With the death of two adult female giraffe attributed to haemonchosis, endoparasitism has been identified as a significant problem in the semi-free ranging captive giraffe herd at Lion Country Safari in south Florida. Lack of a winter freeze and inability to rotate pastures contribute to pasture contamination with Haemonchus contortus larvae. In addition, larval development assays have shown varying resistance to three groups of anthelmintics (benzimidazoles, macrocyclic lactones and cholinergic agonists), making deworming less effective.1
Intensive monthly monitoring of individual giraffes’ fecal egg counts interpreted in light of pregnancy or other health status allows for deworming only when necessary. This helps establish a refugia population of endoparasites, which will be more susceptible to dewormers in the future.1,3 In addition, voluntary blood draws using operant conditioning are possible in certain giraffe. Haemonchosis can be better characterized by correlating packed cell volume (PCV) and serum protein (SP) with fecal egg counts. Judicious use of dewormers based on accurate weights alternated with copper oxide wire particles (COWP, Copasure®, Animax Ltd., Columbus, OH, USA) also has helped assuage the problem.2
Environmental control is another important aspect of the integrated parasite management program. Pasture decontamination methods such as vacuuming fecal pellets, grazing pastures with non-susceptible (non-ruminant) species such as zebra (Equus burchelli), killing grass in certain areas, and removing giraffe shedding high numbers of eggs from pasture help reduce field contamination.1 Excess grazing behavior was recognized as a risk factor for infection with H. contortus. Thus, behavior modification through the use of browse feeders has helped reduce grazing and subsequent parasite load.
Potential future methods of control of H. contortus include offering giraffe a high condensed tannin legume such as Sericea lespedeza hay and feeding them nematophagous fungi.1 Although H. contortus will never be eradicated, our goal is to manage the H. contortus worm population much as we manage the rest of our herds.
The authors thank Colleen Clabbers, RVT, Sarah Kaufhold, Terry Wolf, and the wildlife staff at Lion Country Safari for their dedication to the giraffe.
1. Fleming, S.A., T. Craig, R.M. Kaplan, J.E. Miller, C. Navarre, and M. Rings. 2006. Anthelmintic resistance of gastrointestinal parasites in small ruminants. J. Vet. Intern. Med. 20:435–444.
2. Kinney, A., M.S. Burton, J.E. Miller, J.H. Olsen, R.L. Ball, and G. Dumonceaux. 2007. Effect of copper oxide wire particles for controlling the parasitic nematode Haemonchus spp. in giraffe (Giraffa camelopardalis). 2007. Proc. Am. Assoc. Zoo Vet. Annu. Meet. Pp. 101.
3. Soulsby, L. 2007. New concepts in strongyle control and anthelmintic resistance: the role of refugia. Vet. J. 174:6–7.