Tufts OpenCourseware
Search
Author: Florina S. Tseng, D.V.M.
Color Key
Important key words or phrases.
Important concepts or main ideas.

OCW Zoological Medicine 2008
Waterfowl and Raptor Medicine (2008)
F. Tseng, DVM
Cummings School of Veterinary Medicine at Tufts University

1. Learning Objectives and Review

This section pulls together the main diseases and health issues of wild and captive waterfowl and raptors. In addition some specific captive husbandry, management and rehabilitation issues will be introduced. Color coded topics indicate learning objectives that the student should become familiar with. Cases will be presented in class to illustrate these topics.

2. Waterfowl

2.1. Waterfowl Taxonomy

Order Anseriformes - Anatidae

Anatinae - true ducks

Tadornini

shelducks

Cairnini

perching ducks [spur-winged geese, muscovy, wood duck]

Anatini

dabblers [mallards, etc.]

Aythyini

pochards & allies [scaup, etc.]

Mergini

eiders, scoters, mergansers, etc.

Oxyurini

stiff-tailed ducks

Meranettini

torrent ducks

Anserinae

Cygnini

swans

Anserini

geese

Dendrocygnini

whistling ducks

2.1.1. Taldorini (Shellducks and allies)

  • Anatomically somewhere between true geese and ducks

  • Long necks and legs

  • Some are sexually dimorphic

  • Old World ducks

2.1.2. Cairnini (perching ducks)

  • Muscovy, mandarins, wood ducks etc.

  • Surface feeders

  • Nest in holes in trees

2.1.3. Anatini (dabblers)

  • Mallards, teal, shovelers, pintails and many others

  • Dabble in shallow water for food

  • Often upend when feeding

2.1.4. Aythyini (pochards and allies)

  • Found worldwide

  • All freshwater, except scaup

  • Bodies are short and rounded

2.1.5. Mergini

  • Mergansers, scoters, goldeneyes

  • Inhabit fresh and seawater

  • Typically hole nesters

  • Eat shellfish and crustaceans

  • Mergansers have pointed beaks with toothlike projections

2.1.6. Somateriini (eiders)

  • Found in open sea and coastal waters

  • Eider down used to line nests

  • Males have conspicuous plumage during breeding season

2.1.7. Oxyurini (stiff tailed ducks)

  • Ruddy ducks

  • Stiff tail used as a rudder

  • Large feet, difficulty walking on land

  • Nest on floating platforms

2.1.8. Merganettini (torrent ducks)

  • Three species

  • Western South America

  • Live in fast flowing rivers

  • Swim and dive in rapids

  • Sexually dimorphic

2.1.9. Cygnini (swans)

  • Mute, trumpeter, tundra, whistling swans

  • Long lived

  • Sexually monomorphic

  • Pair for life

2.1.10. Anserini (geese)

  • Canada, brant, snow geese, others

  • Adapted for living on land

  • Long centrally placed legs

  • Long necks, honking calls

  • Social nature

  • Feed primarily by grazing

  • Good swimmers

2.1.11. Dendrocygnini (whistling ducks)

  • Tropical waterfowl

  • Tree ducks

  • Live and nest in or near trees

  • Longer legs and more upright stance than other groups of ducks

  • Gregarious, pair for life

2.2. Anatomy

Phallus
Phallus

  • Sexing: phallus of males

  • Male ducks have sex specific modifications of the syrinx and trachea

Modified syrinx
Modified syrinx

  • Geese and swans molt once a year, ducks twice a year

  • Post breeding "eclipse" (postnuptial molt) - unable to fly during molt

  • Highly modified and sensitive beak for seeking and processing different food sources

  • Webbed feet: anisodactyl/palmate, 3 digits forward, one in back (often vestigial)

  • Presence of crop variable

  • Large cecae

  • Grit present in large, thick-walled ventriculus, especially in granivores

    • Mechanical digestion takes place in the ventriculus

Beak
Beak

Feet
Feet

2.3. Handling and restraint

  • Chief defenses are beaks, wings, and feet

    • Can pinch with beaks

    • Large geese and swans will use wings to fend off attackers

  • Grasp neck just below head with one hand

  • Place other arm around and under body, hold to handlers body

2.4. Captive management

Duck Pond
Duck Pond

seabirds
seabirds

  • For indoor hospitalization,

    • Provide a dry, warm enclosure with non-slip flooring

    • Keep quiet, dimly lit

    • Try to move outdoors if held longer than 48 hours

    • Provide access to water and padded flooring

    • Feed high quality ground waterfowl pellets, lots of greens, e.g. duckweed

  • Domestic waterfowl

    • Selected for size, growth rate, carcass quality, egg production

    • Not easily stressed

    • House indoors at night

  • Ornamental waterfowl

    • Commonly pinioned or kept in netted pens to prevent escape

    • Need access to stream or pond

    • Easily stressed

  • Water quality very important

    • Flow through vs. filtration systems needed to deal with effluent

    • Routine demudding necessary

    • Reed beds can act as purifiers

    • Sea ducks and diving birds require deep water that is ice-free in winter

    • Dabblers require an expanse of shallow water's edge to be able to swim and get out on land

  • Construction of ponds and natural vegetation

    • Stone or concrete often used, watch for foot problems

    • Vegetation should not be too dense, can lead to crop impactions

    • Certain parasites overwinter on grass so periodic deworming may be necessary

  • Animal density dependent on species compatability

    • Most waterfowl are gregarious

    • Some seabirds, e.g. loons and grebes, don't do well housed together

  • Breeding considerations

    • Success in captivity dependent on health of animals as well as simulating natural habitat in captivity

  • Preventing escapes and predation

    • Fencing works for some species

    • Traps and/or bait boxes may be needed to catch predators

    • Netting for aerial predators, e.g. hawks

Predation
Predation

2.5. General care

2.5.1. Quarantine

  • Start collection with juvenile birds reared on fresh, uncontaminated pasture

  • Physical exams, treat with appropriate anthelmintics, routine bloodwork, serology for M. avium and other infectious diseases

  • Minimum six week quarantine

2.5.2. Pinioning vs. fully enclosed caging

  • Pinioning is amputation of the distal phalanx of one wing (removal of MC3 and 4)

Full wing spread in a duck. In captive settings pinioning can be done to prevent escape. This surgical procedure involves the amputation of the distal phalanx of one wing
Full wing spread in a duck. In captive settings pinioning can be done to prevent escape. This surgical procedure involves the amputation of the distal phalanx of one wing

  • Prevents primary feather development

  • Carried out at 2-3 days of age with minimal problems

  • More difficult and traumatic when older

2.6. Nutrition

Wide diversity of natural food habits

2.6.1. Commercially prepared diets

Waterfowl starter (19-22% protein) for first 2-3 weeks of life

  • Waterfowl grower (12-17% protein) up to 4-6 months of age

  • Waterfowl breeder (17-18% protein) for the period prior to and running throughout laying

  • Waterfowl maintenance (up to 14% protein) for general non-breeding use

  • Game bird, trout, sea duck chow

  • Avoid medicated poultry feed!

  • Supplement with greens, grit, and oyster shell especially in young birds

Diets
Diets

2.6.2. Nutritional diseases

2.6.2.1. Angular limb deformities

  • Perosis or slipped tendon (bandylegs) is a condition characterized by enlargement of the hock, bending deformities of the tarsal bones and medial luxation of the Achilles tendon

  • May attempt to repair surgically

  • Angel wing is caused by the weight of the growing flight feathers placing excess stress on the weak muscles of the carpal joint

  • Attempts to correct angel wing with bandaging are often unsuccessful

  • Seen in rapidly growing young

  • May be due to diet too high in protein, too low in calcium, manganese or Vitamin D

  • Poor flooring substrate contributes to development of perosis

  • Correct by increasing greens, decreasing commercial diet, supplement with calcium and phosphorus, correct caging

2.6.2.2. Thiamin deficiency in fish-eaters

  • From feeding frozen fish without B1 supplementation

  • Defrosting of fish leads to activation of thiaminase

  • Clinical signs are neurologic - ataxia, weakness, opisthotonus

  • Responds well to treatment with up to 20 mg/kg thiamin IM weekly

2.6.2.3. Vitamin E deficiency

  • Young growing ducks fed "old" feed or inappropriate feed

  • Diet with rancid fat, requiring more antioxidant activity, leads to low vitamin E levels

  • May result in encephalomalacia, exudative diathesis, reproductive abnormalities

  • Muscle degeneration, capture myopathy have also been linked with vitamin E deficiency

  • Steatitis has been seen in piscivores fed high fat content fish in captivity and in great blue herons from the wild

Angel wing
Angel wing

Vitamin E
Vitamin E

2.7. Infectious disease transmission

Exchange of disease between wild and domestic populations through:

  • Direct contact

  • Environmental contamination

  • Vectors

2.8. Viral diseases

2.8.1. Duck viral enteritis

(Duck plague, DVE)

This is an acute, herpes virus disease of wild and domestic anseriformes (ducks, geese and swans). Wild ducks are the natural host and often transmit disease to domestic and captive breeds. There is marked variation in the susceptibility and mortality of this disease in wild duck species. Massive outbreaks are sometimes seen in waterfowl with hundreds of birds affected. It is most often seen in nonmigratory waterfowl. Duck plague herpes virus can remain latent in the trigeminal ganglion of carrier animals similar to other herpes virus. Shedding through fecal/oral discharge or active disease is produced during periods of stress. This disease is REPORTABLE.

2.8.1.1. Clinical Signs

  • Acute (sudden death), hemorrhagic disease, massive outbreaks

  • Serous and mucoid occulonasal discharge with diarrhea and occasional CNS signs

  • Anorexia, weakness and ataxia with photophobia and pasted eyelids.

  • The ground where sick birds have rested is often blood-stained.

  • Penile prolapse

2.8.1.2. Diagnosis

  • Hemorrhages in liver, pancreas, intestinal mucosa, lungs and kidneys are the typical gross lesions.

  • Hemorrhage into body cavities may also occur.

  • The esophageal-proventricular junction often shows a localized region of mucosal hemorrhage.

  • Annular bands of hemorrhage are sometimes seen in the small intestine that correspond with the GALT.

  • Crusty plaques are sometimes found on esophageal, cecal and rectal mucosa.

  • Intranuclear, eosinophilic inclusions typical of herpes virus disease can usually be found associated with necrotic foci in the liver and mucosal epithelial cells.

  • Vasculitis is also a common microscopic lesion.

Fowl cholera is an important differential diagnosis to consider in an outbreak of duck plague. A Gram stain of peripheral blood from a bird infected with P. multocida will always show many bipolar, gram negative rods.

2.8.1.3. Differential diagnosis

  • Duck Viral Hepatitis

  • Erysipelas

2.8.1.4. Prevention

MLV vaccine available for domestic ducks. Some birds survive infection and become carriers

2.8.2. Duck viral hepatitis - picornavirus

  • Picorna virus

  • Primarily in Pekin ducklings - rapid onset of 100% mortality

  • Lethargy, CNS signs, death

  • Adult mallards act as transport hosts

  • Muscovy ducks are resistant

  • Vaccination of breeding females may help to limit infection

2.8.3. Goose viral hepatitis

  • Parvovirus

  • Not yet known in US

  • Ataxia, diarrhea, coryza

  • Affects goslings < 30 days of age

  • Diagnosed with virus isolation

  • Vaccinate breeding birds to limit infection

2.8.4. Avian influenza (fowl plague)

  • Orthomyxovirus

  • Domestic turkeys and ducks at risk (H5N1 strain is considered pathogenic)

  • Migratory waterfowl may be the viral source (fecal-oral)

  • Mortality previously considered low in waterfowl but recent events in China (2005) indicate that the virus may have mutated to become virulent in waterfowl species (See more on this in Avian Influenza readings and links and Conservation Medicine Challenges)

  • Conflicts arise between poultry industry and waterbird conservation efforts

2.8.5. Newcastle Disease Virus (NDV) - paramyxovirus 1

Cormorant
Cormorant

  • Has been seen in large outbreaks involving double crested cormorants in the Great Lakes

  • Mostly nestlings and subadults affected

  • Clinical signs include torticollis, ataxia, tremors, paresis, and clenched toes

  • Highly contagious

  • Shed in feces

  • REPORTABLE

2.8.6. Poxvirus

Common Murre with pox
Common Murre with pox

  • Avipoxvirus group

  • Songbirds, gamebirds, marine birds are most susceptible

  • Mosquitoes are common vectors

  • Wartlike nodules on featherless areas of the body (feet, legs, base of the beak, eye margin)

  • Cutaneous form is self-limiting and birds can recover if able to feed

  • Internal form of disease (wet pox) is primarily a problem of domestic fowl

  • Emerging disease - reason unclear

2.8.7. Reticuloendotheliosis

  • Avian type C retrovirus

  • Also known as duck infectious anemia

  • Can cause splenic necrosis

  • Infection with REV renders ducks partially resistant to Plasmodium infection

2.8.8. Adenoviruses

  • Upper respiratory disease with tracheitis

  • Seen in domestic goslings

  • Basophilic intranuclear inclusion bodies seen on cytology of infected tissues

2.9. Bacterial diseases

2.9.1. Avian cholera - Pasteurella multocida

  • Many taxa of birds affected with varying susceptibilities - waterfowl and coots are very sensitive to infection

  • Environmental contamination from diseased birds is the primary source of infection

  • Ingestion most common route of infection

  • CNS, GI signs, acute death, hemorrhagic lesions are frequently seen on necropsy

  • Control with early detection, carcass collection and incineration, habitat management

  • Concerns raised about biological costs due to large numbers of birds that die during outbreaks

  • Four major geographic foci - CA, OR, TX, NE

  • 2004 outbreaks in ruddy ducks in CA and cormorants in South Africa. Read more at Outbreak of avian cholera in cormorants - South Africa (2004). ProMED-mail 20040106.0059. <http://www.promedmail.org>. Accessed December 2008.

2.9.2. Riemerella anatipestifer

  • Infectious serositis, fibrinous air sacculitis, pericarditis seen on necropsy

  • Septicemic disease of young domestic ducklings

  • Also seen in young swans and geese in the wild

  • GI, respiratory, CNS signs

  • Differential diagnosis Salmonella, colisepticemia, Newcastle?

2.9.3. Botulism (limberneck)

Botulism in a gadwall
Botulism in a gadwall

  • Western duck sickness, alkali poisoning

  • Paralytic, often fatal disease

  • C. botulinum toxin, type C in waterfowl, Type E in loons and gulls

  • One of most important diseases of migratory birds

  • Summer/fall incidence when ambient temperatures are high and bodies of water become more alkaline

  • Carcass-maggot cycle

    • Toxin production takes place in decaying animal carcasses

    • Flies deposit eggs on carcasses which are fed upon by maggots

    • Maggots concentrate toxin

    • Toxic maggots are ingested by waterfowl

    • Death leads to additional carcasses for toxin production

  • Toxin affects peripheral nerves

  • Affected animals can sometimes recover with supportive treatment, e.g. aggressive oral fluid therapy. Antitoxin available through the National Wildlife Health Center http://www.nwhc.usgs.gov/

  • ELISA test for type C toxin now available for diagnosis from the National Wildlife Health Center http://www.nwhc.usgs.gov/

  • Management actions include carcass pickup and disposal, monitor and modifying environmental conditions

2.9.4. Avian tuberculosis - Mycobacterium avium

M. avium infection in the liver of a bird
M. avium infection in the liver of a bird

  • Seen in turkeys, raptors more often than in waterfowl

  • Seen in species living near sparrows, starlings (reservoir species), and in scavenger species

  • Transmitted by direct contact with infected birds, ingestion of contaminated feed and water, or contact with contaminated environment

  • Chronic disease leads to general clinical signs of emaciation and weakness and specific signs related to the affected organ system

  • Zoonotic potential in immunocompromised humans

2.10. Fungal diseases

2.10.1. Aspergillosis - Aspergillus fumigatus

Aspergillosis
Aspergillosis

  • Opportunistic organism found in the environment

  • Sensitive species: swans, eider ducks, snow geese, seabirds, etc.

  • Acquired through inhalation of spores from environment, especially in stressful captive situations

  • Brooder pneumonia in chicks

  • Clinical signs include emaciation, dyspnea, voice change, chronic anemia

  • Difficult to diagnose in early stages

    • Antigen and antibody titers may be helpful, high WBC counts often present

    • Changes in protein electrophoresis patterns, galactomannan levels

    • Radiology, laparoscopy

    • Cultures of infected tissues, e.g. trachea, lungs, air sacs

  • Combination antifungal therapy needs to be given over a long period of time

Aspergillus from a Murre
Aspergillus from a Murre

2.10.2. Other - mycotoxins (aflatoxins), algal toxins

2.10.2.1. Aflatoxins

  • Aspergillus flavus or parasiticus

  • Has affected domestic ducklings and other species in the SE and Gulf coast states

  • Clinical signs include depression, blindness, tremors

  • Chronic exposure can lead to long term health problems

2.10.2.2. Fusariotoxins

  • Fusarium sp

  • 2 classes of toxins

    • Metabolites that mimic estrogen

    • Trichothecenes

  • Has affected sandhill cranes feeding in contaminated fields

  • Clinical signs include anorexia, vomiting, GI bleeding

2.11. Parasitic diseases

2.11.1. Hematozoans

Plasmodium
Plasmodium

Hemoproteus
Hemoproteus

Leukocytozoon
Leukocytozoon

The most commonly seen species are:

  • Plasmodium spp.

  • Hemoproteus spp.

  • Leukocytozoon spp.

In low numbers, these may not be pathogenic, but numbers may increase with a primary stressor, leading to clinical disease.

2.11.2. Other protozoans

  • Coccidia

    • Infection of kidneys is common

    • Seen in young birds

  • Cryptosporidium

    • Replicate in GI and respiratory tracts

    • Found in domestic and wild ducks and geese

  • Sarcocystis

    • Rice grainlike macroscopic cysts in muscle

    • Does not cause obvious morbidity or mortality

Coccidian parasites found in waterfowl feces
Coccidian parasites found in waterfowl feces

2.11.3. Ectoparasites

Ectoparasites such as this feather louse (Holomen sp.) are commonly found on wild waterfowl.
Ectoparasites such as this feather louse (Holomen sp.) are commonly found on wild waterfowl.

  • Airsac mites (from fowl)

  • Leeches - external, nasal and oropharynx

  • "Wet feather" from feather shaft mites (Cytodites) or feather lice (Holomen spp.)

  • Myiasis

2.11.4. Trematodes

Trematodes, such as this one seen on fecal floatation, can cause hemorrhagic enteritis and hepatitis in birds.
Trematodes, such as this one seen on fecal floatation, can cause hemorrhagic enteritis and hepatitis in birds.

  • Mollusk intermediate hosts

  • Limited host specificity

  • Can cause hemorrhagic enteritis or hepatic damage/fibrosis

  • Can occur in pancreatic and bile ducts of waterfowl

2.11.5. Cestodes

Cestodes generally produce little known pathology in waterfowl, unless coupled with other debilitating problems.
Cestodes generally produce little known pathology in waterfowl, unless coupled with other debilitating problems.

  • Little known pathology unless coupled with other debilitating conditions

2.11.6. Nematodes

  • Gapeworm

    • Cyathostoma bronchialis

    • Found primarily in young geese

    • Adult worms are located in the trachea

    • Cause inflammatory response leading to dyspnea

  • Proventricular worms

Proventricular worm oocysts.
Proventricular worm oocysts.

  • Echinuris (Acuaria daphnia intermediate host), Tetrameres, Eustrongylides, Porrocaecum

  • Burrow into mucosa and submucosa

  • Can cause obstructions of the proventriculus

  • Gizzard worm – Ventricular worms

ventricular
ventricular

  • Amidostomum anseris and Epimidiostomum

  • Found primarily in geese

  • Can result in erosion of the ventricular lining

2.11.7. Acanthocephalans

Acanthocephalan
Acanthocephalan

  • Thorny headed worms

  • Attach deeply or can penetrate through intestinal wall

  • Invertebrate intermediate host ingested by bird

  • Causes severe granulomatous hemorrhagic enteritis

  • Seen in Eider ducks and scoters that feed on bivalves

2.12. Miscellaneous diseases

2.12.1. Gout

  • Articular or visceral forms

  • Uric acid crystals precipitate in the kidneys

  • Can lead to postrenal obstruction

  • Rapid and severe rise in uric acid levels

  • Precipitation on visceral surfaces, joints

  • Hyperkalemia can lead to cardiac arrest

Visceral gout in a bird
Visceral gout in a bird

2.12.2. Capture myopathy

  • Caused by improper handling or stress that causes overexertion

  • Striated muscle damage

  • Warm temps are a risk factor

  • Light colored muscles on necropsy exam

2.12.3. Frostbite

  • Dry gangrene of extremities

  • Tropical and neotropical species are more susceptible

  • Can develop secondary septicemia or bacterial endocarditis

frostbite
frostbite

2.12.4. Amyloidosis

  • Commonly seen in Anseriformes, gulls and shorebirds

  • Deposition of amyloid A in various organs

  • Degradation product of acute phase, reactive protein

  • Seen with chronic infections

  • Can lead to severe hypoalbuminemia

2.12.5. Environmental contaminants

Grebe
Grebe

  • Petroleum

  • Heavy metals

    • Lead , mercury

    • Arsenic, cadmium, selenium

  • Pesticides

    • Organophosphates, organochlorines etc.

  • PCBs, dioxins

  • External effects of oil on waterfowl

    • Skin, ocular burns

    • Feather contamination leading to loss of waterproofing, loss of buoyancy and the inability to fly

  • Internal effects of oil on waterfowl

    • Gastrointestinal

    • Respiratory

    • Neurologic

    • Hematologic

    • Reproductive

    • Immune system

Washing
washing

Rinsing
Rinsing

2.12.6. Foreign body ingestion and entanglement

  • Fishing gear : lead sinkers, jigs, fish hooks, fishing line

  • Plastic trash: six pack rings, cigarette lighters, balloons

Arrow
Arrow

Fishing line
Fishing line

Gizzard
Gizzard

2.12.7. Trauma

  • Predation

  • Fishing line and hooks

  • Male aggression

  • Hit by vehicles

  • Gunshot

2.12.8. Bumblefoot

Seen in captive situations with improper flooring surfaces or perches

Lesions become infected, usually with Staphylococcus sp.

Correct predisposing factors, use proper antibiotics, debridement of lesions and topical meds

Bumblefoot
Bumblefoot

3. Raptors

3.1. Raptor Taxonomy Order Falconiformes

Order Falconiformes

Cathartidae

New World Vultures incl. Condors

Accipitridae

Accipiters: Goshawk, Cooper's, Sharp-shinned

Buteos: Red-tail, Red-shouldered, Broad-wing

Harriers: Marsh Hawk

Kites

Eagles: Bald eagle, Golden eagle

Old World Vultures

Buzzards

Pandionidae

Osprey

Falconidae

Falcons Kestrel, Merlin, Peregrine Caracaras

  • Generally diurnal

  • Spend most of their time on land

  • Carnivorous

  • Molt annually (gradual molt)

  • Some sexual dimorphism (females generally larger than males)

  • Young are altricial

  • Hooked beak and talons

  • Crop present

  • Generally no grit in thin walled ventriculus

  • Small cecum, no distinct phallus

  • Anisodactyl- three digits forward, one in back

3.1.1. Family Cathartidae (New World vultures)

  • Do not have a grasping foot

  • Small unfeathered head and hooked bill

  • Weak talons because only eating dead prey

  • Regurgitate as a defensive action

  • Acute sense of smell used to find carcasses

3.1.2. Family Accipitridae (Kites, Hawks, Eagles) Accipiters

  • Goshawks, Coopers and sharp shinned hawks

  • Woodland birds

  • Prey on smaller birds

  • Short rounded wings with long tails

  • Highly stressed in captivity

3.1.3. Family Accipitridae - Buteos

  • Red tail, red shouldered, broadwing hawks

  • Soaring hawks with broad tails and rounded wings

  • Feed on small mammal species

3.1.4. Family Accipitridae - Harriers

  • Marsh hawk (aka Northern harrier)

  • Long pointed wings, fly close to ground with wings upraised

  • Long legs

  • Eat small mammals, frogs

  • Hover over wetlands and open fields

3.1.5. Family Accipitridae - Kites

  • Mississippi, swallow tailed, black shouldered, others

  • Eat insects, mice, lizards, frogs

  • Eat and drink while in flight

  • Found in open woodlands and swamps, rangelands

3.1.6. Family Accipitridae - Eagles

  • Bald, Golden eagles

  • Large birds

  • Goldens feed on medium sized mammals, snakes, birds, carrion

  • Balds feed on fish, carcasses

  • Large broad wings

  • Powerful feet, beaks

3.1.7. Family Pandionidae - Osprey

  • Fish eaters

  • Platform nesters near fresh or salt water

  • Hover over water, dive

  • Highly stressed in captivity

  • Subject to fishing line and hook injuries, mercury toxicity

3.1.8. Family Falconidae - Falcons, Caracaras

  • Kestrel, merlin, peregrine, gyrfalcon

  • Long wings, bent back at wrist

  • Catch prey by climbing high and stooping down at high speeds

  • Prone to bumblefoot in captivity

3.2. Raptor Taxonomy Order Strigiformes

Order Strigifiormes

Tytonidae

Barn owls

Strigidae

Great horned owl, Barred owl, Screech owl, Saw-whet owl, Snowy owl

  • Mainly nocturnal

  • Spend much of time on land

  • Carnivorous

  • Molt annually

  • Primary feathers have serrated edges for silent flight

  • Slight sexual dimorphism

  • Young are altricial

  • Hooked beak and claws

  • Triangulate sound to locate prey

  • Crop absent

  • Semi zygodactyl (two toes in front, two in back)

3.2.1. Order Strigiformes Tytonidae

  • Barn owls

  • Roost and nest in dark cavities in old buildings, cliffs, trees

  • Common in west, uncommon in eastern US

3.2.2. Order Strigiformes Strigidae

Great horned, barred, screech, saw whet, snowy, great grey, boreal owls

3.3. Handling and restraint

Bald Eagle
Bald Eagle

  • The weapons - talons and beak

    • Always have these weapons under control at all times

    • Be aware of different species' behavior, e.g. falcons like to bite!

  • Use hood to decrease visual and auditory stress

    • Transport

    • Sturdy boxes or crates

    • Sufficient ventilation, avoid placing boxes so that air circulation is impaired

    • Keep darkened

    • Do not use perch, use tail wraps to protect tips of feathers

    • Cover floor with carpeting

Beak
Beak

Talons
Talons

3.4. Noninfectious diseases

Hyphema
Hyphema

  • Competition pressure among young in the nest or adults in groups in captivity can lead to starvation

  • Trauma - interaction with man-made objects (hit by vehicles, flying into windows or buildings, electrocution, barbed wire entanglement, leg hold traps), ocular trauma in owls

  • Gout

    • Predisposing factors include high dietary levels of protein and calcium, hypervitaminosis D, poor renal function, dehydration, stress

    • Correct diet, decrease Ca, P, Mg, and Vit D3, ensure adequate levels of Vitamins A and B

  • Rickets and Metabolic bone disease are a commonly seen in young raptors that are kept in captivity and fed only skeletal meat. This occurs when bids are not fed whole prey, which includes bone as a source of calcium and phosphorus. Clinical signs of metabolic bone disease involve similar signs seen in poultry including rickets, pathologic fractures, and a soft bills.

Rickets - Metabolic bone disease in a young raptor
Rickets - Metabolic bone disease in a young raptor

3.4.1. Toxicity

3.4.1.1. Lead

Lead poisoning
Lead poisoning

  • Most frequently seen in eagles

  • From ingesting lead in prey

  • Clinical signs include weakness, inability to fly, neurologic signs, emaciation

3.4.1.2. Mercury

  • Exposure occurs through accumulation of mercury in the food chain, agricultural use, point source industrial and mining discharge into the environment

  • Most commonly a problem in piscivores, e.g., osprey, eagles

  • Toxic form is methylmercury

  • Neurologic signs, emaciation

3.4.1.3. Pesticides

Pesticide toxicity
Pesticide toxicity

  • Organophosphates, carbamates

    • Cholinesterase inhibitors

    • Raptors are victims of secondary poisoning through their prey

    • Convulsions, paralysis, miosis, dyspn

    • Birds that die rapidly may be found with vegetation clenched in talons

  • Rodenticides

    • Secondary poisoning in raptors

    • Anticoagulant hydroxycoumarins and indanediones, most commonly brodifacoum

    • Inhibit vitamin K1 activation

    • Clinical signs include pallor and excessive external hemorrhage from superficial wounds

    • Can lead to sublethal effects

    • Treat with vitamin K1 supplementation for 4-6 weeks

3.4.1.4. Asian vulture die-off

  • Precipitous population decline in the 1990 s in Gyps sp. in India >95% of vultures have died

  • Necropsy findings showed birds with severe visceral gout and acute renal failure

  • Diclofenac identified as the toxic agent

    • Human NSAID recently used in Pakistan for pain relief in domestic livestock

    • Vulture feeding on carcasses ingested diclofenac in lethal quantities

    • All vultures with visceral gout had diclofenac in their kidneys

    • Experimental exposure trials conducted

3.5. Infectious diseases

3.5.1. Viral diseases

  • Poxvirus - especially eagles

  • Herpesvirus - Owl herpes, falcon herpes, eagle herpes

    • Transmitted through feeding on infected prey

    • May develop carrier status

    • Depression, sudden mortality

    • Diagnosed through virus isolation, intranuclear IB in liver, spleen, bone marrow

  • Adenovirus - from avian derived food

    • Melena, anemia

    • High mortality in kestrels with hemorrhagic enteritis

    • Two types of intranuclear IB

  • Paramyxovirus

    • Low to moderate susceptibility

    • Have seen anorexia, torticollis, and sudden death in owls

    • May show long term fecal viral shedding

    • Nonpurulent encephalitis

  • West Nile Virus - Raptors moderately susceptible

3.5.2. Bacterial diseases

Bumblefoot
Bumblefoot

  • Bumblefoot/pododermititis

    • Falcons especially susceptible

    • Initial injury, inappropriate perching surfaces

    • Plantar surface of metatarsal pad

    • Staph aureus, others

    • Antibiotics, bandaging, surgery, correct predisposing conditions

  • Avian Tuberculosis

    • Widespread problem in raptors

    • GI form predominant

  • Chlamydiosis - chronic form seen in raptors

3.5.3. Fungal diseases

Asper
Asper

  • Candida - oropharyngeal mucous membranes and esophagus are often affected

  • Aspergillus

    • Common, often fatal

    • Acute and chronic forms

    • Seen as a secondary problem with primary stressor

    • Northern species of raptors more susceptible

3.5.4. Parasitic diseases

3.5.4.1. Protozoa

Trichomoniasis
Trichomoniasis

  • Trichomonas - frounce

    • Flagellated organism in mucosa of oropharynx, esophagus and crop, can be generalized

    • Common in pigeons and doves which are then consumed by raptors

    • Falcons most susceptible

  • Plasmodium

  • Haemoproteus

  • Leukocytozoon

3.5.4.2. Liver/intestinal trematodes

Trematode
Trematode

  • Found in small intestine, liver

  • Diarrhea, weakness

  • Eggs shed intermittently

  • Treat with praziquantel

3.5.4.3. Cestodes

Cestode
Cestode

  • Only rarely cause clinical disease

  • Treat with praziquantel

3.5.4.4. Nematodes

  • Ascarids

  • Capillaria

    • Very common in raptors

    • Found in oropharynx, esophagus, intestinal tract

    • Earthworms play a role in transmission

    • Can become infected by ingestion of infected prey

  • Syngamus

    • Adult worms live in trachea

    • Ingestion of transport hosts (earthworms, snails)

    • Eggs are coughed up and excreted in feces

    • Clinical signs include upper airway obstruction, sneezing, headshaking

  • Seratospiculum

  • Mites, lice, Hippoboscid flies

Syngamus
Syngamus

Capillaria
Capillaria

3.6. Avian Vacuolar Myelinopathy "Coot and Eagle Brain Disease"

  • First described in bald eagles in 1994. Also seen in American coots and ducks.

  • Restricted to the Southeastern US so far.

  • Clinical signs of ataxia, wobbly or uncoordinated flight, swimming in circles

  • Birds often found dead

  • NO gross lesions; histologic examination shows vacuolization and diffuse spongy degeneration of white matter in the central nervous system.

  • Etiology unknown. Toxic exposure is suspected.

4. References and Resources

4.1. Websites

National Wildlife Health Center . 6006 Schroeder Rd., Madison, WI 53711. (608) 271-4640.

4.2. Texts and Articles

4.2.1. Waterfowl references

Altman, Robert B., et al. Avian Medicine and Surgery. Philadelphia. W.B. Saunders Co., 1997. Chapter 55

Bellrose, FC. Ducks, Geese and Swans of North America. Stackpole Press. Harrisburg, PA, 1974.

Best practices for migratory bird care during oil spill response. U.S. Fish and Wildlife Service, November, 2003.

Beynon, Peter H. Manual of Raptors, Pigeons and Waterfowl. BSAVA, 1996.

Cottam, C. Food habits of North American diving Ducks. USDA Technical Bulletin #643, 1939.

Ducks, Geese and Swans of the World. University of Nebraska Press. Lincoln, NE, 1978.

Feierabend, JS and Russell, AB. Lead poisoning in wild waterfowl. National Wildlife Federation, Washington, DC, 1986.

Friend, M. Ed. Field Manual of Wildlife Diseases: General Field Procedures and Diseases of Birds . United States Department of the Interior, United States Geological Survey,1999.

Harrison, Gregg J. and Teresa L. Lightfoot. Clinical Avian Medicine. Palm Beach, FL: Spix Pub., c2006. Chapter 36.

Hyde, DO (ed). Raising wild ducks in captivity. EP Dutton and Company, NY.1974.

Johnsgard, PA. Waterfowl: their biology and natural history. University of Nebraska Press. Lincoln, NE, 1968.

LaBonde, Jerry. Private collections of waterfowl. Proceedings of the Association of Avian Veterinarians, 1996, pp. 215-223.

Larsen, R. Scott, et al. Clinical features of avian vacuolar myelinopathy in American coots. JAVMA, v.221 (1), 2002: 80-85.

Martin, RM. Wildfowl in Captivity. John Gifford Co., London,1973.

Ritchie, Branson W., et al. Avian Medicine: Principles and Application. Lake Worth, Fla., c1994: Chapter 46.

Russell, WC, Choules, DL and Gauthier, DA. Detergents and waterfowl. Journal of Zoo Animal Medicine, 12:10-13, 1981.

Souza, MJ, and LA Degernes. Mortality Due to Aspergillosis in Wild Swans in Northwest Washington State, 2000-02. Journal of Avian Medicine and Surgery, 19 (2), 2005: 98-106.

Wild Waterfowl and its Captive Management, Vols. 1 & 2. American Gabe Breeder's Cooperative Federation. Salt Lake City, Utah, 1974.

Wobeser, GA. Diseases of Wild Waterfowl. 2nd ed. Plenum Press. NY. 1997.

4.2.2. Raptor references

Altman, Robert B., et al. Avian Medicine and Surgery. Philadelphia. W.B. Saunders Co., 1997. Chapter 52

Beynon, Peter H. Manual of Raptors, Pigeons and Waterfowl. BSAVA, 1996.

Harrison, Gregg J. and Teresa L. Lightfoot. Clinical Avian Medicine. Palm Beach, FL: Spix Pub., c2006. Chapter 40.

Heidenreich, Manfred. Birds of prey. Blackwell Science, 1997.

Redig, P.T. et al. 1994. Raptor biomedicine. Univ. of Minnesota Press, c1993.

Rodriguez R, et al. The Normal Electrocardiogram of the Unanesthetized Peregrine Falcon (Falco peregrinus brookei). Avian Diseases, 48 (2), 2004: 405-409.

Wobeser, G, et al. Secondary poisoning of eagles following intentional poisoning of coyotes with anticholinesterase pesticides in Western Canada. Journal of Wildlife Diseases, 40, 2004: 162-172.

W√ľnschmann, Arno, et al. Pathologic Findings in Red-Tailed Hawks (Buteo jamaicensis) and Cooper's Hawks (Accipiter cooperi) Naturally Infected with West Nile Virus. Avian Diseases: Vol. 48 (3): 570-580.