Differential diagnosis for more common causes of episodic weakness and collapse (note: this is not an exhaustive or complete list).


Cardiac diseases
Dysrhythmias
Bradyarrhythmias
sinus arrest
2nd or 3rd degree heart block
Tachydysrhythmias
supraventricular tachycardia
ventricular tachycardia
Forward failure on exertion
Defects producing severe obstructive outflow tract defects
subaortic stenosis
pulmonic stenosis
hypertrophic obstructive cardiomyopathy (H 0CM)
Animals with poor diastolic filling
pericardial tamponade
Animals with advanced heart failure with poor cardiac output of any cause
dilated cardiomyopathy
valvular endocardiosis and ruptured chordae tendineae
Right to left congenital cardiac shunts
PDA or VSD with Eisenmenger's physiology
tetralogy of Fallot
Heartworn disease
Angiostrongylosis Dirofilariasis
Vasovagal syncope


Respiratory diseases
Respiratory distress and hypoxaemia
Upper airway obstruction
brachycephalic airway syndrome
laryngeal paralysis
tracheal collapse
hypoplastic trachea
foreign body obstruction proximal to carina
Severe lung parenchymal diseases
chronic pulmonary interstitial disease
diffuse neoplastic involvement
severe pulmonary thromboembolism
Restriction of lung compliance
pleural effusion
pneumothorax
Tussive syncope


Endocrine/metabolic disorders
Hyperkalaemia
Hypoadrenocorticism (Addison's disease)
Diabetic ketoacidosis
Acute/oliguric renal failure
Obstructive urinary tract disorders
Hypokalaemia
Hypokalaemic myopathy in cats Hypocalcaemia
Hypoparathyroidism
Post-parturient eclampsia
Hypoglycaemia
insulinoma
insulin overdose in diabetes
liver disease or sepsis
Hypothyroidism
Phaeochromocytoma
Hepatic encephalopathy
portosystemic shunts
cirrhosis
Hyperthermia (heat-stroke)


Neurological and neuromuscular disorders
Epileptiform seizures
Epilepsy
CNS tumours
Narcolepsy/cataplexy
Myasthenia gravis
Polymyopathy/polymyositis
Cauda equina syndrome
Wobbler syndrome
Scottie cramp
Episodic falling over in Cavaliers
Labrador and retriever myopathy
Vestibular disease
Cerebellar disease


Haematological disorders
Anaemia or haemorrhage
Haemangiosarcoma
Coagulopathies


latrogenic causes
Drugs
Hydralazine (first dose hypotensive collapse
X agonist sedative combinations
ACP