Proliferation capacity of T-lymphocytes is affected transiently after a long-term weight gain in Beagle dogs

Across species obesity is associated with several disorders but in companion animals little information is available on the impact of chronic obesity on immune competence. The aim of the present study was to investigate whether weight gain and stable obese bodyweight affects the immune cell response. Obesity was induced in eight adult healthy beagle dogs (weight gain group; WGG) by a weight gain period (WGP) of 47 weeks, which was immediately followed by a period (stable period: SP) of stable obesity of 26 weeks. Eight adult healthy beagle dogs were included as a control group (CG) and remained at their ideal bodyweight throughout the entire study. Body composition was measured at five intervening time-points. Concentration of serum leptin and inflammatory cytokines, functionality of lymphocytes and phagocytic activity of neutrophils and monocytes were evaluated at ten intervening time-points. Serum leptin concentration was rising during the WGP in the WGG but went to lower concentrations during the SP. At the end of long-term weight gain, a decreased mitogen-induced proliferation of T-lymphocytes was noted but this alteration seemed to be transient after stabilization of bodyweight. This finding may imply an altered immune response for dogs with different energy balances. However, no systemic low grade inflammation or alteration in other immune cell functions was observed. Consequently it is suggested that the change in energy balance during the onset of obesity (becoming obese versus being obese), evokes an additional obesity-related disorder in dogs, i.e. impaired T-lymphocyte immune function.