Veterinary World, Vol.1(7): 217-219 REVIEW

Common Respiratory Diseases of Poultry

Shankar B.P.

Ph.D.Scholar, Department of Veterinary Pathology, Veterinary College, Karnataka Veterinary, Animal and Fisheries Science University Hebbal, Bangalore-24, India

There are many common and important Newcastle disease. VVND is not present in the diseases which can affect the respiratory system (air United States poultry industry at this time. passages, lungs, air sacs) of poultry. People keep Newcastle disease affects all birds of all ages. the birds for their use and generally include the Humans and other mammals are also susceptible chicken, turkey, duck, goose, quail, pheasant, to Newcastle. In such species, it causes a mild pigeon, guinea fowl, pea fowl, ostrich, emu and rhea. conjunctivitis. There are three forms of Newcastle Fowl Pox/chicken pox/sore head/avian disease, mildly pathogenic (lentogenic), moderately diphtheria: Most poultry-chickens, turkeys, pathogenic (mesogenic) and highly pathogenic pheasants, quail, ducks, psittacine, and ratites - of (velogenic). Newcastle disease is characterized by all ages are susceptible. There are two forms of fowl a sudden onset of clinical signs which include hoarse pox. The dry form is characterized by raised, wart- chirps (in chicks), watery discharge from nostrils, like lesions on unfeathered areas (head, legs, vent, labored breathing (gasping), facial swelling, etc.). The lesions heal in about 2 weeks. If the scab paralysis, trembling, and twisting of the neck (sign is removed before healing is complete, the surface of central nervous system involvement). Mortality beneath is raw and bleeding. Unthriftiness and ranges from 10 to 80 percent depending on the retarded growth are typical symptoms of fowl pox. In pathogenicity. In adult laying birds, symptoms can laying hens, infection results in a transient decline include decreased feed and water consumption and in egg production. In the wet form there are canker- a dramatic drop in egg production. like lesions in the mouth, pharynx, larynx, and The Newcastle virus can be transmitted short trachea. The wet form may cause respiratory distress distances by the airborne route or introduced on by obstructing the upper air passages. Chickens may contaminated shoes, caretakers, feed deliverers, be affected with either or both forms of fowl pox at visitors, tires, dirty equipment, feed sacks, crates, one time. and wild birds. Newcastle virus can be passed in Fowl pox is transmitted by direct contact the egg, but Newcastle-infected embryos die before between infected and susceptible birds or by hatching. In live birds, the virus is shed in body fluids, mosquitos. Virus-containing scabs also can be secretions, excreta, and breath. sloughed from affected birds and serve as a source Infectious Bronchitis/ (IB): Infectious bronchitis of infection. The virus can enter the blood stream is a disease of chickens only. A similar disease through the eye, skin wounds, or respiratory tract. occurs in bobwhite quail (quail bronchitis), but it is Mosquitos become infected from feeding on birds caused by a different virus. The severity of infectious with fowl pox in their blood stream. There is some bronchitis infection is influenced by the age and evidence that the mosquito remains infective for life. immune status of the flock, by environmental Mosquitos are the primary reservoir and spreaders conditions, and by the presence of other diseases. of fowl pox on poultry ranges. Several species of Feed and water consumption declines. Affected mosquito can transmit fowl pox. Often mosquitos chickens will be chirping, with a watery discharge winter-over in poultry houses so, outbreaks can occur from the eyes and nostrils, and labored breathing during winter and early spring. with some gasping in young chickens. Breathing Newcastle Disease/ pneumoencephalitis (ND): noises are more noticeable at night while the birds The highly contagious and lethal form of Newcastle rest. Egg production drops dramatically. Production disease is known as viscerotropic (attacks the will recover in 5 or 6 weeks, but at a lower rate. The internal organs) velogenic Newcastle disease, infectious bronchitis virus infects many tissues of the VVND, exotic Newcastle disease, or Asiatic body, including the reproductive tract. Eggshells Veterinary World . www.veterinaryworld.org . Vol.1, No.7, July 2008 217 Common Respiratory Diseases of Poultry become rough and the egg white becomes watery. Coryza is primarily transmitted by direct bird- Transmission: Infectious bronchitis is a very to-bird contact. This can be from infected birds contagious poultry disease. It is spread by air, feed brought into the flock as well as from birds which bags, infected dead birds, infected houses, and recover from the disease which remain carriers of rodents. The virus can be egg-transmitted, however, the organism and may shed intermittently throughout affected embryos usually will not hatch. their lives.. Birds risk exposure at poultry shows, bird There is no specific treatment for infectious swaps, and live-bird sales. Inapparent infected adult bronchitis. Antibiotics for 3-5 days may aid in birds added into a flock are a common source for combating secondary bacterial infections. Raise the outbreaks. Within a flock, inhalation of airborne room temperature 5°F for brooding-age chickens respiratory droplets, and contamination of feed and/ until symptoms subside. Baby chicks can be or water are common modes of spread. encouraged to eat by using a warm, moist mash. Infectious Laryngotracheitis (ILT): Chickens and Avian Influenza (AI) influenza: Avian influenza pheasants are affected by LT. Chickens 14 weeks can occur in most, if not all, species of birds. Avian and older are more susceptible than young chickens. influenza is categorized as mild or highly pathogenic. Most LT outbreaks occur in mature hens. In recent The mild form produces listlessness, loss of appetite, years, LT has also caused significant respiratory respiratory distress, diarrhea, transient drops in egg problems in broilers greater than 3 weeks of age, production, and low mortality. The highly pathogenic especially during the cooler seasons of the year. This form produces facial swelling, blue comb and wattles, is believed to be due to unwanted spread of LT and dehydration with respiratory distress. Dark red/ vaccines between poultry flocks. The clinical sign white spots develop in the legs and combs of usually first noticed is watery eyes. Affected birds chickens. There can be blood-tinged discharge from remain quiet because breathing is difficult. Coughing, the nostrils. Mortality can range from low to near sneezing, and shaking of the head to dislodge 100 percent. Sudden exertion adds to the total exudate plugs in the windpipe follow. Birds extend mortality. Egg production and hatchability decreases. their head and neck to facilitate breathing (commonly There can be an increase in production of soft- referred to as “pump handle respiration”). Inhalation shelled and shell-less eggs. produces a wheezing and gurgling sound. Blood- The avian influenza virus can remain viable tinged exudates and serum clots are expelled from for long periods of time at moderate temperatures the trachea of affected birds. Many birds die from and can live indefinitely in frozen material. As a result, asphyxiation due to a blockage of the trachea when the disease can be spread through improper the tracheal plug is freed. disposal of infected carcasses and manure. Avian ILT is spread by the respiratory route. LT is also influenza can be spread by contaminated shoes, spread from flock to flock by contaminated clothing, clothing, crates, and other equipment. Insects and shoes, tires, etc. Birds that recover should be consid- rodents may mechanically carry the virus from ered carriers for life. LT may be harbored in speciality infected to susceptible poultry. poultry such as exhibition birds and game fowl. Infectious Coryza/ roup: Chickens, pheasants, Chlamydiosis/ ornithosis/ psittacosis/ parrot and guinea fowl. Common in game chicken flocks. fever: The disease was called psittacosis or parrot Swelling around the face, foul smelling, thick, sticky fever when diagnosed in psittacine (curve-beaked) discharge from the nostrils and eyes, labored birds, and called ornithosis when diagnosed in all breathing, and rales (rattles - an abnormal breathing other birds or in humans. Currently, the term sound) are common clinical signs. The eyelids are chlamydiosis is used to describe infections in any irritated and may stick together. The birds may have animal. Affected species include turkeys, pigeons, diarrhea and growing birds may become stunted. ducks, psittacine (curve-beaked) birds, captive and Mortality from coryza is usually low, but infections aviary birds, many other bird species, and other can decrease egg production and increase the animals. Chickens are not commonly affected. incidence and/or severity of other diseases. Mortality Humans are susceptible, especially older and can be as high as 50 percent, but is usually no more immunosuppressed individuals who are at a higher than 20 percent. The clinical disease can last from a risk. Chlamydiosis in humans is an occupational few days to 2-3 months, depending on the virulence disease of turkey growers, haulers, and processing of the pathogen and the existence of other infections workers in the live-bird areas and of workers in pet- such as mycoplasmosis. bird aviaries although the incidence is rare. Clinical Veterinary World . www.veterinaryworld.org . Vol.1, No.7,signs July 2008 218 Common Respiratory Diseases of Poultry in most birds include nasal-ocular discharge, reluctance to move, swollen joints, stilted gait, loss conjunctivitis, sinusitis, diarrhea, weakness, loss of of weight, and formation of breast blisters. Birds body weight, and a reduction in feed consumption. infected with the respiratory form exhibit respiratory In turkeys there is also respiratory distress and loose distress. Greenish diarrhea is common in dying birds. yellow to greenish-yellow colored droppings. Clinically, the disease in indistinguishable from MG. Chylamydiosis runs rather slowly through turkey MS is transmitted from infected breeder to flocks, with a maximum incidence of around 50%. progeny via the egg. Within a flock, MS is spread by The primary means of transmission is through direct contact with infected birds as well as through inhalation of fecal dust and respiratory tract airborne particles over short distances. secretions. It can also be transmitted on Mycoplasma meleagridis (MM), N strain, H contaminated clothing and equipment. Recovered strain: MM affects turkeys of all ages, although birds remain carriers and will continue to poults are affected more severely than mature intermittently shed the infective agent for long turkeys. Recently, MM has been shown to infect periods after clinical signs have subsided. pigeon, quail and peafowl. A drop-off in production Environmental stress may provoke a reoccurrence and hatchability can be expected in breeder flocks. of the disease. There can be very high mortality in young poults. Mycoplasma gallisepticum (MG), chronic Unthriftiness, respiratory distress, stunting, crooked respiratory disease (CRD), infectious sinusitis, neck with deformity of cervical vertebrae, and leg mycoplasmosis: Chickens, turkeys, pigeons, ducks, deformation are common in young birds. peafowl and passerine birds. Clinical symptoms vary Egg transmission is low in the early breeding slightly between species. Infected adult chickens may period, but rises as the the age of the flock increases. show no outward signs if infection is uncomplicated. Infections can be introduced into a flock by However, sticky, serous exudate from nostrils, foamy contaminated equipment, shoes, exudate in eyes, and swollen sinuses can occur, Aspergillosis/ brooder pneumonia/ mycotic especially in broilers. The air sacs may become pneumonia: When the source of the disease is the infected. Infected birds can develop respiratory rales hatchery, the disease is called brooder pneumonia. and sneeze. Affected birds are often stunted and In older birds, the disease is called aspergillosis. All unthrifty. birds (domestic poultry, pigeons, canary and zoo bird There are two forms of this disease in the species), animals, humans, and plants are turkey. With the “upper form” the birds have watery susceptible. eyes and nostrils, the infraorbitals (just below the Aspergillosis occurs as an acute disease of eye) become swollen, and the exudate becomes young birds and a chronic disease in mature birds. caseous and firm. The birds have respiratory rales and show unthriftiness. With the “lower form”, Young birds have trouble breathing and gasp for air. infected turkeys develop airsacculitis. As with Characteristically, there are no rales or respiratory chickens, birds can show no outward signs if the sounds associated with aspergillosis. Feed consumption decreases. Occasionally there is infection is uncomplicated. Thus, the condition may go unnoticed until the birds are slaughtered and the paralysis or convulsions caused by the fungal toxin. typical legions are seen. Birds with airsacculitis are Mortality in young birds averages 5-20 percent, but condemned. may be as high as 50 percent. Mature birds also MG in chicken embryos can cause dwarfing, have respiratory distress, reduced feed consumption, airsacculitis, and death. MG can be spread to and may have a bluish and dark color of the skin offspring through the egg. Most commercial breeding (cyanosis). Nervous disorders, such as twisted flocks, however, are MG-free. Introduction of infected necks, may occur in a few birds. Mortality in mature replacement birds can introduce the disease to MG- birds is usually less than 5 percent. Aspergillosis is negative flocks. MG can also be spread by using caused by a fungus. The fungus grows well at room MG-contaminated equipment. temperature and higher. All litter and nest materials Mycoplasma synoviae (MS), infectious synovitis, (peat moss, peanut hulls, sawdust, peat, bark, straw) synovitis, silent air sac: Chickens and turkey are have been known to have been contaminated with commonly affected. Birds infected with the synovitis aspergillus. Feed and water should be suspect when form show lameness, followed by lethargy, attempting to identify the source of contamination. Please visit our journal website www.veterinaryworld.org Veterinary World . www.veterinaryworld.org . Vol.1, No.7, July 2008 219