Spinal deformity in a sandtiger shark, Carcharias taurus Rafinesque: a clinical–pathological study

Abstract

The present study investigated spinal deformity in a captive sandtiger shark and describes the clinical and histopathological features of the lesion. Clinically, the shark presented a marked spinal curvature in the region between the pectoral girdle and cranial dorsal fin. Radiographic studies revealed scoliosis and kyphosis of the vertebral column with a modification of the basic structure of five vertebrae. Post-mortem examination confirmed the results of radiographic studies and histological examination showed remodelling and cartilaginous proliferation of the vertebral bodies together with necrosis, haemorrhage and signs of a local chronic inflammatory response extending to the surrounding muscle. Different aetiologies are proposed and discussed but nutritional imbalance (dietary vitamin deficiency) and/or traumatic injury are considered the most likely contributing factors.

Spinal deformities in a wild line of Poecilia wingei bred in captivity: report of cases and review of the literature

“…The most important are vitamin C [1,[42][43][44][45] , aminoacidic (tryptophan) [45] and phosphorous [46,47] deficiencies. On the contrary, excess of vitamin A is known to induce skeletal abnormalities in fish and such vitamin A-induced lesions also represent a popular model for studying the development of skeleton in fish larvae [48] .…”

“…However, vitamin C enriched high quality foods were used to feed fish in our study in order to avoid the occurrence of vitamin C deficiency. At the same time, such deficiency also causes decrease in collagen content preventing the formation of physiologically normal cartilage [44] , as well as jaw, snout and operculum deformities associated with distortion of gill filaments in young, rapidly growing fish [45] .…”

“…Other causes inducing vertebral deformity in fish are represented by the absence of a functional swim bladder [49] , as well as by traumatic injuries, which may occur during capture and/or transport [44] . Traumas may also be related to a strong water current [12] .…”

Mechanical properties of sand tiger sharkCarcharias taurusvertebrae in relation to spinal deformity

“…Many of these animals are eventually euthanized because of the gradual deterioration of their condition, thereby increasing pressure on wild stocks for exhibit specimens despite dwindling wild populations (Anderson et al, 2012). Hoenig and Walsh (Hoenig and Walsh, 1983), Berzins et al (Berzins et al, 1998;Berzins et al, 2002) and Preziosi et al (Preziosi et al, 2006) were the first to describe these spinal deformities, along with a variety of other skeletal tissue abnormalities including curled pectoral fins, gingival hyperplasia and permanently protruded upper jaws. A typical shark spine is composed of spool-shaped vertebral centra with concave ends, aligned end-to-end and separated by symmetrical intervertebral discs.…”

“…Microscopically, the injured tissues were characterized by the accumulation of granulocytes characteristic of an immune response and disorganized proliferation of hypertrophied chondrocytes indicative of ineffective healing; lack of remodeling may be a general characteristic of chondrichthyan cartilage, as is the case with mature articular cartilage in osteichthyan vertebrates (Ashhurst, 2004;Hall, 2005). Behaviorally, the affected sharks exhibited irregular swimming patterns and loss of forward thrust, and often sank to the bottom of their habitat (Hoenig and Walsh, 1983;Berzins et al, 1998;Berzins et al, 2002;Preziosi et al, 2006).…”