Infectious Bovine Rhinotracheitis

Introduction

This disease is also known as IBR  and is caused by Bovine Herpesvirus 1 through aerosol transmission and close contct of infected animals. It is a highly infectious disease of cattle, causing upper respiratory tract disease. The virus is a herpesvirus, meaning it has the ability to lie latent for a long period of time until reactivated by stress.

BHV-1 infects the respiratory mucosal epithelial cells (intranuclear inclusion eosinophilic inclusion bodies)from nasal mucosa down to bronchioles, which leads to neutrophilic inflammation of varying severity.

Clinical Signs

Depending on severity, one will see serous, catarrhal or purulent nasal discharge, sneezing, coughing, dyspnoea and anorexia. There will be a rhinotracheitis that can develop into bronchopneumonia. An increased respiratory rate will also be present. Pregnant cows will also be seen to abort at 5 months or later in gestation.

Clinical disease most severe in young calves, which can develop mucosal ulcerative lesions in the oesophagus and forestomachs and viraemia with multiorgan infection. 

There is generally a high morbidity with low mortality, but up to 75% mortality if concurrent with BVDV, caused by meningo-encephalitis. Signs can be made more severe by secondary bacterial infection such as Pasturella or Mycoplasma.

Diagnosis

Clinical signs are suggestive. Definitive diagnosis can be achieved by virus isolation and immunofluorescence.

On microscopic examination of infected tissue, one will see intrnuclear inclusion bodies, which are indicative of the virus.

Control

Vaccination is avaliable and commonly used in the UK. Both vaccines avaliable in the UK are given intranasally and neither protect against re-infection when given during clinical outbreak, but can lessen the severity of the disease. There are also Inactivated vaccines: intranasal/intramuscular administration, which have a gE deletion making this a marker vaccine. There is an ELISA for gE deletion, which can enable culling of carrier animals. IPV has mostly been made obsolete by AI

References

IBR in nasal cavity (Image sourced from Bristol Biomed Image Archive with permission)

IBR in trachea (Image sourced from Bristol Biomed Image Archive with permission)

Andrews, A.H, Blowey, R.W, Boyd, H and Eddy, R.G. (2004) Bovine Medicine (Second edition), Blackwell Publishing
Divers, T.J. and Peek, S.F. (2008) Rebhun's diseases of dairy cattle Elsevier Health Scieneces
Radostits, O.M, Arundel, J.H, and Gay, C.C. (2000) Veterinary Medicine: a textbook of the diseases of cattle, sheep, pigs, goats and horses Elsevier Health Sciences