Toxicosis

Various

Lead, zinc, pesticides, medications

Vomiting, abnormal droppings, lethargy, possible CNS signs

Oral upper GI irritation

Cockatiels, various

Plants (Pothos, Philodendron), various medications, other caustic materials

Lethargy, ptyalism, passive regurgitation of water, erythema of tongue and pharynx

Proventricular dilatation syndrome

Macaws, miniature macaws, African grey parrots, cockatoos, others

Avian bornavirus

Weight loss, vomiting, seeds in feces, possible CNS signs

Bacterial GI infections

Various

Gram-negative bacteria

Vomiting, watery droppings, lethargy

Candidiasis

Cockatiels, lovebirds, others

Candida spp

Regurgitation, crop distention, oropharyngeal and crop lesions

Trichomoniasis

Budgerigars, cockatiels, doves, others

Trichomonas spp

Regurgitation, mouth and crop lesions (white matter), mucus in crop

Ventricular, proventricular, or crop obstruction

Cockatoos, macaws, Eclectus parrots, cockatiels, others

Wood shavings, corncob bedding, other bedding, fibers, foreign bodies, ascarids

Vomiting, depression, weight loss

Proventricular adenocarcinoma

Various

Neoplasm

Vomiting, weight loss, lethargy, severe pain, sudden death

Internal papillomatosis

Amazons, macaws

Psittacine herpesvirus 1

Vomiting, straining to defecate, secondary cloacal and choanal infections

Abdominal mass

Budgerigars

Renal or gonadal mass—usually neoplasia

Weight loss, lameness, vomiting

Behavioral

Various

Courtship behavior

Regurgitation on mirror, owner, toy, or cagemate