Abstract

A juvenile (2.5 kg) Kemp's ridley sea turtle (Lepidochelys kempi) stranded on 18 Nov. 1997 in Eastham, MA. Upon presentation to the New England Aquarium, the animal's body temperature was 12.7°C and the animal appeared moderately dehydrated. Intracoelomic fluid therapy (2.5% dextrose in 0.45% saline and lactated ringers in a 2:1 ratio) was initiated at 1.5% body weight twice daily (BID). The animal was held out of water for several days and its body temperature was increased by approximately 2°C per day to 24°C. A complete blood cell count and plasma chemistry profile upon presentation showed elevated packed cell volume (50%: mean = 30.1%, SD +/- 3.0%) and mildly elevated white blood cell (18.8 x 10³cells/ul: mean = 5.2x 10³ cells/ul, SD +/- 1.5 x 10³ cells/ ul) count (via Eosinophil Unipette method) indicating dehydration and possible inflammation and / or infection.^9,10 The turtle became more active as its body temperature elevated and within a week of presentation it was introduced to water. The animal began eating live green crabs, herring and squid 10 days after it began to swim. Due to intermittent eating, vitamin supplementation was withheld for the first month due to decreased food palatability.

The animal had clinical signs consistent with pneumonia which included abnormal buoyancy. A tracheal wash was performed prior to empirical dosing with ceftazidime (Fortraz®, Glaxo Wellcome, Research Triangle Park, NC 27709 USA; 20 mg/kg q72hrs intramuscularly (IM)) and fluconazole (Diflucan®, Pfizer, New York, New York, 10017, USA; 0.75 mg/kg every other day (EOD) IM). Tracheal cytology results were moderate to marked numbers of inflammatory cells and small numbers of erythrocytes. There was a predominance of heterophils with lesser numbers of lymphocytes and macrophages. An etiologic agent was not apparent. Aerobic cultures yielded Pseudomonas sp., Stenotrophomonas maltophilia, and E. coli. Anaerobic and fungal cultures yielded no growth. Based on culture and sensitivity, the antimicrobial therapy was changed to enrofloxacin (Baytril® Bayer, Agricultural Division, Animal Health, Shawnee Mission, Kansas 66201 USA; 10 mg/kg EOD IM).

In January of 1998, the animal was clinically improved from the previous weeks. It had increased in activity, weight gain and appetite. On January 7th, firm areas (multiple sizes ranging from approximately 0.3 cm to 1 cm in diameter) in the inguinal region were noted on physical exam. These areas became more firm and began to develop more distinct borders over the next two days. On January 9th, multiple firm subcutaneous masses were easily palpated over the inguinal, shoulder and neck areas ranging in sized from 0.3 cm to 3.0 cm in diameter. Ultrasound examination confirmed diffuse masses of soft tissue density through the cervical region. An excisional biopsy was attempted, but the mass was associated with the cervical venous sinus and appeared to extend in multiple directions within the subcutaneous adipose tissue. As a result, two subsamples (0.5 cm x 0.5 cm and 0.3 cm x 0.3 cm) of the abnormal tissue were removed. The mass was yellow-brown and lacked a defined capsule. Histologic examination of the tissues showed chronic, focally extensive cellulitis with steatitis. Subacute inflammation was prominent in perivascular sites extending along the connective tissue, coalescing and fingering out into the adipose tissue. Special stains consisting of Gram, silver, and acid fast stains did not show bacterial or fungal agents.

Differentials for steatitis include nutritional deficiency, sepsis, vasculitis, and hypothermia. The animal was started on oral multivitamin supplementation (Daily Vitamins®, Moore Medical, New Britain, CT 06050 USA) and antimicrobial therapy was continued. Two months later additional vitamin E (100 IU/kg of food) and Thiamine (50 mg/kg of food) were added to the regime. After five months, no distinct masses could be palpated in the inguinal area. The masses in the neck were still present and did not appear to change in size, but the animal also had cervical fat that palpated normally. A second biopsy, taken nine months after the first, showed fibrous encapsulation of necrotic adipose tissue with a mild inflammatory infiltrate suggesting that the condition was slowly resolving. The animal continued to grow and gain weight. The biopsy site was healing and the masses were still palpable in the neck region. No additional masses were noted after the original occurrence. Consequently in November of 1998, one year after initial presentation, the turtle was transported to the Sea Turtle Hospital in Marathon Key, FL USA where it was acclimated and monitored for an additional month before release in Florida Bay, FL USA.

The etiology of this animal's condition is unclear. Nutritionally induced steatitis has been reported in crocodiles, alligators, pigs, cats and snakes fed a predominately fish diet.^{3, 4,5,6,7} Frozen fish can contain a high amounts of polyunsaturated fats with low amounts of vitamin E. A nutritional cause cannot be ruled out, as this animal's diet was unknown prior to presentation at the New England Aquarium and, a diet high in polyunsaturated fats without vitamin supplementation was initially offered for one month. However, histologic and clinical findings could not specify this as the cause. The cellulitis and secondary steatitis could also be secondary to infection and sepsis. Although microbial agents were not detected within the lesions, this turtle was diagnosed with pneumonia. It has been demonstrated that microbes from within the lungs can spread to the blood.² The cellulitis with secondary steatitis could have resulted from vasculitis. Causes of vasculitis include viral infection, toxic insult and trauma. One of the most intriguing differentials for subcutaneous fat necrosis is hypothermia, which has been reported in children.¹ Although the pathophysiology of this condition is unknown in humans, it is thought to be a result of abnormal fat composition or metabolism coupled with cold exposure.⁸ Histologic findings seen in human patients with "Cold Panniculitis" include "a perivascular infiltrate of lymphoid and histiocytic cells at the dermal-subcutaneous junction in the early phase of the reaction. After 48-72 hours, a well developed panniculitis appears." ¹ One test used to aide in the diagnosis of this disease involves placing an ice cube on a non-affected area monitoring the area for formation of tender nodules.¹ The "ice cube test" was not performed on this animal. Although the etiology of the steatitis is unclear, this is the first reported case of multifocal steatitis lesions in a Kemp's ridley sea turtle.

Acknowledgements

The authors wish to thank Connie Merigo, Kristen Dube', Jim Rice, Belinda Rubinstein, Kristen Patchett, Bob Cooper, Dr. Beth Chittick and Dr. Rose Borkowski for their hard work in rehabilitating this animal. We also wish to thank the Sea Turtle Hospital in Marathon Key for their assistance. And finally, thanks to Dr. Andy Stamper for his help.

References

1.  Aroni K. 1998. An unusual panniculitis appearing in the winter with good response to tetracycline. The Journal of Dermatology 25:677-681.

2.  Dow S. 1995. Diagnosis of bacteremia in critically ill dogs and cats. In: Current Veterinary Therapy XII, WB Saunders Company, The Curtis Center, Independent Square West, Philadelphia, PA, 137-139.

3.  Kirby S. 1981. Steatitis in fattening pigs. Veterinary Record 109:385.

4.  Koutinas AF, WH, Miller, M Kritsepi, S Lekkas. 1993. Pansteatitis (steatitis, "yellow fat disease") in the cat: a review article and report of four spontaneous cases in 1993. Veterinary Dermatology 3:101-106.

5.  Ladds PW, H Mangunwirjo, D Sebayang, PW Daniels. 1995. Diseases in young farmed crocodiles in Irian Jaya. Veterinary Record 136:121-124.

6.  Larsen RE, C Buergektm, PT Cardeihac, ER Jacobson. 1983. Steatitis and fat necrosis in captive alligators. Journal of the American Veterinary Medical Association 83,11:1202-1203.

7.  Ruso E. 1987. Diagnosis and treatment of lumps and bumps in snakes. Compendium Small Animal Medicine 9:8:795-802.

8.  Silverman AK, EH Michels, JE Rasmussen. 1986. Subcutaneous fat necrosis in an infant, occurring after hypothermic cardiac surgery. Journal of the American Academy of Dermatology 15:331-336.

9.  Smith C. Personal Communication.

10. Whitaker BR, H Krum. 1999. Medical Management of Sea Turtles in Aquaria. In: Fowler, ME. And Miller R.E. Eds. Zoo and Wild Animal Medicine Current Therapy 4. W.B. Saunders Company, PA 217-231.