Bovine viral diarrhea

From Cow
In BVD, the large intestine congestion takes on a ‘tiger stripe’ pattern following the normal folds of the internal surface of the colon
Chronic BVD cases shows presence of elevated, yellow, friable plaques in the gastrointestinal tract, especially the tongue and the rumen

Bovine viral diarrhea and mucosal disease complex (BVD) is a viral disease caused by a pestivirus (BVDV) that affects mostly young cattle worldwide.

Cause

Bovine viral diarrheal virus (BVDV) is spread by insects and fomites and primarily affects cattle but can affect other ruminants. BVDV can spread via direct or indirect contact and can be isolated in and is widely disseminated by nasal discharge, saliva, feces, semen, urine, tears and milk of persistently infected animals[1].

Classically, isolates of BVDV are separated into noncytopathic and cytopathic biotypes based on cytopathic effects observed in infected cultures of non-lymphoid cells. There are at least 2 viral genotypes (distinct genetic groups) of BVDV that can be further divided into subgenotypes or genogroups. The viral genotypes are termed BVDV type 1 and BVDV type 2, and both cytopathic and noncytopathic BVDV are represented in each viral genotype[2].

Clinical signs

Clinical signs include fever, inappetence, diarrhea, ptyalism, reduced milk production, oral ulcers and mucosal lesions[3]. High morbidity with moderate mortality is common and coinfection with the fungus Enterocytozoon spp is frequently noted.

In pregnant cattle, embryonic resorption, abortion, stillbirths and congenital malformations such as testicular hypoplasia, microphthalmos and CNS involvement have been reported.

Clinical signs may last several weeks to months.

Diagnosis

BVD is diagnosed tentatively from disease history, clinical signs, and gross and microscopic lesions. Confirmation is obtained with ELISA or PCR testing of infective tissue samples. Immunohistochemistry testing has also proved effective.

A differential diagnosis would include Rinderpest and Malignant catarrhal fever.

Treatment

Treatment of BVD remains limited primarily to supportive therapy.

Control is based on sound management practices that include use of biosecurity measures, elimination of persistently infected cattle, and vaccination[4].

Inactivated and modified live virus vaccines are available[5] and show good efficacy at preventing disease transmission in at-risk herds[6].

A potential risk has been reported about calves developing neonatal pancytopenia as a consequence of ingesting colostrum from BVD-vaccinated cows[7].

References

  1. Campbell, JR (2004) Effect of bovine diarrhea virus in the feedlot. Vet Clin North Am Food Anim Pract 20(1):39-50
  2. Merck Vet Manual
  3. Baker, JC (1995) The clinical manifestations of bovine viral diarrhea infection. Vet Clin North Am Food Anim Pract 13(3):425-454
  4. Brook, KV (2004) Strategies for the control and prevention of bovine viral diarrhea virus. Vet Clin Food Anim 20:171-180
  5. Kelling CL (2004) Evolution of Bovine Viral Diarrhea Virus Vaccines. Veterinary Clinics Food Animal Practice 20:115-129
  6. Givens MD et al (2012) Protective effects against abortion and fetal infection following exposure to bovine viral diarrhea virus and bovine herpesvirus 1 during pregnancy in beef heifers that received two doses of a multivalent modified-live virus vaccine prior to breeding. J Am Vet Med Assoc 241(4):484-495
  7. Cooper C (2012) Potential link between the development of a bleeding syndrome in young calves and the consumption of colostrum from cows vaccinated with a killed bovine viral diarrhea vaccine. Can Vet J 53(2):143