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Wednesday, June 4, 2014

Infectious balanoposthitis 

Keywords: IPV, IBR, Herpes, bovine, penis

These images show cases of infectious balanapothitis (IBP); one of many manifestations of infection by Bovine Herpes virus type 1. They include  infectious pustular vulvovaginitis (IPV) in females, infectious rhinotracheitis (IBR) and uncommonly, necrotizing meningoencephalitis (the latter is usually caused by Herpes type 5).


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At the outset it was stated that these were cases of IBP but it is not possible to say with certainty if that was so. No attempt was made to grow virus from the lesions and PCR was not performed in either case. This is a common situation because the disease is considered to be ubiquitous and self limiting. Nevertheless, the lesions seen here are typical of those described for the syndrome in bulls. These red vesicles usually become secondarily infected by bacteria, forming small pustules. This can cause reluctance to breed but the lesions are generally considered to benign, healing without treatment. This is very similar to the situation in females, where the syndrome commonly manifests itself as infectious pustular vulvovaginitis (IPV). 

Infectious bovine rhinotracheitis (IBR) is far less benign than either IPV or IBP, characterized by embryonic death, abortions and weak calves. Perhaps obviously, a respiratory syndrome occurs as well.

Interestingly, many bulls that have no history of breeding may show signs of IBP. This is not too surprising in view of the fact that transmission can occur by a number of routes, including airborne infection, fomites, semen and vertical (placental) transmission. Equally interesting have been findings that show that animals with genital infections may shed the virus in nasal secretions without showing respiratory symptoms. Although strain differences do occur, it is intriguing to contemplate how this can occur because numerous studies have shown the virus to be the same in both genital and respiratory syndromes.

In the cases shown here, it is possible that the bulls could be sources of infection throughout their lives because the virus can become latent after the acute phase of the disease. Apparently herpes viruses tend to lie latent in the trigeminal ganglion with shedding occuring in times of stress. Although one could speculate that the virus may lie elsewhere in states of latency, reports cite only the trigeminal ganglion as area for latent virus to reside.

A pertinent question in a case such as this would be: "Can semen from bulls such as these be used to produce embryos that will not transmit IBR/IPV to E.T. recipients and their calves?" This is particularly important when bulls have excellent genetics and international export is contemplated because IBR has been eliminated from several European countries. Although the virus is highly damaging to embryos, those that survive are generally free of herpes virus, even if trypsin is not used in the washing process. However, a small proportion of embryos can still carry virus. Therefore the risk of transmission through ET is considered to be low but potential losses may be too high to contemplate. 

References:
  • Engels, M. et al. 1981 Comparison of the genomes of Infectious Bovine Rhinotracheitis and Infectious Pustular Vulvovaginits virus strains by restriction endonuclease analysis. Archives of Virology 67:169-174
  • Parsonson I.M, 1964 Infectious pustular vulvovaginits in dairy cattle in Victoris. Australian Veterinary Journal 40: 257–260
  • Bielanski A. et al. 2014 Risk of transmission of Bovine Herpesvirus-1 (BHV-1) by infected semen to embryo recipients and offspring Reprod Domestic Anim 49:197–201
  • Rissi D.R. and Barris C.S.L, 2013Necrotizing Meningoencephalitis in a Cow Vet Path 50: 926-929