Caprine Arthritis and Encephalitis (CAE) in Goats: Signs, Testing, and Care

Caprine arthritis and encephalitis, usually called CAE, is a contagious viral disease of goats caused by a lentivirus, a type of retrovirus in the small ruminant lentivirus group. Once a goat is infected, the infection is generally lifelong. Many goats stay outwardly normal, but others develop chronic inflammation that affects joints, the nervous system, udder, or lungs.

The disease can look different depending on the goat's age. In adults, the most recognized form is chronic arthritis, especially in the carpal joints, with swelling, stiffness, and trouble getting around. In kids, CAE can cause encephalomyelitis, a progressive neurologic disease that often starts with weakness or incoordination and can advance to paralysis. Some goats also develop indurative mastitis, often called a hard udder, or chronic lung inflammation.

CAE matters not only because it can reduce comfort and productivity, but also because infected goats may silently spread the virus within a herd. That is why your vet may talk with you about both the individual goat and the larger herd plan. A positive test does not always mean a goat will become sick, but it does mean herd management decisions become important.

CAE is caused by caprine arthritis encephalitis virus (CAEV), a small ruminant lentivirus. The virus infects goats for life and may stay quiet for long periods before signs appear. Not every infected goat becomes ill, which is one reason CAE can move through a herd without being obvious at first.

The most important route of spread is from an infected doe to her kid through colostrum and milk. That is why herd control programs often focus heavily on kid management right after birth. Cross-species transmission with closely related sheep lentiviruses has also been described, especially when sheep and goats share milk-feeding or close management systems.

Adult-to-adult spread can also happen through close contact and management practices that expose goats to infected blood or secretions. Shared needles, tattoo or dehorning equipment, and poor biosecurity may increase risk. CAE has been reported most often in intensively managed dairy goat populations, but any breed can be infected if exposed.

Your vet usually starts with a physical exam and herd history. Joint swelling, chronic progressive lameness, a hard udder, or neurologic signs in a young kid can raise concern for CAE, but these signs are not unique to this disease. Your vet may also ask about recent kidding, colostrum practices, new herd additions, and whether sheep are housed with goats.

The most common way to confirm herd exposure is serologic blood testing, usually with ELISA or AGID. These tests look for antibodies rather than the virus itself. A positive result supports infection or exposure, but it does not predict exactly which goats will become sick. In very young kids or newly infected animals, timing matters because antibodies may not yet be detectable, and maternal antibodies can complicate interpretation.

In some cases, your vet may recommend additional testing to rule out other causes of lameness or neurologic disease. That can include joint fluid evaluation, radiographs, CBC and chemistry testing, or necropsy and histopathology if a goat dies or is euthanized. For herd planning, repeated whole-herd or risk-based testing is often more useful than a single one-time test.

Preventing CAE is mostly about herd management, because there is no vaccine and no treatment that clears infection. The biggest prevention step is reducing kid exposure to infected colostrum and milk. In herds working toward CAE control, kids are often removed at birth and raised on heat-treated colostrum and pasteurized milk, or another feeding plan your vet recommends.

Regular testing and herd segregation are also important. Your vet may suggest screening new additions before entry, retesting at planned intervals, and separating positive from negative groups when feasible. Closed-herd practices, careful record keeping, and avoiding commingling with untested goats or sheep can help lower risk.

Good biosecurity matters every day. Use clean needles, avoid sharing blood-contaminated equipment between goats without proper disinfection, and review procedures around tattooing, dehorning, and other management tasks. If your herd has CAE, your vet can help you choose between a control plan, long-term segregation, or a more aggressive test-and-cull approach based on your goals, herd size, and budget.