CONTROL IN POULTRY
By Dr Colin Walker BSc, BVSc, MRCVS, MACVSc
Parasites of concern in poultry are roundworm, hairworm and tapeworm,
Coccidia and lice and mites. Worms
are extremely common, particularly in free-range poultry. Being a
primary parasite, they drain the birds of nutrition, causing ill-thrift,
a general failure to thrive, a vulnerability to other diseases, and,
in severe infections, death. Both roundworm and hairworm have what
is called a direct life cycle in that the eggs are passed in the
droppings and after a period of time in the environment, become infective.
New birds become infected by inadvertently eating these eggs while
feeding, drinking or scratching around their yard. Once an egg is
swallowed, it hatches and eventually matures into a new worm in the
In roundworms, the life cycle is particularly short, being only
21 days. This means that if a chicken is wormed and swallows an
infective egg the very next day, in only 3 weeks that chicken will
have mature roundworms in its bowel again. To completely eradicate
roundworms from a flock involves worming the birds every 3 weeks
and each time following up with a particularly thorough clean of
the yard. Ongoing hygiene is particularly important because any
dropping passed prior to worming will contain worm eggs that have
the potential to reinfect the chicken. Often in a free-range situation,
no matter how thoroughly one cleans, it is not possible to completely
remove every piece of dropping and so some reinfection does occur.
In this situation, regular worming is done, not so much to eradicate
any parasites but rather to keep them at a low level where they
are not causing clinical disease. Often here, in a yard that is
basically clean, worming every 3 months will provide adequate control.
There are many medications on the market to worm birds, but the
one I recommend is Moxidectin. It provides good clearance of roundworms
and hairworms, is very safe and easy to administer, and has the
handy side effect of killing any external parasites that feed off
body fluids. This includes all mites. The dose of Moxidectin 2
mg/ml for the flock is 5 ml to 1 litre of water for 24 hours. This
dose is based on normal water consumption. If for one reason or
another the birds’ water intake on that day is low, the drug
is safe enough to provide for a second or a third day to ensure
that all birds receive an adequate amount. If some birds receive
a double or triple dose, this will do them no harm. It is important
that the water containing the Moxidectin is mixed freshly each
day, however, and that, of course, no other water sources are available.
Moxidectin can also be given to individual birds at the dose of ½ ml
per kg as a single dose orally.
Tapeworms have a more involved life cycle. The adults, which live
in the bowel, pass packets of eggs in the droppings that need to
be eaten by an insect to become infective. Chickens can only become
infected by eating insects carrying the tapeworm larvae. It is
often possible to tell if a chicken is infected by tapeworms simply
by looking at the droppings. Tapeworm egg packets are visible to
the naked eye and appear as white pellets stuck in the droppings.
Most are about the size of a grain of rice but bigger and smaller
types occur and sometimes rows of egg packets can be passed together,
which appear as white ribbons in the dropping. The only way to
reliably tell if a chicken has roundworms or hairwoms is through
a microscopic examination of the dropping. The usual drug used
to treat tapeworms is Praziquantel. This is available in a variety
of tablets and syrups. I usually use the brand Prazivet, which
is added to the water at the rate of 5 ml to 1 litre for 24 hours.
Like Moxidectin, an individual bird can be treated with Prazivet
by giving ½ ml of the neat solution per kilogram of body
weight as a single dose.
Coccidia are protozoan organisms that live in the lining of the
bowel. Infected birds are usually lethargic, underweight and have
diarrhoea that can be blood tinged. The Coccidia eggs are released
in the droppings and fresh chickens become infected by inadvertent
ingestion of grain or water contaminated with these droppings.
In a free-range situation, most chickens have a low-level ongoing
exposure to Coccidia. Rather than make them sick, this stimulates
the development of a strong natural immunity that keeps them healthy.
Chickens become unwell with Coccidia in one of several situations,
for example, where they are housed in dirty damp conditions that
provide a high level of exposure to the organism, or where they
become run down generally, in which case the Coccidia will multiply
and cause disease. Alternatively, if chickens which have a low
natural immunity to Coccidia suddenly come in contact with even
moderate levels, then disease can occur. Coccidia is diagnosed
through microscopic examination of a dropping sample. Often where
Coccidia is diagnosed, it is important to review the general management
and housing as flaws will often be found here. The drug I recommend
to treat Coccidia is Baycox. This is used at the rate of 3 ml to
1 litre of water for 48 hours. Where a flock is having an ongoing
problem, this treatment is usually repeated every 4 - 6 weeks until
the birds develop a stronger natural immunity to this parasite,
while all the time ensuring that the birds are generally well cared
for and that their pen is kept clean and dry.
The two main external parasites of chickens are lice and mites.
Red mite, in particular, seems ubiquitous in chickens and is a
common cause of failure to thrive. Severe infections will kill,
particularly young chickens due to anaemia and it is vital that
management protocols are in place. Lice live off feather debris
and cannot survive off the chicken. Mites, on the other hand, feed
off body fluids and survive well in the environment. Only a small
number of the mites infecting a chicken are found on the bird at
any one time. Many live in the nooks and crannies around the pen.
To treat lice is a simple matter. As they cannot survive off the
bird, it is simply a matter of dipping all of the birds. Mites
can be removed also by dipping, however, as mentioned earlier,
Moxidectin can be used in the birds’ drinking water to kill
mites on the bird at that time. With mite infestation, however,
it is vital to also treat the pen at the same time otherwise reinfection
quickly occurs. When treating the pen, it is scraped and cleaned
out as normal but then an insecticide is misted onto the scraped
surfaces and into the nooks and crannies. This is usually done
on the morning of a warm day and when the pen is dry after a few
hours, the birds are readmitted. The recommended insecticidal spray
is Permethrin. This is available in a number of preparations but
I find it easiest to use as a water-soluble liquid where it is
diluted 10 - 20 ml/l. Permethrin is also the dip of choice in chickens.
To prepare the dip, add the Permethrin at the same rate of 10 -
20 ml per litre of water and add also a wetting agent such as baby
shampoo or a few shavings off a bar of soap. Ensure that the water
is warm and dip the birds in the morning of a warm day so that
they have a chance to dry before nightfall.
PROGRAM FOR PARASITE CONTROL IN FREE-RANGE CHICKENS
Moxidectin 2 mg/ml, 5 ml per litre of water for 24 hours every
Monitor the droppings for tapeworm segments and if observed give
Prazivet 5 ml per litre of water for 24 hours.
If Coccidia is a problem, give Baycox 3 ml to 1 litre of water
for 48 hours every 4 weeks as required
Dip all birds in Permethrin and any new introduced bird. Ensure
that the pen is sprayed simultaneously.