WA Livestock Disease Outlook - for vets

Recent livestock disease cases in WA

Hendra virus exclusion in a horse showing neurological signs in the Pilbara

• An eight-year-old horse initially showed unusual behaviour (running away) and later, head pressing, ataxia, lethargy, recumbency. On examination the animal was tachycardic.
• No other horses on the property were affected.
• Key samples: Blood testing on EDTA, clotted and lithium heparin samples indicated hepatobiliary damage. Creatinine kinase was elevated, which could be attributed to the ataxia and recumbency.
• Reportable rule-out: Given the clinical signs, Hendra virus and equine encephalomyelitis (Eastern, Western and Venezuelan), equine herpesvirus and Murray Valley encephalitis and Ross River virus were tested for at DPIRD Diagnostic Laboratories (DDLS) and Australian Animal Health Laboratory (AAHL). Testing concluded none of these diseases were present.
• The hepatopathy and grazing history in this horse were consistent with pyrrolizidine alkaloid (PA) toxicity (Kimberley walkabout disease).
• Grazing Crotalaria spp. is a well-known cause of PA toxicity in livestock. This plant is known to occur in the Pilbara (see map of recorded sites of Crotalaria in WA on the Florabase webpage).

African and classical swine fever ruled out in pig at abattoir

• African swine fever (ASF) and classical swine fever (CSF) are highly contagious, unrelated viral diseases which affect pigs. They both can cause high mortalities and are exotic to Australia.
• In the severe form, signs include fever, loss of appetite, skin reddening, blue extremities, coughing, laboured breathing, diarrhoea, abortions and sudden death. The presentation may be milder and changes to the kidneys and tonsils may be observed at an abattoir.
• A grower pig presented for slaughter was found to have bilateral renal petechiation and samples were submitted to DDLS for investigation.
• In this case, ASF and CSF tests were negative. Porcine circovirus associated disease (porcine dermatitis and nephropathy syndrome) was identified as the cause of the renal pathology, which can also produce purple skin lesions and vascular organ lesions, particularly affecting the kidneys. Recent findings suggest a novel circovirus, PCV3, is associated with PDNS (https://www.ncbi.nlm.nih.gov/m/pubmed/27795441/).
• ASF and CSF could enter WA pig populations by feeding illegally imported pig meat or meat products to pigs (swill feeding). Contact with infected pigs or fomites could rapidly spread the disease causing high losses.
• For signs consistent with ASF or CSF, contact the Emergency Animal Disease hotline on 1800 675 888.
• Read more on Classical swine fever and African swine fever.

In summer, watch for these livestock diseases:

Disease	Typical history and signs	Key samples
Bovine anaemia due to Theileria orientalis group (BATOG)	BATOG occurs in the southern areas of WA where the bush tick, Haemaphysalis longicornis, is found. Infected ticks spread the blood parasite Theileria orientalis. Only infected ticks will transmit disease. Signs include anaemia, abortion, jaundice, laboured breathing, weakness, collapse. Severity is increased during stress. The disease may cause deaths in young stock. Healthy young stock that become infected may develop protective immunity and signs may never develop but they will continue to carry the parasite. 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 for BATOG, but supportive care is recommended. Read more on the BATOG webpage. Eligible disease investigations can be subsidised by the SDI program – contact your DPIRD field vet officer.	Antemortem: 10mL blood in lithium heparin 10mL blood in EDTA Blood smear Postmortem: Fixed and fresh liver and spleen
Kikuyu poisoning	Kikuyu normally grows spring-autumn and can provide valuable summer feed, however poisoning can occur under certain conditions. A long dry spell followed by heavy summer rain can cause rapid grass growth and lush paddocks ungrazed prior to rain pose the biggest risk. Signs may include unusual vocalisation, bloating, hypersalivating, ataxia, recumbency and sham drinking. Moving animals immediately off the affected paddock and providing supportive treatment may alleviate signs. A confirmed case of poisoning in cattle in the Great Southern occurred in January with several reports of cattle losses with similar signs. Always report animals with drooling or mouth ulcers to a DPIRD vet as it could be a vesicular disease such as foot-and-mouth disease. Sudden death cases may also be eligible for subsidised investigations. Read more on the kikuyu webpage.	Antemortem: 10mL blood in lithium heparin, EDTA and clotted Faecal samples Postmortem: Base sample set including rumen content and brain Fixed reticulum and omasum Pasture samples: contact DDLS for advice
Water quality issues	Water quality can be reduced where the salinity is excessive due to evaporation over summer. Water points can become toxic with blue-green algae when the water temperature increases in summer. Water contaminated with organic matter can result in botulism in cattle or salmonellosis in sheep. Stock may refuse to drink water or drink a reduced amount when the water is poor, which reduces feed intake and growth rate. Regularly check water points to ensure pipes and nozzles have not become blocked and that the water quality has not deteriorated. Read more about water quality for livestock including guidelines for water salinity by species and water testing.	Water samples can be tested for salinity and blue-green algae at DDLS 500mL of water in clear glass or plastic bottle which has been rinsed thoroughly in the water to be sampled.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reminder to be aware of melioidosis potential after heavy rain

With the recent rainfall across the state, DPIRD encourages vets to monitor for potential cases of melioidosis in animals. Melioidosis is mainly associated with tropical and subtropical regions, but it has occasionally been detected in temperate regions. Recent heavy rainfall may increase the risk of melioidosis, and cases have occurred previously in the Chittering and Toodyay shires. If you see signs of disease in animals that could be melioidosis, contact your DPIRD Field Veterinary Officer for assistance. While the risk of transmission of melioidosis from animals to humans is low, personal protective equipment should be worn to prevent droplet or respiratory infection when dealing with suspect cases.

For more information about melioidosis, including species-specific clinical signs, see the melioidosis webpage.