Abstract

In June of 2007 a nine-year-old female, Callorhinus ursinus Linnaeus, captured in 2000 near the Commander Islands (Russian Federation) and kept in Sevastopol Dolphinarium (Ukraine) open air sea enclosure, displayed discoloration (from dark-brown to light-brown with pink tint) of the skin of its fore and hind flippers, as well as the fur around its nose and eyes. Prior to this clinical change the animal's health had been unremarkable. The diet consisted of capelin, scad, smelt, pollack, purplehead and squid with vitamin supplementation ("Quadevitum" plus Vitamins B₁, E, C and folic acid admixture).

The results of blood testing, performed July 3rd (Table 1), revealed an apparent lowering of red blood cell (RBC) count and hemoglobin (Hb) content against the background of a moderate ESR increase, minimal leukogram changes, normal level of serum iron, as well as increases in total proteins and albumins. The anemia was interpreted as normocytic and normochromic. The animal's health began to deteriorate during the next week which involved inappetence, inactivity, and weight loss. On the 9th of July the animal became extremely depressed, dyspneic, began shivering, and became completely inappetant. Hematological data (Table 1) revealed a worsening anemia a rise in erythrocyte sedimentation rate (ESR), a relative neutrophilia with left shift, lymphopenia, eosinophilia, decrease in serum iron level and a considerable increase of globulins, suggesting the development of infectious-inflammatory process.

The animal was treated with dexamethasone (0.32 mg/kg IM, initially with reduction to 0.24 mg/kg during the next two days), a combination of ceftriaxone (15mg/kg IM SID) plus amikacin (7 mg/kg IM BID), and subcutaneous 5% dextrose solution and saline (40 ml/kg daily). The animal's general state improved (as evidenced by the reaction to attendants and improvement of appetite and activity) within three hours of starting therapy; however the shivering remained and was treated with a single dose of paracetamol (10 mg/kg PO).

In the next two days the seal was quite active in the morning hours (swam most of the time and willingly accepted fish), but hauled out in the afternoon, became depressed, and began open mouth breathing while preferring to lie down on its back or side. By the evening of July 11th the tremor was noted again with signs of severe abdominal pain and convulsions of the lower part of the body. Hematological data (Table 1) showed the further drop in RBC and Hb content, ESR increase on the background of marked left shift in neutrophils (perhaps due to the use of dexamethasone), lowering of the platelet count, and also a considerable decrease in albumin.

A polyresistant culture of Citrobacter freundi was isolated from the vagina, anus, nasal cavity, and stomach. Taking into consideration the sensitivity of the microorganism to antibiotics we started to use cefepime (30 mg/kg IM BID) in combination with amikacin. We continued rehydration and steroid treatment, switching from parenteral dexamethasone to oral prednisolone in the equivalent, smoothly reducing doses.

The seal's state of health eventually stabilized during the following week. The appetite and activity improved slightly and the signs of abdominal pain disappeared. Nevertheless, the results of hematological examination (July 18th, Table 1) showed further worsening of anemia progressing against the background of a stress leukogram and normalization of serum iron. After the restoration of feeding activity, the treatment was continued with a two-week course of enrofloxacin (5 mg/kg PO BID) and probiotic (Bifiform, 1 capsule PO BID). The steroid therapy was discontinued on July 24th.

During the following three weeks the seal's health remained satisfactory; the normal color of skin and hair was gradually restored, but the feeding activity remained reduced by up to 50% of the requirement for this animal. At the same time peripheral vessel thromboses were noted. A control blood test on August 12th (Table 1) showed that the anemia, which was first noted nearly six weeks previously had worsened necessitating treatment with subcutaneous Recormon (β-Erythropoietin, 2000 IU, two injections every four days). Over the next two weeks the animal improved clinically and hematological improvements were noted (as evidenced by an increase in the reticulocytes count, RBC and Hb levels). At the same time coagulation necrosis of affected extremities including tips of both hind and foreflippers was noted. In the middle of September the general state of the fur seal's health started to deteriorate once again. Recormon was started again at a schedule of every three days in an attempt to stabilize the blood picture, however the animal continued to decline and died on October 5, 2007.

The histological examination revealed a picture of hemolytic (possibly autoimmune) anemia with the features of increased erythrocyte destruction, marked hemosiderosis of splenic red pulp, macrophage hyperplasia within the sinuses, and hemosiderophage appearance within the sinuses of the lymph nodes. Intrahepatic cholestasis was also noted. The foci of extramedullary hematopoiesis with the prevalence of the myelo-erythroid cells (probably, the effect of Recormon usage) were discovered in liver, kidneys, adrenal glands and lymph nodes. PCR assay revealed the adenovirus genome in the lungs, kidneys, liver, and brain.

The etiology of the hemolytic anemia in this fur seal remains unclear. In our opinion, the Citrobacter freundi contributed greatly in the disease development and the adenovirus infection most likely was an immunosuppressive factor.

Table 1. Results of hematological examinations.

Acknowledgments

The authors would like to thank Dr. L.I. Efanova from State Research Veterinary Institute of Pharmacology, Pathology and Therapy, Professor O.Y. Kaufman, and veterinarian D.V. Tsvetkova from Sevastopol Dolphinarium for their professional assistance with this case.