Understanding CAE and CL in Goats

When it comes to goat health, there are many concerns that owners of these loveable ruminants might have. CAE and CL in goats just might be on the top of the list of dreaded goat diseases. Many goat owners know all about these diseases and take active steps to avoid having them become a problem. But if you’re new to goats or you’ve never heard of them, here is some useful information.

What are CAE and CL?

These are two separate diseases that are common among goat herds worldwide. CAE is caused by a virus and CL by a bacterium. They are very different diseases, so let’s look at each separately:

CAE = Caprine Arthritis Encephalitis: a viral infection often manifested as arthritis in adult goats and, less commonly, as progressive inflammation of the brain (encephalitis) in kids. It is most often found in dairy goat breeds and sometimes in sheep.

CL = Caseous Lymphadenitis: a chronic, contagious bacterial infection characterized by abscesses near the lymph nodes, usually on the neck or near the udder. It is commonly found in goats and in sheep, and sporadically in horses, cattle, camelids, swine, fowl, and even people. There are two forms of the disease: The external (skin) form and the internal (organ) form.

How prevalent are CAE & CL in goats?

CAE — It is estimated that between 38% and 81% of dairy goats in the United States test positive in CAE blood screening tests, but only 20-30% of these infected goats develop symptoms. It is uncommon in meat or fiber goats.

CL — CL is not as prevalent as CAE in North America, only infecting about 8% of the goat population. However, that rate increases to around 22% in older goats. Once one animal in a herd is infected, it is likely to spread to the majority of the herd.

How are CAE & CL in goats transmitted?

CAE — The most common way that CAE is transmitted is from infected dams through their colostrum and milk-fed to their kids. However, the disease can also be spread through direct contact and can even happen through exposure to contaminated clothes or utensils used for feeding, watering, and milking, as well as through contaminated needles.

CL — CL is most commonly transmitted from one infected animal to another through breaches in the skin. Contaminated milking machines, shearing and grooming equipment, and flies are all pathways for transferring the disease. Occasionally, it can enter across mucous membranes from inhaling the bacteria. The bacteria can live for months to years in the soil, even in dry climates.

What are the symptoms of CAE and CL?

CAE — The most common symptom in adult goats is arthritis, particularly in the knee but also in other joints. Kids as young as six months may show signs of arthritis, too, but this is not as common. The onset of arthritis may be gradual or may be sudden, but it is almost always progressive and results in lameness. Goats that are affected will also have poor hair coats and declining conditioning, and adults may develop pneumonia. 

The encephalitis symptoms, most often seen in kids two to four months old, will include weakness, loss of bodily control, head tilting, paddling, and blindness. Does infected with CAE may develop mastitis or “hard bag” and decreased milk production.

CL — The external form first begins as enlarged lymph nodes, growing to one to two inches in diameter. Eventually, the node may rupture, releasing a very contagious greenish-white pus. 

The internal form involves the enlargement of lymph nodes deep within the body that may impinge upon the surrounding organs. The most common sign of internal infection is weight loss or slow to minimal weight gain in younger animals.

What are your treatment options?

CAE — There is no treatment that will cure CAE in goats, so culling affected animals from the herd or at least isolating them from the rest of your goats is recommended. Regular foot trimmings, additional bedding, high-quality feed, and administration of pain medications can help affected animals feel more comfortable.

CL — CL is not considered a curable disease and culling of infected animals from the herd is recommended. However, if an animal has a strong economic or emotional value, there are several treatment options that can prolong the animal’s life and provide comfort while minimizing the transmission of the disease to other animals. 

Lancing and draining the abscesses, flushing with an antiseptic solution, and packing the cavity with gauze is a common treatment. Surgical removal of infected lymph nodes and, more recently, the injection of antibiotics into the nodes are other options. Sanitizing all materials that come into contact with the infected animal is crucial to avoid spreading the disease.

How do you prevent CAE & CL in goats?

CAE — Keeping CAE out of your herd is the best approach. You can do this by keeping a closed herd, meaning you run a blood test on all your animals annually and only allow contact with goats that you know have been tested and received a negative test result. Require a negative CAE test result before purchasing a new animal or before bringing any outside animal onto your property.

Once CAE is found in your herd, there are several steps you can take to keep it from spreading:

• Separate kids from infected dams immediately upon birth and either pasteurize and bottle feed the colostrum and milk or only feed them milk from uninfected dams.
• Quarantine infected animals and keep them completely separate from your herd. Disinfect any items that have been in contact with the infected animal before they come in contact with uninfected animals including water buckets, milk stands, and equipment, feed tubs, etc.
• Cull infected animals from the herd.

CL — The best way to prevent CL in a disease-free herd is to keep the herd that way. Carefully screen any new animals before you buy a goat, looking for enlarged lymph nodes. Once CL is found within a herd, the following methods will reduce the likelihood of it spreading to other animals:

• Keep infected animals separate from the rest of the herd.
• Disinfect all equipment and materials that come in contact with the infected animal.
• Practice aggressive fly control.
• Vaccinate healthy and infected animals to minimize the spread of the disease. Vaccinations will not eliminate the disease completely and are not generally recommended for healthy herds with no infected animals. 
• You can screen for CL by conducting a blood test. Vaccinated animals will test positive on a blood test since they will have developed the antibodies needed to fight the disease.

While CAE and CL are not curable, they are treatable but it’s imperative that once found, steps are taken to minimize the spread of disease. The old saying, “An ounce of prevention is worth a pound of cure,” is certainly true here. Annual CAE testing and CL screening, as well as avoiding contact with infected animals, are the best ways to keep these dreaded diseases out of your beloved herd.

________________________________________

Bibliography:

• http://www.cfsph.iastate.edu/Factsheets/pdfs/caprine_arthritis_encephalitis.pdf
• https://www.merckvetmanual.com/generalized-conditions/caprine-arthritis-and-encephalitis/overview-of-caprine-arthritis-and-encephalitis
• https://www.merckvetmanual.com/circulatory-system/lymphadenitis-and-lymphangitis/caseous-lymphadenitis-of-sheep-and-goats?query=CL
• http://veterinaryextension.colostate.edu/menu2/sm%20rum/Caseous%20Lymphadenitis%20in%20Small%20Ruminants.pdf
• https://pdfs.semanticscholar.org/3263/5364556cbbd8ce8c57712852eb1eab5c30a2.pdf

And thank you to Dr. Jess Johnson from Mountain Rose Veterinary Services for additional information.

Originally published in the Goat Journal 2020 special subscriber issue — Goat Health, From Head to Hoof — and regularly vetted for accuracy.