Gerneral Health and Common Diseases

Avian Influenza

Avian influenza must be the most discussed poultry disease of the recent decade. The great concern has been the possibility of a human flu virus mixing up with a deadly bird flu virus leading to a virus which has the ability to infect humans and the mortality causing potential of an avian virus. But luckily so far this has not happened although there has been many minor cases and huge number of birds slaughtered with avian flu to try to reduce infection spread. As with salmonella, AI is a vast subject outside of the remit of this short disease guide. However, the important fact to remember is, if you have sudden high mortality of unknown cause then contact your vet immediately for advice. Do not take birds or send birds for post mortem as this might spread disease. Avian influenza can be very deadly, although there are mild strains with little signs.

For more information on this and other poultry issues please visit The Chicken Vet



In order to grow healthy chickens to desired targets, giving them a good start is essential. Often the chick’s specific requirements are not met; therefore with a little more understanding this is an area that can often be greatly improved. It is important to know what a house of contented chicks look like in the first instance. This will enable the grower to evaluate the chick environment and make any necessary alterations. Chicks should be eating, some drinking, some playing and resting, with an even spread on the floor. The chicks should be making a contented chirping, not silent and not high pitched.

For more information on this and other poultry issues please visit The Chicken Vet


Cleaning and Biosecurity

When cleaning a small chicken coop, the advice given to larger farms still applies but it can be difficult to decide which product to use. For simplicity we suggest: Always wash with a detergent. This can be as Liquid Smite or Total Mite Kill, which will also have an anti red mite affect. Cleaning and removal of organic material is very important. After the shed is clean , let it dry When dry a your chickens can be aload to go back in the coop.


A common disease caused by a parasitic protozoa which damages intestines resulting in poor performance and mortality. It affects chickens, ducks, turkeys, geese, game birds and many other species of animals. Birds tend to show characteristic signs of ruffled feathers and a hunched posture. It is spread by litter/droppings from affected birds, equipment, humans, wild birds/animals and poor hygiene. It thrives in warm, damp conditions.

Egg Quality in Laying Chickens

There is nothing more rewarding than picking up a warm, fresh laid egg with a clean, smooth shell and then cracking it to reveal a rich, yellow yolk and a clear, firm white. However, this is not always the case and there are various reasons, usually connected to disease or stress to explain why defects may arise. These may be internal or external. The older a hen gets the more likely there will be egg quality issues and fewer eggs laid; this is quite normal. 

Infectious Bronchitis

Infectious bronchitis is caused by a corona virus which leads to damage of the upper respiratory tract and oviducts. The virus can also infect the intestine and kidneys. There are many different strains and the virus works with other pathogens to cause disease in the bird. In layers, infectious bronchitis can cause: Egg drops. Poor egg shell quality. Respiratory disease and death.


A chicken herpes virus affecting chickens and turkeys. Birds are at risk as soon as they hatch. Incubation period is 6 – 8 days following a viral challenge but clinical signs may take weeks to appear. Vaccination usually takes place at hatch. The chick needs 7 – 10 days post vaccination for immunity to establish. Vaccinated birds may still contract Mareks if they are exposed to an extreme challenge. 

 Red Mite Infection

An external parasite of chickens and turkeys, although very small can be seen by the naked eye. The mite feeds by sucking blood from its host causing irritation. Birds can be restless and lethargic when heavily infested. Drop in egg production. Loss of condition from depressed feed intake. May cause anaemia and death in young birds. Skin irritation to humans.



Yolk sac Infection

The yolk sac is the remnants of the yolk from the egg which is absorbed by the chick into the abdomen and is a food source lasting for 3-5 days post hatch. The nutrients and antibodies within the yolk sac are absorbed and utilized by the chick. The yolk sac is attached to the navel and via this route infection can enter. Due to the being full of nutrients, any bacteria which gain entry can develop rapidly and lead to the death of the chick.


We have reviewed elsewhere the red mite parasite, these are the main surface parasites of chicken and their treatment. Although red mites are probably the most important and severe parasite of the skin of the bird, lice are also irritant and can be treated in the same way as red mites. Parasitic worms are another very important consideration and should be treated routinely. 

Egg Peritonitis

This is probably the most common disease of chickens and is a result of an egg yolk initially moving into the abdomen rather than being "captured" by the fimbrae at the top of the oviduct. In a normal egg cycle, the ovary releases a single ovum (yolk) which is picked up by the fimbrae at the top of the oviduct. The bird only has one oviduct and the egg passes down through the oviduct picking up albumin (egg white), the egg membrane and then the egg shell, before being passed out through the cloaca. The cloaca also has the ureters from the kidneys and the rectum passing urine and faeces through the same exit point. In birds coming into lay and birds which are stressed for various reasons there is the possibility that the ovum moves into the abdomen where it can create a sterile chronic inflammatory reaction which looks similar to scrambled egg when examined on post mortem. The bird will become ill from the reaction and may die. As the oviduct leads to the rectum, it is also possible for bacteria to move retrograde up the oviduct and infect the egg peritonitis leading to a bacterial peritonitis which is very difficult to successfully treat. The bird is depressed with a swollen hard abdomen and will often die whatever the treatment.

Sour crop

Sour crop is a condition of yeast infection in the crop leading to thickening of the crop wall, dilation of the crop and birds losing condition and possibly dying. The cause is often difficult to determine but you should check the condition of the feed store and always ensure birds have fresh feed. Treatment is also difficult as there is no specific treatment for sour crop. The use of copper sulphate has been successful but this must be carried out under veterinary supervision. Manually emptying the crop is difficult and the underlying fungal / yeast infection needs to be controlled. The crop can also become impacted in which case removing feed and manually massaging the crop is of use. In many cases a dilated crop is difficult to treat and the prognosis is not good.