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Programmes to Eradicate Mange


Reprinted from PIG INTERNATIONAL

A recent issue of Pig International (September 1999) contained specialists' comments about monitoring sarcoptic mange infestations in pig herds. The authors also had provided remarks which could not be included for reasons of space, concerning the eradication of mange mites from an infested herd.
Here are some edited abstracts from those remarks.

Mange mites can be eradicated from a herd either by depopulation/repopulation or by medication. The first of these is relatively expensive and demands that mange-free animals are available for the re-stocking.
From an economic viewpoint, mange alone can hardly justify using this method.

Thousands of herds in many countries are now mange-free due to a program of eradication by medication, in which ivermectin is injected twice with an interval of 14 days. In the very few occasions where mites were not eradicated, often the reason was a failure to maintain the barrier between treated and nontreated pigs. Various intervals have been used, from 10 to 28 days, dictated in most cases by the locally approved withholding period. From results of different trials, a special interval cannot be emphasised, but it is important that all animals in the herd be treated at the right dose and at the same time.

No difference in success rates has been found for eradications done in different seasons of the year.
Mites and mite eggs survive longer in a cold, humid environment, but most mites will die within the first 1-2 days off the host, and the maximum survival time is considered to be 10-12 days.

Because the whole herd is treated, the amount of acaricide for an eradication program is approximately 1.5-3 times that used during a year for continuous treatment. The amount of labour required by eradication varies, but has been shown to average about 15 hours per 100 sows.

The protocol for eradication in the Netherlands, so that a herd can be certified for absence of mange mites by the Dutch Animal Health Services, calls for all pigs on the farm to be injected with ivermectin on Day 0 and Day 14. Any piglets born after Day 0 and up to Day 7 must receive an ivermectin injection on Day 7.

Researchers in Belgium used a combination of ivermectin injection and in-feed for a closed breeding herd. Sows, boars and piglets were treated by subcutaneous injection on Days 0 and 14, while growers and finishers were given the oral powder in-feed for 2 periods of 7 days, with an interval of one week between. Feed dosages were 2ppm for 25-40kg pigs and 2.4ppm for those in the 40-100kg weight range.

A programme implemented in Denmark used feed medication for a total of 16 days. The medication was given to every gilt, sow, boar, weaner, grower and finishing pig at a level to ensure a dose of 100mcg ivermectin per kilogram of bodyweight per day. On Days 0 and 14, all piglets were injected at a dose rate of 300mcg/kg. An equivalent injection was given on Day 7 to piglets born between Days 0-7, and to all animals in the medicated feed group where feed intake was inadequate.

In Germany, an eradication scheme involved whole-herd treatment with IVOMEC Premix (100mcg ivermectin/kg) for 14 consecutive days, mixed in the six feed mixtures used on the farm. Sows which farrowed during the treatment period, piglets just weaned, and suckling piglets received IVOMEC Injection (300mcg ivermectin/kg). Animals that would otherwise have been treated with IVOMEC Premix but showed loss of appetite for at least 2 days, received treatment with IVOMEC Injection.

The limited experiences with combined feed/injection programmes, until now, leave the impression that their success rate is at a similar high level to that resulting from two injections of ivermectin. The uncertainty of the dose in feed medication does not seem to influence the safety and efficacy of these programmes. There is a variation in the period of treatment with IVOMEC Premix from 14 to 21 days, and some of the successful eradication schemes have a 7-day interval between two treatment periods of 7 days.

Dr. T. J. Ebbesen Dr. T. J. Ebbesen is a veterinarian with Danish Bacon & Meat Council in Denmark
 

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