The Przewalski horse (Equus prezwalskii) became extinct in the wild during the 1960s. The last
recorded sightings of Przewalski horses, also called takhi, in Mongolian, occurred in the Dzungarian Gobi in Southwest
Mongolia.8,10 Whether this area is representative of past takhi range land or was merely the last refuge for this
species prior to extinction in the wild has been debated and has resulted in a desert-steppe controversy.2,9
However, Mongolian Government-UNDP sponsored recommendations for the reintroduction of takhi suggested establishing multiple
sites with a primary free-ranging self-sustaining population in the Dzungari Basin of the greater Gobi Desert.7
Projects that in the past strongly defended steppe reintroduction have lately also suggested that multiple sites in
different habitats should be established.12 At the present, six different takhi reintroduction projects exist:
two in Mongolia at Hustain Nuruu12 and Tachin Tal,11 two in China at Jimsar and Gansu,11
one each in Kazakhstan and Ukraine.3,12 Only the two projects in Mongolia have successfully released horses to
the wild. It is questionable whether the Chinese projects will ever be able to release the horses to the wild considering
the socio-economic and geo-morphologic restraints imposed on the potential release sites.11 No information is
available to the authors at the present concerning the status of the last two projects.
The Tachin Tal Project was initiated by the German Christian Oswald Stiftung (COS) and the Mongolian
Society for the Conservation of rare animals (MSCRA) of the Ministry of Environment with the support of various
international sponsors. In 1999 the International Takhi Group (ITG) was established to continue and extend this project in
accordance with the IUCN reintroduction guidelines.
In 1992 the first group of zoo born takhi arrived at the Tachin Tal site (45.53.80 N, 93.65.22 E) at the
edge of the 12500-km2 Gobi-B Strictly Protected Area and International Biosphere Reserve. Subsequent transports
were carried out in 1993 and yearly between 1995 and 1999. A total of 59 horses have been transported to date. In 1997, the
first harem group was released from the adaptation enclosures. In 1999, the first foals were successfully raised in the
wild. At the present three harem groups and one bachelor group have been released (n = 31).
A discussion of the basic requirements and considerations of a reintroduction program greatly exceeds
the scope of this abstract and the reader is referred to the IUCN document on translocations5 and
Before selecting animals for the transport to Southwest Mongolia certain health criteria must be
fulfilled. These are demanded by the Mongolian veterinary health officials and the IUCN reintroduction specialist group. The
horses must not be a health risk for domestic livestock, for other equids (e.g., Kulan E. h. hemionus) and other
species in the reintroduction area. The potential danger to free-ranging Przewalski horses also exists following the first
releases in 1997.
After receiving a thorough clinical examination, all animals were placed in a 30-day pre-shipment
quarantine. The clinical examination took diseases or lesions described in Przewalski horses (e.g., cleft palate,
degenerative myelo-encephalopathy) into consideration. Additionally, all horses were bled prior to shipment and serologic
examinations were carried out for the following diseases: equine infectious anemia (lenti virus), equine arteritis (toga
virus), vesicular stomatitis (rhabdo virus), glanders (Pseudomonas mallei) and contagious equine metritis
(Taylorella equigenitalis). Bacteriologic examination for Trypanosoma equiperdum was carried out. As of 2000,
serologic screening will be expanded to include equine viral pneumonitis and abortion (equine herpes virus 1 and 4), equine
coital exanthema (equine herpes virus 3) and equine influenza. Vaccination will be expanded to include equine herpes virus
1+4 (Reosequinplus® Hoechst Roussel Vet, Vienna). It is important to note that a modified live virus vaccine (e.g.,
Prevaccinol® Centeon Pharma, Marburg) should not be used in reintroductions as these have the inherent risk of a virus
The horses received two doses of a broad-spectrum anthelmintic (Ivomec-P®, Merck Sharpe &
Dohme, Haarlem) and were vaccinated against equine influenza and tetanus (Prevacun FT®, Hoechst Roussel Vet, Vienna).
Special attention must be given to the crate dimensions and specifications to ensure a safe trauma free
transport to the reintroduction site. Total transport time can reach 50 hr in some cases. Crates must be smooth on the
inside and cushioned with neoprene foam. The floor must be slip-proof even with urine present. The animals are provided with
water and hay during journey breaks. However, the uncontrolled provision of hay has proven detrimental. The horses tend to
shove the hay to the rear of the crate with their hooves and therefore create an uneven floor. One horse was lost as he
managed to turn onto his back during the transport. Similar problems have been encountered in other Przewalski horse
transports (Bouman pers.comm., Zimmermann pers. comm.).
To reduce the potential stress related to transport, several horses have been treated with the long
acting neuroleptic drug perphenazine enantate (Decentan® Depot, Merck, Darmstadt) prior to shipment. Perphenazine at
150 mg/horse will be used on all future shipments.
Veterinarians not only accompany the shipments to Mongolia, but also are on hand to provide help in
cases of shipment trauma and exhaustion. The long term veterinary care is provided on-site by Mongolian veterinarians
employed by the project. As of 1999 and the installation of a permanent research facility at the Tachin Tal site, they are
aided by European veterinarians in doctoral research programs. Two doctoral programs are presently underway to survey the
dynamics and influence of parasites in the equids of the release area and to investigate the reproductive biology and
possible influence of stress (defined by fecal cortisol metabolites) on the takhi.
Information gained from necropsies carried out on site in the past has been scant. This led to the
establishment of a basic necropsy protocol and adequate sample collection procedures. Analysis of the past deaths (Figure 1)
revealed that a total of 41% of the deaths had been attributed by local pathologists to "lung problems" and "effects of
sandstorm." Furthermore a significant increase in deaths was noted in the months April-May. In 1999 it was possible for the
first time to examine histopathologically formalin fixed samples (n = 4).
The prominent pathologic features in three animals were congestion of the lungs with pulmonary, alveolar
and interstitial edema accompanied by fibrin, erythrocytes (hemorrhage) and few macrophages and other inflammatory cells, a
highly congested spleen, the presence of hemosiderin-laden macrophages in different organs, and a moderate mixed cellular
infiltration in the portal fields in the liver. One animal showed severe renal lesions characterized by necrotizing
tubulonephrosis, multifocal interstitial hemorrhages, and presence of numerous protozoan organisms (Klossiella equi)
in the tubular epithelial cells. The pathologic lesions, especially the pulmonary edema, the generalized capillary
congestion and the highly congested spleen, the tubulonephrosis and the hemosiderin-laden macrophages in different organs
(indicative for hemolysis), associated with the clinical data, are suggestive, but not conclusive for an infection with
Babesia equi or B. caballi (piroplasmosis). An immunohistologic examination of the tissues for African horse
sickness (orbi virus) the most important differential diagnosis was negative. Other possible viral causes such as herpes or
influenza could not be definitely excluded at the time of print. The renal protozoan K. equi has been diagnosed in
two animals and is considered an incidental finding or opportunistic agent. The possible infection with Babesia has
been further reinforced through the serologic examination of three serum samples from the Tachin Tal. Two horses, which had
been in Mongolia in the spring prior to sampling, had positive antibody titers against B. caballi. The third horse,
which arrived in the summer months, was negative. These initial data indicate that the naive horses are potentially infected
with Babesia during their first spring in the Tachin Tal. At that time every year a massive infection with
Dermacentor nutalli ticks had been noted. A review of the literature revealed that the prevalence of equine
piroplasmosis in Mongolia and in neighboring northern China is extremely high.1,13 That piroplasmosis is
potentially an important mortality factor in combination with exertion and stress has been demonstrated in the
past.4 The influence of piroplasmosis as a pathogen and important mortality factor or co-factor will be
investigated in the coming months. Furthermore, acaricide treatment, and if necessary Imidocarb or Diminazene treatment,
will be implemented and monitored as of 2000. This example clearly demonstrates the importance of a thorough disease risk
assessment prior to shipment.
Anesthesia is an additional component of the veterinary care in Mongolia. It is necessary for
therapeutic sampling procedures and the placement of radio-collars for monitoring purposes. Standard Immobilon®
protocols have been adapted for procedures in Mongolia. A combination of etorphine, detomidine and butorphanol is presently
being used. This combination has the advantage of reducing the pacing phase during induction and therefore reducing the risk
of trauma. Veterinarians are presently also involved in all aspects of management and research in the Tachin Tal project.
This project has demonstrated that Przewalski horses can successfully be reintroduced into the
semi-desert environment of the Dzungarian Gobi in Mongolia. However, many procedures and methods are incomplete and have to
be improved in future years to ensure that a self-sustaining population can be established at this site. A
multi-institutional co-operative approach between biologists, botanists, veterinarians and other specialists from the
various projects will be necessary to fulfill the goal of returning this species to the wild in Mongolia.
Przewalski horse (Equus prezwalskii) causes of death in Tachin Tal in the period 1992-1999.
The authors thank all staff and co-workers on site in Mongolia, members of the ITG in Europe
especially Christian Stauffer and all students past and present involved in the Project. Furthermore, we thank Dr. Peter
Wohlsein for performing the IHC for African horse sickness.
1. Avarzed A, DT De Waal, I Igarashi, ASaito, T Oyamada, Y Toyody, N Suzuki. 1997. Prevalence
of equine piroplasmosis in central Mongolia. Ond. J. Vet Res. 64: 141-145.
2. Bouman DT, JG.Bouman. 1994. The history of Przewalski's horse. In: L. Boyd, and D.A. Houpt
(eds.): Przewalski's Horse. The history and biology of an endangered species. State University of New York Press,
Albany. Pp. 5-38.
3. Duncan P. 1992. Zebras, asses and horses: an action plan for the conservation of wild
equids. World conservation Union/SSC Equid Specialist Group, Gland Switzerland.
4. Hailat NQ, SQ Lafi, AM Al-Darraji, FK Al-Ani. 1997. Equine babesiosis associated with
strenuous exercise: clinical and pathological studies in Jordan. J. Vet. Parasitol. 69: 1-8.
5. International Union for Conservation of Nature and Natural Resources (IUCN). 1987.
Translocations of living organisms: introductions, re-introductions and re-stocking. IUCN council position statement. Gland,
6. Kleiman DG. Reintroduction programs. 1996. In: D.G. Kleiman, M.E. Allen, K.V. Thompson, and
S. Lumpkin (eds.): Wild Mammals in Captivity. Principles and Techniques. The University of Chicago Press, Chicago,
London. Pp. 297-305.
7. Mongolia Takhi Strategy and Plan Work Group. 1993. Recommendations for Mongolia
´takhi strategy and plan. Mongolian Government, Ministry of Nature and Environment, Ulaan Baatar.
8. Ryder OA. 1995. Genetical analysis of Przewalski horse in captivity. In:V.E. Sokolovand,
V.N. Orlov (eds.): The Przewalski Horse and its Restoration in Nature in Mongolia. Proc. of an FAO/UNEP Meeting,
Moscow, CMP GKNT. Pp. 50-103.
9. Ryder OA. 1993 Przewalski's horse: prospects for reintroduction into the wild. Cons.
10. Sokolov VE, G Amarsanaa, MW Paklina, MKPosdnjakowa, EI Ratschkowskaja, N Chotoluu. 1992. Das
letzte Przewalskipferd Areal und seine geobotanische Charakteristik. Proc. 5th. Intern. Symp. On the preservation of the
Przewalski Horse. Zoologischer Garten Leipzig, Leipzig, Germany.
11. Stauffer C, E Isenbügel. 1998. Die Wiederansiedlung des Przewalskipferdes in der Mongolei.
Infodienst Wildbiologie & Oekologie.
12. Van Dierendonck MC, MF Wallies de Vries. 1996. Ungulate reintroductions: experiences with the
takhi or Przewalski horse (Equus ferus przewalskii) in Mongolia. Cons. Biol. 10: 728-740.
13. Yin H, W Lu, J Luo. 1997. Babesiosis in China. Trop. Anim. Health Prod. 29: 11s-15s.