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Online learning: Tasmania—Goat worms

This covers the important worms and aspects about them you should know most about.

Structured reading

For those who like to see all the information and simply read through it in order. Each heading is a link to a page of information—the dot point provides a summary of the page.

Tip: Keep this page open and open the links in new tabs.

Roundworm life cycle
A diagram and description of the stages within the worm life cycle and how these affect control of and contamination by roundworms.

Worms on pasture
A table showing factors contributing to paddock contamination with worms

Signs of worms
The clinical signs that can be present with infection by various worms.

Barber's pole worm
A description about barber’s pole worm, its location, signs, diagnosis and treatment.

Black scour worm
A description about black scour worm, its location, signs, diagnosis and treatment.

Brown stomach worm
A description about brown stomach worm, its location, signs, diagnosis and treatment.

Intestinal tapeworm
A description about the intestinal tapeworm, its location, signs, diagnosis and emphasis that treatment for this very obvious and common worm is NOT warranted.

Liver fluke
A description about Liver Fluke, its lifecycle, disease signs, treatment and prevention.

Tasmania: Liver fluke control
Liver fluke control for this region

Other worm pages
These pages are optional reading, as the worms are less important and are generally controlled when treatment of the more important worms is carried out.

Question and answer

For those who prefer a problem based approach to learning, answer the following questions.
Each of the questions below links further down the page to the answers.

Questions:

  1. Typically what proportion of the total cost of worms is attributed to production loss, rather than control costs?
  2. What is the length of the prepatent period of typical roundworms?
  3. Are worm eggs able to wait for months and then hatch when conditions are favourable?
  4. Name to two common signs associated with a severe infection of either barber’s pole worm or liver fluke.
  5. What type of environment do barber’s pole worm prefer?
  6. There are two common species of black scour worm, which one is the most pathogenic and where does it more often occur?
  7. On properties where liver fluke occurs, when is the most important time of the year to treat for liver fluke?

Answers:

You can also click on each question below to go to WormBoss pages with related information.

1. Typically what proportion of the total cost of worms is attributed to production loss, rather than control costs?

Roundworms cost the goat industry $2.5 million per year (Lane et al. 2015) and about 70% of the annual cost is associated with lost production and the remaining 30% with the costs of control. Most of these costs occur with farmed goats in the medium and high rainfall zones, rather than in the rangelands but are still the most important health cost across the Industry.

2. What is the length of the prepatent period of typical roundworms?

This is the time taken for infective larvae, eaten by a goat grazing pasture, to develop to adult worms in the gut, mate and start laying eggs, which appear in dung. The time depends on the worm species with barber’s pole worm completing this period in a minimum time of 18 days under ideal conditions. Most scour worms take about 21 days.

3. Are worm eggs able to wait for months and then hatch when conditions are favourable?

As worms require both warmth and moisture for eggs to develop to larvae (above 10–18°C depending on worm species, but ideally below 35°C, and with usually more than 15 mm rain over 4–7 days of rainy or overcast weather when the evaporation rate is low), there can be extended periods of the year in some locations when worms cannot successfully complete their life cycle. These include regions with particularly cold winters or hot summers or where there are lengthy dry periods.

Barber's pole worm eggs will die if these conditions are not met within about 10 days of them being deposited on the pasture. Scour worm eggs are able to survive a few more weeks awaiting suitable conditions for hatching

4. Name two common signs associated with a severe infection of either barber’s pole worm or liver fluke.

Severe acute or ongoing (chronic) blood loss from either barber’s pole worm or liver fluke leads to obvious signs of anaemia. These are pale gums and conjunctiva (inside the eyelids); lack of stamina causing lagging or collapse when mustered; and ultimately death from lack of red blood cells needed to carry oxygen around the body.

Swelling under the jaw (bottle jaw) results from both severe barber’s pole worm and liver fluke infections. The loss of blood results in anaemia and less protein in the blood. This imbalance in the normal body fluids results in fluid accumulating under the jaw in some, but not all, affected animals. It does not always occur during an outbreak of barber’s pole worm disease, and can also be caused by other factors (e.g. Johne’s disease in goats).

5. What type of environment do barber’s pole worm prefer?

Barber’s pole worm is most commonly found in Queensland and the northern half of NSW where summer rainfall is common or dominant. This worm is less of a problem in the winter rainfall areas of Australia, but localised pockets exist in all states and infections are worse in summers that are wetter than usual.

6. There are two common species of black scour worm, which one is the more pathogenic and where does it more often occur?

Black scour worms occur in all goat production districts of Australia. Trichostrongylus colubriformis and Trichostrongylus vitrinus are the main species causing disease in Australia. Generally, T. colubriformis occurs in the warmer summer rainfall areas and T. vitrinus occurs more frequently in winter rainfall areas.

T. vitrinus is considerably more pathogenic than T. colubriformis, meaning that it needs to be treated at lower egg counts. Regular worm egg counts are essential for successful management.

7. On properties where liver fluke occurs, when is the most important time of the year to treat for liver fluke?

The most important treatment is carried out in April–May and should be based on the flukicide, triclabendazole, which is effective against all stages of the fluke found in the goats. If treatments are also required in August–September and/or February, one or both of these treatments should be a flukicide other than triclabendazole (if this was used in April). This treatment rotation will reduce the rate of development of fluke resistant to triclabendazole.


Links to the learning topics for Tasmania

  1. Introduction
  2. Grazing management
  3. Breeding for worm resistance
  4. Worm testing
  5. Drenching
  6. Drench resistance management
  7. Goat worms (you are currently on this page)