Obesity in Parrots : Killing with Kindness
Photographs © C J Hall
The problem of obesity is common to all species, and means excessive weight in relation to body size, as a result of fat deposition. It is a complex subject, only partially understood. Hormones, genetics, psychological factors and exercise all play a role.
Further research in obesity prevention and control in our pet parrots is vital. Avian veterinary surgeons whose patients are mainly pet birds find that obesity, and diseases caused by poor diet, make up a very significant part of their workload. Although diseases caused by nutritional deficiencies may be decreasing, this is matched by an increase in obesity related problems.
Common sense would dictate that keeping parrots - which are very active in the wild - in captivity, with limited space and an ad lib supply of food, will result in an overweight bird. Some species are much more prone to the problem than others, for example Budgerigars, Cockatoos and Amazons. Obesity seems less common in Macaws, Conures and Caiques (there are, of course, exceptions).
Parrots on all seed diets are more likely to be obese, owing to the high energy/oil content of their food. Some species, however, thrive on high fat diets, for example Hyacinthine Macaws, their natural diet being based on high fat seeds such as palm nuts. As a result, in young birds of this species, a diet containing up to 25% more fat than is normal for psittacine birds is recommended for optimal growth.
Conversely, Roseate Cockatoos seem to need only to look at a sunflower seed to become overweight. Not all Macaws tolerate high fat diet diets; Red-bellied Macaws need strict calorie restriction. Some of these species differences can be explained by adaptation to habitat.
Many Australian psittacids live in arid, dry areas, where they have to fly great distances to obtain food and water. When food is available, these birds have to make the most of it and their bodies are adapted to conserve nutrients and store fat. Their diet in the wild is largely seed based, and food is often seasonal. In captivity (even in a large aviary) these birds are flying miniscule distances compared to their wild counterparts. Rapid conversion of food to fat then becomes a liability. Other (for example rainforest) species, such as Caiques, have a more abundant year-round food supply as well as a more varied diet, which means they do not convert food to fat so readily.
Of course this is a very simplistic view and there are so many exceptions that the theory provides a partial explanation at best. Amazon parrots are famous for being greedy, and few of this species originate from arid conditions. Some parrots are more sedentary than others and Amazons on their own in captivity are relatively lazy, often being reluctant to fly, while still having large appetites.
Older birds of all species are less active and more obesity prone. Hormonal disorders, such as an under-active thyroid, will lower a bird’s metabolic rate, making it put on weight. In Budgerigars this can be caused by lack of iodine, which causes goitre (a malfunction of the thyroid gland), leading to hypothyroidism (an underactive thyoid), one symptom of which is excessive weight gain. For this reason, an iodised seed mix (such as trill) should be fed, and loose seed mixes (from the pet shop, for example) should be avoided, unless supplemented with tincture of iodine in the water, or iodine blocks. Other parrot species do not seem to be so sensitive to iodine deficiency, so supplying iodine blocks is of no value except as a beak sharpener.
What are the problems associated with obesity
Lipomas: these are benign fatty tumors, literally lumps of fat. They have their own blood supply and are commonly found on the chest, neck and near the vent. Budgerigars and Cockatoos seem to be particularly prone to these growths. In themselves, they are usually harmless, but their presence nearly always indicates an overweight bird. They can become large and heavy enough to prevent flight (thus accelerating weight gain).
If they develop on or near the vent, they can cause infertility (especially in Cockatoos) as they impede proper mating. In Budgerigars they can alter the angle of the vent, resulting in soiling of the tail feathers. If this is severe enough, the vent can become blocked, leading to kidney damage.
Occasionally the lipoma becomes so large it outgrows its blood supply and ulcerates, causing pain and bleeding. Improving the bird’s diet and reducing calorie intake will stop the lipoma(s) growing any larger, but will not cause them to regress. They can be removed surgically, but only after the bird’s weight is reduced and its health restored. Overweight birds are high-risk subjects for anaesthetics. Removing very large lipomas from small birds obviously carries the risk of shock, due to blood loss (just because of the amount of blood contained in the mass).
Fatty liver syndrome: this is a serious threat to your parrot’s health. A combination of overfeeding, with a diet high in saturated fat, together with other factors (vitamin and mineral imbalances, lack of exercise, cholesterol imbalances) results in lipids (fats) being deposited in the liver. The liver may become enlarged (causing breathing problems) - symptoms include diarrhoea and yellow stained urates (the whites), fluid can form in the air sacs, and clotting problems, causing spontaneous bleeding . The disease can progress to liver failure and death. The foie gras produced by force feeding ducks and geese is actually a fatty liver.
As always in avian physiology, the situation is more complicated than it seems. Migratory birds, for example, actually develop a form of fatty liver to store food for their long flight. This is reversible, and essential for survival. The fat is burnt up by exercise. Hen parrots show some degree of fatty change in the liver when they are producing eggs. This is also normal. Treatment of fatty liver involves correcting diet, supplements and keeping the bird feeding (anorexia being a common symptom as the condition progresses). Using thyroid hormones to raise the bird’s metabolic rate may be helpful, as may liver support drugs such as milk thistle and lactulose. Cholesterol lowering drugs are unproven at present.
Atherosclerosis: this is where cholesterol is deposited in blood vessels as plaques. It can be linked to obesity, but also occurs as a result of deficiencies, age, high fat diets and lack of exercise. As in mammals, there is likely to be a link with cholesterol levels. The condition is particularly common in African Grey Parrots and Amazons. Some birds can be very young when affected. The damage caused to the blood vessels, especially the major blood vessels near the heart, can cause sudden death. Milder forms of the disease cause breathing problems, paralysis in one or both legs, blindness and convulsions. Heart failure is a common sequel. Changes in the blood vessels can be seen on x-rays. There is no specific treatment.
Infertlity and egg binding: Fat parrots are less fertile, and the ovarian cycle in hens may be disturbed. Abnormal ovulation can cause egg peritonitis. Fat birds are more likely to become egg bound as excessive fat around and in the walls of the oviduct and cloaca can reduce muscle strength and contractility. Fat parrot hens are more likely to become exhausted while laying.
Hernias: these are frequently associated with obesity. Excessive fat in the abdominal muscles weakens them, and internal fat - with or without liver enlargement - increases the abdominal pressure on these weakened muscles, leading to rupture. Surgical repair, once the bird’s weight is reduced, may be indicated.
Foot problems: Obese birds develop calluses, sores, cracked feet and even infections (in a bird of prey this would be bumble foot - see photo).
Preventing your bird from becoming overweight begins with recording its weight. Use the same scales each time - it is weight change that is important. Sudden weight changes are often the first signs of illness in your pet. Regularly handling your bird and feeling its pectoral area (breast muscle) will give a rough guide. Prominent keel bones and sunken muscle indicate lack of condition, sunken keel bones and bulging pectoral muscles may show early obesity. Fatty folds around the vent and neck are early warning signs. The more exercise the bird has, the more fat it burns. Cages should be as large as possible and not overcrowded with toys, swings etc. Parrots must be encouraged to fly. The first sign of obesity is often reluctance to fly or breathlessness after flight. Once your bird stops flying, weight is piled on even more quickly. It follows that wing clipping is going to accelerate weight gain.
There is no magic diet which will keep your bird slim. Seed-based diets contain more calories, and amounts should be monitored more carefully. Try removing the seed for several hours a day and feeding fruit and pulses instead. This will also encourage more adventurous tastes in your birds. It is essential to use supplements if the diet is mostly seed. Do not over-supplement, seek veterinary advice as to quantity. Birds on pelleted diets are less likely to become obese, but this depends on the manufacturer. Some pellets are simply crushed and reconstituted seeds. Parrots such as Amazons can get fat on anything - restriction is the key here. Human food is good for parrots, the more variety the better, but it is obvious that fatty or fried foods are inadvisable. Avoid chips, crisps etc. Dairy products such as cheese should only be fed sparingly.
Chris Hall qualified at the Royal Veterinary College London in 1986. He subsequently worked at the Blue Cross Hospital in Victoria where he was able to obtain extensive surgical experience, particularly in the fields of orthopaedics and trauma medicine.
In 1988 he became principal of the Acton veterinary surgery. Eventually the exotic caseload at Acton became so great he decided to open a dedicated exotics centre in Sheen in 1995, leaving Acton as a thriving dog and cat practice with its own management.
Chris’s areas of expertise include avian medicine and surgery, but he also has interests in the fields of reptiles and fish. His clients include Harrods in Knightsbridge, Kings Reptile world in Camden, AA Aviaries, the Nottcutts garden centre chain, Maidenhead Aquatics in Syon Park, as well as Battersea Zoo. His caseload can thus vary in a day from short clawed otters, through red tailed catfish to African Hawk Eagles.
Chris Hall is a member of the Association of Avian Veterinary Surgeons, the British Veterinary Zoological Society, the Association of Reptile and Amphibian Veterinary Surgeons and the Fish Veterinary Society. He has written papers for the British Small Animal Veterinary Association on Psittacine diseases. He is the Veterinary Agony Aunt for Parrots magazine.
