Immune Ready is a guideline for the care of sale cattle.
This protects cattle in the preparation, transport and arrival post sale.

BE READY TO COMBAT THE MOST COMMON
INFECTIOUS DISEASES IN AUSTRALIA

CAUSE

In Australia there are 5 key Clostridial diseases that affect cattle. Enterotoxaemia (pulpy kidney), tetanus, black disease, malignant oedema and blackleg. Botulism is covered in a separate vaccine.

SPREAD

The bacteria associated with Clostridial diseases are widespread in the environment, are generally found in soil and can survive for a very long time through the production of spores.

CLINICAL SIGNS

The Clostridial diseases cause acute illness often resulting in rapid death. Even if clinical signs are recognised, treatment is usually not possible.

CAUSE

Leptospirosis is an infectious disease that results from the bacteria Leptospira spp. There are two significant types of Leptospira spp. in Australia affecting cattle – Leptospira borgpetesenii serovar Hardjo type Hardjobovis and Leptospira interrogans serovar Pomona.

SPREAD

The bacteria are predominantly spread in urine and placental fluid of infected animals. Pigs are also a reservoir of infection in Australia. Contact with floodwater and stagnant water is also known to spread leptospirosis.

CLINICAL SIGNS

Leptospirosis causes infertility, abortion, and the birth of weak calves. Importantly, leptospirosis affects humans. Vaccination of animals is a key step to preventing human infection.

CAUSE

Pestivirus, also known as bovine viral diarrhoea virus (BVDV).

SPREAD

Pestivirus is a highly contagious virus spread by nose-to-nose contact. It has been found throughout the entire Australian cattle population. The main source of infection is via persistently infected (PI) animals.

CLINICAL SIGNS

Pestivirus infection results in reproductive losses, the birth of persistently infected calves and immune suppression. The immune suppression associated with this disease causes infected animals to be more susceptible to other diseases such as bovine respiratory disease (BRD).

TESTING

Buyers and sellers should consult their veterinarian to discuss testing requirements necessary to answer NCHD questions 3 and 4.

3

– Antigen testing is used to identify carrier animals (persistently infected animals).

4

– Antibody testing is used to determine if a mob of cattle is considered has or has not been previously exposed to Pestivirus.

Bulls

– All bulls should be tested for Pestivirus antigen and NOT be persistently infected prior to sale (see question 3 and 4 of NCHD).

Breeding females

– Vaccination according to label directions reduces the risk of introducing heifers or cows pregnant with foetuses or with calves at foot that are persistently infected. Note that testing is required to detect if the dam herself is a PI (refer to question 3 on NCHD). Note that unborn calves cannot be tested prior to birth to determine if they are persistently infected.

CAUSE

Vibriosis is a venereal disease of cattle caused by bacteria Campylobacter fetus subspecies venerealis.

SPREAD

Vibriosis is spread during breeding either from an infected bull to an uninfected cow or vice versa. Infected bulls can act as carriers for many years. Female cattle may also carry infection into their next breeding period.

CLINICAL SIGNS

Vibriosis causes poor conception rates and abortions in females and reduces semen quality in bulls.

CAUSE

MH is a significant cause of bovine respiratory disease (BRD).

SPREAD

While the organism frequently lives in the upper airways of healthy cattle, stressors which often occur in cattle during weaning, transportation, and sale along with exposure to viruses including Pestivirus and IBR allow MH to invade the lungs and cause BRD.

CLINICAL SIGNS

MH causes non-specific clinical signs such as fever, anorexia, and depression. Respiratory signs such as abnormal or rapid breathing, nasal discharge or coughing, subsequently follow.

CAUSE

IBR is a herpes virus and is a significant cause of BRD.

SPREAD

IBR is highly contagious and is spread by close contact and aerosol. Many herds are affected by IBR. Routine cattle management practices like weaning, transportation and commingling exacerbates disease spread and severity.

CLINICAL SIGNS

Respiratory signs include abnormal or rapid breathing, nasal discharge and/or coughing. The herpes virus causing IBR is also associated with penile lesions causing reproductive failure in bulls, and vulva and vaginal lesions in breeding females.

CAUSE

Botulism is caused by a potent nerve toxin produced by the bacteria Clostridium botulinum.

SPREAD

Botulism is commonly seen in phosphorus-deficient areas and during droughts where cattle seek bones and carrion to satisfy a craving for phosphorus and/or protein. Cattle ingest the toxin while eating these materials. Outbreaks have occurred in dairies and feedlots where fodder has been contaminated with dead animals. Chicken manure spread on pasture has also been implicated in botulism outbreaks.

CLINICAL SIGNS

Animals suffering botulism show flaccid paralysis which invariable results in death. Early signs may include stiff gait and drooling of saliva.

CAUSE

Most calf scours are caused by infections with one or more of the following pathogens: Rotavirus, coronavirus, E.coli, Salmonella spp. and Cryptosporidium parvum.
Calves with inadequate colostrum intake are at increased risk of calf scours.

SPREAD

These organisms are transferred by the faeco-oral route. The main source of these infections is carrier cows, sick calves and the environment in which they reside.

CLINICAL SIGNS

The severity of diarrhoea can range from mild and self-limiting to life-threatening. Most calves which die from calf scours do so from dehydration. E.coli infections can result in sudden septicaemia and death. Rotavirus is the most frequently isolated calf scour pathogen in Australia and mixed infections often occur in calves.
Salmonella spp. are included in different vaccines and is discussed separately. No vaccine exists for Cryptosporidium parvum.

CAUSE

Salmonellosis is the disease caused by the bacteria, Salmonella enterica spp. which has over 2,000 different strains. Cattle are usually clinically infected by less than 10 of them. Strain typing is important in vaccine selection as there is minimal crossprotection between strains.

SPREAD

Salmonella spp. is a highly contagious bacteria that spreads primarily when animals consume contaminated feed or water. Salmonella spp. can infect birds and mammals, including humans. As a result, manure from infected birds, rodents and other wild animals is a common source for contamination of the environment, water and feed. Most bacteria are shed in manure, but when systemic illness develops, the bacteria are also shed in saliva, nasal secretions, urine, colostrum and milk.

CLINICAL SIGNS

Infections range from apparently “healthy” carrier animals to those that show acute and severe signs of illness. Calves with failure of transfer of passive immunity from colostrum are at highest risk of calf scour pathogens, including Salmonella spp. Clinical signs include rapid onset fever and dehydration, depression, anorexia, often foul-smelling diarrhoea which may or may not contain blood, mucus or shreds of intestinal lining. Death may occur in 24-48 hours. Milking cows may show a severe drop in milk yield and pregnant animals may abort.

CAUSE

One of the inciting organisms in Pink Eye is Moraxella bovis.

SPREAD

The bacteria are shed in ocular secretions, and cattle may be subclinical carriers. Transmission is by fomites, flies, aerosols, and direct contact. Other factors contributing to infection include ultraviolet light and trauma from dust or plant materials.

CLINICAL SIGNS

Pink Eye is more common during the summer months when there is increased UV exposure and fly activity. Young cattle with unpigmented eyelids are at increased risk. Signs include excessive tears, closure of the affected eye due to pain and variable abnormalities ranging from cloudiness to a yellow – or pink – filled eyeball.

CAUSE

BEF is caused by an insect-borne virus (BEFV) and is also known as “3-day sickness”.

SPREAD

The BEF virus is spread in the saliva of infected biting insects, commonly mosquitoes. It tends to occur seasonally within a geographic distribution (see map, page 5) and is more common during wet, warm summers.

CLINICAL SIGNS

BEF causes a high fever, stiffness and lameness due to inflammation of the blood vessels in the muscles, joints and skin. BEF causes major economic losses due to deaths, loss of condition and decreased weight gain. There is a significant drop in milk yield of affected dairy cows. Bulls are more susceptible to BEF and the disease can cause temporary infertility (up to 6 months) because of the high fever.

CAUSE

Tick fever is a disease of cattle caused by blood parasites Babesia bovis, Babesia bigemina or Anaplasma marginale.

SPREAD

These parasites are transmitted in the saliva of the blood-sucking ‘cattle tick’. Tick fever is endemic in the geographical areas associated with cattle ticks (see map, page 5).

CLINICAL SIGNS

Signs of tick fever vary depending on which organism is involved but includes weakness, depression, loss of appetite, weight loss, high fever, anaemia, jaundice, reduced bull fertility and potentially death. Dairy cattle do not have the same innate resistance to ticks and tick fever compared to some beef breeds. Disease occurs when cattle are introduced from tick-free areas or when locally bred cattle fail to acquire immunity from lack of exposure. Calves under 9 months rarely show signs due to colostral protection and innate resistance. However, this resistance wanes with age and disease is most severe in cattle 2-4 years old.

CAUSE

Johne’s Disease (JD) is a chronic bacterial disease caused by Mycobacterium avium subsp. paratuberculosis.

SPREAD

There are multiple routes of infection including faeco-oral, via infected milk and in-utero. The bacteria survive 12 months or more in favourable environments such as swampy or wetter farm areas. Calves are the most susceptible to infection by ingesting the bacteria in colostrum and milk from infected animals. There is a long period (2-5 years) between initial infection and evidence of clinical disease. Vaccination along with the industry tools Johne’s Beef Assurance Score (J-BAS) and the Johne’s Disease Dairy Score help mitigate the risk of buying cattle with JD.

CLINICAL SIGNS

JD is an untreatable fatal wasting disease of cattle, goats, alpaca, and deer. Signs include progressive weight loss, emaciation in older animals despite a good appetite, diarrhoea and bottle jaw.

CAUSE

Anthrax is a zoonotic disease caused by the bacteria Bacillus anthracis.

SPREAD

Anthrax is transmitted by ingesting spores from soil on contaminated properties. These spores can survive in soil for many years.

CLINICAL SIGNS

The primary sign of anthrax in grazing animals is sudden death, often with bloody discharges from the mouth, nose and anus.
Humans can be affected, usually by infection of open sores when handling infected carcasses, but anthrax can be fatal if the bacterial spores are ingested or inhaled.
Use of the vaccine is regulated and permission from the relevant State or Territory Government Department is required.

To learn more about how you can take advantage of the Immune Ready Guidelines, talk to your cattle vet, selling agent or rural reseller.

© 2024 The Australian Cattle Veterinarians, a special interest group of the Australian Veterinary Association. All Rights Reserved.