Abstract

An adult female California sea otter (Enhydra lutris) presented acutely anorectic, dyspneic and lethargic. A complete blood count revealed a pronounced neutrophilia, with a small percentage of immature polymorphonuclear cells. Antibiotics and analgesics were administered intramuscularly, but the animal was found dead approximately 12 hours after presentation. Gross necropsy findings included the presence of a swollen, erythematous epiglottis, nearly occluding the glottis; pharyngeal abscessation; pulmonary edema; and a yellow pea-sized gritty lesion at the distal margin of the right lung. Two similar, smaller lesions were present at the distal margin of the left lung. The uterus was dilated and a slightly mottled gray-red. A 6 mm in diameter cystic dilatation was present within the endometrium of the right uterine horn and the lumen contained a green-gray mucoid material. A primary histopathological diagnosis of suppurative, necrotizing severe pharyngitis with abscess formation was made. Significant secondary findings included a multifocal, granulomatous, subacute, moderate pneumonia; subacute to chronic, granulomatous bronchitis/bronchiolitis; pulmonary cryptococcosis; and chronic, mild endometritis.

Case History

A female California sea otter (Enhydra lutris), maintained at Sea World of California since 1978, presented lethargic and dyspneic at the time of her early morning feeding, after behaving normally the previous day. The otter was restrained, with little resistance, for venipuncture and the intramuscular administration of 750 mg of cephalothin (35.2 mg/kg) and 500 mg (23.5 mg/kg) of dipyrone, followed by 500 mg cephalexin (23.5 mg/kg) intramuscularly 8 hours later. A complete blood count revealed a pronounced neutrophilia, with a small percentage of immature polymorphonuclear cells. The otter ingested about I kg of clam meat 3 hours after the administration of medication and, possibly, small amounts thereafter, but was found dead in the early evening, 11 hours after her early morning feeding. At the time of death, the otter appeared in good flesh (wt. = 21.3 kg), with unmatted pelage.

At necropsy, the epiglottis was swollen, erythematous and nearly occluded the glottis. On cut-surface the epiglottis contained yellow, purulent material and a 3 mm in diameter abscess was present at the site of the right hyoid apparatus. The tracheal mucosa was damp and appeared congested. The small airways were filled with clear froth, a small amount extending into the bronchi. The lungs were atelectic and congested on cut surface. A yellow, pea-sized, mineralized lesion was present at the distal margin of the right lung and two similar, smaller lesions were present at the distal margin of the left lung.

The right ventricular epicardium was pale, the paleness extending approximately 1 mm into the myocardium. The heart appeared very rounded, but otherwise unremarkable.

A 5 mm in diameter, firm, fleshy erythematous area (possibly a corpora hemorrhagicum) was present on the right ovary. The uterus was dilated, containing green-gray mucoid material, and was a slightly mottled gray-red. A cystic dilatation, 6 mm in diameter, was present within the endometrium of the right uterine horn and a pea-sized, white polyp was present on the endometrial surface proximal to the dilatation.

The submandibular lymph nodes were firm and a large amount of dark pigment was apparent on cut-surface. The cervical and mediastinal lymph nodes were enlarged, nodular and a mottled red and yellow on cut-surface. The right thyroid measured 4 cm in length, while the left thyroid measured 2.5 cm in length.

The gross necropsy diagnosis was asphyxiation due to glottal obstruction from abscessation of the epiglottis and adjacent tissue. Secondary gross necropsy diagnoses included generalized lymphadenopathy, likely infectious in origin; cystic endometritis; and focal pulmonary granulomata of unknown origin.

Routine H and E histopathological examination revealed a marked infiltration of plasma cells, lymphocytes, and macrophages of fibrous muscular tissue adjacent to the epiglottis. Widespread inflammatory cells separated muscle, fibrous tissue and elastic fibers. A section of pharynx, lined with squamous epithelium and covering an abscess was covered with blisters containing fluid and cellular debris. The dermis and connective tissue underlying the pharyngeal epithelium was heavily infiltrated with lymphocytes, macrophages and neutrophils, in other areas. No etiological agents were apparent histologically.

The bronchi and bronchioles contained fluid and cellular debris and were surrounded by lymphocytes and macrophages. Alveoli were either collapsed, emphysematous or filled with macrophages or fluid and the alveolar capillaries were congested. The mass attached to the pulmonary pleura was composed of sheets of lymphoid cells intermingled with irregular areas of necrosis. Small, budding, encapsulated yeast organisms, comparable in size (10-12 μ) and shape with Cryptococcus neoformans were found within necrotic foci.

A moderate number of fibrous papillary projections were found on the surface of the epicardium. and a moderate number of nests of lymphoid cells were found under the epicardial epithelium. The pale area on the right ventricular epicardium was a layer of mature adipose tissue, approximately 0.5 to 1.5 mm on thickness. A few small nests of lymphoid cells were noted in the myocardium, but an active myocarditis was not apparent.

Endometrial glands, lined by tall endometrial epithelium were filled with inspissated, slightly eosinophilic material.

Lymphoid tissue was reactive, with a moderate amount of hemosiderin laden macrophages within the sinusoids. Medullary cords were filled with plasma cells.

The hepatic sinusoids were markedly congested. Multifocal areas of hepatocellular necrosis with secondary kupffer cell hyperplasia were found throughout the liver parenchyma, especially around the hepatic portal triads.

Thyroid follicles were markedly irregular in size and shape. Many follicles were cystic and contained a papillary hyperplasia of follicular epithelium whereas other follicles were composed of 5-6 hypertrophied follicular cells with little to no lumen. Thyroglobulin was absent in many follicles and a moderate amount of finely granular, yellow pigment was found in the cytoplasm of follicular epithelial cells.

Histopathological diagnoses included a severe, necrotizing cellulitis, pharyngitis, epiglottitis, with abscess formation; a moderate, subacute multifocal, granulomatous pneumonia, accompanied by a subacute to chronic, granulomatous bronchitis/bronchiolitis; a necrotic mass, composed of lymphoid cells and cellular debris attached to the pulmonary pleura containing yeast-like organisms compatible with Cryptococcus neoformans within necrotic foci. Additional diagnoses included: moderate diffuse cystic hyperplasia of the thyroid gland; chronic, mild endometritis with inspissation of the endometrial glands; a mild, multifocal hepatic necrosis with kupffer cell hyperplasia and; evidence of healed, moderate, chronic inflammation of the epicardium and myocardium.

The immediate cause of death in this otter was probably the acute pharyngeal edema and inflammation, exacerbated by the presence of pulmonary disease. The cause of the pharyngitis was probably secondary to some type of oral wound. Possible causes for the pharyngeal wound include sharp objects in the otter's diet such as chitinous sea urchin spines and shrimp exoskeletons.

The pulmonary lesions, including the bronchitis and multifocal granulomatous pneumonia, appeared to be due to Cryptococcus neoformans, which we do not believe has been previously reported in sea otters. The granulomatous pneumonia and bronchitis/bronchiolitis would likely have resulted in the otter's death had the otter not succumbed to the acute pharyngitis/epiglottitis.

Sea otters, like most non-domestic animals, are adept at masking signs of clinical illness. Depression of appetite and decreased grooming activity are often the first observations suggesting illness in sea otters. A rapid, fatal course of the pharyngitis/epiglottitis is suggested by the loss of appetite only on the day of death and the well-groomed, unmatted, pelage.

This is Sea World of California Technical Contribution No. 8911-C.

Products mentioned:

 Dypyrone, The Butler Company, 66215. Veterinary Laboratories, Inc., Lenexa, KA

 Keflin, Eli Lilly and Co., Indianapolis, IN 46285