Practical Lab Session - Avian Practical Lab
Teresa L. Lightfoot D.V.M., Diplomate ABVP - Avian
Welcome, and get ready for the crash course in basic avian medicine. This doesn't necessarily mean that you are a beginner - I think we all learn from going over the "basics". We may learn some new facts or a different approach to certain presentations. In any case, whether you are here as a beginner, intermediate or someone who has a lot of experience and ideas to share - let's enjoy this time and get as much practical experience and information as possible from this lab.
Brief case histories are provided with the radiographs. Note normal and abnormal findings for each, and see if a significant diagnostic interpretation can be made with the history and radiographs. Jot down notes so that we can discuss these cases.
Also please use these to assess your familiarity with normal radiographic anatomy.
With the budgies provided, venipuncture will be done on the right (the larger) and left jugular veins. The wing vein (basilic vein, also referred to as the brachial, or ulnar vein) and metatarsal vein will also be visualized, but not utilized in order to minimize trauma to the birds. The wing vein tends to be uncomfortable, leave a large hematoma, and in birds with calcium deficiency, fractures of the wing may occur due to excessive restraint. A method of venipuncture at this site that involves going in under the tendon and approaching the vein from behind (the dorsal aspect) will be demonstrated. This avoids hematoma formation in most cases. The metatarsal vein in psittacines is quite short, and difficult to isolate in birds under 300 - 400 grams. Also, although hematomas are uncommon due to the lack of a metatarsal subcutaneous space, bleeding from the venipuncture site is common and often when utilized this vein necessitates a pressure wrap post venipuncture. Toe nail trims are generally not used, due to the inaccuracy of samples taken from this site if the blood is not free-flowing. There is also discomfort to the bird and danger of septicemia if the toenail cut is high enough to allow free flowing blood. You may elect to do the one or two person technique for venipuncture - both will be demonstrated.
In practice, the bird would be examined at rest - either in the cage, on the owner, or on your hand, noting any signs of illness such as fluffed feathers, tail bob, open mouth breathing, partially closed eyes, sleepiness, weak grip, etc. Once restrained and throughout the examination (both here, and in practice) the bird should be constantly re-assessed to determine if it is tolerating the restraint. (Please see the "Put It Down" list in the Hospital Precautions lecture).
Head: Looking straight at the bird, the eyes should be examined for symmetry of size of the globes, evidence of cataracts, proper pupilary constriction, etc. The cere above the nares should be examined for any matting of feathers or discharge.
Nares - size, symmetry,nd presence of material within the nare should be noted. Placing a drop of saline in the nare can help to determine whether the material in the nare is merely debris that has accumulated on the operculum or occlusion of the nare, by observing for it to "disappear " as the bird inhales. If this is repeated in both nares and the choana is also patent one should see the bird's tongue move, as it tastes the saline enter its mouth.
Oral cavity - These small birds are difficult to examine thoroughly while awake due to the small size of the oral cavity. At a minimum, the color of the oral mucosa should be noted, checking for anemia or hyperemia. The base of the tongue, a favorite place for irritant materials to manifest hyperemia, should be examined. Also at the base of the tongue, cockatiels in particular are prone to "sterile " abscesses from squamous metaplasia following Vitamin A deficiency. These are usually bilateral, whitish to yellow lesions that appear on either side of, and slightly rostral to, the glottis.
The choanal papilla should also be examined. The blunting or absence of papilla indicate Vitamin A deficiency, previous infection, or both.
Locate the ingluvia by palpation. There should normally be at least some food material in the crop. Wet the area lightly with alcohol to observe the thin layer of skin and subcutis over the crop, and visualize the material inside.
Feathers: Much useful information concerning a bird's general health and nutritional status, both present and past, can be gotten from examination of the feathers. Lack of elasticity is often the result of nutritional deficiencies, and poor collagen deposition in the supportive tissues. Stress bars may indicate previous illness, or nutritional deprivation. Poor interlocking of the barbules, resulting in "unzipped" feathers may be nutritional or mechanical self-trauma. Obvious self-mutilation of the feathers may occur due to many reasons.
Breast muscle: Note the presence of an area of apteria along the carina of the keel. This is normal in most psittacines. Note the relative body musculature of the bird. Obesity, "soft" muscling, recent weight loss, and/or emaciation may be detected. Palpate the abdomen, and determine if the sterno-pubic distance is normal. Extend each wing and check for missing feathers, areas of dermatitis, new feather growth, and ant musculoskeletal abnormalities.
Legs: As noted in the "Put it Down" list found in the Hospital Precautions lecture, evaluate the strength and symmetry of the bird's grip.
Cloaca: We will be collecting swabs for submission for Polyoma testing. While collecting these cloacal swabs, evert the cloaca and note the thickness and texture of the cloacal mucosa. Although the species provided are not prone to cloacal papillomas, this should be part of the P.E. of all birds.
We will administer 1.0 ml over the back of each bird - once per person (so, twice per bird). The precautions here, besides the bird's basic stability and ability to tolerate the restraint, is to be certain that the needle is subcutaneous, not IM, IL (intra-lung) or IK (intra-kidney). Besides visualizing the needle as you begin the administration, you should also notice an immediate bleb. If any resistance is encountered, it is likely that you are against a rib, and it is advisable to retract your needle slightly. Be aware of the bird's respiration throughout this procedure. Subcutaneous fluid with hyaluronidase (WydaseR) either lyophilized or stabilized - the 150 units/ml - add 1.0 ml to each bag of fluid for subcutaneous use to aid in absorption. It can be ordered through Burns, Butler, & other companies. Wydase has been used for years in dog and cat medicine but fell by the wayside with the advent of I.V. catheters. It is tremendously useful in birds & other exotics (Currently on manufacturers backorder but can be obtained through most compounding pharmacies). Maintenance fluid dosage is approximately 3.0 ml/100 grams B - QID.
For safety reasons, we will gavage feed with sterile saline, and only use 0.3 ml/bird. You may elect to do this alone or with a partner holding the bird; whichever is most comfortable. Be aware of the location of the crop to the right of the body, making introduction of the gavage feeder on the left side, directed toward the right, the easiest method of feeding. Visualize the feeder through the crop, and palpate both the crop feeder and the trachea separately. Be careful not to occlude the trachea with the body of the feeder while performing this portion of the lab.
In practice, do not initiate crop feeding unless the bird has been rehydrated, and is sufficiently stable to stand and ambulate in order to avoid aspiration of the crop feeding contents. Generally in adult birds, 3 ml/100 grams, QID of a hand feeding formula (HBD and Exact are two favorites) will maintain weight, when accompanied by subcutaneous fluids in an anorexic bird. After the technique has been mastered, it is often easier for one person to do this alone, especially on smaller birds (up through about 400 grams, or Amazon size) using your thumb to not only feel the crop feeder pass through the esophagus (separate from the trachea, which is cranial to your thumb), but also using the thumb to occlude the esophagus, preventing back-flow of any material from the crop into the pharynx. Hand-feeding baby birds can usually receive up to 10% of their body weight at each feeding - the number of feedings depending on age. (So a healthy four week old cockatiel, which may weigh 100 grams, would be getting up to 10 ml/feeding, three to four times/day, whereas a sick adult cockatiel of the same weight could only take about 3 ml - 3 times daily).
Although this lab is not sufficiently long to provide a good course in avian hematology, there will hopefully be a microscopes and slides demonstrating the primary avian blood cells, and the formula for doing both an estimated and an Eosinophil pipette based CBC. Although the CBC, in my opinion, is more accurate with the Eosin pipette, many practitioners and technicians have developed sufficient consistency in slide preparation to make the estimated WBC a useful tool. It is certainly better than no CBC at all, especially on occasions where all one can get from a bird is one or two drops of blood. It is surprising that a sick budgie or cockatiel will often mount a tremendous WBC response - from a normal of 3500 - 8500, up to 15,000 - 25,000, in the presence of infection. So don't hesitate to utilize this method if the Eosin Unopette is not suitable for your practice at this time.
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