Managing animals in wet conditions
Ongoing wet conditions can lead to a range of animal health concerns for livestock producers.
The following animal health issues are considered by veterinarians to warrant advice to producers to be extra vigilant and to be monitoring stock carefully.
The diseases in this article are not a complete list of common diseases, just some diseases that can be seen more frequently in ongoing wet and cool conditions. Where deaths, morbidity, acute or chronic ill-health or ill-thrift is occurring in a herd or flock there may be other causes and producers are encouraged to seek advice from their veterinarian.
Barber’s Pole (Haemonchus contortus) is a blood sucking internal roundworm that can be fatal to sheep and goats.
Relatively mild and wet conditions over summer meant that:
- Significant numbers of worm eggs are hatching and becoming infective larvae (L3)
- That infective (L3) stage larvae could potentially survive on paddocks for several months.
Anaemia, lethargy, bottle jaw, decreased feed intake and weight loss are some of the typical signs in infected sheep and goats. Diarrhoea is not a sign of Barber's Pole. Production losses can be occurring before signs of illness are visible. Most vulnerable stock are weaners and lambing ewes.
Producers should have an active monitoring and control program in place which includes regular worm egg counts, larval culture, drenching program and grazing management designed to reduce exposure of vulnerable stock to infected pastures.
Foot abscesses and foot scald
Another serious disease in sheep is foot abscess. This causes severe lameness, impacting negatively on animal welfare and productivity. An abscess in the heel is a bacterial infection caused by organisms usually found in the gut and faeces. Sheep are vulnerable to heel abscess when grazing wet paddocks for extended periods of time.
The foot of the animal does not need to be injured for infection to occur, an abscess can result from the skin simply being wet for a long period. The bacteria gradually invade the soft, wet skin tissue and begin to form an abscess under the skin which can be intensely painful for the animal. Sheep with heel abscesses don’t like to move around. Weight loss results, which is particularly risky for pregnant and lactating ewes and their lambs. Rams may not mate effectively during joining and may have reduced fertility as a result of a heel abscess. Toe abscesses are caused by actual damage to the toe region of the hoof. These are more common in the front hooves of sheep.
Scald or interdigital dermatitis is another condition common in sheep exposed to lush wet green paddocks for extended periods of time. This is a mild infection of the skin between the hooves of sheep. Scald can create the conditions for more severe causes of lameness such as foot abscesses or footrot.
Accurate diagnosis of lameness problems in sheep is important. Footrot, another cause of lameness, is a notifiable disease under state legislation. Consult your veterinarian early to ensure the correct diagnosis.
In cattle, scald can be known as footrot, but the correct term is interdigital necrobacillosis. Again this is caused by prolonged exposure to wet muddy conditions causing interdigital skin to become soft, allowing the entry of the bacteria. This is a painful condition which can lead to severe and chronic lameness.
Yersiniosis, a bacterial disease caused by Yersinia bacteria is a disease of sheep and cattle that is known to be a problem during prolonged wet conditions going from autumn into winter. Outbreaks have been reported after heavy rainfall and flooding so this disease can be known as ‘flood mud scours’. Infected stock show signs of lethargy, inappetence, raised body temperature, dehydration, and diarrhoea. When detected and correctly diagnosed early, infected animals should respond to antibiotics. Good nutrition, particularly during winter, has an important role in preventing this disease.
Coccidiosis in sheep, goats and cattle is caused by a microscopic parasitic protozoa (Eimeria ssp). Infected calves can have severe, blood-stained diarrhoea which is why the disease is also known as black scours. Straining to defecate, soiling of the hind legs, lethargy, weakness, dehydration and anaemia are typical signs. Calves that are under stress are most susceptible.
Sources of stress can be management related (weaning, transportation, over-crowding), nutritional, or weather related. Avoiding faecal contamination of feed and water sources by having raised and well drained trough areas is important to reduce exposure of vulnerable animals and reducing stocking rates can assist in prevention and control. Coccidiosis is not the only cause of diarrhoea in calves, so early and accurate diagnosis is important.
As with cattle, coccidiosis in sheep mainly affects young animals under stress. Goats do not develop the same immunity that sheep do, so the disease may be seen in goats of any age. Affected animals may scour, lose weight, appear depressed and be hunched over. Deaths can occur in severe cases.
Liver fluke (Fasciola hepatica) is a parasite that affects any species of livestock with a liver. It is a zoonotic disease which means people can be affected too. The lifecycle of the parasite needs watery, marshy areas.
With the current wet conditions there will be no shortage of suitable habitats for the intermediate host; aquatic snails (Lynmaea tomentosa), in which the larvae develop, then transmit the larvae to pastures where animals are grazing, where after being ingested, the larvae then mature inside the liver where the damage occurs.
Liver fluke often goes undetected in herds and flocks causing production losses. However, the disease can develop from chronic, to sub-acute, then to acute fasciolosis.
Signs in affected animals relate to loss of condition, bottle jaw caused by blood loss and low protein and occasionally scouring. Liver fluke can predispose stock to black disease, a clostridial disease. Black disease is preventable by vaccination with a 5-in-1 vaccine.
Flystrike is a major disease and welfare issue for Australian sheep. It occurs in warm weather when the fleece of sheep is wet, such as from spring or summer rains where there are dags present on sheep. It occurs less frequently in early autumn.
Heavy rainfall and floods during warm spring and summer months can increase the risk of flystrike. All breeds of sheep can be affected, mainly from body strike where fleece rot has occurred.
Other animals can be struck by blow flies where they have oozing sores – such as when they have been lying down for long periods – or in wounds.
Regular inspections of all sheep mobs and goat flocks are vital for signs of flystrike. Sheep must be inspected at least every 2 days if preventative chemical has not been applied.
Flooding rains may reduce the protective period of the chemical. Begin inspecting any mobs where treatment was applied some weeks ago.
For high-risk mobs, follow these steps:
- Crutch, dag and pizzle ring susceptible sheep or mobs.
- Emergency shear to prevent or control body strike.
- Immediately treat any sheep seen with flystrike.
- Dispose of struck wool to reduce fly numbers (see solarisation).
- Control scouring by good nutritional and pasture management and appropriate worm control.
- Feed good quality hay when pastures are lush to bind faecal material.
- Ensure clean drinking water to reduce risk of scouring.
- Move susceptible stock to low-risk paddocks if possible – such as higher ground that is likely to remain drier.
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Pink eye, or infectious keratoconjunctivitis, is a highly contagious, painful and debilitating disease that can severely affect animal productivity.
In wetter years its incidence may increase due to the proliferation of flies and long grass, which facilitates its spread.
Pink eye usually occurs in young cattle in their first summer. After this initial infection, cattle develop immunity to the disease but may remain carriers of the bacteria, Moraxella bovis, which can lead to future outbreaks in following years.
The clinical signs of pink eye include clear and watery tears, signs of irritation, an aversion to sunlight, reddening and swelling of the eyelids and cloudiness of the eye.
In a small percentage of cases, an affected eye may form an abscess and rupture, leading to permanent blindness.
While most affected eyes completely recover after three to five weeks, a number may be left with scarring on the surface.
Pink eye can be treated with sprays, ointments, injections and patches or a combination of these treatments. Extra care should be taken when mustering cattle for the purposes of treatment for pink eye, as factors such as dust and flies may enhance the spread of the disease.
Caution should also be taken not to confuse pink eye with other conditions of the eye, such as a grass seed in the eye, eye cancer and other eye infections.
An outbreak of pinkeye may be prevented through vaccination three to six weeks before the onset of the pink eye season.
Other control measures include controlling fly numbers to limit the spread of bacteria from animal to animal; prompt segregation and treatment of pink eye in affected stock; and avoiding unnecessary yarding of cattle during periods where the risk of outbreak is high.
Integrated herd or flock health management
To lower the potential financial and productivity losses to your farm business due to animal health issues, an integrated herd or flock health approach is best practice.
An integrated health management system incorporates a range of preventative as well as reactive approached to managing herd and flock health and welfare. These include:
- Having an up-to-date biosecurity for your farm. Visit farmbiosecurity for more information
- Documenting the common diseases in your area, understanding how and when they occur and what impact they may have on your business
- Having a disease prevention and management plan which is developed with your veterinarian
- Regular and timely vaccination, drenching and ensuring that drench resistance is considered in the drenching program
- Faecal worm egg counts when recommended
- Regular visual monitoring
- Managing the nutritional and environment stress factors in stock which contribute to disease
- Use grazing management to reduce the risk of diseases from internal parasites.
- Have these two phone numbers stored in your phone
- Your regular veterinarian
- Emergency Animal Disease Watch Hotline: 1800 675 888
- Download the Notify Now app to your phone.
The diseases in this article have been highlighted as diseases of greater concern for farmers due to the current ongoing wet conditions in Victoria.
Livestock owners should always be vigilant for any signs of ill-health or ill-thrift in their stock, and implement the appropriate response in a timely manner, which in some cases should (or must) include consulting your veterinarian and in more serious cases calling the Emergency Animal Disease Watch Hotline on 1800 675 888.
Unexplained or unexpected deaths in livestock should be investigated. Veterinarians should always be consulted early, as this gives you as the owner, and the veterinarian more options to respond to animal health issues in the herd or flock, with potentially better outcomes including limiting the impact of a disease in the herd/flock.