Animal Health April Update 🐄🐏

Riverina producers often call to discuss results of Abattoir meat inspection reports (MIR), where they receive a notification for carcass condemnation or trimming due to various conditions. Recently, producers have been querying what ‘TENUI’, ‘HYDATIDS’ and ‘OVIS’ mean, why they are consistently seeing sheep and goats affected on meat inspection reports and how they go about preventing it.

Below are examples of recent Abattoir processing reports from Riverina producers. Both producers have working and/or hunting dogs on their property.

All the conditions listed above are caused by a species of tapeworm, all of which require a dog to complete their lifecycle.

In previous newsletters, we have shown results from the National Sheep Health Monitoring Program, which commenced in 2007 to monitor lines of sheep in abattoirs for animal health conditions that reduce farm profit through productivity losses or increase meat processing wastage. Bladder worm and sheep measles are consistently reported as being the most common and widespread condition reported in lamb and mutton sold over the hooks from producers in the Riverina. Whilst hydatids are reported in far fewer cases, they are often alongside bladder worm and sheep measles as the mode of transmission is the same.

Clinical expression
Clinically, these tapeworms have very little to no effects on sheep, goats or dogs health, therefore are very difficult to detect if they are infected.

Post-mortem
When sheep and goats are slaughtered, these tapeworms are easy to detect.

Sheep Measles: Small (2-10mm) firm white/cream-yellow cysts found in muscles of sheep (including the heart)
Bladder Worm: Fluid filled (up to 60mm) sacs (or ‘bladders’) found attached via a long thin neck to organs within the abdominal cavity (e.g., liver).
Hydatids: Larger firm white/cream cysts, which range in size, found in the lungs, liver and other organs.

NOTE: Each of these cysts contain one tapeworm larvae.

Sheep Measles Bladder Worm Hydatids
Images provided from Animal Health Australia (AHA)

What does this mean?

These species of adult tapeworms are found in the intestines of dogs, which produce eggs that are passed in faces onto pasture. When sheep or goats graze infected pasture, eggs are ingested, then hatch within the intestines and migrate around the body to form cysts in organs. Dogs become infected by ingesting sheep and goat organs that are infected with these cysts. It takes just over a month for the dog to become ineffective after they ingest tapeworm cysts (range 32-80 days, as it varies between tapeworm species).

Image provided from Animal Health Australia (AHA).

As tapeworms typically have no clinical effects on sheep and goats, on farm losses are rare. Their significance lies in the costs incurred from trimming (which reduces carcass weight) and condemnation of sheep and goat carcasses at abattoirs.

Keep in mind that hydatids (Echinococcus granulosus) are zoonotic. People can become infected by ingesting the eggs within dog faeces, but NOT by eating cysts in infected meat or offal.

What can be done to prevent?

There is no treatment for sheep measles, hydatids or bladder worm in sheep and goats. Even if the larvae within cysts become non-viable, the cysts remain within sheep and goats for their entire life. Prevention lies in breaking the tapeworm life cycle by either 1) preventing dogs from eating ineffective larvae/cysts in meat or offal OR 2) if they become infected, ensuring they are treated before they can produce eggs.

Worm your dogs monthly with a wormer that contains the active ingredient Praziquantel. Ensure dogs are dosed according to weight and round the dose up to the nearest tablet or half tablet.
Ensure any dogs that come onto your property (e.g., contractors, family pets or hunters) are treated within 3-30 days prior to arrival.
Do not feed raw sheep or goat meat/offal to dogs. Feed your dog approval commercial dog food or, if you prefer to feed meat, ensure it is thoroughly cooked or frozen for 2-weeks at 10°C.
Burn or bury sheep and goat carcasses regularly to prevent scavenging.
Prevent dogs from scavenging by keeping them contained when they are not working.

NOTE: Wild dogs can contribute to wildlife cycles of infection, and so too can foxes but to a far lesser extent (more so for Hydatids). Ensure you have a pest animal management plan in place. Contact your local LLS Biosecurity Officer for advice.

After you initiate these prevention strategies, it is common to see these conditions on abattoir processing reports for some time. This is because 1) tapeworm eggs can remain on the pasture for up to a year; and 2) scarred remnant of cysts remains in livestock for life. Time and persistence with these strategies are key to ensuring economic losses are minimised.

If you are interested in understanding more about the different conditions that impact carcass quality, check out the link below or contact your local LLS District Veterinarian.

For more information:
Sheep Health Conditions – Carcass Impacts (sheepcarcassconditions.web.app)

With autumn lambing well underway, we have had numerous calls regarding down ewes during late term pregnancy caused by hypocalcaemia (milk fever) or pregnancy toxaemia (lambing sickness), often at the same time.

Pregnancy toxaemia occurs as the energy requirements of late-pregnant twin-bearing ewes is as high as 18MJ/day – often they can’t physically eat enough to meet these requirements. To compensate for this energy deficit, fat is mobilised and converted to glucose in the liver – over time this process can overwhelm the liver and cause ewes to go down. Hypocalcaemia is a result of low blood calcium, which is involved in muscle contractions. Hypocalcaemia occurs when the calcium demand of pregnant and lactating ewes increases at times when uptake is low (e.g., grain diets, green pick and inappetence). In cases seen, both diseases were triggered by a combination of either a stressful event (e.g., crutching, mustering), extended time off feed, over-fat ewes (BCS >3.5) and inadequate feed on offer.

Clinical Signs

Later signs ewe present with nervous signs

Treatment

4 in 1 injection e.g. Flopak Plus or Minbal – 100mL morning and night administered under the skin.
Propylene glycol drench e.g., Ketol – 125mL daily until recovered or Ceton – 50mL morning and night.
Rehydration solution e.g. Vytrate – 160mL undiluted every 4-6 hours as required.
Sternal recumbency – avoid having ewes on their side. Ideally provide soft bedding (e.g. straw) and/or help the ewe to stand regularly to prevent muscle and nerve damage caused by prolonged recumbency.
Access to water and high-quality feed (grain and good quality hay)
Shelter from rain and wind

The earlier you treat, the better the outcome. Once cases proceed to recumbency >24-48 hours the prognosis is poor and humane euthanasia may be warranted.

PREPARING EWES FOR LAMBING
As some of our Autumn lambers have been reminded, losses can stack up around lambing time. Pregnancy puts strain on ewes as her resources are diverted to her growing foetus(es) and later, milk production. Her nutritional requirements increase, and she is more susceptible to succumbing to stress (e.g., moving or handling). She eats less due to the size of the growing foetus and her immunity declines, becoming more prone to worm burdens and other diseases. Ewes under nutritional stress or disease burden will have lower conception rates for the following season and produce less milk – resulting in lighter lambs that fail to thrive or die. So, if you are a spring lambing producer – heed the warning from your Autumn lambing neighbours and make sure you and your ewes are ready.
Below is a checklist on some considerations to best set up your ewes for lambing.

Book in a scan

Pregnancy scanning is an invaluable tool. It provides data on pregnancy rate (ewes pregnant) as well as reproductive rate (number foetuses per ewe). Use this information for benchmarking, early detection of reproductive problems and to identify and segregate your single and twin bearing ewes to better manage their nutritional requirements. Scanning performed 6 weeks after the end of joining allows for single- and multiple- bearing ewes to be identified.

Healthy Ewe = Happy You – BCS and Feed Budgeting

The goal for producers is to maintain your ewes’ body condition score (BCS) during pregnancy. The aim is BCS 2.5-3/5. Sudden weight loss during pregnancy will negatively impact lamb birthweights and survivability. Overfat ewes won’t be any good to you either, increasing the risk of lambing trouble (dystocia) or even pregnancy toxaemia.
A good first step is to budget your feed – starting with a look at your pastures. Grab a pasture ruler and measure what’s in the paddock. Ewes with single foetus pregnancy require 1000+ kg dry matter per hectare and those carrying twins require 1600+ kg DM/ha. Supplementation is often required, particularly in the last trimester when nutritional demands are highest.
Another good tip is to draft off ewes of BCS 2.5 or lower, and those carrying multiple foetuses, and prioritising their nutrition from day 90 of pregnancy.

Vaccination

Immunise ewes pre-lambing (ideally at crutching) – 5-in-1 clostridial vaccination as a minimum +/- Erysipelas (bacterial arthritis) +/- Cheesy Gland protection – depending on what is endemic on your property. Vaccination pre-lambing will not only boost the ewe’s immunity but it will also transfer to the lamb in the form of maternal antibodies and protect them too until they are old enough for their first vaccine at marking.

Minerals

Ewe mineral requirements increase dramatically pre-lambing. Important macro minerals include calcium and magnesium – which can be supplemented with salt in a loose-lick or mineral block. You can even make up your own with 40% salt, 40% lime and 20% causmag. Give ad lib throughout pregnancy and lactation as a minimum.
Micro- or trace minerals are also important – although there are few reports of deficiency in this area. Important types include zinc, manganese, copper, selenium, cobalt, iodine and chromium. These can be supplemented in the form of licks or blocks (45+ days to absorb) or injections such as Multimin (24 hrs to absorb).

Worms

Producers should consider a ‘strategic drench’ pre-lambing. Ewe immunity to worm burdens ‘relaxes’ a few weeks prior to- and a few months post-lambing. This means that worm burdens can establish and contaminate lambing paddocks. Worm burdens in pregnant or lambing ewes can result in malnutrition, poorer resilience against disease, and this can flow on to cause lighter and less robust lambs
Use an effective drench pre-lambing. We want a reduction of 98% or more in the worm egg count. An oral, combination, short acting drench is preferred over injectable, single-active, long-acting drench. The latter drench types have been shown to hasten resistance of worms. It is also a good idea to ensure you drench the lambs from your ewes with different actives (at weaning), to again reduce of pace of development of resistance.

Prepare the lambing paddock

Ewes should be moved to a 'safe' pasture post-drenching – i.e., a paddock that has been spelled. The two key factors that contribute to reducing worm numbers on your pasture is time and temperature.

	Maximum Temperature	Time for 90% of Larvae to die
Cold	<15°C	4 months
Warm	22°C	3 months
Hot	35°C	1.5 months
Very Hot	> 40°C	1-2 weeks

Table 1: Conditions required to achieve 90% desiccation in ineffective barber’s pole worm larvae. Source: Wormboss
Options: crop paddocks, rotate with cattle

If you’re running an intensive system and spelling pastures isn’t always an option - keep in mind that most worm larvae are typically found 1cm below the ground surface up and 5cm up sward. So larval intake can be minimised by grazing pasture >7cm.

Paddock shelter (e.g., wind break, shade) is another important consideration – to avoid hypo- or hypothermia should weather extremes occur during or around lambing time.

Size (of flocks) matters

Keep the mob size small, if possible. This avoids confusion and mismothering and has been found to increase lamb marking percentages.

Flock Size Guide:
Twins	Singles
Merino - <100 ewes X-bred - <150 ewes	Merino - <250 ewes X-bred - <300 ewes

A little privacy, please

The ewe and lamb need around 6 hours to bond, attach and imprint – so give them a little bit of space during this time to minimise mismothering and losses. If supplementary feeding, increasing the number of feeding sites can help minimise interruptions (e.g., self-feeders: 1/ 40 for twin bearing ewes, 1/60-80 for single ewes). Checking on ewes or filling up feeders mid-afternoon is typically less disruptive.

By Aimee Owens, CSU Final year Veterinary Science

While the autumn break comes with an influx of new green feed, there is potential for livestock to experience toxicities associated with grazing of these pastures. The following article discusses two toxicities commonly seen in sheep and cattle grazing certain pastures in autumn and early winter, along with potential ways to mitigate risk.

Nitrate and nitrite poisoning
Nitrate and nitrite poisoning occurs when livestock consume feeds containing high levels of nitrate, often after lush growth because of rain. Sheep and cattle are generally able to metabolise nitrates within the diet, and therefore toxicity occurs when they consume much larger amounts than normal without a period of adaptation.
High levels of nitrates may be found in lush green feeds including cereal crops and immature grasses, and weeds such as marshmallow and capeweed.

Nitrate poisoning generally causes less clinical signs and is associated with salivation, abdominal pain, and diarrhoea due to the caustic nature of nitrate on the gastrointestinal tract.
In contrast, nitrite poisoning occurs when nitrate consumed by the animal is converted to nitrite within the gastrointestinal tract and then interferes with the blood’s ability to carry oxygen. Stock die from nitrite poisoning due to a lack of oxygen (hypoxia) and clinical signs are related to this, including

Nitrate and nitrite poisoning generally affects cattle moreso than sheep, however both species are susceptible.

Phalaris toxicity
Grazing of phalaris is known to cause 2 syndromes: sudden-death and staggers; these are related to the presence of a toxic alkaloid within the plant.

Syndrome	Sudden death		Staggers
Syndrome	Polioencephalomalacia-like	Cardiac
Risk period	Autumn to early winter
Time from consumption to development of clinical signs	12-36hrs	>24hrs	>10 days to 5 months
Clinical signs	Staggering Aimless wandering Blindness Convulsion Sudden death	Respiratory distress (blue mucous membranes Death Often induced by stock movement	Tremors Head nodding Bunny hopping Walking on the knees or knuckling at the fetlocks. Cattle: tongue may be affected and ability to eat is reduced Clinical signs often occur only when animals are disturbed

Management of affected stock
If you suspect toxicities from the above causes:

Immediately remove stock the suspect pasture
Handle stock as quietly and minimally as possible to avoid exacerbating clinical signs
Provide high-quality hay to dilute toxins within the rumen.
Contact your veterinarian if you suspect any poisoning in stock.
Methylene blue is no longer approved for treatment of nitrite poisoning by the Australian Pesticides and Veterinary Medicines Authority (APVMA) for use in food-producing animals. Your veterinarian will be able to assist you regarding possible treatment options for affected stock.

Reducing risk of toxicities caused by nitrate/nitrite and Phalaris

Do not graze hungry stock on new pastures – provide roughage prior to introducing stock to these pastures to reduce initial intake or graze on safe pasture first
Control weed populations, especially in holding paddocks where weeds high in nitrate are likely to accumulate
Analyse feeds for nitrate levels if in doubt – hays, silages and drought-stressed forages can also accumulate nitrate
Observe stock when grazing on risky pastures
Avoid grazing high-nitrate pastures for 7 days after rainfall, cloudy days or temperatures causing wilting
Restricting access to Phalaris paddocks until 6 weeks after the autumn break, and/or restricting grazing to a few hours at a time
Evidence shows that providing oral cobalt can reduce risk of Phalaris staggers but does not prevent sudden death syndromes. Cobalt can be provided in the form of intra-ruminal pellets, pasture spraying, salt licks, or feed and water additives. Contact your veterinarian if this is an avenue you would be interested in exploring for your stock.

For further information, see the below documents and contact your local District Veterinarian:
Nitrate and nitrite poisoning in livestock
Phalaris staggers

The following information describes the most prevalent conditions and diseases found in sheep sold over the hook across the Riverina region in Quarter 4 (October-December) 2022. Information is courtesy of the National Sheep Health Monitoring Project (NSHMP). The NSHMP commenced in 2007 to monitor lines of sheep in abattoirs for animal health conditions that reduce farm profit through productivity losses or increase meat processing wastage. For more information about the NSHMP visit National Sheep Health Monitoring Project - Animal Health Australia

District Dashboard

What we've seen...

Wooden Tongue (Actinobacillosis)

Pregnancy Toxaemia

What we're looking out for...

Nitrate and nitrite poisoning

Worm monitoring

Case Study: ‘Is your dog costing you dollars?’

Meat Inspection Report (MIR):

Diagnosis:

Announcements

MANAGING THE DOWN EWE

Green pastures…dead stock?

National Sheep Health Monitoring Quarterly Reports Q4 2022

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