27: Abortion 1

How likely are we to diagnose the cause of abortion

Not very :(

Since diagnosing abortion is hard, what is our goal when working with a client to figure out why their animal aborted

Rule out the “big baddies” for your clients

Why is fetal stomach fluid a great sample to submit for abortion testing

When a fetus is under stress (ex: getting aborted) they swallow more, meaning there is amnionic fluid in their stomach at the time of the abortion and we can see what the placental/amnionic environment is like

What is a “select agent”

The worst infectious and toxic causes of disease

Who maintains a list of “select agents”

The USDA

Most common route of uterine inflammation and infection in horses

Ascending infection from the cervix

Causes of bacterial abortion that are zoonotic

• Brucella

• Campylobacter, Chlamydia, Coxiella burnetii

• Leptospira

• Listeria

Causes of bacterial abortion that are reportable

• Brucella

• Coxiella burnetii

• Contagious equine metritis

Why do all small ruminant abortions submitted for pathology go under the hood

Coxiella burnetii (Query fever)

Which specie gets abortion from Actinomycetes

Horses

In horses that abort from Actinomycetes, where did the infection come from

Hematogenous spread

Disease process caused by Actinomycetes in horses

Nocardioform placentitis

Lesions on an equine placenta associated with nocardioform placentitis

Inflammation and infection NOT at the cervical star

If you see lesions on an equine placenta that are not at the cervical star, what are your two differentials

Actinomycetes or Lepto- they are the only ones that cause systemic abortion instead of an ascending infection!

Four outcomes associated with Actinomycetes

• Abortion

• Stillbirth

• Delivery of premature foal

• Delivery of normal, healthy foal

What determines the outcome for mares with Actinomycetes

We don’t know :)

What type of bacteria is Brucella

G- facultative intracellular coccobacillus

Smooth v rough strains of Brucella

Smooth strains have more S-LPS and are more virulent while rough strains have no S-LPS

Common Brucella spp. that are smooth strains

• S: B. suis

• A: B. abortus

• M: B. melitensis

When we do agglutination tests for Brucella how do we differentiate between smooth and rough strains

Smooth strains will cross-react with other smooth strains and rough strains will cross-react with other rough strains

How is all Brucella transmitted

Direct contact with fetal or reproductive tissue/fluid

Tissues that Brucella has a tropism for

Mammae and repro tissues

Pathogenesis of brucellosis

Direct contact → picked up by macrophages → bacteremia → sequesters in certain tissues → inhibits phagolysosome fusion

Diagnosis for brucellosis

• Agglutination tests

• Complement fixation

• ELISA

• Culture

Common antemortem agglutination test for brucellosis

Milk ring test

How does a positive milk ring test for brucellosis work

Added antibodies will bind to Brucella antibodies that are in the cream, which then floats to the top and forms a colored ring

While all species of Brucella can cause abortion in females, which are more likely to cause disease in males

Brucella canis, ovis, and suis (they all have the animal name!)

Brucella abortus is host-adapted to which specie

Cattle

Reservoirs for Brucella abortus

Bison and elk in the Greater Yellowstone Area

Gross lesions associated with Brucella abortus in cows

Necrotizing placentitis

What other disease in cows is brucellosis identical to

Coxiella burnetii infection

Treatment for Brucella abortus

Cull

Prevention for Brucella abortus

Vaccinate!

Specific vaccine for Brucella abortus

Brucella R51 vaccine

What type of vaccine is the Brucella R51 vaccine

Live attenuated vaccine made from the rough strain

Why is the Brucella R51 vaccine made from a rough strain if Brucella abortus is a smooth strain

The rough strain is less zoonotic and it means the vaccine doesn’t interfere with agglutination testing

Who can give the Brucella R51 vaccine

Level 2 accredited veterinarians

Who can get the Brucella R51 vaccine

4-12 month old heifers

Specie of Brucella that is technically a foreign animal disease

Brucella melitensis

Brucella melitensis is host adapted to which specie

Goats and sheep

CS of Brucella melitensis

Orchitis > abortion, arthritis

Lesions caused by Brucella melitensis

Necrotizing placentitis

If you see necrotizing placentitis in a small ruminant, what are you going to thing of way before brucellosis

Coxiella burnetii

Brucella specie that is specifically host-adapted to sheep

Brucella ovis

CS associated with Brucella ovis

Epididymitis and orchitis in males >> abortions in females

Inconvenient wild reservoirs for Brucella suis

Feral hogs (and caribou)

CS associated with Brucella suis

Severe epididymitis and orchitis, occasionally discospondylitis

CS associated with Brucella canis

• Orchitis and infertility

• Discospondylitis

• Occasionally skin or ocular disease

Brucella species that potentially can infect horses

Brucella abortus or suis

Odd disease presentation of brucellosis in horses

Sequesters in bursae → chronic, suppurative bursitis (AKA poll evil and fistulous withers)