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evak animal health


Treatment Programs

Coxxitec (Evak owned subclinical coccidiosis control  program)

Coccidiosis is a common parasitic disease of broiler chickens caused by single-celled protozoan parasites of the genus Eimeria which are commonly referred to as coccidia, explained Dr Hector Cervantes of Phibro Animal Health Corp during a presentation at the 2008 North Carolina Broiler Supervisors Short Course.

He said that there are two types of coccidiosis:

  • clinical coccidiosis in which the affected birds show typical symptoms of the disease, such as bloody droppings and increased mortality, and
  • subclinical coccidiosis because the affected birds do not show visible symptoms of the disease but when a random sample of birds is examined, the presence of the gross lesions and the coccidia are found.

Because most broiler feeds contain anticoccidial drugs, cases of clinical coccidiosis are rare. However, the most frequently diagnosed subclinical disease of broiler chickens in the USA1,2. It is difficult to diagnose and treat because the birds appear normal although their performance is usually substandard.

As long as broiler chickens are continued to be raised in confinement under the current production systems, says Dr Cervantes, the prevalence of subclinical coccidiosis is unlikely to change, yet no new anticoccidial drugs are being developed. Prevention and control methods must be used to minimize the negative impact of subclinical coccidiosis on broiler flock performance.

Important Coccidia in Broiler Chickens

After describing the lifecycle of Eimeria, Dr Cervantes turned his attention to the types of coccidia. Although there are seven widely recognized species of coccidia, only three of them cause most of the problems related to coccidiosis in the USA: Eimeria acervulina, E. maxima, and E. tenella.

Each species of coccidia has its own unique area of the intestinal tract. For example, E. acervulina lesions are found in the upper small intestine, while those of E. maxima will be found in the middle small intestine and E. tenella lesions in the caeca. It is important to identify the type of coccidia affecting the flock as they require different treatments.

Coccidiosis Prevention

Coccidial oocysts are extremely resistant to environmental conditions and disinfectant agents so eradication of coccidiosis from chicken houses by litter removal, cleaning and disinfection is not feasible.

Since the early 1950s, writes Dr Cervantes, there have been two main tools to prevent and control coccidiosis in broiler flocks. Anticoccidial agents added to the feed have been used since the mid-1950s and have been instrumental in allowing the expansion of the broiler industry to what it is today.

For many years coccidiosis prevention and control relied on the use of synthetic anticoccidials, commonly referred to as chemicals. In many cases, resistance to these drugs quickly occurred – within 1 to 3 years – and they became ineffective. Of this group, only nicarbazin remains effective today.

A major breakthrough in the prevention of coccidiosis through feed medication occurred in 1972, with the launch of the first polyether ionophore anticoccidial, monensin. This type of anticoccidial agents have been commonly referred to as ionophores, a term derived from their general chemical structure. They are the most widely used drugs for coccidiosis prevention in broilers. Each has a different mode of action and so no significant resistance has developed. Monensin, for example, is still used successfully more than 35 years after its introduction.

The second method for the prevention and control of coccidiosis in broiler chickens that has been available since 1952 in the USA, is through the use of live non-attenuated coccidiosis vaccines. For many years, the use of live coccidiosis vaccines was restricted to broiler breeder replacements.

The introduction of better and more practical vaccination techniques, e.g. the administration by coarse-spray or gel-spray cabinet at the hatchery, has resulted in more uniform administration and better protective immunity. Use of coccidiosis vaccines has increased in broiler chickens but this remains a relatively minor use compared to anticoccidials drugs in the feed.

New methods of administration of live coccidiosis vaccines, like the in-ovo injection method into embryonated chicken eggs at 18 days of incubation, allowing precise individual dosing and the early development of immunity.

What are Shuttle and Rotation Programs?

They are management programs designed to prevent the development of resistance to anticoccidials thereby resulting in better gut health and feed utilization by birds.

Shuttle: refers to the use of two or more products during the grow-out of a flock. The reason for use of a shuttle is that results are better than if either drug was used by itself. The principle of shuttles is that the best drug is used for each phase of the grow-out i.e. most suitable drug is used for starter, while another drug is used for grower and finisher. Drug withdrawal period is the most important consideration for drugs that will be used in finisher feeds.

Factors To Be Considered in Designing Programs for the Control of Coccidiosis

Past Experience: This pertains to what drug(s) have been used in the past for an operation and the results obtained. An example would be if E.maxima was determined to be a problem (poor weight for age and feed efficiency but not mortality) then a drug(s) particularly effective against this species should be used for birds 3 weeks of age and older.

Species of Cocci by Phase of Grow-out Although there are occasional cases where massive infections occur with multiple species of cocci, generally we see an orderly sequence of infection in Ontario:

  • 18 – 28 days – upper gut E.acervulina
  • 25 – 35 days – mid-gut E.maxima
  • 32 – 42 days – caecal – E.tenella (although can occur much earlier)

Thus in planning shuttle programs we can use drugs that are particularly effective against the species expected to cycle at that stage of a grow-out

Winter or Summer Use

Besides controlling coccidiosis, drugs may influence the bird by such factors as water consumption, feed intake, heat tolerance etc. If one has difficulty in maintaining litter quality because of water quality (high sulphates) or poor insulation, then a drug that restricts water consumption would be a benefit for use in starting birds in winter months. In contrast, a drug that does not restrict water intake or decrease heat tolerance is essential for the summer months.


A coccidiosis ‘Break’ is often an indication of an immunosuppression problem (Mareks, Bursal Disease and/or Chick Anemia Agent). This is because ionophores depend on the bird being able to develop immunity does not develop, the bird is ‘overwhelmed’ with cocci and a ‘break’ occurs. Non-ionophores are warranted when one is dealing with an immunosuppression problem


Withdrawal Period

Food safety is the first priority, so drug withdrawal time must be respected. Those drugs that have a zero-day withdrawal give more flexibility in finisher feeds. However, if drugs restrict feed and water, they should be removed prior to marketing so birds have a chance for ‘compensatory gain’.

Why Use Shuttle and Rotation Programs?

Resistance – this term is used to indicate a loss of protection by a product which may be recognized more commonly by poor weight for age and feed efficiency, rather than clinical disease.

It is well documented that resistance will develop to any anticoccidial that is used on a continuous basis. The ideal anticoccidial program should compensate for resistance that may be present to existing products and preserve the efficacy of new products. Shuttle programs do this by permitting use of the correct drug for each need. Rotation programs achieve this by eliminating resistance to a particular family of drugs by use of drugs with a totally different activity-mode of action.

Rules for Shuttle and Rotation Programs?

The basic rule for shuttles is to use the best drug for the purpose at hand. With the exception of Maxiban or Nicarb which are used in the started, non-ionophore usually follow ionophores. This is to prevent late cycling of coccidiosis in the grow-out. The key aspect of rotations is to alternate drug chemistries i.e. non-ionophores follow ionophores. Use of two ionophores back-to-back in a rotation is unlikely to give desired results.

Rotations vary from four to six month intervals for chickens (usually at least two crops) – and eight to twelve months for turkeys. Summer and winter programs are very appropriate for the Canadian market. Non-ionophores should not be used for longer than 6 months.

Diagnosis of Coccidiosis

Despite most broiler flocks are raised with anticoccidial drugs added to their feed, drug resistance – especially to chemical anticoccidials or feed mixing errors – may lead to clinical coccidiosis.

Birds with clinical cases of coccidiosis frequently display a typical ‘sick bird’ attitude with depression, prostration, huddling under the heat source as if chilled, soiled vents and watery or bloody droppings. One of the first signs of clinical and even subclinical coccidiosis may be paleness.

In birds that have recently died, postmortem examination should start with examination of the intestinal tract and the caeca for the presence of gross lesions. Gross lesions caused by E. acervulina are usually the most prevalent and are usually confined to the upper small intestine (duodenum), although some times they may extend to the mid-gut (jejunum). The lesions have a unique appearance, consisting of white patches or transverse white lines inside the gut that may already be observed from the outside.

Lesions of E. maxima comprise multiple petechial (pin-point size) haemorrhages often seen from the outside of the mid-gut area, in addition, segmental ballooning or enlargement of the mid-gut with presence of orange-tainted mucous may be noted. However, unless the lesions are typical they are harder to identify than those caused by E. acervulina and E. tenella and therefore it is highly desirable to confirm its presence by identifying the presence of coccidial oocysts (eggs) in a scraping from the mid gut under a microscope.

Gross lesions of E. tenella are confined to the caeca and consist of the presence of haemorrhages on the outside or inside of the wall of the caeca, free-blood or a chocolate-coloured fluid content inside the caeca with a thickening of its wall or the presence of a large core of cellular debris and blood. E. tenella can kill birds so dead birds in a flock with increased mortality should always be examined for the presence of lesions compatible with E. tenella infection or caecal coccidiosis.

Coccidiosis Treatmenta

In spite of our best efforts, cases of clinical coccidiosis may occur from time to time, according to Dr Cervantes.

This could be due to a variety of reasons. These include:

  • the feed mill inadvertently omitting the the anticoccidials drug or including too low a dose
  • the birds may have been offered the withdrawal feed for too long a period of the feed, or
  • the coccidia involved might have suddenly developed resistance against the drug.

Keep in mind that outbreaks of coccidiosis may also occur due to more indirect causes, warned Dr Cervantes, for example, birds that are immuno-compromised or with a deficient immune system (regardless of the cause) are more likely to suffer from outbreaks of coccidiosis. Also, if there is wet litter in the house, the high number of infective eggs may overwhelm the best preventive drug. Management practices that restrict access to light, water or feed – whether intentional or accidental – or increase stocking densities can also increase the problem.

Prompt resolution of the problem can prevent significant losses to the producer.

Key points to remember regarding treatment are:

  • Pick for treatment the drug most likely to be effective for the type of coccidiosis that you want to control
  • Ensure the water lines have been flushed and do not contain residues of other drugs or water-administered supplements (vitamins, electrolytes, etc.)
  • Sulphonamides are more stable and effective at neutral to alkaline water pH
  • Remember that the required withdrawal periods varies between sulphonamides, and
  • Be mindful of label directions and withdrawal periods to ensure efficacy and avoid tissue residues

Table 4 lists the drugs available for the treatment of coccidiosis in broilers, the manufacturer’s recommended dosages, duration of therapy and type of coccidiosis most likely to respond favourably

Table . Guidelines for Treatment of Coccidosis in Broiler Chickens1

Trade Name


trade Name

Active Ingredient

Dosage & Treatment Duration2

Type of Coccidiosis Most Likely to Respond Favourably




Amprolium+ Ethopabate



 Pioprolium dose is 30 mg for each Kg body weight in drinking water for 4-5 hours –for Pio-amoxi its dosage 0.5 gm / litres in drinking water daily for 8 days for 4 successive days

Early Notice of mild to moderate coccidiosis accompanied with Necrotic entritis 







Piolincneen dose is 20 mg per 1 kg Bw for 8 successive days while pioverdine dose is  ¼ to ½ gm per litre for 8 hrs for 4 days

Severe outbreak of coccidiosis accompanied with mild to moderate necrotic enteritis


Pio-Amoxi 50%





Pio amoxi dose is 30 mg for kg Bw for 4-5 hrs while pioverdin dose 0.25 to 0.5 gm per litres for 8 hrs

Severe outbreaks of caecal coccidiosis accompanied with severe necrotic enteritis



Pio-Amoxi 50%



Vitamin K


Pio amoxi dose is 30 mg per Kg Bw while piocoxin dose is  0.5 gm per litres for 8 hrs

severe  outbreaks of caecal coccidiosis accompanied with severe NE


1 Always read and strictly adhere to manufacturer’s label directions for use and withdrawal periods
2 Dosages per gallon of stock solution based on medicator set to dispense 1 fl oz/gallon of drinking water.


  1. Cervantes, H., 2002. Incidence of pathological conditions in clinically normal broilers from different regions of the USA. 51st Western Poultry Disease Conference, May 1-4, Casa Magna Marriott Resort, Puerto Vallarta, Jalisco, Mexico, 220-223.
  2.  Cervantes, H., 2006. Incidence of subclinical diseases and pathological conditions in clinically normal broilers from 3 production complexes sorted by sex and age. 143rd Annual Convention of the American Veterinary Medical Association and 50th Annual Meeting of the American Association of Avian Pathologists, July 15-19, Hawaii Convention Center, Honolulu, Hawaii.
  3. Johnson, J. and W.M. Reid, 1970. Anticoccidial drugs: Lesion scoring techniques in battery and floor-pen experiments with chickens. Exp. Parasitol. 28: 30-36.

Hector Cervantes, DVM, MS, Dip. ACPV is Manager of Poultry Technical Services for the North American Region for Phibro Animal Health Corp., based in Watkinsville, Georgia, USA.

Pathogen L1 L2 L3 L4
Eimeria acerviolina

white ladder-Like spots lesions in the duodenum

Lesions can extend much Further than the duodenum.

Intestinal wall is thickened and contains Liquieds.

Intestinal wall is lumen is white - grish color and seriosly inflammed


E. Praecox

Normal intestinal wall and the content is quiet liquid

intestinal wall slightly thickened and contain whitish mucus and non-digested Feed


E. Maxima

Small red petechiae on the serosal surface

Thickening intestinal wall and contain full of orange mucus

The intestinal wall is inflammed and thick -The serosal surface is wrinkled

The intestinal wall is thickned more than the double - it contain several bloody spots.

E. Necatrix

Small scattered petechine and white spots on the serosal surface

Several lesions. on the serosal surface with Light inflammation

External bleeding in the intestinal lumen and the serosal surface covered with red petechiae and wrinkled

Extensive bleeding and the intestinal content i's red or brown macus

E. Mitis

Normal intestinal wall and the content is Slightly Liquid.

The intestinal wall is slightly thickened and the content more creamy aspect


E. Tenella

Very Few petechiae on the Caecal wall

More lesions with blood in the caecal content with abit thickening caecal wall

The caecal wall is greatly thickened and Contain large quantities of blood

The caecal wall is strongly streched with blood with no caecal debris.

E. brunettae

No macroscopic lesions observed

The intestinal wall is greyish colour and thickened. There can be apsendo - membrane with Salmon points

Thickened intestinal wall with acatarrhal bloody exudate content

Extensive coagulative recrisis of the mucosal surface of the lowest part of the gut.

Humidity control

RH 55- 60 %

Initialhouse temp 32oc

Anticoocidial treatment control

Changing anti-coccidial drug group to another for boosing effectiveness of the treatment thnerapy

  1. Limited cross resistance between groups
  2. Strong cross resistance within groups.

If the ration includes ionophore switch to chemical anticoccidial if ration includes chemical, switch to ionophore based on the above resistance map by preview history.