Disease Testing

Why is disease testing important? Isn't a healthy appearance enough?

When bringing new animals to the farm (even before you purchase), evaluating physical health is a must. I like to run through a Five Point Check before deciding to bring a goat home (follow the link to learn more):

Eye - FAMACHA
Back - Body Condition Score (BCS)
Rear - Fecal Soiling
Jaw - Bottle Jaw
Nose - Nasal Discharge

I like to include two more criteria:

6. Hooves - Foot Rot/Scald

7. Mouth - Tooth Alignment, Age

If everything checks out, homeward bound we go! All goats entering the farm are placed in a 30 day quarantine so they can be evaluated for signs of respiratory disease and stress-induced bacterial and parasitic infections. End of story, right?

Not quite.

A physical exam can tell you many things, but it only scrapes the surface; to be confident bringing new animals into the herd, you need to dig a little deeper.

While there are a couple different diseases you can test for, most producers pursue the 'Big Three': CAE, Johnes, and CL. The presence of any of these diseases in your herd can mean hindered production, increased management, fewer market avenues, and reduced animal welfare. Infected animals are not always visibly apparent, especially since symptoms may take months or years to arise. By purchasing stock from disease tested herds and testing your own herd, the chance of introducing contagions or unwittingly allowing them to remain undetected is greatly reduced.

When beginning to test your herd, it is recommended to complete two whole herd tests 6 months apart followed by annual testing. However, it is not always economical (particularly with large herds). If risk is relatively low (such as purchasing from disease tested herds with proof of testing, maintaining a closed herd, or having already conducted full herd testing), a producer may choose to break their herd into testing groups and only test a percentage of the herd each year. For example, a farm with 200 goats may choose to test 25% each year in order to get a reasonable representation of the entire population. Find what works for your herd!

At Browns Branch Acres, we test all incoming stock and perform yearly whole herd testing.

What is Caprine Arthritis Encephalitis (CAE)?

CAE is a contagious lentivirus (characterized by their long incubation periods and ability to integrate into a host's genome) similar to that which causes ovine progressive pneumonia (OPP) in sheep.

Modes of Transmission: Colostrum and milk of CAE+ does is the primary and most common means of infection. Blood is considered the secondary mode of transmission, but horizontal transmission between CAE- and CAE+ does is rare except during kidding and lactation. Any bodily fluids or excretions which contain white blood cells are potential, although uncommon, sources of disease.

Symptoms: CAE presents in five forms (arthritis, mastitis, chronic wasting, encephalitis, and in some cases pneumonia). Goats can be asymptomatic, but they are still capable of transmitting disease.

Adults: Arthritis and mastitis are the most common symptomologies.

Swollen joints
Walking on knees
Stiffness
Hard, swollen udder
Low milk
Weight loss
Chronic cough
Difficulty breathing

Kids: Encephalitis is the predominant form and typically affects kids under 6 months of age.

Uncoordinated movement
Paralysis
Blindness
Seizures
Stiffness
Twitching or highly reactive muscles
Death

Treatment: Currently, there are no known treatments for CAE, but a herdsman can provide pain management to symptomatic animals. Encephalitic CAE is almost always fatal.

Read more on prevention and CAE management:

https://animalhealthaustralia.com.au/wp-content/uploads/2015/09/CAE-Voluntary-Guidelines-Document_FA_web-002-002.pdf

https://www.canr.msu.edu/news/caprine-arthritic-encephalitis-virus-in-goats

What is Johne's?

Johne's is a fatal gastrointestinal disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). While initial infection typically occurs at a young age, symptoms often take years to arise.

Modes of Transmission: Contact with feces of infected animals through the consumption of contaminated milk, grass, feed, soil, bedding, or water. Newborn kids are especially prone to picking up MAP from the environment or from nursing contaminated teats shortly after birth. Does in the late stages of infection may shed MAP in their milk or transmit infection to kids in-utero.

Symptoms: Rapid weight loss despite good nutrition and normal feed intake is the most common symptom. A previously healthy adult animal may suddenly and rapidly decline despite no evidence of visible disease, parasitism, or malnutrition. Diarrhea is a less common symptom in goats, but is readily present in bovines.

Treatment: No treatment currently exists for Johne's. Due to its highly contagious, progressive, and inevitably fatal nature, euthanasia is recommended.

Prevention: Only purchase from farms with whole herd negative Johne's testing. Quarantine all incoming animals and perform testing before releasing to the primary herd (even if coming from a disease tested farm). If you suspect Johne's, immediately quarantine afflicted animals. A fecal PCR or culture are the most accurate methods for diagnosing Johne's infection.

For more information on Johne's:

https://adga.org/johnes-disease/

https://johnes.org/goats/faqs/

What is Caeceous Lymphadenitis (CL or CLA) and why don't we test for it?

Caeceous lymphadenitis is a chronic, infectious disease caused by the Corynebacterium pseudotuberculosis bacterium. CL can be found in and transmitted between horses, goats, sheep, bovines, swine, rabbits, and humans (zoonotic) as well as many other species. While CL can be managed, its presence in a herd can lead to marketability issues, condemned carcasses, and lower valued hide and fiber. Clinical disease usually arises in 1-3 months after initial infection. The bacterium has been shown to survive in soil for 8 months and in bedding for 2 months; moisture, organic matter, and shade have been shown to prolong the bacterium's survival.

Modes of Transmission: Ingestion, inhalation, or mucosal contact with C. pseudotuberculosis infected pus. Shearing tools, stanchions, chutes, brushes, feeders, soil, and other equipment can also act as fomites (contaminated objects which can produce disease). Insects (primarily flies) can act as vectors capable of carrying bacterium to other farms.

Symptoms: Enlarged lymph nodes filled with thick, white pus. CL abscesses often arise just under the jaw or over the shoulder, but they can appear at any lymph region on the body (see diagrams below for lymph areas). Goats tend to develop the external form of the disease while sheep commonly develop its internal form. If ruptured, abscesses that form on the lungs or in the mammary can enable transmission through coughing or milk. CL presenting internally can induce ill thrift, chronic weight loss, and death.

Treatment: CL abscesses can be lanced, drained, and flushed to speed up healing. However, there is no cure. Infected animals will remain positive for the disease their entire life; abscesses can reoccur after being drained. Some animals may never have visible reoccurrence of disease and can live a long, otherwise healthy life. To prevent its spread, strict biosecurity protocols must be used. Animals with active abscessation should be quarantined away from the primary herd in an easily sanitized location. Always wear gloves and wash hands thoroughly when handling an actively draining CL abscess.

Prevention: Do not purchase animals with lumps or abscesses present in lymph node regions. Consider purchasing from CL negative tested herds. Some herds may consider administering a CL vaccine, especially in regions where deer populations or infection risk is high. Vaccination will produce an immune response in the animal therefore leading to a positive serum result; vaccination does NOT induce disease. It is assumed that a vaccinated animal will remain positive for CL antibodies throughout its life. If purchasing from a vaccinated herd, inquire into the reason behind the decision to vaccinate.

Previous herd exposure to a CL positive animal with a draining abscess?
Biosecurity precaution (never actually had a CL positive animal)?

Not all producers will be truthful with their herd's disease exposure, so asking for advice and references from other producers can aid you in selecting healthy stock.

At this time, we have not tested our herd for CL. The disease is highly visible due to predominantly external abscess formation; therefore, we do not see an innate need to test for disease. We do plan to test for CL in summer 2021, particularly four vaccinated does we acquired, in order to evaluate vaccine antibody longevity.

Learn more about CL vaccines:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923401/

Have you ever had a goat test positive or show symptoms of any of these 'Big Three' diseases?

The answer is yes. We have personally encountered both CAE and CL, but NOT Johnes.

Our run-in with CL actually occurred when we first acquired Kikos back in 2018. In the original group of does we purchased at the Spotlight Kiko Sale in Crossville, TN, we unknowingly selected a large white doe whom was already presenting the disease. Having not handled the doe thoroughly before bidding (mistake #1) and assuming state vet clearance and being checked by on-site veterinarians meant animals were disease free (mistake #2), we snatched up the doe and continued blissfully unaware until the Wilsons at Circle W Ranch were kind enough to point out the abnormal lump situated on the doe's shoulder. She was immediately quarantined separate of the other does and later euthanized by the Delaware state veterinarian; bacterial culture confirmed that the lump was an active CL infection.

Since this event, none of our goats have shown visible signs of CL. While our veterinarian did recommend starting a CL vaccination program for our herd due to the exposure risk, we instead implemented a whole farm quarantine and did not move any goats off-farm until the possible incubation period had passed.

We encountered CAE for the first time after disease testing our whole herd in August 2020. A lamancha yearling that I had acquired as a bottle baby from a Pennsylvania dairy farm, affectionately named Ambrosia, popped a low positive for CAE in two consecutive tests. She wasn't symptomatic and had never freshened, so I eventually rehomed her to a small farm that took in and managed CAE+ goats.

Where can I test my herd?

As you can tell from our test reports, we currently conduct all of our testing through Universal Biomedical Research Laboratory (UBRL). This lab offers user friendly guidelines for collecting, storing, and shipping blood samples (all while being economical!).

*We may be switching to Delta Livestock Diagnostics to account for herd growth*

While UBRL is our current lab, we do recommend Washington Animal Disease Diagnostic Laboratory (WADDL) and Delta Livestock Diagnostics.

(Click the names to reach their websites!)

Supplies Needed: