Congenital Abnormalities in Waterfowl and Cranes

Summary Information
Diseases / List of Miscellaneous / Metabolic / Multifactorial Diseases / Disease summary
Alternative Names Congenital malformation.

See also:

Disease Agents Include:
  • Genetic factors
  • Temperature extremes
  • Irradiation (X-rays)
  • Natural plant alkaloids
  • Excessive selenium
  • Various chemical toxins, including formaldehyde, organophosphates such as parathion and diazinon and herbicides such as trifluralin and paraquat)
  • Specific nutrient imbalances:
  • Vitamin A deficiency
  • Excess vitamin A
  • Vitamin B12 deficiency
  • Folic acid deficiency
  • Zinc deficiency)

(J2.20.w2, J7.14.w5, J7.15.w8, B12.5.w10, B119.w1).

Infectious Agent(s) --
Non-infectious Agent(s)
Physical Agent(s)
General Description

Abnormal development of downies during incubation - present at hatching. Presents a variety of syndromes:

  • Limb deformities including duplication of hind toes, enlarged middle toe with terminal phalanges and nail duplicated, toes abnormally positioned and of abnormal proportions in mallards Anas platyrhynchos (J7.14.w5, J7.17.w2).
  • Unilateral or bilateral premaxillary deformities, with grossly narrowed premaxillary area (exaggerated 'spoonbill' shape) in cinnamon teal Anas cyanoptera, southern pochard Aythya erythrophthalma, greater snow goose Anser caerulescens atlanticus (J3.74.w1).
  • Shortening of upper (maxillary) bill in mallard Anas platyrhynchos; also in mute swan Cygnus olor (J3.74.w1).
  • Acrania (absence of frontal and parietal bones and associated meninges, brain herniated outside skull), plus shortened upper bill in mallard Anas platyrhynchos and chiloe wigeon Anas sibilatrix (J3.74.w1).
  • Encephalocoele/meningocoele: domed frontal and occipital area, normal meninges with overlying squamous epithelium lacking in down , but no bone over dorsum of brain in a mandarin Aix galericulata (J2.20.w2); similar condition plus shortened upper bill in mallard Anas platyrhynchos (J3.74.w1).
  • Intraventricular septal defect in a mandarin Aix galericulata (J2.20.w2).
  • Twins sharing a yolk (which neither could absorb), muscovy Cairina moschata (J7.17.w2).
  • Vertebral abnormalities including missing vertebrae, spina bifida and scoliosis, sometimes with associated body and limb deformities, in mule ducks (white Pekin x Muscovy); scoliosis was common in the white Pekin ducks Anas platyrhynchos domesticus from which these ducklings were bred (J5.12.w3).
  • Cervical vertebrae abnormalities resulting in torticollis and/or incoordination. N.B. may survive and live normally, although euthenasia may be required if severely affected (B11.38.w6).
  • Severe twisting and deformity of legs, trumpeter swan Cygnus buccinator (J7.S1.w4)
  • Imperforate vent, trumpeter swan Cygnus buccinator (J7.S1.w4).
  • Possibly congenital cataract noted in a one-week-old Carolina (wood duck) duckling (J6.6.w3).
  • Hydroencephalocele in mallard duckling from a female with Vitamin B12 deficiency (Vitamin B12 Deficiency) (B16.19.w1).
  • Foot malformation in mallard Anas platyrhynchos embryo, due to selenium toxicity (B12.5.w10).
  • Anencephaly and oedema in mallard Anas platyrhynchos embryo following herbicide application to the eggshell (B12.5.w10).
  • Shortened axial skeleton, cervical lordosis, subcutaneous oedema, in mallard Anas platyrhynchos duck embryo following application of low-level organophosphate insecticide to eggshell (experimental) (B12.5.w10).
  • Rachischisis and encephalitis in mallard Anas platyrhynchos duck embryo following exposure to crude oil (experimental (B12.5.w10).
  • Congenital hypoplastic heart valves was considered to be the primary cause of death in one downy chick out of 135 Grus canadensis - Sandhill cranes at Patuxent Wildlife Research Center, 1966-1975. The chick had passive congestion and a markedly enlarged heart (P87.1.w2)
  • A Grus paradisea - Blue crane had a short neck due to the presence of several fused vertebrae; it lived for five years before fracturing the neck. (P76.1989.w2)
  • Doubled nails was seen on the hallux of both feet of one juvenile female out of 1,331 free-living Grus canadensis - Sandhill cranes caught and examined 1974-1999 in Florida, USA, including 365 recaptured individuals. [2005](P87.9.w4)
  • Scoliosis
    • A Grus americana - Whooping crane hatched with a twisted neck (also nervous signs presumed to be related to cerebral oedema). (P87.3.w5)
    • In Grus americana - Whooping cranes at Patuxent Wildlife Research Center, 1982-1995, scoliosis resulted in the deaths of nine chicks (9% of total whooping crane mortality for this period), with four of these dying during hatching. (P87.7.w8)
    • A crane with a deformed neck was first captured as a juvenile in March 1990 and was seen several times over the next two years; it was able to migrate, but was never seen to be paired. This was the only such deformity noted in 1,331 free-living (Grus canadensis - Sandhill cranes) caught and examined 1974-1999 in Florida, USA, including 365 recaptured individuals. [2005](P87.9.w2)
    • Neck malformation (scoliosis) was present in one Florida sandhill crane and one Greater sandhill crane (Grus canadensis - Sandhill cranes), 1990-1991, both yearlings; malformed feathers were also noted in one of the cranes and flaky skin in the other. (B702.19.w19)
Further Information
  • Most non-experimental cases of congenital abnormality have involved a single malformed individual in an otherwise normal clutch. An exception is the finding of varying foot deformities in four of eleven mallard ducklings in one brood.
  • Genetic factors and toxins in the environment have been suggested as possible causes.

(J3.74.w1, J7.14.w5, J7.15.w8, J7.17.w2)

Techniques linked to this disease
WaterfowlINDEXDisInvTrCntr.gif (2325 bytes)
Host taxa groups /species Waterfowl

Cranes (Gruidae - Cranes (Family))

Author Dr Debra Bourne MA VetMB PhD MRCVS (V.w5)

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