Retinal dysplasia in wild otters (Lutra lutra)

Eyes from 88 otters found dead in south-west England between 1990 and 2000, were collected as part of a larger pathological study. Histopathological examination of 131 eyes revealed dysplastic changes such as rosetting and folding in the retinas of 26 of the otters. In the eyes of 42 of the otters there were postmortem and fixation-induced retinal detachment which complicated the differentiation of dysplastic from normal retina, but 11 eyes had folds which probably indicated a dysplastic pathology. The eyes of 18 of the otters had inflammatory or autolytic changes which precluded a definitive evaluation of their dysplastic status. Liver samples from 55 of the otters were analysed for a range of polychlorinated hydrocarbons and for vitamin A. The otters with dysplastic retinas had significantly lower concentrations of vitamin A and higher concentrations of dieldrin than the otters with normal retinas.     

Cryptosporidium and Giardia in wild otters (Lutra lutra)

A total of 437 faecal samples from wild otter (Lutra lutra) were collected from 161 sites in Galicia (northwest Spain) and were analysed by a direct immunofluorescence antibody test (IFAT). Cryptosporidium sp. oocysts and Giardia sp. cysts were detected in 17 (3.9%) and 30 (6.8%) samples, respectively. The results demonstrate that otters may contribute to the contamination of watercourses, although further studies are required to establish which species or genotypes of Cryptosporidium and Giardia infect these animals and also the significance in terms of public health.     

Patterns and significance of bite wounds in Eurasian otters (Lutra lutra) in southern and south-west England

Postmortem examinations were carried out on 379 otters found dead in southern and south-west England between 1988 and 2003. Most (81 per cent) were road casualties, but many had open bite wounds and in some cases these had proved fatal. Mortality was strongly seasonal and was positively correlated with night length. Although numbers decreased in the summer months, the prevalence of bite wounds in adults was highest in late summer. The number of otters examined annually and the prevalence of bite wounds increased markedly during the study period, and in 2003 more than half the otters of both sexes had recent bite wounds. The majority of the bites were considered to have been caused by other otters, but some were thought to have been inflicted by American mink (Mustela vison). Bites to cubs were mostly caused by domestic dogs. The overall mortality due to bite wounds was approximately 10 per cent.     

Fatal adiaspiromycosis in a wild Eurasian otter (Lutra lutra)

Postmortem examination of an immature otter which died in the wild showed that large areas of the lungs were swollen and firm, with emphysema and haemorrhage in the remaining areas. Histopathological examination revealed large numbers of fungal adiaspores and an unusually severe inflammatory response. It was considered that respiratory impairment was the primary cause of the otter's death.     

Pathological changes and organochlorine residues in tissues of wild otters (Lutra lutra)

In 1984 two adult, wild otters (Lutra lutra) from north Norfolk were subjected to full post mortem examinations. One was found dead and the other sick. Both were thin. No evidence of infectious disease was found, but there were organochlorine concentrations of 433 and 75 mg/kg of fat (69 per cent polychlorinated biphenyls in both) in skeletal muscle. Leiomyoma of the reproductive tract and adrenocortical hyperplasia in one otter were similar to age associated changes in other mammals. Integumentary, including pedal, lesions were present in both otters. The possibility that the pedal lesions were caused by the toxic effects of polychlorinated biphenyls is discussed.     

Hepatocellular adenoma in a Eurasian otter (Lutra lutra)

A 7-year-old female Eurasian otter (Lutra lutra) at the Seoul Grand Park, Korea, died after displaying depression, anorexia, weight loss and rough skin for several days. At necropsy, a solitary friable round mass, which was approximately 12 × 9 × 5 cm and mottled dark red and yellow, was found bulging from the right hepatic lobe. Microscopically, the nonencapsulated, poorly circumscribed mass was composed of solid sheets of neoplastic hepatocytes. In addition, numerous small tan foci, ranging from 0.5 to 1.0 cm in diameter, were evenly scattered throughout the pancreatic tissue. These foci were found to be nonencapsulated, well-demarcated hyperplastic nodules of the exocrine pancreatic gland. We observed neither intrahepatic nor extrahepatic metastases. Based on the gross and microscopic changes, we diagnosed the animal as having a hepatocellular adenoma accompanied by exocrine pancreatic nodular hyperplasia.     

Tyzzer's disease in a Eurasian otter (Lutra lutra) in Scotland

A Eurasian otter (Lutra lutra) cub found in weak condition on the Isle of Harris, Scotland, developed bilateral corneal oedema 16 days after being admitted to a rehabilitation centre. It died unexpectedly on day 26. On postmortem examination, there was excess clear fluid in the body cavities and the liver was swollen with numerous pale focal lesions and petechial haemorrhages throughout. Histopathological examination revealed bundles of bacilli morphologically typical of Clostridium piliforme within hepatocytes. Comparative analysis of the nucleotide base sequence of a 16S rdna fragment amplified from the infected liver tissue revealed that it was identical to a C piliforme 16S rdna sequence. The possibility of concurrent infection with canine adenovirus type 1 was considered but none of the characteristic histopathological lesions was observed and examination of the liver by transmission electron microscopy was negative for virus particles. This appears to be the first record of Tyzzer's disease in an otter and the first in a wild animal in Britain.     

Malignant melanoma in a Eurasian otter (Lutra lutra).

An 11-yr-old female Eurasian otter (Lutra lutra) presented with multiple cutaneous nodules identified histologically as malignant melanomas of spindle cell and epithelioid cell type. Metastases were detected in lymph nodes and liver, and the tumor, which was derived from melanocytes, showed aggressive biological behavior. Only occasional reports exist of neoplastic disease in otters.     

Suspected Aleutian disease in a wild otter (Lutra lutra)

Clinical and pathological observations of a naturally occurring disease in a British wild otter (Lutra lutra) are reported. Systemic lymphoreticular proliferative changes with plasmacytosis, glomerulonephritis, arteritis and biliary hyperplasia closely resembled the pathological changes in Aleutian disease of mink (Mustela vison). Feral mink provided a possible source of infection.     

Canine adenovirus type 1 infection of a Eurasian river otter (Lutra lutra)

A 10-year-old female Eurasian river otter (Lutra lutra) died after prolonged anorexia and weight loss in the Seoul Grand Park Zoo, Seoul, Republic of Korea. On necropsy, the liver was found to be swollen and friable with 1 lobe enlarged and necrotic. The other organs showed no significant alterations except for mild atrophy of the right kidney. Microscopically, there was multifocal hepatic necrosis. The hepatocytes around the necrotic areas were swollen and contained large basophilic intranuclear inclusions. Periportal infiltration by plasma cells and lymphocytes was also evident. Transmission electron microscopy revealed characteristic hexagonal virus particles sized approximately 70 nm in diameter in the nuclei of the hepatocytes, which were consistent with an adenovirus. Polymerase chain reaction of the formalin-fixed, paraffin-embedded liver sections was used to determine whether the virus was either the canine adenovirus type 1 (CAV-1), canine adenovirus type 2 (CAV-2), or some other viral agent. The results of these tests showed that the virus was CAV-1. To our knowledge, this is the first report on a CAV-1 infection in an otter.     

Cholecystitis in otters (Lutra lutra) and mink (Mustela vison) caused by the fluke Pseudamphistomum truncatum

Between 1988 and 2004, postmortem examinations were carried out on 445 otters found dead, mostly as a result of road traffic accidents, in southern and south-west England. Thickened, shrunken gall bladders were observed in 10 cases, the first in 2000 and the others between February 2002 and August 2004. A digenean fluke, Pseudamphistomum truncatum, was found in the gall bladders of three cases and also in three of seven American mink examined. Nine of the 10 otters and all the mink came from a localised area of Somerset, indicating that the fluke has become established in the local fish population. P. truncatum has not been recorded previously in Britain, and the results suggest that it has been introduced recently, possibly in imported fish.     

Eurasian otter (Lutra lutra), a definitive host for Dirofilaria immitis.

A mature male and a mature female Dirofilaria immitis were found in the right ventricle of the heart of a naturally infected 2-yr-old male Eurasian otter (Lutra lutra) that had died of severe lung congestion at a zoo in South Korea. Both developing embryos and microfilariae were present in the uterus of the female D. immitis. Although circulating microfilariae were not detected in blood or tissue, the Eurasian otter may serve as a definitive host for D. immitis.     

Three neoplasms in a Eurasian otter (Lutra lutra): malignant melanoma,trichoblastoma and mammary gland adenoma

An eighteen-year-old female Eurasian otter became emaciated and died. Necropsy examination revealed nose and thoracic cutaneous masses, abdominal subcutaneous mass, and multiple nodules in the liver and lungs. Malignant melanoma was found in the nose cutaneous mass and to have metastasized to the liver, lungs, kidneys, adrenal glands, mammary glands and left mandibular lymph node. The neoplastic cells were labeled for vimentin, melanoma, and S100. The cutaneous mass in the thoracic area consisted of spindle shaped neoplastic epithelial cells and was diagnosed as trichoblastoma. Mammary gland adenoma was observed in the abdominal subcutaneous mass. This is the first report of primary three neoplasms of malignant melanoma, trichoblastoma and mammary gland adenoma in a Eurasian otter.     

Reintroduction of the Eurasian otter (Lutra lutra) in northeastern Spain: trapping, handling, and medical management.

In 1993 a reintroduction project for the Eurasian otter (Lutra lutra) was initiated in northeastern Spain (Girona, Catalonia) to restore extirpated populations. Between 1996 and 2000, 43 otters were captured from southwestern and northern Spain and from Portugal with modified foot-hold traps and transported to Barcelona Zoo. Lesions produced by capture were classified into four categories of increasing severity. Thirty four (79%) animals had category I, three (7%) had category II, five (12%) had category III, and only one (2%) had category IV injuries. During captivity five (11%) animals died, including one from a precapture problem. Radiotransmitter devices were implanted i.p. into 36 otters to monitor postrelease movement and survival. At least three radio-implanted otters have bred successfully in Girona province, Catalonia, after release in that area.     

Polymerized bovine hemoglobin (Oxyglobin Solution) administration in two river otters (Lutra canadensis)

Polymerized bovine hemoglobin (Oxyglobin Solution^®) was successfully administered to two river otters (Lutra canadensis) that required general anesthesia and surgery for trap‐related injuries. In both animals, blood oxygen content was maintained at presurgical levels despite a 47–70% decrease in their hematocrit. Otter 1 received a dose of 19 mL kg^?1, given at a rate of 29 mL kg^?1 h^?1. Otter 2 received a dose of 20 mL kg^?1, given at a rate of 5 mL kg^?1 h^?1. For many of the uncommon species, there are limited resources in the form of blood products to treat anemia, blood loss or hypovolemia. Successful use of polymerized bovine hemoglobin in these two otters suggests that it is useful for acute treatment of anemia and blood loss in such species.     

Pulmonary silicosis in three North American river otters (Lutra canadensis).

Three adult female North American river otters (Lutra canadensis) demonstrated severe anesthetic complications shortly after being immobilized for dental procedures. Two of the animals died shortly after anesthesia, and the third otter died 2 mo after immobilization. All three animals were diagnosed with pulmonary silicosis on the basis of histopathology, polarized light microscopy, and mass spectrometry. One animal also had primary pulmonary bronchoalveolar carcinoma. Significant concurrent disease was not found in other organs. Analysis of the lung tissue by laser microbe mass spectrometry confirmed the presence of an aluminum silicate in the lung tissue associated with insulation material used in nest box construction.     

Technique of mandibular salivary gland biopsy in river otters (Lutra canadensis).

A Franklin-Silverman biopsy needle was used to obtain 2-5- x 1-2-mm mandibular salivary gland tissue samples percutaneously from nine North American river otters (Lutra canadensis). The samples were suitable for fluorescent antibody or polymerase chain reaction rabies testing. Ninety-two percent (11/12) of the biopsy procedures yielded histologically confirmed salivary gland tissue, and the remaining biopsy yielded adipose tissue. No complications were noted after 5-21 days.     

Glucosuria associated with renal calculi in Asian small-clawed otters

Urine from one female and 2 male Asian small-clawed otters (Aonyx cinerea) with bilateral renal calculi, one female with unilateral calculi, and one nonaffected male were evaluated for abnormal urinary crystalloid excretion. One otter with bilateral renal calculi had cystic calculi composed of calcium oxalate monohydrate and dihydrate. The 2 affected males were littermates, as were the 2 affected females, but the 2 litters were from different parents. At the time of the study, the otters did not have clinical signs of disease. Hematologic and serum biochemical, electrolyte, and enzyme values were normal. The urinary excretion of calcium, oxalate, uric acid, phosphate, citrate, and amino acids in otters with renal calculi was similar to that of the nonaffected otter. The 4 otters with renal calculi had glucosuria but the nonaffected otter did not have glucosuria. The glucosuria, in the absence of hyperglycemia, suggested a renal tubular transport defect for glucose. Other renal abnormalities were not found.