![]() Other possible tests are high resolution ECG, postural test and electrophysiological studies. Therefore, an ECG and echocardiographic evaluation are indicated. Boxers and Dobermans are predisposed to dilated/ arrhythmogenic cardiomyopathy, with risk of sudden death. In this case, an ECG is also required, including a Holter monitoring, in order to evaluate the possibility of arrhythmias. If a loud systolic murmur over the aortic valve area is auscultated, a diagnosis of subaortic stenosis should be considered, and an echo will be necessary to confirm the diagnosis and determine the severity. If the animal presents pale mucous membranes, differentiation between anemia and vasoconstriction should be done. Questions regarding the use of drugs, which may contribute to syncope as vasodilators, beta-blockers, diuretics, insulin, etc.ĭepending on animal characteristics (signalment), history and physical exam results, the diagnostic tests are performed to confirm or to eliminate certain causes. The clinical approach to the patient with a history of syncope requires a detailed history, complete physical examination, and other exams, which include complete blood count, biochemical profile, potassium and glucose determination, electrocardiogram, blood pressure, echocardiogram. Other causes related to syncope in dogs: respiratory diseases(tracheobronchial and pulmonary diseases, upper airway diseases), metabolic and hematological diseases (anemia, hyperadrenocorticism, hypoadrenocorticism, GI diseases, neurological diseases) ![]() Chronic respiratory diseases and resultant hypoxemia and pulmonary hypertension are also possible causes of syncope. In patients with hypoadrenocorticism it may result from hypovolemia and hypoglycemia. Syncope secondary to anemia, blood hyperviscosity, hypoglycemia, hypoxia. It may be triggered by specific situations as cough, micturition, defecation, pain, emotion, agitation, exercise, use of slip collar. Pathophysiology of neurocardiogenic bradycardia is unclear, but in people, it is described as caused by an autonomic reflex, leading to a bradycardia, in the presence of vasodilation or hypovolemia. There are evidences of the occurrence of this type of syncope in animals, but the mechanism is not well established. ![]() Neurocardiogenic syncope-also called neurally mediated bradycardia, cardioneurogenic syncope, vasodepressor syncope, reflex syncope or vasovagal syncope-apparently, this is the most common diagnosed cause in humans. Hypotension syncope-may be caused by the use of drugs that alter vascular responsiveness (vasodilators), hypovolemia caused by blood loss, plasma volume reduction secondary to excessive diuretic use or gastrointestinal problems (diarrhea, vomiting). Pre-syncope is characterized by a transient wobbling and weakness of rear limbs, without loss of consciousness, caused by a slight decrease in brain perfusion.Ĭardiogenic syncope-results from incapacity to adequate cardiac output (CO), as a result of myocardial failure, valvular insufficiency, bradyarrhythmias (sinus arrest, complete atrioventricular block) or tachyarrhythmias (supraventricular and ventricular), sick sinus syndrome, difficulty in ventricular filling (cardiac tamponade, intracardiac masses), outflow obstruction (hypertrophic cardiomyopathy with anterior motion of mitral valve, subaortic stenosis, pulmonic stenosis), cyanotic congenital heart diseases, pulmonary thromboembolism, pulmonary hypertension, heartworm disease. Seizure, more commonly leads to tonic-clonic muscle contractions, with a longer duration (over a minute), may present some pre-ictal behavior change, a slower return to normal and some degree of neurological post-ictus compromise. Typically, syncope has a short duration (less than 1 minute), results in consciousness loss, flaccid paralysis or limb spasticity, and sometimes, opisthotonos (condition of abnormal posturing that involves rigidity and severe arching of the back, with the head thrown backward) and vocalization. Syncope must be differentiated from seizure. There are several possible causes for a syncope episode among them are cardiovascular, metabolic, respiratory and neurological origins. Therefore, the main cause must be determined to perform the best management. Syncope is a clinical sign, not a disease. It is the result of an abrupt reduction of oxygen and/or glucose delivery to the brain, essential substrates for the oxidative metabolism. ![]() Syncope may or may not be associated with urine and feces elimination. Syncope or fainting is a sudden and transient (brief) loss of consciousness associated with loss of postural tone, followed by a spontaneous recovery. Most of the times, by the arrival at the hospital, the animal is conscious and looks healthy, and often, without any alterations that immediately explain the syncope episode. Syncope complaint is always scary for the owner, and a puzzle for the veterinarian. ![]()
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