Infectious Bovine Rhinotracheitis (IBR)

Syn: Red Nose, Viral bovine rhinotracheitis, Necrotic rhinitis

• It is acute, highly contagious viral disease of cattle and buffaloes characterized by fever, rhinitis, dyspnoea, abortion, meningoencephalitis, keratoconjunctivitis and pustular vulvovaginitis.

Etiology:

• Bovine Herpes Virus-I (BHV-I)
• DNA virus; virus is stable at pH 6.9 and can remain alive for a long period but susceptible to lower pH, ether, acetone, alcohol.
• Virus can be cultivated in cell culture of calf kidney, skin and testis with distinct cytopathological changes.

Epidemiology:

• Disease is widely prevalent in all parts of the world. Disease was first noted in USA
• Disease has been recorded from India, Europe, North America, Africa, Australia, New Zealand
• Seroprevalence of IBR was found to be 16.67 in a study conducted in cattle of Chitwan district in year 2022.
• Cattle of all ages are affected.

Transmission:

• Through infected feeder and waterer
• Through infected food and water
• Virus can be spread through ocular, nasal and reproductive secretion and excretion of the infected cattle.
• Droplet infection is the important way of transmission.
• Venereal transmission possible through AI.
• Cattle recovered from disease may remain as carrier and thus disseminate the virus through their nasal secretions for weeks.
• Virus may remain latent following initial infection.

Pathogenesis:

Virus multiplies in URT

It causes rhinitis, laryngitis and tracheitis

It produces pneumonic changes leading to death of animals

Extends in eye causing conjunctivitis and vascularization of cornea

Enters in brain tissue and produce meningoencephalitis

Changes in placenta, fetus and results in abortion

Clinical Signs:

• Incubation period of disease ranges from 2-6 days.
• Disease is manifested in 5 forms:

1. Respiratory form:

• Fever, depression of appetite/anorexia
• Dyspnoea, serous and nasal discharge followed by muco-purulent discharge.
• Coughing, open mouth breathing
• Red appearance of nasal mucosa
• Rhinitis or necrotic rhinitis
• Bronchitis or pneumonia

2. Vulvo-vaginal form:

• Pustular lesion in vulvar and vaginal mucosa
• Swollen vulva and mucopurulent discharge
• Sharp fall in milk yield
• In case of bull; pustular balanoposthitis, semen contamination and frequent urination

3. Ocular form:

• Conjunctivitis, lacrimation, corneal opacity
• Ocular discharge; serous to purulent

4. Encephalomyelitic form:

• Meningoencephalitis
• High fever, incoordination
• Tremor, circling, coma and death

5. Abortive form:

• Abortion at 4^th month of gestation
• Autolysis of fetus

PM Findings:

• White necrotic lesion on nostril and muzzle
• Erosion of nasal mucosa, hence named ‘red nose’.
• Degenerative and necrotic changes are noted on nasal passage, paranasal sinuses, pharynx, larynx and trachea
• Pustular lesion on mucosa of vulva and vagina
• Fetus may undergo mummification
• Necrotic lesion may appear in liver and spleen of fetus
• Lesion on cerebral cortex.

Diagnosis:

• Based on clinical signs and PM findings
• Isolation and identification of virus
• FAT, SNT or VNT
• ELISA; sandwich indirect ELISA

Differential Diagnosis:

1. Pasteurellosis

• It is caused by Pasteurella multicoda
• Sudden death, brisket edema
• Dyspnea, coughing, gurgling sound

2. BMC fever

• No involvement of lungs, high mortality

3. Allergic rhinitis

• Occurs all on a sudden, dyspnoea
• Respiratory noise, caseous discharge, sneezing
• Ocular discharge

4. Aspiration pneumonia

• Signs of acute bronchopneumonia
• Severe breath sound
• Crackling sound, leukopenia, neutropenia

5. CBPP:

• Deep cough, extension of head and neck
• Abduction of elbow
• Respiratory grunt
• Severe dyspnea

Treatment

• No specific treatment is available. Symptomatic treatment is done.
• Sulpha/Diadin bolus @30 ml/50 kg, b.wt. half dose IV followed by SC, OD for 1^st Then administered @15 ml/50 kg, b.wt. half dose IV followed by SC, OD for 3 days
• Tetracycline LA @1ml/10 kg, b.wt., deep IM, OD, 3-5 days
• Hyperimmune serum may be tried.
• Corticosteroid should never be given.

Control Measures:

• Strict isolation of the affected animals should be made.
• Vaccines; modified live or inactivated vaccine through intranasal. Calves after 5 months of age are vaccinated. Immunity develops within 10-14 days
• Live attenuated vaccines either through intramuscular or intranasal route may be given. In case of outbreak, intranasal will be more helpful.
• Heifers vaccination is advisable 30-60 days before breeding.