Infectious Coryza is a common acute respiratory disease that can affect chickens Australia wide. The medical fraternity uses coryza as a medical term for the common cold, but coryza can be more debilitating to chickens than the common cold usually is for humans. Read on to find out how to spot Coryza symptoms and treatments.
What is Coryza?
Coryza is an incredibly infectious virus found the world over, but it only infects chickens and cannot be passed on to humans. Symptoms of coryza include nasal discharge, swelling of the face and eyes, and sneezing. Chickens of all ages are at risk of the disease, but older birds are more susceptible to infection.
The incubation period for the disease is 2 to 3 days, with the disease able to maintain a presence over a 2 to 3-week period. If birds are suffering from other afflictions such as mycoplasmosis, then the duration of infection may be a little longer.
Coryza is not as terminal as other chicken maladies such as lymphoid leucosis, but for young chicks with an immature immune system and older weaker birds, it can be quite deadly.
The onset of coryza symptoms are rapid and manifest over a period of 2 – 3 days, so it is entirely possible for the flock to become infected in around ten days. With such a fast and brutal incubation period it is unlikely you will notice anything amiss with your birds until the disease is in full swing. Some birds may seem to have a lousy appetite, but this won’t be enough evidence to trigger a correct or rapid diagnosis.
For the most part, coryza is an acute disease, but once a flock is infected, every bird will remain a carrier for its entire life.
How do Chickens Catch Coryza?
The human cold virus is a viral infection, but in chickens, coryza is the result of the bacterium Avibacterium (Haemophilus) paragallinarum.
The disease can spread throughout the flock via many mechanisms including contaminated feed, bedding, floating dust particles, and infected droplets. The most likely places for the disease to spread throughout a region include live bird markets, poultry shows, and swap meets, or anywhere where birds from different flocks are gathered together.
In some cases, the disease may have infiltrated your flock by way of wild birds, so chicken keepers should make attempts at minimising contact with outside species. Chicks cannot be born with the disease as it has no means to pass through the egg, but young chicks are highly susceptible if they encounter an infected bird soon after hatching.
A clean coop that is not overcrowded can help reduce the incidence of coryza. Unclean, crowded coops provide ideal conditions for the bacterium to thrive and spread. Coryza is also an anaerobic bacillus, which affords it the ability to survive in oxygen-deprived environments such as chicken poop, soil, and water.
How to Know if Your Chicken Has Coryza?
Coryza symptoms share many similarities with other diseases when considered on their own, but when you notice them in combination, the condition is quite easy to recognise.
Coryza infects the sinuses in chickens, causing swelling, inflammation, and congestion in the upper airways and restricting breathing. Other symptoms you may notice include:
• A bird shows no interest in eating or drinking
• Pale comb – infection may sometimes result in swelling of the comb
• Breathing through an open mouth
• Difficulty walking
• A bird isn’t laying or has decreased egg production
• Possibility of diarrhea
• Eyelids may become crusty and stick together
A rancid, foul-smelling stench will also accompany the weepy eyes and runny nose of a bird suffering from coryza.
Because coryza stems from a bacterial infection, the usual and most effective course of action is to treat it with antibiotics. A course of antibiotics should only be prescribed by your vet, as incorrect use may cause more harm than good, with possible development of bacterial immunity against future treatments for other diseases.
Veterinarians will run a series of tests to determine the cause of your bird’s illness, so you can be sure that you are treating the correct malady with appropriate medication.
The most common antibiotics used to treat the disease are erythromycin, sulphonamides, or streptomycin. Most often the choice will come down to the level of availability, but in some areas, there have been reports that the bacillus has built up resistance to sulpha-based drugs.
Unfortunately, once coryza infiltrates your flock, any infected birds are carriers for life, so new birds you introduce are almost guaranteed to become infected if you haven’t vaccinated them. Of course, vaccination prevents the disease from manifesting, but treated birds are also carriers for life. If your flock has so far remained coryza free, any new birds should be quarantined for at least 30 or more days.
If you know you have a coryza outbreak, you should not visit any other chicken keepers while the infection is being dealt with. Likewise, you should not allow any owners of diseased birds to visit you either.
The mortality rate varies from flock to flock, but on average you can expect anywhere between 20% to 50% of your birds to expire from the symptoms.
The level of mortality can depend significantly on the age of your birds, with older birds more likely to succumb. Flocks experiencing poor nutrition, living in unhygienic conditions, or exposed to overcrowding will suffer a higher mortality rate, as will birds who are stressed.
Prevention of Coryza
Practice responsible chicken keeping by ensuring you wear different clothing when visiting other flock owners or attending shows, so there is no chance of the bacterium being transferred via way of your attire.
The bacteria responsible for coryza are susceptible to disinfectants, dryness and heat, so diligent and regular housekeeping is a must to ensure outbreaks are less likely. Keep your coop clean and ensure there is plenty of ventilation to prevent excessive moisture build-up.
A thorough clean out should also be conducted at least twice a year. Scoop up the poop every week and replace old bedding with dry, fresh material. The more frequently you do your housekeeping, the better off your flock will be.
Unfortunately, with birds travelling all over the country on a regular basis, coryza outbreaks are only going to become more frequent. Now that you know what to look out for you are in a better position to protect your flock and keep them healthy; not just from coryza, but from other chicken afflictions as well.