Disease Testing for Goats: CAE, CL, Johne's & More
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. |
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.
Keep test status where buyers can see it
Herd Manager stores each goat's CAE/CL/Johne's results and dates and flags retests, so your herd's health resume is always current.
Track testing free →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.
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
Frequently Asked Questions
What diseases should I test my goats for?
The big three are CAE, CL, and Johne's, all chronic and often symptomless for years. Depending on your situation you may also test for Q-fever, brucellosis (sometimes required for interstate movement), and use BioPRYN blood testing to confirm pregnancy.
How often should I test my goat herd for disease?
Test your entire herd once a year, ideally in late fall or winter, and test every new animal before introduction. Ask herd-visit pricing from your vet to lower per-animal cost, and in many states owners may draw blood themselves for approved labs.
How is CAE, CL, and Johne's testing done?
Mostly by a blood test (ELISA) that detects antibodies, sent to a lab like WADDL or TVMDL; CL abscesses can also be cultured and Johne's checked by fecal PCR. Costs run roughly $3 to $10 per animal for the blood panels.
What should I do if a goat tests positive?
Don't panic — confirm with a retest first. If confirmed, work with your vet on a plan, which may range from culling the animal to a test-and-separate program. Ignoring a positive is the worst option, since these diseases spread and don't resolve on their own.
Why does disease testing matter when buying or selling goats?
Untested purchases are the most common way CAE, CL, and Johne's enter a clean herd, so buyers increasingly expect documented negative results. Annual testing with shared results is one of the strongest marketing tools a seller has.
Every goat's test status at a glance
Herd Manager stores disease-test results and dates on each goat's profile, shows your whole herd's status at a glance, flags when annual retests are due, and lets you share documentation with buyers.
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