Chlamydia in sheep: Causes and treatment

AbbyMac By AbbyMac, 13th Jul 2010 | Follow this author | RSS Feed
Posted in Wikinut>Guides>Pets>Farm Animals

Chlamydia in sheep is caused by a bacterial infection with the potential to devastate the whole flock.

The effect

The strain of bacteria involved in ovine chlamydia will determine the effect on the health of the sheep, ranging from an asymptomatic carrier who is otherwise healthy to wide-spread abortion, impacting an entire season of lambing.

Chlamydophila pecorum

C. pecorum

The bacteria Chlamydophila pecorum is implicated in an enteric form (pertaining to the intestines) of chlamydia and can cause chlamydial arthritis (or polyarthritis) leading to conjunctivitis. The animal presents with stiffness, fever and lameness. Often the host animal shedding the bacteria is asymptomatic, having already developed an immunity.

Chlamydophila psittaci

C. psittiaci

Another bacteria, Chlamydophila psittaci, can lead to pneumonia and abortion depending on the specific strain of C. psittaci present. Chlamydial bronchopneumonia is contracted through the inhalation of the bacteria shed from infected animals. The clinical signs are fever, labored breathing, anorexia, lethargy and, in lambs, possibly death.

Chlamydophila abortus

C. abortus

The most devastating of these bacterial infections to the sheep farmer is chlamydial abortion, or Enzootic Abortion in Ewes (EAE) caused by C. abortus, also known as C. psittaci serotype 1. Enzootic refers to the bacteria being endemic to a specific locale. EAE can spread through a flock causing abortions and stillbirths, weak lambs, or normal lambs that do not grow well. The ewe may have been infected the previous season, had a normal delivery, then aborted the following year. This form of chlamydia most often occurs when a new animal has recently been introduced in the flock.

Once chlamydial abortion has been diagnosed the rest of the flock can be successfully treated with tetracycline. The infected ewe will build up an immunity to it for subsequent lambings though her female lambs will be carriers and may also abort their first year of lambing. Treatment for the whole flock is important as the infected ewe can pass the bacteria on to the ram who then can spread it to the rest of the ewes through breeding.

In all cases the onset of disease seems to be more marked in crowded conditions or stressful situations where possibility of inhalation or ingestion of the bacteria is increased. In all these forms of chlamydia, tetracycline is the antibiotic of choice.

The chlamydia bacteria is also zoonotic. It can be spread to other species including goats, cattle and occasionally humans. A person can catch the pneumonial form, though most likely from a pet bird. Human cases of C. abortus always involve pregnant women, most of whom will miscarry, so caution should always be taken for pregnant women working around sheep.


Merck Veterinary Manual

United Suffolk Sheep Association

Purdue University Sheep Extension p/articles/sicksheep.html


C Abortus, C Pecorum, C Psittaci, Chlamydia, Sheep

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author avatar AbbyMac
I am a mother of two teenage girls, living on a farm where we raise award-winning Corriedale Sheep. I have homeschooled for 11 years and currently own a homeschool curriculum store. I enjoy writing about homeschooling, animals and mysteries of the ...(more)

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