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Read about these conditions which can affect a single animal or a whole herd, and have a marked effect on milk production without obvious clinical signs.

Sudden drop in milk production

Conditions that may have a marked effect on milk production without obvious clinical signs. How many animals are affected?

Herd problem

A single animal

  • Acidosis

    Acidosis

    What to look for - ranges from serious acute disease to milder chronic form.

    Acute acidosis

    • Usually within 1 day of carbohydrate overload
    • May stop eating
    • May appear depressed
    • May be unstable if standing
    • Rumen is often distended (on left side)
    • Tapping left flank may produce splashing sounds
    • May have profuse diarrhoea with an offensive smell
    • May become dehydrated, lie down, and without prompt treatment, are likely to die

    Chronic acidosis

    • Usually a herd problem
    • Vague clinical signs
    • Loss of appetite
    • Intermittent diarrhoea
    • Lower milk production
    • Depression

    Cause

    Excess amounts of carbohydrate-rich foods such as grains or fruit. Rumen function is overloaded leading to increased acid in the rumen. Milder forms have a slower onset, but if not managed can lead to long term changes to the rumen.

    Animals likely to be affected

    Often seen in cows in early lactation. Typically seen after calving, especially in cows that have been fed on pasture during the dry period and the rumen has not had time to adapt to concentrate feeds.

    Other diseases with similar signs

    Confirming the diagnosis

    • Recent increase in consumption of grain or fruit
    • Test rumen fluid acidity (pH)

    Treatment

    Serious cases of acidosis need rapid treatment. In severe cases your vet can operate to remove the rumen contents and provide other supportive treatments to help get the rumen operating again and prevent infection.

    Less severe cases may respond to treatment with magnesium products given by stomach tube. Afterwards it is important to feed good quality hay and ensure that animals do not have access to water until the next day.

    Animals that have mild acidosis should be fed good quality hay and reduced amounts of concentrates. Watch them closely to ensure that any animals that are not improving can be treated more intensively.

    Risk factors

    • High carbohydrate feeds are not stored securely 
    • Cattle introduced rapidly to diets containing high proportion of concentrates

    Prevention

    When introducing cattle to concentrates monitor them closely and check the consistency of their manure.

  • 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 tick 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.

  • Babesiosis

    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 (œredwater)  
    - 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.

  • Bloat

    Bloat (frothy)

      

    What to look for

    • Animals are often found dead with a very distended abdomen
    • If found before death: distended abdomen on the left side between the last rib and the hip bone very distressed, difficulty breathing if untreated, may die quickly
    • Cows can also have less severe forms of bloat that may depress milk production

    Cause

    Consumption of young, rapidly growing legumes, clover or lucerne. Bloat is usually caused by eating pasture species that are growing quickly and contain low fibre levels. Consequently, animals produce less saliva production which makes them more susceptible to bloat. Under certain circumstances, feeding on these pastures can lead to build up of foam in the rumen that prevents animals burping to remove the gas produced in the rumen.

    Animals likely to be affected

    Heifers are more likely to die of bloat than older cows. There may be breed differences in susceptibility, with Jerseys and crossbred cattle being more susceptible.

    Other diseases with similar signs

    Other causes of sudden death.

    Confirming the diagnosis

    • Sudden death of animals with very distended abdomens (this is only useful in diagnosis if the animal has died recently because all animals will œblow up after death)
    • Recently introduced to pastures with a high clover or lucerne content
    • Characteristic foam in the rumen (but this only lasts for a few hours after death)

    Treatment

    1. Move animals from the toxic pasture to a pasture with lower levels of clover or lucerne
    2. Provide supplementary feed such as hay or silage
    3. Animals that are mildly affected can be treated with a bloat drench. In advanced cases of bloat it is often difficult to administer treatments that will reduce foam in the rumen.
    4. Seriously affected animals (having difficulty breathing, open mouth, tongue out) need immediate assistance to either reduce the foam or remove it. As a last resort, an incision can be made in the upper left flank to allow the foam to escape. While this approach may save the bloated animal it is essential to call your vet immediately to repair the wound and administer antibiotics to counter infection.

    Risk factors

    Overconsumption of young, rapidly growing legumes, clover or lucerne pastures

    Prevention

    Only introduce animals when their appetite has been partially satisfied with safe pastures, hay or silage. Limit grazing time and observe cattle closely to assess the risk and act quickly if animals start to show signs of bloat.

    Administer anti-foaming chemicals:

    • detergents such as the teric group of chemicals
    • anti-foaming agents (bloat oils) such as paraffin oil and tallow
    • rumen modifiers such as monensin

    Most anti-foaming chemicals are only effective for a relatively short time. The major challenge is to ensure that animals have a continual supply of the chemical in their rumen. Systems for maintaining a safe level of chemical in the rumen include:

    • drench twice a day
    • spray pastures with oil
    • mix the medication with feeds that delivered in the bail during milking
    • flank application of bloat oil - some animals do not lick the oil and are not protected
    • add detergents to drinking troughs
    • bloat blocks -“ limited success because not all animals will lick the blocks
    • bloat capsules - designed to stay in the rumen and slowly release monensin for ~ 3 months

  • Bovine Ephemeral fever

    Bovine Ephemeral Fever

    What to look for

    Usually occurs in summer and autumn in the subtropical region of Australia, but outbreaks can occur in southern NSW and northern VIC.

    • Animals suddenly lose their appetite, are depressed and may become very stiff
    • Lactating cows have a severe drop in milk production
    • Most animals make a rapid recovery within a few days, although some take weeks to recover

    Cause -“ an insect-borne virus

    The virus is not transmitted from animal to animal directly but carried by several types of mosquitoes that are prevalent in the subtropical region of Australia. In some years the prevailing winds carry these insects into southern NSW and even to Victoria.

    Classes of animals likely to be affected

    In the subtropical region BEF is most often seen in animals under two years of age but all ages can be infected, especially in regions where animals have little or no immunity.

    Confirming the diagnosis

    The nature of the outbreak is usually sufficient to allow diagnosis of BEF e.g. several animals are affected with fever and lameness and the initial cases recover in a few days. In areas where the disease does not often occur, laboratory testing may be required.

    Treatment

    There is no specific treatment for BEF, but affected animals usually recover in a few days. Animals that do not recover quickly will generally respond to good nursing and provision of shade, water and food.

    Risk factors

    - Weather conditions that spread the carrier mosquitoes from subtropical areas   
    - Introducing animals into subtropical regions from southern regions

    Prevention

    When conditions favour the spread of BEF, if may be desirable to vaccinate susceptible stock in areas where the disease occurs less frequently, if severe losses are anticipated. 

  • Facial Eczema

    Facial eczema

      

    What to look for

    • A sudden drop in milk production
    • Photosensitisation occurs about 10 days later when the skin becomes irritated
    • Cows will be restless and seek shade, lick affected areas and rub skin raw against hard surfaces
    • Weight loss due to liver damage
    • May develop diarrhoea

    Cause -“ a liver toxin from pasture fungus (Pithomyces chartarum)

    Animals ingest the toxin (sporidesmin) produced by a fungus that grows on moist, dead grass. This fungus is relatively widespread in dairy areas in Victoria but only grows under very specific conditions. Facial eczema only occurs when the climatic conditions are suitable for rapid proliferation and production of large numbers of toxic spores.

    Animals likely to be affected

    Lactating dairy cows. It is usually seen in autumn with small outbreaks occurring in Gippsland and, less frequently in other districts.

    Other diseases with similar signs

    Liver damage and photosensitisation caused by toxins from other plants such as perennial ryegrass, brassica crops and St John'™s Wort.

    Confirming the diagnosis

    Usually based on the clinical signs and high toxic spore counts in pasture. Blood tests can be used to confirm liver damage, and if an animal dies, post mortem examination of the liver will show characteristic changes.

    Treatment

    Once the animal has liver damage there is no specific treatment, but the severity of the disease can be reduced by keeping animals in shade during the day and supporting them with anti-inflammatories, pain relief, good nursing, food and water. Most affected animals will recover but are likely to have reduced milk production. In some cases, the liver damage will be too severe for full recovery and these animals will be vulnerable to future outbreaks.

    Risk factors

    • Climatic conditions when the toxic fungus is likely to multiply to dangerous levels - a succession of moist warm evenings in autumn  
    • Animals grazing pasture containing a substantial amount of dead material
    • Previous exposure to toxins that cause liver damage

    Prevention

    Pasture spore monitoring is indicated when conditions are favourable for fungal production of sporedesmin. If pasture spore counts identify dangerous conditions, keep animals off pastures that contain high levels of moist dead pasture and consider feeding zinc supplements to protect animals from toxicity.

    More information

    Preventing facial eczema in milking cows using zinc oxide in feed (PDF, 231KB)

    Zinc supplements can be effective for facial eczema control and prevention if well managed. This resource includes a checklist for zinc oxide supplementation in feed.

    Dairy Australia's Facial Eczema spore monitoring program in Gippsland

  • Infectious Bovine Rhinotracheitis

    Infectious bovine rhinotracheitis

      

    What to look for

    Varies from outbreaks of mild disease through to severe illness.

    • Respiratory signs and fever
    • Clear discharge from their nostrils which may become cloudy and profuse
    • Drop in milk production
    • Inflamed eyes
    • Ulcers in the mouth
    • Laboured breathing
    • Not fatal unless there are complications such as bacterial infections

    Cause

    Herpes virus.

    Animals likely to be affected

    Most often seen as an outbreak in two year old cows but can occur in any age group. Outbreaks may be triggered by stressful situations such as transport or crowding.

    Other diseases with similar signs

    BVDV/Mucosal disease.

    Confirming the diagnosis

    Virus can be isolated from swabs of infected animals. Two blood samples collected several weeks apart can be tested to see if the level of antibodies to IBR increases.

    Spread of the disease

    The IBR virus is usually passed from cow to cow without causing disease. If a group of animals that have not previously encountered the virus and are stressed by such things as transport or introduction to the dairy herd an outbreak may occur. Animals usually stay infected with the virus for life and can spread it to animals that have not previously been exposed.

    Treatment

    Treatment is usually not required unless animals are seriously ill. If so, they should be isolated, given good nursing support and anti inflammatories. If bacterial infections are suspected, treat animals with antibiotics.

    Risk factors

    • Introducing cattle from outside the herd
    • Transportation, overcrowding or other stresses

    Prevention

    Maintaining a closed herd reduces the risk of introducing IBR virus but the virus is widespread in cattle populations and may be present in herds without clinical disease. If an outbreak occurs, isolate infected animals to reduce the spread of the virus to vulnerable animals. Vaccines can be used to if there is reason to believe that animals are vulnerable to IBR e.g. entering a feedlot. 

  • Ketosis

    Ketosis

    What to look for -“ can cause a range of signs

    Wasting form:

    • Rapid loss of condition 2 -8 weeks after calving
    • Drop in milk yield
    • Poor appetite
    • Breath smells strange (like acetone) due to the presence of ketones

    Nervous form:

    • Incoordination
    • Strange behaviour e.g. sucking items in the environment, wandering aimlessly
    • May become aggressive

    Cause

    Ketosis usually occurs in early lactation when there is a huge increase in energy requirements for milk production and animals are unable to produce enough glucose. It can also be triggered at any time by another problem that causes inadequate feeding and/or a disturbance in metabolism, a condition known as secondary ketosis.

    Animals likely to be affected

    Cows in early lactation (from 2 to 8 weeks after calving). Occurs most often in cows in their 3rd to 6th lactations, but can occur in animals of any age if their diet is inappropriate or they are suffering from another serious illness.

    Other diseases with similar signs

    Any diseases that cause sudden weight loss and/or nervous signs e.g. grass tetany, lead poisoning, displaced abomasum or infections in internal organs.

    Confirming the diagnosis

    A simple urine or milk test can detect ketones but will not determine if the ketosis is secondary to another disease. Diagnosis of any underlying condition is important in these cases. Consult your vet to undertake an assessment of the animal and recommend appropriate action.

    Treatment

    Treatment of any underlying condition is important. To correct the energy imbalance, the aim is to increase blood glucose levels and provide nursing support for the animal over the next few days. Drenching with propylene glycol or glycerine may be useful, but drugs generally need to be injected into the vein so consult your vet as soon as ketosis is suspected.

    Risk factors

    • Inadequate feed supply in early lactation
    • Poor appetite caused by lameness, mastitis or other conditions
    • Unpalatable feed or poor quality silage
    • Left displaced abomasum

    Prevention

    Ensure that animals are well fed especially during the latter part of the dry period and in the early stages of lactation. Good feed management during the transition period will also reduce the risk of other diseases such as milk fever and grass tetany and improve production during the entire lactation.

    More information

    Transition feeding with limited effective fibre (PDF, 281KB)

    Around calving, the dairy cow undergoes a dramatic transition from dry and heavily pregnant to fully lactating. This is a stressful period for the cow and she is vulnerable to many problems and disorders that can affect her health and productivity. Feeding during the last 2-3 weeks before calving not only determines what happens to body condition at this time, but also provides an opportunity to prepare the cow for the coming lactation. Find out what you can do, including management tips and pre-calving diets with low DCAD. 

  • 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 (red 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

    • œRed 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.

  • Malignant Catarrhal fever

    Malignant catarrhal fever

    What to look for

    There are 2 different forms of the disease.

    Head and eye form:

    • Usually occurs in single animals
    • Sudden onset of fever, depression, lack of appetite
    • A big drop in milk production in lactating cows
    • Copious discharges from the nostrils, red nose and cloudy eyes
    • May develop ulcers in the mouth
    • Affected animals generally die within a few days

    Gut form:

    • May affect individual animals or occur as an outbreak
    • Much milder changes to the nostrils, eyes and mouth seen
    • Animals rapidly develop profuse diarrhoea and die quickly

    Cause

    Virus normally found in sheep without causing clinical signs of disease.

    Spread of the disease

    Most sheep are infected with the virus which is secreted in their nasal secretions. It is not clear how cattle become infected but the disease rarely occurs in cattle that do not have contact with sheep. Some cattle appear to become infected without showing any clinical signs but it is believed that there is no transfer of MCF virus between cattle.

    Animals likely to be affected

    Malignant Catarrhal Fever is an unusual condition that is most often seen in yearling animals. Wild and domesticated deer are also susceptible.

    Other diseases with similar signs

    May resemble some forms of Bovine Virus Diarrhoea mucosal disease (caused by bovine pestivirus) or exotic diseases such as Foot and Mouth Disease.

    Confirming the diagnosis

    Any suspected case of MCF should be investigated by your vet to rule out the possibility of the Foot and Mouth Disease or other similar diseases that do not occur in this country.

    Treatment

    There is no treatment for MCF and so infected animals should be humanely killed.

    Risk factors

    Running sheep and cattle together. There is no vaccine for MCF and no specific preventive measures.

     

  • 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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