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Authors: Gretchen Kaufman, DVM, Maureen Murray, D.V.M.
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OCW Zoological Medicine 2008
Avian Diagnostic and Therapeutic Techniques (2008)
G. Kaufman, DVM / M. Murray, DVM
Cummings School of Veterinary Medicine at Tufts University

1. Learning Objectives

Be familiar with the diagnostic and therapeutic options available in avian medicine. Color coded topics indicate learning objectives that the student should become familiar with.

2. Pet Bird or "Individual Bird" Diagnostic and Therapeutic Techniques

The techniques described below are common practice in pet bird medicine. These techniques are not restricted to psittacines however and can be employed in any individual bird situation (including wild birds and chickens). Techniques commonly used for poultry or "flock" medicine are described at the end of this chapter.

2.1. History taking

A complete and thorough history is absolutely essential in avian medicine as it is in small animal practice. Many of the diseases seen are a direct result of husbandry or management practices in the home , or due to exposure to other birds. The history should include the following information at a minimum:

  • Signalment: species, age, sex (?)

  • Acquired when and where from: Pet store, breeder, friend, etc.

  • Husbandry questions

  • Dietary history

  • Exposure to other birds

  • Details of illness

See examples of special client questionnaires in the Supplementary Material folder.

2.2. Physical examination

Physical examination

The physical examination should be routine and comprehensive as in all other animals. This includes obtaining an accurate body weight in grams. The examination is usually performed in two parts:

Physical exam
Physical exam

  • Part I: observe the bird in the cage or carrier - evaluate respiration, posture, droppings

  • Part II: hands on examination from head to toe, including a thorough oral exam

Sometimes the physical examination can be very stressful for the bird. It is important to keep an eye on respiratory rate, body temperature and attitude as signs of stress . The bird may need "rest periods" if very stressed, requiring the physical examination to be performed in stages.

2.3. Routine Diagnostic Tests

2.3.1. Fecal examination

A fecal examination for parasites is important, especially in the new bird. Both a direct smear (saline) and flotation should be performed to look for protozoal and helminthic parasites. A gram stain of a fecal smear is also sometimes performed to look for abnormal bacterial flora when indicated.

Normal fecal gram stain from psittacine
Normal fecal gram stain from psittacine

2.3.2. Routine culture techniques

Bacterial diseases are very commonly encountered in pet bird medicine. Cultures and antibiotic sensitivity testing are therefore vital in correctly diagnosing and treating these conditions. Cultures in these small creatures necessarily require the use of mini-tip culture swabs which should always be on hand in an avian clinic. The following cultures are routine, while more invasive cultures can also be performed as indicated:

  • Respiratory tract - choanal culture

  • GI tract - cloacal culture

  • Folliculitis - feather follicle culture

    Choana
    Choana

    Cloaca
    Cloaca

2.3.3. Routine blood work

2.3.3.1. Sample collection

The most commonly used sites for blood collection in birds include:

  • the jugular veins

  • cutaneous ulnar veins

  • tibiotarsal/metatarsal veins

Volumes needed rarely exceed 1 ml, and should not exceed 1% of the animal's body weight in grams.

Phlebotomy
Phlebotomy

Collection of such small volumes require the use of small needles (25g, 26g, 27g), and small receptacles (e.g. Microtainers, hematocrit tubes, unopettes). Avian blood clots very quickly and should be collected and transferred to the appropriate receptacle as quickly as possible.

Microtainers
Microtainers

2.3.3.2. Complete blood count

Avian CBCs are often performed in-house, but may be sent out to a diagnostic laboratory. To perform a CBC, you will need at least one smear (differential), one unopette (WBC count), and one hematocrit tube(PCV, TSP). Ideally a full CBC is performed on 0.2 ml EDTA blood (Microtainer).

Avian RBC's are big and nucleated!

Avian blood smear
Avian blood smear

WBC counts are accomplished using eosinophil unopettes. The unopette comes with its own pipette and a fixed volume of diluting fluid, which allows for an accurate dilution of the blood sample. One disadvantage is that the phloxine diluent stains only granulocytes (heterophils, eosinophils, and basophils); therefore, the count obtained must be corrected, since mononuclear cells (lymphocytes and monocytes) are not included. A hemacytometer is used to produce the granulocyte count. A white blood cell differential count must then be done to accurately complete the WBC count:

TOTAL WBC/ul EQUALS hemacytometer count (10 squares)X 32* divided by the percentage of granulocytes/100 (decimal)

*dilution factor of unopette

Differentials require practice and experience on the part of the veterinarian or technician performing the analysis. Several good references exist to help develop proficiency in identifying the various white blood cells. The following characteristics are typical of the different cell types:

Heterophils

Heterophils are the most common leukocyte in the peripheral blood of most avian species. They tend to be round cells with a colorless cytoplasm containing eosinophilic or basophilic rod-shaped granules (the granules may be spherical in some species). Heterophil granules usually have adistinct central body that appears refractile. Mature heterophils have a lobed nucleus (usually two or three lobes) with a coarse, clumped chromatin that stains purple. The nucleus is often partially hidden by the cytoplasmic granules.

Heterophils
Heterophils

Eosinophils

Avian eosinophils are typically round but have a greater tendency toward irregularity than do heterophils. The cytoplasm stains a clear, pale blue (in contrast to the colorless cytoplasm of heterophils) and contains round eosinophilic granules (or rod-shaped in some species). In most birds, the granules of eosinophils have different staining qualities from heterophil granules from the same blood smear. The eosinophil granules may appear duller or brighter than the heterophil granules. Eosinophil granules tend to lack the central body found in heterophil granules. Eosinophil nuclei are lobed with coarse, clumped chromatin that stains purple, and the eosinophil nucleus often stains bluer and is usually more noticeable than the heterophil nucleus.

Basophils

Avian basophils tend to be round cells with a round, centrally located nucleus. The nucleus stains a light blue and is often hidden by the cytoplasmic granules. The cytoplasmic granules are deeply basophilic and may dissolve or coalesce in Wright’s stain (or other alcohol-solubilized stains). We rarely see basophils because they may dissolve or coalesce in Wright's stain(or other alcohol-solubilized stains like Hema 3).

Lymphocytes

Lymphocytes are the most common leukocyte found in the peripheral blood of some avian species. They can be classified into three groups according to cell size (small, medium, and large). Most normal mature lymphocytes in the peripheral blood are small or medium. Lymphocytes are typically round cells but often show irregularity due to molding around adjacent cells in the smear. The nucleus is usually round (occasionally indented slightly) and centrally located. The nuclear chromatin is densely clumped or reticulated. The nucleoplasm is often colorless in lymphocytes with a reticular chromatin, and dark in those with dense chromatin clumping. The amount of cytoplasm varies from a narrow band surrounding the nucleus in small lymphocytes to a moderately wide band in medium and large lymphocytes. A high nuclear to cytoplasmic ratio is typical of lymphocytes. The cytoplasm is homogenous and weakly basophilic. Occasionally, lymphocytes have irregular cytoplasmic projections or blebs.

Lymphocytes
Lymphocytes

Monocytes

Monocytes are large leukocytes that are irregular in shape. The nuclei vary from round to bi-lobed and often have a delicate, lace like reticular chromatin. Chromatin clumps may be present but are few in number. The cytoplasm of monocytes stains blue-gray with a finely granular appearance and occasionally contains vacuoles. The cytoplasm may contain two distinct zones; a light-staining area and a more deeply stained area. Monocytes occasionally contain fine (dust like) eosinophilic cytoplasmic granulation.

Thrombocytes

These cells can be confused with lymphocytes, so care must be taken not to count them as part of the WBC differential count. Mature thrombocytes are oval cells that are smaller and more rounded than mature erythrocytes. The thrombocyte nuclei are larger in relation to the amount of cytoplasm and more rounded than erythrocyte nuclei. The nuclear chromatin is dense and clumped. The cytoplasm is clear but not homogenous and often has a reticulated appearance. Avian thrombocytes frequently contain one or more red granules at the poles of the cell. Thrombocytes tend to clump in peripheral blood smears, which aids in their identification.

Thrombocytes and Heterophils
Thrombocytes and Heterophils

(Descriptions courtesy of Carolyn Corsiglia; Good reference: Campbell, Avian Hematology)

2.3.3.3. Chemistry analysis

Micro chemistry techniques are required for such small volumes and are available, but not with every diagnostic pathology laboratory. You must locate a lab that can perform the tests you want on the volumes you want (see APPENDIX for suggested diagnostic laboratories). There are no special "avian" requirements for general chemistry tests (including thyroid), and tests can be performed as they would on dog or cat serum. Individual tests using dry chemistry techniques can often be run on 10μl (0.01 ml) of serum.

Note that in birds, uric acid is used as an indicator of renal function, and in psittacines, AST is most predictive of hepatic insult although still not a very specific indicator of hepatocellular damage. Bile acids are now being used more and more in the diagnosis of liver disease in birds.

"Big 3" - A quick and easy emergency monitoring test using only 2 hematocrit tubes of blood can predict PCV, TSP, and blood glucose. Note that the azostick test has been dropped from the usual "Big 4".

2.3.3.4. Normal Hematologic and Biochemical Parameters of some species of birds

Parameter

A.Grey

Amazon Parrot

Budgie

Cockatiel

Cockatoo

Duck

Owl

Hawk

Ostrich

WBC (x 103)

5-11

6-11

3-8

5-10

5-11

4.5-13

6-25

8-26

8-25

Heterophils (%)

45-75

30-75

45-70

40-70

45-75

30-70

-

-

55-85

Lymphocytes (%)

20-50

20-65

20-45

25-55

20-50

20-65

-

-

10-40

Monocytes (%)

0-3

0-3

0-5

0-2

0-4

0-3

-

-

0-1

Eosinophils (%)

0-2

0-1

0-1

0-2

0-2

0-4

-

-

0-2

Basophils (%)

0-5

0-5

0-5

0-6

0-5

0-5

-

-

0-1

PCV (%)

43-55

45-55

45-57

45-57

40-55

30-43

41-42

36-46

40-55

RBC (x 106)

2.4-4.5

2.5-4.5

2.5-4.5

2.5-4.7

2.2-4.5

2.3-3.5

2.2-3.2

2.4-3.6

2.5-4.5

Parameter

African Grey

Amazon Parrot

Budgie

Cockatiel

Cockatoo

Pigeon

Duck

Ostrich

Total Protein (g/dl)

3-5

3-5

2.5-4.5

2.2-5

2.5-5

2.1-3.3

2.5-6

3-4.4

Glucose (mg/dl)

190-350

220-350

200-400

200-450

190-350

232-369

150-300

170-240

Calcium (mg/dl)

8-13

8-13

6.5-11

8.5-13

8-13

7.6-10.4

10-18

16.3-19.6

Phosphorus (mg/dl)

3.2-5.4

3.1-5.5

3.0-5.2

3.2-4.8

2.5-5.5

1.8-4.1

-

10.7-16.7

Potassium (mEq/L)

2.6-4.2

3.0-4.5

2.2-3.9

2.5-4.5

2.5-4.5

3.9-4.7

3.0-4.5

2.2-6.5

Sodium (mEq/L)

134-152

136-152

139-165

132-150

131-157

140-150

130-155

130-155

Uric Acid (mg/dl)

4-10

2-10

4-14

3.5-11

3.5-11

2.5-12.8

2-12

9-13.3

Alkaline Phos (U/L)

20-160

15-150

10-80

20-250

15-255

140-320

-

130-230

AST (U/L)

100-350

130-350

150-350

100-350

150-350

45-123

5-100

150-230

ALT (U/L)

6.4-13

5-11

5-10

5-11

6-12

15-25

-

16-25

LDH (U/L)

150-450

160-420

150-450

125-450

225-650

30-205

150-800

229-800

Thyroxine (T4)

0.3-2.0

0.05-1.0

2.5-4.4

0.7-2.4

0.8-4.4

0.47-2.73

0.8-3.3

-

Triglyceride (mg/dl)

45-145

49-190

105-265

45-200

45-205

-

-

-

Cholesterol (mg/dl)

160-425

180-305

145-275

140-360

145-355

-

-

90-150

2.3.3.5. Serology, protein electrophoresis and other specific diagnostic tests

Various serology tests are available for chlamydophila, giardia, aspergillus and many viral diseases. These tests are discussed in sections dealing with the specific disease. Protein electrophoresis in conjunction with serologic tests and other diagnostic parameters has been used to help determine a diagnosis of some of these diseases, however, the accuracy of this strategy is in question. Protein electrophoresis is routinely offered in conjunction with other chemistries or serology by the University of Miami diagnostic laboratory.

2.3.3.6. Sex determination

Blood sampling for sex determination
Blood sampling for sex determination

Most psittacine species (especially South American) are sexually monomorphic. Individual owners as well as breeders often want to know the sex of their bird. The traditional method for sexing has been surgical (laparoscopy, discussed later), however less invasive techniques are now available.

DNA sexing through a blood sample is the technique which has been most successful. This technique requires only a drop of blood providing sufficient DNA to perform the test with a specially developed DNA probe. The laboratory that originated this test (ZOOGEN ) is also now keeping DNA records on every bird as a method of identification (DNA fingerprinting) for future reference.

Laparoscopy is still performed as a reproductive tool to better evaluate the exact condition of the reproductive organs and to predict breeding readiness, problems, etc.

2.3.4. Radiology

Radiology is an essential diagnostic tool in pet bird medicine practice. It is often part of a routine workup, along with cultures and blood work. Radiographs provide supplemental information often missing from physical examination and allows more accurate assessment of the skeletal system (fractures etc.), respiratory system (lungs and air sacs), gastrointestinal system (size and position of esophagus, proventriculus, ventriculus, intestine, cloaca), and assessment of other internal organs -liver, spleen, kidneys, gonads and uterus.

Details of avian radiography will be covered in an upcoming lecture.

2.4. Basic therapeutic choices - General medications

Most medications needed for avian practice are readily available and are often routinely kept in any veterinary practice. Each individual veterinarian will develop their own preferences for antibiotics and treatments of commonly encountered diseases. One should design a pharmacy based on the most commonly encountered diseases, bacterial spectrum, and the most convenient preparations available.

Basic Avian Pharmacy List

  • Tube feeding formula

  • Parenteral fluid solutions - lactated Ringers, 5% dextrose, saline

  • Parenteral vitamin/mineral solutions - Vitamin A and D3, B complex, Vitamin K1, Vitamin E/selenium, calcium, iron dextran

  • Antibiotics - Trimethoprim-sulfa, oxytetracycline, doxycycline, enrofloxacin

  • Nystatin

  • Oxytocin

  • Glucose, 50%

  • Calcium disodium edetate

  • Diazepam

  • Isoflurane anesthetic gas

2.4.1. Fluid therapy

As in general medicine, fluid therapy is the backbone of good medical technique. The principles in avian medicine are basically the same as in other animals with few exceptions.

2.4.1.1. Evaluation of hydration status

  • History: anorexia, diarrhea, polyuria, dyspnea/hyperventilation, heat stress

  • Physical appearance: dull sunken eyes, tacky oral mucous membranes, increased skin turgor

  • PCV, TSP - may be helpful and/or misleading

  • Body weight monitoring (once or twice daily)

2.4.1.2. Estimation of hydration needs

Estimation of hydration needs

  • Daily maintenance requirements of

    • 60-100 ml/kg/day

    • OR 1 to 1.5 x MEC in ml/day = 1 to 1.5 x (78 X BWkg0.75)

  • PLUS estimate of dehydration (percent)

  • PLUS continuing losses

2.4.1.3. Choice of fluids

Choice of fluids to use for maintenance and supplementation is made based on the same principles used in mammals and include normal saline, 5% dextrose, lactated Ringers, and the various colloidal solutions such as dextrans and hetastarch.

2.4.1.4. Methods of fluid administration

Methods of administration can involve any of the following, depending on the situation at hand. The colloidal solutions must be given intravenously or through an intraosseous catheter.

  • Oral fluids - gavage

  • Subcutaneous fluids - inguinal, lumbar, patagium (wing). The use of subcutaneous fluids is the most common technique and is very successful unless rapid fluid delivery is required (shock, severe dehydration, acute blood loss, hypovolemia).

  • Intravenous fluids - cutaneous ulnar/brachial v. jugular vein, medial metatarsal vein; a 24 ga. catheter may be placed in most sites in any bird larger than a cockatiel

  • Intraosseous fluids - distal ulna or proximal tibiotarsal bone

IO Catheter
IO Catheter

2.4.2. Therapeutic administration

The condition of the patient, and the formulation of medication required, will often dictate the method of therapeutic administration . The following techniques are commonly used:

Shock Therapy
Shock Therapy

  1. Oral administration: Substances are administered either via crop gavage or directly per os, if the substance is palatable and the patient is cooperative. Oral administration should not be used in severely depressed or weak individuals, or in cases of vomiting or GI dysfunction.

  2. Subcutaneous administration - inguinal, lumbar, patagium (wing)

    Injection Sites
    Injection Sites

  3. Intramuscular administration: Intramuscular is the most commonly used method of administration and is often easier than oral administration, especially in hospitalized patients. The preferred site is in the pectoral muscles either side of the sternum. Injections in the legs should be avoided.

  4. Intravenous administration - cutaneous ulnar/brachial v., jugular vein, medial metatarsal vein

  5. Intraosseous administration - distal ulna or proximal tibiotarsal bone

  6. Nebulization : This technique delivers medications and moisture to the respiratory tract, targeting the sinuses and the air sacs. Both of the sites are poorly vascularized and may not receive adequate levels of parenterally administered medications. Consequently nebulization is often a helpful adjunctive therapy in respiratory diseases.

    Nebulization
    Nebulization

3. Poultry or "Flock" Diagnostic and Therapeutic Techniques

Although pet bird medicine often utilizes hematology and clinical chemistry to help establish a diagnosis, such tests are almost never employed with poultry. A necropsy is the diagnostic procedure most often used in establishing a diagnosis when a disease outbreak occurs in a poultry flock. The most import diagnostic material that one can submit to a diagnostic laboratory are one or two live birds showing representative clinical signs of disease in addition to a few recently dead birds that have also shown typical disease signs prior to death.

Physical examination of a live bird is usually helpful in establishing a diagnosis. The feather cover should be examined and chickens should be assessed to determine if molting is in progress. The feathers should also be examined for presence of external parasites. Ataxia, tremors, paralysis, abnormal gait or leg weakness should be evaluated. Respiratory difficulty, depression or blindness should also be determined. It is sometimes helpful to examine poultry while they are confined to a cage and accustomed to their surroundings. Sometimes it is also important to observe birds 24 - 48 hours after they have been removed from the flock to determine if signs of recovery have occurred. This is especially helpful in the diagnosis of transient paralysis, respiratory infection, chemical toxicity, feed or water deprivation and overheating.

3.1. Collecting blood samples in poultry

Blood samples are sometimes collected for serologic tests in order to confirm the diagnosis of some of the common viral diseases. These samples are usually drawn from one of the following sites:

  • Brachial (wing) vein - least traumatic

  • Heart puncture - usually at the thoracic inlet. This site is less favorable as it is associated with a variable number of fatalities depending on the skill of the bleeder.

Since serum is used for most of these tests anticoagulants are not required. If unclotted blood is required the same anti-coagulants commonly used for mammalian blood can be employed for avian blood (EDTA, heparin, oxalate).

Serology is frequently used to establish a diagnosis for the following diseases:

  • Pullorum disease

  • Mycoplasmosis

  • Newcastle disease

  • Infectious bronchitis

  • Avian influenza

  • Infectious bursal disease

3.2. Antibiotic use in poultry

Antibiotics used in the treatment of bacterial diseases in poultry that produce eggs or meat for human consumption needs careful consideration. Residues in human and animal food products has been a long debated issue in the veterinary profession. These residues can potentially result in antibiotic resistant strains of bacteria that cause human disease.

The following antibiotics are currently approved for use in egg laying hens.

  • Bacitracin (oral)

  • Chlortetracycline

  • Novobiocin

  • Lincomycin (oral)

  • Oxytetracycline

  • Penicillin

  • Salinomycin

  • Sulfadimethoxine

  • Virginiamycin (oral)

For more information on drugs approved for poultry, and withdrawal times go to the FARAD website at http://www.farad.org/

4. References and Resources

4.1. Products mentioned in the text

Microtainer, Becton-Dickson,1 Becton Drive Franklin Lakes, NJ USA 07417 201.847. http://www.bd.com/

Eosinophil Determination kit Test 5877 from Becton-Dickinson, 1 Becton Drive Franklin Lakes, NJ USA 07417 201.847. http://www.bd.com/

Zoogen, Inc . 29280 Mace Blvd. P.O. Box 1157, Davis, CA 95616 (800) 995-2473 (530) 750-5757 FAX: (530) 750-5758. DNA sexing and fingerprinting. http://www.zoogen.biz/

Compounding Pharmacies

BioServ, One 8th St. Suite 1, Frenchtown, NJ 08825 908-996-2155 http://www.bio-serv.com

Hopkinton Drug, 52 Main Street Hopkinton, MA 01748 (508) 435-4441

Island Pharmacy Service, Inc., PO Box 1412 Woodruff, WI 54568 (715) 358-7712

Mortar & Pestle Pharmacy, PO Box 12124 Des Moines, Iowa 50312 (800)-279-7054

4.2. Texts and articles

Altman, Robert B., et al. Avian Medicine and Surgery . Philadelphia. W.B. Saunders Co., 1997. Chapters 9, 10, 11, 12, 17.

Campbell, Terry W. Avian Hematology and Cytology. 2nd ed . Ames: Iowa State University Press, 1995.

Cray, Carolyn, Gregory Bossart, and Don Harris. Plasma protein electrophoresis: principles and diagnosis of infectious disease. 1995 Main Conference Proceedings of the Association of Avian Veterinarians , August 28 - September 22, 1995.

Harr, Kendal. Clinical chemistry of companion avian species. Veterinary Clinical Pathology , v. 31 (3), 2002: 140-151.

Harrison, Gregg J. and Teresa L. Lightfoot. Clinical Avian Medicine . Palm Beach, FL : Spix Pub., c2006. Chapters 9, 10, 21-23.

Hoefer, Heidi L. et al. The use of bile acids in the diagnosis of hepatobiliary disease in the parrot. Proceedings of the 1991 Annual Conference of the AAV , Chicago, Illinois, September 23-28, 1991, pp.118-119.

Oglesbee, Barbara L., Hamlin, Robert L., Klingaman, Heather, Cianciola, Janin, Hartman, Stephen P. Electrocardiographic Reference Values for Macaws ( Ara species) and Cockatoos ( Cacatua species) Journal of Avian Medicine and Surgery 2001 15: 17-22

Ritchie, Branson W., et al. Avian Medicine: Principles and Application . Lake Worth, Fla.: Wingers Publishing, c1994: Chapters 8, 9, 10, 11, 15.

Steinhort, Lani A. Avian fluid therapy. Journal of Avian Medicine and Surgery , 13(2), 1999:83-91.

Stone, E.G. and P.T. Redig. Preliminary evaluation of hetastarch for the management of hypoproteinemia and hypovolemia. Proceedings of the Annual Conference of the Association for Avian Veterinarians , 1994.

Tatum, Lisa M., et al. Protein electrophoresis as a diagnostic and prognostic tool in raptor medicine. Journal of Zoo and Wildlife Medicine 31(4), 200: 497-502.

4.3. Multimedia

VIDEOTAPES: Techniques in Avian Medicine, Part I and II. Veterinary Learning Systems, 1993.