An Outbreak of Drench Gun Injuries

This quarter, as well as the usual updates and seasonal discussion, I wanted to highlight an interesting case I dealt with last year, as it involves something that tends to impact large numbers when seen.

As with many cases, this one started with a phone call from a client who wanted to discuss an outbreak of sudden deaths in their flock, and a few lumps on some sheep….

The swellings were all seen around the jawline, sometimes bursting out a thick, creamy pus and sometimes just resolving themselves, or bursting into the mouth. The ewes that had died tended to have had smaller swellings that hadn’t burst. Being in the run up to tupping, handling of the ewes had been minimal except for a mineral drench a number of weeks ago and they were being flushed on good pasture.

We bled a number to check for the particularly nasty Caseous Lymphadenitis (CLA); a bacterial disease which causes infectious abscesses of the lymph nodes both internal (causing weight loss) and external (such as the ones at the corner of the ear and base of the jaw), if these burst outwards the pus is wildly infectious to the flock, and the farm staff. Isolation and antibiotics were also used to reduce the infection in the ewes with the external swellings. Thankfully, the test came back negative but we still needed an answer!

Being linked with the University of Nottingham Vet School (who now also have an APHA contract for post mortem examinations ), it was agreed that if any more sudden deaths with facial swellings occurred we would send one in for a full and detailed post mortem examination (opting to do this at the university rather than on farm due to the risks if it was CLA and opening a lesion out on farm).

A call from the client followed a few days later ‘I’ve lost another one’, so off the carcass went to the university, and what followed surprised us all! There was no pus found in the mouth and no internal abscesses, instead just inflamed and oedematous muscle and lymph node tissue. However, the rumen was full of blood (which had clotted by the time the carcass arrived for PME). (Figure 1)