Food Ani Med- Cattle- Bovine Resp. Dz Complex 1

drraythe's version from 2016-04-29 15:31


Question Answer
Bovine resp dz complex (BRDC) is akaBRD, shipping fever, penumonia
how common of a problem is BRDC? #1 health problem in beef industry!! annual incidence between 5-40%.
why are cattle predisposed to resp dz?they have greater exposure to pathogens and they use more of their lung capacity for basal breathing
Economic losses associated with BRD result from?decreased production, medication costs, labor costs, & death losses.
BRD is divided into what 3 main categories?(1) Upper resp tract infections (2) diphtheria (3) lower resp tract infections (pneumonia)
what are the problems(CSs) associate with the upper resp tract infection component of BRD?Inflammation of the nasopharyngeal region, pharynx, & Trachea.
Is diphtheria cause of loud insp or expiratory sounds?inspiratory
what is going on (the problems/CSs) with the Diphtheria part of the BRD?Inflammation of the larynx, May occur with UTR and/or pneumonia. Hear Loud inspiratory sounds. Can have death due to asphyxiation.
lower resp infections due to BRD usually occur why? explain mechanismsExtension of URT infection or failure of the innate protective mechanisms: Mucosal Immunity, Mucociliary apparatus
Enzootic pneumonia vs shipping fever: who/age is affected?ENZOOTIC: housed calves (younger, under 1 yr) So young pre-weaned calves around 2-5mo of age. May affect early weaned calves. SHIPPING: Post Shipment to stocker / feeder (10 – 21 days post arrival). Most common in cattle 6-18mo of age, some older weaned calves too.
what did he say the magic number was in terms of shipping fever-- if it occurs within X time, it wasnt where they are now where they got it, but rather they had it when they got there2 weeks! If thye break illness within 2 weeks of arriving at stocker/feeder, then the stress caused whatever they already had to flare up
what is usually the precipitating factor for shipping fever to occur? explain the pathogenesisSTRESS!!! --> dec immune fxn--> +/- viral infection--> weakened defenses--> bacterial infxn
Enzootic pneumonia vs shipping fever: which is most common in holstein calves?Enzootic pneumonia (makes sense-- very young and stressed and taken from mom at young age bc dairy industry)
enzootic pneumonia vs shipping fever- which is the most common cause of morbidity and mortality in feeder cattle?Shipping! They just got SHIPPED to the feedlot!
BRDC is a multifactorial dz. what are the 3 major factors?STRESSORS, Viruses, and Bacteria
what is the most major stressor which is associated with BRDC?weaning is the biggest stressor. (and the more they bawl/cry the less they will eat)
what are the viral agents which play a role in BRDC? (what are the top 4 concerning ones)PI3, IBR, BVDV, BRSV, adenovirus, rhinovirus, herpesvirus IV, enterovirus, MCF, Reovirus.
what are the bacterial agents which play a role in BRDC? When do they usually cause problems?pasteurella, histophilus, mannheimia (usually in environment and don't cause problems- until there is already a problem in the lungs)
how can you check if there is no airflow in the barn?cobwebs on the ceiling
when (seasonally) is air quality more of an issue, and why?Winter- dec circulation and inc humidity (all stuck inside like that)
what noxious gas are you particularly worried about with poor air circuation/housing?ammonia
what quality of air carries high #s of pathogens?warm, humid air
explain how the barn should be constructed in order to properly ventilate-- and what happens if it is not designed like that.When it doesn't have good ventilation: ..... But when it does: clean (cool) air enters building near the beginning of the ceiling. Cool air sinks so it circulates with the hot/moist air near where the cows are living. Hot air rises so it should escape through a vent in the top of the roof (ridge vent), and it takes the moisture with it (less condensation)
Comfort zone for animals depends on what 3 factors?Age, mass, surface area
Normal ambient temp ranges for calves (<1mo)? Mature cattle? Feeders?CALVES: 59-77*. MATURE: 41-68*. FEEDERS: 14-68
rule of thumb for how much water they need?1 gallon per 100lbs body weight
how much milk does a calf need per day?12-13% body weight in milk a day (gallon of milk is about 8lbs)

Specific agents: Intro and VIRUSES: BVDV, Infectious Bovine Rhinotracheitis (IBR), Bovine Respiratory Syncytial Virus (BRSV), Parainfluenza 3 Virus (PI3)

Question Answer
Abortions?BVDV, IBR
most common VIRUS isolated from CALVES with BRD is?BVDV
Most common clinical signs of BRDC?Nasal Discharge (Crusty Nose), fever, anorexia, depression, ocular discharge, coughing, dyspnea/tachypnea, depression (droopy ears/head), noisy respiration (crackles, wheezes, friction rubs, dec or lack of sounds)
explain the pathogenesis of BRDC- starting with how stress weakens the immune system, and ending with dec productionMCA= mucociliary apparatus Then in words: BRDC agents weaken the host immune system by depressing local cellular immunity as well as humoral immunity. Agents cause damage to the muco-ciliary apparatus (MCA) that helps to remove mucus & debris from the upper airway. Plural adhesions may form due to fibrin deposition, leading to long term lung damage (pleuritis is painful and performance is lost and will not be caught up). Pathogens also cause inflammation & exudation into small airways & alveoli creating a barrier to gas exchange ( Severe cases lead to airway obstruction & atelectasis.)
what are the 4 main viral agents that cause BRD, and which affect upper versus lower respt tract?IBR (infectious bovine rhinotracheitis) is the only URT virus. The other three viruses are LRT: BVDV, Bovine Respiratory Syncytial Virus (BRSV), Parainfluenza 3 Virus (PI3)
what are the 6 bacterial agents which play a role in BRD, and which are URT vs LRT? Fusobacterium necrophorum Is the ONLY URT bacteria. The rest are LRT: Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Mycoplasma bovis, Trueperella pyogenes (Arcanobacterium pyogenes)
what systems does BVDV affect?Mult systems! resp, digestive, repro
what are the 2 strains of BVDV? what are the 2 genotypes?cytopathic and non-cytopathic strains, there is genotype I and II
what is the source of most acute infections of BVDV? how common is this prob?PIs (persistently infected) are the main source- 0.1-0.3% of feedlot cattle are PIs
acute infection of BVDV from a PI can induce acute infections in immuno___ animalscompetent! (vx'ed) (aka if you have an acutely infected animal it can spew out enough virus to affect another immunocompetant/vaccinated animal)
where is BVDV shed from?body secretions and excrements
how does BVV affect the immune system ,what are some results of this? Virus affects lymphocytes, neutrophils, and monocytes-- This causes immunosuppression, leading to 2* infections: Causes leukopenia & lymphoid depletion the spleen, lymph nodes, thymus, and peyer's patches.
how contageous is BVDV? Virus is Easily Transmitted to susceptible animals (70-100% transmission to non-vaccinated feeders.)
Infectious Bovine Rhinotracheitis (IBR) is caused by what?BOVINE HERPES VIRUS 1 (I B(e) (u)R #1 bb)
along with resp dz, IBR also causes what other problems?Conjunctivitis, Abortions, Genital Tract Infections, & CNS Disease. ( Inapparent disease can manifest itself as abortions.)
does BHV-1 cause abortion?Yes! It's the IBR virus, which is resp-- and the resp causes abortion but ofc not the genital one bc that would be too easy to remember
when is the most common time for a IBR outbreak? Often occurs following new additions to the herd.
how severe (morbidity/mortality) is IBR?Respiratory Disease can range from inapparent to severe. Morbidity can reach 100% with a case fatality rate of 10%
what is IBR aka (commonly)?Also know as Red Nose due to the rhinitis that accompanies the disease. (hyperemia of the muzzle, Pustules, crusts, & diphtheritic plaques are often noted.)
when does shedding peak for IBR, how rapidly does it spread?Shedding peaks 3 – 6 days post infection. Virus spreads rapidly due to the low infectious dose (10 3 – 10 4virus particles)
Severity of IBR depends on what?Severity of the disease is dependent upon concurrent or secondary infections present.
what would you say this problem is? which dz is this common in? <img src=""height="200">This is a diphtheric membrane, which happens with a BHV-1 (IBR) infection
Bovine Respiratory Syncytial Virus (BRSV)--> is this more common in young or older animals?young
what problems does Bovine Respiratory Syncytial Virus (BRSV) cause in the lungs? Severe interstitial pneumonia with subplerual and interstitial edema and pulmonary emphysema.
If you saw these lungs, which dz might you suspecT? think BRSV because it causes pneumonia, edema and emphysema-- which can lead to these rib imprints
where is BRSV shed from?spread via resp secretions.
which has only resp signs? (BVDV, IBR, BRSV, PI3)?BRSV and PI3 only has resp signs. BVDV affects mult systems and IBR can also cause aboriton.
what are CSs for BRCV like?Clinical signs are limited to the respiratory tract: Fever, Coughing, Nasal and Ocular Discharge. Severe infection can lead to respiratory distress, open mouth breathing, and sub Q emphysema (withers pinch- you will feel creptius)
how does BRSV lead to SQ emphysema?with enough distress the cupula can rupture--> air goes SQ
Parainfluenza 3 Virus (PI3): which body systems does this affect?Limited to the respiratory tract: Infects epithelial cells from the trachea to the alveoli.
which virus is considered a "primary invader"PI3
what problems in the lungs does PI3 cause, and how does it do this? PI3 causes severe bronchopneumonia via compromise of MCA (mucociliary apparatus)
CSs of PI3 infxn?Fever, Coughing, Nasal and Ocular discharge.
what are two "other" viruses which can be associated with bovine resp dz, is there anything else theyre assocaited with?(1) Bovine Adenovirus: can cause resp or GI dz. Secreted in respiratory secretion and feces- can be found in healthy or sick calves. Respiratory challenges have yielded no lesions. (2) Bovine Coronavirus: Most commonly associated with diarrhea in neonatal calves.. Isolated in nasal and fecal swabs form cattle with BRD. Experimental challenges have been inconclusive.