14) Immunology
I am not aware of any studies.
15) Pathological features
Knottenbelt (1990) studied the causes of impala mortality in game farms of Zimbabwe. Stress and injury during capture were the most important causes of death. Next, infection with Fasciola gigantica was a significant problem. They stressed the need for adequate nutrition in winter months. Parasitic infection is another major problem in this species. In a continuing sampling study of animals from Nature Reserves, Horak (1978) found infections with Fasciola gigantica, Gongylonema pulchrum, Haemonchus placei, Longistrongylus sabeii, and with Impalaia tuberculata. They found an increasing load to one year of age, when it reached a maximum. Gallivan et al. (1989) found that 85%+ of impala in Swaziland had infection with Pneumostrongylus calcaratus (lungworm) but, despite this heavy rate of infection and the resulting granulomatous lesions, they felt that this did not pose a significant problem for the animals. Another common infection was described that affected liver nematodiasis (Gallivan et al., 1996). Du Plessis et al. (1997a) identified Ehrlichia platys in the blood platelets of impala, although the animals were apparently healthy. Experimental infection with the organism causing heartwater (Cowdria ruminantium) caused no disease (Peter et al., 1999). The effect of ivermectin therapy in parasitic infections of impala was found to be highly beneficial in a study published by Horak et al. (1983).
Foot-and-mouth disease occurred in the Kruger National Park in 1992, and was recorded by Keet et al. (1996). These authors, and Bastos et al. (2000), identified the viruses recovered from impala and buffalo. Anderson et al. (1993) found seropositive impala following the epidemic. The virus responsible for malignant catarrhal fever of ruminants has also been identified in impalas (Heuschele et al., 1984). Gummow et al. (1991) showed a correlation of copper toxicity in ruminants of the Kruger Park with the distance from copper smelters. They shot 26 impala and measured the copper levels and also studied two dead impala, apparently the result of intoxication. These latter animals showed hepatic and renal toxicity, and this was presumably the result of hemolysis. Grobler (1999) showed that the copper concentration of surface soil and plants was significantly elevated near the copper-smelting plant and thus probably correlated with copper poisoning of impalas. Subsequently, Grobler & Swan (1999) attempted to produce copper poisoning in captive impalas but failed to induce the illness. Ackerman et al. (1999) identified vacuolar lesions in the spermatozoal neck region that correlated with copper levels and general body condition.
Griner (198) did necropsies on 88 impala at the San Diego Zoo and found trauma and sequelae of stress or malnutrition (in young) the most common causes of death. One uterine adenocarcinoma was also found.
16) Physiologic data
Platelets were found to be exceedingly small in a study by du Plessis et al. (1997b). Karesh et al. (1997) examined blood parameters and serologic titers in black-faced impala of Namibia during a translocation operation. They found antibodies to bovine rhinotracheitis virus and bovine viral diarrhea. Pitts & Mitchell (2003) compared the hydrolysis of succinylcholine in elephants with that in impala and found it to be very significantly shorter in elephants. Cheney & Hattingh (1988) recommended that xylazine should be added to etorphine during the immobilization of impala.
17) Other resources
At present we have cell lines of Kenyan and black-faced impala, all with 2n=60 at CRES of the San Diego Zoo. They can be made available through contacting Dr. O. Ryder at oryder@ucsd.edu.
18) Other remarks - What additional Information is needed?
No early stages of implantation are available and there are no data on endocrine parameters during gestation.
Acknowledgement
The animal picture was kindly made available by the department of photography at the San Diego Zoo. Dr. Petr Hradecky kindly made slides available of freshly fixed material.
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