WA Livestock Disease Outlook - for producers

Recent livestock diseases

Lupinosis detected in Wheatbelt sheep

• Six of 1500 merino wether lambs died on a property in December, with a further 800 animals affected. The affected sheep appeared lethargic and had been losing condition. 
• Sheep were recently purchased from a Wheatbelt property and had been grazing a lupin stubble for the past 6-8 weeks.
• Two lambs showed neurological signs including facial twitching and apparent blindness. The lambs were lying down and had difficulty rising.
• The producer contacted their private vet to conduct a disease investigation and received a subsidy through the Significant Disease Investigation Program.
• Always contact a vet if you see unusual signs in livestock. Producers can access a variety of subsidies for disease investigations in livestock. These subsidies are designed to support Western Australia’s market access and food safety. For more information speak to your vet or visit the surveillance incentives webpage.
• The private vet examined the sheep, conducted a post-mortem and submitted samples to DPIRD for testing.
• Testing of the liver confirmed a diagnosis of lupinosis, which causes severe liver damage. Loss of liver function leads to a condition of impaired brain function known as hepatic encephalopathy.
• Blood results showed that both animals also had a vitamin E deficiency.
• Testing also ruled out lead toxicity, which could also cause blindness and lethargy in sheep (and cows), and is a risk to human food safety and access to export markets if found in food-producing animals.
• Lupinosis is a liver disease caused by the consumption of lupin stubble colonised by the fungus Diaporthe toxica (previously called Phomopsis leptostromiformis). It can be expressed in either an acute form or a chronic liver dysfunction syndrome. The acute form is most likely to occur after summer rains where the lupin stalk becomes softened and more palatable to livestock. All livestock are susceptible to lupinosis but sheep are the most susceptible. Weaners are most commonly affected because they tend to eat the stem of the lupin. 
• Vitamin E deficiency is widespread in weaner sheep flocks in WA over the long, dry summer-autumn period when green feed is scarce. Signs of vitamin E deficiency in sheep include weaner illthrift, reduced wool production, reduced ewe fertility, reduced immune response and damage to the muscles resulting in lameness and weakness.
• Read more about lupinosis in sheep and vitamin E deficiency in sheep.

Cow with skin growths tests negative for exotic disease

• A private vet examined a 2-year-old cow with skin growths covering the face and neck.
• The vet suspected warts due to bovine papillomavirus but wanted to rule out the exotic disease lumpy skin disease, which can cause similar signs. Samples were submitted to DPIRD and the submission was exempt from laboratory fees because a reportable disease was excluded.
• One cow from a group of 30 was affected (Figure 1).
• Lab testing confirmed cutaneous papillomas (warts) due to bovine papillomavirus and ruled out the exotic reportable disease lumpy skin disease. 
• Warts in cattle can be caused by bovine papillomavirus. They commonly occur on the skin of young animals between 6 and 24 months of age. Usually the warts go away spontaneously as the cattle develop immunity to the virus but may persist for up to 12 months in some animals, especially animals that are immunocompromised.
• Bovine papillomavirus can be transmitted between cattle directly, or via contaminated surfaces such as water troughs and fence posts.
• The negative result for lumpy skin disease in this case helps to support WA’s market access by demonstrating freedom from the disease.
• Lumpy skin disease is a highly infectious disease of cattle. It is mostly transmitted by biting insects.
• Lumpy skin disease is exotic to Australia. The international distribution of lumpy skin disease is increasing in range, and it would have a significant impact on cattle productivity if it entered Australia. Disease signs include lumps on the skin, fever, salivation and nasal discharge. If you see any unusual signs in livestock, you should always contact a vet.
• Read more about lumpy skin disease in Emergency Animal Disease Bulletin No. 121

Figure 1. Cow with skin growths on the head

In summer, watch for these diseases:

Slender iceplant poisoning in sheep

• Slender iceplant is a small, succulent, winter-growing annual weed that is most common in the eastern Wheatbelt. When the plant is dead and dry in summer, it contains high levels of sodium which attracts sheep, and also contains high levels of oxalate which can poison sheep. Poisoning occurs from October to April and the plant is most toxic when it is dead.
• Oxalate poisoning results in a calcium deficiency and kidney failure in sheep, and signs in affected animals include weakness, collapse, tremors, nasal discharge, muscle paralysis and sudden death.
• Producers who have sheep with nervous signs (such as muscle paralysis, staggering and tremors) investigated and autopsied by a vet may be eligible for TSE subsidies to cover all the laboratory costs and most of the veterinary autopsy and travel costs. Speak to your vet to find out about surveillance incentives for producers.
• To prevent iceplant poisoning, provide sheep with good quality hay when put into paddocks at risk of slender iceplant contamination. Provide sheep with a limestone and salt loose mix or a block in a container with drainage holes before and during grazing of paddocks at risk of iceplant contamination.  
• Read more about slender iceplant poisoning.

Vitamin E deficiency              

• Usually widespread in weaner sheep during the long, dry summer-autumn period, or feedlot animals. Sheep may be weak, lame, in poor condition or they may die suddenly when driven.
• Lameness can occur with reportable diseases footrot and foot-and-mouth disease, so always have a vet investigate lameness in sheep to determine the cause.
• Body stores of vitamin E decline on any dry feed, however the decline can be more rapid on high grain diets.
• A 2000mg/sheep vitamin E drench can treat deficient sheep for six weeks. Severely affected sheep may require a repeat dose 2–3 weeks later.
• Vitamin E deficiency is rapidly resolved with access to green feed.
• Read more about prevention and treatment of vitamin E deficiency in sheep.

Grain poisoning in livestock

• Consumption of large amounts of grain without gradual introduction can result in grain overload (also called acidosis or grain poisoning).
• Signs in affected animals include bloating, staggering gait, lameness, diarrhoea, depressed appearance, lying down, dehydration and thirst, and death.
• You should always contact your vet if you see these signs in your livestock. Lameness can also occur with some reportable diseases. Subsidies may be available under a number of surveillance incentives for producers for a veterinary investigation and laboratory testing.
• Grain should always be introduced gradually so that the rumen (first stomach) has time to adapt to the change in diet. Good quality roughage (hay) should also be provided. 
• More information on grain poisoning in livestock including ways to prevent grain poisoning.

DPIRD disease investigation summary 2020

In 2020, the Department of Primary Industries and Regional Development investigated 1402 cases of disease in animals, primarily livestock.

Submissions were received from 77 private vet services and also government vets.

Data from disease investigations provides evidence that WA is free from reportable diseases and supports our continuing access to markets. It is always worth calling a vet to investigate disease in your livestock. 

The exotic disease ehrlichiosis (E.canis) was detected in dogs in the state’s north for the first time in 2020. Vets submitted 513 potential cases of ehrlichiosis to the department for investigation of which 202 were positive for the disease.  E.canis is a bacterial disease spread by the brown dog tick.  Infections with E.canis are limited to dogs living or visiting the range of this tick which is common in the tropics and subtropics but is unknown below Latitude 23° South.

Reportable disease exclusions

During 2020, there were 1056 reportable disease exclusions from 570 submissions to the laboratory. A disease exclusion means a disease is tested for and not detected. The most common reportable disease exclusions are shown in Figure 2.  (This chart does not include E.canis testing.)

Figure 2. The top 10 reportable disease exclusions from laboratory submissions to DPIRD laboratory from January – December 2020. The orange bars represent the number of reportable disease exclusions from October – December 2020.

Common diseases in sheep and cattle in WA

Commonly diagnosed diseases in cattle and sheep in October – December 2020 are shown in the table below. The most commonly diagnosed disease in cattle was annual ryegrass toxicity (ARGT). The most commonly diagnosed disease in sheep was gastrointestinal worms (helminthiasis).