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Local disease watch - July 2016

Liver fluke cause deaths

Heavy burdens of liver fluke killed both sheep and cattle this month. Adult liver fluke are blood-sucking parasites that live in the bile ducts of grazing animals including sheep, cattle and goats. Eggs are passed in faeces, and larvae infect small fresh-water snails that inhabit slow-flowing water in creeks, swamps and springs. Animals pick up new fluke when grazing these wet areas of the paddock.

Tests have shown a resurgence of liver fluke on many properties that have been fluke-free for the past decade or so. Fluke reduce growth rates and milk production, and large numbers can kill. In the cases investigated, the yearling cattle were heavily infested with liver fluke, and one died from the effects of the constant blood loss. Ironically, the sheep died following treatment for liver fluke. Masses of dead fluke clogged the livers of some sheep, causing liver failure.

Not all properties and not all paddocks will have habitat suitable for liver fluke snails. Blood tests and dung tests can help diagnose liver fluke in winter. Be mindful that about one third of livestock properties in eastern NSW have liver fluke. So if you purchase stock, they may have fluke even if there is nowhere on your farm for fluke snails to live. Treatment options include oral, injectable and backline products. Check the label before you buy; most fluke treatments have lengthy export withholding periods, and some are not suited to milk production.

Pregnancy toxaemia in sheep

High rates of twins and weight loss in late pregnancy are contributing to pregnancy toxaemia in some flocks. The first indication of trouble may be a ewe standing alone, gazing into space. She is unaware of your presence, and her breath may have a strong smell of ketones (smells like nail polish remover). They collapse soon after, and are difficult to treat. Use this first case as a trigger to increase the feed available to the mob. The space available for food is reduced by “a belly full of legs and heads”, so concentrate supplements such as grain or pellets are preferred to hay. But remember to introduce cereal grain or pellets gradually to avoid poisoning.

Three-day sickness

More cases of three-day sickness (bovine ephemeral fever) were detected in cattle on the South Coast in the Nowra area, as far south as Conjola. Owners observe sudden onset of lethargy, lameness and fever in affected cattle. They often then lie down for a day or two requiring nursing before recovery. Fat or heavy animals, particularly bulls, may need veterinary treatment.

Pink-eye in sheep

Several cases of pink-eye have been reported in sheep this month. We usually associate pink-eye with long grass, dust and flies, as all these help to spread the infection from one sheep to the next. Owners have been surprised to see severe pink-eye cases mid-winter. Symptoms include blindness and excess tear production, followed by a cloudy eye. Often the sheep are being hand-fed, or are jostling around a self-feeder or lick block, with infection spread by close contact. Sheep pink-eye may be caused by about six different organisms, including the agent responsible for cattle pink-eye. Antibiotic eye ointment works well in cattle, but some sheep strains of pink-eye respond best to a long-acting antibiotic injection available from your vet.

Changes to Johne’s Disease management

A national review of Johne’s disease will see changes made to the management of the disease from 1 July 2016. Details are still being finalised, but the new arrangements aim to reduce government regulation in favour of management of Johne’s disease by industry. Johne’s disease will still be notifiable, but regulations requiring compulsory Dairy Assurance Score declarations for dairy cattle sales, and quarantines for infected beef herds will be abolished, as will tracing cattle movements from infected herds.

Producers are being encouraged to ask for health statements when trading livestock, to help identify the potential Johne’s disease risk of a herd or flock. Modified voluntary Dairy Assurance Score and Beef Assurance Score schemes are proposed.

Some interstate movement requirements will change in response to the new national guidelines. At the same time, Johne’s disease will be regarded as a single disease, rather than distinct strains that affect either sheep or cattle. This will free up interstate trade for some, while making it more difficult for others.

More details are expected within days, and will receive widespread publicity. Contact your District Veterinarian to discuss how these changes may impact your business.