Amy B. Worell , in Handbook of Avian Medicine (2nd Edition), 2009
Introduction
Toucans are members of the family of birds Ramphastidae, which is part of the club Piciformes. These colourful and interesting birds are further subdivided into six different genera, encompassing approximately 42 species. An additional division into three general categories, the larger toucans, the smaller toucanettes and the modest, slender aracaris, is also useful for descriptive purposes.
Toucans as a grouping are considered tropical birds, encompassing a range that extends from southern Mexico to Bolivia and northern Argentina. Most species inhabit lowland rain forests, although some of the species can be institute in mountainous regions.
The most prominent and distinguishing feature of the family Ramphastidae is the presence of the large protruding neb. Bills vary in colour from black to brilliant or multicoloured, and are actually quite lightweight, being composed of a thick outer covering of keratin with an intricate inner network of trabeculae. The prominent bill is thought to function in species recognition, in procuring nutrient items that might otherwise be beyond their reach, and maybe in courtship rituals.
Toucans are not normally kept as aviary or pet birds. While in that location are several large collections of ramphastids in the world, and a few birds are maintained as pets, the relative numbers are quite small when compared to captive psittacine species. Toucans that are manus-fed make the best pets/companion birds. Though toucans are unable to talk, these energetic birds are able to vocalize, and produce a variety of interesting sounds. The most mutual species plant in captivity are the toco toucan (Ramphastos toco) and the sulphur-breasted (besides commonly called the keel bill toucan or rainbow beak toucan) (Ramphastos sulfuratus) (Fig. xiv.i).
John M. SykesIV, in Fowler's Zoo and Wild Animal Medicine, Book 8, 2015
Biology
The order Piciformes comprises four families: (one) Indicatoridae (honeyguides); (2) Capitonidae (barbets); (3) Picidae (woodpeckers); and (4) Ramphastidae (toucans, toucanets, aracari). The jacamars (Galbulidae) and puff birds (Bucconidae) are at present considered part of the club Galbuliformes. Galbuliformes and Piciformes have historically been grouped together, as they are both zygodactylous and have similarities in tendon structure. However, the current thought is that zygodactyly has evolved separately in dissimilar taxa (including in Psittaciformes and Cucliformes), then this trait does not imply a close evolutionary human relationship. Galbuliformes species are typically insectivorous, neotropical, perching birds and are not oft kept in captivity.eight
Piciformes species are zygodactylous (digits two and iii point forrard, and digits i and iv betoken astern), accept unique and similar flexor tendon pattern in the leg, take a well-developed sehnenhalter of the tarsometatarsal trochlea, have short incubation times, have altricial (naked and bullheaded) young, are cavity nesters, and lack downwardly feathers as adults.8,sixteen,26 Honeyguides (Indicatoridae; 17 species; x–20 centimeters [cm] long) are relatively small birds from sub-Saharan Africa and south asia. Wax, either in the class of a waxy coating of some insects or from honeybee nests, composes some portion of their diet. Adults have thickened peel, potentially equally a protective mechanism against bee-stings, as they are non immune to this venom. They are breed-parasites, and their hatchlings will kill the host hatchlings. Barbets (Capitonidae; 82 species; 9–33 cm long) are pantropical and may be establish in Asia, Africa, and Central and South Americas. They typically have a large head, brusque neck, and strong bills. Barbets are found primarily in forested areas and generally need a habitat with sufficient dead wood for excavation of nesting and roosting sites, although three species of the Trachyphonus genus nest in cavities in the ground. Woodpeckers (Picidae; 216 species; 8–50 cm long) accept a cosmopolitan distribution (although not plant in Australia or Antarctica). They are institute typically in arboreal habitats such as tropical and temperate forests, simply sure species live in sparsely treed areas, including deserts and rocky hillsides. The Ramphastidae family includes toucans, toucanets, and aracaris (34 species; 34–56 cm long). These birds are neotropical and found only in Central and South Americas. They typically have large brightly colored bills and are oftentimes establish in the woods, although some species are nowadays in woodlands and savannas. They typically nest in existing cavities, so their habitat may be limited by the presence of preexisting nest cavities.viii As honeyguides are not often kept in captivity, the balance of this chapter will focus primarily on toucans and provide bachelor information on barbets and woodpeckers.
Increased hepatic iron storage or fe storage disease (ISD) is a serious condition noted in captive birds specially in some species belonging to families Paradiseadae (birds-of-paradise), Ramphastidae (toucans), and Sturnidae (starlings) (Pavone et al., 2014). Avian species that have been evolved to tolerate relatively depression iron content in their nutrition have very efficient iron absorption and do not downregulate their iron assimilation when body stores are saturated or on feeding of high-iron containing diets (Klasing et al., 2012). Many commercial diets intended for convict birds have been formulated using the nutritional requirements of poultry and are not optimal for the low-atomic number 26 tolerating species. In addition, the utilise of animal byproducts significantly affects the nutritional interactions and bioavailability of iron. Absorption of fe from animal byproducts (heme-based iron sources) may be three times college than that from nonheme products containing equivalent iron concentrations. Thus excessive dietary iron, nutritional interactions increasing the bioavailability and genetically or physiologically regulated increased iron uptake in sensitive species are all contributing factors to this condition (Cork, 2000; Sheppard, 2002). A nutrition containing 50–100 mg/kg iron on a dry affair footing has been recommended for sensitive avian species.
Increasing cellular iron concentrations leads to lysosomal injury and release of ionic iron, causing oxidative harm to membranes and proteins. Liver, heart, and spleen are most unremarkably affected. Clinically, dyspnea, abdominal distension, weight loss, and low are major signs. Fibrotic changes in the liver affect its role, unremarkably leading to ascites, hypoalbuminemia, and icteric symptoms. The accumulation of hemosiderin in the lysosome of ISD-susceptible species is a common finding in birds (Cork, 2000; Klasing et al., 2012).
Diagnosis is by radiography (enlargement of liver, center, and spleen), superlative in liver enzymes and transferrin concentrations. A liver biopsy might assist in antemortem diagnosis. To care for the status, chelation with deferiprone (75 mg/kg, PO, once daily for 90 days) (Sandmeier et al., 2012), CaEDTA and BAL have been utilized. Prophylactically, testing the iron content of the ingredients, choosing ingredients with low bioavailability of fe and feeding a depression-iron diet with natural chelators such every bit tannins, phytates and fiber might be useful.
Andrés Montesinos , ... David Sanchez-Migallon Guzman , in Avian Medicine (Third Edition), 2016
Iron Storage Disease
Iron storage disease is a common problem in many captive avian species, including mynahs and starlings (Sturnidae), birds of paradise (Paradisaeidae), bowerbirds (Ptilonorhynchidae), hornbills (Bucerotidae), toucans (Ramphastidae), lorikeets, and other psittacines (Psittacidae). This affliction is defined as an aggregating of excessive amounts of iron in parenchymal cells with resultant cellular damage (Dorrestein and Mete, 2013). The etiology of iron storage disease in avian species remains unknown, but it is speculated that the combination of an adaptation to a natural diet poor in iron and the supply of loftier-fe diets in captivity is the main crusade. Early clinical signs are not very specific, oftentimes just general listlessness and loss of plumage glossiness. In advanced cases, hepatomegaly and ascites causing dyspnea are mutual. A tentative diagnosis can be fabricated based on the clinical signs, radiography and laboratory testing indicating liver illness, and the species of bird affected. Definitive diagnosis is based on a liver biopsy. Liver iron content can be calculated using quantitative image assay, which computes the pct of a Prussian bluish-stained histologic slide that stains positive for iron, by chemical analysis, or by MRI (Sandmeier, 2012). Treatment includes dietary modification to minimalize iron intake by feeding a low-iron diet; reducing dietary vitamin C, such as citrus fruits, which increase the availability of iron in a diet; and by adding tannin-rich or phytate-rich ingredients, such as oak bark tea rather than normal drinking water, which reduce iron availability. Medical handling is based on chelation therapy using the oral iron chelator deferiprone (Sandmeier, 2012). Treatment volition only be successful if started during early stages of the disease, before astringent liver disease develops, and if the patient is monitored long term.
Increased progesterone production (diestrus in female)
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Pancreatitis
•
Drugs (encounter later)
•
Hyperthyroidism
•
Moribund animals
•
Birds
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Hyperglycemia is generally defined by blood glucose concentrations exceeding 500 mg/dL.
○
Hyperglycemia most frequently results from catecholamine release from stress, glucocorticosteroid excess from administration of corticosteroids, and diabetes mellitus.
○
Exertion, excitement, and extreme temperatures stimulate the release of catecholamines, resulting in a mild to moderate increment in the blood glucose concentration. Stress hyperglycemia tin occasionally produce a strong positive on urine glucose dipstick, similar to diabetes mellitus.
○
Excess glucocorticosteroids unremarkably crusade a mild to moderate increase in the blood glucose concentration (≤600 mg/dL) in birds.
○
Concentrations greater than 700 mg/dL are suggestive of diabetes mellitus in birds.
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The pathophysiology of diabetes mellitus in birds is variable, however, and appears to be associated with excess glucagon in the presence of hyperglycemia. In psittacine birds, pancreatitis and pancreatic islet prison cell tumors are known causes. In some species (eastward.k., tucans [Ramphastidae]), diabetes occurs commonly and may be related to diets rich in fruits. Budgerigars and cockatiels are predisposed to diabetes associated with hepatic lipidosis. Birds suffering from diabetes mellitus demonstrate polyuria and urinary glucose concentrations exceeding i mg/dL.
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Reproductively agile cockatiel hens can present with "pseudodiabetes." Plasma glucose levels are elevated only remain nether 1000 mg/dL. The cause appears to exist reduced pancreatic function from inflammation associated with yolk peritonitis.
•
Reptiles
○
The normal blood glucose concentration of most reptiles ranges between lx and 100 mg/dL, but this is bailiwick to marked physiologic variation.
○
The most common cause of hyperglycemia is iatrogenic commitment of excessive glucose.
○
Although a persistent, marked hyperglycemia and glucosuria are suggestive of diabetes mellitus, the disorder is rarely observed in reptiles.
○
Hyperglycemia as well occurs with glucocorticosteroid excess.
•
Ferrets
○
Hyperglycemia most often is transient and due to postprandial increases.
○
Glucocorticoid backlog (e.thousand., chronic stress, exogenous corticoids, hyperadrenocorticism) produces mild elevations in glucose concentration (150 to 200 mg/dL).
○
Stress-induced catecholamine release tin can consequence in higher elevations of glucose (200 to 300 mg/dL) and simulates diabetes mellitus.
○
Diabetes mellitus is relatively rare in ferrets and near often is iatrogenic and associated with surgical removal of pancreatic insulin-secreting neoplasms, or may be associated with apply of drugs such as megestrol acetate. Glucose concentrations are greater than 400 mg/dL and frequently are greater than 1000 mg/dL.
•
Rabbits
○
Hyperglycemia is a relatively mutual finding in rabbits and tin can exist accompanied by glycosuria.
○
Stress-induced catecholamine release is believed to be the virtually common crusade. Handling pet rabbits or warm temperatures upshot in increased blood glucose.
○
Glucocorticoid backlog (e.1000., stress induced, exogenous corticoids, hyperadrenocorticism) is also possible.
○
Hyperglycemia is associated with astringent gastrointestinal distress ranging from astute obstruction to chronic stasis.
○
Diabetes mellitus is rarely a cause of hyperglycemia in rabbits and is rarely diagnosed in pet rabbits. Rare hereditary diabetes occurs in some populations. Herbivorous animals withstand the absence of insulin more readily than carnivorous ones. Direction of hyperglycemia in herbivorous animals is washed via diet modification.
Complete claret count (CBC) frequently shows a mild nonregenerative anemia and balmy leukocytosis or leukopenia. CBC helps to rule out inflammatory hepatopathies.
•
Clinical pathologic test should target and evaluate recent hepatocellular damage, hepatic function, lipid metabolism, and electrolytes.
•
Aspartate aminotransferase (AST): high sensitivity but low specificity should always exist interpreted with creatine kinase (CK) values. Plasma activities may exist normal in very advanced cases and are not consistently increased in hepatic lipidosis.
•
Glutamate dehydrogenase (GLDH): mitochondrial enzyme, low sensitivity but loftier specificity, authentic elevation in cases of severe hepatocellular damage
•
Bile acids: loftier sensitivity and loftier specificity, test hepatic function, moderate to high elevation
•
Full protein (TP), albumin, coagulation factors, uric acrid: decreased with impairment of hepatic product
•
Hypoglycemia may exist seen because of impaired gluconeogenesis, starvation, or chronic disease; peak in cases of diabetes mellitus
•
Lipemic serum and hyperlipidemia are mutual with meridian in triglycerides and cholesterol due to impaired lipid metabolism. Lipemic serum tin can strongly interfere with some biochemical tests.
Hepatic Lipidosis
Severe hypercholesterolemia in a bird. This can frequently be seen in birds on a loftier-fat diet.
(Photograph courtesy Jörg Mayer, The Academy of Georgia, Athens.)
Hepatic Lipidosis
Severely lipemic serum from a cockatiel diagnosed with hepatic lipidosis; such lipemia interferes strongly with biochemistry.
(Courtesy Hugues Beaufrère and Clinique Vétérinaire Brasseur.)
•
Hypokalemia could also be present if the bird has regurgitated, has vomited, or is polyuric.
Advanced or Confirmatory Testing
•
Imaging
○
Radiographs often reveal an enlarged liver with pinch of coelomic air sacs and concomitant overinflation of axillary diverticuli of interclavicular air sacs. Ascites may be nowadays merely is rarely important without concurrent heart illness. Cardiomegaly should be ruled out.
○
Ultrasonographic examination of the liver in affected birds shows an enlarged liver with rounded margins and lengthened amending of parenchyma, which is hyperechoic. Ascites may be confirmed as well. Ultrasound examination is especially useful to rule out liver congestion, in which biopsy could lead to a fatal hemorrhage.
○
Endoscopy allows visualization of the liver via a lateral arroyo, through entry into the ventral hepatic peritoneal cavity from the left or right caudal thoracic air sacs, or by a direct approach, via the ventral midline. Livers exhibiting lipidosis are enlarged with pale or mottled yellowish parenchyma and rounded margins.
•
Histopathologic exam
○
Definitive diagnosis of hepatic lipidosis requires a liver biopsy that may exist taken using endoscopy, ultrasound, or surgery. Histologically, hepatic lipidosis is characterized by vacuolation and degeneration of hepatocytes. A prognosis may exist determined past assessing the degree of degeneration, vacuolation, and inflammation present in the sample.
○
Birds with severe hepatic lipidosis are in metabolic crisis, and anesthesia for collection of a liver biopsy is inappropriate until the patient is stabilized.
Matti Salo , ... Risto Kalliola , in Diagnosing Wild Species Harvest, 2013
Emerging Environmental Awareness
'You shouldn't shoot toucans here near the business firm', grunted Benjamín, a man in his 50s, to the young boys who had accompanied him on a long, but not so successful, hunting expedition. Although they had been camping out in the most remote parts of the customs'southward hunting grounds where wildlife is abundant, their hunting luck had not been every bit good as expected. While returning, about back dwelling again, the boys had encountered a band of toucans fluttering from co-operative to branch through the awning in search of fruits, and they had shot a couple of them. Toucans (Ramphastidae) take huge curved bills (Figure 4.4), and the larger species weigh nearly 600
g on average, just barely plenty to make the bird worth the cost of a shotgun shell. The taste of soup made with smoked toucan is lovely, however, and as a bonus, its plumage in blackness, white, red, and yellowish was the preferred raw fabric for making plume crowns. Benjamín, who had walked a couple of hundred metres earlier the boys, even so disapproved. 'I too saw the toucans, simply I didn't shoot them,' he said, 'because I similar to hear their song near my house. The song of toucans brand yous feel happy. Toucans you should hunt far away, not near the house!'
Effigy 4.4. A white-throated toucan (Ramphastos tucanus).
Photo: Eriberto Gualinga.
During the class of the 1990s, many people in Sarayaku became aware of the fact that wild animals resources were dwindling. However, doing something about it was anything but easy. Avoiding shooting small birds with a beautiful song near your own house was, of course, a commendable initiative, merely effectively tackling the whole problem was much more challenging.
Many people actually saw wild animals depletion equally something inevitable. The only alternative, many idea, would be to end eating wild meat and instead eat domestic animals or industrial food. And this was not highly-seasoned. Although they realised that one day there may really non be any other alternative, the people wanted to continue hunting freely equally long as possible. Equally one human put it: 'Allow the states kickoff hunt all the animals, and then afterwards, when there are no animals left, we can start to enhance animals instead'. The idea to restrict hunting, only not altogether prohibit information technology, in lodge to manage the resources base in a sustainable way, was alien to near people – although not to all. Marlon, for case, a teenage boy studying the final twelvemonth in the newly founded upper secondary school of Sarayaku, fabricated his graduation thesis about hunting. Marlon proposed that the community could set up aside a wild fauna reserve where hunting would exist prohibited birthday. This, he thought, would secure the survival of wildlife populations in spite of hunting standing outside the reserve. Marlon would subsequently go role of a new generation of customs leaders that emerged in the belatedly 1990s who had much more than basic literacy. They often were fluent Spanish speakers who were well informed most current issues on the national and international political calendar. Having reached the primordial objective of securing the customs's country rights, the focus of the community organisation changed from 1992 and onwards. It became more than oriented towards regulating internal affairs and promoting community development. In practice, information technology was becoming a legitimate local government. All important decisions were made in large customs assemblies where all community members had the right, as well equally a social duty, to participate. A four-day assembly was organised to codify through consensus a set up of rules to regulate life in the community. The participants were divided into various working groups; the group in charge of natural resources proposed a long listing of drastic measures, including restrictions on hunting – most of which received applause and blessing in the terminal plenary session. The next mean solar day, all the same, life continued every bit earlier. The children were hungry and the food supplies were empty afterward iv days of sitting still, so many went out to chase. The community lacked even so capacity for enforcement of the rules it had prepare itself.
Sven Hammer , ... Vijaya Baskar , in Avian Medicine (Tertiary Edition), 2016
The Nutrient
Food safety and hygiene are crucial to avian neonates. Food labels (stickers or tags in fruits) should be removed before food preparation to prevent abdominal foreign body obstruction. Information technology is of import to annotation that nutrient items that are safe for i species tin can be unsafe for others. For example, ordinary chicken pellets can cause hemochromatosis (iron storage disease) in some species such as ramphastidae (e.g., toucans) if dietary levels exceed their atomic number 26 requirement of 150 mg/kg a mean solar day (Cornelissen and Ritchie, 1994). Utensils used to prepare meat, fish, or mice (including pinkies) must non be used for cutting vegetables and fruits, to forbid bacterial cross-contamination. For effective cleaning of utensils, oil and biofilm that protect microbes from disinfectants must be removed past using products for deep cleaning such as F919 (Wellness and Hygiene, South Africa). Washing fruits and vegetables to remove soil contaminants can forbid the occurrence of bacterial enteritis and toxicities later ingestion of trace agricultural chemicals.
Sensory evaluation of food items, such every bit inspecting pellets for molds and smelling the baby food for rancidity, tin eliminate the occurrence of aflatoxicosis and fat acrid deficiencies. In addition to fibrous plant material or seeds, growing neonates should be offered dust textile (a dish of coarse sand) to help in breaking down the hard nutrient material into digestible products. It is important to recognize the danger of improper thawing methods. Thawing fish, meat, and whole-animal diets, inclusive of mice and pinkies, at room temperature can significantly increase microbial contamination. Thawing meat or fish by soaking can result in pale meat, depleted of atomic number 26 and water-soluble vitamins. The presence of thiaminase in fish diets, which can lead to hypovitaminosis B1 in neonatal piscivores, should not be overlooked. Cleanliness and sanitation of the common cold storage facility and equipment are essential. Refrigerators and freezers for nutrient storage must non be used to comprise unnecessary items such equally carcasses or eggs for postmortem. Sharing hand-feeding utensils between neonates should be avoided at all times.
Food presentation and the manner of feeding babe formula should be considered. Babe formula with substandard temperature (< 40° C) tin can event in slow crop emptying. Heating of nutrient using microwave ovens should be carried out with extreme caution (encounter afterward). For smaller psittacine species (due east.g., lories, lorikeets, and conures), mixing the formula to accomplish a completely homogenous mix can forbid slow crop elimination, impaction, and indigestion. In addition, aspiration can be prevented in these neonates through gradual pressing of the plunger of the feeding syringe when the esophageal opening is naturally small-scale (Fig. 15-55). Most importantly, the hand feeder must synchronize with the gaping reflex, ensuring gradual injection of food into the esophageal opening to preclude aspiration. It is wise not to feed a neonate if gaping reflex is absent, which ordinarily indicates absence of hunger. Other factors that can suppress the gaping reflex include fearfulness, stress from dissonance, and disturbance. For highly diluted diets (east.g., egg-based liquid diets), the formula should be delivered slowly at the side of the pecker. It is also recommended to agree the caput of the neonate above the level of its shoulder until the baby formula moves down into the crop or below the level in the thoracic level in species without crop. When delivering the food, it is advisable to remove air pockets and bubbles from the syringe to forestall aerophagia. Overzealous provision of nutrient to a gaping neonate tin can be life-threatening.
Chitin is indigestible to mitt-reared passerine neonates, and excessive amounts of insect diet given in the very early stages of evolution can lead to gastrointestinal impaction and even decease. When feeding insectivorous neonates (e.m., starlings, mynahs), early larval stages of insects (e.g., white mealworms) with minimal chitin material should be fed during the early on stages of manus-rearing (Fig. xv-56). For further data on diets and feeding strategies for neonates, the reader is referred to Chapter 3.
In Clinical Veterinarian Advisor: Birds and Exotic Pets, 2013
Etiology and Pathophysiology
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Hepatic lipidosis: known too as fatty liver syndrome, occurs if the deposition of fat inside hepatocytes, due to an increased use of fat past liver. Dietary causes are the main etiology, such as insectivorous raptors (e.yard., merlins) fed on pinkies or psittacines fed on oily seeds. Other causes of lipidosis include mobilization of fatty reserves in prolonged periods of anorexia or in females during egg-laying as a upshot of estrogen-controlled lipogenesis.
•
Visceral gout: accumulation of uric acid crystals in different organs, including the liver; usually the course of the illness is very fast, and animals tend to die before signs of liver failure are noted.
•
Amyloidosis: secondary amyloidosis is seen in chronic infection situations or in prolonged stress situations; continuous degradation of proteins in the hepatic parenchyma causes necrosis by pressure.
•
Lipofuscinosis: lipofuscin is a pigment that accumulates in hepatocytes secondary to diseases in which an increase in biological oxidation is present. Vitamin Due east deficiency may be causative because of its antioxidant role.
•
Nutritional
○
Microhepatica: although small livers are a common finding in psittacines, reduced size of the liver tin be linked with fibrosis secondary to diet-rich seeds.
○
Hemochromatosis: although included as nutritional disease, the cause of this disease remains unclear; several authors have reported that the cause of the disease is nutritional; other studies suggest genetic causes. Hemochromatosis is described equally atomic number 26 accumulation associated with deleterious effects for the body. This condition is described in birds from the post-obit families: Sturnidae, Paradisaeidae, Bucerotidae, and Ramphastidae.
○
Hypervitaminosis D3: due to oral oversupplementation; this condition tin can crusade mineralization of soft tissues, including the liver.
•
Toxins: several drugs, including antibiotics and antifungal drugs, are considered potentially hepatotoxic for birds; therefore, liver part should be assessed regularly in birds exposed to these drugs for prolonged periods, in the same way that some plants and fruits like avocado, or environmental substances like lead and zinc, are reported to be hepatotoxic.
•
Infectious diseases: several parasitic, bacterial, and viral diseases can cause liver failure
○
Protozoa
▪
Atoxoplasma: generally affects young birds, betwixt 2 and ix months onetime
▪
Toxoplasma: tin crusade hepatomegaly
▪
Sarcocystis: Erstwhile World avian species are more sensitive to this parasite, which, on superlative of pulmonary lesions, causes hepatomegaly and splenomegaly
▪
Cryptosporidium: affects epithelial cells in biliary tract
▪
Plasmodium: common cause of hepatosplenomegaly; certain species of the orders Strigiformes and Sphenisciformes are more than susceptible
▪
Leucocytozoon: tin can cause necrosis past its presence; ordinarily no inflammatory reaction is associated
▪
Haemoproteus: schizonts can be plant in the liver, although generally this condition is nonpathogenic
▪
Histomonas: tin can cause severe local hepatocellular necrosis; has been reported commonly in poultry; known every bit blackhead.
▪
Trichomonas: although this pathogenic issue is express to the gastrointestinal tract, if it is not treated, information technology tin invade the liver, causing necrosis
○
Trematodes: some species from the family Dicrocoelidae have been reported in birds, causing liver damage equally the result of migration, pressure necrosis, biliary stasis, and hyperplasia of bile ducts
○
Nematodes: different abdominal nematodes can penetrate abdominal mucosa and travel to the liver, causing a major inflammatory reaction with secondary fibrosis
○
Bacteria: several leaner have been associated with liver failure as main agents or secondary to other conditions such as viral disease
▪
Gram-positive bacteria: usually cause hepatitis secondary to septicemia or with infection of the lungs or air sacs due to proximity to the liver. Staphylococcus, Streptococcus, and Clostridium are mutual Gram-positive bacteria isolated in abscess in hepatic parenchyma
▪
Gram-negative bacteria: Salmonella, Escherichia coli, Pseudomonas, and Yersinia are isolated frequently, causing multifocal necrosis and a major inflammatory response.
▪
Mycobacterium: usually with chronic presentation, endoscopy may reveal areas of necrosis and caseous material in liver parenchyma
▪
Chlamydophila: very common in psittacines; causes different degrees of hepatic necrosis; by and large respiratory or gastrointestinal signs are observed.
▪
Bacillus piliformis: very rare in birds, as other bacteria tend to crusade necrosis of the liver. Considering Chlamydophila is an obligate intracellular bacterium that tin exist seen in hepatocytes, cytoplasm is accompanied past a stiff inflammatory response.
○
Fungal: Aspergillus is the virtually common fungus isolated in cases of liver failure, although other fungi, such every bit Candida, have been isolated. Although Aspergillus is non a common primary pathogen in the liver, the aflatoxins that the fungus produces are highly hepatotoxic.
○
Virus
▪
Herpesvirus: unremarkably the presentation is peracute or acute, making diagnosis and handling very difficult. In some situations, isolation of viral antigens from cloacal mucosa is possible; the presence of cloacal papillomas may propose that the liver is affected by herpesvirus.
▪
Polyomavirus: very unremarkably reported in psittacines, affecting young birds, younger than 12 months of age
▪
Adenovirus: has been reported every bit a cause of hepatitis, mainly in psittacines and poultry, although cases in waterfowl, raptors, and pigeons have been described
▪
Circovirus: liver damage is normally present in young birds, which are more than susceptible, causing severe necrosis
▪
Reovirus: reported in psittacines every bit astute systemic disease, causing focal hepatic necrosis with minimal inflammation
▪
Hepadnavirus: causes hepatitis in ducks
•
Neoplasia: bile duct carcinoma or adenoma, lymphoid leukosis, fibrosarcoma, hemangioma
The Pathology of Comparative Animal Models of Man Haemochromatosis
R. Klopfleisch , P. Olias , in Journal of Comparative Pathology, 2012
Fe Storage in Birds: Malnutrition or Genetic Background?
Several species of captive birds are reported to develop an fe overload syndrome. The disease is reported commonly in Indian mynah birds (Sturnidae) (Fig. 10) and toucans (Ramphastidae) (Fig. xi) and to a lesser extent in hornbills (Bucerotidae), birds of paradise (Paradisaeidae), flamingos (Phoenicopterus spp.), starlings (Sturnus vulgaris; Sturnidae), tanagers (Thraupidae) and some psittacines (Randell et al., 1981; Gosselin and Kramer, 1983; Wadsworth et al., 1983; Taylor, 1984; Lowenstine, 1986; Kincaid and Stoskopf, 1987; Ward et al., 1991; Cork, 2000; W et al., 2001). Information technology is hypothesized that both genetics and nutritional inadequacy can contribute to disease evolution in captivity, since at that place is a loftier correlation with the use of commercially formulated food. In full general, frugivorous and insectivorous species are affected more commonly. Some bird families, peculiarly Sturnidae, Ramphastidae and Paradisaeidae, may exist predisposed due to a specific sensitivity to dietary atomic number 26 uptake (Lowenstine and Munson, 1999). The pathophysiology of avian atomic number 26 storage syndromes remains obscure; however, Mete et al. (2001, 2003, 2005) have shown for mynah birds that the abdominal fe uptake and transfer into circulation is increased compared with species that are not susceptible. Therefore, at least in some avian species, the charge per unit of iron load appears to be influenced past species-specific physiological mechanisms.
Fig. 10. Mynah bird, liver. (A) Nearly all hepatocytes incorporate large amounts of haemosiderin. HE. Bar, 300 μm. (B) Turnbull blue stain of a serial section. Bar, 300 μm.
Fig. 11. Toucan, liver. (A) Marked iron aggregating in hepatocytes without obvious signs of hepatocellular degeneration or fibrosis. HE. Bar, 200 μm. (B) Turnbull blue stain of a series section. Bar, 200 μm.
Clinically, birds with atomic number 26 storage disease have dyspnoea, center failure, intestinal swelling, ascites and weight loss (Cork, 2000). Organs afflicted most usually by iron overload are the liver, spleen and center muscle. Electron microscopy of hepatocytes of mynah birds revealed iron accumulation in membrane-bound lysosomal structures and costless as ferritin or larger haemosiderin aggregates in the cytosol (Lowenstine and Petrak, 1980). Brusk-term accumulation of fe in the liver is a common secondary finding and is often associated with malignant and infectious diseases in well-nigh species. This must be differentiated from primary fe overload syndrome (Cork et al., 1995), which can be challenging as jail cell degeneration and fibrosis is uncommon in birds with primary iron overload (Wadsworth et al., 1983).
Iron overload syndrome of captive birds appears to be strictly associated with nutrition. The severity of storage is proportional to the period of time that birds have been held in captivity (Taylor, 1984; Lowenstine, 1986). This supports the hypothesis that some species may have maximized their efficiency for iron uptake from low iron-content nutrient in their natural habitat and cannot adapt to higher food iron content in captivity (Otten et al., 2001). Experimental studies of mynah birds and starlings suggest that the intestinal absorption of iron in birds is non as tightly regulated as information technology is in mammals and that susceptible species are unable fairly to downwardly-modulate the uptake of iron to foreclose fe storage disease (Ward et al., 1991; Mete et al., 2001, 2003). Mynah birds have greater intestinal uptake of fe compared with chickens and doves. Isolated mynah bird enterocytes showed considerably higher iron uptake compared with chicken enterocytes (Mete et al., 2003). The transporter affinity (Km) was similar for both species, merely a three-fold college uptake rate (Vmax) was plant, suggesting an increase in the number of iron transporters. With natural diets low in iron and high in iron chelators (e.yard. phytates and tannins), some bird species may accept developed physiological mechanisms to absorb dietary fe more efficiently, since complimentary-ranging mynah birds have adapted to a natural low-iron diet consisting mainly of fruits and sometimes of insects, which are low in iron content (Mete et al., 2001).
To elucidate the mechanism of increased intestinal iron uptake, Mete et al. (2005) investigated the mRNA expression of DMT1 and FPN-ane in mynah birds. DMT1 mRNA in the duodenum was expressed almost two-fold higher than in chickens, which are regarded as not-susceptible birds. Moreover, the expression of FPN-1 was higher in all tissues and the magnitude of the divergence reached up to two-, three and a half- and seven-fold in the duodenum, jejunum and ileum, respectively.
Interestingly, some free-ranging birds such as starlings (S. vulgaris) prove seasonal changes in hepatic fe concentration similar to Svalbard reindeer, which can resemble iron overload (Osborn, 1979; Osborn and Immature, 1985). In an experimental written report, starlings fed with radioactive 59Fe showed two to three times college hepatic concentrations of atomic number 26 during the postal service-moult period (Ward et al., 1991). Seasonal variances in hepatic iron concentrations have also been reported in free-ranging female person eider ducks (Somateria mollissima) and mallards (Anas platyrhynchos) (Borch-Iohnsen et al., 1991; Cork et al., 1995). At the end of brooding, female eider ducks, in contrast to the non-breeding period or males, showed an up to 10-fold increase in iron concentration with massive accumulation in hepatocytes and Kupffer cells. No cellular damage was recorded and it is suggested that the periodic accumulation may be a consequence of a combination of factors such every bit an increased iron uptake in the menstruum before egg laying, a concentration issue acquired by reduced liver weight and catabolism of blood and lean body tissue during the laying and brooding periods (Borch-Iohnsen et al., 1991).
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