Multicentric neurofibromatosis with rectal prolapse in a California sea lion (Zalophus californianus)

An approximately 31-yr-old California sea lion (Zalophus californianus) with a history of chronic visual impairment and corneal disease presented with slow onset, progressive neurologic deficits. Treatment for rear flipper paresis was not effective and the animal was euthanatized. Histopathologic findings included hepatocellular and biliary neoplasia, ocular amyloidosis, adrenal adenoma and pheochromocytoma, and spinal cord changes consistent with multicentric neurofibromatosis. This is the first documentation of these conditions in a California sea lion.     

Secondary amyloidosis and renal failure in a captive California sea lion (Zalophus californianus)

A 16-yr-old, captive-born, female California sea lion (Zalophus californianus) was evaluated for intermittent lethargy, partial anorexia, and polydipsia of 2 wk duration. The animal was immobilized for physical examination. It was in thin body condition, with multifocal mucosal ulcerations over the caudal and ventral tongue. Blood was collected for hematology, serum chemistry, and leptospirosis serology. Serum chemistry revealed severe azotemia, mild hyperglycemia, and severe hyperphosphatemia. The animal went into cardiac arrest during recovery from anesthesia and died. On histopathology, abundant amorphous, finely fibrillar, eosinophilic material was deposited in the kidneys, and smaller amounts of the same material were found in the splenic and pancreatic vessels; these findings are consistent with systemic secondary amyloidosis. The animal also had chronic nephritis, which, coupled with renal amyloidosis, resulted in renal failure and death. Systemic amyloidosis should be considered as an additional differential diagnosis for renal failure in California sea lions.     

Endocarditis associated with Escherichia coli in a sea lion (Zalophus californianus).

Endocarditis associated with Escherichia coli was diagnosed in a 2-year-old male California sea lion (Zalophus californianus). The diagnosis was based on light microscopic examination and bacterial isolation from the valvular lesion. This is the first case of bacterial endocarditis reported in a sea lion.     

Lingual squamous cell carcinoma in a California sea lion (Zalophus californianus).

A 28-yr-old female California sea lion (Zalophus californianus) in a commercial aquarium developed an ulcerated lingual tumor and died. Necropsy revealed a moderately differentiated squamous cell carcinoma. Immunohistochemical staining and electron microscopic studies revealed that the tumor cells were strongly positive with anti-keratin-cytokeratin antibody and had abundant tonofibrils and desmosomes. The neoplasm had metastasized to a mandibular lymph node.     

Systemic mycosis in a California sea lion (Zalophus californianus) with detection of cystofilobasidiales DNA

A 6-yr-old, intact male California sea lion (Zalophus californianus) with a systemic mycosis died after 5 wk of antifungal drug therapy. Antemortem clinical findings included hind flipper swelling, ring-lesions on skin of the flippers, and dermal nodules that increased in size and number spreading from the hind flippers and ventral abdomen to the foreflippers and muzzle. Lesions were accompanied by severe lymphadenopathy and development of systemic clinical signs despite therapy using itraconazole and later voriconazole. Histopathologic evaluation of biopsies revealed granulomatous dermatitis due to infection by fungus-producing yeast cells in tissue. Isolation attempts, using biopsied skin and tissue samples collected at necropsy, failed to yield growth of a fungus producing yeast cells like those in histologic section. Consensus polymerase chain reaction (PCR) tests of biopsied skin for fungal DNA produced an amplicon having significant sequence identity with a Cystofilobasidiales, a fungus belonging to a subclade that includes several Cryptococcus spp. Histopathologic evaluation of necropsy tissues revealed a systemic mycosis with yeast cells disseminated throughout subcutis, lymph nodes, and viscera. Hepatic necrosis was identified associated with acute liver failure, possibly from the voriconazole administration. This is the first report documenting the clinical presentation, treatment, and pathologic findings of infection associated with Cystofilobasidiales in a marine mammal and serves to expand the understanding of mycoses in pinnipeds.     

Surgical resection of an orbital fat prolapse in a California sea lion (Zalophus californianus)

A 23-year-old captive female California sea lion (Zalophus californianus) developed an inferiotemporal subconjunctival swelling of the right eye. Surgical excision of the mass was performed and a diagnosis of orbital fat prolapse was confirmed histopathologically. There was no recurrence of orbital fat prolapse at 15 months post operatively. This is the first known case of orbital fat prolapse in the California sea lion.     

Urate nephrolithiasis in a northern elephant seal (Mirounga angustirostris) and a California sea lion (Zalophus californianus).

Nephrolithiasis has rarely been reported in marine mammals. During 2004 and 2005, two cases of nephrolithiasis were diagnosed during routine necropsy examination, one in a northern elephant seal (Mirounga angustirostris) and one in a California sea lion (Zalophus californianus). Nephroliths were found throughout both kidneys during necropsy examination, varying in size from 1-10 mm in diameter in the northern elephant seal and from 1-15 mm in diameter in the California sea lion. Necropsy and histopathology revealed nephroliths in association with renal pelvic dilation and pyelonephritis in both animals. In addition, hydronephrosis was noted in the sea lion. Nephroliths were composed of uric acid and ammonium urate in the northern elephant seal and of ammonium urate in the California sea lion. The underlying disease leading to nephrolith formation was not determined; however, it is hypothesized that unknown metabolic derangements due to morphologic or physiologic differences may have played a role. This is the first report of urate nephrolithiasis in the California sea lion and northern elephant seal.     

Domoic acid toxicity in Californian sea lions (Zalophus californianus): clinical signs, treatment and survival

Eighty-one Californian sea lions (Zalophus californianus) with signs of domoic acid toxicity stranded along the coast of California in 1998 when there were blooms of the domoic acid-producing alga Pseudonitzschia australis off-shore. In 2000, a further 184 sea lions stranded with similar clinical signs, but the strandings occurred both during detectable algal blooms and after the blooms had subsided. The clinical signs in these 265 Californian sea lions included seizures, ataxia, head weaving, decreased responsiveness to stimuli and scratching behaviour. Affected animals had high haematocrits, and eosinophil counts, and high activities of serum creatine kinase. They were treated supportively by using fluid therapy, diazepam, lorazepam and phenobarbitone. Fifty-five of the 81 sea lions (68 per cent) affected in 1998 and 81 of the 184 (44 per cent) affected in 2000 died despite the treatment. Three of the 23 sea lions which survived in 1998 were tracked with satellite and radiotransmitters; they travelled as far south as San Miguel Island, California, and survived for at least three months. Eleven of the 129 animals which were released stranded within four months of being released.     

Aerobic bacterial flora of the nasal cavity in Gulf of California sea lion (Zalophus californianus) pups

Nasal swab samples from clinically healthy California sea lions pups (Zalophus californianus) from six different reproductive rookeries in the Gulf of California were collected to determine the type and frequency of the representative aerobic bacterial microflora of their nasal mucosa. A total of 114 samples were examined and 100 bacterial isolates were identified and typified by microbiological and biochemical standard tests. Fifty four isolates corresponded to Gram positive bacteria (54%) and 46 isolates to Gram negative bacteria (46%). Fifteen bacterial genera were identified, including Micrococcus, Arcanobacterium, Corynebacterium, Moraxella, Neisseria, Escherichia, Kurthia, Acinetobacter, Staphylococcus, Brevibacillus, Bacillus, Klebsiella, Stenotrophomonas, Pseudomonas and Aeromonas. The most frequently isolated genera were Moraxella (24%), Micrococcus (18%), and Corynebacterium (15%). These results show the presence in the nasal cavity of sea lions of several microorganisms. Although considered part of the normal microflora, they may also be opportunistic pathogens for their hosts and may act as a potential natural sentinel of environmental changes.     

Use of laser rhinoscopy to treat a nasal obstruction in a captive California sea lion (Zalophus californianus).

Laser rhinoscopy was used to treat a nasal obstruction in a captive California sea lion (Zalophus californianus). The rehabilitated, adult, female sea lion developed mucopurulent, intermittent, bilateral nasal discharge and functional nasal obstruction 20 mo after acquisition by the Aquarium of the Pacific in Long Beach, California. A 3-mm-thick soft tissue structure spanning the region between the soft and hard palates, a deviated nasal septum, and several nasopharyngeal polyps were identified. Biopsies and cultures of the obstructive web showed ulcerative granulation tissue with suppurative inflammation, bacterial infection, and a partial section of an arthropod larva (not speciated). Laser rhinoscopy was performed to relieve the caudal nasopharyngeal obstruction and ablate the polyps. The sea lion appeared to breathe through the nares with lessened nasal discharge for a period of 6 wk after laser therapy, but within 8 wk the mucopurulent nasal discharge returned, the obstruction had reformed, and the sea lion was euthanized. Postmortem examination confirmed antemortem diagnoses of caudal nasopharyngeal obstruction secondary to inflammatory tissue; however, no additional sections of arthropod parasites were located microscopically.     

Immobilisation of free-ranging Galapagos sea lions (Zalophus californianus wollebaeki)

Nine free-ranging Galápagos sea lions were immobilised for marking, using a combination of ketamine (3 to 5 mg per kg) and xylazine (0.5 to 1.0 mg per kg). The degree of effect depended largely on the animals' behavioural and physiological state before immobilisation (after parturition, high arousal, subject to aggression, etc.) All nine animals survived. Overheating in the immobilised state may quickly result in heart and circulatory failures.     

Isoflurane anaesthesia in four sea lions (Otaria byronia and Zalophus californianus)

OBJECTIVE: To (1) evaluate a purpose-built chamber for inducing isoflurane anaesthesia in sea lions and (2) assess isoflurane as an anaesthetic for dental surgery in these species. STUDY DESIGN: Prospective case study. ANIMALS: Four sea lions, aged between 5 and 12 years and weighing 74-110 kg, with dental disease. METHODS: Sea lions were restrained in a custom-built acrylic chamber into which 5% isoflurane (vapourizer setting) was delivered in O(2) (30 L minute(-1)) from three anaesthetic machines. When the animals were recumbent, the chamber was opened and induction completed using a face mask. Anaesthesia was maintained with 1.5-3.0% isoflurane (vapourizer setting) for 10-15 minutes and after tracheal intubation, was maintained with 1.0-3.0% isoflurane (end-tidal) for 41-255 minutes, using a partial rebreathing system with CO(2) absorption. RESULTS: During induction, the sea lions attempted to support their weight on their thoracic limbs before slipping into sternal or lateral recumbency. Sea lions underwent either root canal surgery, 'crowning' or canine tooth extraction. The animals were completely unresponsive during these operations and apnoea was never encountered at any point during anaesthesia. After surgery, the sea lions were placed into transport cages and their tracheae extubated once they began to move their heads. Thereafter, recovery from anaesthesia was smooth and no signs of distress were observed. Animals were able to raise their forequarters using their flippers within 1 hour of the operation and were returned to the aquarium about 2 hours after surgery. CONCLUSIONS AND CLINICAL RELEVANCE: The purpose-built induction chamber is safe for inducing isoflurane anaesthesia in spontaneously breathing sea lions and isoflurane is an effective anaesthetic in this species.     

Pathology of domoic acid toxicity in California sea lions (Zalophus californianus)

Over 100 free-ranging adult California sea lions (Zalophus californianus) and one Northern fur seal (Callorhinus ursinus), predominantly adult females, were intoxicated by domoic acid (DA) during three harmful algal blooms between 1998 and 2000 in central and northern California coastal waters. The vector prey item was Northern anchovy (Engraulis mordax) and the primary DA-producing algal diatom was Psuedonitzschia australis. Postmortem examination revealed gross and histologic findings that were distinctive and aided in diagnosis. A total of 109 sea lions were examined, dying between 1 day and 10 months after admission to a marine mammal rehabilitation center. Persistent seizures with obtundation were the main clinical findings. Frequent gross findings in animals dying acutely consisted of piriform lobe malacia, myocardial pallor, bronchopneumonia, and complications related to pregnancy. Gross findings in animals dying months after intoxication included bilateral hippocampal atrophy. Histologic observations implicated limbic system seizure injury consistent with excitotoxin exposure. Peracutely, there was microvesicular hydropic degeneration within the neuropil of the hippocampus, amygdala, pyriform lobe, and other limbic structures. Acutely, there was ischemic neuronal necrosis, particularly apparent in the granular cells of the dentate gyrus and the pyramidal cells within the hippocampus cornu ammonis (CA) sectors CA4, CA3, and CA1. Dentate granular cell necrosis has not been reported in human or experimental animal DA toxicity and may be unique to sea lions. Chronically, there was gliosis, mild nonsuppurative inflammation, and loss of laminar organization in affected areas.     

Disseminated blastomycosis in two California sea lions (Zalophus californianus).

Two captive California sea lions (Zalophus californianus) from different facilities were diagnosed with disseminated blastomycosis. The first, a 12-yr-old male, died after a 3-wk history of progressive anorexia and lethargy. Gross examination revealed acute jejunitis with focal perforation and associated peritonitis, along with severe purulent bronchopneumonia. The second, a 15-yr-old female, was euthanized after a 2-wk history of severe cutaneous ulceration and declining clinical condition. Gross examination revealed severe pyogranulomatous bronchopneumonia and ulcerative dermatitis. Histopathologic examination in both individuals revealed severe multifocal subacute to chronic pyogranulomatous pneumonia associated with massive numbers of fungal organisms morphologically compatible with Blastomyces sp. Fungal organisms were 8-20-microm-diameter broad-based budding yeasts with thick, refractile, double-contoured walls. The male sea lion had multifocal transmural Blastomyces-induced enteritis with subsequent rupture and peritonitis. The organism was also present in the liver, with minimal associated inflammation. The female had severe multifocal pyogranulomatous ulcerative dermatitis associated with large numbers of intralesional fungal organisms. Dissemination to the spleen had occurred in both animals. A serologic immunodiffusion test for Blastomyces dermatitidis was positive in the male. The presumptive primary pathogen in both cases was Blastomyces dermatitidis.     

Characterization of a novel papillomavirus species (ZcPV1) from two California sea lions (Zalophus californianus)

A seven-year old California sea lion (Zalophus californianus) presented with focally extensive, bilaterally symmetric, proliferative axillary skin lesions and preputial lesions. A second California sea lion in the same population presented with similar proliferative lesions on the underside of the tail. Histopathology revealed epidermal hyperplasia with severe hyperkeratosis, with proliferating keratinocytes forming broad, branching pegs that extended into the dermis. Pan-papillomaviral consensus PCR was used to obtain initial E1 sequence template and the complete genome was determined using a combination of rolling circle amplification and specific-primer PCR. Analysis revealed a novel papillomavirus, Zalophus californianus papillomavirus 1 (ZcPV1), with seven open reading frames encoding five early proteins (E6, E7, E1, E2 and E4) and two late proteins (L1 and L2). Phylogenetic analysis revealed that (ZcPV1) is most closely related to Equine papillomavirus 1 (EcPV1) in the genus Zetapapillomavirus, and Canine papillomaviruses 3 and 4 (CPV3, CPV4) in the genus Chipapillomavirus. The lesions regressed without intervention over a period of several months.