CS: endemic disease and underperformance in cattle 1 Flashcards
How big a problem is IBR?
- becoming less of a common problem
- outbreaks can still be nasty
What parasite is very important in beef management?
ostertagia
How do you assess for presence of an endemic dz?
- Bulk /age group/ individual milk Abs, Ags
- Faecal Ag (Johne’s)
- TB IFN test and skin test
- Sentinel group
- FEC – young/old (wax and wane, positive may not always be a pathogen)
- Serology - blood antibody titres /antigen titre (some practices offer this for free)
- DIVA vaccines
- CMT
- Mobility scoring
- Incidence of ketosis, milk fever etc (farm record dependent)
CS - BVD
- infertility
- abortions/stillbirths/mummification –> increased return to oestrous
- birth defects (nervous system, eyes)
- weak and sickly and premature
- ill thrift/ stunted growth rate
- poor condition
- high levels of concurrent /secondary infections (pneumonia, scours)
- reduced milk yield/productivity/ live weight gain
- potentially mucosal disease (6-18m)
Tests to investigate presence of BVD
Antibody ELISA (blood, milk) - acute BVD infections
- paired blood samples 2-4 weeks apart to demonstrate rising Ab levels to virus
- not to identify PI calves but exposure i.e. virus (been) circulating in a group. Testing for virus will ID PI calves (2 positive samples taken 3-4 weeks apart will confirm PI although one test usually enough)
- bulk milk BVD-antibody test to see if there has been contact in the preceding years (or active infection if high levels)
- blood test antibody test in young stock to see if recent contact with BVDV in preceding months i.e. active BVD on farm, likely presence of PIs
How do identify BDV PI calves
need to detect VIRUS/RNA:
- bulk milk BVDV PCR - are there PIs in the milking herd?
- young stock blood samples for antigen ELISA (or virus isolation, or immunoperoxidase - can also use tissue e.g. ear notch). 2 samples at least 3wks apart distinguishes from acute infection
Considerations for a closed herd free from BVD
Closed herd free from disease: infrequent testing unless outbreak is suspected based on clinical signs. The testing should target young stock. Test 10 % as sentinels of disease if negative then likely disease not present.
Risk from contaminated semen can be minimised by either using AI stud semen (tested) or testing for BVD virus prior to purchasing a bull
How to eradicate BVD from an infected herd
- Eradicate reservoir of virus in PI calves = eradicate source of infection: test for virus (as above) -> identify and cull PI calves
- Vaccinate all breeding females to prevent birth of new PI animals - Killed vaccine hence 1o course of 2 injections: must be WELL BEFORE 1ST SERVICE (e.g. yearlings) - Thereafter boost before each service to ensure maximal immunity at time of greatest potential risk (early-mid pregnancy) - Where active infection, may need to vaccinate other stages, and possibly calves to protect from acute infection (or potentially vaccinate few weeks before calving dam to boost colostral antibodies)
- Continue blood monitoring of all calves born into herd for 12m after last PI identified and culled
- Purchase animals from accredited herds OR quarantine for 1m then blood test for antibody, then virus if seronegative (earlier if no pre-purchase screen at farm of origin). Cows bought in-calf quarantined until parturition, screen calf asap (see if PI) (or eradicate PIs then maintain as closed herd?)
CS - IBR
- range of dz, life-long infection (sensory ganglia), shedding of virus at any point
• Rhinotracheitis (**, commonest CS)
• Can also cause reproductive, nervous and neonatal disease
• High morbidity rates
• Often amongst housed cattle – recently purchased
• Severity of disease depends on 2* infection
• Nasal discharge – serous develops to purulent
• Fever – up to 42*C
• Coughing
• Poor fertility
• Conjunctivitis
• Decreased milk yield
• Depression
• Loss appetite & weight loss
• Mucosal lesions
• Hyperaemia
• Abortion
Pathogenesis - IBR
- Virus excreted from mucosal surfaces
- Viraemia is difficult to detect
- Any animal with detectable antibody must be infected: Life-long latent infection; Possible source of virus
Diagnosis - IBR
- Serology – Ab 2-6 weeks post-infection, highest during early CS, virus neutralisation (collect 1 sample then 2nd 4 weeks later). ELISA. DIVA vaccines available
- Virus isolation: nasal/vaginal swab, sperm sample, tissue, sample (dead/aborted), must be collected during acute disease (as –> latent with chronic disease)
- BMT - serology, PCR
What is the biggest biosecurity risk for IBR - free herds?
buying in infected animals
What are the vaccines for IBR?
- MLV, inactivated, killed
* 4-6 months old
Outline transmission of BVD
- oronasal • Contaminated semen • Embryo transfer • Humans • Contaminated materials • Airborne transmission
Neospora caninum - CS
often no CS except early embryonic death (infected
