Guidelines important in evaluating cytological samples for birds - DVM
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Guidelines important in evaluating cytological samples for birds


DVM360 MAGAZINE


Normal cytology of the oral cavity, esophagus and crop of psittacines can include moderate numbers of Gram-positive bacteria and few to rare Gram-negative bacteria. Candida spp are not commonly present in large numbers except when an infection is present. However, moderate numbers of non-budding yeasts are indicative of a dietary source rather than an active infection. The presence of fungal hyphae indicates a severe fungal infection with possible tissue invasion.

Crop washes are performed by infusing a small amount of saline into the esophagus/ingluvies using a soft plastic or rubber feeding tube, gently massaging the crop and its contents, and aspirating the fluid. The sample may be concentrated by centrifuging the collected material and examining smears of the "pellet."

Cloacal/fecal cytology is often used as a routine part of the physical exam of avian patients. A saline-moistened cotton-tipped swab of appropriate size is gently inserted into the cloaca to obtain a sample. For fecal cytology, fresh is best.

Normal cloacal cytology usually reveals a low to moderate number of squamous cells with varying degrees of keratinization and centrally or eccentrically located vesicular nucleus as well as gram-positive bacteria, an occasional gram-negative or Candida-like yeast and urate crystals The normal fecal bacterial flora of psittacines consists predominately of Lactobacillus spp, Bacillus sp, as well as Staphylococcus and Streptococcus spp. Abnormal samples may contain large numbers of Gram-negative bacteria, many Candida-like yeasts organisms (especially budding ones) and protozoa or parasitic ova. Protozoal organisms, such as Trichomonas sp. or Giardia sp. can be identified using stains specific for those organisms.

Cytology of the respiratory tract

  • Infraorbital sinus aspirate/flush: Sinusitis of the nasal and infraorbital sinuses is a condition that often affects psittacine birds. Several methods (with or without anesthesia) may be used to obtain aspirate from the infraorbital sinuses; however, a thorough knowledge of the anatomy of the sinus and surrounding structures is necessary in order to perform these procedures correctly. The first involves restraining the birds head and body and inserting a 20-25 gauge needle (with syringe) at the commissure of the mouth and directed vertically to a point midway between the eye and nares passing under the zygomatic bone. The sinus may be aspirated, or a small amount of sterile saline may be infused into the sinus and then aspirated. The second method involves approaching the sinus at a perpendicular angle and entering the sinus directly. A third method requires entering the sinus from a rostral direction by inserting the needle just caudal to the commissure of the mouth. The needle is directed ventral to the zygomatic arch, ending in the sinus under the eye. Normal cytology of the infraorbital sinus is poorly cellular with little background debris.
  • Tracheal wash: In order to properly perform a tracheal wash, the patient should be anesthetized or appropriately restrained; 1-2 ml/kg of sterile saline is infused into the trachea as close to the syrinx as possible and then quickly aspirated. Tracheal aspirations are indicated in patients with clinical signs of a tracheobronchitis (e.g. persistent cough), radiographic evidence of respiratory disease, other evidence of tracheobronchial disease or a lesion involving the syrinx. Normal tracheal cytology is similar to that of the sinuses.
  • Air-sac wash: Lower respiratory tract diseases may be diagnosed with the aid of air-sac washes. A small amount of saline (1-3 ml depending upon the size of the patient) may be infused into the appropriate abdominal air sac based upon radiographic evaluation. The caudal abdominal air sac is approached through an aseptically prepared area caudal to the last rib. A small-gauge needle with syringe attached inserted into the air sac, sterile saline is infused and then aspirated. The air-sac wash is accomplished easily with the aid of endoscopy.

Abdominocentesis Indications for abdominocentesis include ascites, peritonitis, hemoperitoneum or other coelomic cavity fluid accumulation. Abdominocentesis is performed by aseptically preparing a small area on ventral midline caudal to the point of the sternum. A small-gauge needle or butterfly catheter is inserted on ventral midline and directed toward the right side of the coelomic cavity thereby avoiding trauma to the ventriculus and other organs. Any fluid present is aspirated into a sterile syringe. Lavage of the coelomic cavity is performed similarly. Normal abdominal fluid is poorly cellular with an occasional mesothelial cell or macrophage.


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Source: DVM360 MAGAZINE,
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