Adult diarrhea Flashcards
What age group is unlikely to experience diarrhea and why
3 week to 6 month old ruminants- passed neonatal period and now have maternal antibody
What is the most common cause of diarrhea in 3 week to 6 month old ruminants?
Coccidiosis
What is the most common cause of acute diarrhea in adult ruminants?
Simple indigestion
Describe the symptoms of simple indigestion
Decrease in appetite and milk production, rumen hypomotility, mild bloat, abnormal feces, generally signs are mild and multiple animals are affected
How do you diagnose simple indigestion?
Rule out other causes of acute diarrhea, perform rumen fluid analysis (change in color/consistency/pH), look at management
What proportion of BVD isolates are non-cytopathic?
> 90%
How do cytopathic and non-cytopathic strains of BVD differ?
Cytopathic cause degenerative lesions, noncytopathic strains do not
Which genotype of BVD has been associated with recent outbreaks of severe acute disease?
Genotype 2
Describe the pathophysiology of BVD
Spreads mainly through direct contact with secretions of viremic animals; naive animal is exposed -> virus is taken up by reticuloendothelial cells in spleen and lymph nodes -> replicates within lymphocytes and macrophages and viremia occurs -> virus colonizes GI, respiratory, and reproductive tracts -> virus shed for up to 10 days
What are the clinical signs and sequella of BVD infection?
Can be asymptomatic or mild symptoms with diarrhea, fever, decreased feed intake, decreased milk production, oral erosions. Main complications are immunosupprsesion, fetal disease/death, and hemorrhage.
Describe immunosuppression from BVD
Immunosuppression lasts about 3 weeks, due to transient leukopenia and lymphopenia with altered T and B cell, neutrophil, monocyte, and macrophage function
Makes animals particularly susceptible for respiratory disease
Describe hemorrhage from BVD
Some strains of BVD can cause marked thrombocytopenia, may see petechia and ecchymoses, bleeding from injection sites, bloody diarrhea, epistaxis
Platelet production is not decreased so thrombocytopenia is due to destruction/sequestration
When does a cow need to be exposed to BVD to cause reproductive failure?
Within first 100 days of gestation
What might you see in fetuses from cows infected with BVD in the first 100 days of gestation?
Abortion, mummification, or infertility of cow
When does a cow need to be exposed to BVD for it to cause congenital defects in the fetus?
60 to 180 days of gestation
What congenital defects can be caused by BVD?
Cerebellar hypoplasia, ocular abnormalities, musculoskeletal abnormalities, skin/haircoat deformities
When do cows need to be infected with BVD for the calf to become persistently infected?
Before 125 days of gestation
Describe the process of an animal becoming persistently infected
Dam becomes infected in first 125 days of gestation, fetus develops permanent immunologic tolerance to that strain of BVD and sees it as “self”, calves may be “poor doers” but can appear normal, if they reproduce their offspring will be persistently infected
After what day of gestation will infection with BVD cause a normal calf that is seropositive?
Day 180
How is acute BVD diagnosed?
IFA, virus isolation from buffy coat, serology (4 fold rise in AB titer over 4 weeks), necropsy with depletion of lymphocytes in Peyer’s patches and lymph nodes and erosions in oral cavity and/or GI tract
How is chronic BVD diagnosed?
Virus isolation (2 positive tests 3-4w apart), ELISA assays, group screening with pooled PCR of serum or milk, skin biopsies stained for monoclonal antibodies or used for antigen ELISA assay
How is BVD treated?
No specific treatment, supportive care with fluids and antibiotics for secondary infections
PI animals should be culled when identified
How is BVD controlled?
Identification of PI animals, test incoming animals, vaccinate at least one month before breeding with MLV, vaccinate calves at <6 months and booster after 6 months of age
What are the disadvantages of MLVs for BVD?
Cause transient immunosuppression and viremia, can cause abortion
What conditions are required for mucosal disease to develop from BVD?
Fetus is exposed in utero to non-cytopathic strain at <125 days
Calf must then later be exposed to antigenically similar cytopathic strain
Calf cannot mount an immune response against the cytopathic strain, so severe cytopathic lesions develop
Describe the progression of mucosal disease from BVD?
Acute fever, anorexia, depression, mucosal erosions, hypersalivation, profuse diarrhea, coronary band erosions and skin erosions. Progresses quickly and almost always fatal in 5-7 days.
