"Polycythemia Vera"
TUMOR TIDBITS  Volume 2; Number 7; May 1, 2001 
Editor: Kevin A. Hahn, DVM, PhD, Dipl - ACVIM (Oncology) & Overall Nice
Guy! 

POLYCYTHEMIA VERA

OVERVIEW:  Polycythemia vera is a myeloproliferative disorder.  A
disease of older dogs and cats.  

SIGNS:  Signs are gradual in onset and run a chronic course.  Signs
include depression, anorexia, weakness, high blood viscosity, polydipsia
and polyuria, erythema of skin and mucous membranes, dilated and
tortuous retinal blood vessels, splenomegaly and hepatomegaly uncommon.

DIFFERENTIAL DIAGNOSIS:  Severe dehydration; Renal neoplasia; Chronic
pyelonephritis; Hyperadrenocorticism; Androgen stimulation; Pulmonary
disease; Cardiac disease. 

DIAGNOSTIC FINDINGS:  Absolute increase in RBC mass; Leukocytosis in 50%
of dogs; Normal arterial PO2; Serum erythropoietin concentration is low
to zero.  Thoracic radiography, electrocardiography, cardiac
ultrasonography, abdominal radiography, renal ultrasonography, and
intravenous pyelography are recommended to determine underlying cause.
Cytologic examination of bone marrow and core biopsy may be diagnostic. 

TREATMENT RECOMMENDATIONS:   Phlebotomy and concurrent replacement with
isotonic fluids intravenously for quick relief of signs during clinical
crisis.  Hydroxyurea to inhibit intracellular DNA synthesis and retard
bone marrow proliferation (40 to 50mg/kg divided twice daily and titrate
to response and toxicity (dogs and cats).  Busulfan can be substituted
for hydroxyurea; also requires careful monitoring for myelosuppression.
Periodic recheck examinations including CBC and platelet count to
monitor toxic effects on bone marrow.

COMMENTS:  Rare disorder, rule out primary renal, adrenal,
cardiopulmonary disorders.  Prognosis guarded but patient care is
manageable with long-term chemotherapy.

Have More Questions?  Don't hesitate to call or email us at Gulf Coast
Veterinary Oncology!

Kevin

Kevin A. Hahn, DVM, PhD, Diplomate ACVIM (Oncology)
  & Overall Nice Guy
Gulf Coast Veterinary Oncology
1111 West Loop South, Suite 150
Houston, TX 77027
www.gcvs.com 
drhahn@gulfcoastvetspec.com