Water temperature fluctuations as a key driver of cetacean pox (tattoo) lesions in bottlenose dolphins Tursiops truncatus

Abstract

Dolphin tattoo lesions are superficial non-raised skin lesions caused by poxviruses. Their presentation can vary but typical lesions in bottlenose dolphins are circular to ovoid with concentric rings of black stippling. These lesions have at times been suggested as an indicator of overall dolphin health and welfare. This study explored the effect of water temperature on the extent of tattoo lesions in 25 dolphins, along with established hematological health parameters and food consumption. Study animals consisted of 9 males and 16 females with dolphin tattoo lesions ranging in age from 2 to 45 yr. A significant decrease (p < 0.01) in extent and appearance of tattoo lesions was documented following increase in water temperature from 21-24°C (70-75°F) to 25.5-26.5°C (78-80°F). Reduction in tattoo lesions could be noted as early as 2-3 wk following water temperature increase. Marked reduction to complete resolution of tattoo lesions was reproducibly seen 5-6 wk post temperature increase. Food consumption following temperature increase was variable: decrease in intake was noted in 48% of dolphins, increase in intake in 52%. Routine blood parameters (complete blood count, serum chemistry panel, fibrinogen, erythrocyte sedimentation rate) remained within normal limits. A significant increase (p < 0.05) in extent and appearance of tattoo lesions was documented in 3 dolphins as early as 4-5 wk following a decrease in water temperature from 26.1°C (79°F) to 21°C (70°F). Water temperature is a key environmental parameter affecting cetacean pox (‘tattoo’) lesions in bottlenose dolphins. The absence of changes in hematological parameters along with lack of correlation between extent of pox lesions and food intake indicates that dolphin tattoo lesions are not an appropriate indicator of overall health.