Anorexia, primary

• Intracranial disease, e.g.
  
  
  
  • Hypothalamic neoplasia

Anorexia, secondary

• Anosmia
  
  
  
  • Chronic rhinitis q.v.
    
  • Nasal neoplasia
    
  • Other nasal disease
    
  • Neurological disease
  
  
• Endocrine disease, e.g.
  
  
  
  • Diabetic ketoacidosis
    
  • Hypoadrenocorticism (D)
  
  
• Fever* q.v.
  
• Gastrointestinal disease q.v., e.g.
  
  
  
  • Gastritis
    
  • Inflammatory bowel disease*
  
  
• Heart disease, e.g.
  
  
  
  • Cardiac failure*
  
  
• Hepatic disease* q.v.
  
• Infection*
  
• Metabolic abnormalities, e.g.
  
  
  
  • Hypercalcaemia q.v.
    
  • Hypokalaemia q.v.
  
  
• Pain*
  
• Pancreatic disease*, e.g.
  
  
  
  • Pancreatitis
  
  
• Renal disease* q.v.
  
• Respiratory disease, e.g.
  
  
  
  • Airway disease* q.v.
    
  • Diaphragmatic hernia
    
  • Pleural effusion* q.v.
    
  • Pneumonia q.v.

Diet

• Recent dietary changes*
  
• Unpalatable diet*

With good body condition

• Chondrodystrophy (normal in many breeds)* (D)
  
• Endocrine disorders
  
  
  
  • Congenital hyposomatotropism (pituitary dwarfism)
    
  • Congenital hypothyroidism

With poor body condition

• Dietary intolerance
  
• Exocrine pancreatic insufficiency*
  
• Inadequate nutrient intake
  
  
  
  • Anorexia q.v.
    
  • Poor-quality diet
    
  • Underfeeding
  
  
• Cardiac disorders, e.g.
  
  
  
  • Congenital
    
  • Endocarditis
  
  
• Endocrine disease
  
  
  
  • Diabetes insipidus
    
  • Diabetes mellitus*
    
  • Hypoadrenocorticism (D)
  
  
• Gastrointestinal disease, e.g.
  
  
  
  • Histoplasmosis
    
  • Obstruction, e.g.
    
    
    
    • Foreign body*
      
    • Intussusception*
    
    
  • Parasites*
  
  
• Hepatic disorders, e.g.
  
  
  
  • Hepatitis q.v.
    
  • Portosystemic shunt
  
  
• Inflammatory disease
  
• Oesophageal disorders, e.g.
  
  
  
  • Megaoesophagus q.v.
    
  • Vascular ring anomaly (e.g. persistent right aortic arch)
  
  
• Renal disease
  
  
  
  • Congenital kidney disease
    
  • Glomerulonephritis
    
  • Pyelonephritis

Cardiovascular dysfunction

• Bradyarrhythmias q.v., e.g.
  
  
  
  • High-grade second-degree heart block
    
  • Sick sinus syndrome (D)
    
  • Third-degree heart block
  
  
• Myocardial failure
  
• Myocardial infarction
  
• Cardiac disease
  
  
  
  • Congenital, e.g.
    
    
    
    • Aortic stenosis (D)
      
    • Pulmonic stenosis (D)
    
    
  • Hypertrophic obstructive cardiomyopathy
    
  • Pericardial effusion* (D)
    
  • Pulmonary hypertension
    
  • Arterial obstruction, e.g.
    
    
    
    • Neoplasia
      
    • Thrombosis
  
  
• Shock q.v.
  
• Tachyarrhythmias q.v.
  
  
  
  • Supraventricular tachycardia*
    
  • Ventricular tachycardia*

Drugs

• Anti-arrhythmics, e.g.
  
  
  
  • Atenolol
    
  • Digoxin
    
  • Propranolol
    
  • Quinidine
  
  
• Sedatives, e.g.
  
  
  
  • Phenothiazines
  
  
• Vasodilators, e.g.
  
  
  
  • ACE inhibitors
    
  • Hydralazine
    
  • Nitroglycerine

Hypoxaemic disease

• Carboxyhaemoglobinaemia
  
• Methaemoglobinaemia
  
• Pleural/thoracic disorders, e.g.
  
  
  
  • Pleural effusion
    
  • Pneumothorax
    
  • Rib fractures
  
  
• Respiratory disease
  
  
  
  • Lower airway, e.g.
    
    
    
    • Pneumonia
      
    • Small airway disease
    
    
  • Upper airway, e.g.
    
    
    
    • Brachycephalic obstructive airway syndrome
      
    • Laryngeal paralysis
      
    • Tracheal collapse
      
    • Tracheal obstruction
    
    
  • Ventilation–perfusion mismatch, e.g.
    
    
    
    • Pulmonary thromboembolism (PTE)
      
    • Lung collapse
  
  
• Right-to-left cardiac shunt, e.g.
  
  
  
  • Reverse-shunting patent ductus arteriosus
    
  • Severe anaemia

Metabolic/endocrine disorders

• Diabetic ketoacidosis
  
• Hypercalcaemia/hypocalcaemia q.v.
  
• Hypernatraemia/hyponatraemia q.v.
  
• Hyperthermia/hypothermia q.v.
  
• Hypoglycaemia q.v.
  
• Hyperkalaemia/hypokalaemia q.v.
  
• Severe acidosis q.v.
  
• Severe alkalosis q.v.
  
• Pheochromocytoma
  
• Hypoadrenocorticism
  
• Insulinoma

Miscellaneous

• Carotid sinus stimulation, e.g.
  
  
  
  • Neoplasia
    
  • Tight collar
  
  
• Hyperventilation
  
• Postural hypotension
  
• Tussive/cough syncope

Myopathies

• Corticosteroid myopathy
  
• Exertional myopathy
  
• Hypocalcaemic myopathy
  
• Hypokalaemic myopathy
  
• Malignant hyperthermia
  
• Mitochondrial myopathy
  
• Muscular dystrophy
  
• Polymyopathy
  
• Polymyositis
  
• Protozoal myopathy

Neurological dysfunction

• Brainstem disease
  
• Diffuse cerebral dysfunction, e.g.
  
  
  
  • Encephalopathy
    
  • Haemorrhage
    
  • Hydrocephalus
    
  • Inflammation
    
  • Oedema
    
  • Space-occupying lesion
    
  • Trauma
  
  
• Fibrocartilaginous embolism
  
• Glossopharyngeal neuralgia
  
• Lower motor neurone disorders
  
  
  
  • Endocrine neuropathies, e.g.
    
    
    
    • Diabetes mellitus*
      
    • Hyperadrenocorticism
      
    • Hypothyroidism* (D)
    
    
  • Lumbosacral disease
    
  • Paraneoplastic neuropathies, e.g.
    
    
    
    • Insulinoma
    
    
  • Peripheral nerve neoplasia
    
  • Polyneuropathy, e. g.
    
    
    
    • Polyradiculoneuropathy
  
  
• Micturition-related collapse
  
• Narcolepsy/cataplexy
  
• Neuromuscular junction disorders
  
  
  
  • Botulism
    
  • Myasthenia gravis
  
  
• Seizures q.v.
  
• Swallowing-related collapse
  
• Upper motor neurone disorders
  
  
  
  • Central vestibular disease
    
  • Cerebellar disease
    
  • Cerebral disease
    
  • Peripheral vestibular disease
    
  • Spinal disease

Skeletal/joint disorders

• Bilateral cranial cruciate disease
  
• Bilateral hip disease
  
• Discospondylitis
  
• Intervertebral disc disease
  
• Multiple myeloma
  
• Osteoarthritis
  
• Panosteitis
  
• Patellar luxation
  
• Polyarthritis

Cardiovascular diseases

• Bradyarrhythmias q.v., e.g.
  
  
  
  • High-grade second-degree heart block
    
  • Sick sinus syndrome (D)
    
  • Third-degree heart block
  
  
• Congestive heart failure*
  
• Hypertension* q.v.
  
• Hypotension* q.v.
  
• Pericardial effusion* q.v.
  
• Tachyarrhythmias q.v., e.g.
  
• Ventricular tachycardia*
  
  
  
  • Supraventricular tachycardia

Drugs/toxins

• Alphachloralose
  
• Anticoagulant rodenticides
  
• Anticonvulsants
  
• Antihistamines
  
• Blue-green algae
  
• Cannabis
  
• Diclofenac sodium
  
• Glucocorticoids
  
• Hypotensive agents, e.g.
  
  
  
  • Beta blockers
    
  • Vasodilators
  
  
• Ibuprofen
  
• Insulin overdosage
  
• Iron salts
  
• Mistletoe
  
• Opioids
  
• Organophosphates
  
• Petroleum distillates
  
• Phenoxy acid herbicides
  
• Pyrethrin/pyrethroids
  
• Rhododendron
  
• Salbutamol
  
• Sedatives

Endocrine diseases

• Diabetes mellitus*
  
• Hyperadrenocorticism
  
• Hyperparathyroidism
  
• Hypoadrenocorticism (D)
  
• Hypoparathyroidism
  
• Hypothyroidism* (D)
  
• Insulinoma

Haematological diseases

• Anaemia* q.v.
  
• Hyperviscosity syndrome, e.g. polycythaemia

Inflammatory/Immune-mediated diseases

• Chronic inflammatory conditions*
  
• Immune-mediated haemolytic anaemia* q.v.
  
• Immune-mediated polyarthritis

Infectious diseases*

• Bacterial
  
• Viral
  
• Fungal
  
• Rickettsial
  
• Protozoal and other parasitic diseases

Infectious/inflammatory disease

Neurological/neuromuscular disease

• Cricopharyngeal achalasia
  
• Myasthenia gravis
  
• Myopathy, e.g.
  
  
  
  • Masticatory myopathy
  
  
• Trigeminal nerve disease, e.g.
  
  
  
  • Intracranial disease
    
  • Trigeminal neuritis

Obstruction

• Foreign body*
  
• Granuloma
  
• Neoplasia
  
• Sialocoele

Temporomandibular joint disease

Trauma*

• Fracture
  
• Haematoma
  
• Laceration