Presenting problem: Anorexia in Birds

Understanding anorexia in birds

Anorexia is a common problem in the sick patient, and loss of appetite may be the only presenting complaint in the critically ill bird. By the time other signs of illness are apparent, disease is often quite advanced. This means that all reports of poor appetite in the avian patient must be taken very seriously (Fig 1).

Figure 1. The poor appetite of this debilitated double yellow-headed Amazon parrot (Amazona oratrix) must be taken seriously. Photo credit: Jill Murray, RVT.

Anorexia is a non-specific sign of illness with many potential causes. Regardless of the underlying cause of the bird’s poor appetite, anorexia can quickly become a life-threatening problem much as would be seen in a puppy or kitten. Birds have a relatively small body weight and a higher metabolic rate. Even a large bird, like a macaw, typically weighs no more than approximately 1 kg (or 2.2 lbs).

Key points of urgent care

• Rapidly provide nutritional support.Acute malnutrition is associated with acute protein-energy malnutrition (Macintire 2006). The stress of critical illness will accelerate starvation because the animal is in a hypermetabolic state. Energy is stored partially as glycogen in the liver and muscle but primarily as fat. Glycogen reserves of the fasting bird are depleted within a matter of few to several hours depending on the species (Jenkins 1997). Fat is then preferentially metabolized in birds. This in turn is followed by loss of muscle mass and a reduction in heat production, resting metabolism, and body temperature. This may explain why anorectic birds frequently develop a fluffed and ruffled appearance.
• Provide additional supportive care as needed.Offer supplemental heat if the bird is fluffed and ruffled. Carefully monitor body weight and clinical status.

Case management

With the use of an accurate signalment, a detailed history, careful observation, comprehensive physical examination and basic diagnostic testing, the clinician can begin to gather clues that will narrow the differential diagnosis list. While working to achieve a diagnosis, provide nutritional support and additional supportive care.

Signalment

Signalment such as gender, age, and species may provide helpful clues for a diagnosis. See our basic information sheets on the macaw, cockatoo, Amazon parrot, African grey parrot, conure, cockatiel, parakeet, canary, finch, lory and lorikeet, and lovebird for a brief list of medical conditions common in each group.

History

Is the loss of appetite partial or complete? What is the duration of anorexia? Remember that it may be difficult to accurately determine duration of poor appetite, even with a conscientious bird owner, since prey species may pretend to eat. Pet birds may even go so far as to hull seeds and pretend to eat them. So also ask if there has been weight loss since some parrot owners weigh their birds regularly. Obtain a medical history as well as detailed information about husbandry and behavior (Box 1).

See Forms and Questionnaires for our collection of comprehensive history forms.

Physical examination

Careful observation is crucial. When faced with the stress of a strange exam room, most prey species like parrots and songbirds will attempt to appear alert as an instinctive survival adaptation. A 5-10 minute acclimation period provided while the history is being obtained may allow the bird to relax its guard slightly so that other subtle signs of illness may be detected (Box 2).

Perform a comprehensive physical examination whenever possible including a body weight in grams and evaluation of the patient’s body condition. Perform an abbreviated examination when the patient’s clinical condition is not strong enough to handle a complete exam (Box 3). In some instances, observation may suggest the patient is not strong enough to tolerate any evaluation at the moment. Instead the patient should be placed in a warm incubator in a dark, quiet environment.

Differential diagnoses

Anorexia is a non-specific sign of illness and the list of potential differential diagnoses is extremely long. Use signalment, history, careful observation, detailed examination, as well as the results of the minimum database to narrow the differential diagnosis list. Rule out conditions such as infectious disease, neoplasia, and toxicosis. Also consider problems that make access to food challenging such as neurologic deficits, lesions of the oropharynx and beak, as well as musculoskeletal or ophthalmic disease.

Diagnostics

In addition to a detailed history and complete physical examination, that may need to be performed in stages. The minimum database gathered will vary with the circumstances but may include:

• Complete blood count
• Chemistry panel
• Protein electrophoresis
• Survey whole body radiographs
• Fecal parasite testing (optional)

Additional tests that may be performed by an avian veterinarian depending on the clues gathered may include:

• Blood lead and zinc levels
• Serum bile acids
• Serology and/or PCR testing: Chlamydophila psittaci, avian polyomavirus, aspergillosis, psittacine beak and feather disease, avian bornavirus, etc.
• Urinalysis
• Contrast radiography
• Biopsy or fine needle aspiration
• Alternate imaging such as ultrasound or fluoroscopy
• Endoscopy

Therapy

Base additional therapy on diagnostic test results. If diagnostic test results are inconclusive or the patient does not respond to the prescribed therapy in a timely manner, consider referring the patient to an avian specialist.

Conclusion

Anorexia may be the only indication of poor health in the critically ill bird and by the time other clinical signs are apparent disease may be quite advanced. This means that all reports of poor appetite in the avian patient must be taken very seriously. Use signalment, history, examination and the minimum database to narrow the differential diagnosis list. While working to achieve a diagnosis, provide nutritional support and additional supportive care.

References