Producers impacted by flooding are encouraged to check their livestock for unusual symptoms of illness.
A number of plants and diseases that thrive during and after rain can have serious impacts on livestock.
Three-day sickness, also known as bovine ephemeral fever, is spread by biting insects. It can cause temporary or permanent infertility in bulls, loss of body condition, decreased calf-growth rates and milk production, and abortion. In a small percentage of affected animals, it can be fatal.
Initial symptoms include signs of a fever, muscular stiffness, lameness, shivering, drooling saliva and discharge from the eyes and nostrils. Treatment with anti-inflammatory drugs has been shown to reduce the course of the disease. Consult your veterinarian for an appropriate anti-inflammatory drug, considering the withholding period of the drug for meat and milk.
Spread by midges, Akabane affects the nervous system of a foetus in pregnant females. It causes deformities such as limb malformations and brain lesions in calves. Diagnosis cannot be made until a calf is born. There is no successful treatment or means of control. In an area known to be endemic, breeding stock should be introduced to the area at an early age to gain immunity prior to joining.
Blackleg most commonly affects fast-growing cattle younger than two years of age. It is caused by bacterial spores from contaminated environments entering the animal through small wounds or being ingested. This disease may not occur immediately, and it may be some time before symptoms show.
Erosion and movement from floods provide favourable survival conditions for blackleg spores. Common signs include fever, severe depression, gassy swelling under the skin or in muscles even before death, or sudden death - usually with rapid bloating of the carcase. Vaccinations are highly effective as prevention if a full course is given.
Leptospirosis is most commonly found in warm, wet climates and affects all farm animals, including dogs and horses. It is generally spread by the urine of infected animals, through ingestion or contamination of cuts and abrasions.
The disease can be fatal and common symptoms include fever, abortion, infertility and weak newborns. In young animals, disease can result in severe depression, high temperature and blood in the urine. In cattle, a specific form of mastitis known as milk-drop syndrome can occur. Horses can develop blindness due to inflammation of eye tissues.
Even if already infected, vaccination can prevent clinical leptospiral disease from developing, though the animal will remain infected and able to transmit disease organisms in reduced numbers.
Botulism is a progressive paralysis and is generally fatal to livestock. Botulism is caused by the ingestion of a toxin found in rotting animal and plant material including carcases. Following floods, decaying vegetation and carcase materials can be a source of botulism toxin.
Animals may consume decaying material inadvertently, deliberately if hungry or when protein or phosphorus deficient. Maintaining an up-to-date vaccination program is the best approach. Phosphorus supplementation may also assist.
Toxic plant seeds can become displaced during flooding and spread easily, prompting new growth in areas previously not infested.
There are 33 species of crotalaria known in Queensland - most of which are toxic to livestock. Crotalaria predominantly cause pyrrolizidine alkaloid poisoning but are also responsible for chillagoe horse poisoning or oesophageal ulceration of horses (see C. aridicola or C. medicaginea) and Kimberley horse disease (also known as walkabout disease). While some species are not toxic, all crotalaria should be treated as potentially lethal.
Common signs of crotalaria poisoning in cattle include poor growth or wasting, jaundice, weakness and collapse, aimless walking, staggering and apparent blindness. Skin irritation and reddening (often progressing to some skin death), drooling and diarrhoea occur occasionally. Horses affected by crotalaria poisoning show similar symptoms to cattle but can also experience paralysis of the tongue and larynx and breathing difficulties. Two species of crotalaria are known to cause ulcers in the oesophagus of horses, resulting in an inability to swallow food and water.
In most cases damage is permanent but some animals can recover with supportive therapy - including good feed and nutritional supplements - if discovered early.
Grasses and sorghum
Common plants can also become toxic during overcast conditions or if plants are stressed or wilted. Under these conditions, urochloa grass, button grasses, sorghum species and the common native couch grasses can accumulate nitrites or prussic acid that are toxic to livestock. These grasses and sorghum species can be fatal to livestock, but prompt treatment can save affected animals.
Signs of nitrite poisoning from ingesting urochloa and button grasses include rapid, gasping breathing, bluish/dark gums, convulsions and muddy brown-looking mouth and eyes. Affected livestock may also walk through fences or into objects.
Signs of poisoning from prussic acid, which can build up in native couch grass and sorghums, include rapid deep breathing, salivation, a rapid weak pulse, muscle twitching or trembling, spasms, staggering and sometimes a bluish discolouration of the gums.
If you notice any of the above symptoms in your livestock seek advice urgently. Some plant toxins can be fatal within an hour. Therefore, in many cases urgent action is the key to saving animals.
This article was produced by FutureBeef-a collaboration between Meat & Livestock Australia and the Queensland, Northern Territory and Western Australian agriculture departments.
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