Sheep johnes

What is the pathogen responsible for Ovine Johne's disease?

Mycobacterium avium subsp. Paratuberculosis.

How are sheep infected with Ovine Johne's disease?

Through faeco-oral transmission, via milk or colostrum.

What distinguishes subclinical carriers of Ovine Johne's disease?

They shed bacteria that can infect youngstock.

What type of herds are more likely to experience Ovine Johne's disease?

An individual animal problem as opposed to a herd problem.

What clinical signs are associated with Ovine Johne's disease?

Weight loss is a common clinical sign.

Is scour likely to be a symptom of Johne's disease?

Unlikely; if scour is present, it may not be Johne's.

What is the typical culling rate indicator in Ovine Johne's disease investigation?

High culling rates can indicate the presence of the disease.

What are the two primary exam areas when investigating suspected Johne's disease in sheep?

Body Condition Score (BCS) and signs of submandibular or brisket oedema.

What blood results differentiate Johne's disease from fluke infections?

Low albumin levels; Johne's typically presents with low albumin without the increase in globulin seen in fluke.

What type of examination is performed during a post-mortem for suspected Johne's disease?

Examination for granulated or inflamed intestinal lining.

When is serology or ELISA effective in diagnosing Johne's disease?

It detects antibodies which will be low until clinical disease appears, typically around 2-3 years.

What is the recommended action when dealing with infected sheep for treatment of Ovine Johne's disease?

Cull the affected sheep; there is no treatment.

Which management practice helps control Ovine Johne's disease by removing high-risk animals from the flock?

Lambing thin, old, or high-risk ewes away from the rest of the flock.

What hygiene practices help in controlling Ovine Johne's disease transmission?

Maintaining good hygiene and clean bedding during lambing.

What does vaccination do in the context of Ovine Johne's disease?

It reduces shedding and clinical signs but does not prevent infection.

Why is vaccination not widely used for Ovine Johne's disease?

It interferes with TB test results.

What is a major issue in diagnosing Ovine Johne's disease?

The low sensitivity of diagnostic tests.

What complicates the detection of sub-clinical Ovine Johne's disease cases?

The difficulty in identifying sub-clinical animals.

What types of agricultural practices pose a risk for spreading Ovine Johne's disease?

Co-grazing and spreading of slurry between sheep and cattle.

What is the main investigatory procedure for suspected Ovine Johne's disease?

Clinical examination followed by blood sampling and post-mortem examination.

What is the indicator of Ovine Johne's disease in youngstock?

Infection from both subclinical carriers and clinical shedders.