Mortality in lambing ewes
With lambing either under way or about to start on many Central Tablelands properties, our district vet team is seeing the usual causes of ewe mortalities.

Aside from pregnancy toxaemia, lambing difficulties and cast ewes some producers report the strange condition, spontaneous vaginal rupture. This problem occurs in large crossbred or composite ewes in the couple of weeks before lambing. In big heavy ewes, often in above average condition and usually bearing at least twins, the intestines rupture out, leading to rapid death.  

This condition and several others (such as vaginal prolapse and foot abscess) are more likely in ewes in fat scores 4 and 5. However twin bearing ewes need to be well fed to support twin foetuses and to milk well. This dilemma reflects the challenge of managing a high-performance ewe flock. 

Abortion in sheep

Occasionally, scanning can also detect unusual findings that might indicate an ewe has recently lost a pregnancy or is showing signs of an unhealthy foetus or placenta that will likely be resorbed or expelled. Our district vets recently investigated a case where ~10% of ewes were reported by the scanner to be displaying such changes. Several foetuses were aborted whilst the ewes were yarded for scanning and these were collected for further assessment.

Producers are always encouraged to pick up aborted foetuses, place them in a plastic bag and store them in the fridge before immediately contacting their district vet or private practitioner. Even incomplete and decomposing specimens can be of value.

A recent review of ovine abortion cases indicated that the likelihood of getting a diagnosis is more than doubled by the inclusion of placenta so membranes should also be collected when available. Producers should always wear protective clothing and gloves and thoroughly wash their hands in soapy water after handling aborted material as some pathogens are transmissible to people.  

Laboratory analysis of foetal samples collected during this recent incident diagnosed Listeria ivanovii as the cause of abortion. This disease is usually acquired by ewes ingesting feed contaminated with the bacteria. Listeria species may be found in spoiled silage, decomposing hay or rotting vegetation. Cases are often seen after periods of cold, wet weather.  

This case highlights the importance of early investigation of unusual findings so prompt action can be taken. Our district vets elected to commence antibiotic treatment of these ewes in an effort to prevent additional losses. 

Barber's pole worm
Over the last month, our district vet team has diagnosed several cases of severe barber’s pole worm infestation. Although winter is generally thought to be a lower risk time for barber’s pole in the Central Tablelands, the colder conditions actually prolong larval survival on pasture. The colder weather does stop any worm eggs deposited on the ground from hatching.  

Barber’s pole worm is easily diagnosed during a postmortem as the worms are visible in the abomasum (4th stomach). In two cases a worm egg count was performed on faecal samples taken during postmortem. One case had a count of 22,800 eggs per gram, the other had a count of over 120,000 eggs per gram. For those not familiar with egg counts, district vets start getting nervous at around 800 eggs per gram, sometimes less, sometimes more, depending on the situation.  

Signs of barber's pole worm include pale mucous membranes (most easily observed around the eye), and a “bottle jaw” appearance in severe cases. Production losses occur long before these signs are visible, so regular worm egg counts are a must, even over winter. 

• Senior District Vet Bruce Watt shares his insights into grass tetany
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• Predicting likelihood in cattle
• Treatment and prevention