Health & Disease


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Diseases Overview

Common Infectious

Common Non-Infectious


Notifiable Diseases

Disease Chart

Health Oracle

Diseases Overview

The birds you have bought will probably have been vaccinated against some of the more common poultry diseases (but ask in any case) and as long as they are fed correctly, stress kept to a minimum and are wormed at least twice a year, they should be healthy. Never buy a hen which has a runny nose or noisy breathing. My Diseases Chart (click on link in lefthand menu) is a summary of common poultry diseases found in small flocks. It is essential to involve your veterinary surgeon if you have problems with your poultry and although some wormers and louse powder can be obtained through licensed outlets (such as agricultural merchants), most drugs and medicines are only obtainable through a vet. Wash hands after handling medicines and observe the withdrawal instructions on the labels of drugs, so do not eat eggs (7 day withdrawal time) or birds (28 day withdrawal time) during and after medicines have been given. If medicines are given in water, make no other water available.

Most diseases are management related, for instance rats and mice carry some diseases as well as all those carried by wild birds, therefore many diseases can be prevented by good management. If you acquire birds which have not been vaccinated, should you vaccinate them? If there is a problem in your area of a specific disease, then it would be sensible to vaccinate them against that disease, but if you only have a few birds with no problems in the area, it will probably be all right not to vaccinate. The vaccines come in industrial sizes and so 95% of them would be wasted in order for your few birds to be protected. If there is a local disease problem, then it is money well spent. Unfortunately, vaccines can only be given to very young chickens to be effective, it is not possible to vaccinate adult chickens successfully, so there is a slight disease risk of mixing vaccinated and unvaccinated chickens.

Signs of diseases and prevention
Chickens are prey species and so hide their symptoms if they are sick. A change in behaviour is often the first sign that the observant owner sees.

A sick chicken will stand with its feathers ruffled and its eyes closed to conserve energy, by which time veterinary attention should be sought.

Sick hen

Veterinary attention is needed if the following signs occur:

  1. Foam in the corner of the eyes, swollen sinuses and nasal discharge: likely to be mycoplasma.
  2. Difficulty in breathing: respiratory disease.
  3. Lethargy, standing around with eyes closed: gut or egg laying internal problem.
  4. A change or blood in the faeces (remember the caecal faeces are different): possibly coccidiosis.
  5. The comb goes pale: likely to be red or northern fowl mites.
  6. The legs become rough with white raised areas: likely to be scaly leg mite.
  7. Lameness: if the chickens have been regularly wormed with Flubenvet, may be Marek’s disease.
  8. Unusually shaped eggs.

A decision tree of when you should contact your vet about your chickens has been built by this author and will be available here soon.


  • Poultry healthy respiratory system depends so very much on good ventilation that disease can be prevented: damp stale air will quickly cause problems
  • High levels of ammonia from the litter stop the removal of phlegm and so invite bacteria and viruses to multiply – if ammonia can be smelled in the hen hut, there is too much, so clean out the litter more often and increase the ventilation
  • Hens are omnivorous and enjoy catching and eating mice, but the disease risk is high from rodents. Not having teeth with pieces of food being ground up in the gizzard, old long grass needs avoiding as this can impact and kill, as can polystyrene (e.g. ceiling tiles) which they just adore to peck at, or pieces of plastic string
  • Stale or mouldy feed contributes to sour crop which is a yeast infection. Feed must be finished by the use-by date which is on the bag label. If you obtain feed in unmarked plastic bags, please enquire as to the use-by date which is generally three months after manufacture. Cider vinegar in the water (10ml:500ml, plastic drinker only to avoid zinc toxicity) one week a month is useful.
  • Muddy areas encourage harmful parasites to breed so put down slats or move the hut more regularly
  • Hens have evolved to scratch around in the dirt, but over a wide area. Problems occur if they are kept on the same small area of ground all the time which then becomes “sour” and harbours harmful parasites and other pathogens
  • Feathers are good insulators and it is sometimes harder to keep birds cool in summer than warm in winter. Birds that are too hot will hold their wings out from their body and pant.
  • Hybrids are automatically vaccinated against Infectious Bronchitis virus. Other backyard hens are only vaccinated if a disease has been diagnosed by your vet.

Information on Suprelorin implant

The Suprelorin implant has been developed and is licensed for controlling fertility in male dogs, a temporary and reversible “castration”. It does not seem to control crowing in cockerels, however! It is a vet-only product and has been used off-label (not licensed) in laying hens, particularly ex-batts, for the prevention of laying if they are suffering from egg peritonitis or prolapse. It is quite expensive and only lasts for about three months, so is a temporary solution, although allowing the regrowth of feathers without the stress of laying. The needle used for implanting this device which slowly releases anti-reproductive hormones is huge and needs to go in the breast muscle of the hen.

The problem of what to do with an affected hen is merely being postponed by using these implants, but at least it is a kind of solution until the welfare of the hen becomes untenable. These implants can be repeated but there is nothing more suitable available, short of getting a different type of laying hen which is less likely to develop these problems.