Chickens are most susceptible to clinical disease when they are between 3 to 6 weeks of age. Chicks less than 3 weeks of age are still susceptible to becoming infected with the virus, but typically don’t demonstrate signs of illness. All chicks that are infected with the virus, regardless of whether they demonstrate clinical signs at the time of infection, have lasting impacts. The damage the virus causes to the cloacal bursa results in greater susceptibility to future infections, including normally nonpathogenic microbes.
When clinical disease occurs, in chicks 3-6 weeks old it is characterized as follows:
- Has a sudden onset and rapidly runs through all flock members.
- One of the first clinical signs is watery or whitish diarrhea that clings to the chick’s vent feathers (referred to as ‘pasty butt’). Sometimes blood is also present. Affected chicks are often seen picking at their own vents.
- General, non-specific signs such as lethargy, depression, loss of appetite, reduced water intake, huddling, ruffled feathers, and reluctance to stand soon follow.
- Diarrhea and reduced water intake leads to dehydration, soon followed by incoordination, trembling and weakness.
- 20-30% of chicks will usually die within 3 days from when they first developed signs of illness.
- Remaining flock members will usually undergo a rapid recovery 5-7 days later.
How Chickens get Infectious bursal disease
Infectious bursal disease is spread by direct and indirect contact with infected birds, often through exposure to feces. The virus is shed in the feces of infected chicks and can survive in the environment for several months.
Incubation period for Infectious bursal disease
The incubation period is very short, with clinical signs becoming apparent within 2-3 days following exposure to the virus.
Diagnosis of Infectious bursal disease
For live birds, the disease is diagnosed through serology, bursal histopathology or PCR testing. Necropsy results will often reveal bursae filled with pus or blood which are regarded as pathognomonic changes for this condition.
Treatment for Infectious bursal disease
Treatment consists of supportive care. Antibiotics may be indicated to help control secondary bacterial infections.
|Supportive care||Isolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken “intensive care unit”) with easy access to water and food. Limit stress. Call your veterinarian.|
|Treatment of pasty butt||When poop hardens it can cause a blockage to the chick’s gastrointestinal system, as if the poop has no way to leave the chick’s body, the chick will die.
Gather a warm wet facecloth, dry paper towels, and petroleum jelly (Vaseline).
Using the facecloth, gently run it over the hardened poop. The intent is to clean it off completely, but depending on how hard it is this may take repeated attempts and a little time. Once clean, gently dry off the chick’s bum with the dry paper towel and apply a small amount of petroleum jelly to the area that was sticky, to try to prevent fresh poop from sticking in the future. Repeatedly check on the chick, as this process is likely to need to be repeated.
|Protocatechuic acid (PCA)||20 mg/kg for 5 days|
|Thymulin 5cH||Diluted into drinking water||Sato C et al., 2012|
|Calendula officinalis extract||0.5 ml added to feed daily for for 7 days||S Marina et al; E Barbour et al|