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→Clinical Signs
== Clinical Signs ==
== Clinical Signs ==
Signs of IBR include '''coughing, serous nasal discharge, tachypnoea and dyspnoea'''. There may also be signs of increased lacrimation and a '''marked conjunctivitis'''. Coughing and sneezing are observed. The virus is excreted in the nasal secretions as early as 24 hours after infection. After an incubation period of 2 to 4 days, nasal secretions are more profuse and evolve from '''sero-mucous to mucopurulent discharge'''. The animal will usually be '''pyrexic''' and be weak, dull and depressed. It will usually have a reduced appetite and may show signs of weight loss. If in milk, the yield will be decreased. Young animals show ptyalism.
Signs of IBR are variable but classically include '''coughing, serous nasal discharge, tachypnoea and dyspnoea'''. There may also be signs of increased '''lacrimation''' and a '''marked conjunctivitis'''. Coughing and sneezing are observed. The virus is excreted in the nasal secretions as early as 24 hours after infection. After an incubation period of 2 to 4 days, nasal secretions are more profuse and evolve from '''sero-mucous to mucopurulent discharge'''. The animal will usually be '''pyrexic''' and be weak, dull and depressed. It will usually have a reduced appetite and may show signs of weight loss. If in milk, the yield will be decreased. Young animals show ptyalism. In endemic dairy herds, it is not uncommon for animals to present with '''milk drop''' with or without pyrexia.
IBR may cause '''abortion''' if susceptible cows or heifers are infected during pregnancy. Abortion is observed between '''4 and 8 months of gestation'''. Early embryonic death can also occur. Abortion is a consequence of '''respiratory infection of pregnant cows'''. Viraemia allows the virus to enter the uterine artery and cross the placenta. Abortion is due to a '''lytic infection''' of the fetus. All internal organs of the fetus, especially the '''liver and renal cortex''', show foci of necrosis. A generalized multifocal necrosis is diagnosed.<ref> Smith, K. C (1997) '''Herpesviral abortion in domestic animals'''. ''Vet Journal'', 153(3):253-268</ref> Infection of cows during the last trimester of gestation can lead to '''neonatal death''', and death of weak calves can occur during the first 2 weeks of life.<ref> Thiry, E., Detilleux, P., Vriese, A., Pirak, M., Pastoret, P-P (1984) '''Infectious bovine rhinotracheitis in the neonatal period: a review and a case report.''' ''Annales de Médecine Vétérinaire'', 128(1):33-40; 25</ref>
IBR may cause '''abortion''' if susceptible cows or heifers are infected during pregnancy. Abortion is usually observed between '''4 and 8 months of gestation'''. Early embryonic death can also occur. Abortion is a consequence of '''respiratory infection of pregnant cows'''. Viraemia allows the virus to enter the uterine artery and cross the placenta. Abortion is due to a '''lytic infection''' of the fetus. All internal organs of the fetus, especially the '''liver and renal cortex''', show foci of necrosis. A generalized multifocal necrosis is diagnosed.<ref> Smith, K. C (1997) '''Herpesviral abortion in domestic animals'''. ''Vet Journal'', 153(3):253-268</ref> Infection of cows during the last trimester of gestation can lead to '''neonatal death''', and death of weak calves can occur during the first 2 weeks of life.<ref> Thiry, E., Detilleux, P., Vriese, A., Pirak, M., Pastoret, P-P (1984) '''Infectious bovine rhinotracheitis in the neonatal period: a review and a case report.''' ''Annales de Médecine Vétérinaire'', 128(1):33-40; 25</ref>
'''Latent infection can occur''', the viral cells residing in the '''trigeminal nerve''', and infected cattle can then shed the virus intermittently.
'''Latent infection can occur''', the viral cells residing in the '''trigeminal nerve''', and infected cattle can then shed the virus intermittently.
Other animals recover within 14 days, due to the rise of the specific immune response. Some highly virulent BHV-1 strains induce a high mortality rate.
Other animals recover within 14 days, due to the rise of the specific immune response. Becoming latent is a common sequelae to infection and in terms of control, all animals on an endemic farm should be considered as potential latent carriers irrespective of their antibody status. Some highly virulent BHV-1 strains induce a high mortality rate.
In IPV, signs will include '''pain of the vagina or penis''' and erythrematous swelling of this region, reluctance to mate, mucous discharge from the vulva or penis and signs of '''ulcers, vesicles and erosions''' on the penis or vagina. The animal may urinate frequently and have an elevated tail.
In IPV, signs will include '''pain of the vagina or penis''' and erythrematous swelling of this region, reluctance to mate, mucous discharge from the vulva or penis and signs of '''ulcers, vesicles and erosions''' on the penis or vagina. The animal may urinate frequently and have an elevated tail.
== Pathology ==
== Pathology ==