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Infectious diseases
Read our guide on vector-transmitted diseases for other diseases that can increase after flooding.
The immediate issues for livestock during and following floods often relate to trauma and exposure injury. However, other significant impacts on livestock can arise from infectious disease.
Clostridial (mainly blackleg) and leptospiral (lepto) infections represent a risk after flooding.
Botulism is a progressive paralysis from the ingestion of a toxin found in rotting animal material or on the bones of dead animals.
Prolonged wetness of wool can also lead to skin infections, the most common of which is lumpy wool in sheep.
This guide discusses some of the major infectious diseases that can arise after a flood, and what you can do to minimise the risks to your livestock and business.
Blackleg and leptospirosis
Clostridial (mainly blackleg) and leptospiral (lepto) infections represent a risk after flooding. This is because moisture provides more favourable survival conditions and the blackleg spores are exposed by the effects of soil erosion or movement.
Symptoms
When blackleg spores or leptospiral organisms enter an animal, disease may or may not occur immediately. For blackleg, some other precipitating event, such as an injury, is usually required for disease to develop. Therefore, it may be some time before the disease is actually seen.
Blackleg generally presents as severe disease with sudden/rapid death in animals less than 2 years of age, with rapid bloating of the carcass. There may be gas under the skin or in the muscles even before death.
For leptospirosis, disease in young animals may occur soon after infection, especially if the lepto involved is like L. pomona, resulting in severe depression, high temperature and often blood in the urine. Lepto infections in older animals may be asymptomatic or result in abortions. Abortions due to lepto do not usually occur until the third trimester of pregnancy, so significant abortion numbers might not be seen until months later.
Prevention
Vaccinations for both diseases are highly effective in preventing disease if a full course is given. Even if already infected, vaccination may prevent clinical leptospiral disease developing. The animal will remain infected and able to transmit disease organisms, though in reduced numbers. Several 7-in-1 formulations are available that enable you to vaccinate against both common leptospiral and clostridial diseases with one product. (There are many different leptospiral organisms but only 2 cause most lepto diseases in cattle.)
Also consider...
- Learn more about leptospirosis.
- Read our guide on vector-transmitted diseases for other diseases that can increase after flooding.
- Read the fact sheet about livestock diseases following floods (PDF, 198KB).
Botulism
Botulism is a progressive paralysis from the ingestion of a toxin found in rotting animal material or on the bones of dead animals. It is usually fatal, as it paralyses respiratory muscles. It is commonly associated with livestock chewing bones in an attempt to obtain phosphorus (P) when the pasture is deficient in it.
Pasture in many parts of Queensland is deficient in phosphorus due to a deficiency in the soil. However, in very good years, a relative deficiency of phosphorus may also occur in otherwise adequate situations. With rapidly growing pasture, energy and protein levels can be very high, and animals require high levels of phosphorus in their diet in order to utilise these nutrients. If phosphorus is not available in the pasture, animals may look to supplement the diet with bones. In these situations, botulism can occur.
Risks after flooding
After floods, decaying vegetation can be a source of botulism toxin. An immediate risk of botulism exists if animals consume carcass materials or decaying vegetation either inadvertently or in trying to meet a phosphorus need on marginal country. However, the risk may not arise until later in the year when the country dries a little, and the pastures recover and begin to 'explode' due to the moisture and nutrients deposited by the flood.
Prevention
Maintaining an up-to-date vaccination program is the best approach to preventing botulism; however, phosphorus supplementation may also help animals make better use of vigorously growing pasture.
Phosphorus supplementation may supply the extra phosphorus if given early. However, if cattle develop a habit of chewing bones, this habit may continue after their phosphorus requirement is met or the requirement has passed, with the risk of botulism remaining.
Also consider...
- Learn more about botulism.
- Read our guide on vector-transmitted diseases for other diseases that can increase after flooding.
- Read the fact sheet about livestock diseases following floods (PDF, 198KB).
Lumpy wool
Prolonged wetness of wool can also lead to skin infections, the most common of which is lumpy wool in sheep. While mild infections may not cause serious discomfort to sheep, lumpy wool can predispose affected sheep to flystrike and cause difficulty at shearing.
Symptoms
With lumpy wool, the fleece of affected sheep contains hard lumps, scabs or crusts. In extreme cases, the whole skin surface may be covered by scabs. Sheep may develop a ragged or lumpy appearance. There may also be lots of small scabs on the skin along the edge or upper surface of the ears, and also often on the lips, face, shanks and scrotum.
Treatment
In most sheep, the skin infection will cure itself in time and the hard lumps or crusts will lift away from the skin as the wool grows. For treatment of individual sheep, contact your veterinary surgeon. Adopt management procedures to prevent the spread of lumpy wool.
Also consider...
© The State of Queensland 1995–2024
- Last reviewed: 08 Sep 2021
- Last updated: 08 Sep 2021