Dog, Peripheral blood: Chronic lymphocytic leukaemia (CLL)

The blood smear identifies large numbers of lymphoid cells. 

These are approximately one to at maximum two times the diameter of an erythrocyte. 

They have scant pale basophilic cytoplasm and round to irregular nuclei with dense chromatin. 

Nucleoli are not observed.

Blast cells in acute lymphoblastic leukaemia (ALL) are larger and have prominent nucleoli and clumped chromatin.

Chronic lymphocytic leukaemia (CLL) in dogs is a disease characterised by an abnormal proliferation of clonal lymphoid cells in the bone marrow.

The leukaemic cells resemble mature lymphocytes morphologically and migrate throughout the blood and tissues.

The clinical signs of CLL are vague and include inactivity, lethargy, pyrexia, polyuria/polydipsia, inappetence, sporadic vomiting, weight loss and peripheral lymphadenopathy.

Lymphocytosis is commonly seen on laboratory analysis and hepatosplenomegaly, anaemia, thrombocytopenia and monoclonal gammopathy are occasionally observed.  

Cytoreductive chemotherapy has been performed in dogs with symptomatic CLL using chlorambucil or, occasionally, drugs for intensive lymphoma chemotherapy in veterinary medicine (MacEwen and others 1977, Hodgkins and others 1980, Leifer and Matus 1985, 1986, Couto and Sousa 1986).

Melphalan and prednisolone therapy also may achieve remission with few side effects in dogs with CLL.

First published: Wed, Oct 27 2010

Fujino, Y., Sawamura, S., Kurakawa, N., Hisasue, M., Masuda, K., Ohno, K. and Tsujimoto, H. (2004), Treatment of chronic lymphocytic leukaemia in three dogs with melphalan and prednisolone. Journal of Small Animal Practice, 45: 298-303.