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Avian medicine
Avian medicine for the companion animal
veterinarian
Most of the birds kept as companion animals belong to the order of Psittaciformes and
Passeriformes. As a veterinarian working in a companion animal practice, it is thus very
likely to be confronted with birds from one of these orders at some point. During three
interactive lectures a diversity of subjects will be discussed that are relevant to the
companion animal veterinarian.
Nico J Schoemaker
DVM, PhD, Dip. ECZM
(Avian, Small mammal),
Dipl. ABVP-Avian
Y.R.A. van Zeeland
DVM, MVR, PhD, Dip. ECZM
(Avian)
Division of Zoological
Medicine, Department of
Clinical Sciences of
Companion Animals,
Faculty of Veterinary
Medicine, Utrecht
University
The Netherlands
N.J.Schoemaker@uu.nl
Y.R.A.vanZeeland@uu.nl
Anatomical and physiological considerations
The bird’s anatomy and physiology shows many unique adaptations, mostly related
to the ability to fly. Flighted birds have a light-weighted skeletal system, which
consists of a rigid and partially fused vertebral column and appendicular skeleton with
pneumatized bones, and powerful, well-developed breast musculature. In addition,
they possess highly adapted respiratory and circulatory systems to meet the birds high
metabolic rate and oxygen demand during flight. Another unique feature of birds is the
presence of feathers, which not only enable flight, but also play an important role in the
protection against elements and/or predators and communication with conspecifics.
Many species cannot be recognized based on external features (i.e., monomorphic
species), thereby necessitating the use of additional diagnostic tests to determine the
gender.
Psittaciformes (parrots and parakeets) are particularly well known for their speech and
ability to mimic sounds, which are produced in the syrinx, another specific feature of
birds. They furthermore are characterized by the hooked bill, which is extremely motile
and, together with the well-developed tongue, plays an important role in food intake.
After the food is swallowed, it is temporarily stored in the crop and periodically passed
down to the proventriculus and ventriculus. Both passeriformes and psittaciformes
have rudimentary caeca and generally lack a gallbladder. The digestive tract opens into
the cloaca together with the urinary and reproductive tract, of which only the left side is
developed in females.
Abstracts | European Veterinary Conference Voorjaarsdagen 2014
Nutrition, housing and care in captivity
Most birds are kept individually in cages, but may also be kept in pairs or group-housed
in an aviary. The size of the cage should be sufficient to allow the bird to spread its
wings fully. Number, shape and size of the available perches should be adapted to the
number of birds and species and placed in such a location that food and water are
easily accessible but not contaminated with faecal droppings. For parrots, enrichment
that stimulates natural foraging behaviour is considered important. Other enrichment
materials that may be provided include toys, ropes, branches and destructible materials.
UV-B lighting may be considered, especially in Grey parrots, to prevent hypocalcaemia.
The natural diet of most parrots and Passeriformes consists of seeds, nuts, fruits, berries
and other vegetation. Many species, however, also consume insects and/or larvae as
part of their diet, whereas other species, such as lories, predominantly feed on pollen
and nectar. Dietary deficiencies and concurrent disease are common. To prevent these,
it is recommended to feed parrots a pelleted diet, supplemented with fruits, vegetables,
nuts and seeds. Passerines are commonly fed a mixture of seeds and egg-food,
supplemented with vegetables and grit or sepia to provide them with extra calcium
(especially during the breeding season).
When purchasing a new bird, it is recommended to keep it quarantined for at least 4
weeks prior to introducing it to other birds. During this quarantine period diagnostic
tests for specific pathogens (e.g., Psittacine Beak and Feather Disease virus [PBFDV],
polyomavirus, chlamydia, helminths, flagellates and coccidia) should be performed.
When allowing a parrot or parakeet to roam free in the house, wing trimming may be
considered to prevent the bird from injuring itself (e.g., flying into a window). Other
grooming procedures include trimming of the nails and/or beak. Misting and/or
provision of bathing opportunities are also considered important to help maintain the
plumage in optimal condition.
Handling and restraint
Prior to handling any bird, doors and windows need to be shut. Dimming the lights
can facilitate the capture of small, anxious birds. The handling time should be kept to
a minimum as this may compromise the animal’s health, particularly in sick and easily
stressed birds. It is therefore important to have all the necessary materials ready.
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Physical examination and diagnostic techniques
Similar to dogs and cats, the physical examination starts with a thorough history
(including information regarding the complaint, husbandry, diet, living conditions,
general condition and behaviour of the bird), followed by an observation of the bird
from a distance (including an evaluation of the enclosure and the bird’s droppings)
and thorough physical examination (from head to toe) while the bird is manually
restrained. In dyspnoeic or weak birds, the physical examination is kept to a minimum
and primarily includes inspection of the beak and nares, determination of the body
condition, palpation of the abdomen, and auscultation of the heart and lungs. To
evaluate the birds’ condition, palpation of the breast musculature is combined with
checking the amount of food in the crop. All birds should be weighed routinely.
Following the physical exam, faeces, blood and/or swabs may be collected for further
diagnostic testing. Blood may be collected from the right jugular or ulnar vein using
a 26G needle and syringe. In general, a volume equalling 1% of the body weight or
less may be collected safely. Other diagnostic testing includes faecal examination
(cytology, wet mount, flotation), culture and sensitivity testing for bacteria and/or
fungal organisms, diagnostic imaging (radiographs, ultrasound, CT imaging or MRI),
endoscopy and collection of fine needle aspirates or biopsies for further cytological,
bacteriological, viral and/or histopathologic testing. The use of sedative agents and/
or anaesthetic gases (isoflurane, sevoflurane) reduces additional stress and greatly
facilitates the performance of these procedures. For short procedures, mask induction
is generally considered sufficient, but in larger-sized birds and longer procedures,
intubation and continued monitoring of the bird (e.g., using capnography and/or
electrocardiography) is recommended.
Medication techniques
In sick birds, the parenteral route is often used to administer drugs. Intramuscular
injections are generally administered in the pectoral muscles. Through the
subcutaneous route large amounts of fluids (20-50 ml/kg q8-12h) may be administered
in the precrural fold and/or between the shoulder blades. In severely debilitated birds,
the intravenous and/or intraosseus route may also be used.
Liquid formulations or (hand-made) suspensions are preferred when administering
drugs orally. The drugs can be given directly per os and/or administered into the crop
Abstracts | European Veterinary Conference Voorjaarsdagen 2014
(together with food) using rubber or metal feeding tubes. Medication of drink water
and/or feed is only recommended in case larger flocks need to be treated. Debilitated
birds often need to be gavage-fed. For this purpose, parrot hand-feeding formulas or
formulas specifically designed for debilitated birds (e.g., Emeraid, Lafeber Company,
USA) are often used. Volumes equalling 2.5-4% of the bodyweight may be given at
once, and provided 2-4 times a day.
For topical treatment, ointments or creams should be avoided if possible, as these may
compromise the quality of the plumage.
Common disorders
A variety of different viral, bacterial, fungal, parasitic, toxicologic, metabolic, nutritional
and traumatic conditions may affect psittacines and passerines kept in captivity. The
diseases to be considered in the differential diagnoses not only differ per species, but
often also depend on the way the bird is kept (i.e., housed indoors as an individual bird
versus outdoors in an aviary). The most common disorders affecting Psittaciformes and
Passeriformes are summed up in table 1 and 2.
Disease
Aetiology
Presenting signs
Diagnostic work-up
Aspergillosis
Aspergillus spp. (often
secondary due to
immuno-suppression
(e.g., hypo-vitaminosis A)
Mainly respiratory
signs, including acute
dyspnoea with stridor,
altered voice and open
beak breathing (tracheal
obstruction) or more
chronic forms
Definite diagnosis
requires cytology, or
isolation of the fungus
from samples obtained
from the respiratory tract
Avocado toxicity
Persin present in
avocado (already lethal
after ingestion of small
amounts)
Dyspnea, acute death
(cardiac failure)
History and post-mortem
exam revealing severe
lung edema, ascites and
cardiac necrosis
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Budgerigar fledging
disease or “French moult”
Budgerigars of 10-14
days of age: diarrhoea,
abdominal distension,
lethargy and acute
mortality; in older birds,
characteristic feather
abnormalities (lack of
primary feathers) can be
found. Adult birds are
often subclinical carriers
PCR (cloacal swab); postmortem examination
Various causes including
gastrointestinal
infections (e.g. Giardia,
E.coli, helminth
infection), neoplasia (e.g.
papillomatosis), egg
binding, behavioural/
hormonal causes,
neurologic deficits
Mucosa protruding
from the vent, often
associated with
dyschezia and/or
tenesmus; sometimes
hematochezia and/
or diarrhoea present;
particularly common in
cockatoos
Clinical signs; thorough
history and diagnostic
work-up to identify the
underlying cause
Egg binding
Various causes, including
hypocalcaemia, uterine
torsion, salphingitis,
malformed or too
big eggs, obesity,
generalized illness,
geriatric bird
Lethargy, anorexia,
tenesmus, diarrhoea or
decreased production
of faeces, abdominal
distension,
Abdominal palpation,
radiographs or
ultrasound (especially in
cases of suspected eggrelated peritonitis)
Feather damaging
behaviour
Often multifactorial.
Causes include medical
issues behavioural/
psychogenic problems
and environmentallyrelated causes
Plucking, biting and/or
fraying of the feathers
on areas of the body
that are accessible to
the birds beak; Grey
parrots and cockatoos
predisposed
Thorough history and
physical exam, additional
diagnostic work-up to
rule out medical causes;
behavioural assessment
Giardiasis
Giardia lamblia
Diarrhoea, weight loss
sometimes feather
damaging behaviour;
mainly in cockatiels
Wet mount (fresh faeces),
flotation (zinc sulphate)
Goiter
Iodine deficiency
Regurgitation, crop
stasis, dyspnoea with
stridor; budgerigars
predisposed.
Tentative diagnosis
based on history and
clinical signs; response to
suppletion therapy
Cloacal prolapse
Polyomavirus or
circovirus
Abstracts | European Veterinary Conference Voorjaarsdagen 2014
Gout
Visceral and/or arthritic
form; often resulting
from chronic kidney
failure
Swelling of the joints,
whitish discolouration; in
visceral form often bird
found dead
Arthrocentesis, cytology
(needle-shaped crystals),
plasma uric acid
concentration
Heavy metal poisoning
Íngestion of lead or zinc;
Sources of lead include
curtain weights, glass-inlead, lead-based paint,
fishing lead, toys, etc;
Zinc mainly derived from
galvanized wired cages
(new wire disease)
Gastrointestinal
signs (crop stasis,
regurgitation, diarrhoea
or undigested seeds in
the faeces), neurologic
signs (ataxia, paresis/
paralysis, seizures,
falling from the perch,
weakness), haematuria,
anaemia
History combined
with clinical signs;
radiographs revealing
metal particle in the GI
tract, lead (whole blood)
or zinc (plasma) levels
Helminthiasis
Ascaridia spp.,
occasionally Capillaria
spp.
Diarrhoea, weight
loss; mainly noted in
psittacines that are kept
in an aviary
Wet mount, faecal
flotation
Hypocalcaemia
Birds fed all-seed diet
low in calcium and/or
with Ca/P imbalance;
lack of sunlight (UV-B)
and/or kidney failure
Seizures, tremors,
weakness, falling from
the perch; mainly in Grey
parrots
Clinical signs
are suggestive;
Confirmation: plasma
calcium is required;
Additional parameters:
phosphorus, uric acid,
total protein and
albumen (via protein
electrophoresis)
Hypovitaminosis A
Birds fed an all-seed diet
Clinical signs include
formation of rhinoliths,
metaplasia of the
mucous membranes and
salivary gland, secondary
infections (particularly
aspergillosis), respiratory
signs, blepharitis/
keratitis, egg binding,
poor feather quality
and/or feather
discolourations
Based on history and
clinical signs
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Macrorhabdosis
Macrorhabdus
ornithogaster
Regurgitation, diarrhoea,
undigested seeds in
the faeces, weight loss;
mainly in budgerigars,
cockatiels and lovebirds
and passeriformes
Cytology of faecal
samples, post mortem
examination
Papillomatosis
Psittacine herpesvirus
suggested
Oral cavity: dysphagia,
dyspnoea, Cloaca:
tenesmus, hematochezia,
prolapse;
mainly affects Amazon
parrots and macaws
Clinical signs and
histopathology of
biopsies of the affected
tissue; vinegar may result
in whitish discolouration
of affected tissues
Torticollis, ataxia,
seizures; mainly affects
Neophema spp.
Surviving birds may
develop steatorrhea and
weight loss
Virus isolation or
serologic testing, post
mortem exam
Acute mortality (<48h
after onset of clinical
signs), anorexia, lethargy,
weight loss, vomiting,
crop stasis, diarrhoea,
abdominal distension,
subcutaneous
haemorrhage; mainly
in nestlings of larger
psittacines (<4 months)
PCR (cloacal swab), postmortem examination
Regurgitation, crop
stasis, undigested seeds
in the faeces, weight loss;
neurologic signs (ataxia,
blindness)
Tentative diagnosis
based on clinical signs
and finding of a dilated
proventriculus on
radiographs; serologic
testing and/or PCR for
ABV (cloacal swab) may
aid in the diagnostic
work-up. Confirmation
by histopathologic
examination of crop
biopsies
Paramyxovirus type 3
infection (Draainekziekte)
Polyomavirus infection
Proventricular dilatation
disease (PDD)
Paramyxovirus-3 (PMV-3)
Avian polyomavirus
Presumably caused by an
Avian Bornavirus (ABV)
Abstracts | European Veterinary Conference Voorjaarsdagen 2014
Psittacine beak and
feather disease
Circovirus
Mainly affecting young
birds; acute form in
Grey parrots resulting
in rapid death; in other
parrots chronic form
with progressive feather
loss and development of
abnormal feathers
PCR (whole blood);
histopathology of feather
follicle biopsy; post
mortem examination
with histopathology
identifying liver necrosis
and bursal atrophy.
In young Grey parrots
severe leukopenia is
suggestive
Psittacosis
Chlamydia psittaci Note:
zoonosis!
Lethargy, anorexia,
weight loss, diarrhoea,
conjunctivitis, rhinitis/
sinusitis, dyspnoea,
neurologic signs;
billiverdinuria
PCR conjunctiva/
choana/cloacal swab,
Quick Vue, Stamp, IFT;
serologic testing
Scaly face and leg
Knemidokoptes spp.
Skin hyperplasia and
crustations of the
skin around the beak
and eyes; mainly in
budgerigars
Skin scraping
Teflon intoxication
Polytetrafluoroethylene (PTFE) fumes
from overheating pans;
Other volatile gases
(e.g., carbon monoxide,
cleaning and disinfectant
agents) may give similar
effects
Acute onset of dyspnoea
Polytetrafluoroethylene
(PTFE) fumes from
overheating pans;
Other volatile gases
(e.g., carbon monoxide,
cleaning and disinfectant
agents) may give similar
effects
History; post-mortem
reveals hemorrhagic
pneumonia
Table 1. Common diseases in psittacine birds including their aetiology, presenting signs, diagnostic work-up and
therapy.
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Disease
Aetiology
Presenting signs
Diagnostic work-up
Atoxoplasmosis
Isospora serini
Lethargy, anorexia,
diarrhoea,
hepatomegaly,
neurologic signs,
mortality (up to 80%);
mainly affecting canaries
<1 year
Post mortem
examination, cytology/
histopathology with
coccidial organisms
found in the
macrophages and other
mononuclear cells
Campylobacteriosis
Campylobacter jejuni
Yellowish diarrhoea,
weight loss; mainly in
nestling tropical finches
< 6 weeks of age
Faecal examination,
difficult to culture
but characteristic
morphology upon
cytological examination
of faecal sample
Canarypox
Poxvirus, transmitted via
biting insects
Cutaneous, diphteric
and septicaemic form,
mainly causing mortality
in canaries
Clinical signs,
histopathology with
characteristic Bollinger
bodies
Candidiasis
Candida albicans, often
in immunocompromised
birds
Anorexia, regurgitation,
crop stasis, diarrhoea
Budding yeast in
cytology of faecal sample
or crop swab
Coccidiosis
Eimeria or Isospora spp.
Diarrhoea, weight loss,
death
Wet mount of faecal
flotation
Cochlosomosis
Cochlosoma spp
Diarrhoea, undigested
seeds in the faeces,
weight loss, death;
predominantly in
nestling finches 10 days
– 6 weeks old (Gouldian
finches, fostered by
Bengalese finches)
Wet mount of fresh,
body-warm faeces
Feather and quill mites:
restlessness, itch, poor
feather quality;
Blood sucking mites:
restlessness, anaemia,
death, predominantly in
nestling birds
Feather and quill mites:
microscopic examination
of feathers;
Blood sucking mites:
visual inspection of the
enclosure (crevices and
cracks; red blood mite)
or birds (Northern fowl
mite) ;
Ectoparasites
Feather and quill
mites (Mallophaga,
Syringophyllus),
Dermanyssus gallineae
(blood sucking mite),
Ornithonyssus sylviarum
(Northern fowl mite)
Abstracts | European Veterinary Conference Voorjaarsdagen 2014
Feather follicle cyst
Genetic predisposition,
mainly in soft-feathered
canaries (Gloucester,
Norwich)
Large, yellow mass filled
with keratinaceous
material; particularly
common on the wing tip
Diagnosis based on
clinical signs
Helminthiasis
Ascaridia spp., Capillaria
spp. most common
(Syngamus spp. in
mynahs and crows)
Diarrhoea, weight loss
(Dyspnoea in case of
Syngamus infection)
Faecal examination (wet
mount, flotation), post
mortem exam
Iron storage disease
(hemochromatosis)
Diets high in iron and/or
rich in vitamin C; mainly
in frugivorous species
(e.g. mynahs, hornbills,
toucans)
Lethargy, weight loss,
abdominal distension,
hepatomegaly, ascites,
dyspnoea
History and clinical
signs; definite diagnosis
requires liver biopsy
Mycoplasmosis
Mycoplasma
gallisepticum
Uni- or bilateral
conjunctivitis, serous
to mucous eye and
nasal discharge,
predominantly in finches
Clinical signs, PCR,
difficult to culture
Pseudotuberculosis
Yersinia
Pseudotuberculosis, mainly
in winter period
(transmitted via rodents
and wild birds)
Acute form with high
mortality, chronic form
with lethargy, decreased
food intake, diarrhoea
and wasting, hepatoand splenomegaly
Post mortem, culture and
sensitivity
Salmonellosis
Salmonella spp.
Clinical presentation
similar to pseudotuberculosis
Post mortem, culture and
sensitivity
Sweating disease
E. coli, Enterococcus spp.
Diarrhoea, weight loss,
death, mainly in young
nestlings
Faecal exam, culture and
sensitivity
Tracheal mites
Sternostoma
tracheocolum
Dyspnoea, clicking
sounds
Transillumination of the
trachea, endoscopy
Table 2. Common diseases in passeriformes including their aetiology, presentings, diagnostic work-up and
therapy.
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