Central West district vet update: September 2022

06 Sep 2022

The Central West Animal Health and Biosecurity team have been busy in the field, and delivering a range of presentations and workshops focused on raising awareness of the exotic diseases currently circulating close to our shores. We have been:

• Sharing our knowledge and expertise on the clinical signs and symptoms of foot and mouth disease and lumpy skin disease,
• Working closely with both the ag team and local Rural Crime investigators to deliver information to producers on what can be done on farm to better control feral animals, the importance of accurate and timely NLIS data and discussions around farm and biosecurity planning and the issue of illegal hunting.

Pink eye in sheep

Cases of pink eye in sheep have been recently diagnosed in our south. Pink eye causes pain and blindness in both sheep and cattle and is usually temporary, but can be permanent (more so in cattle than sheep) depending on the severity.
Some factors that cause outbreaks at this time of year are:

• Animals in close contact such as yarding, shedding or lot-feeding.
• Irritation/injury to the eye (long feed, dust), allowing the bacteria to become established.
• Mixing different mobs of animals.
• Stressful events reducing immune function.
• Flies becoming more active and spreading infection between animals.

What can be done to minimize the risk?

• Close contact can exacerbate the severity of the outbreak, therefore yarding to apply treatments needs consideration, especially with sheep. However pink eye in cattle can be more serious. Affected cattle should be monitored and brought in for treatment where the infection continues to progress.
• A vaccine is currently available for pink eye in cattle; however this needs to be given a good 6 weeks before challenge to get the best results. We would recommend you seek advice before embarking on a vaccination program this season.
• Fly traps to reduce fly populations may be of value, and application of fly prevention products may also help.
• Ensure adequate and balanced nutrition is available.
• Control internal parasites to keep your stock healthy.
• Any stressful event can lower immunity and put stock at greater risk. Using low stress stock handling principles has many benefits.

Lame sheep

As we head into yet another wet spring the incidence of lame sheep is increasing. We are seeing the full spectrum of conditions that cause lameness from scald, abscesses to benign and virulent footrot. This comes as a timely reminder to use quarantine procedures for all introduced stock. Inspect all sheep on arrival/return to your property. Investigate any lame animals and continue to monitor for at least several weeks before allowing contact with home sheep.
Your District Vet can help determine the cause of any lameness. Footrot is still notifiable in NSW, so if you are concerned then please get in touch. Also be aware that lameness is a clinical sign of foot and mouth disease in both sheep and cattle.

Bloat risk increasing

A case of bloat was recently seen in the south where a single heifer in a small mob was found dead. She was grazing a cereal crop and had access to grain and hay. While clover dominant pastures are known to cause bloat, any fresh green feed that is highly digestible poses a risk. The gently increasing spring daytime temperatures we are experiencing promote vegetative plant growth of high digestibility which will increase the current bloat risk across our region. 
It helps to know when the season is shifting and the bloat risk is increasing so that you can consider enacting or adjusting bloat prevention strategies in your cattle. A free app, called Bloat Alert, has recently been developed as part of Charles Sturt University research into bloat in southern beef production systems. Cases reported on the app will be detailed on a map (anonymous - according to postcode only), and you can set it up so that if bloat is reported in your local area you will receive a notification. Interesting technology!

Yersiniosis

Cases of Yersiniosis have recently been diagnosed in a mob of weaner cattle and weaner lambs in the Central West. Up to 40% of the weaner lamb mob were affected and mortality rates of 10% were reported. Affected animals presented with acute enteritis (inflammation of the small intestine) characterized by profuse, watery diarrhoea, abdominal discomfort, and weightloss/ill thrift.
Yersiniosis is seen in the cooler months and often associated with high rainfall. Outbreaks have been linked to periods of limited feed, worm burden or a stressful event such as weaning.  It is suggested that a complex interaction between environmental, management and animal risk factors precipitate an outbreak.

Vaccinating sheep against pulpy kidney

Various vaccine products are available for preventing common sheep diseases. Deciding which ones to use requires a consideration of the risk of the particular disease to the flock versus the cost of vaccination.
Pulpy kidney (PK) is caused by Clostridium perfringens, a bacteria of the clostridial group and is normally present in the gut. Under certain conditions it multiplies and produces a toxin which poisons the animal. It most frequently affects rapidly growing lambs, especially when they are given access to lush feed or grain. Affected animals may be found dead or dying with terminal convulsions.
Because PK is such a common disease, PK vaccine is very important. Usually the vaccine will include other clostridial disease agents (eg tetanus, blackleg, black disease). It may also include non-clostridial disease agents (eg cheesy gland). Some PK vaccines contain nutritional supplements (eg vit B12 or selenium) and one product includes a worm drench.
PK vaccines require two doses to be effective, a primary dose given at marking, then a booster 4-6 weeks later. It is ideal to give ewes an annual booster 4-6 weeks prior to lambing to ensure that lambs receive additional protective PK antibodies in the colostrum.

WHAT TO LOOK OUT FOR

• WORMS: Judging from many worm test results we are seeing, worms are going to continue to cause headaches for sheep producers into spring. At this stage of the year clean paddocks will be few and far in between - did you know that in seasons such as this it will take six months for 90% of the worm larvae population to die out on pasture?? Look after your weaners. In all cases lambs should be given an effective drench at weaning and put onto a clean paddock. It is high risk to put weaners onto a paddock that has carried lambing ewes this year.
• FLIES: They are coming to your farm very soon... start preparing and implementing your fly management strategy now!
• ANAEMIC SHEEP WITH PALE GUMS. It could be weaner anaemia (Mycoplasma ovis) or barber's pole worm. The two are easily confused as they both cause weakness and pale gums. Contact your private vet or District Vet to get a diagnosis as their management is completely different and losses could be significant if you get it wrong!
• JAPANESE ENCEPHALITIS: A mosquito born disease that causes abortions in pigs, neurological clinical signs in horses and is zoonotic, meaning it can infect people. Stock the shelves with insect repellent, cover up at dawn and dusk and get your ‘deet on’ this spring. A human vaccine is available, consult your health care professional for further human information.

WHAT TO THINK ABOUT

• Monthly worm test monitoring for sheep flocks is almost essential this year. Drop into your Local Land Services office and pick up worm test kits today!
• Pain relief strategies at lamb marking.
• Ram soundness checks for the upcoming breeding season.