Abstract
INTRODUCTION
A bird should be examined in its cage for the presence of dried or fresh discharge around the eyes and nostrils, the respiratory rate, laboured breathing and tail movements. This is followed by auscultation to determine an increase or decrease in respiratory and abnormal respiratory sounds. Laparoscopy is a useful tool in the examination of the abdominal air sacs (Fig. 1). Radiography (x-ray) is also helpful in determining lung lesions, air sacculitis, and space-occupying lesions. When a respiratory condition exists samples for further examination should be taken. Swabs for viral, bacterial and fungal cultures can be taken from conjunctival sacs, nares, choana, and trachea. Fluid can be aspirated from the infra-orbital sinuses and thorax. Biopsy material can be taken from the mouth, esophagus, trachea and abdominal air sacs. Blood samples are often taken for blood chemistry, bacterial or fungal culture and for serological tests.
GENERAL PRINCIPLES OF THERAPY
Supportive Treatment: Supportive treatment consists of adequate nutrition, and the provision of a suitable environment. Weakened birds may have to be force fed at regular intervals in order to supply their energy needs and the environment should be warm and free from outside disturbance.
Medical and Surgical Treatment:
Medical treatment can be administered locally in the form of eye drops, nasal drops, sinovial injections, ointments, aerosol spray, powder or systemically by oral and parenteral routes. Oral administration to single patients is best done by individual dosing. For group treatment, drugs can be given in soft food, as treated grain or in the drinking water. The success of water treatment is variable depending upon the species, debilitation of the bird and environmental conditions. Intramuscular injection into the caudal part of the pectoral muscles is the generally preferred parenteral treatment. Anti-fungal treatment can be administered locally, generally, orally, or by I.M. injection. Anti-parasitic treatment is usually given orally for anthelmintics (individually or in the food or water) and insecticides are given by aerosol or dust inhalation, powder, spray, injection or spot-on treatment. Surgical treatment consists mainly of repair of injuries and the removal of obstructions. Obstructions include fibrinous exudate in the air sacs and sinuses, blocked gastrointestinal tract, foreign bodies and neoplasms.
RESPIRATORY DISEASES CAUSED BY INFECTIOUS AGENTS
Contagious diseases frequently occur in pet shops and aviaries and are rarely encountered in individually kept pet birds. Infectious respiratory diseases can be divided into infections of the respiratory tract and general infections accompanied by respiratory symptoms. It is not always possible to distinguish the two.
Viral Infections: Pox - in psittacines, pox virus has been isolated from many species including Amazon parrots, cockatiels, grass parakeets ( esp. budgerigars), lovebirds and other species. Avian pox is spread by contact, aerosol droplets, and insect or mechanical transmission. Severe diphtheritic oral, oesophageal and crop lesions may be seen in pox infections. The skin lesions are small, yellow or wart-like proliferations around the eyes and beak as well as on the skin of the head and neck. The degree of respiratory involvement depends upon the severity of the lesions. Pneumonia and congestion of the upper respiratory tract often make cases difficult to treat. Vaccination of unaffected birds with pigeon pox or canary pox vaccine helps to control outbreaks in an aviary. Symptomatic treatment of clinical symptoms may help to reduce the severity of an outbreak.
Newcastle Disease: Newcastle disease virus (NDV) is a highly contagious viral disease which attacks all avian species. There are several forms of the virus. Some forms produce death shortly after infection with the virus (peracute form) while other forms are sub-clinical and birds remain carriers. Velogenic Viscerotropic Newcastle Disease (VVND) is an extremely virulent form of NDV and is commonly the type found in imported psittacine birds. Several outbreaks of VVND in poultry have been traced back to imported birds. Birds exposed to the disease should be isolated from all other birds and in some countries mandatory slaughter is imposed. Killing of all exposed birds is the only method of eradication of the disease.
Herpes Viruses: A number of different herpes viruses have been found in many species of psittacine birds with a varying degree of respiratory involvement. Pacheco's parrot disease is the most frequently encountered. Pacheco's parrot disease causes severe respiratory symptoms characterized by conjunctivitis, rhinitis, pharyngitis, laryngitis, tracheitis, broncho-pneumonia and air sacculitis. Symptomatic antibiotic treatment and good management have no effect on the disease process. Treatment, therefore, is not warranted. Isolation and strict sanitization may help to prevent the spread of the disease.
Other Virus Isolates: Other viruses have been isolated from psittacines including adeno, corona, papova, and orbi viruses. Respiratory symptoms vary with the virus and the severity of infection. Viruses are difficult to treat and seldom respond to symptomatic treatment.
Bacterial Infections: Psittacosis - Psittacosis (Parrot Disease, Chlamydiosis, Ornithosis) causes systemic illness and as the disease progresses respiratory signs develop. Lethargy, diarrhea, sneezing, copious nasal discharge and conjunctivitis are seen. Isolation of the organisms from blood, feces, or other tissues may take weeks to complete. For a quick diagnosis, a conjunctiva} impression smear can be stained with Stamp's Brucella stain, Giemsa's, Gimenez's, or Macchiavellos' stain (Fig. 2). Chlamydia, the organism causing psittacosis, becomes visable as very small intracytoplasmic inclusions under microscopic examination. A negative result does not necessarily mean a negative diagnosis. Several examinations may be necessary to determine the infection. The disease is transmissable to humans and care must be taken when handling birds suspected of having psittacosis. All newly introduced birds should be put on a treatment regime of tetracyclines for 45 days. Treatment of infected birds should be done with caution. Euthanasia is recommended for inexpensive birds diagnosed as having psittacosis.
Tuberculosis: Mycobacteriosis (tuberculosis) occurs in all species of birds. Few clinical symptoms are characteristic of T.B. infection in parrots. Some birds may harbor the infection for years without showing clinical symptoms until stress is placed upon them. Symptoms of T.B. infection include wasting of the breast muscles despite a good appetite, respiratory distress, lethargy, and feather disorders. The recommended control of the disease in T.B.-positive birds is disposal of the infected bird. Dirt floors and cage litter should be disinfected with a phenolic germicidal detergent where infection has occurred.
Mycoplasma: Mycoplasma spp. are known pathogens of the respiratory system of psittacine birds frequently causing air-sacculitis. Clinical symptoms of the disease are often not noticed because the signs may be obscure. Respiratory rales, dyspnoea, nasal discharge and sinusitis have been recorded from Mycoptasma spp. infections. Diagnosis of the condition is made by the growth of organisms on culture plates and by serological and biochemical tests. Some antibiotics favor the growth of Mycoplasma spp. therefore advice should be sought from a veterinarian regarding proper treatment.