The notes on the following pages contain advice on commonly encountered diseases. They are not exhaustive and specific advice should be obtained if a health problem with pigeons occurs.
Candidiasis. (Crop Mycosis)
Causes and Clinical signs: Candidiasis is caused by a yeast-like fungus and affects the mouth, oesophagus and crop. It may be present in small numbers in the upper gastric tract of healthy, normal birds and only rarely causes clinical disease. Where disease does occur it is usually associated with prolonged over-use of antibiotics together with unhygienic environmental conditions. Affected birds will be in poor bodily condition and will fail to perform.
Diagnosis: Diagnosis is based on microscopic detection of the yeast together with gross clinical lesions in either live birds or on post mortem examination.
Prevention: Birds kept in hygienic lofts and given only antibiotics as prescribed by a veterinary surgeon are (in the absence of other debilitating diseases) unlikely to get clinical disease due to Candidiasis.
Canker – Trichomoniasis
Microscopic view of Trichomonas
Causes and Clinical Signs: Canker is caused by a parasitic organism called Trichomonas colombi and three forms are recognised that affect the pharynx (throat), navel and internal organs respectively. The majority of adult pigeons are symptomless carriers of the organism but clinical cases may occur if the bird is under stress and in young pigeons the disease may be severe and even fatal.The disease is spread from adults to squabs in the crop milk and between pigeons by the oral route.
Pharyngeal Form: Cheesy yellow deposits are seen on the membranes of the pharynx at the back of the mouth. These deposits affect food intake and also breathing. Severely affected birds are depressed, food intake is reduced and they become emaciated. Affected birds may have diarrhoea and water intake may increase.
Navel Form: This form occurs in young birds that are affected in the nest box from infected crop milk dripping onto the nest box floor. A typical cheesy yellow deposit is present under the skin at the navel and it may spread from here to the internal organs.
Internal Form: The internally affected organs include liver, crop and lung in which cheesy yellow deposits may be found. The clinical signs of the internal form vary depending upon the organ involved but usually diarrhoea and emaciation are features of this condition.
Diagnosis: Diagnosis has to be based on the clinical signs in the living birds. Samples of crop smears are positive in many adult birds and diagnosis is dependent on the number of organisms present. Post mortem examination of dead birds will give a positive diagnosis of the internal form. The disease needs to be distinguished from Pox, Tuberculosis, Aspergillosis and Salmonellosis.
Treatment: Treatments for Trichomonas infections are limited to drugs that may be prescribed by a veterinary surgeon under the cascade principle. Usually all susceptible and in-contact birds would be treated. In some birds a broad-spectrum antibiotic or multi vitamin may also be recommended.
Prevention: No flock can be permanently kept free of Trichomonas. Due to its severity in young birds we recommend routine treatment of all birds at the end of the flying season and treatment of all adults after egg laying and before the squabs are hatched.
Chlamydia – see under Ornithosis
Microscopic view of Coccidial Oocysts
Causes and Clinical Signs: Coccidiosis is due to a parasitic protozoon organism that affects the bird’s intestines. Two types of coccidia affect pigeons: Eimeria columbanum and Eimeria labbeanna. The clinical disease due to these organisms is identical. Coccidia in the intestines produce ‘oocysts’, which are passed out in the faeces. These mature in the environment and will then affect other birds if ingested. Most adult birds carry low levels of these parasites. Only when large numbers of parasites are present is treatment necessary. We interpret coccidial oocyst counts as follows:
Oocysts per gram of faeces
Less than 3,000
3,000 - 20,000
Moderate infection - performance will be affected
20,000 - 50,000
Severe infection - birds may show clinical disease
More than 50,000
Very severe infection
Usually raised levels of coccidial oocysts are associated with sub-optimal performance but in young birds and adults under stress an acute clinical form of the disease may be seen. The parasite affects the lining of the intestine causing diarrhoea and blood may be present. Affected birds are depressed, rapidly become emaciated and may die.
Diagnosis: Microscopic examination of faeces is necessary to diagnose the disease in live birds. As many birds have a low level of disease it is the number of oocysts present which is important when arriving at a diagnosis. The disease needs to be distinguished from Salmonellosis, Trichomoniasis, bacterial gut infections and worm infestation.
Treatment: Treatment for coccidiosis will be dispensed by the veterinary surgeon as necessary. Follow up medication with multivitamins may also be beneficial.
Prevention: Good hygiene in the loft is essential, as is the provision of clean uncontaminated food and water. If birds show signs of diarrhoea, a coccidial oocyst count is advised. Routine faeces analysis before pairing is also recommended. Most disinfectants fail to destroy coccidial oocysts and they can survive for long periods of time in the environment. We advise that lofts are disinfected with Bioocyst ® a product that kills coccidial oocysts (in addition to viruses, bacteria and fungi).
Causes and Clinical signs: Enteritis is inflammation of the intestinal lining, usually caused by infective agents such as parasites, viruses and bacteria but it may also be caused by poisons. The most serious consequence is often marked dehydration of affected birds. The most common parasites that cause enteritis are worms and coccidiosis. (see later for further information on these conditions).
A wide variety of viruses can cause enteritis including Paramyxovirus, Circovirus, Adenovirus and Herpesvirus. Bacteria implicated in enteritis include Salmonella, Clostridia, certain strains of E.coli, also Spirochaete bacteria and other motile bacteria that can be identified on vent swabs.
Microscopic view of Clostridia bacteria
Diagnosis: Laboratory testing together with the clinical signs are necessary to identify the cause of any outbreak of enteritis.
Treatment: Where viruses are suspected there are no anti-viral drugs available to treat the pigeons so treatment of suspect viral enteritis is symptomatic using products to re-hydrate the birds and products to support their immune system. Where bacteria are the cause of enteritis then suitable antibiotics are used depending on the type of bacteria present together with supportive therapies.
Many cases of enteritis may be due to a combination of causal agents and treatment will reflect this.
Causes and Clinical signs: Ticks, mites and lice can all live on the body of pigeons and will cause damage of varying degrees depending on the type and severity of infestation. Anaemia, feather damage, respiratory problems (air sac mites) and poor growth in young birds may all result from external parasite infestation. Some external parasites spend their whole life cycle on the bird and spread is by direct bird to bird contact e.g. mange mites, plumage lice, feather mites, quill mites and scaly leg mites. Other parasites spend most of their time in the environment only visiting the pigeon to feed e.g. red mites and ticks.
Microscopic view of red mite
Diagnosis: Ticks are common during the warm summer months and are visible to the naked eye. Mites are very small and can rarely be seen by the naked eye. If infestation is suspected samples need to be submitted to the laboratory for microscopic examination. Lice are just visible to the naked eye – if in doubt, their presence can be confirmed by microscopic examination. The red mite spends the day in cracks and crevices of the pigeon loft only visiting the pigeon at night to feed. Where cases of anaemia or reduced performance and agitation are obvious in birds, external parasites should be suspected and regular visual inspection of the birds should be undertaken to identify the presence of ticks and lice.
Treatment: Treatment of birds with a parasiticide together with a thorough cleaning and disinfection of premises is necessary where external parasites cause problems. External parasites are a particular problem to young birds. Thorough cleaning of the loft before the breeding season is essential together with treatment of the birds if examination shows them to be infected.
Prevention: Regular cleaning and disinfection of the loft with a suitable product will help control the population of external parasites. The practice can give advice and supply suitable products to control external parasites on pigeons.
Cause and Clinical Signs: Birds infected with Haemophilus bacteria suffer from a severe conjunctivitis, which affects both eyes. In this condition the eyelids are markedly swollen and there is purulent discharge. Affected birds often show respiratory signs due to infection of the upper respiratory tract. The disease spreads rapidly by direct contact and droplet infection from one bird to another. Suspect birds should never be sent for racing and suspect birds and in-contacts should be isolated until the situation has been resolved.
Diagnosis: Diagnosis is on clinical signs and laboratory culture from the eyes or nasal discharge.
Treatment: As this is a bacterial infection, a suitable antibiotic such as a Tetracycline based drug can be prescribed by a veterinary surgeon once the disease has been confirmed.
Prevention: Isolation of suspect infected birds together with a correct diagnosis and suitable treatment is necessary to prevent the rapid spread of this condition in a loft once an infected bird is present.
Mycoplasmosis – see under Respiratory Disease
Causes and Clinical Signs: Ornithosis is caused by a micro-organism called Chlamydia psittaci. It is an unusual organism as it is susceptible to antibiotics like bacteria but lives within and destroys body cells like a virus. Clinical signs vary from poor performance to an acute disease causing a marked conjunctivitis, decreased appetite, respiratory disease, diarrhoea and death. The acute form is particularly prevalent in young birds and older birds under stress. In some cases the conjunctivitis can lead to secondary bacteria infection of the eye resulting in blindness. Recovered birds may carry the disease and subsequently spread it to other pigeons.
Diagnosis: Diagnosis of this disease in the live bird is difficult and must rely heavily on the clinical symptoms present. Blood tests will identify birds that have been exposed to the organism but are not a good indication of the present disease status. Where dead birds are available, samples from the liver or spleen can give a positive diagnosis in the laboratory. The disease needs to be distinguished from Mycoplasma and Haemophilus infection.
There is a very real danger of this infection being transmitted to man. Pigeon fanciers who suffer from a prolonged flu-like disease are recommended to consult their doctor who should be aware of their contact with pigeons. Where cases are diagnosed in pigeons DEFRA must be informed.
Treatment: Because of the danger of human infection, the risk to young birds and the fact that chronically infected birds are more prone to other diseases, the treatment of affected birds with Chlortetracycline for an adequate period is essential. Treatment lengths of 30 to 60 days would be recommended. The use of multivitamins may also be advised.
Prevention: No specific measures are available to prevent the condition. Try to maintain birds in good bodily condition and make sure the loft is regularly cleaned and disinfected. If the disease is suspected, veterinary advice should be sought.
Causes and Clinical Signs: Paramyxovirus infection is caused by a virus known as PMV3. Affected birds first show signs of an increased thirst and will pass very fluid, green faeces - this may be followed by nervous signs. The nervous signs seen include paralysis, torsion (abnormal twisting) of the neck and uncoordinated body movements – not all these signs will necessarily occur in each affected bird. In vaccinated birds the clinical signs are usually less pronounced.
Where cases are suspected in pigeons DEFRA must be informed.
Diagnosis: Diagnosis is based largely on the clinical signs and post-mortem analysis. The disease needs to be differentiated from Salmonellosis, other causes of wet droppings and other causes of nervous signs including poisoning.
Treatment: As this condition is caused by a virus no specific treatment is available. Antibiotics, multivitamins and electrolytes may be of benefit in supporting the birds.
Prevention: As treatment of Paramyxovirus is difficult due to the absence of useful antiviral agents, prevention of this disease is very important. Vaccines to prevent the disease are licensed for use in pigeons in the U.K.
Timing of Vaccination: The best time to vaccinate young birds is during mid-March. The young birds should be at least 3 weeks old when vaccinated and vaccination should be completed 10 to 14 days before the onset of the old-bird racing season in April. This will prevent infection of susceptible young birds by virus brought back to the loft by the older birds. If vaccination cannot be completed before the old bird racing season then young birds must be kept separate from the older birds and vaccination must be completed 10 to 14 days before the start of the young-bird racing season in July. The best time to vaccinate older birds is during November and December before the start of the laying season. Vaccines are given subcutaneously (under the skin) in the midline of the neck with the needle towards the tail of the bird. Great care must be taken to keep the needles, bottles etc. as clean as possible. Needles should be changed after every ten birds or more often if they become contaminated. Take care in disposing of used needles; if purchased from the practice, they may be returned in a solid container so that they can be disposed of correctly. Any post vaccine reaction in the bird should be reported immediately to the veterinary surgeon.
Causes and Clinical Signs: Although not commonly seen in pigeons, it is one of the possibilities that must be considered when birds are ill. Poisoning in pigeons can be due to a wide variety of products so the clinical signs can vary greatly. Possible signs include nervous signs, diarrhoea, depression and sudden death. Poisoning may be from substances encountered away from the loft e.g. Organo-Phosphorous compounds or substances found around the loft e.g. Phenolic compounds, vermin baits and veterinary medicines used incorrectly. Where poisoning is suspected, any dead birds together with a full clinical history should be submitted to the practice.
Causes and Clinical Signs: Pigeon pox is caused by a virus infecting the bare skin around the eyes, on the beak, on the feet and internally within the mouth and throat area. On occasions infection of a wound on a feathered area of the body can occur. The lesions are typically scabby in appearance with pus often being present due to secondary bacterial infection.The internal form can be so severe that feeding and breathing are affected to the point that death occurs. Lesions typically occur 4 to 14 days after initial infection and may be present for several weeks.
Diagnosis: This is based on the clinical signs – the internal form affecting the mouth and throat may need a laboratory diagnosis to confirm this condition. The disease needs to be differentiated from canker with which the mouth form could easily be confused, and from Candida infection caused by a fungal infection of the mouth.
Treatment: As with paramyxovirus infection, this condition is due to a virus and no specific treatment is available. Antibiotics may be useful to combat secondary infections and multivitamins may be of benefit in some birds during the recovery phase.
Prevention: As no specific treatment is available, the prevention of the disease is very important. There is only one vaccine licensed for use in the U.K., this is the Merck Animal Health product Pigeon Pox Vaccine (Living) Nobilis.
It should be used only in lofts where the disease has been positively identified.
Only birds over six weeks old should be vaccinated and all the birds in the loft should be vaccinated at the same time. Annual re-vaccination should be done between the 30th September and the 31st December each year. If birds are vaccinated at any other time of the year it is important that they are withheld from racing for a period of six weeks after vaccination. Vaccination of young birds in spring may be advised in lofts where pigeon pox is endemic. The vaccine is administered by removing six to eight feathers from the thigh, the skin is stretched to open the feather follicles and the vaccine applied with the brush provided to the de-feathered area. Do not apply the vaccine to bleeding follicles and do not use a disinfectant to clean the skin before vaccination. With show birds it is recommended that feathers are removed from an area of the skin which is not obviously visible.
If Pox and Paramyxovirus vaccine are to be used together in a loft then both vaccines should be given on the same day. If this is not possible then a minimum gap of two weeks and preferably six weeks should be allowed between vaccinations. To check that pox vaccination has taken, examine the birds five days after vaccination: scabby deposits on the treated feather follicles should be obvious. The pox virus is very resistant and will remain infective for many months. It can be transmitted by biting flies and other insects. As a result good loft hygiene is important in the control of the disease.
Respiratory Disease – Mycoplasma
Respiratory disease in pigeons can result from a variety of infections - viral, bacterial and fungal but the most common organism underlying outbreaks of infection is Mycoplasma. Mycoplasma is endemic in the pigeon population and the majority of pigeons will carry the organism. The Mycoplasma organism is bacteria-like in many of its properties and for diagnostic purposes it can be cultured on a special media in the laboratory. However cultures may take several weeks so are not practically useful in an acute outbreak of disease. Stress conditions favour the development of the clinical disease in birds. The principle clinical finding is one of catarrh. Initially there is a clear nasal discharge which in time becomes thicker due to the presence of pus. Affected birds may breathe through open beaks and clear rattles and wheezes may be detected when the bird is examined. In a loft early signs of respiratory disease may be detected when listening to birds that are at rest. The disease appears to lower the bird’s resistance to other diseases and chronic infection can markedly affect performance due to respiratory problems. Internally the air sacs can be seen to be affected and secondary bacterial infections can occur at this site.
Diagnosis: The clinical presence of catarrh together with respiratory sounds are highly suggestive of this condition. Reduced performance in an otherwise healthy bird may also suggest that Mycoplasma is present. Post mortem examination shows typical signs in the respiratory system and the organism can be cultured in the laboratory if required.
Treatment: Antibiotic medication with Enrofloxacin, Tetracyclines, Tilmycosin, Tylosin or Tylamulin is effective against uncomplicated cases of Mycoplasmosis. These antibiotics may be prescribed by a veterinary surgeon where their use is indicated by the presence of disease.
Prevention: The disease spreads rapidly from pigeon to pigeon in close contact. Prevention is difficult as birds mix with birds from other lofts during the racing and show season. Eradication for any length of time is hence virtually impossible. The organism is easily killed by most disinfectants used to clean lofts. In lofts where the disease is known or suspected to be clinically present strategic use of suitable antibiotics at times of stress may be recommended by a veterinary surgeon, e.g. before the start of the breeding season, when young birds are being raised and at the end of the racing season.
Causes and Clinical Signs: Salmonellosis is caused by a bacterial infection and a significant number of different strains of Salmonella are capable of causing disease in pigeons. The disease is particularly severe in young birds and can be introduced into a loft by an apparently healthy carrier bird that can excrete the organism in faeces or saliva but which itself shows no clinical signs of disease. Young birds can be affected from crop milk or infected faeces. Salmonellae most commonly affect the intestinal tract and with infection localised in the intestines most birds are symptomless carriers. Clinically affected birds have enteritis which may be blood stained, they are depressed, rapidly become dehydrated and emaciated and death quickly follows if they are not treated. It is possible for Salmonellae to enter the blood stream and then a generalised infection will result. On post mortem examination the organism can be recovered from various body organs. In addition to the two forms of Salmonella recorded above, cases are seen where the organism localises in one or more joints. Affected joints are swollen and painful and movement of the joint is lost due to the pain involved. If the organism localises in the brain, nervous signs will be seen depending upon the area of the brain involved.
Diagnosis: Laboratory testing is required to confirm a diagnosis of Salmonellosis. Positive cases must be reported to DEFRA under the Zoonosis Order. The disease needs to be differentiated from other causes of diarrhoea (viruses, other bacteria, parasites etc.), injury to the joint and other causes of nervous signs including Paramyxovirus and poisoning. Where dead birds are available for post mortem examination cultures from the birds should determine whether or not the organism is present. In live birds faecal and mouth swabs may detect the organism but as birds can intermittently excrete the bacterium a single negative result does not definitely preclude the presence of Salmonella.
Most strains of Salmonella can cause disease in man. This can be very serious in the young, old and debilitated. Strict personal hygiene after handling birds and loft equipment and before eating / smoking is therefore essential.
Prevention: Isolate newly introduced birds and if there is any doubt have faeces and mouth swabs cultured for Salmonella. Good loft hygiene will reduce spread within the loft and where a loft is known to be affected then an eradication and control programme, which will depend upon conditions in the loft, needs to be agreed with the attending veterinary surgeon.
Viral Diseases of pigeons
Pigeons can be infected with a wide range of viruses for which at present no vaccination is available to prevent the diseases and no specific medication available to treat them. Both Paramyxovirus and Pox virus, for which vaccines are available, are described under their respective headings in this booklet. Other viruses that commonly affect juvenile pigeons include Circovirus which damages the birds immune system and makes it more liable to disease with other organisms, Adenovirus which can result in birds holding corn in their crop and regurgitating food and Herpesvirus which is responsible for Inclusion Body Hepatitis (a liver disease) and encephalitis (a disease of the brain). Together with Salmonella and E.coli, these three viruses are often implicated in outbreaks of ‘Young Bird Sickness’. In adult birds, Adenovirus infection results in increased mortality. Skin lesions containing Poxvirus and Wart Virus are often responsible for the ‘Blood blisters’ that may be found on the bodies of adult birds.
Young Bird Sickness
Causes and Clinical Signs: As its name implies this condition affects young birds and if severe can be fatal. Although affected birds show generally similar signs of holding corn in their crop, depression and scour, the disease can be due to a variety of viruses and bacteria and not all are necessarily present in an outbreak of disease. Viruses that have been isolated from affected birds include Circovirus, Adenovirus and Herpesvirus and bacteria that have been isolated include Salmonella and certain strains of E.coli.
Treatment: Treatment of Young Bird Sickness is based on controlling the bacteria with antibiotics and supporting the birds with re-hydration products, tonics and vitamins as they fight the viral infections.
Causes and Clinical Signs: Worms are intestinal parasites that can affect birds of all ages but due to some degree of resistance in older birds the more extreme clinical signs are more commonly seen in the younger birds. In mild infestations clinical signs may not be obvious. Weight gain in young birds may be adversely affected and in more severe infestations diarrhoea, depression and loss of condition, even emaciation, may be obvious, as may anaemia. Two types of worms affect pigeons, Roundworms and Tapeworms. Both large and small Roundworms will inhabit the birds intestine and these worms pass their eggs into the gut and are voided by the pigeon in its faeces. In the environment these eggs develop and are then ingested by the other pigeons. Of particular concern is the Capillaria roundworm which, although a small worm that can be easily missed when looking at a birds intestine, can cause considerable damage to the intestinal lining and so affect the condition and performance of the bird. Tapeworms require ‘intermediate hosts’ and these include snails, slugs and insects. Within these creatures the eggs develop and when swallowed by a pigeon another mature Tapeworm can develop.
Microscopic view of Capillaria Worm Egg
Diagnosis: In the live bird worm egg counts on faeces are a reliable indication of the level of infestation. Visual and microscopic examination of gut contents can identify worms post mortem.
Treatment: Either water or food medication is available to treat for roundworms; treatment for Tapeworms is not so easy. We recommend that all birds in a loft are wormed at the end of the racing season and again before pairing and at other times when egg counts show worming to be necessary.
Prevention: Regular removal of faeces from the loft (every day) is recommended as is the control of insects that may be intermediate hosts of the Tapeworm. A programme of regular worm egg counts should be started and birds treated when the counts show this to be necessary. Routine treatment of birds after the flying season and before pairing will help reduce the worm burden for the young birds.