Hepatic Lesions in Cetaceans Stranded in the Canary Islands

Abstract

Abstract. This article describes the gross, histopathologic, and ultrastructural findings of the livers of cetaceans stranded on the coast of the Canary Islands between 1992 and 2000. A total of 135 cetaceans were included in the study, among which 25 were common dolphins (Delphinus delphis), 23 Atlantic spotted dolphins (Stenella frontalis), 19 striped dolphins (Stenella coeruleoalba), and 15 other species of dolphins and whales. The most common lesion observed in these animals was a nonspecific chronic reactive hepatitis (47/135), followed by hyaline intracytoplasmic inclusions in hepatocytes (33/135). Parasitic cholangitis was detected in 8/135 animals, whereas hepatic lipidosis was presented in 7/135 animals. The ultrastructure of hyaline hepatocytic cytoplasmic inclusions is described, and possible causes of these inclusions are discussed.Key words: Cetaceans; dolphins; hepatic lesions; liver; ultrastructure.Information on cetaceans found stranded on the coast of the Canary Islands has been collected by the Histology and Pathology Unit of Las Palmas of Gran Canaria University during an 8-year period (1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000). One hundred and thirty-five cetacean strandings occurred on the shores of these islands, involving both single and multiple strandings of adults and juvenile cetaceans, but to date there have been no surveys of the causes of illness in the wild, free-living dolphin and whales found dead in the Canary Islands.In the study of the stranded cetaceans, the liver, as in other studies, 2,12,13 was extensively analyzed and a variety of lesions that merited further investigation were found. Chronic liver disease of unknown cause is a common ailment in dolphins and is clinically characterized by wasting but is rarely characterized by jaundice. Hepatic lesions consist of hepatocyte degeneration, fatty change, and fibrosis. 33 Chronic liver disease is generally regarded as being nutritional in origin, but there is no definite evidence to support this. 19,33 Different types of acute hepatitis associated with nutritional or environmental toxins and biologic agents, such as viruses, bacteria, fungi, and parasites, have also been reported in stranded dolphins. 30 Parasitic infections have been recognized amongst the pathologic changes found in marine mammals. 34 Campula spp. is a common trematode that primarily inhabits the bile and pancreatic ducts, stomach, and intestine of cetaceans. 36 Affected ducts are dilated, fibrosed, and infiltrated with mononuclear cells, and the epithelium is hyperplastic. 8,27 Dolphins, as other cetaceans, are at the top of the marine food chain, and they accumulate pollutants in their tissues during their life. Therefore, this species is an excellent bioindicator to evaluate contamination of the marine environment. Numerous studies have been carried out to analyze concentrations of pollutants in dolphins from different areas of the world. 1,[4][5][6]16 Despite some studies that have described hepatic lesions in stranded dolphins, 2,9,12,22,29...

Cetacea

“…Stranded animals suffering from starvation or that are nursing calves that have a dietary intake high in carbohydrates accumulate excessive triglycerides in hepatocytes. Hepatic lipidosis in very young animals is considered physiologic (Jaber et al, 2004). In these cases, the liver is diffusely pale tan and waxy.…”

Renal Lesions in Cetaceans from Brazil

“…Because of their reniculate morphology and increased medullary thickness, the kidneys play a key role in salt excretion and water conservation (Hedges et al, 1979). In cetaceans and other marine mammals, pathological changes have been described in the lung (Gonzales-Viera et al, 2011;Venn-Watson et al, 2012), liver (Jaber et al, 2004), thyroid gland (Cowan and Tajima, 2006) and pituitary gland (Cowan et al, 2008), but there has been no specific study of renal pathology in these species.…”

Non-specific reactive hepatitis in dolphins stranded in the Canary Islands

“…Hepatitis has been commonly found in wild and captive dolphins (Baker 1992;Di Guardo et al 1995;Kirkwood et al 1997;Cornaglia et al 2000;Jaber et al 2004). Chronic liver disease of unknown cause is a common ailment in dolphins.…”

“…In all these previous studies, both non-purulent and interstitial hepatitis and subacute to chronic pericholangitis were the most commonly found forms of hepatitis. However, a few instances of non-specific reactive hepatitis (NSRH) have been reported in cetaceans (Jaber et al 2004).…”