BVD is a(n) ___________ virus.
BVD infects ____________ [cell type]; it has a tropism for the...
immune cells; viral receptors on lymphocytes and monocytes.
What are the modes of transmission of BVD? (8)
shed in oral, nasal secretions, feces, urine, semen, biting insects, trans-placentally, iatrogenically
What are implications for vaccination of a calf nursing on a pregnant dam and BVD?
if you vaccinate the calf with a MLV, the dam and fetus can be infected--> abortion, cerebellar hypoplasia, PI calf
What are the BVD clinical syndromes? (7)
acute BVD, persistent infection, mucosal disease (when PI is vaccinated with MLV), reproductive problems, thrombocytopenia/ bleeders, immunosuppression, respiratory disease
How does a calf become a PI?
when infected in-utero at around 120 days gestation b/c their immune system doesn't recognize it as foreign and it becomes self-antigen; must be infected with a non-cytopathic strain
What are clinical signs of BVD in acute infection?
fever, depression, diarrhea, oral/ esophageal/ abomasal ulcers, +/- lameness with coronary ulcerations; clinical course 7-10 days
In what cattle is acute BVD usually seen?
less than 2 years old
Describe the cause of mucosal disease associated with BVD.
when a PI calf (infected with ncp strain) is exposed to a cytopathic strain or their ncp strain mutates to a cp strain
What are the signs of mucosal disease associated with BVD? (5)
[amplified from acute BVD] severe explosive diarrhea, GI ulceration from muzzle to colon, necrosis of peyer's patches, high fever, mortality 100%
Describe the course of BVD PI disease.
more susceptible to respiratory and GI infections and are treated for recurring disease; if exposed to cp strain or gets vaccinated, mucosal disease and death
Describe results of infection with BVD at different stages of gestation.
- <100 days--> abortion
- 100-120 days--> PI calf
- >120 days--> cerebellar hypoplasia, arthrogryopsis, etc
What reproductive problems can result form infection with BVD? (6)
- abortion and poor conception
- infection during middle trimester--> cerebellar hypoplasia, micro-ophthalamia, cataracts, retinopathy with pigmentation
What causes thrombocytopenia/ bleeders with BVD?
infection with Type II BVD
What are signs of BVD-associated thrombocytopenia? (5)
spontaneous hemorrhages along the GI tract, sclera, at injection sites, death of adults and young, platelet counts <10k
What pathologic lesions are associated with BVD? (5)
erosions of palate, gums, and under tongue, linear esophageal erosions, abomasal/ ruminal ulcers, peyer's patch necrosis, +/- secondary pneumonia
How is BVD diagnosed? (5)
- virus isolation from blood, feces, areas of erosion
- serology- virus neutralization with 1 samples 10-14 days apart
- PCR on blood, fluids, tissue
- antigen capture ELISA of blood or tissue
- immunohistochemistry of collected tissue
What are the pros and cons to using a killed BVD vaccine?
- Pros: safe to use at any stage of pregnancy
- Cons: must be administered twice initially and boostered all the damn time, mainly stimulates only humoral immunity
What are the pros and cons to the MLV BVD vaccine?
- Pros: superior immunity (cell mediated and humoral immunity), single injection
- Cons: may cause abortion if used in early to mid gestation
Describe the characteristics of the etiologic agent of Johne's disease.
- Mycobacterium avium ss. paratuberculosis
- acid-fast, gram + bacteria
What species are hosts to Johne's disease? What are the implications of this?
domestic ruminants and wild/ exotic hoofstock; if your cows are co-mingling with wild deer etc, they may become infected that way (even in a closed, negative herd)
Describe the pathogenesis of Johne's disease.
bacteria in the feces of adults contaminates the environment for the calf, or infective colostrum is administered to calf--> ingested organisms are absorbed and distribute to the intestinal lymph nodes--> slowly multiply in the LN and work back to intestinal mucosa at the ileo-cecal junction--> colonize ileo-cecal LN and travels to SI--> granulomatous reaction in intestinal wall--> poor water absorption, PLE
____________ in milk and colostrum can carry Johne's organisms, serving as a source of transmission of infection.
Macrophages (can resist lysosome within macs/ lymphs)
Infections with Johne's most likely occur at __________[age].
6-8 months old, but most within first 30 days
Infection with Johne's causes a(n) ____________ in the intestinal wall, leading to... (2)
granulomatous reaction; poor absorption of water, loss of proteins (albumin) into gut lumen.
Infection with Johne's primarily affect the _________ in cattle and the _________ in small ruminants.
large intestine; small intestine
What is the recommendation for dealing with Johne's on a farm?
eliminate all offspring of infected dams to minimize maintenance of the disease within the herd
What are clinical signs of Johne's? (5)
normal appetite, chronic wasting, chronic diarrhea, hypoproteinemia, submandibular edema (bottle jaw)
Johne's cow develop clinical signs at __________[age].
>2 years old
How is Johne's diagnosed? (4)
- fecal culture with specialized media- mycobactin J for growth, brother cultures are faster
- serologic tests- AGID, ELISA
- DNA probe of feces
- Histopathology- biospy or necropsy (acid fast organisms)
Describe the control and prevention of Johne's. (6)
- strict sanitation, remove calves at birth/ do not let nurse dam, clean udder before nursing (beef)
- herd testing with fecal culture and serologic testing
- don't spread manure on fields (bacteria live in manure >1yr)
- don't buy animals from unknown sources, embryo recipients
- consider vaccination in high prevalence herds (need state vet approval, must be tested for bovine TB first)
- monensin to keep cows (shedding decreases but doesn't go away)
Describe the use of the different tests for Johne's disease.
- fecal culture + is definitive + (but takes forever), used to establish herd status
- once a herd is established positive, blood ELISAs are more specific
Describe the use of johne's vaccines. (5)
- need approval of state vet
- must test negative for bovine TB first
- only done in positive herds
- done in calves <30 days of age
- predisposes to a granuloma/ abscess in brisket
What causes winter dysentery, and what are characteristics of this disease? (3 characteristics)
- coronavirus ( same as for calf scours)
- immunity to natural infection is short-lived
- causes outbreaks!
- incubation 3-5 days
Clinical signs of winter dysentery. (5)
- explosive outbreak of diarrhea +/- hemorrhage
- normal TPR
- normal appetite
- falling milk production
- severity greater in older cows
How long do clinical signs last with winter dysentery?
How is coronavirus spread?
fecal-oral +/- MAYBE aerosol transmission
How is coronavirus diagnosed? (5)
- EM of feces in acute cases to ID coronavirus
- ELISA and PCR
- clinical signs
- r/o Salmonellosis
How is winter dysentery treatment?
How is Ostertagia acquired?
grazing- L3 on forages
Describe ostertagiasis type II.
winter/ environment not hospitable for parasite--> L4 encyst in abomasal wall--> late winter/ spring--> rapid excystation of parasites--> diarrhea/ disease
What are clinical signs of ostertagiasis type II? (3)
- large volume, watery diarrhea
- bottle jaw- hypoproteinemia/ hypoalbuminemia- intermandibular edema
- normal TPR
When do clinical signs associated with ostertagia type II present? What aged cattle?
- late winter (Feb-April)
- 2-4 year old animals
How can you differentiate Johne's from Ostertagia type II without diagnostic tests?
- Johne's animals are usually older
- Ostertagia occurs the first time these animals are out on pasture
How is Ostetagia diagnosed? (4)
- history and clinical signs
- increased abomasal pH
- plasma pepsinogen >3,000 due to increased pH inhibiting transformation of pepsinogen to pepsin
- McMaster's fecal initially negative b/c larvae are still emerging, plus you can't ID strongyle type eggs... they all look the same (parasitologists larvate eggs and ID adult parasite...we can't do this)
How is ostertagia type II treated and prevented? (5 options)
- Ivermectin, Doramectin, Moxidectin (avermectins macrocyclic lactones)
- Albendazole or Fenbedazole (benzamidazoles)
What gross pathology is seen with type II ostertagiasis?
moroccan leather to abomasal folds
What is the etiologic agent of malignant catarrhal fever? How is it transmitted?
ovine herpesvirus 2; aerosols/ direct contact with young lambs (less than 1 yr of age)
Clinical signs of MCF. (6)
diarrhea, catarrhal nasal exudate, ocular d/c, corneal edema, generalized lymphadenopathy, pneumonia
MCF has _________ morbidity and _________ mortality.
How is MCF diagnosed? (3)
- clinical signs
- histopathology- lymphoid panerteritis, GI ulcerations
- PCR sent to colorado state
What other differentials might you have for an animal with MCF? (5)
BVD, IBR, bluetongue, Rinderpest, foot and mouth
How do you treat MCF?
you can't and they all die
What strains of Salmonella can affect cattle? (3)
- S. dublin (host-adapted)
- S. newport (emerging)
- S. typhimurium (zoonotic)
Clinical signs of Salmonellosis. (5)
diarrhea (maybe watery, maybe bloody), inappetence, down on milk, abortions, +/- fever
What are the clinical lab findings with Salmonellosis?
CBC: initially panpeukopenia an neutropenia; then becomes leukocytosis
Describe transmission of Salmonella.
- feco-oral, direct contact
- stresses cattle can be asymptomatic shedders
- maybe horn flies as potential fomites
Misc causes of diarrhea in adult cows. (4)
copper deficiency, feeding indiscretions, hert failure, renal disease