Spotty liver
Spotty liver is one of the most common diseases in free range and barn laid egg laying chickens in Australia. The incidence of the disease has been steadily increasing as free range and barn-laid egg production increases.
Scientific name
Cause
Recently identified as a unique Campylobacter species.
Other names
- Summer hepatitis
- milliary hepatitis
Affected animals
- poultry
- chickens
Clinical signs
There are very few external signs of spotty liver. Often dead birds are in good body condition, but may be hot to touch, indicating fever. The crop is often full and some affected birds may show signs such as:
- droopiness
- ruffled feathers
- shrunken combs.
Egg yolk colour may also be lighter.
Post mortem results show many characteristic cream-coloured small spots (like millet seeds) in the liver.
Impacts
Often the first sign of disease is an increase in mortality when hens are in early lay, between 22 and 28 weeks of age. Mortality rates can be around 10% and egg production losses can be as high as 30%.
How it is spread
Wet litter has been identified as a contributor to outbreaks of the disease.
Stress factors such as hot-humid weather, overcrowding in shelter houses on the range, nutritional changes, inadequate feed space and cannibalism have also been proposed as contributors.
It is also spread through the oral-faecal route. Flocks can get it a number of times.
Risk period
Typically occurs in the hotter months of the year, but has been known to occur all year round. When hens are in peak lay is also a high risk time for the disease to occur.
Control
Improved husbandry, hygiene and biosecurity practices all help to prevent a spotty liver outbreak. It is important to keep hens in hygienic conditions, with minimal stress.
This disease responds to antibiotics, usually as a feed additive, which must be prescribed by a veterinarian. When using medications, any withholding periods must be observed.