Bovine & Small Ruminants Abortion Flashcards
What is etiological agent of BVDV?
It is pestivirus that in the bovine species are called Bovine diarrhea virus type 1 (cause classic disease) and bovine diarrhea virus type 2 (cause mucosal disease). This pestivirus is similar to the pestivirus causing the swine classic fever and the pestivirus causing nBorder disease in small ruminants. The bovine diarrhea virus can be classified also according to its ability to cause cellular damage in cytopathogenic and non-cytopathogenic.
How BVDV transmission occurs?
The transmission of BVDV occurs mostly when a susceptible animal enter in contact with body fluids (nasal secretions, saliva, urine, milk, semen), feces, blood, and even aerosol at short distances of persistent infected animal. One hour of contact with a persistent infected calf shedding the virus is enough to a susceptible animal to get contaminated.
What is the clinical presentation of BVDV?
BVDV depending upon virus type can lead to acute or transient infection or the mucosal disease. Most of postnatal infection will be subclinical to the eyes, but close analysis will reveal hyperthermia, leukopenia, thrombocytopenia, and reduced milk production. More evident clinical signs include pyrexia, lethargy, ocular and nasal discharge, occasional pneumonia, oral ulcers, blunting of oral papillae, and diarrhea. If a persistent infected animal is infected with a cytopathic virulent strain it might develop the mucosal diseases that is characterized by severe diarrhea, high fever, emaciation, epithelial erosion at interdigital spaces, coronary bands, oral mucosa, teats, and vulva that can lead to sudden death. If a pregnant is infected the outcome will vary depending upon the stage of pregnancy. Cows pregnant upon to 45 days can have early embryonic losses and reduced fertility. If a cow with is infected with cytopathic infection between 45 and 175 of gestation they might abort, but cows infected with non-cytopathic virus between 70 and 150 might gestate persistent infecte calf. Infection occurring between 100-150 days can result in congenital abnormalities including cerebelar hypoplasia, microencephalopathy, cataracts, microopthamia, and thymus aplasia. Fetus infected between 150-285 days of gestation are able to clear the infection.
In animal infected with BVDV, what is the difference between a transient infected animal and a persistently infected animal?
A transiently infected animal will have virus replicating in tonsils and respiratory tract primarily and subsequently gastrointestinal, tegumentar and respiratory tissues. The majority of transient infection will only have subclinical signs of the disease and within 2 weeks the immune system contain the virus replication and eliminate the infection. If pregnant as discussed before several outcomes might develop. A persistently infected animal is derived from a transiently infected cow that was pregnant between 70 and 150 days or if a persistent infected cows get pregnant. Persistent infected calves might have stunted growth and poor performance and more important will permanently shedding BVDV virus in the environment becoming the main challenge for the control of the disease.
How can BVDV be diagnosed?
BVDV an be diagnosed by immunohistochemistry of blood or ear skin biopsy, or antigen-capture ELISA org ear skin biopsy can be used to detect the virus.
How can BVDV be controlled in a herd?
BVDV control include identification and elimination of persistent infected animals, enhancement of immunity through vaccination to reduce infection and morbidity, improvement of biosecurity to prevent exposure to susceptible cattle. In general, all newborn calves should be tested as soon as possible to prevent exposure to susceptible animals. The dams of PI calves should retested. In herd using a breeding season all calves, replacement heifers, open cows, and breeding bulls should be tested before the beginning for the breeding season.
What is etiological agent of Neosporosis?
Neospora caninum
How the transmission of Neosporosis occurs?
It can transmitted vertically or horizontally. Vertical occurs when the tachyzoites migrate transplacentally from dam to the fetus (Neospora caninum is one of the most efficient transplacentally transmitted parasites). The term endogenous and exogenous transplacental transmission has been used. Endogenous is when a dam that is persistently infected has the parasite crossing the placenta. Exogenous transpalcental transmission occurs when a previously no infected dams get ingests infective oocyst while pregnant and then the fetus gets infected as well. Endogenous has higher abortion rate associated. Vertical transmission can result in abortion, but in most cases the calf is congenitally infected, but assymtomatic. Horizontal transmission is less common than horizontal. Both domestic the domestic and wild dogs are often implicated with dogs releasing sporulated oocyst that generally were acquired after dogs ate placenta contaminated with the parasite.
