Some Information on Diseases in Raptors

Some Information on Common Diseases

I am not a vet so this information is not meant as advice on how to diagnose or treat your birds and should not be taken as such- it is presented as an overview for background information only!

  An infectious disease can be defined as a disease caused by another living organism. They can be classified as

·       Parasitic

·       Bacterial

·       Fungal

·       Viral

As most captive raptors are kept individually or in pairs the spread of infectious diseases is usually limited.  The commonest vehicles for infection are

·        Food items - special care must be taken when feeding dead birds to raptors to minimise the risk of  transferring avian pathogens.

·        Contaminated aviaries and equipment (gloves, boxes, etc) carrying infections from other birds.

·        Infected wounds.

Parasites

  In large numbers parasites will cause both damage to the feathers and irritation to the birds. Heavy infestations are sometimes a sign of the presence of other disease. Lice species are mainly host-specific and the life cycle is direct i.e. it occurs entirely on the body of the host, the eggs will hatch in 3-4 days and the lifecycle takes around 30 days . Control of the parasite can be achieved with at least two applications of a suitable insecticide at intervals of 10 days.

Ticks

Acarina will occasionally be found on raptors, especially engorged adult females attached to the head. They can cause a severe, and possibly fatal, haemorrhagic reaction.

Mites

 Red Mites are a  problem when raptors are kept in sheds previously occupied by poultry.  Spraying or painting such housing with a persistent insecticide, before being used to house raptors, will control the parasite as its life cycle is indirect, it feeds on the birds but breeds off the birds.

Myiasis

 the infestation of infected wounds by the larvae of  certain species of flies, Diptera, can be life threatening and requires through cleansing of the wound and local treatment with insecticides and antibiotics together with systemic antibiotic and supportive treatment.

Other external parasites are flat flies, Hippoboscidae, fleas, Siphonaptera, mosquitoes and midges and black-flies,

 Nematodes

Can infest raptors, Capillaria and Ascaridia appear to be the commonest. Capillaria will cause problems mainly in the upper alimentary canal, especially in the form of white necrotic patches on the mouth of Falconidae. Syngamus trachea, the gape-worm, is often found in the trachea of buzzards and barn owls. The life cycle of nematodes is indirect, and in some cases involves an intermediate transport host, hence the control of nematodes requires attention to the hygiene of the birds’ environment as well as medical treatment .

Frounce,

Protozoan parasites can cause several significant disease problems in raptors.  Trichomoniasis usually appears as necrotic areas on the pharynx causing the bird difficulty in swallowing or to worry at its mouth. The commonest source of infection is other birds, especially pigeons, used as food. Freezing carcases before feeding will kill any Trichomonads [but not all pathogens].

Coccidial oocysts are often found in routine examination of raptor mutes.  Their presence in small numbers may not necessarily indicate a problem, however, in large numbers in a sick bird they do require treatment, together with a thorough investigation of the patient’s general health to eliminate any co-existing disease processes. Infestation with Caryospora spp. has been associated with a high mortality in aviary bred Merlins.  The life cycle of the parasite is indirect and attention to the hygiene of the birds’ environment is essential to control infection.

Bacterial Infections

Both localised and generalised infections caused by bacteria are frequently found in raptors.

Common  infections include :-

  Infected Wounds, commonly seen with bite wounds, especially to the legs, caused by prey or talon and bite wounds to the head and body caused by other raptors. A major problem is found with infected pressure sores on the weight bearing surface of the feet. Potentially infected wounds usually respond well to thorough cleansing of the site at the earliest opportunity together with the use of local antiseptics or systemic antibiotics.

 Conjunctivitis, often associated with infra-orbital sinusitis. Best treated with local ophthalmic antibiotic preparations [chlortetracycline, fusidic acid] and systemic fluoroquinalones [enrofloxacin – Baytril., see formulary].

Panopthalmitis, caused by a talon wound from another raptor.  Such infections are potentially fatal due to infection entering the cranial cavity via the optic nerve and causing a meningo-encephalitis. Such wounds require immediate antibiotic therapy and, possibly, partial enucleation of the eyeball.

Bumblefoot, is a bacterial infection of the dermal and sub-dermal tissue of the weight bearing areas of the foot. Lesions start as pressure sores , develop to ulcers which then, once infected ,usually with Staphylococcus, lead to lesions of the sub-dermal tissue, which may eventually spread to cause tenosynovitis, arthritis and osteomyelitis. Early lesions can be controlled with local dressing, systemic antibiotic treatment and improvement of the perches [natural branches, covering perches with Astroturf. Advanced cases will usually require surgery.

Septicaemic infections may be caused by a variety of bacteria including Mycobacteria tuberculosus, E.coli, Pasturella spp., Staphylococcus spp. Diagnosis of such conditions is difficult in a live bird, affected birds showing the typical ‘sick bird’

syndrome, diagnosis is usually only made with a post mortem examination to determine the pathogen and the likely source of infection and preventative measures  can then be taken,  to protect other birds.

The alimentary canal of raptors carries a normal flora , including E.coli, Streptococcus spp., Bacillus spp. and Proteus spp.. Problems in the crop and the intestine can be associated with newly introduced pathogens or overgrowths with existing bacteria. Crop infections can cause regurgitation of foul smelling ingesta or poorly formed pellets, whilst enteritis can lead to symptoms of diarrhoea, where the mutes are very green, mucoid and smelly. Such birds need supportive care to prevent dehydration and antibiotic treatment to overcome the infection, usually with E.coli. It would appear that Salmonella spp infections are not common in raptors.

Uro-genital infections are usually associated with E.coli , associated with ascending infections from the cloaca.  Acute orchitis can cause sudden death in males. In females, infections in the oviduct can cause infertility and may be associated with poor egg shell quality.  They may also be associated with a peritonitis caused by the release of yolk material to the peritoneum either directly from the ovary or by reflux from the oviduct. This condition is termed egg peritonitis and is frequently fatal.

Bacterial infections are commonly associated with embryonic death in both parent incubated and artificially incubated eggs. Infection can be acquired within the female’s oviduct before the egg is laid or afterwards by faecal contamination.

Newly hatched chicks are frequently affected by bacterial infections either septicaemia caused by a variety of organisms or localised infections such as yolk sac infection or conjunctivitis.

  Fungal infections

Infection of the respiratory tract with the fungus, Aspergillus spp. is a common and serious problem in all types of raptor.  Infection is air-borne, with the spores lodging at various site within the respiratory tract.The spores can then develop into either an actively growing mycelia or possibly a slow growing or arrested  infection which will appear to lie dormant until the bird is stressed or immunologically compromised.  Symptoms are a combination of physical damage caused by the fungal growth and secondary bacterial infection and the effects of mycotoxins the bird may show respiratory noises, change of voice and a severe weight loss.  Treatment is unlikely to be effective is once the disease has progressed to the point of producing clinical symptoms.  The fungus is a saprophyte and present on organic material, especially mouldy hay and straw. Hence improvement of the hygiene of the environment may reduce the level of infection.

Viral infections

Many virus infections have been demonstrated in raptors, however, mostly by serology and in the absence of clinical symptoms. Some of the more significant virus infections are:-

Paramyxovirus type 1 - the cause of Newcastle disease in poultry has been demonstrated in raptors and recorded as causing illness, central nervous signs and death.

Herpes virus. Several distinct herpes viruses (falcon, owl and pigeon herpes viruses) have been isolated from raptors and have been shown to associated with fatal infections. Recovered birds can remain as life-long carriers. No vaccines are available.

Pox virus.  Pox virus in raptors is seen mainly in warmer climates or in imported birds.  The infection is carried between birds by biting insects, primarily mosquitoes, and is usually self-limiting, although damage to the eyelids leads to a severe conjunctivitis that may require treatment.