Avian Influenza is a highly contagious viral disease affecting the respiratory, digestive and/or nervous systems of many avian species. Avian Influenza is commonly spread by migrating birds and waterfowl. Waterfowl are resistant to disease and rarely show clinical signs when infected. Avian Influenza is shed by infected birds in their faeces and respiratory discharge and can also be spread via fomites, such as contaminated equipment, vehicles or people.
There are many strains of Avian Influenza which are divided into two types: highly pathogenic Avian Influenza (HPAI) and low pathogenic Avian Influenza (LPAI).
HPAI causes severe disease with sudden mortality of up to 100%.
LPAI can cause a range of symptoms, from mild respiratory disease, depression and a decrease in egg production. Birds infected with LPAI may not show any symptoms.
Other symptoms may include swelling of the head, cyanosis (blue discolouration) of the comb and wattle, nervous signs, such as paralysis, and/or green diarrhoea.
Diagnosis cannot be made on history, clinical signs or post-mortem alone. Blood sampling or virus isolation is required for a definitive diagnosis.
There is no treatment for Avian Influenza.
As Avian Influenza is a notifiable disease, if you or your vet suspects Avian Influenza, this must be reported to the APHA, who will investigate the outbreak and conduct statutory testing and implement restrictions and control measures as necessary.
If a notifiable disease is confirmed, action will be taken on infected premises to reduce the risk of the disease spreading, including movement restrictions. Other actions, such as culling affected and susceptible birds, restrictions on premises the disease may have spread to and from (for example when animals have been moved), disinfection protocols and restrictions on activities such as shooting may also be implemented.
Outbreaks usually occur following introduction by infected migrating or imported birds.
Biosecurity measures are the most effective protection against Avian Influenza. This includes cleaning and disinfection of equipment, vehicles and houses. Site-specific protective clothing and footwear and disinfectant foot dips are also useful biosecurity measures to prevent infection. Foot dips must be covered and regularly changed.
Preventing contact with wild birds is crucial to preventing Avian Influenza. Keepers of waterfowl should try to discourage contact with wild birds and wild waterfowl. The virus survives well in ponds and lakes.
Injurious pecking/ Mating trauma
Feather pecking and aggression between gamebird poults and breeders (pheasants and partridges) has a significant impact on bird welfare and plumage quality. Pecked birds will be stressed and therefore less productive and birds with inadequate feather cover are unsuitable for release due to the likelihood of them chilling in bad weather.
Feather pecking may be classified as:
Gentle or severe feather pecking is usually redirected ground pecking and when severe this can progress to cannibalism.
Vent pecking usually begins at the beginning of egg laying and involves pecking directed at the cloaca. It usually starts as an investigative behaviour, which may progress onto cannibalism.
Cannibalistic pecking usually involves a group of birds attacking an individual. These birds ingest skin, tissue and organs from the victim and it usually results in death.
Aggressive pecking is always directed at the head and is associated with birds establishing social order.
Trauma/aggression during breeding:
Male on male aggression: males will fight for the right to mate females and can cause severe injury to one another.
Male on female trauma: given to a female during copulation.
Lameness from mating.
Egg cannibalism: this is a learned behaviour and can be passed between birds as they receive a nutritional ‘reward’ from cracking and eating eggs.
Contributory factors that can lead to feather pecking or aggression:
High stocking rates.
Inappropriate Male: Female ratios for breeders.
Avoid high stocking rates and overcrowding.
Provide clean, fresh water to the birds. Drinking water quality can quickly and easily be tested; ask your vet for a water sample kit and collect a sample from the birds drinking water.
Ensure an adequate, balanced diet. Changing the birds onto different diets should be done as gradually as possible to prevent disruption to bacteria in the birds digestive system; for example when switching pheasants in rear from a rearing pellet to a wheat based diet ready for release, wheat may be offered to birds alongside the pellets whilst the pellets offered are gradually reduced over a two to three week period, allowing the birds to slowly transition onto the new diet with minimal impact on the gut bacteria, reducing stress.
Pre-empt stressful events, such as diet or environmental changes, where possible and speak with your vet about ways of reducing the impacts of such events on your birds. There are a range of supplements that may be recommended on an individual basis to enhance intestinal function, reduce stress and optimise bird health.
Optimise environmental enrichment. Pheasants roost in trees and partridges use high ground to observe the environment in the wild, perches can allow for this natural behaviour. Maximise open floor space to provide opportunities for natural foraging behaviour where possible. Including perching from an early age will also allow birds to escape from one another during pecking outbreaks.
Isolate any birds with bleeding injuries, that are slow growing and that show signs of disease at the earliest opportunity.
Avoid early onset of lay where possible and provide nest boxes that minimise the visibility of the cloaca to other birds during egg laying.
In breeder pens, assess the ratio of males: females. If too many males are present there will be increased incidences of male on male aggression.
If damage to the females is severe then the option of a ‘pheasant saddle’ may be used to protect the bird.
Discourage egg cannibalismduring breeding by providing an enclosed space for hens to lay eggs in. Should this proof ineffective some ‘spectacles’ may be put in place on offending birds during the egg laying period to reduce the temptation to destroy eggs.
Beak trimming should not be practised in gamebirds as they are to be released into the wild and require intact beaks.
Bits may be used for short periods of three to seven weeks if required. Management devices should not be considered as routine as it is important for birds to be able to express natural behaviours; any type of device that is designed to pierce the nasal septum is illegal in birds.
Get in touch with your vet at the earliest opportunity if you have a problem with feather pecking to minimise the issue as quickly as possible and optimise the welfare, health and condition of the birds.
During the summer of 1994, an outbreak of disease resulted in the rapid death of over 1000 breeding pheasants at a game farm with approximately 7000 birds. This was caused by a type of ‘coronavirus’ that is distinctly different from the respiratory coronavirus of birds known as ‘Infectious Bronchitis’.
All birds are susceptible, but the most severely affected are young birds. However, the majority of cases are seen in breeder birds.
ACUTE symptoms: sudden mortality (as high as 50%), decreased food intake and white diarrhoea.
CHRONIC symptoms: sneezing, decreased egg production and reduced hatchability.
Post mortem examination will show;
pale, swollen kidneys
visceral gout may be seen in some birds
PCR on affected tissue/ respiratory tract will determine infection.
Targeted antibiotic therapy using culture and sensitivity may help control secondary infections but will not help birds recover from the virus itself.
Supportive electrolytes through the water will help birds keep rehydrated and so have a greater chance at recovery.
Prevention and Control
Routine cleaning and disinfection; The virus can be easily destroyed by heat, lipid solvents, nonionic detergents, formaldehyde, oxidizing agents and UV irradiation. 1% solution of formalin & 0.5% peracetic acid seems to be effective.
Vaccination either in the water or by eye-drop. The vaccines available are designed for use in chickens so are used off license.
Biosecurity between houses; footdips, changes of clothing/ footwear will help reduce spread between different groups of birds as the virus spreads by airway secretions and faecal contact.
Optimising the birds environment will help reduce spread and decrease stress;
Reducing stocking densities (specifically assess the male:female ratio in breeder pens).
Ensuring birds have adequate access to food and a clean water supply (including sanitisation – ie. hydrogen peroxide, chlorine etc).
Ventilation; Controlling ammonia levels within the housing.
Using appropriate shed temperatures
Looking for and controlling any pre-existing diseases; like Coccidiosis