The ability to hide clinical signs until the late stages of disease, together with the high metabolic rates in birds, can result in oxygen deprivation and death during treatment or diagnostic sampling. Thus, diagnosis and treatment must be performed in a step-wise fashion, with constant reevaluation of the bird's ability to tolerate further procedures. Good client communication will allow the owner to understand the potential severity of the bird's condition and the need for patient reassessment as diagnosis and treatment proceed.
The bird should be brought in its own cage if practical. Some tentative diagnoses (eg, zinc toxicity from galvanized wire or dishes, bacterial overgrowth in the environment, inappropriate perches, territorial or sexual behavior, and nutritional disorders) can be based on examination of the cage.
Practitioners should be familiar with normal behaviors of the common avian species. Individual species behaviors that can facilitate the physical examination are discussed below.
Some behaviors can be mistaken by the owner or the veterinarian as signs of illness. A prime example is in Pionus spp parrots. These birds often make very rapid sniffing noises when alarmed, which can be mistaken for respiratory distress.
As prey animals, birds exhibit “masking” behavior to hide signs of illness. Masking behavior may include continuing to vocalize, keeping the feathers smooth (as opposed to fluffed as when ill or sleeping) and exhibiting exaggerated eating behavior. Captive raised birds exhibit this masking behavior to varying degrees. However, astute owners may recognize minor behavioral differences in their hand-raised bird, such as not vocalizing in the morning, or not joining the family to interact or eat. These changes should be considered potential signs of illness. Owners with less experience or less interaction with their birds are not as likely to notice these early signs. Feathers can effectively mask even severe emaciation or abdominal distention. Birds with such problems often present in more advanced stages of decompensation.
The length of time that a bird has been in the household is inversely proportional to the probability that illness will be due to a primary infectious disease. Newly acquired birds or those exposed to other birds outside the household via bird shows or pet store visits are most likely to be affected by contagious diseases. Chronic malnutrition and secondary infection are more common in birds without recent exposure to potentially infectious psittacines. Malnutrition is a major cause of subclinical disease in birds, which often becomes clinical when a secondary infection occurs.
A thorough history should include the source of the bird, whether it was raised by its parents or by hand; previous medical conditions or treatments; current diet (both what is offered and what is actually consumed); and current environment, including caging, changes in diet or caging, other pets in the household and the bird's interaction with them, recent interaction with other birds, temperature and humidity at which the bird is maintained, indoor and outdoor exposure, and photoperiod regulation.
The clinician should observe the bird and note its behavior prior to restraint. If possible, observe from a seated position, in order to decrease a perceived predatory threat and allow the bird to relax. Open-mouthed breathing, panting, marked tail bobbing, increased respiratory effort, or audible respiratory sounds should be noted. If these signs of respiratory impairment are present, subsequent handling may need to be abbreviated. Birds that are ill may smooth their feathers briefly upon entrance of the clinician, but soon resume a fluffed and sleepy appearance. While the presence of this classic fluffed “sick bird” presentation is significant, its absence is not a guarantee of wellness.
Handling techniques should be designed to minimize stress. Some birds are towel-trained to accept the towel as a refuge, which can minimize stress during handling. Also, birds may have been trained to allow the owner to groom their nails or wings. The degree to which the owner is allowed to assist in the veterinary office will vary with the practitioner, the owner, and the situation. Regardless of the owner's involvement, attention must be paid to the psychological effect of the veterinary visit on the bird. Certain species, particularly African Grey parrots (Psittacus erithacus) are noticeably sensitive and prone to the development of phobias. Quiet talking and eye contact can often soothe these birds during restraint.
Practitioners should be familiar with techniques that can be used in the animal hospital as well as basic behavioral tendencies of different species. For instance, Umbrella cockatoos (Cacatua alba) of any age will usually allow a complete examination while cuddled to the practitioner's body, and will allow the mouth to be held open sufficiently to do a thorough oral examination. These same birds, however, often do not readily step onto a hand. Conversely, most Amazona spp usually will step onto a hand when at an inferior height, but will generally not allow cuddling or comply with an oral exam.
Restraint of psittacines involves immobilization of the head, generally with a thumb on one side of the mandible and the index or middle finger on the other. The feet and the distal reminges (primary wing feathers) are held by the opposite hand in medium to larger parrots. This leaves the thorax and abdomen free to expand with respiration. If the primary wing feathers have been trimmed, a towel may be useful in preventing the wings from flapping during restraint.
The bird's reactions to handling and examination must be monitored during restraint. If respiration becomes excessively labored, the bird's grip with its feet weakens, or it fails to move its head when manual restraint is lessened, it may not be getting enough oxygen and should be returned to the cage or table. Severely ill birds may not tolerate even minimal handling or repositioning; placement of the entire cage into an oxygen-rich, humidified, heated enclosure may be needed prior to any procedures.
Obtaining an accurate weight is essential for monitoring health or recovery from illness. The general condition of the feathers and skin should be noted, including the symmetry and integrity of the beak and nails. Pectoral muscling can be used as a rough guide to a bird's general body condition. However, although obese birds may carry some excessive fat over the pectoral muscles, much of it is deposited subcutaneously over the neck, thighs, and in the sterno-pubic area, especially in Amazona spp. The wings and legs should be symmetric in their degree of extension, flexion, range of motion, and strength of grip. The joints should likewise be symmetric and nonpainful on palpation. Matted feathers over the cere indicate nasal discharge. More excessive dried debris over the head usually indicates vomition.
Respiration may increase during restraint due to stress, hyperthermia, underlying disease, or obesity. Panting, when it occurs, should abate within ∼3 min after release, or underlying cardiopulmonary disease may be present. Auscultation of the lungs can be performed over the dorso-cranial thorax. Arrhythmias may occur, but can be difficult to categorize due to the rapid heart rate of birds. The cloaca should have sufficient tone to provide tight closure.
Routine Grooming Procedures
Wing clipping is frequently requested by owners. Communication about wing trims is vital. Owners may assume that a wing trim is required at regular intervals. In captivity, however, the frequency at which feathers are molted varies widely. The fact that a wing trim is a deterrent to flight, not a guarantee, should be emphasized. A bird that can only glide to the ground indoors may be able to fly outdoors on a windy day. The degree and purpose of a wing trim should be discussed with the owner. The basic types of wing trims are: 1) Removing 4–7 of the distal primary flight feathers from both wings, below the level of the coverts. The number of feathers that must be removed is inversely proportional to the bird's weight. 2) Leaving 1–4 distal primary feathers and removing the remainder of the primaries from both wings. This clip has fallen out of favor, but some owners have used it for many years. If it has worked well for their bird, it may be wise to continue its use. 3) Removing a variable number of primary feathers from just 1 wing. This clip is unnecessarily severe in most cases, but some owners have found it a useful and effective deterrent to flight. Some smaller birds are able to compensate by holding their tails to the side and are still able to fly even with all primary reminges trimmed.
Excessively aggressive wing trims, especially when they are performed at the same time as a nail trim, can cause both physical and psychological damage to birds. The sudden lack of stability and lift can cause them to fall, possibly injuring either the carina of the keel or the beak. Psychologically, this lack of stability can lead to insecurity and serious behavioral problems.
Nail trimming is often requested, frequently for the owner's comfort and not due to any true overgrowth of the nails. However, nail trimming decreases the bird's stability and increases the chance that it will fall from its perch. Generally, a compromise can be reached by blunting the needle-like tip while still leaving sufficient nail to allow a stable grip.
Various types of equipment can be used for nail trims, depending on the size of the bird. Human fingernail trimmers work well to remove the tips of the nails from very small birds. Cat claw trimmers, White's nail trimmers, and hobby drills with sanding bits are all useful. The sanding tools are also excellent for removal of excess keratin that can accumulate on the lateral surfaces of the beak. Birds with beak deformities often have underlying nutritional deficiencies, disease, or previous trauma. Normal, healthy birds that are provided with adequate environmental abrasive surfaces rarely require beak trims.
Concrete (cement) perches are available in various sizes and textures. These can work well for medium-sized psittacines (∼250–700 g) when a suitable size is selected and properly placed in the cage. These perches eliminate the need for both nail trimming and removal of excess keratin from the beak. The perch should be placed where the bird is forced to stand for brief periods (eg, in front of a food bowl or treat cup). To avoid irritation to the plantar surfaces of the feet, the concrete perch should not be the main perch on which the bird sits to preen or sleep.
In previous decades when parrots were widely imported, open-rolled steel bands were used to identify the location at which they were quarantined. Now most birds are leg banded (using closed bands) as chicks for individual identification. Bands present certain hazards to the bird, but removal also entails some risk if the proper equipment is not available. The open (gap present), rolled, steel quarantine bands are extremely strong and require removal by a full-size bolt cutter with sharp edges. The closed aluminum bands placed on young, captive-raised birds, must be stabilized to prevent twisting while being cut. These bands require 2 cuts to remove; a sharp, properly designed instrument for removal decreases the danger of leg trauma. Full circle plastic bands can be removed in the same manner. Microchipping is replacing or augmenting banding as a means of identification. The standard for placement of these chips in psittacines is in the left pectoral muscles. Adverse reactions or failures in birds have been infrequent; the intramuscular placement reduces the risk of microchip migration.
Hematology and blood chemistry are especially important in birds because physical examination tends to be less revealing than in other animals. The quantity of blood that can be drawn depends on the weight and health of the bird. Blood collection should be limited to 1% of body weight and bolus fluid administration to 0.5–1% of body weight. Blood is usually collected from the right jugular vein, which is larger than the left. The basilic (wing) vein can also be used, but is prone to hematoma formation. In medium to larger psittacines, seabirds, and poultry, the medial metatarsal vein can also be used. Coating a syringe with an anticoagulant before collection may be helpful in smaller species in which sample collection may take longer.
The normal hematocrit varies between psittacine species. For example, cockatiels normally have higher PCV than many other birds, averaging 50–55%. Cockatoos (Cacatua spp), however, often have PCV in the low- to mid-40% range.
Normal leukocyte parameters for birds are still being determined. Leukocytosis, and the type(s) of WBC that are increased, can identify underlying disease and give an indication of the most likely etiologies.
Avian RBC are nucleated, so traditional mammalian methods of WBC determination are not adequate. Various diluents (eg, Eosinophil Unopette®, Natt-Herricks® solution) are available to enable accurate WBC determinations. Estimated WBC counts are less accurate, but can be useful when the individual performing the estimate produces blood smears of consistent quality and thickness. Normal total WBC counts vary with species and age (see Normal Hematologic Values in Selected Pet Birds). Adult cockatiels often have total WBC counts of 4,000–7,000 × 103. Adult macaws are usually at the high end of the normal avian range (12,000–15,000 × 103).
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Physiologic differences in birds create variations from accepted mammalian normal values for many biochemical measurements. Due to the excretion of uric acid rather than urea as the primary product of protein metabolism, uric acid levels are significantly higher in birds than in mammals, while BUN is significantly lower. Uric acid may be elevated in severe renal disease or with articular gout (see Miscellaneous Diseases of Pet Birds). Severe dehydration may also increase uric acid levels. No reliable biochemical indicator is currently available to detect early renal impairment.
Serum or plasma glucose is higher in birds than in mammals, with levels of 180–400 g/dL common, depending on species. Levels that indicate diabetes also vary with species and individuals, but often are 650 to >1,000 g/dL (see Miscellaneous Diseases of Pet Birds).
Hepatic enzymes measured commonly include AST and lactic dehydrogenase (LDH), which have normal values several times those of mammals (AST, 10–400 U/L; LDH, 75–450 U/L). Measurement of CPK is often performed concurrently to differentiate increased values of AST due to muscle necrosis from those due to hepatic damage. LDH is a short-lived enzyme of limited usefulness in the detection of hepatic necrosis. ALT levels are very low compared to mammals (5–15 U/L); however, elevations from these low normal levels can indicate hepatocellular necrosis. Birds have low bilirubin reductase levels; therefore, total bilirubin is normally also very low, and elevation with hepatic disease is not consistent (total bilirubin range 0–0.1 mg/dL). Bile acid measurements are useful indicators of hepatic function, with levels <100 mol/L considered normal for most avian species. The establishment of normal values for different avian species will enhance the usefulness of bile acid assays.
Amylase and lipase levels in birds can aid in the diagnosis of pancreatic disease. The frequency of primary pancreatic disease is unknown, but it does occur. Secondary pancreatitis is much more common and is often related to inflammation caused by coelomic conditions such as egg-yolk peritonitis.
Calcium and phosphorus values are similar to those found in mammals. These levels may increase up to 3-fold in the hen in preparation for egg laying (ie, calcium ∼30 mg/dL and phosphorus >10 mg/dL), usually with a relatively normal ratio of these minerals. Total solids as measured via refractometer are significantly lower in birds than in mammals, with levels of 3.0–5.5 g/dL normal for most species.
Routine Medical Procedures
Injections can be given by a number of routes. SC injections are used for fluid administration and some vaccinations, and they are gaining acceptance for the administration of routine medications such as antibiotics. Preliminary studies show that the SC route may be as effective as IM injections for many medications, without the associated muscle necrosis. To ensure that the medication or fluid being injected is actually deposited subcutaneously, the skin must be clearly visualized; use of alcohol is recommended to aid in visualization. Insulin syringes (50 U or 0.5 mL) with 27-gauge needles are invaluable for accurate dosing when small quantities must be administered. SC fluids are often used in birds. In order to maximize their absorption and minimize the stress produced, fluids should be warmed to 102–106°F and hyaluronidase added at 100–150 U/L. Sites of administration include the back, the inguinal web, and the skin over the breast muscle. The medial aspect of the patagium (wing web) may be used but can cause a temporary wing droop or wing discomfort. Maintenance fluids are estimated at 50 mL/kg divided bid-tid. In dehydrated birds, 50% of the total daily maintenance can be administered SC (25 mL/kg) and repeated every 6–8 hr until hydration is reestablished.
IM injections are given into the pectoral muscles in most pet birds; leg muscles are also used in some species, particularly raptors. The muscle fibers of birds are more vascular and tightly packed than those in mammals, making both muscle necrosis and inadvertent IV injection more likely.
IV injections are occasionally indicated in birds. Common medications administered IV include doxycycline, amphotericin B, chemotherapeutics, contrast media, and fluids.
Indwelling catheters can be placed in the jugular, basilic, or media metatarsal veins for constant rate infusions or intermittent fluid administration. Intraosseous catheters can also be inserted, generally in the proximal tibiotarsal bone or distal ulna. A standard hypodermic needle may be used (usually 25-gauge for initial entry, followed by a second 22-gauge needle sutured in place), or a spinal needle with stylet may be used for larger birds. Without a stylet or second needle, a bone plug may obstruct the needle. The intraosseous or IV catheter is intermittently flushed with heparinized saline whenever fluids are not running.
Crop (gavage) feeding may be used to meet caloric needs in anorectic birds. Commercial formulas are available and convenient to use. Adequate hydration must be established prior to initiating crop feeding to prevent desiccation of the crop food and GI stasis. In adult birds, generally 30 mL/kg can be administered tid-qid. Baby birds have a much more distensible crop and will hold about 10% of their body weight per feeding (100 mL/kg). Oral medications may be added to the crop feeding or given directly by mouth. The technique of holding the bird so that the medication is administered into the commissure of the mouth and rolls onto the tongue will minimize stress, loss of medication, and the danger of aspiration. Medications administered in the water are only indicated in special circumstances. Enrofloxacin and doxycyline in water generally provide adequate blood levels for efficacy. However, lack of accurate dosing, stability of the medication, and palatability make this route undesirable in most cases.
Sedation is sometimes desirable for diagnostic or treatment procedures. Isoflurane or sevoflurane anesthesia delivered via face mask can safely sedate most stressed or mildly debilitated birds and provide a rapid recovery. Midazolam at 0.25–1.0 mg/kg, IM is useful to reduce anxiety during restraint and for postprocedural stress, such as placement of an Elizabethan collar.
Intubation in birds is relatively easy, as the absence of an epiglottis facilitates visualization of the tracheal opening and arytenoids. Fasting before anesthesia should be of minimal duration; 4 hr fasts are typical. Regardless of the duration of the fast, the crop should be palpated for the presence of food or fluid prior to anesthesia. Delayed crop emptying is common in clinically ill birds. If anesthesia must be administered to a bird with food or water still in the crop, the head should be elevated for the duration of anesthesia, regardless of whether or not the bird is intubated. Gauze sponges placed in the oral cavity caudal to the glottis further reduce the chance of aspiration. Endotracheal tubes should be uncuffed, because the absence of a tracheal ligament increases the risk of tracheal necrosis if a cuff is overinflated. A small animal ventilator can be employed for most birds as small as 100 g and can greatly improve ventilation during anesthesia. If a mechanical ventilator is not available, manual intermittent positive pressure ventilation has been shown to increase oxygenation in anesthetized birds. A capnograph is also useful for anesthetic monitoring.
Environmental management is very important; severely ill birds benefit greatly from an increased environmental temperature and humidity (eg, use of commercial incubators with temperature and humidity controls). For at-home emergencies, a warm environment can be created by wrapping clear plastic wrap around 3 sides of the cage and placing an electric heating pad on the remaining side. Digital thermometers with remote probes can provide accurate monitoring of environmental temperatures. A quiet location, away from the sound of barking dogs and other excessive activity, will decrease stress.
The cage arrangement can be critical for ill birds. If a perch is supplied, the food and water must be elevated so that the bird has ready access without having to climb down from the perch. Often it is best to remove perches from the cages of ill birds so they can more easily access their food, and so they do not expend energy simply trying to maintain their perched position.
Last full review/revision July 2011 by Teresa L. Lightfoot, DVM, DABVP (Avian)