Anatomy: The egg tooth is a dorsal process on the beak, which aids hatching in chicks and disappears soon after hatching. The choana is a cleft in the palate through which the oral and nasal cavities communicate. The cornified keratin layer of the upper beak grows from the dermis which covers the premaxilla. There is a vascular layer between the ramphotheca, the horny covering of the beak, and the dermis. The ramphotheca grows in sheets away from the dermis in a cranioventral plain
Pathologic growth: The growth rate of the beak varies with the various anatomical surfaces as well as the normal wear resulting from demands placed upon the specific growth areas. Normal beak function will chip off the outermost layers as it approaches the top of the beak. It is not clearly understood what controls beak growth rate. Complete replacement of the ramphotheca needs about 6 months. It is very important to know physiological differences in form, length and function of beaks in different species.
Psittacine Beak and Feather Disease (PBFD): In some cases there can be found abnormal growth and degeneration of the epidermis and stratum corneum of the beak. Clinical changes of the beak and oral mucosa of PBFD positive birds are characterizes by progressive elongation, transverse or longitudinal fractures, palatine necrosis and oral ulceration. Necrosis of the upper beak progresses proximally to the palatine area, and may involve the premaxilla in severe cases. The distal end of the lower beak is less severely involved.
Male aggression: Especially in cockatoos the hen is suddenly attack by the male during normal breeding.
Injured beaks, fractures: Acrylic beak repair or wire reinforcement can be performed, however there has been different success with use of these products in beak fractures beyond the germinal layer. In this cases, several applications of the acrylic can support and splint the injury for the time period required by the bird to adjust its eating habits.
Knemidokoptes mite infection: These mites can produce severe damage to the beak especially in budgerigars.
Mycotic infections: Infections of the beak are often in connection with airsacculitis but also solitaire on the beak.
PBFD: see beak.
Candidiasis: Avian candidiasis is a mycotic disease primarily involving the upper alimentary tract. The most common organism isolated is Candida albicans. Certain conditions favor pathogenic overgrowth of Candida. Predisposing factors include prolonged antibiotic therapy, malnutrition and poor sanitation. Young birds are more susceptible. A diagnosis of candidiasis cannot be made on laboratory culture alone, since the organisms can be normal inhabitants of the avian alimentary tract. The degree of mucosal involvement varies from mild white streaking to severe diphtheric membrane formation.
Pox: The diphtheroid form of the disease have the form of papules, which are covered by fibrinous exudate that later becomes grey to brown and caseous. Confluence of multiple foci can form large areas of altered mucosal surface. These exudates cling closely to the surface and cannot be removed without subsequent bleeding or tissue loss, because the whole mucosa is involved in the disease process. Bacterial and fungal superinfection can alter the typical lesions.
Trichomoniasis: Trichomonas can be a difficult parasite to diagnose in psittacine birds. Especially in the early stage of disease a wet mount exam is a low yield test. The clinical signs are vomiting, weight loss, diarrhea and death. Caseous plaques, very similar to pox are the dominant findings. In suspected cases metronidazole may be clinically indicated even without a positive identification of trichomonads.
Internal Papillomatous Disease: Oropharyngeal and esophageal lesions may be manifested variously by dysphagia, regurgitation of recent ingesta, anorexia and progressive weight loss. Therapy using human interferon has been used.
Sublingual foreign bodies: Oral surgery for the removal of sublingual foreign bodies can cause extensive hemorrhage. Therefore radiosurgery should be employed for this procedure.
Vitamin A deficiency: Relative early cases of vitamin A deficiency may manifest as oral mucous membranes that are beginning to undergo squamous metaplasia.
Tumors: different kind of tumors can be found within the oral cavity. Surgical removal has to be performed.
Aspergillosis: Aspergillus is a ubiquitous organism, and birds are continuously exposed to environmental spores. The fungal agent becomes pathogenic only under certain conditions. Predisposing factors include immunosuppression, malnutrition, and unhygienic environmental conditions. Although the lungs and air sacs are the primary organs affected by Aspergillus sp., the mouth and upper gastrointestinal tract are sometimes involved. The diagnosis of aspergillosis can not be made on laboratory culture alone, since the organism can be found also in the oral cavity of healthy birds, especially after ingestion of contaminated food.
Foreign bodies: Foreign bodies can be located not only in the tongue, but also around or sublingual. The removal can cause extensive hemorrhage in birds, therefore radiosurgery should be employed.
Internal Papillomatous Disease: see oral cavity
Vitamin A Deficiency: Advanced oral lesions may involve glands that are entirely converted to squamous epithelium with keratin material. Although these are often called abscesses, if they are not secondarily infected, these are essentially keratin cysts.
Vitamin A Deficiency: see tongue
Aspergillosis: see oral cavity
Pharyngitis: Inflammation due to bacterial infections can sometimes be seen especially after feeding cold food.
Foreign bodies: Especially in young psittacines feeding tubes can be swallowed by the baby bids. In wild birds fishing hooks can sometimes be found in the esophagus.
Candidiasis: see oral cavity. Frequently the crop mucosal surface is coated with a catarrhal to mucoid exudate. The disease is a frequent cause of crop impaction and death in baby psittacines. In older birds it can cause delayed crop emptying and malnutrition.
Trichomoniasis: see oral cavity.
Crop stasis: Crop or esophageal lacerations, scald fistulas, infection of the crop, fibrous food impaction, athony caused by overstretching or foreign bodies may present as crop stasis and can be differentiated by transillumination, insufflation, palpation and,/or endoscopy.
Crop stasis in neonates: If stasis is suspected in a baby bird the crop should be gently palpated to identify foreign objects or food masses. Dehydration, inadequate liquid in the food, change in the amount of food fed, low environmental temperature or generalized infection are some causes of crop stasis in neonates. Regardless of the cause, a bird with crop stasis should not be feed until the condition is corrected. In many cases the problem can be solved by giving 2-15 ml of warm water and gently massaging the crop to break down impacted food.
Sour Crop: This may occur if the stasis of the food material has been prolonged. In this case the crop contents must be removed. This can be done with a soft tube or an ingluviotomy. However the clinician is advised to check for proventricular atony.
Fistula of the crop: A draining fistula of the crop is often resulted from being hand fed a formula that was too hot. The site of the injury in the crop is identified, debrided of all devitalized tissue, and sutured with 4-0 vicryl in an inverting single interrupted suture pattern.
Pendulous crop: These are occasionally encountered and can be surgically reduced if necessary.
Foreign bodies: Heavy metal (e.g., lead, feeding tubes) or other foreign bodies have to be removed. Proventriculotomy has to be performed.
Psittacine proventricular dilatation syndrome (PPDS): The so called "wasting" or "neuropathic gastric dilatation" syndrome has been recognised in different psittacine species since 1971. The clinical disease may be manifested by some of the following signs: regurgitation of recent ingesta, passage of intact seed in the droppings if fed a seed diet, progressive weight loss, a variety of central nervous system disturbances, and radiographic evidence of dilation of the proventriculus and/or the ventriculus. Definitive diagnosis of PPDS rests with histological demonstration of characteristic infiltrates of mononuclear cells in intrinsic and extrinsic splanchnic nerves of the muscular tunics of the alimentary tract. Treatment regimes are purely anecdotal and rely solely on the patient's clinical symptomatology.
Petechiae: Paramyxovirus adherent to the vascular endothelium produces local damage and is considered the cause of the frequently observed petechia on the mucosa of the proventriculus.
Proventriculitis due to "Going Light Syndrome": A rod shaped, gram+ bacterium is regularly found in the ulcerated tissues, which is almost as large as fungal hyphae. So far the germ is completely resistant to antibiotics. Diagnosis can be made by direct smears from faecal samples or contrast radiographic findings.
Candidiasis: see oral cavity
Internal Papillomatous Disease: Papillomata of the mucosa of the ventriculus interfere with normal trituration of ingesta and intact seed kernels may thus pass in the droppings. Impaction may result in ventricular and proventricular dilatation and birds so affected exhibit progressive weight loss.
Psittacine proventricular dilatation syndrome (PPDS): see proventriculus.
DUODENUM, JEJUNUM, ILEUM, (CAECUM) RECTUM
Obstipation: Obstipation is rarely seen in birds. It can appear due to abdominal tumors, egg binding or granulomas.
Enteritis, Diarrhea: There are many causes for diarrhea. Malnutrition, bacterial or viral infections, chlamydia infections or gastrointestinal parasites can cause changes in the form of the droppings. Symptomatic therapy has to be performed until the final diagnose is made. General supportive care, like intravenous fluids, is recommended. Depending upon the status of the patient, it may be useful to collect some diagnostic samples before starting therapy, especially for bacterial culture.
Papillomatosis: The clinical examination under anaesthesia reveals a mass protruding from the vent which is attached to the cloacal wall as well as around the rectal opening. The history of cloacal papillomas is as a rule that of a recurrent "cloacal prolapse" over several month. Venereal transmission of the disease between members of a mated pair is frequently suggested, but has not been proven.
Cloacal prolapse: The gross clinical differentiation of cloacal tissue protrusions, and thus the appropriate therapy, lies primarily in the texture of the protruding tissue. A prolapsed cloaca resulting from sphincter problems, nerve interruption, chronic irritation of the rectum, or tenesmus has the appearance of smooth glistening epithelium. A more complete physical examination differentiates a prolapsed cloaca from a prolapsed uterus or vagina resulting from egg laying problems, or from cloacal papillomatosis. A prolapsed cloaca is potentially serious as it may cause severe constipation and retention toxemia. Acute cloacal prolapses frequently respond to manual reduction and the placement of two simple interrupted sutures.
Hyperparathyroidism in African Grey Parrots: Several etiologies have been proposed for the hypocalcemia syndrome in African Grey Parrots including hypoproteinemia and secondary nutritional hyperparathyroidism. Hypoalbuminemia can cause an apparent hypocalcemia because 30% of the calcium in plasma is bound to albumin. While this bound calcium is not metabolically active, it is nonetheless detected in routine assays for total blood calcium levels. Research with African Grey Parrots has shown that calcium concentrations are significantly affected by the concentration of albumine, with approximately 14% of the variability described in calcium concentrations attributable to changes in albumin concentrations. Because calcium bound to protein is metabolically inactive, birds with hypocalcemia as a result of low albumin levels will remain clinically normal. Additionally, 90% of the hypocalcemic African Grey Parrots evaluated had total protein values within a normal reference range. Therefore, hypoproteinemia was not considered a factor in the hypocalcemia detected in the African Grey Parrots. Secondary nutritional hyperparathyroidism is common in mammals and other bird species fed a calcium deficient diet. Affected animals have calcium concentrations below reference values with normal plasma phosphate and increased AP activity. In our experience hypocalcemic African Grey Parrots will demonstrate phosphorous elevated and AP within normal reference range. Therefore, we postulate that the hypocalcemic syndrome in African Grey Parrots is not related to secondary nutritional hyperparathyroidism.
Because of the low calcium concentrations (100%), elevated phosphorous concentrations normal AP activities, normal total protein concentrations we postulate that hypocalcemic syndrome in African Grey Parrots occurs because of a dysfunction of PTH. A diet containing low calcium and vitamin D concentrations in combination with high levels of phosphorus contributes to the hypocalcemic syndrome in African Grey Parrots.
Clinical Considerations in African Grey Parrots
In humans, isoflurane has been shown to alter calcium metabolism causing a temporary hypocalcemia.16 One could postulate that a similar change may occur in anesthetized birds. Because of the apparent inability of the parathyroid gland to elevate the blood calcium level of African Grey Parrots with the hypocalcemic syndrome, an isoflurane-induced decrease in blood calcium levels could lead to the death of a patient. During the last three years we have had five African Grey Parrots die unexpectedly under anesthesia in comparison to only one bird of all other species. All five African Grey Parrots were on a poor diet but did not show any clinical signs of hypocalcemia, although four of the five birds had a history of a metabolic calcium problem. At necropsy the parathyroid glands of these birds appeared normal.
It is suggested that calciumb be administered 10-15 minutes prior to anesthesia in African Grey Parrots consuming a calcium deficient diet. Further, the authors recommend that calcium for intravenous injection be available when any African Grey Parrot is anesthetized.
Glucocorticosteroids are frequently used as an initial treatment for "shock". Corticosteroids are known to induce hypocalcemia and therefore should be used with caution in African Grey Parrots.
First aid for seizuring African Grey Parrots
An intramuscular injection of calcium is warranted for a seizuring African Grey Parrot, particularly if the affected bird has a history of consuming a calcium deficient diet. While one could argue that the administration of calcium to a seizuring African Grey Parrot in the absence of a specific diagnosis is questionable, it should be noted that only 5 of 192 African Grey Parrots (2.6%) in this study with clinical changes suggestive of hypocalcemia had a plasma calcium level within the published reference value. Prior to determining that these 5 birds were normocalcemic, all 5 received calcium injections as part of the initial therapy with no detectable adverse effects. Although a diagnosis should be made prior to therapy, the measurement of calcium concentration can take some time and it is often more important to initiate treatment immediately. Plasma calcium concentrations will often stay below normal for up to 24 hours after initiation of treatment. The birds usually clinically recover in that time, so blood samples can be taken a few hours later, when the birds have improved. Care must be taken in interpreting AST and CK activities in these latter cases, as these enzyme values will elevate due to muscle damage from the injection