RETROSPECTIVE ANALYSIS OF FREQUENT, LOW-DOSE COPPER OXIDE WIRE PARTICLE TREATMENTS, FED AS A TOP DRESSING, ON GASTROINTESTINAL TRICHOSTRONGYLOID NEMATODE FECAL EGG COUNTS IN SABLE (HIPPOTRAGUS NIGER) AND GEMSBOK (ORYX GAZELLA).

Abstract

Nematodes of the superfamily Trichostrongyloidea, particularly abomasal species, have severe clinical implications associated with high morbidity and potential mortality of exotic ruminants housed in zoological institutions. The life cycle and ecology of Trichostrongyloid gastrointestinal nematodes (TGN) present challenges in their control including development of anthelmintic resistance and reinfection in high-density managed herds. Copper oxide wire particles (COWP) are used to help control TGN infections in ruminants, administered as a bolus or a feed additive. This study investigated the effects of frequent, low-dose administration of COWP fed as a top dressing on strongyle fecal egg counts (FEC) in gemsbok (Oryx gazella) and sable antelope (Hippotragus niger). Six years of FEC data (n = 33), obtained using a modified McMaster fecal flotation, were analyzed from individuals at Fossil Rim Wildlife Center, treated exclusively with commercially available COWP in a topdressing application dosed at 25 mg/kg every 30-60 days. COWP decreased FEC in both species by a mean FEC reduction ratio of 45%, a statistically significant difference (p < 0.05) using a one-tailed paired t-test log-stabilized to minimize variance; no clinically negative effects, including copper toxicity, were observed. COWP were more effective at reducing FEC in individuals with pre-treatment FEC greater than 1000 eggs/g of feces, a statistically significant difference (p < 0.05). We conclude that frequent, low dose, top dressing application of COWP is effective at reducing FEC in sable and gemsbok, but COWP should not serve as a stand-alone method or to treat clinically affected exotic ruminants.