Local Disease Watch - February 2016
District veterinarians working for South East Local Land Services visit farms to investigate herd and flock problems in livestock. The information we gain from these investigations improves livestock production and animal welfare, and helps to ensure that Australia is free from certain animal diseases.
Several worm outbreaks in sheep and goats have caught producers off-guard. A long spell of hot, dry weather was expected to reduce numbers of worm larvae on pasture. However, rainfall on some properties has allowed worms to rapidly build-up. Barber’s pole worm cases, with tell-tale anaemia and weakness, have been seen across the district. Even on farms which missed most of the rain, barber’s pole worms have flourished in the milder environment of valley floors.
Brown stomach worms and in some cases black scour and thin-necked intestinal worms have also produced high worm egg counts. While these worms typically cause scouring, the lack of green feed in many paddocks means sheep lose body condition due to worms, without scouring. Laboratory tests on faeces are a relatively cheap and quick way to monitor worm activity.
Warts on cattle
We commonly receive enquiries at this time of year about warts on cattle. Warts are very common on young cattle, and outbreaks are commonly seen within a few weeks of weaner sales. Multiple hairless, raised lumps from a few millimetres to several centimetres diameter with a rough, dry surface are usually found on the head and neck.
Warts are caused by a virus, the bovine papillomavirus, which differs from the wart virus of other animals. There are several strains of cattle wart virus, some causing lesions on the teats of adult cows, and the penis of bulls.
This very hardy virus survives environmental extremes and disinfectants. The virus is spread by direct contact between animals, gaining entry through broken skin. Lice, biting flies, ear tags and injection needles may also transmit infection.
Most cases of warts are mild, and usually self-cure. Unfortunately, there is no guide to how long warts will last. Most cases resolve within a couple of months, but some warts remain for twelve months. Some warts, particularly those on the end of the penis, may be candidates for surgery. In other cases involving large numbers of warts in valuable cattle, use of a specially made vaccine or immune stimulant may be considered.
Lameness investigations in sheep
Benign footrot, or scald, is very common in sheep and goat flocks. Scald is a bacterial infection which is estimated to occur in more than eighty percent of sheep flocks in our region. Scald commonly affects a very high proportion of sheep in the flock in winter and spring, when green pastures are dense and wet. As feed dries off, most feet also recover. Lack of extensive under-running of the sole of the foot distinguishes scald from virulent footrot. Flocks with a high proportion of sheep affected with scald frequently report more cases of foot abscess.
As part of a program to investigate the extent of virulent footrot, a large number of flocks have been inspected in our region. Some producers are surprised by the number of sheep we have found in their flock still affected by scald, in mid-summer. This has varied from just one or two percent to as many as thirty percent. Few of these sheep are limping, although some lameness is seen when sheep first start to move off the camp. Some sheep have three or four feet with raw, smelly ulceration between the claws, and occasionally maggots. These more severely affected sheep are often in low body condition.
Attempts to eradicate scald often fail, and this infection usually remains following successful programs that eradicate virulent footrot. Cattle are known carriers of scald, and the organism which causes it has even been found on healthy skin above the hoof.
Contact your District Vet for help with the diagnosis and treatment of foot conditions in your stock.
District Veterinarian, Goulburn