WA Livestock Disease Outlook - for vets

Recent livestock disease investigation

Foot-and-mouth disease ruled out in steers in the South-West

• Six out of 30 steers presented at a feedlot with salivation and mouth lesions. Another 20 steers arrived during the day from the same property of origin and ten of them were also salivating. On further inspection it was determined that half of the steers (25/50) had oral lesions.
• The steers had been purchased from a saleyard the day before, and there was no note of any unusual signs when the steers were loaded for transport.
• A private vet observed the clinical signs and called the EAD hotline to notify suspicion of the exotic animal disease FMD.
• A DPIRD vet attended the feedlot to examine and collect samples from the steers, noting rectal temperatures of 39°C–40°C and multiple ulcers on the buccal and the sublingual areas of affected cattle. No vesicles were detected, and no mucosal skin flaps were present. The steers were not lame, and no foot lesions were observed.
• Ensuring the use of correct personal protective equipment (PPE), the DPIRD vet collected complete blood samples, lesion swab samples in viral transport media and very small fresh gum biopsies from the edges of the lesions and submitted to the DPIRD laboratory for urgent testing.
• A second DPIRD vet attended the property of origin to examine cattle from the same cohort as the affected steers. Although there were no signs of salivation, on closer examination there were oral lesions on seven steers that were examined (Figure 1). Samples were submitted to the DPIRD laboratory for testing.
• There was no reported history that would identify a possible pathway for the introduction of any vesicular diseases.
• Samples were tested at DPIRD and were also sent to the Australian Centre for Disease Preparedness (ACDP, previously the Australian Animal Health Laboratory) for testing. 
• Testing for the reportable diseases FMD, vesicular stomatitis, bovine viral diarrhoea Type II and malignany catarrhal fever returned negative results.
• Testing was positive for the parapox virus, bovine papular stomatitis virus, by electron microscopy and by PCR.
• Bovine papular stomatitis is a mild, self-limiting viral disease usually affecting cattle less than two years old. Infection with this virus usually shows no clinical signs in affected cattle, but when signs do occur they will typically manifest on the skin and mucous membranes, particularly around the mouth. People in close contact with infected animals may develop skin lesions and pustules on their hands, arms or legs.
• Clinical signs consistent with FMD should always be reported to a DPIRD vet or the Emergency Animal Disease hotline on 1800 675 888. Early detection supports faster and cheaper eradication.

Secondary photosensitisation in Merino ewes in the Midwest

• In a flock of 550 mixed age Merino ewes, six had to be euthanised due to severe signs of jaundice, dehydration, facial swelling and scabbed oral lesions. More than 30 other ewes were mildly affected with swollen faces, jaundice and scabbing muzzle lesions (Figure 2).
• The producer contacted their local DPIRD vet to investigate the high morbidity and unusual signs of disease in their flock.
• The flock had moved onto a new pasture ten days earlier, which contained the weed caltrop (Figure 3). Caltrop is widespread throughout WA and can be identified by its star-shaped spiny burrs and small yellow flowers. Seeds remain dormant in the soil and germinate following summer rains.
• On post-mortem of one ewe, there was diffuse icterus of the carcase, bronchopneumonia and a swollen, yellow liver (Figure 4). Blood samples from three sheep, and faeces, fresh and fixed samples from one euthanised ewe were submitted with a provisional diagnosis of caltrop toxicosis and secondary photosensitisation.
• Histopathology revealed acute hepatocellular necrosis and acute renal tubular necrosis, both associated with formation of acicular clefts. This pattern is characteristic of steroidal saponin toxicosis, the hepatotoxic compound present in the weed caltrop.
• Testing of blood and liver samples excluded the exotic disease bluetongue virus. In the acute stage, sheep with bluetongue may present with pyrexia, salivation, nasal discharge causing crusting around the nostrils, swollen lips and tongue which may extend to include the ears, and petechial haemorrhages of the mucous membranes of mouth, nose and eyes.
• Although bluetongue virus is present in a monitored zone across northern Australia, bluetongue disease has never been reported in Australia. Suspicion of bluetongue virus disease must be reported immediately to your DPIRD vet or the EAD hotline on 1800 675 888.
• Other differential diagnoses in this case included the reportable diseases peste des petits ruminants, vesicular stomatitis and FMD. PCR and antibody testing was negative for all these diseases.
• The affected group was moved into a new paddock with no caltrop and plenty of shade. Livestock affected by photosensitisation should be protected from sunlight as it activates photosensitive substances in sparsely haired skin, which results in dermatitis and muzzle erosions. In the recovery period, access to high-protein feed should be limited.
• Results from this investigation help to provide evidence that WA is free from EADs and supports our access to markets.

In winter, watch out for these diseases

Disease, typical history and signs	Key samples
Arthritis in lambs Erysipelothrix rhusiopathiae is the most common cause of bacterial arthritis in lambs in WA. Lambs are most susceptible to infection soon after birth (via the umbilicus), at marking, mulesing and shearing. Any break or wetting/softening of the skin can allow entry of bacteria and development of arthritis. Differentials include endemics such as footrot, foot abscesses, laminitis from grain overload, scabby mouth extending to the lower legs, rickets, white muscle disease and exotic diseases such as FMD,  bluetongue virus disease. Prevention involves ensuring hygienic mulesing and shearing practices in lambs and/or a vaccination program in ewes prior to lambing if erysipelas arthritis has been identified as the cause. Read more on arthritis in sheep.	Ante-mortem: N/A Post-mortem: Swab of joint fluid/ synovium in transport media for culture Fixed joint capsule and muscle Fixed bone/joint sample if lesions or deformity
Copper deficiency in sheep and cattle Seasonal variation in the availability of copper from pastures makes sheep and cattle most at risk of a deficiency during late winter and spring. Young lambs, pregnant or lactating animals or cattle with heavy worm infestations are most at risk of copper deficiency. Clinical signs in cattle include ill-thrift, rough hair, sometimes loss of pigment around eyes, sudden death Clinical signs in sheep include ill-thrift, increased incidence of fractures, enzootic ataxia in unweaned lambs. Treatment and prevention revolve around copper supplementation which may include individual animal treatments, providing mineral licks or applying fertilisers. Read more on copper deficiency.	Ante-mortem: 10mL and 10 samples or 10% of the cohort in lithium heparin tubes. Post-mortem: 100g of fresh liver sample. In cases of adult sheep or cattle with ill-thrift and diarrhea consider Johne’s disease exclusion testing.
Bovine anaemia Theileria orientalis group (BATOG) BATOG occurs in southern WA where the bush tick, Haemaphysalis longicornis, is found. Infected ticks spread the blood parasite T. orientalis. Only infected ticks will transmit disease. Young cattle (2–3 months old), late-pregnant and recently calved cows in early lactation are most likely to be affected The disease may cause deaths in young stock. Healthy young stock that become infected may develop protective immunity but will continue to carry the parasite. Common signs: anaemia and pallor, fever, weakness, red urine, jaundice, death, late-stage abortions and premature births. Differential diagnoses: milk fever, leptospirosis, bracken fern or brassica poisoning, copper or zinc toxicity and reportable diseases babesiosis and anaplasmosis. There is no specific treatment, but supportive care is recommended. Read more on the BATOG webpage.	Ante-mortem pre-treatment: 10mL blood in EDTA tubes. 10mL blood in lithium heparin Blood smear Blood test at least 10 or 10% of the cohorts for herd testing Live ticks in a container with damp cotton wool or dead in 70% alcohol + 10% glycerol. Post-mortem: Bone marrow Aborted foetuses chilled or fixed tissues and fresh and fixed placenta Fixed and fresh liver and spleen.

Note: Always include base samples and any clinical or gross lesions in submissions. For sample submission advice, contact your local DPIRD vet or the duty pathologist on +61 (0)8 9368 3351.

Register soon for your DPIRD regional private vet workshop

Don’t miss your chance to attend the regional private vet workshop in coming soon in August.

Topics covered will include:

• Updates on Indonesian situation with lumpy skin disease and Foot and Mouth disease
• Signs of LSD and FMD and what to do if you see these signs
• Japanese encephalitis in Australia
• Helping your clients manage the Johne’s disease risk
• Information on the emergency disease watch hotline
• Discussion of interesting cases by you, your local Field Vet and a DDLS Pathologist
• Case handling tips for suspect exotic animal diseases - precautions to avoid the possibility of spreading a disease

 Participation is free to rural practitioners.

 Contact your local DPIRD field vet to register your interest and to find out more details!

Exotic disease in the spotlight: lumpy skin disease

• Lumpy skin disease (LSD) virus is a Capripoxvirus that affects cattle and buffalo.
• LSD first occurred in Africa. From the late1980s it was detected in parts of the Middle East, from 2012 in Europe, and from 2019 in mainland South-East Asia, gradually moving east. In March 2022, it was detected in Singapore and Indonesia. LSD has never been recorded in Australia, but its presence in near neighbours has increased the likelihood of introduction.
• Bos taurus cattle are more susceptible to the disease than Bos indicus breeds, with some dairy breeds (Jersey, Guernsey, Friesian and Ayrshire) particularly susceptible. Asian water buffalo (Bubalis bubalis) can be infected, but clinical disease may be milder.

 

 

Clinical signs 

• Typically presents as fever, multiple nodules on the skin and mucous membranes, which commonly become necrotic. Necrotic nodules may also occur within the alimentary system. 
• Severity of clinical signs may vary from inapparent to severe, and disease signs in Bos indicus cattle may be difficult to see. 
• Signs generally include a fever lasting 6-72 hrs, increased ocular, nasal and pharyngeal secretions, inappetence, milk drop, depression and reluctance to move. After 1–2 days nodules will erupt on the skin – these may cover the whole body or may be localised. The nodules will be raised, red and may be weeping. Regional lymph nodes will be enlarged, and regional dependent oedema may occur.  
• If the respiratory tract is involved, respiratory distress may occur. Pneumonia is a common complication and may be fatal. 
• The nodules may slough leaving full thickness lesions in the skin which commonly fill with purulent exudate. Scabs may also form on these nodules and may fall off, leaving large holes in the hide that can become infected.
• There is a rapid loss of condition, lesions may persist for 4-6 weeks and can take up to six months to fully resolve.

What to do if you see signs

Lumpy skin disease is a reportable disease in Australia. Eradication of LSD is difficult and early detection is essential for successful control and eradication. If you investigate a disease with these signs, contact your DPIRD vet or the emergency animal disease hotline on 1800 675 888. 

More information on LSD can be found on our webpage.

Sampling guide for investigating skin lesions

DPIRD encourages and assists vets to investigate cases where livestock show signs similar to reportable diseases. Correct sampling increases the likelihood of a definitive diagnosis. Where possible, a full base sample set of blood (EDTA and plain tubes), fresh tissue and fixed tissues should be submitted. DPIRD’s livestock disease veterinary sampling guide provides guidance on general sample collection.

Samples to investigate skin lesions

Sample	Storage	Comments
Skin/mucous membrance (fresh and fixed)	Fixed can be held at room temperature, fresh samples should be chilled.	Fresh tissue biopsy preferred. Ensure samples are representative of lesions. For large lesions, sample interface with normal tissue and areas of different colour or consistency. See DPIRD’s histopathology sampling guide.
Vesicle fluid in viral transport media	Chilled	N/A
Swabs in transport media	Chilled	Submit swabs of mass and / or exudate.
Scabs or crusts	in plain container	N/A
Samples of relevant feed or plants (ergot etc.)	Chill fresh samples	If submitting hay samples, a minimum sample weight of 100 grams is required. Collect samples from up to 10 bales, up to 1kg total weight.
Maggots	Place maggots in boiled water for 5-10 seconds until they appear white and float, then place into alcohol (70% or higher). See the Northern Australian Biosecurity Surveillance network guide for collecting maggots for more information.	Ensure clean sampling equipment is used and individual specimens stored separately to prevent DNA cross contamination. If possible, provide a photo in situ.
Photos of skin lesions	N/A	N/A
Blood	Plain and EDTA blood tubes	For PCR or ELISA if required.
Additional base sample set	Variable	See DPIRD’s livestock disease veterinary sampling guide for full list.

WA Livestock Disease Outlook highlights the benefits of surveillance

Australia’s ability to sell livestock and livestock products depends on evidence from our surveillance systems that we are free of particular livestock diseases. The WA livestock disease outlook – for vets summarises recent significant disease investigations by DPIRD vets and private vets that contribute to that surveillance evidence.

Feedback and subscriptions

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