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A young Sulfur-crested cockatoo was recently purchased from a breeder with a PBFD-free closed aviary, and shipped by airplane to its new owner, who owns no other birds. The owner had saved up her money to purchase this one special bird as a pet. Being an informed and conscientious bird owner, she brings the bird into your office for a complete work-up and exam one week after its arrival at its new home. The bird looks perfectly normal on physical examination, and it has completely normal feathers. Its weight is perfect for its size and it is bright, active and playful. The white blood cell count is, however, somewhat depressed (WBC 4,500, 58% heterophils, 42% lymphocytes). You are surprised when the PBFD DNA PCR probe test comes back positive (taken by clean venipuncture). What should you tell the owner?
A positive PBFD test in a young bird with no feather abnormalities suggests that it has been recently exposed to the PBFD virus and is viremic, or that it is latently infected. The best advice that you can give the owner is not to panic, as there is a good chance that the bird will be able to eliminate the virus on its own. If the bird was not shipped in a biosecure container, it may have been exposed en route in the cargo hold of the aircraft, as the virus may be able to remain in the environment for quite some time, if it acts like another circovirus, CAV. If other birds, including PBFD positive birds, were shipped in the same cargo hold, exposure would be likely.
Blood for PBFD testing should be taken by clean venipuncture, and not by a toenail clip, as virus particles may contaminate a blood sample resulting in a false-positive result. If a positive result is obtained from a toenail clip, the test should be repeated, using venipuncture.
Many young birds exposed to PBFD will be transiently positive and will eliminate the virus. These birds will only develop disease if the immune system is unable to clear the infection. However, if a young bird is PBFD positive and has feather abnormalities, then that suggests that the bird has an active PBFD infection. A PBFD positive young bird with no feather abnormalities should be retested in 90 days. If the bird is still positive, then it should be considered to be latently infected or that it is being continuously exposed to the virus. A negative test 90 days later would indicate that the viral nucleic acid is no longer detectable in the blood, and that the bird has eliminated the virus.
So the news is good for the owner of this cockatoo. The odds are that this bird will be able to mount an effective immune response to this virus and will test negative in 90 days at the retest.
Ritchie BW. Circoviridae In: Avian viruses: function and control. Lake Worth, Florida, USA: Wingers Publishing, 1995:243-247.
A young weaning Blue and Gold macaw, Ara ararauna, is presented by the upset breeder. She had been keeping a dish of seed, including whole, unshelled peanuts, in the weaning cage. She had noticed that the entire peanuts were gone from the cage, shells and all. When she picked up the macaw, she could feel the whole peanuts in the crop, and could hear them rattling in the shells. What should you do?
Many objects, if contained in the crop, can be manually manipulated up the esophagus and into the oropharynx. The foreign body can then be retrieved with a curved hemostat. In most cases, ingluviotomy can be avoided. Most hand-feeding, weaning baby parrots can have foreign bodies successfully removed from the crop without anesthesia or surgical intervention. To manipulate a foreign body up and out, the crop should be almost empty of hand-feeding formula, so that the FB can be easily palpated. The FB can be easily slipped up the esophagus, with the vet taking care to not damage the ingluvial lining by handling the crop roughly. Once the FB is visible in the oropharynx, a second person can use a curved hemostat to grasp the FB and remove it from the bird. In this case, five whole peanuts, shells and all, were manually retrieved from the crop of this bird. In rare cases, small FBs, such as jewelry items, an ingluviotomy may be required. Under isoflurane anesthesia, with supplemental heat, a small incision is made in the skin over the ingluvies in an avascular area. The crop lining will then be visible. An incision is then made into the crop, and the FB can be retrieved. If necessary, sterile warmed saline solution can be flushed into the crop to clear out hand-feeding formula, for better visibility. Before flushing, it is best to plug the esophageal opening with a gauze square to prevent reflux into the oropharynx, and resultant aspiration. The incision should be closed in two layers. The crop lining should be closed with 4-0 absorbable suture, in a simple continuous pattern. Then a Cushing's oversew should be performed. The skin can be closed with 3-0 or 4-0 non-absorbable, monofilament, in a Ford's interlocking pattern. If a soft feeding tube is lost in the crop, and it migrates through the esophagus and thoracic inlet into the proventriculus, the tube may be retrieved using an endoscope and graspers, either attached to the endoscope or by the use of an alligator forceps, through an incision made into the crop. Endoscopic equipment is not very helpful in cases of large foreign body in the crop, and manual manipulation is a better method. Most foreign bodies can be successfully removed from the crop without surgical intervention. In this case, the five peanuts were manually retrieved and the bird was able to go home with the relieved owner, with no follow-up care necessary, since surgery was avoided. The owner was instructed to chop all food items into bite sized pieces, and to avoid giving weaning birds whole food objects, such as peanuts. (As a side note, owners may call for advice after a macaw ingests whole grapes. Grapes can be palpated in the crop, if eaten whole. Advise the owner to gently squeeze the grapes in the crop, and in the future, cut the grapes into small pieces to prevent this from occurring again.) Smith KA. Pediatric management techniques: a veterinarian's viewpoint. Manual of Avicultural Management and Medicine, Assoc Avian Vet, 1993: P2-8. Bennett RA, Harrison GL. Soft Tissue Surgery. In: Ritchie BW, Harrison GJ, Harison LR (eds). Avian medicine: Principles and Application. Lake Worth, Florida USA: Wingers Publishing, 1994: 1115-1117.References:
Copyright © 2006 Margaret A. Wissman, D.V.M., D.A.B.V.P.
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