6 Case Studies on Reproductive Failure in Cattle
Case Study on Reproductive Failure in Cattle
Introduction
Reproductive failure significantly reduces farm productivity. Although infectious causes account for no more than 25% of cases overall, they can lead to outbreaks in immunologically naïve herds. Such outbreaks warrant thorough investigation.
Refer to the chapters on Enterobacteriales (Salmonella), Spirochaetes (Leptospira), and Campylobacter to answer the case study questions.
Case History
A 200-cow dairy farm in the Atherton Tablelands reported six abortions occurring within a few weeks, primarily during the late second to last third trimester of gestation. One foetus was available for post-mortem examination. Additionally, one calf was born alive but deteriorated rapidly and died. A replacement calf on the farm developed illness characterized by jaundice and haemoglobinuria (red urine). Some cows with calves at foot had poorly distended udders, and their calves were underweight.
Common infectious causes of reproductive failure in Australian cattle include:
- Bovine campylobacteriosis
- Leptospira serovars
- Pestivirus infections
- Neosporosis
- Tritrichomonas
- Arboviruses (Akabane, Aino, Palyam – mosquito transmitted)
- Septic abortion (Listeria, Salmonella, Trueperella, moulds)
Important note: Brucella abortus, a significant cause of bovine abortion globally, is not present in Australia.
Case A: Most likely Bacterial Cause
Read through the case history to answer the questions below.
Questions
- Which bacterial disease is most consistent with the case history?
- Justify your suspected diagnosis by explaining how the observed clinical signs relate to the pathogenesis of this disease.
- What samples and diagnostic tests would you collect from the affected animals and the aborted fetus to confirm your suspected diagnosis?
Case B: Leptospirosis Control in Cattle
Leptospira serovars are common causes of reproductive failure in cattle and other animals. They also pose an occupational risk to people working with these animals.
Questions
- What are the main sources and routes of transmission of Leptospira in cattle herds, and how do these influence control strategies?
-
Discuss the role of vaccination in controlling leptospirosis in cattle. What are its limitations and how should it be integrated with other control measures?
Case C: Salmonella as a cause of septic abortion in cattle
The serovars of enteric agent Salmonella infect a wide range of animals and people. Production and other stressors enhance the susceptibility of animals to this bacterial pathogen.
Questions
- Which Salmonella serovars are most commonly implicated in bovine abortion, and what is their significance for public health?
- Explain how Salmonella can lead to abortion in cattle. What is the pathogenesis from initial infection to foetal loss?
- Why is Salmonella-induced abortion often associated with systemic illness in the dam? How does this differ from other causes of abortion?
Case D: Genital campylobacteriosis (Vibriosis) in Cattle
Animals are carriers for this very hard to recognise cause of reproductive losses in cattle and other ruminants. Whilst the questions don’t ask how Campylobacter infections are diagnosed, detecting the agent in carrier animals is a requirement for an effective control programme.
Questions
- a) What clinical signs and herd-level patterns would make you suspect Campylobacter as the cause of reproductive failure?
- b) Describe the differences in herd-level patterns between the different Campylobacter species involved.
-
Outline effective control and prevention strategies for bovine campylobacteriosis. How do these differ from control measures for leptospirosis or Salmonella abortion?