Lung health in horses encompasses the study of respiratory system function, disease, and maintenance in equine species. The equine respiratory system is vital for oxygen exchange and plays a significant role in overall health and athletic performance. Conditions affecting lung health include inflammatory airway disease (IAD), recurrent airway obstruction (RAO), and exercise-induced pulmonary hemorrhage (EIPH). These conditions can impact a horse's respiratory efficiency and performance capabilities. Research in this area often focuses on understanding the pathophysiology, diagnosis, and management of respiratory diseases, as well as the impact of environmental factors on lung function. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, diagnostic approaches, and therapeutic strategies related to lung health in horses.
Clarke AF.Exercise induced pulmonary haemorrhage (EIPH) is a condition of uncertain aetiology. This article reviews the evidence relating to its incidence, clinical findings, radiological observations, histopathology and certain aspects of respiratory physiology. It is proposed that EIPH is primarily caused by mechanical stress in the dorsocaudal region of the lung.
Lyons ET, Tolliver SC, Drudge JH, Swerczek TW, Crowe MW.Prevalence of natural infections of parasites from the lungs of 488 dead Thoroughbreds in Kentucky was investigated. The horses varied from 1 to 32 years of age; 419 horses were from 215 farms and 69 horses were from 68 individual sources for which a specific farm was not identified. Examinations of the lungs were made from Mar 1, 1983 through Feb 29, 1984. Dictyocaulus arnfieldi was recovered from 56 (11%) of the horses. Other parasites found were larvae of Parascaris equorum in 37 (8%) and of Habronema/Draschia in 67 (14%) of the horses. The possible effect of ivermectin treatment on the pre...
Mirbahar KB, McDonell WN, Bignell W, Eyre P.Pulmonary function tests were performed in seven conscious, standing horses. Changes in pulmonary mechanics and ventilation volumes were measured after inhalation challenge with saline (baseline), histamine (1% w/v solution for 5 min) and carbachol (0.5% w/v solution for 3 min). Comparisons between baseline and posthistamine values revealed a significant (P less than 0.05) increase in nonelastic work of breathing (Wb), maximum change in transpulmonary pressure (max delta Ppl), and pulmonary resistance (RL), while dynamic compliance (Cdyn) decreased (P less than 0.05). Tripelennamine completely...
Dobson A, Gleed RD, Meyer RE, Stewart BJ.The distribution of blood flow to the lungs was measured with labelled microspheres injected into horses before and during anaesthesia. Anaesthesia was induced with glycerol guaiacolate ether and ketamine, and maintained with the spontaneous breathing of halothane in oxygen. In a preliminary group of six horses, flow distribution was observed during anaesthesia in sternal, dorsal and right lateral recumbency. In two other groups, each of four horses, the flow distribution with time during either sternal or right lateral recumbency was observed. A small, constant proportion of the 15 micron dia...
Lyons ET, Tolliver SC, Drudge JH, Swerczek TW, Crowe MW.A total of 89 Thoroughbreds, 14 to 333 days old (born in 1982), were examined at necropsy for certain internal parasites during a 1-year-period, Mar 1, 1982, to Feb 28, 1983. The eyes of 73 of the horses and the cranial mesenteric arteries of 71 were examined. Specific interest was on prevalence of parasites according to month of the year and age of the horses at necropsy. Parasites recovered (first month-last month infected horse found) were as follows: Thelazia lacrymalis (eyes) immature and mature (June - February); Habronema/Draschia (lungs) immature (May - September); Habronema muscae (st...
Derksen FJ, Robinson NE, Armstrong PJ, Stick JA, Slocombe RF.We measured lung function and airway reactivity to histamine administered by aerosol in two groups of ponies. Principal ponies had a history of heaves, a disease characterized by recurrent airway obstruction when ponies are housed in a barn and fed hay; control ponies had no history of airway obstruction. Ponies were paired (principal and control) and measurements were made when principal ponies were at pasture and in clinical remission (period A), following barn housing when principal ponies had acute airway obstruction (period B), and after a further 1 and 2 wk at pasture (periods C and D). ...
Becker GM, Nocerini MR, Carlson JR, Breeze RG.Autoradiographs of horse-lung explants incubated with [3H]3-methylindole (3MI) showed 8 times greater labeling per area to bronchiolar epithelial cells than to the interalveolar septa. Incubations of horse-lung microsomes with [14C]3MI resulted in alkylation of microsomal proteins, which could be reduced by exogenous glutathione. An apparent covalent adduct of glutathione and 3MI was isolated from these incubations. These results suggest that the target cells of 3MI-induced injury in the horse, the bronchiolar epithelial cells, are alkylated by an electrophilic 3MI intermediate.
Whitwell KE, Greet TR.A flexible endoscope was used to obtain 223 tracheal washes from 191 horses in three clinical categories. Total cell counts, cytological and bacteriological examinations are reported and the features of the main cell types encountered described. The presence and degree of inflammatory airway disease was determined by a semiquantitative assessment of the neutrophil response and was an important consideration in the interpretation of the bacteriological results. Potential pathogens were isolated from approximately 30 per cent of samples. Cytological changes suggestive of lungworm infestation, vi...
Mason DK, Collins EA, Watkins KL.An investigation into the incidence of exercise induced pulmonary haemorrhage (EIPH) in thoroughbreds in Hong Kong was carried out between the 1981 and 1983 racing seasons. A total of 1039 post race endoscopic examinations were performed in 1982-1983 and the results indicated that 46.8 per cent of runners had EIPH. This was not statistically different from the percentage of horses showing EIPH during 1981-82 (46.9 per cent). As it had been postulated that dust, especially from straw, could be implicated in lung haemorrhage a proportion of horses were bedded on paper in the 1982-83 season. No s...
Anderson GF, Landsheft B.Performance horses should be thoroughly examined before sale to detect any defects that could render them unsuitable for the purchaser's intended use. With the horse in its stall, the eyes, nasolacrimal puncta, external ear canals and mouth are examined, the rectal temperature measured and the heart, lungs, trachea and sinuses auscultated. Moving the horse out of the stall, the head, parotid glands, mandibular lymph nodes, larynx, neck muscles, jugular veins and cervical vertebrae are inspected. The scapula, point of the shoulder, withers, tuber sacrale and point of the hip are palpated, after...
Amis TC, Pascoe JR, Hornof W.The regional distribution of ventilation to perfusion ratios (VA/Q) in the lungs of 8 healthy standing Thoroughbred geldings (4.4 +/- 1.5 years, 465.7 +/- 46.6 kg) was studied, using steady-state inhalation and IV infusion of the radioactive gas krypton-81m. The VA/Q was uniformly distributed within a vertical lung strip centered over the 9th rib on the right side. Ventilation per unit of alveolar volume (V/VA) assessed from the clearance of inhaled radioactive gas in 5 horses increased from 0.49 +/- 0.13 (arbitrary units) in nondependent lung zones to 1.45 +/- 0.16 in dependent lung zones. Se...
Miller PJ, Holmes JR.The relationship of the scalar and vector magnitudes of the QRS waveform to RR, PR and respiration was examined in 10 horses in regular rhythm using an orthogonal lead system. There were no significant changes in the durations of RR and PR with respiration. The amplitudes of the scalar variables XR and YR were directly related and that of XQ (or XS) and ZR were inversely related to PR in this group of horses. The peak spatial vector magnitude and its H-plane angle were directly related to PR and inversely related to RR. The effect of inspiration on the QRS was a decrease in YR and ZR, an incre...
Zink MC, Johnson JA.Bronchoalveolar lavage was performed 5 times, sequentially, on 3 healthy foals when each was between 2 and 63 days of age. Total and differential counts were performed on recovered cells. The lungs of foals less than 19 days of age contained few alveolar macrophages recoverable by bronchoalveolar lavage. This number increased sharply during the first 2 to 3 weeks of life, but remained relatively constant subsequently. Approximately 86% of the alveolar cells in the lungs of foals up to 3 weeks of age were alveolar macrophages. During the first 2 months of life, this number decreased to approxim...
Breeze RG, Legreid WW, Bayly WM, Wilson BJ.Perilla ketone was assessed for its usefulness as a model of equine restrictive pulmonary disease. Three ponies were given 18 mg/kg bodyweight synthetic perilla ketone in dimethyl-sulphoxide. Within 24 h of administration, respiratory rate, peak inspiratory and expiratory flow rates and minute volume were increased. By 48 h there was a significant decrease in tidal volume, and blood pH and base excess were also decreased but not outside normal limits. At necropsy there was congestion and oedema of the lungs. Histologically there was diffuse alveolar injury but no evidence of significant obstru...
Breeze RG, Brown CM, Turk MA.3-methylindole was administered orally and intravenously to horses and ponies in order to determine the ability of this chemical to provide a model of equine pulmonary disease. Both routes produced a severe and sometimes fatal pulmonary disease, characterised by bronchiolitis. Clinical signs developed 48 to 72 h after dosing and were most severe between Days 4 and 10 post dosing. Intravenous administration of 3-methylindole produced lung injury more rapidly and at a lower dose rate than the oral route. It is suggested that the respiratory condition induced by this chemical could become a metho...
Dyer RM, Liggitt HD, Leid RW.A device was constructed from an equine nasogastric tube, polyethylene tubing, and a 3-way stopcock and used to lavage the lungs of anesthetized ponies. The technique was safe and atraumatic in that 6.4 to 19.7 X 10(7) purified alveolar macrophages were removed from the lungs without harm to the ponies or contamination of the samples with blood. Studies of these highly purified cell suspensions revealed a mean viability of 85% as assessed by eosin dye exclusion with a mean recovery (+/- SD) of 12.5 +/- 4.8 X 10(7) pulmonary alveolar macrophages/pony.
Sabine M, Feilen C, Herbert L, Jones RF, Lomas SW, Love DN, Wild J.Until 1977 no case of abortion caused by equine herpesvirus 1 (EHV1) had been recorded in Australia although the virus, called equine rhinopneumonitis virus, had been known to have been present at least since 1962. Outbreaks of EHV1 abortion occurred in New South Wales in 1977 and in 1981. Sporadic cases of EHV1 abortion had been confirmed in some parts of Australia each year since 1975. It was concluded that an abortigenic subtype of EHV1 had been introduced to Australia in 1977 and that the previously endemic respiratory subtype occasionally caused abortion. Virus isolation in a variety of c...
Reitsma JF.A report on infection with Dictyocaulus arnfieldi in a number of ponies and one horse in which complete clinical recovery was obtained following treatment with albendazole (Valbazen), administered by oral route at a dosage of 25 mg/kg of body weight twice daily for five days.
Johnson JA, Prescott JF, Markham RJ.Six foals were inoculated intrabronchially with a suspension of Corynebacterium equi. Six weeks before this challenge, three foals were vaccinated with a C. equi bacterin. Three foals were unvaccinated controls. All foals developed a severe bronchopneumonia in the inoculated lung, indicating that vaccination was not protective. Three foals (two vaccinated, one control) were killed eight to nine days after infection. One control died on day 9 with lesions of disseminated intravascular coagulation. The remaining two foals (one vaccinated, one control) were killed on day 17. C. equi was cultured ...
Newsholme SJ.Gross, histological and ultrastructural findings are described in 6 natural cases and in 2 experimental cases of African horsesickness. From the gross lesions the cases were divisible into 2 groups which represented the previously described pulmonary and mixed forms of the disease. Histologically, abundance of fibrin and inflammatory cells in oedematous lung suggests that the pulmonary lesion is an exudative pneumonia. Lymphoid depletion and necrosis in germinal centres were consistently present. Electron microscopy failed to demonstrate virus particles or virus-associated structures in the ti...
Rice DA.The time it takes audible sound waves to travel across a lobe of excised horse lung was measured. Sound speed, which is the slope in the relationship between transit time and distance across the lobe, was estimated by linear regression analysis. Sound-speed estimates for air-filled lungs varied between 25 and 70 m/s, depending on lung volume. These speeds are less than 5% of sound speed in tissue and less than 20% of sound speed in air. Filling the lung with helium or sulfur hexafluoride, whose free-field sound speeds are 970 and 140 m/s, respectively, changed sound speed +/- 10% relative to a...
Roberts MC, Seawright AA, Ng JC, Norman PD.Chronic mercuric chloride intoxication in an aged horse given 0.8 mg Hg/kg/day for 14 weeks was manifest by signs of progressive respiratory difficulty and renal disease. The effects were not self-limiting after mercury was withdrawn, and the animal was destroyed six weeks later. Renal function changes included heavy glycosuria, modest proteinuria, phosphaturia, reduced urine osmolality, gradually increasing urine production, reduced glomerular filtration rate, and terminally, azotemia. The condition bore similarities to the Fanconi syndrome in man. Urinary gamma-glutamyl transpeptidase, alkal...
Derksen FJ, Slocombe RF, Robinson NE.In standing sedated ponies, we measured dynamic lung compliance (Cdyn) and pulmonary resistance (RL) during IV infusion of various doses of histamine; this was done in a given pony 3 times at 1-week intervals between experiments. Histamine doses causing a decrease in Cdyn of 50% and 75% and an increase in RL of 300% and 600% (ED50Cdyn, ED75Cdyn, ED300RL and ED600RL, respectively) were interpolated from the histamine dose-response curves. We also measured respiratory frequency, tidal volume, minute ventilation, functional residual capacity, arterial oxygen tension, arterial carbon dioxide tensi...
Wilkie BN.Effective resistance to respiratory tract infection depends principally on specific immunity on mucosal surfaces of the upper or lower respiratory tract. Respiratory tract immune response comprises antibody and cell-mediated systems and may be induced most readily by surface presentation of replicating agents but can result from parenteral or local presentation of highly immunogenic antigens. Upper and lower respiratory tract systems differ in immunologic competence, with the lungs having a greater inventory of protective mechanisms than the trachea or nose. Several effective vaccines have bee...
Raphel CF, Beech J.Of 122 horses with pleural effusion, 90 (73.8%) had pleuritis secondary to pneumonia or lung abscessation. Fifty-one horses died or were euthanatized. The highest prevalence was in Thoroughbred and Standardbred racehorses. Eleven (12.2%) horses were postsurgical patients and 22 (24.4%) horses had been transported over 500 miles. There was no relationship between final outcome and the age, sex, breed, hematologic values, or laboratory findings pertaining to pleural fluid except for the bacterial isolation of Escherichia coli from the pleural fluid, as this was more frequently associated with de...
Goncarovs KO, Miskovic Feutz M, Perez-Moreno C, Couetil LL.One proposed nonmedical therapy for recurrent airway obstruction (RAO) in horses is a handheld acoustic device that propels sound waves from the nose down the tracheobronchial tree where it is intended to dislodge mucous and relax bronchospasm, permitting clearance of mucoid secretions. Objective: To evaluate the effectiveness and safety of this device when used as per the manufacturer's recommendations as a treatment for RAO. Methods: Nine adult horses previously diagnosed with RAO. Methods: Prospective, cross-over clinical trial. Horses were exposed to a dusty environment until airway obstru...
Nickels FA, Brown CM, Breeze RG.A unilateral pulmonary granular cell tumor occurred in a Thoroughbred mare with longstanding respiratory disease wrongly attributed to chronic obstructive pulmonary disease. The clinical features, radiology and endoscopic appearance permitted an accurate diagnosis, which was supported by subsequent necropsy and histologic examination. Obstructive pulmonary disease was ruled out after measurement of arterial blood gases and maximum intrathoracic pressure changes, and after microscopic examination of the lung.
Seither RL, Brown OR, Babu BV.Rat, cow and foal lung extracts contained an inhibitor for the liver NAD biosynthetic-pathway enzyme, nicotinatemononucleotide pyrophosphorylase (carboxylating) [EC 2.4.2.19]. The inhibitor was not dialyzable, was labile at 100 degrees C, was retained by a 30,000 dalton pore size Amicon membrane and, when partially purified by precipitation at 40-100% ammonium sulfate, inhibited the enzyme stoichiometrically. Lung reportedly does not contain nicotinate-mononucleotide pyrophosphorylase or make NAD de novo. However, the inhibitor would mask detection of the enzyme in lung extracts. We detected a...
Hillidge CJ, Whitlock TW.Post race endoscopy was carried out on 255 two-year-old quarter horses and exercise-induced pulmonary haemorrhage (EIPH) was diagnosed in 166 (65 per cent) of them. Visible epistaxis was seen in a higher proportion of geldings than in either mares or stallions. The prevalence of EIPH was similar in mares (73 per cent) and in geldings (74 per cent). A significantly lower prevalence (49 per cent) was noted in stallions (P less than 0.01). It was concluded that a sex variation in the prevalence of EIPH exists in two-year-old quarter horses.
Gudmundsson G, Olafsson L, Nikulásson S, Jónsdóttir B.A young woman was admitted to Akranes Regional Hospital because of dyspnea, fatigue and fever. She was found to have bilateral pneumonia but etiology was not found. She was treated with antibiotics with good resolution and was discharged after eight days from the hospital. Four weeks later she noticed rapidly progressive dyspnea and was found to be hypoxemic, and to have restrictive spirometry and diffuse interstitial changes on chest radiography. Computerized tomography of the lungs showed diffuse ground glass changes. Transbronchial biopsies from the lungs showed numerous small granulomas. S...
Urch DL, Allen WR.The efficacy of orally administered fenbendazole on lung and intestinal parasitism in equids was investigated in a mixed herd of pony mares, jenny donkeys and foals. A single dose of 7.5 mg fenbendazole/kg body weight effectively removed intestinal parasites from the ponies, donkeys and foals, but higher doses and repeated treatments failed to eliminate lungworm infections in donkeys. The finding of eosinophilia proved useful in detecting lungworm infections in donkeys.
Townsend M, Fowler B, Aulakh GK, Singh B.Endotoxin-induced diseases cause significant mortality and morbidity in the horse, leading to enormous economic damage to the equine industry. Neutrophils play a critical role in initiating the immune response in the lung. Pattern recognition receptors (PRRs) are programmed to recognize microbial structures unique to pathogens and mount an immune response. Pentraxin 3 (PTX3) is a PRR that is produced at sites of inflammation by many cell types upon stimulation by pro-inflammatory cytokines and agonists, such as endotoxins [also known as lipopolysaccharides (LPS)]. Pentraxin 3 recognizes and bi...
Attenburrow DP, Flack FC, Portergill MJ.The technique of impedance plethysmography is described and its application to observation of lung volume changes in the horse at exercise is discussed. The results from horse at rest show that there is a close relationship between rate of lung volume change (flow rate) and the associated impedance changes during both inspiration and expiration. Impedance changes during exercise were related to inspiration and expiration by observation of associated respiratory sounds. Artefacts related to technical difficulties are also indicated.
Robinson NE.The primary function of the equine respiratory system is the exchange of oxygen and carbon dioxide at a rate that is matched to metabolism. Gas exchange requires ventilation, distribution of gas within the lung, perfusion of blood through pulmonary capillaries, matching of ventilation and blood flow, diffusion of gases between air and blood, and transport of gases to and from the muscles. In this article, the author reviews what is known about each of these processes in the resting and exercising horse.
Facemire PR, Chilcoat CD, Sojka JE, Adams SB, Irizarry AR, Weirich WE, Morisset SS, Dutweiler VA.A 7-year-old warmblood mare was referred because of a respiratory tract disorder; pulmonary granular cell tumor was diagnosed. Pulmonary granular cell tumor is a locally invasive but rare type of tumor with low metastatic potential. The entire right lung was resected to ensure removal of all neoplastic tissue. The horse recovered well and has minimal difficulties functioning with one lung. Most of these tumors are diagnosed during postmortem examination. To our knowledge, this is the first report of pulmonary granular cell tumor treated by complete lung resection in a horse.
Breeze RG, Brown CM, Turk MA.3-methylindole was administered orally and intravenously to horses and ponies in order to determine the ability of this chemical to provide a model of equine pulmonary disease. Both routes produced a severe and sometimes fatal pulmonary disease, characterised by bronchiolitis. Clinical signs developed 48 to 72 h after dosing and were most severe between Days 4 and 10 post dosing. Intravenous administration of 3-methylindole produced lung injury more rapidly and at a lower dose rate than the oral route. It is suggested that the respiratory condition induced by this chemical could become a metho...
Richards KS, Ilderton E, Yardley HJ.Lipids extracted from the laminated layers of horse liver and lung hydatids, including a daughter liver cyst, were analysed using TLC. No differences in lipid composition was detected in 11 liver cysts, whether from the same or different livers, and di- and triacylglycerols, cholesterol, wax and steryl esters, oleic acid, sphingomyelin, phosphatidyl choline, phosphatidyl inositol and ceramide hexosides were detected. The daughter cyst differed from its "parent" cyst in lacking diacylglycerols and wax and steryl esters. The lung cyst differed from the liver cysts in that cholesterol, wax and st...
Clarke AF.Exercise induced pulmonary haemorrhage (EIPH) is a condition of uncertain aetiology. This article reviews the evidence relating to its incidence, clinical findings, radiological observations, histopathology and certain aspects of respiratory physiology. It is proposed that EIPH is primarily caused by mechanical stress in the dorsocaudal region of the lung.
Epe C, Bienioschek S, Rehbein S, Schnieder T.Genomic DNA isolated from the four Dictyocaulus species D. viviparus, D. eckerti, D. filaria and D. arnfieldi was compared by random amplified polymorphic DNA polymerase chain reaction (RAPD)-PCR to get additional information whether lungworms from fallow deer belong to a separate species (D. eckerti) or have to be regarded as an isolate of D. viviparus in wild ruminants. The resulting banding patterns of the electrophoresed PCR products were compared to assess the degree of genetic differences between the different lungworms. For the two D. viviparus isolates a similarity coefficient of 93.4%...
Hobo S, Hiraga A, Birks EK, Takahashi T, Hada T, Jones JH.A study was undertaken to find if the reason why horses hypoventilate when running is that they experience expiratory flow limitation due to dynamic airway closure. To test this hypothesis, we measured peak expiratory flows on a Thoroughbred galloping on a treadmill and hypoventilating and compared those flows with the peak dynamically-limited flow that the same horse could achieve during a forced expiratory flow-volume manoeuvre. At the approximate lung volumes at which the horse was ventilating while running, it did not appear to be mechanically limited and appeared to have reserve capacity ...
Maier-Bock H, Ehrlein HJ.During a gradually increasing exercise test heart rates were determined in healthy animals and in 2 groups of sick horse. These included 31 animals with a chronic pulmonary disorder and 5 with chronic heart disease. The alteration in heart rate was correlated with the clinical signs exhibited. In the horses with lung disease there was a close correlation between the stage of the diseases and the heart rate during the exercise test. In 3 animals with heart valve disease there was no apparent difference in heart rate compared with healthy horses. On the other hand the exercising heart rate of ho...
Olson NC.Effects of endotoxemia on lung water, hemodynamics, and gas exchange were determined in ponies breathing a mixture of halothane and 100% O2. Escherichia coli endotoxin was infused IV at 20 micrograms/kg of body weight for 1 hour followed by 10 micrograms/kg/hr the subsequent 4 hours. By 0.25 hour, endotoxin increased mean pulmonary artery pressure and pulmonary vascular resistance; this was followed by a return to base-line values by 0.5 and 1 hour, respectively. A 2nd increase in pulmonary vascular resistance occurred by 5 hours of endotoxemia. During the last 2 hours of endotoxin infusion, c...
Sweeney CR, Weiher J, Baez JL, Lindborg SR.The endobronchial anatomy of 12 lung specimens from horses and 12 healthy, standing, sedated horses was evaluated, using a 200-cm-long, 9.5-mm-diameter videoendoscope. On the basis of these findings, the nomenclature system of Amis and McKiernan was modified for identification of airways of horses during bronchoscopy. Lobar bronchi are identified on the basis of the side of the bronchial tree on which they were found and the order in which they originated from the primary bronchus. Thus, RB1, RB2, and RB3 referred to right cranial lobar bronchus, respectively. On the left side, the designation...
O'Callaghan MW.When performed on selected clinical cases, ventilation/perfusion scintigraphy provides valuable additional information on regional lung function that is not obtainable from conventional thoracic radiographs. This is particularly true of horses with EIPH, COPD, and those suspected of having some form of small-airway disease. For horses with EIPH, the presence of a perfusion deficit on the scan is considered a key prognostic sign, because it is likely in these cases that irreversible bronchial arterial takeover has occurred in the affected areas of lung. Findings from horses with COPD have impro...
Arthur RM.Racetracks are ideal environments for the promotion of lower respiratory disease. The stabling is close and unclean, the population is nationally and internationally mobile, and the work the racehorse performs is traumatic to the respiratory tract. The running horse must complete a respiratory cycle with each stride. This relationship requires 130-150 breaths a minute in the running horse. Minute volume has been measured at 1300 L per minute and peak flow rates of 60 L/second in horses traveling at a modest 8 meters per second. As a comparison, the fastest running horse approaches 18 meters pe...
Sweeney CR, Tomasic M, Russell GE.The effect of inhaled nitric oxide on pulmonary mechanics was studied in normal standing horses with histamine-induced bronchoconstriction. The respiratory health status of 6 normal horses was established on the basis of history, clinical and bronchoalveolar lavage examination. Intrathoracic pressures were estimated using distal oesophageal pressures. Respiratory gas flows were measured using a heated pneumotachograph. Pulmonary mechanics variables were determined from these measurements on a breath by breath basis. Bronchoconstriction was induced by nebulizing a 0.75% w/v solution of histamin...
Ainsworth DM, Ducharme NG, Hackett RP, Eicker SW, Snedden K.We examined the electromyographic activity of the costal portion of the diaphragm and the transverse abdominal and external oblique muscles in 6 chronically instrumented awake adult horses during eupneic breathing, during 2 levels of hypercapnia (fractional concentration of inspired CO2; FICO2 = 0.4 and 0.6), and during 2 levels of hypocapnic hypoxia (FIO2 = 0.15 and 0.12). Using the inert gas technique, we also measured the end-expiratory lung volumes of the 6 horses during eupnea, 6% CO2 challenge, and 12% O2 breathing. During eupneic breathing, phasic electrical activity of these 3 muscles ...
Marr KA, Lees P, Page CP, Cunningham FM.The leukotrienes (LT) LTD4 and LTB4 have been shown to cause bronchoconstriction and neutrophil accumulation, respectively, in horse lungs. Such changes are characteristic of the equine allergic respiratory disease, chronic obstructive pulmonary disease (COPD). To further investigate the role of these putative mediators in the pathogenesis of equine COPD the effect of a 5-lipoxygenase inhibitor, fenleuton, on antigen-induced changes in horses with this condition has been examined. Six horses with COPD underwent a series of four antigen challenges, one month apart, with placebo pre-treatment on...
Simpson CF, Buergelt CD.The alveoli of the lungs of 2 aborted foals contained elongated, dense bodies when examined histologically and by transmission and scanning electron microscopy. By light microscopy, the bodies (10 to 40 micrometers in size) stained intensely with the Gram stain, and up to 10 were present within an alveolus. Electron microscopy determined that such bodies were not cellular in origin but appeared to be a congealed fluid product composed of layers of fibrillar-like material. From the human literature, it was concluded that these intraalveolar bodies were probably congealed amniotic fluid.
Winder NC, von Fellenberg R.In lungs from 22 horses, the number and type of mast cells in histologically normal specimens were compared with those in specimens with various histological lesions. Tissues fixed in Carnoy's solution were superior to those fixed in formalin for the identification of mast cells. Fixation of lung specimens from eight horses in Carnoy's solution and formalin allowed the identification of two subpopulations of mast cells: formalin-sensitive, which predominated and formalin-resistant. Specimens with mild chronic tracheitis and mild and moderate chronic bronchitis generally had slight increases in...
Liu IK, Walsh EM, Bernoco M, Cheung AT.Two bronchoalveolar lavages, 24 h apart, were performed on 15 foals, ranging in age from 1 to 21 days. In the first lavage, a numerical deficiency in alveolar macrophages was demonstrated in foals up to 2 weeks of age when compared with older (2-3 years of age) horses. Alveolar macrophages obtained from the lungs of 2-3-day-old foals also demonstrated significant impaired chemotactic function. In the second lavage, although an increase of alveolar macrophages was noted, a dramatic increase of polymorphonuclear neutrophil (PMN) mobilization occurred in the foals, thus providing a phagocytic bac...
Lakritz J, Wisner ER, Finucane T, O'Brien TR, Tyler WS, Pascoe JR, Plopper CG.Interstitial and bronchointerstitial pulmonary patterns are commonly observed in thoracic radiographs of Thoroughbreds. Prominent interstitial and bronchointerstitial pulmonary patterns are observed in clinically normal horses, and in horses with respiratory tract disease. Until recently, the relevance of these pulmonary patterns was not known. Previous studies indicated that bronchiolitis, bronchiolar epithelial hyperplasia, epithelial metaplasia, and bronchial arteriolar recruitment correlated strongly with the prominence of the interstitial and bronchointerstitial pulmonary patterns observe...
Townsend KS, Johnson PJ, Kuroki K.Primary squamous cell carcinoma of the head and neck occurs in the skin or squamous epithelial lining tissues of the oral cavity, pharynx, larynx, and sinonasal tract. Although it is a common tumor in horses, distant metastatic spread to the lung is rare. This report describes a case of metastatic pulmonary squamous cell carcinoma in a 23-year-old Morgan gelding. The clinical signs displayed by this gelding in some ways mimicked the typical presentation of equine multinodular pulmonary fibrosis or thoracic lymphoma. The postmortem diagnosis in this case was head and neck squamous cell carcinom...
Hoffman AM, Viel L, Staempfli HR, Muckle CA, Yager JA.One indication for referral of horses to veterinary hospitals is for diagnosis of the microbiologic cause of pneumonia, particularly when the initial treatment fails. Although endoscopic methods have long been available for microbiologic sample collection, accuracy of these methods under these conditions have not been studied in detail. We compared the bacteria isolated from samples obtained by bronchoalveolar lavage (BAL) with those obtained by protected catheter brush (PCB) from foals with unilateral pneumonia induced by inoculation with Klebsiella pneumoniae. As part of previously described...
Koterba AM, Wozniak JA, Kosch PC.This study investigated the developmental changes in the mechanical properties of the respiratory system in growing horses. Pulmonary mechanics and lung volumes were serially measured in anesthetized foals during the first year of life. Quasi-static pressure-volume curves were generated, and functional residual capacity (FRC) was measured using a closed nitrogen equilibration technique. At birth, chest wall compliance normalized to body weight was substantially less than that reported in other less precocious newborn species, while lung compliance normalized to body weight was similar to value...
