Quick Guide to Cattle Diseases
IBR is an acute viral disease. In young animals it mainly affects the upper respiratory tract and can lead to a fatal pneumonia. In mature animals it can also cause abortions and reduced fertility. Once infected an animal remains infected (becomes a carrier) for life and may release infected virus throughout its life when stressed. It is spread via airborne secretions and bulls’ semen. For pedigree breeders IBR is important in that animals and herds that have had contact with IBR are barred from export to certain countries.
BVD is a complex of diseases of viral origin. Effects of the disease may be reduced fertility, abortion, foetal abnormalities, enteritis and mucosal disease. It is spread by PIs (Persistently Infected calves) nasal secretions and semen from transiently infected bulls, contaminated needles and equipment. Control is by bio security, removing persistently infected (PI) animals and vaccination.
Leptospirosis disease in cattle is caused by two species of Leptospiria characterised in dairy cattle by milk drop, poor fertility and abortions and in beef cattle by poor fertility and abortions in the second half of pregnancy. Infection is via infected urine either from the cow or urine contaminated water or pasture. Risk factors include using natural service, sharing pastures with sheep, allowing access to open watercourses and buying in stock with unknown disease status. Infected animals may be carriers for life. It can affect human beings causing flu like symptoms, and in rare cases fatalities. Effective control in an infected herd may be achieved through a vaccination programme.
Johnes Disease (paratuberculosis) also known as MAP (the infectious organism) is a chronic infectious bacterial enteritis that results in persistent diarrhoea, progressive wasting and eventual death. It has an incubation period of 2-6 years. Animals are usually infected when young. The calf may be infected while in the womb, by drinking infected colostrum and milk, or consuming food and water contaminated by Johnes infected faeces. The organism may last for a year in slurry or on pastures. In the individual animal diagnosis by laboratory means is unreliable until the disease symptoms are well established and hence a whole herd testing procedure is adopted.