P. Sullivan et al., ALTERED PLATELET INDEXES IN DOGS WITH HYPOTHYROIDISM AND CATS WITH HYPERTHYROIDISM, American journal of veterinary research, 54(12), 1993, pp. 2004-2009
Changes in platelet indices (platelet count and platelet size) and PCV
associated with thyroid disease were studied in 7 dogs with hypothyro
idism and 21 cats with hyperthyroidism that were admitted to the veter
inary teaching hospital. Compared with control (euthyroid) dogs, dogs
with hypothyroidism had higher platelet count (P = 0.003), smaller pla
telet size (P = 0.01), and lower PCV (P = 0.02). Comparison of the gro
up of hyperthyroid cats with a group of similarly aged, clinically nor
mal cats with normal thyroxine values indicated that the group of hype
rthyroid cats had significantly (P = 0.03) higher mean platelet size t
han did control cats, but differences were not found in mean platelet
count or PCV. Results of this investigation indicate that the changes
in platelet size reported in human beings with thyroid endocrinopathie
s also are found in animals so-affected. Although the pathogenesis of
platelet abnormalities in animals with thyroid derangement is unclear
and likely is multifactorial, the observed relation between platelet a
nd erythrocyte production in this group of dogs is consistent with rep
orts of an inverse relation between thrombocytopoiesis and erythropoie
sis in iatrogenically hyperthyroid mice and in mice exposed to hypoxia
.