Bone marrow mastocytosis in dogs with myelosuppressive monocytic ehrlichiosis (Ehrlichia canis): a retrospective study.
BACKGROUND
Bone marrow mastocytosis has been reported rarely in naturally occurring canine monocytic ehrlichiosis (CME).


OBJECTIVE
The aims of the present study were to estimate the prevalence and magnitude of bone marrow mastocytosis in a case series of dogs with natural CME and to assess the association, if any, between mastocytosis and the clinical severity of the disease.


METHODS
Seventy-six dogs with confirmed CME (Ehrlichia canis) were included in the study. Affected dogs were allocated into group A (n = 51) without bone marrow hypoplasia and group B (n = 25) with bone marrow hypoplasia. Twenty clinically healthy Beagles not previously exposed to E canis served as controls (group C). The main inclusion criteria for group A were documentation of normocellular to hypercellular bone marrow and complete clinical cure following a 4-week treatment with doxycycline, while those for group B were bone marrow hypoplasia and lack of response to doxycycline. Bone marrow aspirate smears from all 96 dogs were Giemsa-stained and examined for the presence of mast cells, which were calculated as a percentage of 1,000 nucleated cells (NCs). The prevalence of mastocytosis was compared among the 3 groups by the Pearson's chi-square test.


RESULTS
Bone marrow mastocytosis (>0.1% of NCs) was found in 5 (20%) dogs in group B (range, 0.5-2.5% of NCs; median, 1% of NCs). One dog in each of groups A and C had 0.1% mast cells in the marrow. The prevalence of bone marrow mastocytosis in dogs in group B was significantly higher (P = .004) than in groups A and C.


CONCLUSIONS
Bone marrow mastocytosis can be seen in a substantial number of dogs with E canis-induced myelosuppression.
Mylonakis
Mathios E
ME
Clinic of Companion Animal Medicine, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece. mmmylonak@vet.auth.gr
Koutinas
Alex F
AF
Leontides
Leonidas S
LS
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001772:Blood Cell Count / Q000662:veterinary; D001854:Bone Marrow Cells; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003937:Diagnosis, Differential; D004283:Dog Diseases / Q000188:drug therapy / Q000453:epidemiology* / Q000473:pathology; D004285:Dogs; D004318:Doxycycline / Q000627:therapeutic use; D041061:Ehrlichia canis / Q000187:drug effects / Q000302:isolation & purification; D016873:Ehrlichiosis / Q000150:complications / Q000188:drug therapy / Q000453:epidemiology / Q000662:veterinary*; D005260:Female; D008297:Male; D008415:Mastocytosis / Q000453:epidemiology / Q000209:etiology / Q000473:pathology / Q000662:veterinary*; D015995:Prevalence; D012189:Retrospective Studies; D012720:Severity of Illness Index; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D004318:Doxycycline