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Some of these insecticides may cause temporary irritation to the animals, and it is essential that the
producer always reads the label of the product carefully to determine the method of treatment, potential side
efects to the animal and operator, and mandatory withholding periods and export slaughter intervals.
Moreover, records of all animal treatments must be kept by the producer that includes this information, and
also the batch number and date of application of the treatment.
Ringworm This is a highly infectious fungal disease and afects the
outer layers of the skin. It occurs mainly in young animals and once infected, the animal develops immunity and
will not be re-infected Fig. 4.26. Signs of the disease include crusty skin lesions that start as small scaly
patches and slowly enlarge. It is most often seen on the head and neck - lesions persist for several months then
heal completely, and in very thin or diseased animals the ringworm scabs may persist longer. Ringworm can also
be present at the same time as a lice infestation as both thrive under the same conditions.
Treatment of cattle for ringworm involves isolating the infected animals as they will pass the disease onto
others. The afected areas can be treated by scrubbing with soap and water and then bathing the area with a
1 solution of tincture of iodine for 3 to 7 days. It should be remembered that this disease can be passed onto
humans, thus protective clothing such as gloves should be worn while treating and handling afected animals.
4.5.2. Internal Parasites
These parasites can generally be grouped into two main types; round worms or lat worms. Some of these
parasites may spend their entire life cycle in the cattle while others spend a part of their life cycle in other hosts
for example, snails in the case of the liver luke. Young animals, and animals in poor condition or
poor health are particularly vulnerable to any parasite or disease as their natural immune system is not fully
efective to resist the disease challenge. Conversely, adult animals in good condition and on good feed
can tolerate higher parasitic infestations than poorer conditioned animals or calves.
Figure 4.26. Ringworm on the head and neck of a Friesian heifer. Source: Meat and Livestock Australia.
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Beef Breeder MANUAL
Most internal parasites are spread by cattle depositing the eggs on the ground in their dung. The eggs then
hatch and contaminate the pasture or feed Fig. 4.27.
With some worm types the eggs have to be eaten and they then hatch inside the animal. Generally most
worm eggs hatch on the pasture. This is then eaten by
Figure 4.27. Infective third stage larvae of nematodes suspended on grass in a drop of dew. Source: Merial Australia.
Figure 4.28. Life cycle of Liver Fluke. Source: Pizer Animal Health.
the cattle foraging for food. Any feed that is harvested for cattle should be fed in a trough of the ground to
reduce the spread of worms.
Life cycles of Liver Fluke and gastro-intestinal round worms are shown in Fig. 4.28 and 4.29.
Mud Snail Miracidia
Metacercariae on grass
Eggs eggs shed a
minimum of 12 weeks after
infection
Cercariae 5-7 weeks
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Cold Winter Climates
Figure 4.29. Life cycle of gastro-intestinal roundworms.
Symptoms Symptoms may not become evident until the worm
infestations become heavy. Signs to look for are: • Poor or skinny animals - or loss of weight
• Rough or dry coat the hair becomes harsh to touch and stands up
• Diarrhoea which may be foul smelling • Bottle jaw - swelling under the jaw caused by luid
build up • Eggs in the dung
• Death in acute cases. Treatment
Treatment for internal parasites is generally by drenching with chemicals or by pouring a chemical along the back
of the animals.
Insecticidal pour-on is easy to apply and will last for up to three weeks for both internal and external parasites.
It is essential that the producer has the type and extent of the parasitic burden identiied so that the correct
treatment can be given.
Incorrect treatment will only lead to increased levels of infestation and resistance to chemicals, which will make
it more diicult to control them in the future.
Larvae in wall of
abomasum EITHER develop directly in 3-4
weeks Adult
worms in abo-
masum Development
of larvae in late spring summer is arrested
for several months OR
Infected larvae swallowed Eggs passed in
dung Infected larvae
eaten in water droplets on grass
L3 larvae on grass
L1, L2 L3 larvae in dung pat
Eggs in dung pat
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Beef Breeder MANUAL
Where drugs or chemicals are to be used to treat parasites, a disease, or an infection, it is important that
the label describing how it should be used is properly read, and the instructions followed. The label will have
instructions on when and how to use the product and the recommended dose rate. There will possibly be
warnings on when not to use it, such as on lactating cows, and the recommended methods of storage and
disposal, and an expiry date. As with external parasites, records of all animal treatments must be kept by the
producer which includes the batch number and date of application of the treatment.
Figure 4.30. Liver Fluke. Source: Hybu Cig Cymru.
Liver Fluke Liver luke can have a major efect on the performance
of cattle. Current estimates suggest that luke can reduce the market value per inished animal by 10 to
15. Taking action to control the damage caused by liver luke will help reduce liver condemnations in abattoirs
and improve the performance of the animal. Liver luke Fasciola hepatica is a lat leaf-like parasite
found in the tissue and bile ducts of the liver Fig. 4.30. Adult lukes only measure 2-3cm but cause severe
damage to the cattle they infect Fig. 4.31. To reduce
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Cold Winter Climates
Figure 4.31. Damage caused to the liver from Fluke. Source: The Merck Veterinary Manual.
the spread of live luke cattle should only have access to water in troughs and be kept away from any surface
water that may have the host snail present.
Roundworms Parasitic roundworms, or nematodes, are found year-
round in cattle in most areas of the world. These parasites live in many sites including:
• Lungs • Body cavity
• Tear or lacrimal ducts • Beneath the skin
• Gastro-intestinal tract. Each area is occupied by roundworms speciic to those
sites. Cattle producers should be aware of the more important worms that can live in their cattle.
Cattle can host over 14 diferent species of gastro- intestinal roundworms. Diferent species live in diferent
locations in the intestine. As there are usually just a few of these roundworms present, the harm they cause is
not always apparent and can be diicult to assess. An efective way to detect the prevalence of roundworms
and to determine if an anthelmintic treatment is required to improve health and production is through a faecal
egg test. Using fresh faeces, an estimate of the number of nematode eggs can be derived, and if the number of
eggs is high then treatments can be implemented.
4.5.3. Diseases Affecting Reproductive Performance
