Are Anthelminthic Treatments of Captive Ruminants Necessary?

Liron Lahat,Paolo Tizzani,Francisco Valera,Rocío Ruiz De Ybáñez,Eulalia Moreno,Belén Ibáñez,Juana M Ortiz,Gerardo Espeso

doi:10.3390/vetsci8100240

Abstract

Anthelmintics are frequently administered to animals to limit fecal egg elimination, so that wild animals in captive breeding programs are treated to maintain a proper health condition. This is effective from a health management perspective, but on the other hand, it could prevent captive animals from developing an effective immunity against parasites that they might encounter when reintroduced into their original geographic areas. The aim of this study was to describe the dynamics of parasite infections in captive Cuvier’s gazelles (Gazella cuvieri) not treated with anthelmintics for two years and to evaluate the factors related to their fecal egg shedding. Fifteen one-year-old males were enclosed together and captured monthly to collect feces directly from the rectum. Fecal egg counts were performed, and eggs were classified as strongylid-like, Nematodirus sp., or Trichuris sp. Fecal egg shedding for the three groups of parasites did not vary significantly over the duration of the study. Only precipitation affected the egg-shedding pattern of all parasites, while inbreeding was positively associated with the number of strongylid-like parasites. These findings suggest an equilibrium between hosts and parasites in absence of treatment during the study. The anthelmintic treatment as a systematic prophylaxis method in captive animals should be avoided and replaced by systematic coprological and clinical vigilance, as well as targeted treatment in the case of a significant rise of fecal egg counts.

Highlights

Reintroduction programs of endangered species using captive-bred individuals from zoological institutions have been a well-established conservation tool for many years, successful for mammals [1,2]
There is an ongoing discussion to assess how zoos can contribute in the most effective way to species conservation [4,5], and a proper animal health management within captive breeding programs [6] is a key issue in such a debate
The constant presence of parasites may be due to (i) continuous infection from the contaminated environment [8,31] and (ii) the hypobiosis phenomenon described for some gastrointestinal nematode species such as O. ostertagi and C. mentulatus [21,22,23,24]

Summary

Introduction

Reintroduction programs of endangered species using captive-bred individuals from zoological institutions have been a well-established conservation tool for many years, successful for mammals [1,2]. There is an ongoing discussion to assess how zoos can contribute in the most effective way to species conservation [4,5], and a proper animal health management within captive breeding programs [6] is a key issue in such a debate. Anthelmintic drugs are a common tool for parasitic diseases treatment and prophylaxis in zoos [1], and their use was referred to in the guidelines proposed for wildlife prior to translocation and release [7]. In captivity, it is useful only for a short period of time, and animals become reinfected shortly after the interruption of the therapy. Most captive animals harbor a diverse parasite community, and anthelmintic treatments are used only to control and not to eliminate parasitic infections

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