Intestinal worms in livestock – Testing and controlling worms

Livestock and pets are prone to many different intestinal parasites. Some of these can cause ill thrift, scouring, anaemia or even death.

Nematodes (such as the deadly barbers pole worm)

Common nematodes found in livestock include the roundworms, black scour and barbers pole worm. These hook into the wall of the stomach or small intestine with specialised mouth parts, make a small cut and then proceed to feed on the blood of the host animal. Each cut creates a small scar, which cannot absorb nutrients. The more scars an animal has, the more it needs to eat to get the same amount of nutrients from the feed. If nematode infestations continue untreated, the animal becomes anaemic and will eventually die.

Barbers pole worm burdens can build up quickly to deadly levels in sheep and goats. The worms become active after the first spring rains, when the weather starts to warm up. Within 21 days after ingestion, the parasite begins laying 5,000-10,000 eggs per day.

Barbers pole worm accounts for more livestock deaths in sheep and goats than any other parasite in Australia.

Tape worms

Tape worms compete with livestock for nutrients. Even more seriously, an infestation by the hydatids tape worm can transfer to humans and cause cysts in  the liver, brain or lungs. This can be fatal. Humans are the end host for the hydatid tape worm, with dogs the intermediate host and sheep the primary host.

Liver fluke
Liver fluke, once ingested, infect the liver of sheep and cattle by penetrating the intestinal wall into the abdominal cavity. From there, they penetrate the liver capsule and spend a few weeks migrating through the liver before entering the bile ducts. After spending several weeks developing in the bile ducts, they mature into egg laying adults. The damage caused by the immature migrating fluke larvae can cause jaundice, liver failure, haemorrhage or death in severely infected animals. As a zoonotic disease, liver fluke can be passed from animals to humans, which has serious consequences.

Coccidia
Coccidia are small, microscopic protozoa that cause coccidiosis infection. Young livestock (under 3 months of age) with the infection can suffer from scouring, ill-thrift and even death. Alpacas, sheep and goats usually develop immunity with age, unless they are in poor condition.

Worm treatment and testing
Simple worm treatment strategies that small landholders can implement to control intestinal worms and also prevent zoonotic diseases include:

1. Regular worm testing, including egg counts and worm type. Worm test should be conducted every six months or at least once a year. However, they should be conducted more often if livestock are showing symptoms that could be due to internal parasites. If you have a positive result from a worm test, drench without delay using a drench suitable for that species, at a dose rate appropriate for the heaviest animal in each class of livestock i.e. kids, lambs, crias, adult females or males.

2. Quarantine drenching. Drench all incoming livestock with a broad spectrum oral drench suitable for that species, as recommended by your animal health adviser. The latter is especially important for alpacas as there are no drenches registered for them. Keep new livestock confined in a small area away from others for a minimum of 1 week allowing them to empty out any worms. If this isn’t done paddocks can quickly become infested with worm eggs, or worse still, you can bring drench resistant worms onto your farm.

3. Regular worming of dogs. Giving your dogs a regular worm treatment will help ensure they do not become hosts for any zoonotic diseases.

4. Using good hygiene when working with livestock, by not eating or smoking while handling them and washing your hands prior to eating.

Where to from here?
For further information on intestinal worms consult your veterinarian or NSW DPI factsheet resources.

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