 Reference Base  Veterinary medicine in North American rhinoceros programs |
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Miller, R.E., 1995. Veterinary medicine in North American rhinoceros programs. Around the Horn 3 (1): 13-15
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World |
| Subject: |
Diseases |
| Species: |
All Rhino Species |
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Several diseases of large animals, such as tuberculosis, can presumably affect all rhinoceros species (in rhinoceroses, infection with Mycobacterium bovis has been most frequently reported). Although the data are inadequate to make definitive testing recommendations, it is of interest to note that several infected animals have had positive reactions with intradermal PPD bovis in the eyelid. Any reactors should have mycobacterial cultures performed on tracheal and/or gastric lavage samples for confirmation.
Leptospiral infection has been indicated in some of the black rhinoceroses undergoing hemolysis, and has also been identified in an aborted fetus from a greater Asian one-homed rhinoceros (Rhinoceros unicornis). In the black rhinoceros, vaccination with a leptospiral bacterin containing five serovars has been recommended (Leptoferm-5, Norden Lab. Inc., Lincoln, Nebraska, USA). Excessive build-up of oral plaque has been noted in several captive black rhinoceros, and a thorough oral examination of all anesthetized rhinoceroses is warranted.
Black Rhinoceroses
Diseases of black rhinoceroses are characterized by several syndromes of unusual nature and uncertain etiology or pathogenesis. These include hemolytic anemia, mucocutaneous ulcerative disease, encephalomalacia, hemosiderosis and fungal pneumonia. Hemolytic anemia has been identified as the leading cause of death in captive black rhinoceros. Since leptospiral infection did not account for all of the hemolytic cases, a series of investigations was initiated to determine if properties of the black rhinoceros red blood cell (RBC) could account for the liemolysis. The most significant and promising findings to date have resulted from studies of RBC metabolism. In light of the metabolic findings, exposure to oxidative agents and many drug compounds should be avoided (e.g., bleaches, drugs like isoniazid). In several cases, a marked hypophosphatemia has developed with the hemolysis and may, in it- self, contribute to red cell destruction. Additionally, plants and compounds, such as red maple or members of the Brassica family, that cause hemolytic anemia in domestic animals should also be carefully avoided in rhinoceroses.
A syndrome mucocutaneous ulcers has also had a major impact on captive black rhi- noceroses (45+ cases identified). The first signs are often small vesicles or ulcers over points of wear, that may progress to cover large areas of the body. There may be spontaneous regression, however, in some cases, thesyndrome may lead to death. At the present time, the etiology remains unknown.
Infection with the skin parasite ,Stephanofilaria dinniki has not been seen in captive animals, nor have any of the North American cases been associated with viral infections. A marked response to corticosteroid therapy has been noted in some cases; however, this also appears to predispose individual animals to fungal pneumonia. Although many of the cases of fungal pneumonia (primarily Aspergillus sp.) have been on immunosuppressive therapy, nearly 50% have occurred spontaneously.
Encephalomalacia, primarily affecting white matter, has been noted in three calves and one 2-year-old black rhinoceros.' The neurological signs have been variable, so histological examination of brain tissues is warranted in all rhinoceros deaths. Additionally, accumulation of iron in the tissues of black rhinoceros has been shown to be correlated with length of time in captivity. Lastly, exposure to creosote has been associated with a syndrome of liver failure, and so should be carefully avoided in all species of rhinoceroses.
Sumatran Rhinoceroses
Although the number of Sumatran rhinoceroses held in western captivity has been limited, their medical histories have been notable. Causes of death have included intestinal torsions, a uterine mass (in Great Britain), and histology results are pendi on two additional deaths. There are indications that another captive female may al have uterine abnormalities.
Greater Asian One-Homed Rhinoceros
Diseases of greater Asian one-homed rh noceroses have been notable for an apparently increased incidence of abortion (note above that one case was associated with leptospiral infection), foot problems includi chronic infections, and uterine leiomyomas.
White Rhinoceros
In contrast to the diseases of the other rhinoceros species, those of the white rhino (Ceratotherium simum) appear to more similar to those of large domestic an mals and of an apparently lower incidence.
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