The owner of a flock of MN3 Wiltshire Horn sheep experienced unusually severe reactions to Gudair vaccination of his sheep. Many Market Assurance Programme (MAP) participants have elected to vaccinate their Monitored Negative (MN) sheep flocks with Gudair to protect their sheep from OJD and to secure additional Assurance Based Credit (ABC) points as a 'whole flock of approved vaccinates.'
However, District Veterinarians and others have reported unusually severe vaccine reactions to Gudair in non-Merino sheep, possibly exacerbated by vaccination against caseous lymphadenitis (CLA).
On 2nd November 2006, an experienced and accredited contractor vaccinated the whole flock with Gudair. The contractor vaccinated all sheep including the lambs in the race. The contractor gave the 2006 lambs, previously vaccinated with Glanvac subcutaneously in the axilla on 4th November 2006 a booster vaccination at the same time as the sheep were vaccinated with Gudair.
On 5th December 2006, the owners, greatly concerned by the vaccine reactions, contacted their private practitioner. They were concerned that a high proportion of the flock had reactions many of which were large with discharging abscesses, granulomatous lesions and open dry wounds. A small percentage was flystruck as shown in the photographs below. Fortunately, flies were uncommon presumably due to the drought.
On 14th December 2006 Pfizer representatives visited the property. They reassured the owner that they had observed serious reactions in the past and they usually healed.
On 1st February 2007, Ranger Richard Lelievre and I revisited the property and examined 65, August-September 2006 ewe and ram weaned lambs.
We found that:
Overall 36/65(55%) had lesions that had discharged. This is eleven times the 5 % regarded as normal in the packaging information. It is possible but unlikely that some lesions were from Glanvac.
Ram 205 with a very severe granulomatous discharging lesion seen at the visit 14.12.2007 had been euthanized for an unrelated condition. The ram's vaccine lesion was resolving when it was euthanized. Ewe 368 also photographed prior to the initial property visit with a discharging abscess was not re examined.
Ram 340 was examined 01.02.2007 and had a reaction 5.0 cm diameter behind the right ear. This ram had an injury and eye infection that appeared to have resolved before being vaccinated. Post vaccination (same side) he developed an abscess behind or above the eyeball, which had to be drained by his veterinarian. The eye was now protruding again. I examined the ram and advised the owner that I thought it unlikely that the vaccine reaction would track to behind the eye based on my understanding of lymphatic drainage in the area. I suggested that if the eye abscess was drained again the material could be submitted to a laboratory to see if oil derived from vaccine was present.
The owners reported that all classes of sheep have a low percentage of lesions that have continued discharging and that granulomatous reactions persist in some adult sheep. The owner commented that on 3 February 2007, one ewe (230), had a large, newly erupted abscess, ewe 128 is having prolonged problems and a few more vaccine sites may still be discharging.
The adverse reactions to Gudair may be breed-related. A number of District Veterinarians and others have observed a disproportionate number of severe vaccine reactions in non-merino breeds of sheep.
There has also been some speculation that Mycobacteria and Corynebacteria may share an antigenic relationship and so C.ovis antigens (in Glanvac) may sensitise sheep to Gudair (Ian Lugton, pers comm.).
Wiltshire Horns have very thick skin, shed their fleeces and have a lot of hair in the fleece. It is possible that this skin type predisposed to the adverse reactions seen.
This property previously ran poultry. If avian TB was present, could it have persisted in wild birds and cause sensitisation? This seems an unlikely explanation for lamb reactions.
This year the owners plan to vaccinate their lambs with Gudair and Glanvac concurrently. We will visit the property a month later to inspect the sheep and assess reaction to the vaccine.