Introduction

On 20 July 1987 a male, juvenile Common Harbor Porpoise, Phoecoena phoecoena, was found stranded along the northern Oregon coast near Gearhart. The specimen weighed approximately 15.75 kg. It was found along with an adult of the same species that had already died. Three attempts to replace him to the ocean were met with failure by the local authorities. The juvenile was then taken to a local aquarium at Seaside for determination of disposition. The next day the porpoise--nicknamed "Wally"--was driven to Tacoma, Washington and the Point Defiance Zoo and Aquarium for further assessment.

Case History

Measurements on 20 July 1987 showed an overall length of 86 cm, with 3.2 cm snout to melon, 44 cm snout to dorsal fin, 11 cm snout to blowhole, 13 cm snout to eye, 17 cm snout to ear, 20 cm snout to anterior inside flipper, 38 an snout to umbilicus, 41 cm snout to edge of genital slit, and 64 an snout to anus. The flipper anterior inside tip was 16.5 cm, axilla to tip 10.2 cm, and a maximum width of 6.4 cm. The fluke width was 26 cm. The teeth were noted to just be erupting. The age of the specimen was estimated to be two weeks or less, based on the total length of the specimen and on the degree of healing of the umbilicus (personal communication, Bill Walker). Upon arrival at Point Defiance Zoo the porpoise was tube-fed a blended formula of 250 cc tap water, three small smelt (tails removed), and a small amount of STAT (a 50% fat, 20% carbohydrate, vitamin, mineral and electrolyte supplement from PRN Pharmacal, Inc. of Pensacola, Florida). He was also given 150 cc Amoxicillin (Beecham) I/M, as a prophylactic measure, and a blood sample was drawn.

A basic feeding regime of three smelt with no tails, injected with five cc STAT and five cc tap water was begun three times daily, force fed, along with 400 mg Amoxicillin TID orally and one SEA-TAB (Pacific Research Labs). Each feeding on 20 July was met with resistance and vomiting of some of the fish. On 26 July three injected fish were fed at 0715 and again at 2100. The diet was increased to four smelt on 27 July and 28 July. The Amoxicillin and SEA-TABS were continued for the first week. On 25 July the porpoise weighed 14.85 kg and stayed at that weight until 28 July when he dropped to 14.6 kg. On 29 July another weight loss to 14.2 kg gave the staff great concern. Beginning 29 July we began to tube feed the porpoise with 120 cc STAT and water (50/50). Lactobacillus acidophilus was added to the formula at this time to facilitate digestion. Blood was again drawn.

Beginning 30 July "Wally" was tube fed with 60 cc STAT, 30 cc water and lactobacillus twice daily along with three feedings daily of four whole herring or smelt. He continued to lose weight until 4 August when he weighed only 12.9 kg. On 2 August we initiated a new formula consisting of a base of eight to ten parts herring fillets plus viscera; five parts tap water; two parts STAT; one SEA-TAB; and a small amount of lactobacillus, blended to a smooth consistency.

As of 2 August the porpoise was tube fed every two hours (from 0730 to 1930 hours) 120 cc of five parts of the above formula mixed with three parts water and two parts cream. Ridgeway (1972) indicated that harbor porpoise milk was much higher in fat content than most of the other cetaceans examined.

By 4 August the volume had been increased to 180 cc per feeding. A weight gain to 13.3 kg (on 5 August) remained stable throughout the early part of August and began to rise slowly as the days passed. By 11 August be was being fed six feedings daily of 300 cc each. He continued to be tube fed throughout August and showed a steady weight gain. On 27 August we began to place whole smelt into his throat after the last feeding of the day. This procedure continued until mid-September when he swallowed on his own a whole fish that had been placed just inside his mouth. Formula and periodic whole fish were fed seven times daily until his death on October 17. By this time he had reached a total weight of 16.1 kg.

Measurements taken 17 August showed growth in spite of weight loss. The most significant increase was in total length, which had increased by 7 cm to a total of 93 cm.

From the first day of arrival at the zoo the porpoise was placed in a circular tank of filtered sea water measuring 9.6 m across with a maximum depth of 3 m. Water from Puget Sound was piped to sand filters and then to the pool and not recycled. Water temperature ranged from 11 to 12.2 degrees C during the period form July to October.

Initial use of a standard foal stomach tube to administer the formula brought continued resistance. A one-half inch O.D. highly flexible latex-type tube was located and tried. This type of tubing was so well received that, within days, the porpoise was opening his mouth and readily swallowing the tube on his own with each feeding.

Early on the porpoise began to rub along side the cement edges of the pool. A continuous ring of two-inch PVC piping was placed along the inside edge of the pool and allowed to float. Soon after, neoprene pipe insulation was placed around the PVC. The porpoise seemed to center his attention on the black neoprene, as he would often surface near it and rub it, eliciting a squeaking noise. Without being overly speculative, it appeared to us that the neonate may have actually bonded to the neoprene ring. on numerous occasions the porpoise rolled over, opened its mouth and performed what appeared to be nursing behavior on the ring.

Attempts to introduce other companions were met with disappointment as when on the second day after arrival a mild Beluga whale female was let in with him. Not only did he show signs of panic (rapid swimming, etc.) but so did the whale when she attempted to run him down or corner him against the edge of the pool. The beluga was quickly removed from the pool back to the beluga exhibit. on 4 October we installed a screened gate between the porpoise pool and the Beluga exhibit allowing visual contact between the two areas. A minimal amount of initial increased swimming activity was noted in the porpoise but no apparent major stress.

The porpoise was being kept in the quarantine holding pool for the whale exhibit, thus preventing us from isolating the three Belugas to allow cleaning of their exhibit pool, a procedure normally performed on a weekly basis. We also had passed our scheduled physical exam time for the whales and therefore alternatives to the harbor porpoise occupying the Q-pool were explored. Since attempts to place whales with the porpoise were not working, a 1.8 m circular stock tank approximately 0.6 m deep was placed near the Q-pool and sea water was siphoned into it. The porpoise was placed in this tank for the first time on 8 October and fed in it. No apparent difficulties were noted at this time and he spent the entire day of 9 October in the stock tank while the main exhibit pool and then the Q-pool were cleaned.

On 15 October he was again placed in the stock tank to allow physical exams of the Belugas, which utilizes the Q-pool. This procedure required most of the day and while the porpoise was in the stock tank a blood sample was taken. No apparent problems were noted. He was returned mid-afternoon to the Q-pool and fed as usual. The next day he regurgitated a substantial amount of formula at the noon feeding. We suspected a stomach discomfort, so the later feedings of the day were discontinued. A quantity of gas was passed via the rectum in the afternoon. Few feces were noted that day. At midnight the porpoise was found dead in the Q-pool.

Discussion

The periodic blood samples taken throughout his stay (Chart A) showed minimal changes other than initial stress with elevated alkaline phosphatase, which may be seen in a rapidly growing young animal. Blood values remained essentially level until the final sample when the SGOT (AST) and the SGPT (ALT) were elevated along with the alkaline phosphatase. A lowered RBC and Hct may be the result of internal organ pooling of blood due to stress.

The gross necropsy showed minimal abnormalities with the most significant being isolated to the skin. Areas of superficial rubbing were found as well as one superficial abscess suspected to have been caused by an earlier injection into the area. Both of these areas had been treated topically with a mixture of Novasan ointment (Fort Dodge), zinc oxide and lanolin.

Histopathology confirmed multifocal superficial chronic areas of ulcerative dermatitis and mild congestion of many of the internal organs, but no other significant changes. Gross necropsy had indicated some gas in the intestines but microscopic did not confirm any intestinal infections.

Although no definitive cause of death was determined, we cannot rule out the possibility that multiple stressful activities including, but not necessarily limited to, the ulcerative dermatitis and most especially the confinement to a smaller tank and increased activity surrounding him may have indeed been contributory, with the combined effect of producing a lethal level of psychogenic shock.

In summary, we believe the neoprene ring was a significant contribution to the neonatal care of this specimen. The final formula utilized, including the addition of lactobacillus acidophilus, resulted in substantial growth. The latex tube used in the tube feeding procedure minimized the stress associated with force feeding.

Reference

1.  Ridgway, S.H., 1972. Mammals of the Sea, Biology and Medicine. Charles C. Thomas, Publisher. Springfield, IL, p. 687.