AVIAN RHINOTRACHEITIS (ART) – A SAFE AND EFFECTIVE POULTRY FARMING SOLUTION

1. Cause of disease
Swollen Head Syndrome – ART (Avian Rhinotracheitis) is essentially a newly emerging upper respiratory tract infection. However, its clinical signs and lesions are mainly concentrated in the head region, which is why it is commonly referred to as Swollen Head Syndrome caused by Avian Pneumovirus (APV).
APV is the abbreviation for a type of Avian Pneumovirus, which belongs to the subfamily Pneumoviridae, within the Paramyxoviridae family. It is divided into two branches. The Pneumovirus branch causes respiratory diseases in mammals and often forms syncytia (multinucleated giant cells), while the Metapneumovirus branch causes respiratory diseases in chickens and poultry. This virus is known as Avian Metapneumovirus, abbreviated as AMPV or APV, and does not form syncytia.
APV causes rhinitis and tracheitis in turkeys, commonly referred to as Turkey Rhinotracheitis (TRT). In chickens and other poultry, rhinitis and tracheitis caused by APV are known as Avian Rhinotracheitis (ART). This condition is often complicated by superinfection with E.coli bacteria, leading to the development of Swollen Head Syndrome (SHS).
In Vietnam, research conducted by Le Van Nam and colleagues during 2019–2020 focused on ART caused by APV. The disease was found to affect chickens of all ages, with a morbidity rate of up to 100% within affected flocks. If left untreated, the mortality rate reached 77.7%, egg production decreased by 73%, and meat yield decreased by 32%.
2. Epidemiology of the disease
- Although the disease spreads very rapidly, it is primarily transmitted through direct contact, respiratory routes, or oral routes (through eating or drinking).
- The disease occurs in poultry of all ages, and there is no evidence of vertical transmission from breeder poultry to offspring. It is not seasonal but rather depends on hygiene conditions, management practices, and especially the microclimate of the poultry house.
3. Symptom
The incubation period depends on the APV strain, ranging from 1 to 14 days, though some flocks have shown symptoms as late as 21 days after infection.
3.1. Acute form 
Turkeys are the most susceptible, followed by chickens and commercially raised poultry.
*For chickens in the growing stage
Sneezing, runny nose, head shaking, and beak flicking. Due to eye irritation, chickens often scratch their eyelids with their feet. Watery eyes and nose, with air bubbles in tears, and snot, are signs of the early stage of the disease. Chickens may show head tremors, fatigue, and reduced appetite.
Rapid breathing and shortness of breath accompanied by a distinct wheezing sound deep in the trachea. Chickens may experience suffocation if tracheal secretions become caseinization and cannot be expelled.
The chicken's face begins to swell, the eyelids become inflamed and puffy, the eyes appear half-closed. The conjunctiva becomes necrotically inflamed, sticky and foamy — a characteristic sign of a swollen head caused by Avian Pneumovirus (APV). If conjunctivitis is not treated promptly, the inflammation may penetrate the pupil, leading to blindness. Initially, only one eye may be affected, but later both eyes become inflamed, swollen, decayed, and eventually blind, the chickens could not eat so many died.
*For laying hens
Symptoms are similar to those seen in growing chickens but with additional signs such as decreased egg production, different egg sizes, soft-shelled, immature and deformed eggs. In breeder flocks, there is a reduction in the proportion of hatchable eggs, lower embryo viability, increased embryo mortality, and decreased hatchability rates.
In practice, when a flock is infected with Avian Rhinotracheitis (ART) caused by Avian Pneumovirus (APV), superinfection with bacteria such as E. coli causing Swollen Head Syndrome (SHS); Mycoplasma causing asthma and swollen head; ORT causing rhinitis, tracheitis and swollen head; Infectious Coryza (IC)making it difficult to diagnose the disease. In the opposite case, ART can also be a secondary disease following infections such as CRD, IB, ILT, IC, ORT. In these cases, the clinical signs and lesions are more diverse, making it difficult to distinguish between the primary and secondary diseases.
3.2. Subacute form
This is the disease caused by APV strains with medium virulence and often appears in farms with good biosecurity, or as a progression from the acute form.
 
The symptoms are milder compared to the acute form; however, susceptible to superinfection with opportunistic bacteria such as E. coli, Haemophilus, Mycoplasma, ORT, etc.
3.3. Chronic or carrier form
Usually, the chronic carrier form is the result of incomplete treatment of the acute and subacute forms and after treatment, the APV remains in the chicken's body for a long time until it encounters harmful stress factors, the health of the poultry declines, and the disease recurs. The disease occurs slowly, the incidence is low so it is often not detected, leading to treatment failure, and making the disease worse.
The main symptoms include: itchy eyes, watery eyes, nasal with air bubbles, swollen eyelids, blindness, shortness of breath with wheezing and rattling sounds in the trachea, frequent head shaking and phlegm expulsion… In laying hens, there are signs of reduced fertility.
4. Lesions
Pathological lesions of ART caused by APV are mainly concentrated in the head, respiratory and reproductive organs, independent of the disease type but also depending on the stage of disease development, including the following changes:
 One or both sides of the head become edema, and the chicken exhibits excessive tearing and nasal discharge. The presence of air bubbles in the tears and nasal mucus is the first symptom. The eyelids are inflamed and swollen, the eyes become sticky, with both eyelids sticking together. The pupils may bulge, and the eyes appear closed or tightly swollen. When the eyelids are gently opened, foamy conjunctivitis is visible, showing signs of necrosis, which leads to varying degrees of blindness during different stages of the disease.
Peeling the skin of the cheek, head and neck reveals evident inflammation with thick yellow mucus exudate, forming a dense yellowish tissue layer located just beneath the skin. This is the second characteristic lesion of ART caused by APV.
Mucohemorrhagic tracheitis is the third characteristic lesion: the nasal mucus caused by APV rapidly undergoes fibrinization and caseinization transformation, forming yellow-brown or yellow-white-red plaques with air bubbles, scattered along the tracheal lumen. This presentation is distinct from lesions caused by IB, ILT, or ORT.
The lungs show inflammation with mucus and transudate, containing large amounts of yellow-brown transudate, leading to pulmonary edema. When the lungs are cut in halves or thirds and placed in water, it is sink.
The ovaries are inflamed, hemorrhagic, and necrotic, with numerous degenerated, atrophied, rotten, or deformed immature follicles. The oviduct is thinned, shortened, and shows signs of inflammation, degeneration, and necrosis. In some cases, the oviduct is hyperplastic, thickened, firmer than normal, and still shorter than usual. Many eggs are retained in the oviduct due to the hen’s inability to lay. As a result, egg production declines, and many eggs have soft shells, different sizes, and pale colors that differ significantly from normal eggs.
 

5. Diagnose
- Differential diagnosis with IC, ORT, ILT, IB, Newcastle, AI, CRD, CCRD, E. coli, ...
6. Prevention
6.1. Biosafety control
- Implement biosecurity measures in poultry farming to ensure that the housing environment is always dry, well-ventilated and clean.
- Use one of the disinfectants such as Five-BGF, Five-B.K.G, Five-Perkon 3S and apply by spraying once a week on a regular schedule.
6.2. Phòng bệnh/ Prevention 
- Periodically vaccinate against chicken diseases Five-Gumboro, Five-AI (H5N1, H5N6), Five-Newcastle (G7), Five-Fowl Pox, Five-ND.IB.EDS,... Especially against ART disease: vaccinate broilers with APV at 2 - 3 weeks of age. For laying hens, vaccination should be repeated at 56 days of age and 15 - 16 weeks of age before the chickens lay eggs.
7. Treatment
* Step 1: Administer a booster dose of the APV vaccine via eye drops
 * Step 2: Use medication to treat symptoms and secondary infections. Use one of the following medications: Five-Amoxcin super, TW5-Amox.600, TW5-Doxy.500, Five-Tylvasin, Five-Doxyl 750, Five-Tilmo Super Oral,... Dosage and treatment regimen according to instructions on the product packaging.

* Step 3: Increase chicken resistance with one of the following medicines:
- Supplements: Five-Bromhexin inject, Five-Extra Oil, Five-Chymosin,…
- Liver and kidney detoxification: Five-Bogama, Five-Orgamin, Five-Phosric,…
 - Enhance resistance: Beta-Glucan C, Five-Vitamin C, Five-Aminovit Super, … dosage and administration as per instructions.
Combined with proper care and nutrition, maintain clean and well-ventilated housing for the sick flock.