Bovine Herpesvirus type 1
Infectious bovine rhinotracheitis virus, Infectious pustular vulvovaginitis, and associated diseasesInfectious bovine rhinotracheitis is caused by BOVINE HERPESVIRUS 1. Often presents as respiratory disease but cows that had no respiratory signs can abort. Conjunctival signs of IBR infection can present with no respiratory signs or abortions. Corneal opacities start peripherally. Young calves can develop a generalized disease due to Infectious Bovine Rhinotracheitis.Infectious pustular vulvovaginitis is the genital form of IBR infection caused by HERPESVIRUS 1, type 2b. Main lesions are small papules and pustules on the mucosa of the vulva and vagina in females and the penis in males. Usually but not always seen without concurrent respiratory disease.
The incubation period for the respiratory and genital forms is 2-6 days. In the respiratory form, clinical signs range from mild to severe, depending on the presence of secondary bacterial pneumonia. Clinical signs include high fever, anorexia, coughing, excessive salivation, nasal discharge that progresses from serous to mucopurulent, conjunctivitis with lacrimal discharge, inflamed nares (hence the common name ‘red nose’), and dyspnea if the larynx becomes occluded with purulent material. Nasal lesions consist of numerous clusters of grayish necrotic foci on the mucous membrane of the septal mucosa, just visible inside the external nares. They may later be accompanied by pseudodiphtheritic yellowish plaques. Conjunctivitis with corneal opacity may occur as the only manifestation of BHV-1 infection. In the absence of bacterial pneumonia, recovery generally occurs 4-5 days after the onset of signs.
Abortions may occur concurrently with respiratory disease but may be seen up to 100 days after infection. They can occur regardless of the severity of disease in the dam. Abortions generally occur during the second half of pregnancy, but early embryonic death is possible. In genital infections, the first signs are frequent urination, elevation of the tailhead, and a mild vaginal discharge. The vulva is swollen, and small papules, then erosions and ulcers, are present on the mucosal surface. If secondary bacterial infections do not occur, animals recover in 10-14 days. With bacterial infection, there may be inflammation of the uterus and transient infertility, with purulent vaginal discharge for several weeks. In bulls, similar lesions occur on the penis and prepuce. (See also Vulvitis And Vaginitis In Large Animals) BHV-1 infection can be severe in young calves and cause a generalized disease. Pyrexia, ocular and nasal discharges, respiratory distress, diarrhea, incoordination, and eventually convulsions and death may occur in a short period after generalized viral infection
Uncomplicated BHV-1 infections can be diagnosed based on the characteristic signs and lesions. However, because the severity of disease can vary, it is best to differentiate BHV-1 from other viral infections by viral isolation. Samples should be taken early in the disease, and a diagnosis should be possible in 2-3 days. A rise in serum antibody titer also can be used to confirm a diagnosis. It is not possible to detect a rising antibody titer in abortions, because infection generally occurs a considerable length of time before the abortion, and titers are already maximal. BHV-1 abortion can be diagnosed by identifying characteristic lesions and demonstrating the virus in fetal tissues by virus isolation, immunoperoxidase, or fluorescent antibody staining. Gross and microscopic lesions detected shortly after death may help to establish a diagnosis.