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von Willebrand Disease 1043

Drug Interactions PEARLS & CONSIDERATIONS bodies of the mandible while the mouth is
Ranitidine can interfere with hepatic metabo- Comments open.
VetBooks.ir Possible Complications • Concentrating only on the GI tract too Technician Tips Diseases and Disorders
lism of other drugs.
Emphasize to the owners the need to strictly
early can lead to misdiagnosis and erroneous
treatment.
• Weight loss due to malnutrition
• Dehydration • Vomiting can be caused by IBD even if there follow nutrition guidelines.
• Hypokalemia is no history of diarrhea or any abnormalities SUGGESTED READING
• Sometimes, metabolic alkalosis with hypo- in the stomach. The small intestine should Gallagher A: Vomiting and regurgitation. In Ettinger
chloremia if a pyloric (sub) obstruction is always be biopsied during endoscopy. SJ, et al, editors: Textbook of veterinary internal
present • The area under the tongue must be examined medicine, ed 8, St. Louis, 2017, Elsevier, pp
for a linear foreign body in every vomiting 158-164.
PROGNOSIS & OUTCOME cat; this area is most easily visualized by AUTHOR: Sylvie Daminet, DVM, PhD, DACVIM,
pressing dorsally on the skin of the underside DECVIM
Depends on the cause (ventral surface) of the mandible between the EDITOR: Leah A. Cohn, DVM, PhD, DACVIM

von Willebrand Disease

BASIC INFORMATION Kerry blue terrier, Manchester terrier, ○ Abnormal bleeding from traumatic/
miniature pinscher, papillon, Pembroke surgical wounds
Definition Welsh corgi, poodle, schnauzer, and • Pallor from blood loss anemia
Hereditary primary hemostatic defect is caused sporadic cases in any breed
by a quantitative or functional deficiency of von ○ Type 2 VWD: German short-haired Etiology and Pathophysiology
Willebrand factor (VWF). VWF is an adhesive pointer, German wirehaired pointer • Distinct VWF mutations causative for type 3
protein required for normal platelet-collagen ○ Type 3 VWD: Chesapeake Bay retriever, VWD have been described in Scottish terriers
binding at sites of small vessel injury. Clinical Dutch kooiker, Scottish terrier, Shetland and Dutch kooiker dogs.
expression varies in severity from a mild bleed- sheepdog, and sporadic cases (recent • Homozygosity for a mutation located at
ing tendency after injury to more severe forms cases in Australian shepherd, border a splice site of the VWF gene has been
characterized by recurrent mucosal hemorrhage collie, cocker spaniel, Labrador retriever, associated with low VWF protein in type
and prolonged bleeding from normal processes, Maltese) 1 VWD.
such as deciduous tooth loss. • Types 2 and 3 VWD cause a moderate to
Clinical Presentation severe bleeding tendency.
Synonyms DISEASE FORMS/SUBTYPES • The clinical severity of type 1 VWD
Factor VIII–related antigen (old terminology; • Type 1 VWD: quantitative protein deficiency. generally correlates with decrease in VWF
protein is now referred to as von Willebrand Low plasma concentration of VWF (von concentration.
factor [VWF]), VWD Willebrand factor antigen [VWF:Ag]) with • VWF is an adhesive protein required for
proportionate reduction in VWF function; normal platelet-collagen binding and platelet
Epidemiology the VWF protein has a full distribution of aggregate formation at sites of small vessel
SPECIES, AGE, SEX multimeric forms. injury under high shear.
• von Willebrand disease (VWD) is the most • Type 2 VWD: quantitative and functional • A lack of VWF impairs platelet plug forma-
common hereditary bleeding disorder of protein deficiency; low plasma VWF:Ag level tion and causes bleeding despite normal
dogs. It is rare in cats. has a disproportionate decrease in VWF func- in vitro platelet numbers, normal platelet
• Severe forms typically manifest by 1 year of tion measured by collagen binding or support aggregation, and normal coagulation cascade
age, but milder forms may be inapparent of platelet agglutination. VWF protein lacks parameters (normal coagulation profile).
unless the patient undergoes surgery or the high-molecular-weight multimers.
trauma. • Type 3 VWD: severe VWF deficiency, DIAGNOSIS
undetectable plasma VWF (VWF:Ag
GENETICS, BREED PREDISPOSITION < 0.1%) Diagnostic Overview
• Autosomal trait with three type classifications: VWD typically causes signs of mucosal hemor-
○ Type 1 VWD: mild to moderate; recessive HISTORY, CHIEF COMPLAINT rhage and prolonged postoperative/traumatic
or incomplete dominant inheritance • Severe forms: recurrent mucosal bleeding, hemorrhage. Platelet count and coagulation
○ Types 2 and 3 VWD: severe; recessive prolonged bleeding from loss of deciduous screening tests are normal.
inheritance teeth or minor wounds, blood-loss anemia
• Males and females express and transmit after surgery or trauma Differential Diagnosis
VWD with equal frequency. • Mild forms: few spontaneous or severe bleeds; • Primary hemostatic defects
• In recessive forms, affected pups inherit a abnormal bleeding typically observed after ○ Thrombocytopenia
VWF mutation from both dam and sire. surgical or traumatic injury ○ Acquired or hereditary platelet dysfunc-
• Affected breeds tion, thrombocytopathias (e.g., patient
○ Type 1 VWD: Airedale, Akita, Bernese PHYSICAL EXAM FINDINGS taking aspirin)
mountain dog, dachshund, Doberman • Exam may be normal. • Coagulation factor deficiency
pinscher, German shepherd, golden • Abnormal hemorrhage • Vasculopathy or erosive/infiltrative vessel
retriever, greyhound, Irish wolfhound, ○ Mucosal bleeding defect causing mucosal hemorrhage

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