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Learn about conditions that cause abortions in early or late pregnancy or a high rate of empty cows.

Abortion and infertility

Conditions that cause abortions in early or late pregnancy or a high rate of empty cows. What is happening?

Single cow abortion

  • Listeria
  • Q fever
  • Trauma
  • Genetic factors
  • Any kind of fever or serious disease

Multiple abortions in the herd

Cows failing to conceive

For more information about fertility see the InCalf section of this website.

  • Akabane virus

    Akabane virus

      

    What to look for

    • Abortions, stillborn & deformed calves
    • The type of deformity varies with the age of the foetus when it was infected the brain is the main site in earlier pregnancy and the legs and joints can be affected in later pregnancy.
    • No signs of illness in adult cattle

    Cause an insect-borne virus

    Akabane virus is carried by biting midges called Culicoides, which range over large regions of tropical and sub-tropical Australia. Cattle in this area are regularly exposed to akabane virus, leading to a high level of immunity. Problems occur when Culicoides midges spread into areas where Akabane virus has not appeared for a number of years, so the cattle population has little immunity. If cows are 3-6 months pregnant when infected multiple cases of abortions, stillbirths and deformed calves may occur.

    Animals likely to be affected

    Pregnant animals < 2 years old.

    Other diseases with similar signs

    Other causes of abortion and stillbirth. Other causes of deformity in calves exist, which are sometimes very hard to diagnose.

    Confirming the diagnosis

    Tests on foetal fluids or the blood of the dam, together with a history of Culicoides midges in the area when the cows were in mid-pregnancy.

    Risks to people

    No direct risk however abortions in cattle are caused by a number of other infections, some of which cause diseases in people, so pay close attention to personal hygiene if handling aborted calves or their mothers.

    Treatment

    Treatment is not necessary. Cows that have been infected with the virus become immune and can be expected to have normal fertility in future (unless a major intervention was needed to deliver an aborted calf).

    Risk factors

    • Abnormal weather conditions favouring spread of Culicoides midges
    • Introducing pregnant animals from southern regions into areas where Culicoides midges are active and carrying Akabane virus.

  • Anaplasmosis

    Anaplasmosis (tick fever)

    Tick fever occurs only where cattle ticks are found, in the subtropical and tropical regions of Australia. Cattle ticks should not be confused with bush ticks which are found over a much wider area. There are several forms of tick fever. The disease discussed here is caused by an organism called Anaplasma. Babesiosis is another important œtick fever caused by two organisms called Babesia bovis and Babesia bigemina.

    What to look for“ most cases are mild

    • Anaemia - paleness of the lining of the mouth and the udder
    • Jaundice - yellowish tinge to skin and mucous membranes
    • Fever and a drop in milk production
    • Laboured breathing or cattle get out of breath easily when moved
    • Pregnant cows may abort
    • Occasionally fatal Cause a tick-borne protozoa
    • Anaplasma marginale belongs to the protozoa group of organisms.
    • Cattle become infected with Anaplasma when bitten by cattle ticks.
    • Anaplasma penetrate into red blood cells, multiply and destroy the red blood cells.
    • Animals usually stay infected for long periods (possibly for life) but may not show any signs of disease.

    Animals likely to be affected

    Animals can be infected at any age but, especially in young animals, the disease may not be obvious. The most severely affected animals are usually mature lactating cows.

    Other diseases with similar signs

    Other conditions that cause depression and anaemia in sub-tropical regions e.g. copper poisoning, bracken fern and other plant poisonings, Babesiosis. It is unusual to see blood in the urine whereas this is a common sign of Babesiosis and bracken fern poisoning.

    Confirming the diagnosis

    Laboratory examination of blood smears

    Spread of the disease

    Cattle ticks (especially Rhipicephilus microplus)

    Treatment

    Antimicrobial injections can improve the condition of seriously infected animals.

    Prevention 

    • Expose young animals (< 9 months of age) to tick fever organisms in areas where tick fever occurs.
    • Early exposure is unlikely to cause clinical signs of infection and may provide immunity for several years.
    • Control ticks reducing the number of ticks reduces the chance of animals becoming infected with tick fever.
    • Vaccinate non-exposed animals that are being introduced into areas where tick fevers occur.
    • Vaccinated animals should be closely observed 1-3 weeks after vaccination as some animals may have a bad reaction.

  • Cattle ticks

    Babesiosis (tick fever)

    Tick fever occurs only where cattle ticks are found, in the subtropical and tropical regions of Australia. Cattle ticks should not be confused with bush ticks which are found over a much wider area. There are several forms of œtick fever. The disease discussed here is caused by organism called Babesia bovis and Babesia bigemina. Anaplasmosis is another important œtick fever caused by an organism called Anaplasma.

    What to look for

    Signs range from minimal illness to severe disease and death:

    - Red urine (redwater)
    - High fever and a drop in milk production
    - Nervous signs
    - Diarrhoea
    - Anaemia and jaundice

    Cause infection with a protozoan organism

    Babesia must complete part of their life cycle outside cattle, and are transmitted from animal to animal by cattle ticks (especially Rhiphicephilus microplus). Adult ticks draw in Babesia organisms when sucking blood from cows. The ticks then drop off the cow and lay eggs which hatch in the environment. Immature ticks harbour Babesia organisms in their salivary glands ready to be injected when they start to suck blood from a cow. Once injected into cattle they multiply inside red blood cells and then burst out of the cells. If this process continues for some time animals can become anaemic. Cows usually start to show signs of illness 2 weeks after they become infected. Cows can remain infected with Babesia for several years.

    Animals likely to be affected

    Tick fever is unusual in animals under 9 months of age. British breeds of cattle are more likely to be infected than Bos indicus breeds.

    Other diseases with similar signs

    In sub-tropical regions tick fever can be confused with other conditions that cause depression and red water, for example, copper poisoning, bracken fern and other plant poisonings. While anaplasmosis may resemble tick fever, affected animals rarely have blood in their urine.

    Confirming the diagnosis

    Examination of blood smears in a laboratory

    Treatment

    Your vet can prescribe drugs that treat sick animals and also provide protection for several weeks.

    Prevention

    The 3 main approaches to controlling the impact of tick fever:

    • Control tick numbers
    • Expose young animals to tick fever organisms when they are less than nine months of age. These animals are unlikely to show clinical signs of infection and can be expected to remain immune for several years.
    • Vaccination. Some animals may have a bad reaction 1-3 weeks after vaccination so observe recently vaccinated animals closely and promptly treat any that show signs of disease.

  • Campylobacter

    Campylobacter

    Campylobacter infection causes a venereal disease in cattle, previously known as vibriosis. (Not the same organism that commonly causes campylobacteriosis diarrhoea in people).

    What to look for

    • Cow infertility
    • Large number of naturally mated animals return to service at variable intervals after mating
    • Occasionally see abortions of foetuses after 2 to 5 months of pregnancy

    Cause

    Bacterial infection (Campylobacter fetus). C. fetus infects the penis and prepuce of bulls and the reproductive tract of cows.

    Animals likely to be affected

    Bulls become infected by mating with an infected cow. Young bulls (< 3 years of age) usually become free of the infection within 1-2 months, but older bulls tend to stay infected.

    Heifers and cows are infected after service by an infected bull and may remain infected for a few months or longer in some cases. While infected females can become pregnant, the infection may cause abortion in the first months of pregnancy and may not be noticed.

    Other diseases with similar signs

    Other venereal diseases are rare in the Australian dairy herd. Non-specific factors can cause early abortions but, usually affect one or, at worst, several animals.

    Confirming the diagnosis

    Laboratory testing of samples from bulls or fresh aborted foetuses. Samples may be taken from the penis and prepuce of bulls, or a fresh aborted foetus.

    Spread of the disease

    Campylobacter fetus infection is a venereal disease that is readily spread by bulls serving cows.

    Risks to people

    No direct risk, but other organisms that cause abortion in cattle can cause serious disease in people. Therefore use good hygiene when handling cows that have aborted.

    Treatment

    If you suspect campylobacter infection on your farm or in introduced animals, the most effective way to stop losses is to ask your vet to develop a vaccination program tailored to your situation.

    Risk factors

    • Natural mating rather than artificial insemination
    • Introducing bulls of unknown status. Bulls that have not previously been used or have been vaccinated should be safe. Other bulls should be tested prior to use.

  • Cypress poisoning

    Cypress poisoning

    What to look for

    • Abortions in the last third of pregnancy or birth of stillborn or very weak calves
    • Cows affected by cypress poisoning very often have retained foetal membranes

    Cause: a toxin in cypress tree fronds (usually Cupressus macrocarpa)

    If cows in late pregnancy eat branches of cypress trees, the fronds may contain a toxic substance that reduces blood flow in the uterus and causes abortion or limits growth and viability of the unborn calf. Wilted branches are more toxic than fresh material. Pine needles from some varieties of pine trees can also have the same effect.

    Animals likely to be affected

    Cows in the last third of pregnancy.

    Confirming the diagnosis

    Diagnosis is usually confirmed by observing cows eating cypress fronds. There are no routine laboratory tests to confirm cypress poisoning but there are tests for other causes of late abortions. If there is no obvious history of animals eating cypress fronds, consult your vet to arrange for laboratory testing of aborted material.

    Spread of the disease

    The disease is caused by eating cypress branches and does not spread from animal to animal.

    Treatment

    There are no specific treatments to reverse the effect of the toxin. Losses may continue for several weeks after the cows have ceased eating cypress fronds.

    Risk factors

    Allowing cows in late pregnancy, to have access to cypress trees (and pine trees).

  • Leptospirosis

    Leptospirosis

    What to look for

    Infected animals often do not show any clinical signs
    NB - leptospirosis can cause a very serious flu-like condition in farm workers

    Acute disease in calves:

    • High temperatures
    • Red coloured urine
    • Poor appetite and, in some cases death

    Adult cows:

    Abortion usually in the latter half of pregnancy (foetus may be mummified)
    Even if the infected animals do not show any signs of infection they can still be excreting organisms in their urine.

    Cause

    A bacterial infection (Leptospira). The two most important types of the Leptospira in cattle in Australia are hardjo and pomona. These organisms reside in the kidneys of infected animals for long periods (weeks or months) and are passed out in urine, which can remain infectious for weeks in moist conditions.

    Animals likely to be affected

    Calves

    Calves may experience an acute infection that spreads readily and is characterised by red urine (œred water), high temperatures, poor appetite and, if not treated promptly, can lead to death.

    Adult animals

    Occasionally, adult animals will develop a disease similar to that described for calves. Usually the infection causes no clinical signs, unless they are pregnant, when it may lead to abortion.

    Other diseases with similar signs

    Red water can also occur in tick fever or poisoning by kale or rape, or phosphorus deficiency.
    Other causes of abortion require a thorough disease investigation.

    Confirming the diagnosis

    Diagnosis requires identification of the Leptospira organisms in urine of infected animals or aborted foetuses. The Leptospira organism is hard to isolate in the laboratory and sometimes the diagnosis can be confirmed by showing a rise in Leptospira antibodies in blood samples taken during the course of the outbreak.

    Spread of the disease

    Animals become infected via pasture or bedding that has been contaminated by urine from infected animals, which may appear healthy but are secreting Leptospira in their urine.

    Risks to people

    People can contract Leptospirosis by contact with urine from animals that have the disease but may not be showing any signs of illness. Leptospirosis can make people very ill for weeks or months. There is currently no vaccine available to protect people against this disease.

    Treatment

    Antibiotics are effective. Consult your vet regarding the best form of treatment.

    Risk factors

    • Failure to vaccinate young stock with a lepto vaccine
    • Inadequate vaccination - calves require two doses of vaccine six weeks apart early in life, followed up by booster doses

  • Listeria

    Listeria

      

    Listeria and Humans

    Listeria is common in the environment and poses a particular risk to vulnerable groups of consumers e.g. the elderly, the very young, pregnant women and those with compromised immune systems), so very strict control measures are followed to ensure Listeria species do not contaminate dairy products.

    Listeria and livestock

    What to look for 

    • Nervous signs - paralysis of muscles, restlessness and/or walking in circles
    • Fever
    • Pregnant cows may abort
    • Death may occur within 2-3 days

    Cause: a bacterial infection (Listeria monocytogenes)

    Listeria can cause serious disease in a wide range of animal species and in humans, but rarely causes illness in cattle. This bacteria is widespread in the dairy environment (in soil, water, feed) and survives in a wide range of conditions including poorly made or spoiled silage. There are no simple tests to identify feed that is contaminated by Listeria.

    Animals likely to be affected

    Listeriosis can infect cattle of any age but is most often seen in young adult cattle. It rarely infects animals under six months of age. If several animals have access to the same contaminated feed source there may be an outbreak of Listeria, but the disease does not generally spread from animal to animal.

    Other diseases with similar signs

    Other causes of abortion or nervous signs.

    Confirming the diagnosis

    A post-mortem examination will allow your vet to collect brain samples that can be examined at a laboratory for the characteristic changes caused by Listeria.

    Risks to people

    Most Listeria infections in humans result from eating contaminated food, but it is very important that people practice good personal hygiene when handling sick or dead animals.

    Treatment

    Antibiotics and other supportive therapies can be useful if Listeria is detected early.

    Risk factors

    • feeding poorly made or spoiled silage
      

  • Neospora

    Neospora

    What to look for

    • Abortions, multiple or single animals affected
    • Cows are usually in mid-pregnancy
    • The dead calf may be retained in the cow and become mummified
    • Calves might be born alive but weak

    Cause - a protozoan organism (Neosporum caninum)

    Domestic dogs (and possibly foxes) are the natural hosts, and can be persistently infected without any signs of illness. The parasite is deposited into the environment in dog faeces where it may be picked up by cows. It then spreads through the body tissues including the foetus. The organism may also spread from cow to cow, possibly by contact with newborn calves or afterbirth. A proportion of calves that are infected before birth are born healthy, but remain infected with Neospora organisms, and are likely to infect their own calves when they become pregnant.

    Animals likely to be affected

    Pregnant cows.

    Other diseases with similar signs

    Other causes of abortion.

    Confirming the diagnosis

    Characteristic microscopic changes in the aborted calf. Blood samples from cows that have aborted and from other animals in the herd may also help determine the cause of the abortion. Many infected animals are healthy and show no signs of infection.

    Risks to people

    Neosporum caninum does not infect people but other agents that cause abortions in cattle such as ListeriaLeptospirosis and Salmonella can cause serious diseases in people. Treat all aborted calves and the associated afterbirth as infectious and take care with personal hygiene to minimise exposure.

    Risk factors

    • Dogs have access to areas where cows are feeding
    • Persistently infected cows

    Prevention

    Use a blood test to identify cows that are infected and either cull them or only use cows that are blood test negative for breeding future replacements. Embryo transfer may also be used to breed uninfected calves from infected mothers if the infected cow has a high genetic value.

  • Nitrate poisoning

    Nitrate poisoning

    What to look for

    • Sudden death in a number of animals
    • Animals found alive are depressed, have difficulty breathing and are uncoordinated
    • Abortion may occur in pregnant cows weeks after they are exposed to toxic levels of nitrate T
    • he blood of recently dead animals is a brownish colour

    Cause - rapid build up of nitrate in the rumen

    Nitrate is a normal component of plants and is usually converted in the rumen to nitrite which is, in turn, changed to ammonia. If nitrate levels in plants are higher than usual and/or the conversion of nitrite in the rumen is too slow, nitrate concentrations in the rumen can build up to toxic levels. Excess nitrate is absorbed into the bloodstream where it binds with haemoglobin and reduces the ability of the blood to carry oxygen.

    Nitrate can build up in many plants including pasture species such as rye grass, fodder crops such as millet or brassica, or weeds such as capeweed.

    Build up is most likely to occur when:

    • the weather is overcast.
    • plants are having a spurt of growth following a period of stress.
    • if nitrogenous fertilizers have recently been spread on the pasture

    Animals appear to be able to adapt to higher levels of nitrate and this can be assisted by providing some roughage such as hay when animals are grazing lush pastures.

    Other diseases with similar signs

    Any disease that causes sudden death such as anthrax, bloat, enterotoxaemia (pulpy kidney) or milk fever can be confused with nitrate poisoning.

    Confirming the diagnosis

    Consider nitrate poisoning when the disease outbreak involves a number of animals that have been on potentially toxic pastures, and the blood of recently dead animals is a brownish colour. Your vet can test blood, urine or fluid from inside the eye for the presence of methaemoglobin. Plants can also be tested for nitrate, but care is needed to interpret the results.

    Treatment

    If you suspect nitrate poisoning quietly move the remainder of the mob to a paddock that has less toxic pasture and provide alternative feed such as hay or silage. If sick animals are identified early it is possible for your vet to treat them with methylene blue injections.

    Risk factors

    • Grazing of lush pastures, especially, if cattle have access first thing in the morning or the conditions are overcast
    • Introducing hungry animals to rich pastures without access to roughage, particularly following a period of stress
    • Recent application of nitrogenous fertilizers

    Prevention

    • Check pasture nitrogen levels before grazing 
    • Strip graze high risk pastures
    • Pre-feed hungry cattle with hay prior to grazing high risk pastures
    • Wait for sunny conditions to reduce pasture nitrate levels

  • Q fever

    Q fever

      

    Clinical signs

    Q fever very rarely causes any signs of clinical disease. Rarely the Q fever organism will cause abortion in cows, sheep and goats. This disease is significant because it can cause serious illness in people.

    Cause“ a bacterial infection (Coxiella burnetii)

    Infected animals shed the organism in urine, milk, faeces and placental fluids. Contact with foetuses and foetal membranes from aborted animals can expose individuals to high doses of infective material. The Q fever organism is very tough and can survive for months in the environment.

    Animals likely to be affected

    Cattle can be infected at any age and can remain infected for months or years.

    Confirming the diagnosis

    Blood tests can determine if animals have been infected with the Q fever organism. Other laboratory tests are usually required to sort out the cause of abortion in cattle.

    Spread of the disease

    Animals are infected with the Q fever organism by inhaling or ingesting infected material such as urine, milk, faeces or after-birth from infected animals. People are infected most frequently by inhaling infected material from these same sources or from environmental contamination. Wind borne transmission of the organism in dust is an important source of infection.

    Risks to people

    It is very easy for people to catch Q fever. It can cause a prolonged fever and headaches and some people develop serious symptoms involving the lungs, liver, heart or brain. About 10% people that are seriously ill with Q fever do not return to normal within 12 months. People who have close contact with farm animals such as farm workers, vets, abattoir staff and livestock agents carry the greatest risk of contracting Q fever. Abattoir workers are at risk of infection when working on pregnant animals. Farmers need to use care when assisting at calvings and avoid direct contact with afterbirth materials. Aborted foetuses and afterbirth should be disposed of safely by burning.

    Treatment

    Animals with Q fever are not treated, but if people become infected it is important that they receive prompt medical attention to relieve symptoms and avoid serious complications.

    Prevention

    A vaccine is available for people who are in close contact with farm animals and it is recommended that all dairy farmers and their staff are vaccinated.

    More information

    Some useful websites with Q Fever information include:

    www.health.gov.au

    http://ideas.health.vic.gov.au

  • Salmonellosis

    Salmonellosis

    What to look for

    • Fever and depression
    • Foul smelling diarrhoea which may contain shreds of intestinal lining and/or blood
    • Rapid dehydration, weight loss
    • High death rate in calves
    • Abortion in pregnant animals

    Cause:“ a bacterial infection (various Salmonella species)

    Salmonella infections occur in a huge range of animals, birds and reptiles, and can move from one animal species to another. It is often carried in the gut of animals and birds without causing disease. Contamination of feed stuffs and water with faecal material can cause large scale outbreaks. Outbreaks are sometimes related to stresses such as transport, temporary deprivation of feed or sudden onset of extreme weather events. The number of infected animals can vary from isolated cases to outbreaks involving large numbers of animals.

    Animals likely to be affected

    Most commonly seen in young calves (2-6 weeks of age) and lactating cows with high milk production.

    Other diseases with similar signs - other causes of severe diarrhoea

    In young animals (see Chapter 7 of Rearing Healthy Calves) these diseases include infection with rotavirus, cryptosporidia, Escherichia coli, coccidiosis, bovine viral diarrhoea, roundworms or Yersiniosis. In older animals you also need to consider conditions caused by trace element deficiencies (copper or selenium), plant toxicities or poisonings.

    Confirming the diagnosis

    The diagnosis is based on clinical examination, a thorough history of an outbreak and laboratory testing. Farmers that have experienced an outbreak of salmonellosis in adult cattle will be able to quickly recognise the clinical signs and should seek early assistance.

    Spread of the disease

    Salmonella can spread by movement of animals or by spreading of effluent on pastures. It can persist for months in a cool and moist environment and contamination can build up relatively quickly when an animal develops diarrhoea and excretes huge numbers of the organism. Prompt treatment and isolation of sick animals is therefore paramount.

    Risks to people

    Salmonella is one of the most important causes of gastroenteritis in people. Most cases occur after consumption of contaminated food but infection can be contracted directly from animals especially if they have clinical salmonellosis. In these circumstances it is very important to reduce exposure as much as possible and to practice high levels of personal hygiene. Do not drink unpasteurised milk from cows that may be infected with Salmonella.

    Treatment

    Cows and calves with serious cases of salmonellosis will deteriorate very quickly. Call your vet as quickly as possible to get a diagnosis and start appropriate treatment. They require prompt treatment with antibiotics and supporting therapy to save lives and slow spread of the disease.

    Risk factors

    • introducing animals that have been mixed with animals of unknown origin, especially in stressful environments such as saleyards
    • introducing animals to the main herd before there has been time for any sick animals to identified
    • contact between susceptible animals and effluent on the home property or from neighbours
    • mixing agisted animals with other animals or transporting them in dirty trucks rodent infestations

    Prevention

    A vaccine is available that cattle protects against the most important strains of salmonella found in Australia. It requires two doses about a month apart with an annual booster. Passive immunity in young calves can be boosted by feeding an adequate amount of colostrum from vaccinated cows in the first few hours of life.

  • Theileriosis

    Theileriosis

    What to look for

    • Usually seen recently after cattle have been introduced to a herd.
    • Abortions in late pregnancy or stillborn calves
    • Anaemia and jaundice (pale or yellowish mucous membranes)
    • Cattle get out of breath easily when moved
    • Production losses
    • Poor appetite, weakness and depression
    • Occasional deaths

    Cause - a blood parasite (Theileria)

    This parasite is transmitted by bush ticks (Haemaphysalis) but may also spread by multiple use of vaccination guns, ear taggers or other husbandry devices that are contaminated with blood. Theileria is widespread in Queensland and Northern NSW and has been found in all states except South Australia and Tasmania. In herds where the parasite is established there is usually little evidence of disease unless animals are introduced that have not previously encountered the parasite. Once animals are infected they are likely to remain infected for life.

    Animals likely to be affected

    Cows in late pregnancy or early lactation. Outbreaks usually follow the recent introduction of new animals to the herd.

    Other diseases with similar signs

    Other causes of anaemia include Brassica poisoning (kale anaemia); Pimelia poisoning (St George disease); bacillary haemoglobinuria; leptospirosis in calves; post-parturient haemoglobinuria (hypophosphataemia); chronic copper poisoning and snake bite. In tropical and subtropical areas, tick fever and anaplasmosis should be excluded.

    Confirming the diagnosis

    Laboratory tests can confirm the presence of a specific type of anaemia and can demonstrate the causative parasite in blood smears.

    Prevention

    Prevention of Theileria is difficult once it is established in the local bush tick population. However you can reduce the risk of introducing this parasite to your farm by good biosecurity measures. Infected animals may not show any signs of disease so it pays to seek veterinary advice if planning cattle movements to or from areas where the disease occurs. Avoid introducing infected animals into if your herd is free of the infection, especially if cows are in late pregnancy.

    Risk factors

    • Introducing pregnant animals that are free of Theileria to an infected herd
    • Introducing infected animals into herds that are free of the infection

    Treatment

    No specific treatment is available, so good nutrition and nursing care is the best option.

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