- Crop stasis is one of the most common problems seen in psittacine chicks.
- Lateral deviation of one or both legs (“splay leg”) is also commonly seen. Housing chicks on flat, smooth surfaces can worsen this condition.
- Chicks near weaning are most commonly presented with aspiration pneumonia because they tend to resist feeding.
- Careful, experienced hand feeding technique reduces the risk of many potential problems including crop stasis, crop burn, hepatic lipidosis, pendulous crop, some beak malformations, and aspiration pneumonia.
The key to hand raising healthy psittacine chicks is a strong preventive medicine program based on sound husbandry practices (Fig 1). Hygiene, hand feeding protocols, incubation and brooder parameters, environmental temperature in the nursery, and pest control are just a few of the husbandry practices that; if mismanaged, can lead to serious adverse consequences.
Many experienced aviculturists follow strict husbandry protocols that result in few health problems. When problems do arise, they can identify the source of the problem and minimize morbidity and mortality. The development of proven psittacine avicultural techniques has led to an increase in the number of bird enthusiasts making the transition from pet owner to aviculturist. It is in this group of aviculturist that I tend to see the most serious health issues—most of which can be traced to improper management techniques. It is with this group of new aviculturists that we can make the greatest difference as avian veterinarians. The development of a strong relationship with the aviculturist will encourage sound husbandry practices that in the end will lead to an increase in the number of healthy chicks produced.
Conditions affecting the gastrointestinal system and associated organs
Delayed crop emptying is one of the most common problems seen in psittacine chicks. More often than not, improper management such as cold feeding formula or cold environmental temperature causes crop stasis. Crop stasis in turn can result in overgrowth of Gram-negative bacteria and/or yeast within the gastrointestinal tract.
If not treated promptly and aggressively, crop stasis can lead to severe dehydration, septicemia, and death. The first priority is to clean the crop and initiate supportive care. In some cases oral fluids can be used to soften inspissated crop contents, which may then be removed through a feeding tube. Repeat this procedure several times until the crop is clean, but take care when aspirating crop contents. The crop wall is fragile and can be damaged by aggressive suction.
Fluids are crucial in the treatment of crop stasis. Many patients will benefit from subcutaneous fluids, but administer intravenous fluids to severely dehydrated chicks. Once the crop is emptied, give a small amount of fluid by tube and wait a few hours before feeding. Initially provide smaller volumes of formula more frequently. It may also be prudent to offer more dilute formula for the first feeding or two. Metoclopramide (0.5 mg/kg IM initially, then PO every 8 hrs) and cisapride (0.5 mg/kg PO every 8 hrs) can be used as gastrointestinal motility stimulants.
Crop burns are usually caused by feeding excessively hot formula (>110°F), particularly formula heated in a microwave without thorough mixing. Early signs of crop burn may be missed, but may include hyperemia, edema, and blister formation. More often the first sign noticed is the formation of a necrotic area at the burn site, or formula spilling from the crop through a fistula after the necrotic tissue sloughs.
Allow a clear line of demarcation to develop between necrotic and healthy tissue before surgical correction (Fig 2). This usually takes 10-14 days after the initial insult. Surgical correction involves correction of the fistula and closure of the crop and skin in two separate layers.
Foreign body or impaction
Many neonates ingest bedding or small objects within their enclosure due to their curious nature. Non-specific signs of illness and vomiting may be observed. Survey radiographs and upper gastrointestinal contrast studies will facilitate the identification of foreign bodies and impaction.
- Remove crop foreign bodies such as feeding tubes or large food items using gentle, retrograde manipulation through the oropharynx.
- Severe crop impactions with bedding material or lower gastrointestinal impactions require surgical intervention.
- Remove foreign bodies within the proventriculus and/or ventriculus with the aid of a laparoscope. In small birds the endoscope can be inserted through the oral cavity, but most birds require an incision into the crop.
When baby birds are fed an excessive volume per feeding this leads to over-stretching of the crop. The crop becomes flaccid and extends ventrally over the cranial edge of the sternum. If not corrected, this problem can lead to crop stasis, malnutrition, stunting, and secondary bacterial and fungal infections of the gastrointestinal tract.
Apply a “crop bra” to provide ventral support using a soft cloth or elastic bandage material (Vetrap, 3M). Check the bra daily and replace the bra twice weekly until the condition is corrected. Reduce the amount fed and increase the frequency of feedings until the problem is corrected. Severe cases may require surgical resection of a portion of the flaccid crop.
The two most common abnormalities are lateral deviation of the maxilla (scissor beak) and mandibular prognathism. Scissor beak is most commonly found in macaws, whereas mandibular prognathism is most common in cockatoos. Scissor beak has been associated with improper hand feeding technique. Large birds that are always fed from the same side may suffer unilateral damage to the developing beak. In very young birds, physical therapy and corrective grinding may correct the problem. As the beak hardens, acrylic implants or extensions are required for repair.
Hepatic lipidosis is most commonly seen in cockatoo and Amazon parrot (Amazona spp.) chicks fed excessive amounts of formula or a high fat diet. Affected chicks usually present with severe hepatomegaly. Evaluate feeding protocols and fat content of the formula and place the chick on an appropriate feeding schedule. If the chick is dyspneic secondary to air sac compression, reduce the amount of formula fed and increase the frequency of feedings. Treatment should be directed at supporting liver function.
Leg and toe deformities
“Splay leg” or lateral deviation of one or both legs is commonly seen in baby birds. Housing chicks on smooth, flat surfaces that do not provide traction can worsen this condition. In young birds, placing chicks in a circular container and packing the legs in a normal position using towels or tissue can correct leg deformity. Severe cases or abnormally directed toes require hobbling or braces made with malleable splint material (Sam splint Jorgensen laboratories, Loveland Co). Leg and toe deformities respond relatively well to conservative treatment if done early. As the bird matures, deformities require surgical correction.
Constricted toe syndrome
Constricted toes are commonly seen in macaws, African grey parrots (Psittacus erithacus), and Eclectus parrots (Eclectus roratus). The lesion is characterized by an annular constriction around one or multiple toes. In young birds a tight band of scar tissue usually causes the constriction. If not treated, this lesion will lead to avascular necrosis distal to the constriction.
Explore the lesion for the presence of a foreign body such as fibrous material, and debride the annular ring. Make two longitudinal incisions through the annular lesion on the lateral and medial aspect of the toe to relieve the pressure at the constricted site and allow proper circulation to the affected toe. Bandage the toe and monitor daily. Warm soaks with diluted povidone-iodine or chlorhexidine will reduce swelling and prevent infection.
Suspect aspiration pneumonia in chicks presented with a history of intermittent dyspnea and recurrent respiratory infections. Chicks near weaning are most commonly presented with aspiration because they tend to resist feeding. Severe cases die shortly after aspiration, while inhalation of a small amount of formula may be associated with a “cough”-like sound after feeding. Provide supportive care and begin antimicrobial therapy. Nebulization will hasten the clearance of the foreign material from the respiratory system. In some cases, signs recur after the discontinuation of treatment. These chronic cases may have small granulomas on the lung surface and in the air sacs, which may be identified via endoscopy of the air sacs and lungs. Biopsy these lesions to differentiate foreign body granulomas from fungal plaques.
Stunting is commonly seen during the first month of life and may be associated with poor husbandry practices or an underlying infection. Stunting may be characterized by poor growth rate, failure to thrive and low body weight, and thin limbs. The head is large relative to body size and feather growth may be delayed or abnormal. Delayed eye and ear opening are observed in some cases. Eye slits may open dorsal to the horizontal midline of the orbit. Some stunted chicks appear healthy but have an abnormal body weight for their age and they gain weight at a slower rate. If caught early, correction of the underlying problem(s) may reverse stunting.
Unretracted yolk sac
Yolk serves as a source of nutrients and maternal antibodies for the first few days post-hatch. The yolk sac is normally internalized prior to hatch, but incubation problems such as high temperature and/or infection may lead to an unretracted yolk sac.
Chicks with unretracted yolk sacs usually present with an open umbilicus and variable amounts of exposed yolk or umbilical vessel. Collect swabs of the umbilical area for culture, and clean the umbilicus with a mild disinfectant. Then place the chick on a clean surface in the hatcher for a few hours. If the yolk fails to internalize, which is often the case, remove the sac by ligating as close to the umbilicus as possible. Close the umbilicus with fine suture material.