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[ Systems | Husbandry | Nutrition | Food Sources | Diseases | Emergency Care ]
Diseases
The most important diseases are those that cause the highest mortality, can infect
people and endanger wild avian populations.
Zoonotic Diseases- The four most significant diseases are Psittacosis, Salmonellosis,
Newcastle's Disease and Avian Tuberculosis.
1. Psittacosis- The infectious organism, Chlamydia psittaci is spread by dust,
feces and direct contact. Affected parrots may have droopy eyes, inappetence, weight
loss, respiratory signs and lime green feces. The diagnosis is made by history, signs,
and blood or fecal tests. Cockatiels, budgerigars and lovebirds may harbor the disease
and be asymptomatic carriers. Diagnosis of Psittacosis in these small birds has been
much more reliable using new DNA technology.
2. Salmonellosis- Salmonella is usually spread by fecal contamination and
direct contact. The sources of this infection are many and include a filthy environment,
bird to bird contact in overpopulated cages, contaminated foods, animal bites and,
human exposure. Signs of infection may include sudden depression, watery droppings,
rapid dehydration, anorexia and rapid death. Diagnosis can usually be made by signs,
history, blood tests, and cultures. Salmonella can be prevented if the bird is fed
clean, nutritious foods, housed in a clean cage and isolated from ill birds.
3. Newcastle's Disease- This particular strain of Paramyxovirus-1 can be a
deadly disease of poultry, pigeons and doves and of psittacines. In parrots, it typically
causes causes neurological and respiratory signs. The presence of Newcastle's Disease
in the U.S. is very low but ocurrs occassionally due to smuggling of infected Amazon
parrots from Mexico. Diagnosis can be made by isolating the virus and by blood tests
of affected birds. Treatment is not recommended due to the likelihood of developing
carrier birds which may pose a threat to poultry flocks. Preventing spread of the
disease is through depopulation of infected birds. Outbreaks in the poultry industry
in the U.S. have proven to be economically devastating.
4. Avian Tuberculosis- Avian Tuberculosis (Avian TB) is caused by the bacteria
Mycobacterium avium. Birds exposed to high numbers of Avian TB organisms may become
infected more easily. Birds which are "blown fed" (chewed food is spit
into the baby bird's mouth) and therefore exposed to M. avium, will often develop
the disease later in life. The most commonly blown fed birds are members of the Brotogeris
family and include: Grey-cheeked Parakeets, Canary-winged Parakeets and Orange-chinned
Parakeets. Amazon parrots and macaws are also at risk. These birds are endemic to
areas of South and Central America and Mexico where people infected with Avian TB
may pass it along to them. Signs of advanced tuberculosis include poor plumage, feather
loss, weight loss and gastrointestinal problems. Often, birds may remain asymptomatic
carriers for years while shedding the disease in their feces. Diagnosis is made through
an acid-fast stain of fecal matter. People at risk of contracting Avian TB are those
with compromised immune systems. Most avian veterinarians do not recommend treatment
because of the zoonotic potential. A few practitioners advocate treatment since current
therapies may prevent shedding of the bacterium. Few people, however, follow through
with the treatment protocol since it may take years to eliminate the disease completely,
the diagnostic tests are costly and the birds require daily treatment.
Non-zoonotic Diseases- The most common diseases encountered by veterinarians
are those resulting from poor husbandry.
1. Obesity- As previously noted, obesity has been associated with fatty liver
disease, egg binding and hypovitaminosis A. Diagnosis is easy, treatment may be difficult.
Limiting a bird's diet is easiest but may lead to starvation. Gradual weight loss
can usually be achieved by adding fruits and vegetables to the diet as well as dry
foods such as pellets, pastas and cereals. Always supplement the bird with vitamins
in any weight loss program.
2. Malnutrition- Another preventable disease, malnutrition often manifests
as low calcium levels and pathologic fractures, hypovitaminosis A and oral abscesses,
lysine deficiency and yellow or white plumage, plumage stress bars from multiple
deficiencies and emaciation from low caloric intake. A balanced diet is all that
is required.
3. Polyomavirus and Psittacine Beak and Feather Disease
Syndrome- The
former manifests in two primary forms. The first is sudden death, anemia and bruising
in young and baby birds. The second resembles Psittacine Beak and Feather Disease
Syndrome (PBFDS) and both diseases may result in feather dystrophy in young and mature
birds. For PBFDS, signs may be as mild as a lack of powder or a shiny beak on a cockatoo
or as severe as beak decay on a bird completely devoid of plumage. Diagnosis is made
by a feather and follicle biopsy or by a DNA probe test which is performed on blood
sample. A vaccine has been developed for Polyomavirus which has been shown to be
very protective in psittacine birds. PBFDS can be eliminated from the aviary through
testing and removal of affected individuals.
4. Candidiasis- This gastrointestinal disease is caused by a yeast known as
Candida albicans and is usually a problem in handfed baby birds. The cause is often
a dirty environment, contaminated foods or feeding utensils, and improper handfeeding
technique. Diagnosis of Candidiasis or "Thrush" is rather easy since the
babies often have a thickened crop, a sour odor to the breath and are passing minimal
droppings. The organism is readily visible microscopically on crop or fecal tests.
Treatment is with Nystatin, an oral anti-yeast medication or "azole"-antifungals.
5. Aspergillosis- Aspergillosis is caused by Aspergillus niger, A. flavus,
or A. fumigatus which are fungi. It is usually a respiratory disease which may form
abscesses in the airsacs, lungs and trachea. Signs are voice changes, exercise intolerance,
tailbob, respiratory discomfort and ocassionally neurological signs. Diagnosis is
by blood tests, X-rays and cultures. The prognosis is often poor since avian patients
seldom react or respond to the infection. It is as though their body doesn't recognize
the fungus is present. Aspergillosis is contracted from living in a warm, wet, dirty
environment where fungal spores are present or through aspiration of food during
hand feeding. Treatment is very difficult and the prognosis is poor. Some success
has been with oral antifungal agents, inhaled and intravenous antifungal agents and
surgery to remove the abscesses.
6. Parasitism - Protozoa, coccidia, roundworms and tapeworm infections are
common and result from keeping multiple species in one aviary and permitting reinfection
from fecal matter. Diagnosis is by microscopic examination of feces. Treatment for
each is specific but unrewarding unless the primary problem of fecal contamination
is addressed.
7. Egg Binding- Hypocalcemia, obesity, and lack of exercise predispose hens
to binding eggs and laying soft-shelled eggs. Diagnosis is by physical examination
(palpation of the egg) or radiography. Treatment consists of calcium supplementation,
uterine stimulation and extraction of the egg externally or surgically. Prevention
is by maintaining the bird on a high calcium diet balanced with phosphorus and vitamin
D and allowing exercise in larger cages. Hormones are often used to cease the hormonal
cycling in hens.
8. Bacterial Infections- Most bacterial infections in birds are the result
of poor husbandry and human contact. Birds possess a Gram positive bacterial flora
and if overwhelmed by Gram negative bacteria, may become ill. Mammalian bacteria
is, for the most part, Gram negative. Kissing a bird with wet kisses or allowing
it to pick food from your teeth will predispose them to enteric infections. Prevention
is simply through good sanitation.
9. Heavy Metal Toxicity- Birds are highly sensitive to the deleterious effects
of lead, zinc, and other heavy metals. Lead and zinc typically cause neurological
and gastrointestinal signs such as dizziness, droopy eyes and metallic green feces
or bloody feces. Diagnosis is confirmed by radiographs or blood lead levels and treatment
is with an injectable drug called Calcium EDTA. Newer oral medications are being
tried to increase survival. If caught in the early stages, the prognosis is usually
good.
[ Systems | Husbandry | Nutrition | Food Sources | Diseases | Emergency Care ]
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