• Higher prevalence in older horses – Increased speed of racing 3 EIPH – Etiology • Several proposed mechanisms • • • • Pulmonary hypertension Disruption in coagulation Neovascularization 2ndary to inflammation Increased intrathoracic forces during exercise (mechanical stresses) • Small airway disease • Upper airway obstruction • Redistribution of blood flow in the lung We don’t really know–could be a combo or it could be that multiple causes lead to same outcome (usually in dorsal caudal lung fields, possibly due to abdominal pressure on lungs) EIPH – Etiology • Etiology – Alveolar capillary membranes rupture • Bleeds into interstitial and alveolar spaces due to shear and tear forces – Repeated bouts of hemorrhage lead to small airway inflammation and interstitial fibrosis – Once bronchial arterial neovascularization occurs, contributes to bleeding in airways Question • The majority of horses with EIPH exhibit epistaxis – A.
True – B.
False 4 EIPH – Clinical Signs • Poor Performance • Epistaxis – Epistaxis noted usually at end of race • • • • Head lowered Bilateral Resolves within hours Can occur more than once and often does…. Horse slows Gurgly noise EIPH – Diagnosis — Arytenoid Chondritis 12 Rare infectious inflammatory condition, could also be due to trauma Arytenoid Chondritis • Chronic inflammation of arytenoid cartilages leading to laryngeal obstruction • Trauma, inflammation, infection • Airway obstruction caused by enlarged arytenoid cartilages • Usually unilateral • Progressive and Debilitating Could be due to shear forces causing microlesions in the arytenoids, and bacteria can get in to the cartilage structures of larynx and cause chronic, slow growing infection or inflammation => dystrophic mineralization and necrosis Is a space occupying lesion that will interfere with airflow in trachea Noise is one of first signs Can lead to exercise intolerance as mass gets larger Arytenoid Chondritis • Clinical signs most common – Exercise intolerance – Inspiratory Stridor – Dyspnea at rest in severe cases Severity of signs depends on size of obstruction May see contact lesion on contralateral side May see focal mineralization on rads Ddx: neoplasias like SCC or lymphosarcoma Coughing • Diagnosis – Endoscopy – Radiographs Arytenoid Chondritis • Treatment — Laryngeal Hemiplegia • Condition resulting from damage to left recurrent laryngeal nerve (LRN) – Idiopathic Especially in tall warmblood horses >16 hands; rare in ponies Stallions & geldings (pushed to grow more quickly) are more susceptible than mares Usually on left side, possibly due to longer recurrent laryngeal nerve on that side Usually idiopathic Generally worsens over time, possibly congenital (has been identified in foals and fetuses) • LRN – Innervates the muscles of the larynx • Cricoarytenoideus dorsalis (abductor) • Trauma, guttural pouch mycosis, neoplasia, organophosphate poisoning, lead poisoning, toxic plants Larnygeal Hemiplegia • Fun Facts – Has been identified in foals and fetuses – Horses >16 hands most susceptible • Rarely seen in ponies If toxin is cause, both sides should be affected – Stallions and geldings > risk than mares 14 Laryngeal Hemiplegia • Clinical Signs – Reduced performance of high performing horses – “Roarers”
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