GOT
A BIRD WITH A RESPIRATORY INFECTION? HERE’S WHAT TO DO
By Dr Colin Walker BSc, BVSc, MRCVS, MACVSc
(Avian health)
As veterinarians, one of the most common presenting problems in
birds is respiratory infection. Birds on presentation display a
variety of symptoms, including sneezing, red watery eyes, discharge
from the eyes and nostrils, and swollen sinuses. Many veterinarians
may prefer to refer such patients to avian vets. However, below
is set out a quick summary of the way this problem could be approached.
Chickens
In chickens, respiratory infections can be divided into two groups,
those caused by bacteria and similar agents and those caused
by viruses. The viral diseases are Infectious Laryngotracheitis,
Infectious Bronchitis, Newcastle Disease and Avian Influenza.
These all have high morbidity and/or mortality rates. The diseases
in the other group are Infectious Coryza (Haemophilus Infection),
Fowl Cholera (Pasteurella Infection) and Chronic Respiratory
Disease or CRD (which is due to a combination of Chlamydia, Mycoplasma
and E. coli). By far, the most common is CRD and in fact this
probably accounts for more than 80% of all pet chickens presented
with respiratory signs. So how is this disease managed? Remember
(as with many bird diseases) that there is a stress component
so that, for control, not all of the answer will be the use of
medication. CRD can be managed with a 3-point plan:
Revise housing, management and nutrition with the owner to identify
any faults here.
Perform a crop flush and faecal smear to check for concurrent disease,
in particular parasitism. Flagellate infections in the throat are
common, as are worm and coccidial infections. These will need to
be treated if a good response to antibiotic treatment is hoped
for. Flagellate infections can be treated using Flagyl (metronidazole)
200 mg, ¼ tablet / 2 kg once daily for individual birds,
or Turbosole (ronidazole), 1 teaspoon / 2 litres of water if large
numbers of birds require medication making individual treatment
impracticable. For Coccidia, use Baycox (toltrazuril), 3 ml to
1 litre for 48 hours, or 0.2 ml / kg once daily for 2 days to individual
birds. To treat Ascarids and Capillaria worms, Moxidectin 2 mg
/ ml, 5 ml to 1 litre for 24 hours, or 0.5 ml / kg once works well.
Treat with doxycycline. Do not use other tetracyclines as they
maintain too short blood levels (eg oxytetracycline and chlortetracycline,
about 4 hours) for effective treatment and their absorption is
significantly interfered with by a variety of mineral salts and
other substances that are routinely ingested by free-range pet
birds. Doxycycline maintains circulating blood levels for approximately
20 hours after medication and its action is affected to a lesser
extent by mineral salts. Doxycycline is available as Vibravet tablets
50 mg, 1 tablet / 2 kg daily to treat individual birds, or, to
treat larger numbers of birds, as a water-soluble powder, Doxyvet
(doxycycline 12%), 1 teaspoon / 2 litres mixed fresh daily. Continue
until all birds are well.
Pigeons and parrots
As with chickens, more than 80% of respiratory infections are associated
with either Chlamydia or Mycoplasma. Most birds carry these organisms
in their system all the time and are passively infected by their
parents in the nest. In otherwise well birds, these organisms
rarely cause disease but rather the ongoing low level of exposure
to the organism enables the development of a strong natural immunity
that is sufficiently high to provide protection from disease
in most birds by 6 months of age and in almost all birds by 12
months of age. As with chickens, to ensure a good response to
treatment, it is important that any flaws in environment or management
are identified and corrected and that any concurrent disease
is treated. The antibiotic of choice once again is doxycycline.
Birds are treated until they are well, with treatment courses
of 5 - 20 days being common. In theory, if birds are treated for
45 days with doxycycline, it is possible to clear Chlamydia from
their systems. However, it is probably not in the birds’ interest
to consider these long treatment courses. Birds need ongoing low-grade
exposure to the organism to maintain immunity. If the Chlamydia
was cleared, the bird’s level of immunity would quickly wane,
leaving it vulnerable to disease if it ever re-encountered Chlamydia.
Given the ubiquitous nature of the organism, if it ever came in
contact with another bird or bird dropping, then this is likely.
Sometimes birds are pulse treated. Here birds are given shorter
follow-up courses of medication (often 3 - 4 days every 2 - 3 weeks)
after their initial longer course of medication. This protocol
keeps the organism under control while the birds establish their
natural immunity. Often after several treatments medication can
be withdrawn with the birds remaining well. Small numbers or individual
birds may be treated with oral doxycycline tablets, eg Vibravet.
In some pet birds, repeated handling for medication causes significant
stress and the risk of injury and here water-based medication is
an efficient easy owner-friendly way of providing treatment. Where
larger numbers of birds are involved, water-soluble medication
is the only practicable treatment. In these instances, a water-soluble
powder such as Doxyvet may be used. |