Pediatric Diseases of Pet Birds
Birds are classified by their maturity level at hatching. Parrots, doves, and finches are altricial, hatched without feathers, with eyes closed, and helpless. Poultry, ratites, and waterfowl are born precocial, with down feathers, open eyes, and the ability to walk and feed themselves at hatching. Psittacine neonates are completely dependent on the parent birds for warmth and food; they also lack a functional immune system and are more susceptible to disease. Because of these characteristics, proper husbandry and nutrition of the chick and parents is critical for their health and survival.
Today, chicks are either parent raised (most small parrots such as budgerigars and lovebirds) or hand raised (large parrots). There are advantages and disadvantages with both methods. Most aviculturists believe that hand-raised parrots make better pets and that incubator hatching and hand raising reduces the incidence of some infectious diseases. Disadvantages of hand raising can include stunting and an increase in husbandry-related diseases such as crop stasis or aspiration pneumonia. Many avian veterinarians and behaviorists also believe that hand raising may lead to behavioral issues because chicks cannot learn species-specific behaviors from parent birds and become imprinted on people.
The health of a chick depends on many factors, such as the health of the parents, genetics, the incubation process, nutrition (type of food, temperature, and consistency), environment (humidity, warmth, and cleanliness), and exposure to infectious diseases. When an ill neonate is presented, the history of not only the chick, but also of its parents, the aviary, and the nursery are important. Is the chick being hand fed or parent fed? Is the chick incubator hatched? How old is the chick? Is the nursery closed, or are chicks taken in from other facilities? What is the temperature and humidity of the nursery? What is the type of food fed, its consistency, temperature, amount fed, and frequency of feedings? What are the cleaning practices?
General environmental temperature guidelines are for newly hatched psittacine chicks, 92°–94°F; unfeathered chicks, 90°–92°F; pin-feathered chicks, 85°–90°F; and fully-feathered and weaned chicks, 75°–80°F.
A diet of 25%–30% solids should be fed to chicks >2 days old (more dilute formula for newly hatched), with the environmental temperature between 102°–106°F. Most medical issues arise in young birds in the first week of life, at fledging, or at weaning.
Physical examination of the chick can typically be done with minimal restraint, and the chick should be kept warm throughout the examination. The crop should be palpated at the beginning of the examination. Birds with food in their crop should be handled carefully to reduce the risk of regurgitation and/or aspiration. Mentation and body weight (a growth chart should be requested from the breeder if possible) should be noted. Before they fledge, chicks have little musculature over their keel bone; therefore, the muscle and subcutaneous fat over the hips, elbows, and toes should be evaluated. It should be determined whether the ears and eyes are open, or when they opened, if known.
The skin, feather quality, and distribution of the feathers should be examined. Healthy chicks have yellowish pink skin, and feathers first appear on the head, wing, and tail. Abnormal feather growth or delayed or abnormal opening of eyes can be a sign of stunting. Stress bars (lucent areas across the vane of the feathers) indicate a period of stress when that portion of the feather was forming. These are common during weaning, so a few stress bars are not uncommon. A large number of stress bars may indicate an underlying illness or condition.
The oral cavity should be moist with no plaques or lesions, and the choana should be examined for blunting of the choanal papilla, which can indicate hypovitaminosis A or chronic respiratory disease. The crop may be quite full in a neonate. The veterinarian should observe for crop contractions and ask when the chick was last fed and how much was fed, to determine whether the crop is emptying normally. Nestlings have a normally distended abdomen because of an enlarged proventriculus and ventriculus from being fed large amounts of formula. Chicks should be handled carefully to avoid placing excess pressure over their abdomen.
The spine, neck, wings, legs, and feet should be examined for abnormal curvature or weakness and evaluated for normal posture. The vent should be clean of debris.
Aspiration pneumonia is one of the most common causes of respiratory disease in hand-fed psittacine birds. Chicks can aspirate while being fed large quantities of liquid formula, especially when being fed by an inexperienced person. Aspiration often occurs as birds begin to wean.
Clinical signs include increased respiration, respiratory distress, poor feeding response, and depression. Depending on the age and size of the chick, a CBC and radiographs may aid in the diagnosis; however, diagnosis is often based on history and physical examination findings.
Treatment consists of oxygen therapy, nebulization, antibiotics, antifungals, warmth, supplemental fluids, and anti-inflammatory drugs. Prognosis is guarded.
The normal gut microflora in chicks is primarily gram-positive bacteria. The presence of large numbers of gram-negative bacteria or budding yeast indicates infection. Bacterial infections can occur from multiple sources: an unsanitary environment, inappropriate storage of formula, and use of unclean feeding utensils.
Clinical signs can include crop stasis, poor feeding response, regurgitation, depression, and dehydration. Diagnosis is based on clinical signs and results of a fecal or crop Gram stain, CBC (leukocytosis, monocytosis), and culture and sensitivity testing.
Treatment is with antibiotics, based on culture and sensitivity results if available, and supportive care. Neonates on antibiotics often develop secondary yeast infections; therefore, prophylactic treatment with an antifungal drug such as nystatin or fluconazole may be warranted (see Table: Antifungals Used in Pet Birds).
Candida albicans can be present in low numbers in a healthy chick but may proliferate in the presence of antibiotic treatment, malnutrition, stress, or immunosuppression. It is the most common fungal infection in young birds and can result in thickening of the crop mucosa, which may be palpable externally and has been described as "Turkish towel in appearance."
Clinical signs are crop stasis, poor feeding response, and depression. There may be lesions or plaques in the oral cavity. Intestinal or gastric candidiasis can result in malabsorption. Diagnosis is with fecal or crop cytology revealing large numbers of budding yeasts.
Treatment is with antifungal medications. Antifungals should be given to baby birds prophylactically when on antibiotic therapy to prevent yeast overgrowth (see Mycotic Diseases of Pet Birds).
The most common viral diseases in psittacine chicks are polyoma virus, avian bornavirus, proventricular dilatation disease and circovirus, and psittacine beak and feather disease (see Viral Diseases of Pet Birds).
Foreign bodies can be found in young birds, including ingestion of substrate, toys, or feeding tubes. Diagnosis is based on clinical signs, history, and radiographs or CAT scan results. Treatment may require an ingluviotomy to gain access to the mucosal surface and lumen of the crop, proventriculus, or ventriculus. Removal of a foreign body, such as a feeding tube, is the most common indication for this procedure in pediatric birds. In larger or older birds, a rigid endoscope may be necessary to visualize and extract upper GI foreign bodies. The endoscope may be used either orally or through an ingluviotomy incision, depending on the accessibility of the foreign body.
Crop stasis, defined as the inability of the crop to empty in a normal time frame, is a common condition in hand-fed chicks. Crop stasis can occur due to poor husbandry and nutritional practices or primary disease. Environmental temperatures that are too cold or inadequate humidity can lead to crop stasis, as can feeding formula that is too cold or thick. All aspects of the nursery and feeding practices should be evaluated.
Clinical signs include a distended crop, dehydration, poor feeding response, regurgitation, and depression. Diagnosis is based on physical examination findings, palpation of the crop, and cytology and/or culture of the crop contents.
Treatment may include physically emptying the crop, fluid therapy, antibiotics and /or antifungals, and providing smaller, more dilute, and more frequent feedings once the crop is emptying.
Crop burns result from feeding baby bird formula that is too hot. This can occur when a microwave oven is used to heat the formula (not recommended because of the formation of hot spots within the formula). Mild cases may result in red and inflamed skin in the area of the crop. Second- and third-degree burns will be acutely inflamed and blistered and may lead to tissue necrosis and fistula formation. In subacute cases, birds may be presented with food draining from a fistula through the crop wall and skin. Diagnosis is based on history, clinical signs, and physical examination findings. Treatment includes antibiotics, supplemental fluids, anti-inflammatory drugs, and nutritional support. Surgical repair is often required but should be postponed until the burned area is well demarcated (usually several days); repair involves debriding devitalized tissues, separating the crop wall from overlying skin, and closing the two layers separately. Prognosis is good if the remaining crop wall is sufficient for closure and the esophagus is intact.
Esophageal and pharyngeal trauma occurs from improper hand-feeding technique, either with the syringe tip or a rigid feeding tube. This leads to tissue trauma, cellulitis, and distribution of food into subcutaneous tissues. Birds may present depressed, anorexic, cold, and dehydrated, with poor feeding response. Swelling may be palpable in the neck area. Diagnosis is based on the history of hand feeding and oral or endoscopic examination to identify the puncture site.
Surgically opening the pockets, flushing the wounds, and allowing for drainage is important in treatment, along with antibiotics, analgesics, anti-inflammatory drugs, and supportive care. Prognosis depends on severity of the lesion, amount of food deposited in the tissues, and how quickly the lesion is detected and treated. In severely traumatized cases, prognosis is guarded to poor.
The liver relative to total body weight is typically larger in neonates than in adult birds, so some degree of hepatomegaly is normal in chicks. However, neonates with hepatic lipidosis typically have the following characteristics: 1) they are usually still being hand fed, often with a commercial formula to which the owners have added peanut butter, oil, or some other high-fat food, and 2) they are usually heavy for their age and exhibit severe respiratory distress. These birds must be handled gently and minimally. Cool oxygenation is the best first step. They have virtually no air sac capacity, and the stress of feeding and breathing at the same time may exceed their oxygen reserves. Drastically reducing the quantity of crop food per feeding, adjusting the content of the formula, and adding lactulose to the formula are the general nutritional changes required. Parenteral fluid supplementation will help keep the initially hyperthermic bird hydrated. When possible, blood samples should be submitted to check for concurrent infection or other diseases.
Hereditary, congenital, and husbandry issues may affect the growth of young birds. Stunted chicks are thin, and the head is disproportionately large. Toes, wings, and hips are thin; eye and ear openings may be delayed. The skin may be dry and without adequate subcutaneous fat. Abnormal feather patterns (swirls) may develop on the head of a stunted chick. Stunting can develop early, in the first 30 days, or shortly after purchase from the breeder. Usually stunting is caused by husbandry and nutritional issues, often because of handlers inexperienced at hand feeding. Inappropriate quantities of hand-feeding formula, incorrect temperature, and incorrect consistency of the formula cause reduced feeding response and/or GI stasis. Birds purchased soon after arriving at the pet store are often mistakenly labeled as “weaned.” In nature, these birds would be eating partially on their own but still receiving supplementation from their parents. When such a bird is sold to an uninformed owner, it usually takes a few days to a few weeks for the bird's insufficient food intake to create noticeable debilitation and weakness. These birds may also have underlying problems, eg, decreased hepatic function or immunosuppression.
Diagnosis is based on the history and physical examination findings. Treatment is supportive (fluids, nutritional support, and warmth). Antibiotics or antifungal drugs may or may not be needed, based on diagnostic test results. Some of these birds will survive, but many will not.
The term splayleg is a catch-all for deformities of the legs in young birds. Often, there are laxities of the ligaments of the stifle and/or angular deformities of the femur, tibiotarsus, and tarsometatarsus. Causes are poorly documented, but risk factors include nutritional deficiencies (consistent with those of metabolic bone disease, see Nutritional Diseases of Pet Birds) and insufficient support or substrate in the enclosure.
Various methods of external coaptation have been devised and are most successful when the bird is young. Placing the chick in a deep enclosure with a suspensory device or cloth that allows the leg to be directed vertically or taping the legs together in a “hobble” may be corrective if implemented early. Stifle subluxation can develop because of disruption of the cruciate and /or collateral ligaments. Surgery (osteotomy and external skeletal fixator) may be used for rotational deformities.
Mandibular prognathism commonly occurs in several birds from the same clutch and is seen most commonly in cockatoos. If detected early, the hand feeder may be able to correct prognathism by pulling the beak upward and out for several minutes, several times a day. In older chicks, the condition may require a prosthetic that pulls the upper beak out and over the lower beak. This can be cumbersome and painful, and the prosthetic often needs to be reapplied. Trans-sinus pinning is a more recent and more reliable method of correction but carries some risk.
Scissor beak is a lateral deviation of the upper or lower beak. This may be caused by improper incubation temperature or possibly genetic factors in some chicks. If detected early, mild scissor beak can be corrected by manually placing a counter force on the beak for several minutes 2–3 times daily. More severe defects may require placing a beak prosthetic.
Constricted toe syndrome is fairly common in neonates, often affecting more than one digit. An annular band of fibrous tissue forms at a joint of the digit, impeding circulation. The cause is unknown, although either excessively low or high humidity and septicemia have been proposed. This syndrome is most common in Eclectus parrots and macaws, usually in chicks housed in environments with inadequate humidity.
When detected early, debriding the annular band and applying a moist dressing is often effective. In more severe cases, small longitudinal incisions can be made on the medial and lateral surfaces of the affected toe to allow for swelling and to promote circulation. If circulation loss is severe and necrosis is apparent, amputation may be necessary. NSAIDs can be used to reduce inflammation and pain. A bandage will protect the site from contamination and secondary infection. Early detection and intervention is critical in successful treatment.
Toe malposition usually involves the lateral or fourth toe, which points forward instead of backward. If discovered early, malposition is easily corrected by taping the toe in a normal position. In young birds, the foot can be bandaged with the toe pointing backward in the normal position for several days. Older chicks may need prolonged bandaging.
Cryptophthalmia is most commonly seen in cockatiels and is often observed in clutch mates. The condition is usually bilateral. The eyelids, if present, are generally normal in conformation but greatly reduced in length, leading to small to nonexistent palpebral fissures. If the palpebral fissure is sufficient to allow functional vision, no correction is needed or recommended. Extending the palpebral fissure by conjunctival eversion can be performed with modest success when the palpebral aperture is absent or reduced and functional vision is compromised.
Bordetella avium is the causative agent of a syndrome that can appear in clutch mates, most commonly in cockatiels. Bacterial invasion from the sinuses progresses to the skeletal muscle of the mandible, resulting in a myositis and "lockjaw." Treatment is antibiotics and supportive care. Manually opening the beak can be difficult, so feeding and medicating the bird can be challenging. Prognosis is guarded to grave.
Choanal atresia is seen most commonly in African grey parrots but has also been documented in other species. With choanal atresia, the communication between the nares, infraorbital sinus, and the choana is incomplete or absent. Clinical signs are increased mucus accumulation and possible infection in the nares and sinuses. Blunted choanal papilla may be detected on oral examination. Diagnosis is by endoscopic examination of the choana.
Atresia can be treated by creating an opening in the choana through the nares with an intramedullary pin. A red rubber feeding tube is then threaded through the nares, out the choana, and back behind the head of the bird and is left in place for 2–3 wk. This procedure is usually performed in stages, beginning with a small tube first and following with a larger tube.