Abstract

A study of naturally occurring diseases in a cetacean population was undertaken on 41 specimens from a herd of approximately 150 stranded L. acutus. The most prevalent lesions were parasitic in origin; these included mastitis associated with the nematode Crassicauda grampicola, and biliary and pancreatic fibrosis associated with the trematode Oschmarinella laevicaecum. Other parasites commonly found were Phyllobothrium delphini and Monorygma grimaldi plerocercoids in the blubber and abdomen, Crassicauda sp. in the fascia, Stenurus globicephalae in the cranial sinuses and lungs, and Tetrabothrius forsteri cestodes in the duodenum.

Arteriosclerosis of major vessels, and adrenal cortical nodules were widespread among the dolphins. These were not associated with any obvious functional disturbances. Incidental findings included leiomyomas of the intestine, papilloma-like growths on the penis and on the pharyngeal mucosa, and an expansive bone growth on a rib.

Notes

Lagenorhyncus acutus is an off-shore animal.

Pathology

• Jaw lesions
  Due to seagull pecking after stranding, with a predilection for the commissure of the mouth.

• Crassicauda sp.

  • Long torturous tracts were found under the fascia. This parasite infects young animals and is present by 1 1/2 years of age. It is viable only in the young animal and calcifies as the animal ages.

  • Cysts in muscle

  • Abscesses in mammary gland. Fibrosed greenish granules were scattered throughout the parenchyma. Seventy-seven percent of all females had lesions due to Crassicauda. The 25 cm long adult can be found in the lactiferous mammary ducts, causing degeneration and fibrosis of the ducts. The pathological changes in the mammary gland may marginally impair the growth of calves. The ova exit via the milk. It is possible that the parasite travels through the fascia making tortuous tracts in quest of the mammary gland.

• Phyllobothrium cysts in blubber
  Plerocercoids are all found in the genital region, especially immediately adjacent to the genital opening. It may be in this region because it is nearest to the gut exit. The dolphin may possibly be the intermediate host for this parasite, with the skate or ray being the definitive host.

• Plerocercoid of Monorygma grimaldi
  This occurs in the abdominal cavity, especially in females. It is most commonly located around the reproductive tract, in the region of the ovaries.

• Tetrabothrius forsteri
  Fifty-six percent of the animals had lesions due to this parasite. Biliary and pancreatic fibrosis were seen.

• Stenurus globicephalae
  

  This parasite was found in the middle ear and cranial sinuses, associated with inflammatory changes. Since the mechanism of action is unknown, research is being done to see if the parasite is breaking through the round window to the inner ear.

• Viral warts

• Leiomyomas

• Possible aneurysmal bone cyst

• Adrenal cortical hyperplasia and nodular hyperplasia was noted in 51% of the animals. This type of change is seen in man, associated with stress. These changes can functionally impair the adrenal gland.

• Arteriosclerosis of major vessels occurred in 44% of the animals. Fifty-eight percent had sub-endocardial calcification.

  Age at which certain parasites appear in L. acutus:

  Parasite	I. forsteri		P. delphini
  	S. globicephalae	Crassicauda sp.	C. grampicola	M. grimaldi
  Age	1 year	1 1/2 years	1 3/4 years	2 years