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Aquatic Mammals 1997, 23.1, 59–68

Skin disorders in bottlenose dolphins (Tursiops truncatus), resident in the Sado estuary, Portugal
Stefan Harzen and Barbara J. Brunnick
Blue Dolphin Research and Consulting, P.O. Box 9243, Jupiter, FL 33458, USA

Abstract Throughout two periods, in 1986/87 and 1992/93, a systematic study was conducted of a group of bottlenose dolphins inhabiting the Sadoestuary. At the end of the second study period, 85% of the long term residents showed signs of skin disorders. Forty percent of these animals show signs of the skin disorder for 6 or more years. Skin samples were not collected or analysed to date, therefore, it has been impossible to determine the cause of the skin disorders. Comparison with observations in other areas suggest that habitatdegradation may play an important role when dolphins become sick and/or entire communities decline and eventually disappear. The appearance of skin disorders may indicate depressed or overworked immune systems that would normally counteract the disease. Such immune system deficiencies may be caused by stress, habitat degradation or contamination with pollutants. Introduction In recent years, it has becomeincreasingly obvious that environmental pollution and viral disorders play a role as cetacean pathogens. While much has been written about skin diseases in captive animals, reports from the wild are still scarce. Greenwood et al. (1974) described a variety of skin diseases in wild cetaceans, and Geraci et al. (1979) provided a detailed report on pox infection in wild animals. Circular marks havebeen observed in many cetaceans (Greenwood et al., 1974). These marks have been attributed to parasites and infections. In captivity, there appears to be a correlation between pox-like lesions and stress, environmental conditions, and the overall general health of the animal (Greenwood et al., 1974; Geraci et al., 1979). Other possible causes include temperature variations (Haebler & Moeller,1993) and immunosuppressive pollutants. Recently, autoimmune viruses, such as Moribillivirus, have been considered potential
 1997 EAAM

threats to dolphins as well (Lipscomb & Kennedy, 1994). Baker (1992), who examined 81 specimens from nine cetacean species in British waters, including the bottlenose dolphin, found several cutaneous abnormalities in about two third of this mixed sample ofcetaceans, including wounds or other traumatic injuries, viral infections and scars. Tattoo lesions on the skin were described, indicating a pox virus infection. These lesions are reported to be oval in shape, 0.5 to 7.0 cm long and usually orientated along the long axis of the body. They were characterised on pigmented skin by a black or grey outer line 1–3 mm wide, which was either uniform or composedof a series of spots. Inside the black line the skin was paler than the surrounding normal tissue and in the centre of larger lesions there were frequently linear longitudinal ulcers. Geraci et al. (1979) provided a similar description and correlated it to stress and poor health. Similar lesions have been observed in other areas and other species, such as the spotted dolphin (Stenella frontalis)in the Bahamas (Herzing, pers. comm.). Baker also found skin conditions that he interpreted as a herpes infection. This infection was characterised by oval shaped areas up to 6 cm long, that were paler in pigmented areas than the surrounding normal skin. Many of the animals studied were in good condition when they died, and ‘except where skin disease was extensive, there was no evidence to suggestill-health in the affected animals’ (Baker, 1992). A herpes virus infection was also described for dusky dolphins (Lagenorhynchus obscurus) from Peru (Van Bressem et al., in press). Reports on bacterial dermatitis are rare, supporting the findings of Dunn (1990), that most bacterial skin diseases are secondary, following primary viral, parasitic or traumatic insults. Rowntree et al. (1994)...
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