A 3 Year old male Australian fur seal Arctocephalus pusillus doriferus) was examined at a local oceanarium because of the trainer's complaint that the animal was lethargic and had diarrhea of several days duration. The seal had eaten 7kg of fish and accomplished all normal show behaviors 4 hours prior to being examined. The seal presented as being 5% dehydrated, had muddy mucous membranes, and yellow pasty feces were evident around the anal opening. The temperature was 36.8C.. Inspiratory dyspnea was evident and breathing was 10/minute. Intravenous catheterization was unsuccessful but blood was obtained for a CBC and blood chemistry. Oxygen was given by face mask. Within 40 minutes of the original presentation the seal went into grand mal seizures and died. The seal was necropsied shortly post mortem.

Eight days later a 5 year old male Australian sea lion (Neophoca cinerea) was examined at the same oceanarium for foul smelling diarrhea, lethargy and reduced food intake. On examination the animal was eating normally. Mucous membrane color was good. CRT was <2 seconds. The temperature was 38.2. Rales were detectable on inspiration. Blood was drawn for CBC and blood chemistry.

Based on the results of a bacterial culture and sensitivity done on the fur seal's feces growing Edwardsiella sp., ampicillin was instituted at the rate of 22mg/kg twice daily in fish.

The CBC revealed monocytosis and neutrophilia with some autolysis. Total bilirubin and CPK were elevated. The animal continued to do well on antibiotic therapy and was feeding normally. An occasional cough was noted by the trainer. The animal died acutely 2 days later with signs of hemoptysis before it could be examined.

Necropsy Results-Fur Seal

Lesions found in the fur seal were as follows: The liver was characterized by multiple pinpoint to 5mm necrotic white foci through all lobes. The stomach contained fragments of the plastic pool surround. There was minor edema of the intestinal wall and the mesenteric lymph nodes were enlarged and edematous. The etiologic diagnosis was septicemia with the causative organism unknown.

Necropsy Results-Sea Lion

Gross lesions found in the sea lion included a large amount of blood in the nose and mouth originating from the lungs. The heart was congested with prominent vasculature and petechial hemorrhages were noted in the epicardium and endocardium. The pleural cavity contained approximately 3 liters of sanguinous fluid with a protein content of 48g/l. The stomach contained rocks, metallic fragments and hard plastic. No evidence of gastric ulceration was seen.

Histology-Fur Seal

The liver was characterized by multiple foci of necrosis and neutrophil infiltration. No specific etiologic agents were seen to be associated with these lesions. The lamina propria of the small intestine was hypercellular and infiltrated with a mixture of neutrophils and mononuclear cells. The mesenteric lymph nodes were edematous and accumulations of macrophages and neutrophils were seen in the medullary sinuses. Central follicular lymphoid depletion was also noted.

The spleen was characterized by multiple foci of necrosis and multifocal abscesses.

The lungs contained an accumulation of proteinaceous fluid and severe vascular congestion.

Histology-Sea Lion

The heart showed multifocal hemorrhage and mild interstitial edema. Sections of the spleen displayed widespread areas of necrosis and hemorrhage of the lymphoid follicles. The lung showed severe inflammation that varied from lobule to lobule. Many lobules showed areas of marked edema and necrosis. Sections of the small intestine exhibited mild necrosis of the lumen with the lamina propria being infiltrated by lymphocytes and neutrophils.

Microbiology

Swabs were taken from various organs of the fur seal at necropsy and cultured. E. coli and Proteus sp. were found in the liver and colon of the fur seal. Pseudomonas sp. was isolated from the liver.

Fecal culture from the sea lion grew E.coli, Aeromonas sp., Campylobacter sp., and Edwardsiella sp., all sensitive to ampicillin. At necropsy Pseudomonas pseudomallei was obtained in large numbers from lung and spleen.

Follow up culture of the Pseudomonas sp. obtained from the seal proved to be Pseudomonas pseudomallei as well.

Discussion

Pseudomonas pseudomallei, the etiologic agent causing melioidosis has been reported from most mammalian species. Being a soil saprophyte, natural infection can occur through inhalation, ingestion or wound penetration. (Weber et al, 1969). Evidence exists for infection by aspiration of contaminated water as well. (Achane et al, 1985, Vedros, Personal communication, 1992).

A thorough search for the organism in the environment (sea water, pool water, feed fish, and pool surround) proved negative. Both cases occurred just after a period of major flooding which brought a large amount of suspended soil sediment and water of decreased salinity to the animal's pool. Decreased salinity decreases the bacteriacidal effect of sea water against Pseudomonas pseudomallei . (Liong et al, 1985).

The disease presented in both the enteric and pulmonic forms. It is theorized that the enteric septicemia in the seal was secondary to the sharp piece of plastic found in its stomach causing an entry portal. The portal of entry for the sea lion seems to have been either due to aspiration of the bacteria off the water surface or aspirated with the water.

References

1.  Achana,V., Silpapojakul, K., Thininta, W., Kalanowakul, S.,(1985). Acute Pseudomonas pseudomallei pneumonia and septicemia following aspiration of contaminated water: a case report. SE Asian J. Trop. Med. Pub. HIth 16: 500-504.

2.  Liong, E., Vedros, N.A., Hammond, D.D. (1985). Pseudomonas pseudomallei infection in a dolphin (Tursiops gilli): a case report. Aquat. Mamm. 1: 20-22.

3.  Weber, D.R. , Douglas, L.E., Brundage, W.G., Stallkamp,T.C. (1969). Acute varieties of melioidosis occurring in US soldiers in Vietnam Am. J. Med. 46: 234-21993_04344.