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Goat production guide – Part 4(ii): Internal and external parasites

Goats can have internal parasites (inside the intestines and other organs) and external parasites that stay on the outside of the animal.

Internal parasites

Worms and flukes

Generally, these parasites cause harm either by absorbing the goat’s food or by feeding on the blood or tissue of the goat. There are different types of worms, some which are easier to see (such as tapeworms) and some which are more difficult to see (such as roundworms). Roundworms (which include wireworms) cause serious losses if not properly controlled. Tapeworms cause a ‘potbelly’ in young animals.

Another type of internal parasite is the liver fluke which is found in the goat’s liver. The goat becomes contaminated when he feeds on plants growing near water bodies (wetlands, marshes and standing water). Liver flukes cause symptoms similar to those of roundworms.

Even if they do not make the goat sick, internal parasites reduce its productivity. If the goat has heavy infestations, it can lose condition, become anaemic (from loss of blood), become listless, develop a ‘bottle-jaw’, suffer from diarrhoea, and even die. Some tapeworms form cysts in goats’ brains, which lead to mortalities. It is a tapeworm that they pick up from dogs. The cysts cause ‘malkop or draaisiekte’, as discussed in the previous article.

Use of anthelmintics (dewormers)

Goats can be dosed with a variety of dewormers – some only kill one type of worm, while others kill a range. You should try and dose for the particular worms that are affecting your goats. Resistance will build up over time, so regularly change your dewormer ensuring to use different active ingredients. Unless you have a particular type of worm that you are trying to treat, you should swap dewormers regularly (check that they have different active ingredients) to make sure that over time you control the different types. You also need to make sure that the product you are using is safe for goats.

It is recommended that you use a FAMACHA chart and the 5-point check system described below to control parasites in your goats. You can use a standard dosing programme based on periods of heavy infestations and dose the whole flock at certain times of year.

If it is possible, call in a technician to send a dung sample to a laboratory to determine what worms are infecting your goats. You should collect a sample directly from some goats and not from the ground. Keep samples in plastic packets in the fridge until you take them to the lab.

If you plan to slaughter the goat to eat, you should also check the withdrawal period of the product (this is the recommended time period from the time of dosing to when it is safe to eat the goat or drink its milk). Many medicines also have a withdrawal period.

Observation points to determine internal parasites

Certain signs help you to determine which goats or sheep could be affected by one or more major internal parasites. Five places on the body need to be checked. Those places are the nose, eyes, jaw, tail, and the back.

Nose: Discharges from the nose may indicate nasal bot fly (Oestrus ovis).

Jaw: A soft, subcutaneous swelling below the jaw is known as the bottle jaw. This is another symptom of worm

species that cause anaemia.

Eyes: Anaemia (as determined by the use of FAMACHA©) may be due to wireworm (Haemonchus contortus) and other worm species such as hookworm that cause anaemic conditions.

Back: Body condition scoring is the assessment of overall condition of the animal. If only a few in the flock show poor condition, this may show worms that suppress the animals’ appetite, such as bankrupt worm, brown stomach worm and conical fluke.

Tail: Parasites such as conical fluke and roundworms cause mild or severe diarrhoea. Parasites are known to be a major cause of diarrhoea therefore the farmer needs to treat those with visible diarrhoea.

Other observations, such as a pot belly, when combined with poor condition or growth rate, is usually an indication of tapeworm infestation.

There are other ways to control the worm burden in your goats:

•Goats pick up worms from the grass when they are grazing (the eggs come out with the faeces and then infect the camp). You can practice rotational grazing to prevent a build-up of worms in your camps.

•Repair leaks in troughs as worms breed in the muddy ground around the trough.

Checking for signs of anaemia

The FAMACHA method is suitable for controlling wire worms because it is based on assessing the level of anaemia in the goats (from looking at the inner membranes of their eyes) and then dosing only those that are anaemic. If the membranes are pale pink instead of bright pink, they are anaemic. The paleness occurs because the worms have been feeding heavily on the goat’s blood. However, the FAMACHA method will not pick up tapeworm.

Another key measure to control worms, is to identify goats that are particularly susceptible to worms and cull them, because these goats actually keep infecting other goats in the flock. If you check your goats’ eyes regularly and find that a certain animal often has pale membranes, then you should not just continue to treat it for worms – you should actually sell or slaughter it.

External parasites

External parasites affecting goats are mainly ticks and mange mites. Other examples would include mosquitos and flies (especially blowflies). Some external parasites cause skin irritation and tissue damage, while others also transmit diseases to the goat.

Ticks

Besides the physical damage caused by ticks, they also transmit a number of diseases. In goats, the most serious tick-borne disease is heartwater. Tick-borne diseases are specific to a certain type of tick. For example, heartwater is only transmitted by bont ticks. Ticks can be controlled by insecticides that can be applied in different ways. Spraying is the most common way, and less common is either dipping the goat (in a plunge dip or with a bucket and sponge), applying a pour-on product onto the animal’s back, or by injecting it with a registered product.

Remember that dips are poisonous so you should make sure that you use gloves and protective clothing to prevent skin contact as you can actually absorb the dip directly through your skin.

Mange

Mange is inflammation of the skin (causing itchiness) and the loss of hair, and is caused by small organisms called mites – they are too small to actually see. The same mites cause sheep scab in sheep. Dips and injectable products are available to control mange.

Fleas

These are small wingless insects that move around different hosts by means of jumping. They have well-developed legs that are used for jumping considerable distances. They range between 1 mm and 8 mm in length. Fleas are normally found on dogs and cats. In that way they are passed on to domestic livestock like goats.

Fleas cause rubbing of affected areas, scratching, and hair loss. They can be controlled by dipping the goats and treating the affected areas with sprays or powders such as Karbadust.

Lice

There are two recognized types, the biting (red) lice and the sucking (blue) lice. The biting lice feed on dead skin, while the sucking lice actually suck blood from the host. Both types cause the animal to itch, and in most cases causing the animals to rub against objects. Lice are normally found on the insides of the legs and around the head and neck, and may result in scabby or bleeding areas, loss of hair or a dull coat.

Severe cases can cause anaemia. The goats should be sprayed or dipped, and the kraal should be treated with an insecticide. (They can also be dusted with Karbadust).

Infected animals should be separated to prevent the lice from spreading to other goats.

Nasal worm

Nasal worms are not proper worms, but actually the larvae or bots of a fly. The fly lays its eggs around the nose of goats, and the eggs hatch into larvae which travel up the nose into the sinuses in the goats head. Here they cause irritation, inflammation and mucus that runs out of the nose, the goat coughs and sneezes and shakes its head until it eventually gets rid of the bots that then turn into flies again.

Fortunately, these nasal worms are easy to get rid of. The most effective method is to treat animals with a remedy that contains ivermectin or closantel. Some deworming products, such as Tramisol, can also be used.

Sometimes the bots cause secondary infection of the sinuses or even infections that eventually spread into the lungs. These infections must be treated with long-acting oxytetracycline products.

The information in this article is credited to Mdukatshani, Heifer International South Africa and the KwaZulu-Natal Department of Agriculture and Rural Development who published the Goat Production Handbook in 2015.

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