Vaccination of feral pigs (Sus scrofa) using iophenoxic acid as a simulated vaccine

Abstract

Objectives To develop an encapsulation method for delivery of vaccines to feral pigs, and quantify the effect of iophenoxic acid on captive feral pig blood iodine concentrations to assist in investigation of factors affecting vaccine uptake.Design and methods Feral pigs were administered iophenoxic acid by oral gavage, and consumption was assessed for different encapsulation methods in baits. Blood iodine concentrations were monitored for eight days after consumption. The relationship between dose rate, time since dosing and blood iodine concentration was assessed for gavaged and baited captive feral pigs. Wild feral pigs were baited with PIGOUT® baits containing 20 mg of encapsulated iophenoxic acid to simulate a vaccination program. Using knowledge from the pen studies, bait uptake and factors affecting bait uptake were investigated.Results Bait‐delivered iophenoxic acid led to variable and inconsistent changes in blood iodine concentrations, in contrast to pigs receiving iophenoxic acid by gavage. This precluded accurate assessment of the quantity consumed, but still allowed a conservative determination of bait uptake. Iophenoxic acid in smaller capsules was consumed readily. Increasing baiting intensity appeared to increase bait uptake by wild feral pigs, and pigs of varying sexes, ages and weights appeared equally likely to consume baits.Conclusions Encapsulated liquids can be delivered to feral pigs within baits, should the need to vaccinate feral pigs for fertility or disease management arise. High baiting intensities may be required.

Selective piglet feeders improve age-related bait specificity and uptake rate in overabundant Eurasian wild boar populations

“…This confirmed that encapsulated liquids can be delivered to wild boar within baits, and the vaccine would eventually come to contact with the oral mucosa. Nonetheless, although eating or chewing a vaccine capsule is a primary requirement, this may not necessarily result in the actual vaccination occurring (Cowled et al 2008); this needs to be assessed under experimental and field conditions. Placing the baits inside selective feeders for wild boar piglets was found to be a much more selective method for delivering oral vaccines to wild boar because only young wild boar visited the feeders by night.…”

Specificity and success of oral-bait delivery to Eurasian wild boar in Mediterranean woodland habitats

“…Twenty milligrams of IPA per bait may be insufficient to detect bait consumption in adult animals or when they consume one bait only (Cowled et al 2008). Therefore, higher amounts of IPA (40 mg/bait) as used herein may give more reliable estimations of bait uptake (Cowled et al 2008).…”

“…Recently, Et-IPA has been used successfully to investigate wild boar baits and baiting strategies to deliver oral vaccines, contraceptives, and toxicants (Fletcher et al 1990;Mitchell 1998;Fleming et al 2000;Campbell et al 2006;Cowled et al 2008;Massei et al 2009). Et-IPA can be incorporated into baits as a chemical marker because it binds to proteins in the blood plasma and elevates the protein-bound iodine in animals that consume Et-IPA-marked baits.…”

Control and eradication of Classic Swine Fever in wild boar

“…The latter indicates that vaccination with baits before that age is probably not possible. In order to follow and study oral uptake of the baits, iophenoxic acid has been successfully used as biomarker (Cowled et al, 2008).…”