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806 Polycythemia Vera

• Cats may have ultrasonic evidence of PKD ○ Stage I-II CKD: recheck every 3-6 months. Client Education
with a negative PKD1 genetic test. Consider a ○ Stage III CKD: recheck every 2-3 months. • Because most PKD is due to an autosomal
different mutation in the PKD1 or candidate
VetBooks.ir genes or other causes of renal cysts (e.g., • Urinalysis (with consideration for urine affected animal will have the mutant PKD1
dominant trait, 50% of offspring from an
○ Stage IV CKD: recheck monthly.
neoplasia, age-related cysts).
protein/creatinine ratio) ± urine culture
gene. Screening (genetic or ultrasound) and
should be performed at least annually.
suggested in commonly affected breeds.
TREATMENT • Blood pressure measurement should be subsequent removal of positive animals is
performed at least q 3 months or 1 week • Kittens can be screened by ultrasound at <
Treatment Overview after antihypertensive drug dose adjustments. 16 weeks, but if negative, screening should
Affected animals should not be used for • Changes in clinical signs also warrant recheck. be repeated when the cat is at least > 10
breeding. Animals with clinical signs related months of age, or genetic testing should be
to PKD should be managed as other animals PROGNOSIS & OUTCOME performed.
with CKD. • Genetic screening can be completed in cats
• Not all cats with PKD develop azotemia. > 8 weeks old.
Acute General Treatment • PKD tends to progress more slowly than • If an individual cat with PKD is important
No treatment is specific for PKD; treat for many other types of CKD. After azotemia to a breeding program, breed only to PKD-
CKD and associated complications. Draining develops, long-term prognosis is poor. negative cats, and screen offspring. Assuming
the cysts does not provide any advantage and the affected parent is heterozygous for the
introduces the risk of bacterial contamination. PEARLS & CONSIDERATIONS mutant PKD1 gene, one-half of the offspring
will be affected and should be neutered; the
Chronic Treatment Comments unaffected individuals can be bred.
Same as for CKD (pp. 167 and 169) Although hypertension is common in people
with PKD, it occurs infrequently in healthy SUGGESTED READING
Possible Complications cats with PKD. Domanjko-Petric A, et al: Polycystic kidney disease: a
Cysts can become infected. Alkaline and review and occurrence in Slovenia with comparison
lipid-soluble antibiotics, including fluoroqui- Prevention between ultrasound and genetic testing. J Feline
nolones, clindamycin, chloramphenicol, and Eliminate affected animals from breeding Med Surg 10:115-119, 2008.
trimethoprim-sulfonamide, penetrate cysts well. population. AUTHORS: Catherine E. Langston, DVM, DACVIM;
Adam Eatroff, DVM, DACVIM
Recommended Monitoring Technician Tips EDITOR: Leah A. Cohn, DVM, PhD, DACVIM
• Routine recheck, including physical exam, Owners and breeders can collect and submit
weight, CBC (or packed cell volume), and samples for genetic testing at home. Technicians
serum biochemistry panel; frequency depends can help instruct clients on obtaining cheek
on disease severity swab samples.

Polycythemia Vera

Clinical Presentation
BASIC INFORMATION in the accumulation of morphologically and
HISTORY, CHIEF COMPLAINT functionally normal RBCs
Definition Mainly caused by or associated with ○ JAK2 gene mutation occurs in 90% of
An inappropriate, absolute increase in red blood hyperviscosity human polycythemia vera patients and has
cell (RBC) mass as measured by RBC count, • Neurologic changes (e.g., behavior, motor, been identified in a dog with polycythemia
hematocrit (HCT), and hemoglobin (Hb) or sensory), mental dullness, seizures vera.
concentration • Lethargy, exercise intolerance, collapse • Erythrocytosis may lead to the hyper-
• Hemorrhage (e.g., epistaxis, hyphema) viscosity syndrome and resultant clinical
Synonyms signs.
• Polycythemia rubra vera PHYSICAL EXAM FINDINGS
• Strictly speaking, primary erythrocytosis is None, one, or many may be present: DIAGNOSIS
the more accurate term for this disorder; • Hyperemic or cyanotic mucous membranes
however, even though polycythemia implies • Erythema of the skin Diagnostic Overview
increases in all circulating blood cell lines, • Polyuria and polydipsia (PU/PD) The goals are to determine whether a true
the term polycythemia vera is used more • Splenomegaly increase in red cell mass is present and then
commonly. rule out erythrocytosis secondary to increased
Etiology and Pathophysiology erythropoietin. Because polycythemia vera is
Epidemiology • Absolute primary erythrocytosis an autonomous increase in red cells, repeatable
SPECIES, AGE, SEX • Autonomous production of RBCs (erythro- elevations in HCT, RBC count, and Hb are
Usually middle-aged to older dogs or cats poietin independent) expected. Polycythemia vera is a diagnosis of
• Myeloproliferative clonal disease exclusion, and a complete diagnostic workup
ASSOCIATED DISORDERS • Arises from a multipotent hematopoietic is indicated to rule out all other possibilities
Hyperviscosity syndrome (p. 509) progenitor cell in the bone marrow, resulting in the differential diagnosis.

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