Disease Testing for Goats: CAE, CL, Johne's & More

Last updated: March 2026 · 5 min read

Disease testing is the foundation of a healthy, marketable goat herd. The major infectious diseases — CAE, CL, and Johne's — can silently spread through a herd for years before symptoms appear. By then, most of the herd may be infected. Regular testing identifies infected animals, protects your clean animals, and gives buyers confidence in your herd's health status. If you sell goats, testing is not optional — it is expected.

The Big Three

CAE (Caprine Arthritis Encephalitis)

CAE is a viral disease caused by a lentivirus (similar to HIV in structure, but not transmissible to humans). It causes chronic, progressive arthritis in adult goats and encephalitis (brain inflammation) in kids. There is no cure and no vaccine.

Aspect	Details
Transmission	Primarily through infected milk and colostrum (dam to kid). Also through direct contact with bodily fluids over prolonged close contact. Blood-to-blood transmission (shared needles, dehorning equipment).
Symptoms	Swollen knees (big knee), chronic lameness, gradual wasting, hard udder (chronic mastitis form), poor milk production. Many infected goats show no symptoms for years.
Test	Blood test (ELISA). Detects antibodies to the virus. Blood drawn by vet or owner (if state allows) and sent to an approved lab.
Cost	$3 to $8 per animal per test
Frequency	Test annually. Test all new animals before introduction to your herd.
False negatives	Possible in recently infected animals (antibodies take 2 to 8 weeks to develop) and in kids under 6 months (may have maternal antibodies). Retest suspicious animals 60 days later.

CAE prevalence: Estimated at 30 to 80% of US dairy goat herds have at least one positive animal. Many goats are asymptomatic carriers. Do not assume your herd is negative without testing. The most common source of CAE introduction is purchasing untested animals.

CL (Caseous Lymphadenitis)

CL is a chronic bacterial infection caused by Corynebacterium pseudotuberculosis that causes abscesses in lymph nodes. External abscesses are visible as lumps under the skin, typically around the head, neck, and shoulders. Internal abscesses affect the lungs, liver, and other organs and are not visible externally.

Aspect	Details
Transmission	When an abscess ruptures, the pus is extremely contagious and contaminates the environment (soil, fences, feeders). Other goats are infected through skin wounds, abrasions, or mucous membranes. The bacteria can survive in soil for months to years.
Symptoms	Firm lumps under the skin near lymph nodes (jaw, shoulder, flank, udder area). Internal form: chronic weight loss, poor condition, respiratory issues. Some goats are carriers with no visible abscesses.
Test	Blood test (SHI or ELISA) detects antibodies. Culture of abscess material confirms the organism. Blood tests can have false positives and false negatives.
Cost	$3 to $8 per animal (blood test). Culture: $15 to $30.
Frequency	Test annually. Test all new animals. Retest any animal with suspicious lumps.

Managing a CL-positive goat: If an abscess develops, isolate the goat immediately. The abscess can be lanced and flushed by a vet in an isolated area, with all contaminated material collected and burned or disposed of in sealed bags. The bacteria in CL pus is a zoonotic risk — wear gloves and practice strict hygiene. Many breeders cull CL-positive animals to protect the rest of the herd.

Johne's Disease (Paratuberculosis)

Johne's (pronounced "YO-knees") is caused by Mycobacterium avium subspecies paratuberculosis (MAP). It causes chronic inflammation of the intestines, leading to progressive weight loss and eventually death. There is no cure.

Aspect	Details
Transmission	Fecal-oral route, primarily. Kids are most susceptible. Infected adults shed the bacteria in feces for months to years before showing symptoms. Also transmitted through infected milk and in utero.
Symptoms	Chronic wasting, weight loss despite good appetite, rough coat, decreased production. Diarrhea is less common in goats than in cattle with Johne's. Symptoms typically appear at 2 to 5 years of age.
Test	Blood test (ELISA) for antibodies, or fecal culture/PCR for the organism. Blood tests have lower sensitivity in early infection. Fecal PCR is more sensitive but more expensive.
Cost	Blood ELISA: $5 to $10. Fecal PCR: $20 to $40.
Challenge	Long incubation period (1 to 3+ years). Goats can test negative for years while infected and shedding. This makes Johne's the hardest of the three to eradicate from a herd.

Other Tests to Consider

Q-Fever (Coxiella burnetii)

A bacterial infection that can cause late-term abortion in goats and is zoonotic — it can infect humans, especially during kidding when the organism is shed in birth fluids. Consider testing if you have unexplained late-term abortions or if people on your farm are immunocompromised.

Brucellosis

Federally regulated disease. Most US herds are brucellosis-free, but testing may be required for interstate movement or sale at certain markets. Your state veterinarian can advise on requirements.

Pregnancy testing (BioPRYN)

While not a disease test, BioPRYN is a blood test that detects pregnancy-associated glycoproteins. Blood drawn at 30+ days post-breeding confirms pregnancy with high accuracy. Useful for pen-breeding situations where you are not sure which does settled.

When and How to Test

Annual herd testing

Test your entire herd once per year, ideally in late fall or winter (before breeding season or before kidding)
Many vets offer herd-visit pricing that reduces per-animal costs when testing multiple goats at once
Blood draws can be done by your vet or, in many states, by the owner using proper technique and approved sample submission

Testing new arrivals

Before purchase: Ask for current test results (within the last 12 months). Reputable breeders test annually and share results willingly.
On arrival: Quarantine for 30 days and test immediately. Do not introduce to your herd until results are back and negative.
Retest at 60 days: For CAE especially, a recently infected animal may not have developed detectable antibodies at the first test. A second test at 60 days post-arrival catches these.

Where to send samples: WADDL (Washington Animal Disease Diagnostic Lab) and TVMDL (Texas A&M Veterinary Medical Diagnostic Lab) are two of the most commonly used labs for goat disease panels. Many state veterinary diagnostic labs also offer these tests. Your vet can advise on the best lab for your area and often handles submission for you.

Building a Clean Herd

The goal of disease testing is not just knowing your herd's status — it is building and maintaining a disease-free herd. This requires a systematic approach:

CAE prevention program

Test all animals annually
Remove kids from positive dams immediately at birth (before nursing)
Feed heat-treated colostrum (135 degrees F for 1 hour) and pasteurized milk
Separate positive and negative animals — do not share milking equipment, water buckets, or needles
Use separate needles for each animal during vaccinations and blood draws
Over time, cull positive animals as their productive life ends and retain only negative offspring

CL prevention

Never buy an animal with visible lumps without having them cultured first
Isolate any goat that develops a lump immediately
If an abscess ruptures, clean and disinfect the area thoroughly. Contaminated soil can remain infectious for years.
A CL vaccine exists (Colorado Serum Company) but is controversial — it can cause injection site reactions and interferes with blood testing. Discuss with your vet.

General biosecurity

Quarantine all new arrivals for 30 days minimum with testing
Do not share equipment (hoof trimmers, tattoo equipment, needles) between herds without thorough disinfection
Use fresh needles for each animal
Clean and disinfect kidding areas between does
If you attend shows or take goats off-farm, quarantine them on return
Keep records of every test result, every animal, every year. This documentation is your herd's health resume.

What to do if you get a positive result: Do not panic. A single positive test needs confirmation — request a retest. If confirmed positive, work with your vet to develop a management plan. Depending on the disease, your herd size, and your goals, options range from culling the individual animal to implementing a test-and-separate program. The worst thing you can do is ignore a positive result — it does not go away on its own, and it will spread.

Marketing a Tested Herd

Annual testing with documented negative results is one of the strongest marketing tools you have. When selling goats:

State "Annually tested CAE/CL/Johne's negative" in all listings
Provide test results to buyers (dates, lab, results)
Serious buyers will ask for test results — having them ready shows professionalism
Many buyers will not purchase from untested herds, regardless of price
Testing costs pennies compared to the value it adds to every animal you sell

Track disease test status for every goat

Herd Manager stores disease test results and dates on each goat's profile. See testing status at a glance across your whole herd, track when annual retests are due, and share test documentation with buyers.

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