An alternative vaccine for enzootic or chlamydial abortion has been granted a special licence to allow trading on the Irish market.

CEVAC Chlamydia, supplied by Interchem, can be sourced through your veterinary practitioner.

However, MSD Animal Health, manufacturer of the Enzovax vaccine, says that supplies of its vaccine, Enzovax, are still available on the Irish market. It also says that normal supply of its vaccine should be available from mid-August.

Product characteristics

CEVAC Chlamydia must be administered at least four weeks before the start of mating. Hoggets and older ewes should be vaccinated during the four-month period prior to mating while the advice for ewe lambs intended for breeding is to vaccinate from five months of age.

The vaccine can be administered on the same day as vaccination for Toxoplasmosis (Toxovax). However, sheep which are being treated with antimicrobials and particularly tetracyclines should not receive the vaccine.

Toxovax needs to be administered at least three weeks before the start of the breeding season

The vaccine is currently available in 20 or 50 doses and costs in the region of €4 to €5 per dose including VAT. For further details on the use of this vaccine, it is advisable to consult your vet.

Enzovax also needs to be ordered through your vet and administered at least four weeks before breeding. The vaccine can also be given on the same day as Toxovax, the vaccine for toxoplasmosis which is also manufactured by MSD Animal Health. Toxovax needs to be administered at least three weeks before the start of the breeding season. Ewe lambs, where intended for breeding, may be vaccinated at five months of age while hoggets and ewes should be vaccinated in the four-month period prior to mating.

Characteristic symptoms: enzootic abortion

Enzootic abortion can cause abortion, mummified foetuses and the birth of weak lambs. It is caused by a bacterial type organism, Chlamydophila abortus, and generally is characterised by abortion in the final two to three weeks of gestation. There can be a low level of cases or an abortion storm where disease is new into the flock with upwards of 25% of sheep affected.

Ewes that suffer from the disease are unlikely to abort in later years

The disease is spread from sheep to sheep with the most likely route of entry to a flock through the purchase of replacements. The disease can spread rapidly in an unvaccinated flock from aborted material. Ewes that suffer from the disease are unlikely to abort in later years (depending on the level of prevalence in the flock) but will act as a reservoir for the disease and continue to spread it to healthy animals.

Pregnant ewes can however pick it up at lambing, the disease can remain silent for the year and the ewes can then abort at the following lambing. Culling is a control option but if the disease is present in a flock there is generally little option but to vaccinate. This also raises the importance of purchasing replacements from known sources.