Muscle Pathology in Free-Ranging Stranded Cetaceans

Abstract

Despite the profound impact that skeletal muscle disorders may pose for the daily activities of wild terrestrial and marine mammals, such conditions have been rarely described in cetaceans. In this study, the authors aimed to determine the nature and prevalence of skeletal muscle lesions in small and large odontocetes and mysticetes ( n = 153) from 19 different species. A macroscopic evaluation of the epaxial muscle mass and a histologic examination of the longissimus dorsi muscle were performed in all cases. The only macroscopically evident change was variable degrees of atrophy of the epaxial muscles ( longissimus dorsi, multifidus, spinalis) in emaciated specimens. The histopathological study revealed single or combined morphological changes in 91.5% of the cases. These changes included the following: degenerative lesions (75.2%), muscle atrophy (37.9%), chronic myopathic changes (25.5%), parasitic infestation (9.2%), and myositis (1.9%). The skeletal muscle is easily sampled during a necropsy and provides essential microscopic information that reflects both local and systemic conditions. Thus, skeletal muscle should be systematically sampled, processed, and examined in all stranded cetaceans.

Retrospective Study of Traumatic Intra-Interspecific Interactions in Stranded Cetaceans, Canary Islands

“…These findings have been previously reported in association with stressful agonal events or in severely polytraumatized animals. For example: segmental myodegeneration and contraction band necrosis have been described before in traumatized stranded cetaceans (7); pigmentary tubulonephrosis, as well as hyaline casts, have been associated with capture myopathy in live strandings (47); and the presence of vacuoles, known as hyaline globules, in the hepatocytes and myocardiocytes have been previously reported in acute stressful deaths (4,41,48,49). Thus, histological determination of agonal changes (in skeletal and cardiac muscle, kidneys, lungs, liver, and adrenal glands) can support gross evidence in cases suspected of traumatic intra-interspecific interaction.…”

“…Severe changes were observed also in the longissimus dorsi, with multifocal polyphasic myocyte degeneration and necrosis: segmental myonecrosis associated with the stress stranding syndrome, atrophy due to emaciation, and myositis due to the shark bites (7). The other cases were two Risso's dolphins (cases 17 and 20) with decompression sickness (44).…”

“…A false killer whale (case 14) presented an intralesional stingray spine in the tongue causing severe chronic perforating glossitis and stomatitis (4). This animal also presented with severe muscular atrophy due to starvation, muscular degenerative changes due to an active stranding, and antemortem shark bites (7). Fatal interactions between dolphins and stingrays have been welldocumented.…”

“…Other lesions that had been reported in fatal encounters include: blunt traumas with subcutaneous focal or multifocal extensive hemorrhages, hematomas, tearing of the blubber, vertebral and/or ribs fractures, myonecrosis, tearing of the parietal pleura with associated-pulmonary hemorrhages, hemothorax, retroperitoneal hemorrhages, perforation of the abdominal wall, and liver rupture (3)(4)(5)(6). Histologically, acute monophasic degeneration and hemorrhages in the muscle are common findings (4,7). Pulmonary fat emboli (8) and myo-/hemoglobinuric nephrosis (4) can be observed by specific staining.…”

Stress cardiomyopathy in stranded cetaceans: a histological, histochemical and immunohistochemical study

“…These different pathological entities have acute stress as the central aetiopathogenesis, potentially leading to the death of the animal or seriously aggravating a previous disease situation. These issues impact the subsequent rehabilitation of animals, reducing the effectiveness of therapy and limiting successful recovery 39 40 42 44–49…”