Page 1947 - Cote clinical veterinary advisor dogs and cats 4th

973.e2 Thymic Hemorrhage

Thymic Hemorrhage
VetBooks.ir Possible Complications

DIAGNOSIS
BASIC INFORMATION
Complications of treatment or the primary
Definition Diagnostic Overview disease have not been described for animals
Accumulation of blood in the parenchyma of The initial key to the diagnosis of thymic that survive.
the thymus hemorrhage is having suspicion for the disorder
in young animals with unexplained anemia and Recommended Monitoring
Synonym respiratory distress. • Clinical signs
Thymic hematoma • Packed cell volume (PCV), total protein
Differential Diagnosis • PT, aPTT, particularly as vitamin K 1 therapy
Epidemiology • Other causes of hemothorax: is discontinued
SPECIES, AGE, SEX ○ Trauma
• An uncommon disease that occurs primarily ○ Anticoagulant rodenticide toxicosis PROGNOSIS & OUTCOME
in dogs; rare cases in cats have been reported. ○ Intrathoracic neoplasia
• Thymic hemorrhage has been described • Other causes of hemopericardium: • Most reported cases have been associated with
predominantly in dogs < 2 years of age, ○ Heart base tumors fatal outcomes, possibly because of the low
although it has been seen in older dogs. ○ Right atrial hemangiosarcoma clinical suspicion of the disease and delay
○ Pericarditis in diagnosis and treatment.
GENETICS, BREED PREDISPOSITION • Occult blood loss into other sites such • Provision of timely, intensive supportive care
No sex or breed predispositions have been as the gastrointestinal (GI) and urinary in the form of fluids and blood products, and
identified, but in some reports, German tracts administration of vitamin K 1 for animals with
shepherds have been overrepresented. known or suspected rodenticide toxicosis
Initial Database have been associated with survival of some
RISK FACTORS • CBC: anemia; thrombocytopenia has been affected animals.
Potential risk factors that have been identified: described in some animals.
• Thoracic trauma or cervical stretching • Serum biochemical profile: hypoproteinemia PEARLS & CONSIDERATIONS
• Exposure to anticoagulant rodenticides (hypoalbuminemia and hypoglobulinemia)
• Thymic neoplasia (uncommon) • Thoracic radiographs/ultrasound: pleural Comments
effusion or a mediastinum widened by a • Perform thoracic radiographs for young
ASSOCIATED DISORDERS soft-tissue density (hemorrhage) animals with an acute onset of respiratory
• Hemothorax distress and anemia of undetermined origin.
• Hemomediastinum Advanced or Confirmatory Testing Consider the diagnosis if there is evidence of
• Hemopericardium (with heart base thymic • Thoracocentesis and fluid analysis can a mass or density in the mediastinum or if
remnants) confirm hemothorax. the animal has pleural effusion (hemothorax).
• Prolongations of one-step prothrombin time • When hemorrhage is documented or
Clinical Presentation (PT) and activated partial thromboplastin suspected in the absence of a history of
HISTORY, CHIEF COMPLAINT time (aPTT) are expected for animals with trauma, assess coagulation parameters to
• Acute onset of lethargy, depression anticoagulant rodenticide toxicosis. These rule out coagulation disorders.
• Tachypnea, respiratory distress animals may also have increases in serum
• Increased respiratory effort levels of proteins induced by vitamin K Technician Tips
• Sudden death absence or antagonism (protein induced by It may be difficult to place an IV catheter in
vitamin K antagonist [PIVKA]); toxicologic patients with severe hemodynamic collapse.
PHYSICAL EXAM FINDINGS analysis could reveal high concentrations An intraosseous catheter (proximal humerus,
• Mucous membrane pallor of specific rodenticides identified in blood proximal femur) is a viable substitute for initial
• Tachycardia samples or stomach contents. fluid or blood component therapy.
• Tachypnea • Cardiac ultrasound can rule out or document
• Muffled heart sounds and decreased lung the presence of heart base masses/tumors and Client Education
sounds ventrally are possible. pericardial effusion (hemopericardium). Avoid trauma and exposure to rodenticides.
• Jugular vein distention, jugular pulses, or
pulsus paradoxus if hemopericardium TREATMENT SUGGESTED READING
• Pain with compression of the cranial thorax Coolman BR, et al: Severe idiopathic thymic hem-
• Evidence of hemorrhage at other sites would Treatment Overview orrhage in two littermate dogs. J Am Vet Assoc
be possible with coagulopathy Treatment goals are to identify an underlying 205:1152, 1994.
cause when possible and provide hemodynamic
Etiology and Pathophysiology support. ADDITIONAL SUGGESTED
• Intrathymic bleeding secondary to thymic READINGS
trauma or a coagulation disorder, such Acute General Treatment Liggett AD, et al: Thymic hematoma in juvenile dogs
as vitamin K rodenticide toxicosis, is the • IV fluids (crystalloids, colloids) associated with anticoagulant rodenticide toxicosis.
proximate cause identified in some cases. • Blood products (whole blood, packed red J Vet Diagn Invest 14:416, 2002.
• Another proposed mechanism is bleeding blood cells [RBCs], plasma) Van der Linde-Sipman JS, et al: Hematomas in the
from increased vessel fragility associated with • Pericardiocentesis if in cardiac tamponade thymus in dogs. Vet Pathol 24:59, 1987.
normal thymic involution. • Vitamin K 1 for animals with historical or AUTHOR: Rance K. Sellon, DVM, PhD, DACVIM
• The initiating cause may not be identified laboratory features suggestive of anticoagu- EDITOR: Megan Grobman, DVM, MS, DACVIM
in some animals. lant rodenticide toxicosis

www.ExpertConsult.com