News and Research

Birds: Health, disease and physiology



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Social isolation shortens telomeres in African Grey parrots (Psittacus erithacus erithacus).

Parrot lifespan and health likely to be affected by social isolation

Source: Aydinonat D, Penn DJ, Smith S, Moodley Y, Hoelzl F, Knauer F, Schwarzenberger F.
PLoS ONE, 9(4): doi:10.1371/journal.pone.0093839. (2014)

Parrots are often kept alone as pets, though they live in groups in the wild, so social isolation is likely to cause stress in these social creatures. Stress and ageing are linked to a decrease in the length of telomeres, which are the ends of chromosomes. Telomeres help to keep chromosomes stable and control the ageing of cells. Individuals with shorter telomeres tend to be more susceptible to a range of diseases, and their lifespans tend to be shorter.

Forty five captive African Grey parrots were tested for telomere length, to see how this might be affected by social isolation. Twenty six of the parrots were kept alone, and nineteen were kept in pairs. They were between 0.75 and 45 years old. Differences in telomere length were measured by analyzing blood samples.

Telomeres tended to be shorter the older the parrot, and to be shorter in parrots kept alone compared with parrots kept in pairs. Parrots kept alone had telomeres of a similar length to parrots kept in pairs hat were much older. This is evidence that telomere length in parrots is affected by social isolation, and is a marker that indicates that an individual has suffered chronic stress. Previous studies focused on the endocrinological and neurochemical effects of social isolation.

Wild African Grey parrots roost in very large flocks of thousands of birds, and forage in smaller groups of 30 or fewer parrots. They are also monogamous. Captive parrots are often kept alone, and this has been linked to linked to feather plucking, screaming, aggression, fear of anything new (neophobia),and chronic illnesses. Hand-rearing (by humans) also leads to permanent changes in parrot behaviour, some of which can be problematic.

Shorter telomere length did not appear to be linked to current poor health in the parrots studied, though telomere length may have been affected by isolation in the past, as well as in the present. Further research is needed to investigate the link between isolation, health and telomere length in parrots. This study indicates that social isolation is likely to cause long-term physiological and behavioral problems, in African Greys raised with their parents, as well as in parrots raised by hand.

First aid and emergency care for the avian casualty

Helping sick and injured domestic and wild birds

source: Glen Cousquer
In Practice vol 27 no 4, April 2005
starts p190, 12 pages long

Vets often get phone calls about injured birds, and need to provide clear advice and calm the caller, because distress upsets the bird. Some birds can injure the public, and need collection by specialists. Others can be caught with a cloth or net, and put in a dark box with ventilation at the base, so overhead shadows don't overstimulate the bird. First aid may be needed for respiratory distress or bleeding. Vets need to record the location where wild birds are found, so they can later be released there. Some birds, like herons, can stab, others, like falcons, can bite. Birds can be held in a folded towel and hooded if necessary. Domestic birds often suffer from infections, malnutrition and egg binding. Sick birds need their condition stabilised before clinical examination, for example breathing difficulties with oxygen cages and dehydration with fluid therapy. Wild bird casualties tend to be dehydrated, and fluid is essential before solid food. Vets may need to immobilise limbs, and give antibiotic therapy, though intramuscular injections can damage muscles. Birds in shock, such as oiled birds, need darkness, quiet and warmth. Warm water is necessary for crop washing in birds that have been poisoned, and the proventriculus and ventriculus may have to be flushed, if lead shot has to be removed. Oiled birds may need astringents and adsorbents, such as preparations including activated charcoal, to prevent the absorption of poisons from the intestine. Glucose or other nutrients are recommended when birds are not given food.


Shell shock

Egg colour changes in chickens

source: New Scientist vol 207 no 2770, 24 July 2010 p65

Chickens produce white eggs, though some breeds add a brown coating just before they lay. Shells form over some 20 hours in the hen's uterus, with brown pigment secreted in the last three or four hours. The eggshell is porous, with a waterproof cuticle that can be affected by ageing, infection, or stress in the hen. Stress leads to a release of adrenaline, which halts shell formation. This can affect the cuticle, and so pigmentation. Lack of a cuticle can also mean unprotected pigmentation, so colour can rub off. Pigmentation that does not rub off shows a properly formed cuticle, which helps prevent bacteria invading eggs, and eggs with cuticles are safer for humans to eat.

Calcium overload

Dangers of giving chickens too much calcium

source: Darold Stenson
Country Smallholding December 2003 p13

Calcium is important for bones, teeth, and growth, and helps with muscle contraction and blood clotting. Laying hens need calcium supplements, but too much calcium can cause problems, and even kill chickens, through kidney failure. The process is slow, and birds may not become ill for some years. Affected birds may lay fewer eggs, then become less active, and may also limp

Too much calcium in the feed is one cause. Breeder feeds have higher calcium levels than maintenance feeds, and should only be fed during the breeding and laying season, not all year round.. Causes also include feeding crushed oyster shell all year, instead of stone grit, to help with digestion. Chickens should have access to grit all the time, and only be given oyster shell a month or so prior to starting to lay, with the oyster shell withdrawn at the end of the laying season. Breeder feeds, with their higher calcium levels, are designed to boost egg production, and reducing calcium levels may affect production, so chicken keepers may also need to think about whether their birds should have more natural lives, with lower calcium levels, and laying fewer eggs.

Faster, cheaper, sicker

Health problems arising from over-selective breeding of chickens

source: Joyce D'Silva
New Scientist no 2421, November 15 2003 p19

The consumption of chicken broilers worlwide has risen to 49 billion from under 8 billion in the 40 years to 2003, while the time taken to grow chickens to some 2 kilos has dropped to 41 days from almost three months in the three decades to 2003.

Problems can arise in particular from very selective breeding used to produce fast-growing chickens. Compassion in World Farming aims to end this problem through seeking a judicial review of British government policy on selective breeding.

The gene pool of chickens is narrowing. Three companies account for 98% of meat chickens and their descendents world wide. Too-rapid growth can lead to skeletal problems, and as many as 20% of birds may suffer from consequent lameness. Lame chickens choose to eat feed with painkillers, and this helps them to move more normally, according to researchers from the University of Bristol, England. Liver and heart problems are also associated with too-rapid growth. The diets of fast-growing chickens are restricted, when they are not slaughtered at an early age, but instead kept to their breeding age of 20 weeks, since mortality rates are high if these chickens are allowed normal rations. This dietary restriction leaves the chickens chronically hungry. This contravenes a 1998 European Union directive that states that animals should not be farmed of they cannot be kept without health or welfare problems linked to the animals' genotypes.

Beak trimming

Trimming the beaks of poultry can harm their health

source: Victoria Roberts
Country Smallholding November 2002
starts p18, 2 pages long

Trimming the beaks of poultry can cause pain to the birds and prevent their picking up food, so the birds may not grow properly. It was once used as a way to stop poultry damaging one another so that they could be kept in a more confined space. More space per chicken is now seen as a better solution. Free-range poultry keepers tend not to trim beaks. A poultry keeper buying from a supplier should tell them that they do not want chickens with their beaks trimmed. Trimming beaks is mutilation. The beak may have to be re-trimmed if not properly trimmed at first. Calcium supplements do not help birds with trimmed beaks, and could affect egg production.

Birds eye

Small eye pupil in chicken

source: Victoria Roberts
Country Smallholding November 2002

Chickens may suffer from eye disease which results in the pupil of an eye becoming very small. This could be the result of a viral infection. The pupil sometimes recovers, though not always, and affected birds appear to retain some vision. Chickens may be otherwise healthy, but could become targets for bullies in the flock. There is a possibility that the condition could be inherited, so it is best not to use affected hens as breeders.

Incidence and antibiotic resistance of pathogenic Escherichia coli among poultry in Belgium

Avian E.coli and antibiotic resistance common among Belgian poultry

source: F. Vandemaele et al
Veterinary Record vol 151 no 12, September 21 2002
starts p355, 2 pages long

Escherichia coli is also called avian pathogenic E.coli (APEC) when it affects poultry. Infections tend to start in the trachea, spreading to the lungs and then the internal organs. The oviduct may become infected, which affects egg-laying, and the infection can be fatal. The meat of broilers may also show fibrous lesions.

A survey of birds studied at East-Flanders regional laboratory, Belgium, has found that 17.7% of broilers were affected. A sample of dead or diseased egg-layers found a higher rate, of 38.6%. This high rate was because of the type of sample, and the incidence of 17.7% is more accurate. APEC infection was found in 153 of 503 Belgian poultry farms surveyed in 2000.

APEC is most commonly treated with antibiotics, but this survey found high resistance, with most APEC strains resistant to two or more of five antibiotics. Resistance to tetracylines was found in 66% of 98 randomly selected strains of APEC in 2000, and resistance to ampicillin/amoxycillin was found in 59%. Half the strains were resistant to trimethoprim plus sulphonamide, and 36% to flumequine. Resistance to enrofloxacin was least common, and was found in only 13% of the strains. Only 5.1%s showed resistance to the five antibiotics, but 27.55% were resistant to four antibiotics, while 17.35% were sensitive to all five, a low figure.

Alternative measures, such as vaccination, should be used, given this high resistance to antibiotics, and the public health concerns involved.

Soft shells

Causes of hens laying eggs with soft egg shells

Source: Victoria Roberts
Country Smallholding October 2002 p23

Hens may lay eggs with soft shells because they have oviduct infections affecting the shell gland. Terramycin powder may help, and it can be administered in the hen's water. Young hens may also be affected by Infectious Bronchitis, which may mean that their eggs never have shells. Hens may start to eat their own eggs, and once they do this, it is not easy to get them to stop. Triggering broodiness may help, for example by excluding light from the nest box and placing eggs in it.

Pancreatic atrophy in a peregrine falcon (Falco peregrinus)

Case of young peregrine falcon with pancreatic atrophy

source: J.H. Samour and J.L. Naldo
Veterinary Record vol 151 no 4, July 27 2002
starts p124, 2 pages long

The pancreas is involved in the production of insulin, levels of which are lower in birds than in mammals. Pancreatic atrophy has been reported in a budgie and a macaw. This case involves a female peregrine falcon some eight-months-old, studied in the Falcon Medical Research Hospital in Saudi Arabia. The bird was initially in good condition, though trematode ova were found in her faeces, and the falcon was treated for this.

Nine days afterwards the falcon was checked again, and was found to have dropped in weight to 828 grams from 928 grams, though she was reported as eating normally. Mild air sacculitis and lung congstion were noted, and she was admitted to the hospital with a tentative diagnosis of air sacculitis and mild pneumonia. Her faeces were large and solid, and no endoparasites were found, while her white blood cell count was moderate high, and heterophilia was noted. Her weight dropped to 680 grams after a week, though she was eating well. High serum amylase was noted, suggesting pancreatic disorder. She still lost weight, though she was eating large amounts, and she developed coprophagia on the tenth day following her admission, eating her faces immediately after passing them. She died on the 14th day after entering the hospital.

A post-mortem found her pancreas to be dark grey-purple, small and mottled, and other findings were consistent with reactive pancreatitis and pancreatic atrophy. Clear diagnosis was not possible when the falcon was admitted. It is rare that clincial diagnosis can be achieved with living birds with pancreatic disorders, though serum amylase levels may be a helpful indicator. There is a need for more information on serum amylase ranges in normal birds. The peregrine in question had levels of 2508U/litre, which is very high, ie higher than the upper limit previously noted at the hospital. The peregrine was probably already too ill for therapy to have had any effect, though a tentative diagnosis was made that she was suffering from a pancreatic disorder.

Chicken droppings

Worm parasites can affect hens

source: Victoria Roberts
Country Smallholding August 2002 p19

Hens can suffer from parasites in the caecum, which is a section of the gut where fermentation of plant food takes place, as part of digestion. The caeca are emptied with every tenth or so dropping, and this type of dropping tends to be paler and may be foamy. The colour and consistency of droppings are also affected by the hens' food. Sometimes hens can suffer from worms in their caeca, which turn droppings foamy, and the flock will then need a worm treatment, such as Flubenvet.

Incubating Pekin bantam eggs

Low temperatures in an incubator can lead to chicks with deformed legs

source: Victoria Roberts
Country Smallholding August 2002 p19

Newly hatched chicks may suffer from deformed legs if eggs are incubated at temperatures that are too low. This may happen when hens leave eggs for too long, and if incubator temperatures are not correct. The incubator temperature should be 37.7 deg C or 100 deg F, taken using a thermometer on the top of the egg. Temperatures at the egg may be too cool if 37.7 deg C is only achieved in the top parts of incubators rather than lower down where eggs are located. Incubators should also be thoroughly cleaned with Virkon after use, since bacteria breed fast in incubators. Too high humidity levels should be avoided, since this can slow hatching.

Newcastle disease outbreaks in Italy during 2000

Inquiry into Newcastle disease epidemic in Italy

Source: I. Capua et al
Veterinary Record May 4 2002
starts p565, 4 pages long

There was an epidemic of Newcastle disease in central and northern Italy, following a serious epidemic of avian ‘flu, in 1999 and 2000. Newcastle disease is caused by a virus, avian paramyxovirus serotype 1, and is extremely contagious, as well as serious, with a death rate of over 50% for chickens.

The preceding avian ‘flu epidemic lead to the loss of more than 13 million poultry from infection and culling. This meant that eggs were imported from outside Italy, and chickens were kept in greater stocking densities where the ‘flu epidemic had not hit, since supply had dropped elsewhere. Vaccination programmes to protect against Newcastle disease were reduced or abandoned because the population was not homogenous, and there were also fears of the impact of reactions to vaccines where the birds were overcrowded.

These conditions favoured the emergence of Newcastle disease, and 254 outbreaks were dealt with from May 5 2000 to December 31 2000. Backyard flocks accounted for 219 of the outbreaks, 17 occurred at dealers, with a further 17 at intensively reared establishments, and one ostrich farm was hit.

The symptoms included listlessness, depression, tremors and wing paralysis, with birds dying between 24 and 48 hours after showing symptoms.

The infection was traced to a broiler hatchery, which had imported eggs from elsewhere in Europe, and the disease then spread to dealers, and from dealers to farms. The most susceptible birds were guinea fowl and chickens, with ostriches, pheasants and turkeys also affected, but less susceptible. The disease may have entered the hatchery through faeces on egg shells. It is not clear where it came from, but it may have been undetected in countries using a vaccination programme, since it is more likely to be detected where the population is immunologically naïve, where the clinical disease is more likely to appear.

There is a need for more monitoring to detect the disease in Europe. There were also problems during the Italian epidemic due to the large numbers of backyard flocks involved. Imposing a protection and surveillance zones for many small flocks involved a great deal of effort. There is a case for less stringent controls, since outbreaks tend to be self-limiting when they occur in naïve backyard flocks. There are problems in defining ‘backyard flocks’ and this could be done by looking at where the birds are slaughtered and consumed, and whether consumption is local, or whether the birds go into the industrial circuit.

Eggs and chilli

Dealing with egg-eating in hens

source: Victoria Roberts
Country Smallholding May 2002 p23

Hens may start eating eggs after laying a soft shelled egg. Eating a soft-shelled egg can teach them that eggs are good to eat. It’s better to prevent egg-eating, as it’s not easy to stop it once the hen has begun. Hens should have grit so that the egg shells are strong, and the nest box should be kept dark, with the entrance curtained using a vertically cut bin bag or other methods. Objects that look like eggs, such as golf balls, can also be used to confuse birds, and give signals for young birds to find laying places. Adding chilli to a hen’s food does not work, since hens do not find chilli to be hot.

Mis-shaped toes

Bent toes in chickens

source: Victoria Roberts
Country Smallholding April 2002 p20

Bent toes in chickens are often inherited, though they may have other causes. Inappropriate temperatures in incubators can also lead to curling toes, as can vitamin deficiencies. Chicks born with club-shaped feet have to be culled, due to their inability to walk. However, toes that are only slightly bent do not seem to have adverse effects on chickens’ production, though they may be more vulnerable to arthritis.

Off-colour hen

Significance of purple combs in chickens

source: Victoria Roberts
Country Smallholding April 2002 p21

Chickens with purple combs have circulatory problems, especially heart disease. There is usually no treatment, though sometimes a broad-spectrum antibiotic can help, if the condition is due to a bacterial infection. This condition tends to affect older birds and chickens from large breeds, which may go purple when they are washed in preparation for a show. Chickens with purple combs tend to become sluggish, due to oxygen deprivation, and they may have green droppings, since the bile content rises.

Paralysed Hamburg

Symptoms of Marek’s disease, and its prevention

source: Victoria Roberts
Country Smallholding April 2202
starts p20, 2 pages long

Some ‘well bred’ large breeds of chickens are vulnerable to Marek’s disease, which is a viral disease that stops legs from functioning, though they still have feeling. One or both legs may be affected. There is no cure, so the chickens have to be culled. Stress can trigger attacks, and attacks often come when chickens are about to come into lay.

Infected chickens are infectious for life, and the virus can persist in the dust of poultry houses for 12 months. Vaccination is one way of tackling the problem, though it has to be continued with each new chicken bought, and new generations of chickens, once a vaccination programme has started. Culling is another solution.

Red kite comeback may help restock Europe

Red kite numbers increase in Britain, but kites face threat from rat poisons

source: Brian Unwin
Independent January 1 2002 p3

Numbers of red kites are increasing in the UK, while they are falling in other European countries, including Spain. Many kites used to restock Britain had come from Spain, and Britain may end up providing kites for locations in mainland Europe.

Red kites are under threat from brodisacoum and bromadioline, used as rat poisons. They were also attacked by gamekeepers from the late 18th century, only surviving in central Wales, until they were reintroduced in Scotland and England from 1989. There are 431 pairs of kites in the UK in 2002, compared with 69 pairs in 1989.

Gigrin Farm in Powys, Wales, attracts large numbers of tourists to watch its kite gathering. The farmer feeds kites with meat, and over 150 kites go to feed there.

Spicy chicken

Capsaicin reduces Salmonella enteritidis infections in chickens

source: New Scientist August 25 2001 p5

Research at Virginia Tech University, Blacksburg, has found that chickens given food containing capsaicin, found in chilli peppers, were less likely to carry Salmonella enteritidis internally in their organs. The birds were exposed to the bacteria, and the number of infected birds was halved if they had been given capsaicin. Chickens do not appear to be able to taste chilli peppers as hot, and the meat from chilli-fed chickens does not appear to taste of chilli either.

Observations on the significance of diagnostic findings in egg-binding of Psittaciformes

Egg binding in the parrot family

source: M-E. Krautwald-Junghanns, V.M. Kostka and H. Hofbauer
Veterinary Record (1998) 143
starts p498, 5 pages long

A survey of 2,192 Psittaciformes has found 60 birds, (2.74% of the sample) cases of egg binding. The parrot family is not easy to sex, so the sample included males, estimated at around half the total. Egg binding is especially common in cockatiels, at 15.75% or 20 birds of 127, and budgerigars, at 5.37%, or 19 birds of 354, in this sample. It is rare in some parrot species, eg the Amazona species at 0.18% (one bird of 555), and Psittacus species (including African Grey parrots), at 0.22% (one bird of 464). Rates for the Ara species (including blue and yellow macaws) were 4.7% (seven birds of 149), and for Cacatua species (including sulphur crested cockatoos) were 2% (3 birds of 149).

Egg binding can be linked to malnutrition. Vitamin D, vitamin E, selenium and calcium supplies are important for successful breeding. Stress may be a contributory factor, eg long daylight hours, low humidity, an unsuitable temperature range, and social stress, from a new bird partner, or from humans, may also contribute. Egg binding may also be directly caused by weak or absent tonus of cloacal musculature or the oviduct, large eggs, eggs with soft or no shells, or rough surfaces, and adhesions affecting the oviduct and eggshell.

Affected birds are more likely to be caged than in an aviary, but being paired or single appears to make no difference. Birds are more likely to suffer from egg binding if they have never bred before. Four of the sample had previously bred, though 32 of the others had previously laid eggs, and 24 were laying for the first time. Seasonal factors do not appear to be important. Reproductive tract disease was evident in 36 cases.

Symptoms included a swollen abdomen in all cases, with 36 of the birds having problems with defecation. Other symptoms can include being unable to fly, and standing in a wide-legged way.

A diagnosis was possible in 70% of cases just by looking at the bird, taking the bird’s history, and palpating its abdomen. Radiography helped in diagnosing birds with eggs deep inside the bird, but eggs with thin or no shells could not be reliably diagnosed either by palpation or radiography. Radiography was also little help in diagnosing eggs with laminated shells. Ultrasonic examination helped in diagnosing eggs with defective and thin shells, but roughness of egg shells was not easily observable using ultrasound.

I spy with my duck's eye

Ducks sleep with half their brains awake

source: Alison Motluck
New Scientist February 6 1999 p8

Ducks can sleep with half their brains awake, according to research on mallard ducks, carried out by Indiana State University researchers. Niels Rattenborg and his team argue that birds maintain alertness in half their brains as a precautionary measure. They found that birds were more likely to sleep with one eye open if they were located on the edge of sleeping groups. These birds could detect video images of predators in less than a second. The birds were videotaped, and also given electroencephalograph tests, which showed that one brain hemisphere was in slow-wave sleep, and the other hemisphere, opposite the eye that was open, was alert. This research was reported in 'Nature', vol 397, p397.