Fowl pox

Fowl pox is a viral disease in chickens, caused by an avian poxvirus. The virus spreads mainly through blood-sucking insects such as mosquitoes and other biting insects. As a result, infections occur mostly in spring, summer and autumn, when these vectors are most active. Infection can also happen through direct contact with lesions or scabs, or through contaminated material in the environment.

The disease can present in several ways. In the cutaneous or skin form, typical pox lesions appear on the unfeathered skin, such as around the eyes, on the comb, the wattles and sometimes the legs. These lesions often start as small raised bumps and can develop into crusty, wart-like growths. Depending on their location and severity, they may interfere with the bird's sight, feeding or general wellbeing.

In the diphtheritic or mucosal form, lesions develop on the mucous membranes of the beak, throat, oesophagus and upper respiratory tract. This can lead to a white-yellow coating or pseudomembranes in the mouth or throat. Birds may then have more difficulty eating, swallowing or breathing, and sometimes show reduced appetite, breathing difficulty or general weakening. This form is usually more serious than the skin form.

A coating in the mouth is not specific to pox, however. Other conditions can cause similar lesions, such as trichomoniasis, herpesvirus infections and, to a lesser extent, Candida infections. With lesions in the mouth or throat, a correct diagnosis is therefore important to establish the true cause.

The severity of symptoms can vary widely. Some birds show only limited skin lesions and recover on their own, while others become seriously ill, especially when there are also secondary bacterial infections, a high infection pressure or additional health problems. Young birds and birds with reduced resistance can be more prone to a severe course.

In an acute pox infection or outbreak, a quick response is important. Sick or weakened birds are then treated mainly supportively, with attention to their general condition, their food and water intake and the prevention of further complications. Additional support, for example with multivitamins such as Vita-Plus (NeorniPharma), can help carry the birds through the infection period. Because the virus can spread further within a group, it is often advised in such situations to emergency-vaccinate the entire group as well.

For preventive protection, pox vaccination is ideally carried out in May–June, that is, before the peak of mosquito and insect activity. Vaccinating later in the season still makes sense, however, especially when birds were not yet vaccinated in spring. Since pox outbreaks can still occur in August, September or later in autumn, vaccination at a later point is often still useful.

Vaccination against pox is possible from 4 weeks of age and is given by the wing-web method. Two vaccines are available: one against pox alone, or a combination vaccine against pox and ILT (infectious laryngotracheitis). Alongside Marek's vaccination in chicks (see blog), annual pox vaccination combined with ILT is the gold standard in hobby poultry.

In practice, it is common to wait until the youngest birds in the group have also reached this age, so that all birds can be vaccinated together. This is also practical, because once reconstituted the vaccine must be used within 2 to 3 hours and cannot be kept for use the next day.

For birds kept outdoors or in an environment with many blood-sucking ectoparasites, timely vaccination is strongly recommended. In high-risk situations, we usually advise vaccinating birds at 4 weeks of age, followed by a revaccination 3 months later. After that, an annual revaccination is generally enough to maintain protection.

At Neorni you can come to us for advice, diagnosis and vaccination against pox in chickens and other birds. If in doubt, a poxvirus infection can be confirmed through targeted laboratory testing at NeorniLab.