I don’t know about you but every time I visit my vet I’m immediately confronted with posters highlighting the importance of worming your pet dog, cat and even your horse. Treatment for infestation of roundworms in puppies and kittens and for tapeworms later on in life is usually accepted as a sensible course of action to keep your pet healthy and our approach to our poultry shouldn’t be any different, for there are worms that thrive in our birds and though the problem is more acute in the warmer summer weather than in cold winter time with global warming and the trend for warmer wetter winters, worms are becoming more of an all year round problem.
So I thought I’d go back through my old college notes – thank you Broomfield College – and put together some advice on worming. I worm my small flock twice a year in Spring, usually in March and again in October. This is an important part of my animal husbandry to ensure a healthy and productive flock. Worm infestations can damage your birds gut leading to a variety of undesirable conditions including:
• Loss of shell colour and strength, yolk colour and egg size.
• Loss of body weight.
• Dull, listless birds with comb colour fading.
• Poor feed conversion.
• High risk of egg peritonitis.
• Waterfowl going off legs
• In severe cases even death.
Generally, the birds most at risk of worm infestation are those on free range or flocks reared in deep litter systems. Worm eggs and their vectors [a vector is a carrier of a disease causing agent], such as beetles and flies thrive well on litter and soil. Earthworms, slugs and snails can also be vectors meaning the problem is in the soil as well. Depending on the species of worm, eggs can survive for months and in some cases for over a year without a host. Then, if birds are not wormed, the problem of infestation increases as infection and re-infection occurs.
These are the main worms that could affect small flocks:
• Roundworms [Ascaridia galli]
• Hairworms [Capillaria]
• Caecal worms [Heterakis gallinarum]
The most common worms that affect poultry are in fact nematodes or roundworms and the most common nematodes are called ascarids, also known as roundworms. Roundworms can affect chickens, turkeys, doves, ducks and geese. They are usually found in the intestine but can appear in the oesophagus, crop, gizzard, oviduct, or body cavity. The most obvious symptom is unexplainable weight loss and loss of condition often accompanied with a general listlessness and diarrhoa but a severe infestation of roundworms can cause an intestinal obstruction which can result in death.
Gapeworm [Syngamus trachea]
This is a common nematode parasite of the respiratory tract. Game birds, especially pheasants, as well as turkeys and chickens can be affected. Birds with gapeworm infestation will quite literally gape – opening their beaks in a gasping manner – showing signs of respiratory distress and shortage of breath due to damage to the lungs and the trachea, caused by the worms. As well as gasping for breath, depression, loss of appetite and condition is seen as well as head shaking in an attempt to remove the worms. A gurgling sound made during breathing can be heard in many cases, which is often mistakenly diagnosed as a respiratory infection, rather than worm infestation. Gapeworm can be carried by earthworms, slugs and snails and once a susceptible bird ingests an infested host/transfer vector, the larvae penetrate the wall of the intestine and eventually end up in the lungs. From the lungs they migrate into the bronchi. A moult of the larvae results in the adult gapeworm, which then move to the trachea where the male and female worms intertwine and attach themselves to each other permanently. The time span from the bird ingesting the earthworm to adult gapeworms being found in the trachea is approximately 7 days.
Gapeworm egg production begins a fortnight after infestation of the larvae. The eggs are then coughed up into the mouth of the bird, swallowed and passed out into the faeces. In the droppings the eggs incubate for 8 to 14 days before coming infective larvae and thus the life cycle begins again.
This is one of the most difficult worms to diagnose, partly because it is barely visible with the naked eye. They are only around 10mm long and 0.05mm wide. They can however, cause a significant amount of damage even in only moderate infestations. Hairworms are so small that sometimes they can go completely unnoticed during a post-mortem and are only found through a microscopic examination. The typical symptoms are diarrhoea wasting and a loss of condition.
These form another group and are found mostly in the lower end of the gut – the caecae. Normally they cause less harm than other worms; however, they can carry another parasite [Histomonas] into the bird. Histomonas is the cause of Blackhead – infection in the liver and caecum – in turkeys and pheasants. Partridge, peafowl and guinea fowl are also vulnerable. The first signs of Blackhead are usually a dull, listless bird, often with wings fanned to the ground, ruffled feathers, with bright sulphur yellow loose droppings. At present there is no cure for Blackhead as the only drug to effectively treat an infected bird – Dimetridazole – has been suspended from the market. Good hygiene and a strategic worming programme to attack the host worms is the best course for controlling the histomonas parasite.
Poultry can also suffer from tapeworms that live in the intestinal tract and compete with the host for the nutrients in the feed. The tapeworm latches its hooks in the fold of the intestinal mucosa, which can cause severe damage, resulting in body fluids being lost. Sometimes specific species of poultry can become infected with a particular type of worm. This is the case for geese and ducks that are vulnerable to stomach worm [Amidostomum anseris].
So with different species of worms affecting poultry treatment is important because:
• Worms are common and almost inevitable in laying flocks unless birds are effectively wormed.
• Birds become infected by picking up worm eggs from grass, soil or faeces.
• Once worms are present they can build up quickly.
• Worming infrequently may not prevent re-infection, for although adult worms may be killed with the initial treatment there will no doubt be eggs and larvae waiting to emerge.
To identify if your birds have a problem wirh worms the first thing to do is become a ‘poo inspector’. Worms can be most easily identified by examination of droppings for the presence of visible roundworms. Should you want a more detailed assessment, then asking your vet to carry out a check on dropping samples is a great help with establishing if any birds are suffering from hairworms.
If it is discovered that worms exist what is the action to take?
• Strategic worming according to level of infestation and the birds’ environment.
• Rotate birds onto fresh pasture [if room permits] to prevent land becoming ‘fowl sick’. If birds are housed during the winter or can be moved to a spare area, then liming the resting area is recommended. This will help to reduce the worms and clean the land.
• Put poultry on good draining land or try to improve drainage.
• Avoid putting birds on poached, muddy areas that encourage worms.
• Use pea gravel in the area close to popholes to help clean feet and allow droppings passed there to dry, be broken up and be exposed to ultra violet sunlight which will kill worms.
• Changing the litter in housing once a week will break the 8 – 14 day cycle needed for eggs to incubate into infective larvae.
• Never feed on the floor or on the litter.
• Be aware that worm carriers are the earthworm, cockroach, beetle, grasshopper, earwig, flies and snails.
• Develop good hygiene practice and keep housing and feeding equipment clean, using a disinfectant such as Virkon S or F10.
How to treat
There are many wormers available however some products on the market which are effective in the treatment of internal and external parasites are not currently licensed for use in poultry. These may still be used if prescribed by a vet.
The anthelmintic [wormer] that is licensed for poultry is flubendazole, traded as Flubenvet from Janssen Animal Health. This is widely available at most Feed merchants, it is mixed dry, into the feed at 10g to 8kg feed for seven days [Quick Tip: use a small glug of vegetable oil if you feed pellets, this helps the flubenvet stick to the pellets and not collect at the bottom of the feeder.] How often you need to worm will very much depend on the number of birds you have, the species you keep and their environment. As a general guide, chickens should be wormed two to three times a year but with a strategic plan for your situation this could change according to the level of worm infestation, with wider periods between worming as the threat of
re-infection decreases. Geese and ducks require more regular worming against stomach worms. Should turkeys be kept near or with other poultry then it is advisable to worm all the birds every six weeks, so that the threat of Blackhead is reduced.
If you use Flubenvet birds must not be slaughtered for human consumption during treatment. Chickens, turkeys, geese, pheasants and partridges may be slaughtered for human consumption only from seven days from the end of treatment. The eggs from turkeys, geese, pheasants and partridges may only be presented for human consumption after seven days from the end of treatment. Chicken eggs may be presented for human consumption during and after treatment when dosed at the suggested rate.
Once a worming programme is applied a real risk to your poultry’s health will be reduced. Worms are a severe threat to a bird’s overall condition, making it more susceptible to other ailments and disease. Whether kept for egg or meat production, healthy worm free birds will be easier to maintain and most importantly, more productive.