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COMBELEN© AS A POSSIBLE CHEMICAL AGENT FOR THE IMMOBILIZATION OF 
PRIMATES IN CONSERVATION AND OTHER PROJECTS

Clara B. Jones Community Conservation, Inc. Livingstone College The worldwide biodiversity crisis, 
induced by anthropogenic factors (e.g., habitat destruction, hunting: Myers et al., 2000; Cowlishaw 
and Dunbar, 2000; Jones, 1997), has generated a new discipline ("conservation 
biology") with its own set of descriptive and hypothetico-deductive programs.  Translocation 
("artificial dispersal," the movement of one or more organisms from one location to another: Jones, 
1999 and references therein) and other procedures (e.g., restocking and reintroduction: Cowlishaw 
and Dunbar, 2000, Chapter 11) requiring immobilization of animals (e.g., to evaluate health status) 
are often required for the implementation and/or completion of these projects.  Malik and Johnson 
(1991), for example, translocated Rhesus monkeys (Macaca mulatta) in India from a crowded to a 
low-density region, enhancing opportunities for successful growth and/or reproduction.  Horwich 
et al. (1993) reported their classic translocation of Belizean black howler monkeys (Alouatta pigra) 
from fragmented to less disturbed habitats.  Rodriguez-Luna & Cortés-Ortiz (1994) described 
translocation of mantled howlers (A. palliata) from fragmented forests in Mexico to a secure 
island environment.  In each of these cases, immobilization was effected with chemical agents 
administered by capture rifle. The most common method of immobilization in primate projects 
involves the use of chemical agents, particularly Ketamine hydrochloride (KH) or Tiletamine 
hydrochloride (see Ancrenaz et al., 2003; Glander et al., 1991; Scott et al., 1976).  The relative 
advantages and disadvantages of these drugs are discussed in these reports in addition to modes of 
administration and other methods and procedures.  

Here, I report that, in addition to KH, I have used Propionyl promazine (COMBELEN©, Bayer Chemical, 
http://www.sanidadanimal.com/productos/combelen)  to immobilize primates in Costa Rican tropical dry 
forest (Frankie et al., 1974).  This chemical agent appears to have several advantages 
in comparison with KH. During eight years of intermittent 
research (1973-1980) in Guanacaste, Costa Rica (e.g., Jones, 1980, 1982, 1994), mantled howler 
monkeys (A. palliata) were immobilized with a capture rifle to obtain morphometric data, to mark 
animals or to replace marks, to assess animals' physical condition (e.g., ectoparasites), and to 
conduct experiments.  When not using KH in association with the research efforts of Dr. Norman J. 
Scott, Jr (Fish and Wildlife Service, USA) at Hacienda La Pacífica, Cañas, Guanacaste, Costa Rica, 
I purchased COMBELEN©, after consultation with a veterinarian, without permit or prescription from 
an agricultural supply house.  Following specifications indicated in the instructions accompanying 
the drug and using a capture rifle provided by Scott, I proceeded to immobilize animals when 
necessary for my ongoing projects.  

COMBELEN© had three clear advantages over KH: 
(1) it was easily available in Costa Rica; 
(2) it was inexpensive; and, 
(3) it relaxed the prehensile tail of mantled howlers more effectively than KH, with direct 
    benefits for the safe and rapid retrieval of these arboreal monkeys.  

In my opinion, fewer accidents and consequent injuries as well as fewer deleterious 
side effects were associated with the use of COMBELEN© compared with KH; however, these speculations 
require documentation.  Of course, as pointed out by Ancrenaz et al. (2003), numerous factors determine 
the successful use of chemical agents in the field with primates. In conclusion, it is suggested that 
COMBELEN© may be a robust alternative chemical agent to KH and other drugs commonly used for the 
immobilization of primates in conservation and other projects.  Research is required to document the 
apparent advantages of COMBELEN©, particularly for studies with arboreal primates and with 
prehensile-tailed monkeys.  It is especially noted that COMBELEN© is readily available in habitat 
countries.     

References: 

Ancrenaz, M., Setchell, J.M., & Curtis, D.J. (2003). 
Handling, anesthesia, health evaluation and biological sampling. 
In J.M. Setchell & D.J. Curtis (Eds.), Field and laboratory 
methods in primatology (pp. 122-139). 
Cambridge: Cambridge University Press. 

Cowlishaw, G., & Dunbar, R. (2000). 
Primate conservation biology. 
Chicago: The University of Chicago Press. Frankie, 

G.W., Baker, H.G., & Opler, P.A. (1974). 
Comparative phenological studies of trees in tropical wet 
and dry forests in the lowlands of Costa Rica. 
J. Ecol., 62, 881-919. 

Glander, K.E., Fedigan, L.M., Fedigan, L., & Chapman, C.A. (1991). 
Field methods for capturing and measurement of three monkey 
species in Costa Rica. Folia Primatol., 57, 70-82. 

Horwich, R.H., Koontz, F., Saqui, E., Saqui, H., & Glander, K. (1993). 
A reintroduction program for the conservation of the black howler monkey in 
Belize. Endangered Species Update, 10, 1-6. 

Jones, C.B. (1980). The functions of status in the mantled 
howler monkey, Alouatta palliata Gray: Intraspecific competition for group membership in a folivorous 
Neotropical primate. Primates, 21, 389-405. 

Jones, C.B. (1982). A field manipulation of spatial relations among male mantled howler monkeys. 
Primates, 23, 130-134. 

Jones, C.B. (1994). Injury and disease of the mantled howler monkey in fragmented habitats. 
Neotropical Primates, 2, 4-5.
 
Jones, C.B. (1997). Rarity in primates: Implications for conservation. 
Mastozoologia Neotropical, 4, 35-47. 

Jones, C.B. (1999). A method to determine when active translocation of nonhuman primates is justified. 
Journal of Applied Animal Welfare Science, 2, 229-238. 

Malik, I., & Johnson, R.L. (1991). 
Trapping and conservation: Development of a translocation in India. 
In A. Ehara, T. Kimura, & M. Iwamoto 
(Eds.), Primatology today (pp. 63-64). Amsterdam: Elsevier. 

Myers, N., Mittermeier, R.A., Mittermeier, C.G., da Fonseca, G.A.B., & Kent, J. (2000). 
Biodiversity hotspots for conservation priorities. 
Nature, 403, 853-858. 

Rodriguez-Luna, E., & Cortés-Ortiz, L. (1994). Translocacion y seguimiento de un 
grupo de monos Alouatta palliata liberado en una isla (1988-1994). Neotropical Primates, 2, 1-5. 

Scott, Jr., N.J., Scott, A.F., & Malmgren, L.A. (1976). Capturing and marking howler monkeys for 
field behavioral studies. Primates, 17, 527-534. 

Correspondence to: 
Clara B. Jones, Ph.D., 
Department of Psychology, 
Livingstone College, School of Liberal Arts, 
701 W. Monroe Street, 
Salisbury, NC 28144, U.S.A.; 

Office Phone:(704)216-6059; 
E-mail:	cjones@livingstone.edu(O); 
		howler425@cs.com(H).