A preliminary overview of skin and skeletal diseases and traumata in small cetaceans from South American waters

VAN BRESSEM, VAN WAEREBEEK, REYES, FÉLIX, ECHEGARAY, SICILIANO, BENEDITTO, FLACH, VIDDI, AVILA, HERRERA, TOBÓN, BOLAÑOS, MORENO, OTT, CASTINEIRA, MONTES, CRESPO, FLORES, HAASE, MENDONÇA, LAETA, FRAGOSO

THE LATIN AMERICAN JOURNAL OF AQUATIC MAMMALS

LAJAM

Lugar: Rio de Janeiro; Año: 2007 vol. 6 p. 7 - 42

1676-7497

We succinctly review and document new cases of diseases of the skin and the skeletal system, and external traumata in cetaceans from Ecuador, Colombia, Peru, Chile, Argentina, Uruguay, Brazil, and Venezuela. The survey revealed 587 cases diagnosed with a significant pathology, injury or malformation on a total of 7,635 specimens of 12 odontocete species examined or observed in 1984-2007. Tattoo skin disease (TSD), lobomycosis-like disease (LLD) and cutaneous diseases of unknown aetiology seem to be emerging in several populations. TSD was confirmed in eight species from the SE Pacific and SW Atlantic. LLD affected only coastal Tursiops truncatus but was found in four tropical countries, namely Colombia, Ecuador, Peru and Brazil. Lobomycosis was confirmed by histology in one male from the Tramandaí estuary, Brazil. All LLD affected specimens were encountered in the vicinity of major ports and cities and a possible association with chemical or organic water pollution was suspected. Whitish velvety cutaneous marks associated with scars occurred in coastal T. truncatus, Sotalia guianensis and a Pseudorca crassidens. Large, rounded lesions were seen in a calf Cephalorhynchus eutropia and one C. commersonii. Cutaneous wounds and scars as well as body traumata possibly related to net entanglements and boat collisions were observed in 71 dolphins and Burmeister?s porpoises. Traumatic injuries resulted in the partial or complete amputation or other disfiguring scars of appendages in 17 cases. Fractures of the skull, ribs and vertebrae thought to be caused by violent, fisheriesrelated interactions or boat collisions were seen in single individuals of Delphinus capensis, Lagenorhynchus obscurus, T. truncatus, S. guianensis and Ziphius cavirostris. Prevalence of osteopathology in small cetaceans from Peru, Brazil and Venezuela ranged widely, from 5.4% to 69.1%. In four species from Peru cranial lytic lesions were the most frequently observed disease (5.4%-42.9%), followed by hyperostosis and ankylosing spondylitis in, respectively, offshore (31%, N=42) and inshore (15.4%, N=26) T. truncatus. Fractures and other bone traumata were seen in 47.2% of 53 axial skeletons of S. guianensis from northern Rio de Janeiro State (Brazil) in 1987-1998. A high prevalence (48.4%, N=31) of, apparently congenital, malformations of cervical vertebrae observed in a 2001-2006 sample may be explained by a hypothetical genetic bottleneck in this population. Malformations with deficient ossification would clearly increase susceptibility to fractures. This study demonstrates the use of a continent-wide analysis to discern epizootiological trends more readily than any local study could provide. Secondly, it underscores the need for focussed research on the effects of human activities on the spread of diseases in cetaceans, particularly in near-shore populations that utilize highly degraded coastal habitats.Tursiops truncatus but was found in four tropical countries, namely Colombia, Ecuador, Peru and Brazil. Lobomycosis was confirmed by histology in one male from the Tramandaí estuary, Brazil. All LLD affected specimens were encountered in the vicinity of major ports and cities and a possible association with chemical or organic water pollution was suspected. Whitish velvety cutaneous marks associated with scars occurred in coastal T. truncatus, Sotalia guianensis and a Pseudorca crassidens. Large, rounded lesions were seen in a calf Cephalorhynchus eutropia and one C. commersonii. Cutaneous wounds and scars as well as body traumata possibly related to net entanglements and boat collisions were observed in 71 dolphins and Burmeister?s porpoises. Traumatic injuries resulted in the partial or complete amputation or other disfiguring scars of appendages in 17 cases. Fractures of the skull, ribs and vertebrae thought to be caused by violent, fisheriesrelated interactions or boat collisions were seen in single individuals of Delphinus capensis, Lagenorhynchus obscurus, T. truncatus, S. guianensis and Ziphius cavirostris. Prevalence of osteopathology in small cetaceans from Peru, Brazil and Venezuela ranged widely, from 5.4% to 69.1%. In four species from Peru cranial lytic lesions were the most frequently observed disease (5.4%-42.9%), followed by hyperostosis and ankylosing spondylitis in, respectively, offshore (31%, N=42) and inshore (15.4%, N=26) T. truncatus. Fractures and other bone traumata were seen in 47.2% of 53 axial skeletons of S. guianensis from northern Rio de Janeiro State (Brazil) in 1987-1998. A high prevalence (48.4%, N=31) of, apparently congenital, malformations of cervical vertebrae observed in a 2001-2006 sample may be explained by a hypothetical genetic bottleneck in this population. Malformations with deficient ossification would clearly increase susceptibility to fractures. This study demonstrates the use of a continent-wide analysis to discern epizootiological trends more readily than any local study could provide. Secondly, it underscores the need for focussed research on the effects of human activities on the spread of diseases in cetaceans, particularly in near-shore populations that utilize highly degraded coastal habitats.