Disease

Bovine diseases

Common bovine diseases to be aware of including 3 day sickness, clostridial diseases, Botulism, Pestivirus and Leptospirosis. Consult with your vet on the best vaccination protocol for your herd.

Bovine ephemeral fever (BEF)/ 3 day sickness

Bovine ephemeral fever (BEF) is a disease that affects cattle and occasionally buffaloes and is marked by a short fever, shivering, lameness and muscular stiffness. Also commonly known as 3 day sickness, BEF is an arthropod-borne virus (most likely mosquitoes) and widespread in Queensland.

The disease may cause serious economic losses through deaths, decline in condition, decreased milk production, lowered fertility in bulls, occasional abortions and delays in marketing.

BEF occurs most years in northern Australia and usually spreads from north to south, governed by season, rainfall and the relative distribution of insects. In most years, BEF cases start at the beginning of the wet season in northern Australia, and then spread south and east down the east coast. It then spreads into southern Queensland, and central and coastal New South Wales. It is less common in drought years but can occur following an extended period of drought.

Clinical signs

There are typically 3 recognised stages of bovine ephemeral virus.

The acute febrile stage appears suddenly and is especially noticeable in dairy cattle.

Affected cattle are likely to:

• show signs associated with a fever

• have a rectal temperature over 40°C

• shiver (in approximately 50% of cases)

• stand with their backs arched and heads held low, muzzles extended, drooling saliva

• have discharge from eyes and nostrils

• stop feeding and cud chewing

• have reduced milk production, especially in dairy cows.

The second stage is muscular stiffness and lameness in 1 or more limbs. Some secondary bloat may occur due to general inflammation of the abdominal cavity and ruminal stasis. Lameness may shift between limbs and joints may be visibly swollen.

During recovery, most affected animals resume eating and drinking. Animals may go down, with heavy animals in good condition being most affected. Some animals remain down due to muscle damage or damage to the spinal cord from constant struggling.

Vaccination available: Yes

Clostridial diseases   

Clostridial diseases are caused by anaerobic bacteria that are widespread in the environment, particularly in soil, and are often fatal.

The bacteria produce spores that can survive in the environment for a very long time.

Clostridial diseases include:

• tetanus

• blackleg

• black disease

• malignant oedema

• pulpy kidney

• botulism (see below)

Conditions when clostridial disease are likely to occur:

• in non-vaccinated animals

• tetanus – penetrating wounds (including marking wounds), foot trimming wounds, dog bites, grass seed punctures and dehorning

• blackleg – muscle bruising, especially in growing animals

• black disease – liver fluke infection

• malignant oedema – wounds, especially in females associated with recent birthing

• pulpy kidney – lush pastures, heavy grain feeding and a sudden change in feeding

• botulism (see below)

Clinical signs

• tetanus - stiff-legged gait followed by convulsions that are initially stimulated by sound or touch and that gradually increase in severity

• blackleg - severe lameness and swelling on the affected leg. Animals with blackleg are very depressed, with a fever and dry cracked skin. Sudden death is common

• black disease - animals with black disease are profoundly depressed and can have abdominal pain. Sudden death is common

• malignant oedema - a contaminated wound, often in females that have recently given birth, with local swelling. Animals with malignant oedema are depressed with a fever. Death is common

• pulpy kidney - animals with pulpy kidney have convulsions and sudden death

• botulism (see below)

Vaccination available: Yes

Botulism

Botulism is a disease caused by the botulinum toxin, which is produced by the bacterium Clostridium botulinum. Clostridium botulinum spores are common in the soil, and also in the gut of healthy normal cattle and other animals in tropical environments (which includes most of Queensland), where they are not a problem. Spores are the dormant form of the organism. Only the actively growing or 'vegetative' Clostridium botulinum bacteria produce botulinum toxin and it is the toxin that produces the disease. Clostridium botulinum spores will only germinate and grow under conditions where oxygen is totally excluded.

Botulism is commonly seen in the phosphorus deficient areas of northern Australia, where it is often associated with cattle eating bones and carrion to satisfy a craving for phosphorus and/or protein.

Reports of botulism have become more frequent in parts of Queensland that are not phosphorus deficient. Most of these outbreaks have been in intensively fed beef and dairy cattle. An increase in intensive feeding practices has occurred in the dairy and beef industries in Queensland, so the increasing risk of botulism outbreak has simply mirrored the increase in these feeding practices.

Botulism outbreaks can occur in intensively fed beef and dairy cattle when:

• the feed is contaminated with botulinum toxin that has been produced by the botulism bacteria growing in rotting animal or vegetable material in the stored feed. Contamination is in the form of the actual toxin.

• actively growing botulism bacteria, eaten in feed contaminated with rotting animal or vegetable matter, continue growth in the rumen and gut of cattle, producing toxin. This source of disease is called Toxicoinfectious botulism. Sufficient toxin is produced for the animal to develop botulism. In this way, a relatively small source of the botulism organism, like a dead snake in contaminated feed, can infect large numbers of cattle fed a mixed ration

• chicken litter, used as fertiliser on pastures and not incorporated into the soil properly, has been accessed by cattle and consumed.

Once produced, the toxin is quite stable and may remain in contaminated feed or water for some time. The time it takes to break down will depend on environmental conditions.

Clinical signs

Clinical symptoms of botulism vary dramatically depending on the dose of toxin to which cattle are exposed and any pre-existing immunity that may be present. Signs will vary from sudden deaths (animals collapse and die in a couple of hours) to a slowly progressive paralysis where animals may take days to die.

In the latter case, the first signs are cattle off their feed and water. They then develop a wobbly gait (staggers) and eventually go down. During the staggers stage, some cattle become aggressive. Not all cattle that develop botulism symptoms will die. Some mildly affected cattle will recover. Generally speaking, once cattle go down, their likelihood of recovery is poor.

Cattle affected by botulism do not develop a fever. They show no response to treatment for other common causes of 'downer cow syndrome' such as three-day sickness or milk fever. Cattle may progress to the stage where they have difficulty breathing and typically lie on their brisket with their hind legs stretched out behind them. Tongue paralysis may or may not be a feature of the disease (cattle cannot pull their tongue back in when it is pulled out of their mouth). 

Vaccination available: Yes

If you suspect botulism, contact your vet immediately for help with diagnosis and treatment. The disease can result in rapid, significant losses.

Pestivirus / Bovine viral diarrhoea virus (BVDV)

Pestivirus causes abortion, ill-thrift in young animals, diarrhoea and respiratory disease. Transmission is via direct contact with a carrier animal. The virus is common in cattle and many herds are infected.

Conditions when pestivirus is likely to occur

• close contact between cattle

• recent introduction of carrier animal(s) into a herd

• introduction of new cattle into a closed breeding herd

• introduction of new cattle into a breeding herd in the early stages of pregnancy

• when the breeding herd has access to other cattle on the property. 

Clinical signs

Clinical signs of pestivirus can vary depending on the strain of virus and time of infection.

Clinical signs that would lead you to suspect pestivirus include:

• early-term abortion or embryonic loss

• temporary infertility

• increased susceptibility to other diseases

• weak, stunted or deformed calves

• diarrhoea

• respiratory disease

• ill-thrift and wastage 

Mucosal disease is the most dramatic syndrome associated with BVDV infection and the syndrome most often recognised by producers. Affected cattle:

• drool excessively

• appear depressed and feverish

• have persistent and often bloody diarrhoea, a soft cough and lameness.

• These symptoms can easily be confused with foot-and-mouth disease, rinderpest, and malignant catarrhal fever.

Vaccination available: Yes

Leptospirosis

Leptospirosis occurs in cattle, sheep and goats. It is caused by bacteria called Leptospira and can lead to foetal abortions and stillbirths.

The disease is spread by urine from infected animals contaminating pastures, water and feed. Infected animals can carry the bacteria for a long time and may not display any clinical signs. It is a zoonotic disease that can infect humans. It is a workplace health and safety issue for farm workers.

Conditions when leptospirosis is likely to occur

• movement of infected animals into or among herds or flocks

• properties trading cattle, sheep or goats in conjunction with a breeding herd

• contact with certain wildlife, such as feral pigs

• previous history of leptospirosis on the property or in the herd or flock

• access to wet areas where the bacteria survive

• regions with a hot, humid climate

• farm workers and veterinarians handling animals shedding the bacteria.

Clinical signs in cattle

• abortion or still births

• decline in quality and quantity of milk

• bloody port wine coloured urine

• rough, dry coat

• severe fever and death in young animals

Vaccination available: Yes