reduces pulmonary neutrophilia and hyper-responsiveness in human asthmatics and decreases airway remodelling in rodent models of asthma. It was therefore hypothesised that azithromycin would improve lung function, mucus accumulation and central airway remodelling by decreasing luminal neutrophilia in severe equine asthma. The effects of a 10-day treatment with either azithromycin or ceftiofur, an antimicrobial without immu...
Tapio HA, Raekallio MR, Mykkänen AK, Al-Ramahi D, Scheinin M, Hautajärvi HJ, Männikkö S, Vainio O.A constant rate infusion (CRI) of medetomidine is used to balance equine inhalation anesthesia, but its cardiovascular side effects are a concern. This experimental crossover study aimed to evaluate the effects of vatinoxan (a peripheral α2-adrenoceptor antagonist) on cardiorespiratory and gastrointestinal function in anesthetized healthy horses. Six horses received medetomidine hydrochloride 7μg/kg IV alone (MED) or with vatinoxan hydrochloride 140μg/kg IV (MED+V). Anesthesia was induced with midazolam and ketamine and maintained with isoflurane and medetomidine CRI for 60min. Heart rate, ...
Bardell D, Mosing M, Cripps PJ.Arterial hypoxaemia is common in anaesthetised horses, but little information exists regarding restoration of arterial oxygen tension (PaO ) during recovery from anaesthesia, or if intra-operative management factors exert any longer-term effect. Objective: To evaluate PaO in horses recovering from general anaesthesia up to 1 h after resuming standing. Methods: Prospective observational clinical cohort study. Methods: Systemically healthy adult horses undergoing inhalational general anaesthesia for elective surgical procedures were studied. Arterial blood samples were obtained anaerobically pr...
Uchida-Fujii E, Niwa H, Kinoshita Y, Nukada T.Actinobacillus species are known to be pathogenic to horses. To clarify etiological agents of actinobacillosis in Japanese adult horses, 27 isolates from Japanese Thoroughbred racehorses putatively identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry as Actinobacillus were further identified by PCR of the A. equuli toxin gene, by CAMP test, and by 16S rRNA sequencing analysis. Actinobacillus equuli subsp. haemolyticus was isolated most frequently (16/27) and was related to respiratory infections. Actinobacillus equuli subsp. equuli (4/27) was isolated from...
Canola PA, Valadão CAA, Canola JC, Flôres FN, Lopes MCS.The objective of this study was to evaluate clinical and cardiovascular parameters and pleural and intra-abdominal pressures of horses after experimentally induced unilateral open pneumothorax. Prospective, experimental study-animals: seven healthy adult horses, 4 females and 3 males. Left hemithorax thoracotomy was carried out to create an open pneumothorax for 60 minutes. Pleural pressure (P) was directly obtained at the midpoint of the left eighth intercostal space before thoracotomy. Esophageal pressure (P), arterial blood gas analysis, left ventricular function, and ultrasonographic asses...
Airway obstruction is the main trait of severe equine asthma that affects respiratory function and elicits detrimental effects on clinical presentation. Only few and underpowered clinical studies have investigated the impact of improvement in lung function induced by bronchodilators on the clinical signs of asthma-affected horses. Objective: To identify the minimal important difference (MID) in lung function elicited by bronchodilator leading to a meaningful improvement in clinical signs. Methods: Pairwise meta-analysis and meta-regression analysis. Methods: Literature searches were performed ...
Varner KM, Hopster K, Driessen B.To assess effects of nitrogen and helium on efficacy of an alveolar recruitment maneuver (ARM) for improving pulmonary mechanics and oxygen exchange in anesthetized horses. Methods: 6 healthy adult horses. Methods: Horses were anesthetized twice in a randomized crossover study. Isoflurane-anesthetized horses in dorsal recumbency were ventilated with 30% oxygen and 70% nitrogen (treatment N) or heliox (30% oxygen and 70% helium; treatment H) as carrier gas. After 60 minutes, an ARM was performed. Optimal positive end-expiratory pressure was identified and maintained for 120 minutes. Throughout ...
To evaluate the effects of positive end-expiratory pressure (PEEP) alone and PEEP preceded by lung recruitment manoeuvre (LRM) on lung volumes and respiratory system mechanics in healthy horses undergoing general anaesthesia. Methods: Controlled, prospective clinical study. Methods: A group of 15 horses undergoing arthroscopy. Methods: Following anaesthetic induction, initial ventilatory settings were: tidal volume 15 mL kg, inspiratory:expiratory ratio 1:2, respiratory rate to maintain end-tidal CO between 5.3-6.6 kPa (40-50 mmHg). The following settings were implemented sequentially: zero PE...
Thorsteinsdóttir L, Jónsdóttir S, Stefánsdóttir SB, Andrésdóttir V, Wagner B, Marti E, Torsteinsdóttir S, Svansson V.Two types of gammaherpesviruses (γEHV) are known to infect horses, EHV-2 and EHV-5. Foals become infected early in life, probably via the upper respiratory tract, despite maternal antibodies. In this study, we analyzed samples from a herd of mares and their foals. The foals were followed from birth to 22 months of age and the dams during the first 6 months postpartum. Blood and nasal swab samples were taken regularly for evaluation of antibody responses, virus isolation and viral load by qPCR. EHV-2 was isolated on day 5, and EHV-5 on day 12, earlier than previously reported. γEHV specific a...
Ochi A, Sekiguchi M, Tsujimura K, Kinoshita T, Ueno T, Katayama Y.Equine multinodular pulmonary fibrosis (EMPF) is a recently described form of interstitial pneumonia associated with equine herpesvirus type 5 (EHV-5). This disease has been reported in North and South America, Europe and Oceania but not, to our knowledge, in horses in Japan. We diagnosed EMPF in two Thoroughbred horses in Japan on the basis of gross and histopathological findings. In both cases, significant gross lesions, restricted to the lungs, consisted of numerous firm and coalescing nodules widely distributed throughout the lung. The nodules were <3 cm in diameter and pale white to t...
Claußen G, Grau D, Hessel EF.It has been known for some years now that the occurrence of lameness in horses is closely related to the characteristics of the riding surface and that respiratory tract diseases can be induced by airborne particles. To ensure both optimal rideability (e.g., grip, elasticity, etc.) and low dust production, riding surfaces have to be regularly attended to, which also includes watering the floor. However, at present, it is not known what the individual moisture content of the various types of riding surface should be to ensure optimal rideability or what their potential for releasing dust is at ...
Dall Agnol AM, Beuttemmuller EA, Pilz D, Leme RA, Saporiti V, Headley SA, Alfieri AF, Alfieri AA.Equid gammaherpesvirus 2 (EHV-2) and 5 (EHV-5) are members of the Herpesviridae family and have been reported in horse populations worldwide. This study aimed to evaluate the presence of herpesvirus DNA in the upper respiratory tract of horses. Twenty-six nasal swabs were collected from asymptomatic adult horses of two different horse farms (A, n = 18; B, n = 8), both located in Southern Brazil. The EHV-1, EHV-2, EHV-4, and EHV-5 DNA analyses were performed using nested PCR assays targeting the glycoprotein B gene. Four (15.3%) and 12 (46.1%) of the 26 nasal swab samples were positive ...
Shaw DJ, Rosanowski SM.Epiglottic entrapment is a condition in racing horses, associated with abnormal respiratory noises and exercise intolerance. Epiglottic entrapment has been linked to both poor and superior athletic performance, leading to concerns regarding whether surgery is indicated, and whether surgical correction may have a deleterious effect on future race performance. The objective of the current study was to assess the race-day performance of horses racing with epiglottic entrapment and the effect of surgical correction on performance outcomes using an intra-oral technique in anaesthetised horses. A ca...
Wiklund M, Kellgren M, Wulcan S, Grubb T, Nyman G.Administration of pulsed inhaled nitric oxide (PiNO) improves arterial oxygenation in spontaneously breathing anaesthetised healthy horses and in horses undergoing colic surgery. However, because hypoventilation commonly occurs, horses are often mechanically ventilated to prevent hypercarbia. Objective: To evaluate the effects of PiNO on arterial oxygenation during anaesthesia in mechanically ventilated healthy horses and horses undergoing colic surgery. Methods: Prospective nonblinded clinical trial. Methods: Fifty horses undergoing elective arthroscopy (Group A) and 30 horses undergoing coli...
Klier J, Bartl C, Geuder S, Geh KJ, Reese S, Goehring LS, Winter G, Gehlen H.Equine asthma represents a naturally occurring animal model for human allergic neutrophilic asthma. Inhalative nanoparticle-bound cytosine-phosphate-guanosine (CpG-GNP) immunotherapy, independent of specific allergens, has already shown promising clinical and immunological results in previous studies and offers the possibility to treat the underlying cause of the disease. This study analyses the relationship between dose and response, and evaluates a possible long-term effect. In the prospective, randomised, double-blind clinical field study, 29 horses suffering from equine asthma received 10 ...
Morrison ML, Groover E, Schumacher J, Newton J, Pereira MM.Squamous cell carcinoma (SCC) is one of the most common malignant neoplasms in horses, but lingual SCC has seldom been reported. On separate occasions, a 12-year-old American Quarter Horse mare and an 18-year-old American Saddlebred stallion were presented to the Auburn University Large Animal Teaching Hospital for evaluation of weight loss, dysphagia, and ptyalism. Evaluation of each horse included physical examination, skull radiographs, oral examination, complete blood count and serum biochemistry profile, endoscopic evaluation of the mouth, and biopsy of tissue from a lesion found on the t...
Varegg MS, Kløverød KM, Austnes MK, Siwinska N, Słowikowska M, Zak A, Madej JA, Kandefer-Gola M, Ciaputa R, Nowak M, Niedzwiedz A.Pulmonary hemorrhage is a rare cause of death in horses. Hemorrhage within the respiratory tract has many causes, including mycosis of the guttural pouch, invasive procedures causing serious trauma to nasal conchae, or lung biopsy. We report on a rare case of a fatal pulmonary hemorrhage in a horse after a severe cough during bronchoalveolar lavage. To the best of our knowledge, this is the first report of spontaneous hemorrhage in a horse during bronchoalveolar lavage. Methods: A 21-year-old mare which belonged to the didactic herd of The Faculty of Veterinary Medicine underwent BAL procedure...
Vail KJ, Stranahan LW, Richardson LM, Yanchik AE, Arnold CE, Porter BF, Wiener DJ.Mycobacterial infections in horses are uncommon, but are caused most frequently by Mycobacterium bovis of the Mycobacterium tuberculosis complex or Mycobacterium avium of the M. avium complex. Disease caused by Mycobacterium intracellulare, the second most common species within the M. avium complex, has not been reported in horses to date. Mycobacteriosis in horses most often presents as enteric, pulmonary or, rarely, systemic disease. Here we report a case of M. intracellulare infection in a horse presenting as a granulomatous nasal mass.
Niedzwiedz A, Slawuta P, Zak A, Slowikowska M, Siwinska N, Rykała M, Nicpon J.Equine asthma syndrome is an allergic, inflammatory airway disease that usually affects older horses. Respiratory acidosis is an acid-base imbalance caused by alveolar hypoventilation. The acid-base balance may be assessed using the Henderson-Hasselbalch equation as well as the Stewart model. The authors hypothesized that systemic respiratory acidosis changes the ionic concentrations affecting water dissociation. The study group included 16 Warmblood, mixed breed horses of both sexes with a history of severe equine asthma, and 10 healthy horses were used as controls. Arterial and venous blood ...
Crispe EJ, Lester GD.Exercise-induced pulmonary hemorrhage (EIPH) occurs commonly in horses undergoing strenuous exercise. Reported risk factors include racing in cold temperatures and wearing of bar shoes. In horses with documented moderate to severe EIPH, increasing the interval between races and adopting a negative race pace strategy may reduce the severity of EIPH in subsequent races. EIPH seems to have an impact on performance only when moderate to severe. This occurs in a small number of starters, approximately 6%. EIPH often is erratic in severity from race to race, although across a population it is weakly...
Van Cleemput J, Poelaert KCK, Laval K, Van den Broeck W, Nauwynck HJ.The horse's respiratory tract daily encounters a plethora of respirable hazards including air pollutants, mycotoxins and airborne pathogens. To date, the precise effect of air pollution and mycotoxins on respiratory epithelial integrity and subsequent pathogen invasion in the horse has not been studied. Here, diesel exhaust particles (DEP) and three major mycotoxins (deoxynivalenol [DON], aflatoxin B1 [AFB1] and fumonisin B1 [FB1]) were applied to the apical surfaces of both ex vivo respiratory mucosal explants and in vitro primary equine respiratory epithelial cells (EREC) cultivated at the a...
Curtiss AL, Parente EJ.To report an epiglottopexy technique for the treatment of epiglottic retroversion (ER) in 2 horses. Methods: Case report. Methods: A 2-year-old thoroughbred gelding and a 6-year-old standardbred gelding, both with ER. Methods: Epiglottic retroversion was diagnosed via exercising endoscopic examination in both horses. Epiglottopexy technique was performed in both cases. Results: Both horses returned to previous racing class within 1 year after surgery. Repeat exercising endoscopy of 1 horse 6 months postoperatively revealed resolution of the ER. Conclusions: Epiglottopexy should be consider...
Bonomo CCM, Michelotto PV, Viccino C, Barussi FCM, Fernandes WR.Pulmonary haemorrhage occurs in sport horses performing high-intensity exercise, but the factors involved in the occurrence of pulmonary haemorrhage in jumping horses have not been elucidated. This study aimed to determine the occurrence of pulmonary haemorrhage and factors involved in competitive jumping horses. Fifty adult jumping horses competing in the city of São Paulo, Brazil, were included. The horses were divided into two groups based on jump height at competition: Low group (LG, n=26), with jump height between 1.00 and 1.20m, and High group (HG, n=24), with jump height between 1.30 a...
Raidal SL, McKean R, Ellul PA, Nielsen SG, Quinn CT.To characterize the effects of continuous positive airway pressure (CPAP) delivered by a commercial human CPAP device on respiratory function in foals with pharmacologically induced respiratory suppression. Methods: Prospective randomized, cross-over study comparing CPAP with spontaneous respiration and oxygen insufflation. Methods: University veterinary teaching hospital. Methods: Twelve foals born in consecutive seasons from a university teaching herd. Methods: Foals were randomized to receive 10 minutes of respiratory support by mask oxygen supplementation or CPAP as a first treatment after...
Jones JH.Taylor and Weibel's principle of symmorphosis hypothesized optimal design of the mammalian respiratory system, with no excess structure relative to its maximal O2 flux, VO2max. Although they found symmorphosis not to be a general principle of design, it might apply to a highly adapted aerobic athlete, e.g. the Thoroughbred racehorse. Using a mathematical model based on empirical data of the equine O2 transport system at normoxic VO2max, the fraction of the total limitation to O2 flux contributed by each of the respiratory transport steps is calculated as either the fractional change (F) in VO2...
The Journal of physiologyApril 15, 1996
Volume 492 ( Pt 2), Issue Pt 2 587-596 doi: 10.1113/jphysiol.1996.sp021331
Lafortuna CL, Reinach E, Saibene F.1. To investigate the effect of locomotor activity on the pattern of breathing in quadrupeds, ventilatory response was studied in four healthy horses during horizontal and inclined (7%) treadmill exercise at different velocities (1.4-6.9 m s(-1)) and during chemical stimulation with a rebreathing method. Stride frequency (f(s)) and locomotor-respiratory coupling (LRC) were also simultaneously determined by means of video recordings synchronized with respiratory events. 2. Tidal volume (V(T)) was positively correlated with pulmonary ventilation (V(E)) but significantly different linear regressi...
Robinson NE, Berney C, Behan A, Derksen FJ.Efficacy of inhaled fluticasone propionate (FP) for management of recurrent airway obstruction (RAO) has only been evaluated after several weeks' treatment. Objective: To compare efficacy of (1) 3-day treatments with FP to dexamethasone (DEX) for management of RAO; and (2) FP and DEX to no treatment in prevention of acute RAO exacerbations. Methods: Nine RAO affected horses. Methods: Crossover studies in RAO-affected horses compared (a) 3-day treatment of RAO exacerbation with FP (3 and 6 mg q12h) and DEX (0.1 mg/kg q24h) and (b) FP (6 mg q12h) and DEX (0.1 mg/kg q24h) to no treatment for prev...
McGorum BC, Dixon PM, Halliwell RE, Irving P.A comparison was made of the cellular and molecular components of bronchoalveolar lavage fluid (BALF) harvested from the left and right diaphragmatic lobes, the accessory lobe of the right lung and the apical lobe of the left lung, of seven control horses and six horses with symptomatic chronic obstructive pulmonary disease (COPD). Neither control nor symptomatic COPD affected horses showed significant regional differences in BALF recovery volumes, total and differential BALF cell counts, albumen adjusted total and absolute BALF cell counts, total and absolute pulmonary epithelial lining fluid...
Derksen FJ, Robinson NE.Pleural and esophageal pressures were compared in 6 standing sedated ponies. Pleural pressure was measured with blunt needles attached to transducers and inserted in the 10th intercostal space level with and 10 and 20 cm above the point of the shoulder. Two balloons (a condom and an esophageal balloon) attached to transducers measured esophageal pressure in the cranial, middle, and caudal portions of the thoracic part of the esophagus. Tidal volume was measured by integrating a flow signal derived from a pneumotachograph attached to an endotracheal tube inserted through a tracheostomy. Frequen...
Couëtil LL, Rosenthal FS, Simpson CM.The purpose of this study was to assess whether our method of inducing forced expiration detects small airway obstruction in horses. Parameters derived from forced expiratory flow-volume (FEFV) curves were compared with lung mechanics data obtained during spontaneous breathing in nine healthy horses, in three after histamine challenge, and in two with chronic obstructive pulmonary disease (COPD) pre- and posttherapy with prednisone. Parameters measured in the healthy horses included forced vital capacity (FVC = 41.6 +/- 5.8 liters; means +/- SD) and forced expiratory flow (FEF) at various perc...
Purohit RC, Mysinger PW, Redding RW.A continuous series of electroencephalograms (EEG) was obtained from each of 6 mature horses which had been given xylazine and ketamine hydrochloride IV. Electrocardiograms and respiratory rates were also obtained. The EEG of the unsedated standing adult horse displayed a dominant fast activity in the range of 25-35 Hz, 5-30 microV superimposed over slower 1-4 Hz, 10-50 microV activity with occasional 10-14 Hz, 10-40 microV spindle-type activity. The xylazine-sedated horse displayed hypersynchronous EEG patterns, with the dominant activity being 1-3 Hz, 10-70 microV with overlying mixed freque...
Strand E, Fjordbakk CT, Holcombe SJ, Risberg A, Chalmers HJ.Dynamic laryngeal collapse (DLC) associated with poll flexion is a newly diagnosed upper respiratory tract obstructive disorder that causes poor racing performance. Objective: To determine if Norwegian Coldblooded Trotters (NCTs) affected with DLC associated with poll flexion differ from normal, elite NCTs based on simple airway mechanics measurements. Methods: Five normal elite NCTs and 6 NCTs diagnosed previously with DLC underwent treadmill videoendoscopy while tracheal pressures were measured continuously. Alternating head positions were used such that horses were exercised with free head ...
Manohar M.Eight healthy adult grade ponies were studied at rest as well as during maximal exertion carried out with and without adenosine infusion (3 microM X kg-1 X min-1 into the pulmonary artery) on a treadmill to compare levels of blood flow in respiratory muscles with those in other vigorously working muscles and to ascertain whether there remained any unutilized vasodilator reserve in respiratory muscles of maximally exercising ponies. Radionuclide-labeled 15-micron-diam microspheres, injected into the left ventricle, were used to study tissue blood flows. During maximal exertion, there were incre...
Sweeney CR, Maxson AD, Soma LR.The frequency of upper respiratory tract abnormalities was determined in a selected population of racing Thoroughbreds. The prevalence of pharyngeal lymphoid hyperplasia was 34.2%; left laryngeal hemiplegia was 1.8%; and epiglottic entrapment was 0.74%. Excluding pharyngeal lymphoid hyperplasia and tracheal exudate, 3.7% of the population examined had upper respiratory tract abnormalities.
Ducharme NG, Hackett RP, Woodie JB, Dykes N, Erb HN, Mitchell LM, Soderholm LV.Contributes to the understanding of the pathogenesis of dorsal displacement of the soft palate during exercise so that management of this condition could be enhanced. Objective: That the thyrohyoid muscles play an important role in the stability of the laryngo-palatal relationship and that dysfunction of these muscles leads to dorsal displacement of the soft palate (DDSP) during exercise. Methods: Ten horses were exercised on a high-speed treadmill under 4 different treatment conditions: control conditions (n = 10), after resection of thyrohyoid muscles (TH, n = 10), after sham-treatment (n = ...
Sacks M, Byrne DP, Herteman N, Secombe C, Adler A, Hosgood G, Raisis AL, Mosing M.Left-sided cardiac volume overload (LCVO) can cause fluid accumulation in lung tissue changing the distribution of ventilation, which can be evaluated by electrical impedance tomography (EIT). Objective: To describe and compare EIT variables in horses with naturally occurring compensated and decompensated LCVO and compare them to a healthy cohort. Methods: Fourteen adult horses, including university teaching horses and clinical cases (healthy: 8; LCVO: 4 compensated, 2 decompensated). Methods: In this prospective cohort study, EIT was used in standing, unsedated horses and analyzed for convent...
Fuchs S, Klier J, May A, Winter G, Coester C, Gehlen H.Delivering active ingredients using biocompatible and biodegradable carriers such as gelatin nanoparticles (GNPs) to the lung constitutes a promising non-invasive route of administration. However, the pulmonary delivery of nanoparticle-based immunotherapy is still a field that requires more clarification. In this study, GNPs loaded with cytosine-phosphate-guanine oligodeoxynucleotides (CpG-ODN)-loaded and plain GNPs were aerosolised either by a conventional pressured metered dose inhaler (pMDI) or by active or passive vibrating-mesh (VM) nebulisers. GNP sizes after nebulisation by active and p...
Longworth KE.Pulmonary intravascular macrophages are an important part of the mononuclear phagocyte system in some species of mammals, mainly sheep and other ruminants, pigs, and horses. These cells phagocytize foreign particles, cell debris and pathogens that pass through the pulmonary circulation. Species with intravascular macrophages localize intravenously injected tracer particles and bacteria predominantly in the lung rather than the liver, and exhibit pulmonary hypertension when these cells are activated. Both in vivo and in vitro studies show that pulmonary intravascular macrophages have distinct s...
van Erck E, Votion DM, Kirschvink N, Art T, Lekeux P.To compare sensitivity of the impulse oscillometry system (IOS) with that of the conventional reference technique (CRT; ie, esophageal balloon method) for pulmonary function testing in horses. Methods: 10 horses (4 healthy; 6 with recurrent airway obstruction [heaves] in remission). Methods: Healthy horses (group-A horses) and heaves-affected horses (group-B horses) were housed in a controlled environment. At each step of a methacholine bronchoprovocation test, threshold concentration (TC(2SD); results in a 2-fold increase in SD of a value) and sensitivity index (SI) were determined for respir...
Ambrósio AM, Ida KK, Souto MT, Oshiro AH, Fantoni DT.To assess if positive end-expiratory pressure (PEEP) titration improves gas exchange and respiratory mechanics, without hemodynamic impairment in horses during anesthesia. Methods: Prospective, randomized study. Methods: Thirteen isoflurane-anesthetized healthy horses. Methods: After 60 minutes of anesthesia with spontaneous breathing, mechanical ventilation was initiated with an inspiratory-expiratory ratio of 1:2, PEEP of 5 cmH2O, tidal volume of 10-20 mL kg(-1) and respiratory rate adjusted to maintain normocapnia. Constant PEEP of 5 cmH2O was continued (control group; n = 6) or titrated (P...
Cha ML, Costa LR.This article discusses the benefits and limitations of inhalation therapy in horses. Inhalation drug therapy delivers the drug directly to the airways, thereby achieving maximal drug concentrations at the target site. Inhalation therapy has the additional advantage of decreasing systemic side effects. Inhalation therapy in horses is delivered by the use of nebulizers or pressured metered dose inhalers. It also requires the use of a muzzle or nasal mask in horses. Drugs most commonly delivered through inhalation drug therapy in horses include bronchodilators, antiinflammatories, and antimicrobi...
Pollock PJ, Reardon RJ, Parkin TD, Johnston MS, Tate J, Love S.There are potential advantages to imaging the upper portion of the respiratory tract (URT) of horses during ridden exercise. With the advent of a wireless endoscope, this is now possible. However, there has been no detailed validation of the technique and findings have not been compared to ridden speed. Objective: To assess the combined use of a Dynamic Respiratory Scope (DRS) and global positioning system (GPS) receiver for examining the URT of a group of Thoroughbred racehorses randomly selected from a single flat racehorse training establishment. Methods: Horses were selected randomly from ...
Oswald S, Peters J, Venner M, Siegmund W.Clarithromycin (CLA) is a well established macrolide antibiotic which is frequently used in therapy of airway diseases in foals. It is extensively metabolized by CYP3A4 resulting in the antimicrobial active metabolite 14-hydroxyclarithromycin (OH-CLA). Rifampicin (RIF) is often comedicated to prevent resistance and augment therapy. RIF is a known inducer for metabolizing enzymes and transporter proteins. Therefore, comedication might bare the risks of pharmacokinetic drug interactions which were investigated in a clinical trial. As no adequate method to determine CLA, RIF and their main metabo...
Overbeck W, Jäger K, Schoon HA, Witte TS.Endometritis constitutes a major problem in managing broodmares. The histological occurrence of polymorphonuclear neutrophils (PMNs) in the stratum compactum of the endometrium is accepted as the reference standard to diagnose endometritis in mares. The objective of this study was to determine the distribution of PMNs within different sampling locations of the uterus by cytological examinations and to compare it with PMN numbers in endometrial biopsies of the corresponding location. Cytological and endometrial samples were obtained from 37 uteri within 2 ± 1 hours after slaughter through smal...
Bolwell C, Rogers C, Gee E, McIlwraith W.The objective of the study was to determine the incidence of veterinary events that resulted in a horse failing to finish a race and identify risk factors for musculoskeletal injury (MSI) during a race. Data were obtained on Thoroughbred flat race starts in New Zealand between 1 August 2005 and 31 July 2011 (six racing seasons). Stipendiary Steward's reports were key-word searched to identify veterinary events that prevented a horse from finishing a race. Race data were used calculate the incidence of veterinary events per 1000 horse starts and Poisson regression was used to investigate risk f...
Mosing M, Waldmann AD, MacFarlane P, Iff S, Auer U, Bohm SH, Bettschart-Wolfensberger R, Bardell D.This study evaluated the breathing pattern and distribution of ventilation in horses prior to and following recovery from general anaesthesia using electrical impedance tomography (EIT). Six horses were anaesthetised for 6 hours in dorsal recumbency. Arterial blood gas and EIT measurements were performed 24 hours before (baseline) and 1, 2, 3, 4, 5 and 6 hours after horses stood following anaesthesia. At each time point 4 representative spontaneous breaths were analysed. The percentage of the total breath length during which impedance remained greater than 50% of the maximum inspiratory impeda...
Manohar M.The present study was carried out 1) to compare blood flow in the costal and crural regions of the equine diaphragm during quiet breathing at rest and during graded exercise and 2) to determine the fraction of cardiac output needed to perfuse the diaphragm during near-maximal exercise. By the use of radionuclide-labeled 15-micron-diam microspheres injected into the left atrium, diaphragmatic and intercostal muscle blood flow was studied in 10 healthy ponies at rest and during three levels of exercise (moderate: 12 mph, heavy: 15 mph, and near-maximal: 19-20 mph) performed on a treadmill. At re...
Relave F, David F, Leclère M, Alexander K, Hélie P, Meulyzer M, Lavoie JP, Marcoux M.To validate the use of the LigaSure™ Vessel Sealing System (LVSS) to perform thoracoscopic lung tissue biopsies in heaves-affected horses. Methods: Prospective clinical study. Methods: Heaves-affected horses (n=12). Methods: Lung biopsies (n=34) were collected with the LVSS (2-4 biopsies/horse) in horses with and without clinical signs of heaves. Thoracoscope (13th intercostal space [ICS]) and 2 instruments (between the 12-15th ICS) portals were used. Selected clinical and arterial blood gas variables were monitored. Postoperative pneumothorax was evaluated. Depth of thermal injury to the su...
Constantinopol M, Jones JH, Weibel ER, Taylor CR, Lindholm A, Karas RH.Because the maximal rate of O2 consumption (VO2max) of the horse is 2.6 times larger than that of steers of equal size, we wondered whether their pulmonary gas exchanger is proportionately larger. Three Standardbred racehorses [body mass (Mb) = 447 kg] and three domestic steers (Mb = 474 kg) whose cardiovascular function at VO2max had been thoroughly studied (Jones et al. J. Appl. Physiol. 67: 862-870, 1989) were used to study their lungs by morphometry. The basic morphometric parameters were similar in both species. The nearly 2 times larger lung volumes of the horses caused the gas exchange ...
Wagner PD, Erickson BK, Seaman J, Kubo K, Hiraga A, Kai M, Yamaya Y.Although the horse is considered an elite athlete with a specific VO2max some 2-4 times higher than man, maximal O2 transport is compromised both by moderately severe arterial desaturation and by failure to extract all O2 from blood perfusing exercising muscle. This prompted the present study to ascertain whether correction of arterial desaturation would proportionally augment VO2max and, if so, would O2 extraction behave in a manner predicted by diffusional transport limitation. Six two year old thoroughbreds were exercised to VO2max on a treadmill each on three separate occasions breathing g...
Goodrich LR, Nixon AJ, Fubini SL, Ducharme NG, Fortier LA, Warnick LD, Ludders JW.To determine whether preoperative epidural administration of morphine and detomidine would decrease postoperative lameness after bilateral stifle arthroscopy in horses. Methods: Prospective clinical controlled study. Methods: Eight adult horses that had bilateral arthroscopic procedures, including drilling of cartilage and subchondral bone within the femoropatellar joints. Methods: Horses were randomly separated into 2 groups. Preoperatively, 4 horses were administered a combination of epidural morphine (0.2 mg/kg) and detomidine (30 microg/kg), and 4 horses were administered an equivalent vol...
