CASEOUS LYMPHADENITIS
by
Keith Smith

Known in the sheep and goat industries as "CL", Caseous Lymphadenitis is a chronic, contagious, zoonotic disease characterized by infected lymph nodes. There is no "cure".

Some breeders are almost fanatic in their fear of the disease while most producers whose livelihood depends on sheep or goats consider it an inconvenience. All agree that it must be controlled. The form that the control takes depends on the goals, capabilities and commitment of the individual producer.
Various controlled studies have shown immunization to be from 70% to 80% effective (immunize 10 goats - expose them to CL - 2 or 3 of them will contract the disease). Offspring of infected or immunized animals invariably carry antibodies at levels sufficient to prevent infection for the first three to four months of their lives.

The actual "bug" that causes CL is Corynebacterium pseudotuberculosis. The bug can enter the animal's body through small cuts or abrasions and can even pass through the mucous membranes of the mouth, nose, eyes, and genitalia. The incubation period, how long it takes for signs of infection to occur, can be from 2 to 6 months after initial exposure. The immune system of a healthy host will attempt to localize the infection by walling it off in a cyst within a lymph node. If the host is very lucky or has a very strong immune system all of the pathogens will be confined to this cyst - if not, the host will need to form more cysts to contain and control the "loose" bugs. Once a host has isolated all of the pathogens it is immune to further infection because of immunity gained through fighting the first onslaught. A severely infected host or one with a weakened or suppressed immune system will succumb to the infection.
Stress such as kidding, transportation, etc. many times will compromise the immune system sufficiently to prevent an otherwise healthy animal from fighting off the disease.

Successful encysting by the original host solves the problem for that host but... the bug, like all living things, wants to survive too. The exudate and the number of organisms within a cyst increases until the cyst bursts, usually outward through the skin of the host. This allows the bugs to spread to the ground, the walls, the feeders, the... well, you get the idea. Studies have shown that this bug can survive for long periods of time in soil, on wood stall walls, etc.

External lumps are not the only locations for these cysts to appear. The lungs and other organs which contain major lymph collection nodes can also be effected. Since sheep and goat viscera (internal organs) are not considered an economically significant item such infections, in their early stages, should have no impact on the value of the carcass. Cysts do not form within muscle, the meat that the primary carcass value is based on. External cysts or wounds do, however, reduce carcass value - any mar in the skin will decrease the pelt value significantly.

Typical locations for external abscesses include:

  • just below the ear at the jaw line
  • directly below the jaw where it meets the neck
  • in front of the shoulder
  • at the attachment between the udder and the body

What does a CL knot look like? Well, it starts out as a thumbnail sized bump on the skin and grows, usually to about the size of a golf ball, until the hair starts to fall off. Then it usually ruptures and a thick, light gray paste oozes out.

What do I do if I find a knot? First, not all cysts are CL. Most are sterile abscesses at the injection site of C/D&T immunizations - a 1/2 inch knot at an injection site that does not increase in size over a week or so is probably not anything to worry about. Other benign causes of knots are retained thorns or splinters.
Treatment of an actual CL cyst can be handled one of four ways...

  1. The entire abscess can be removed intact.
    This is a job for a qualified veterinarian, not a backyard pseudosurgeon. There are usually major blood vessels and nerves located very close to these cysts and these must be avoided if you want your goat to live a long life.
  2. The cyst can be drained.
      If you are lucky and skillful you can drain the cyst.
    • Prepare the operating area - *Everything* that comes into contact with the pus must be burned after the procedure; disposable gloves, plastic shoe covers, gauze pads, paper towels, collection bag, syringes, scalpel blades, newspaper (used as floor and wall coverings), etc. - Wear safety glasses.
    • Make sure the goat is fully restrained. A bucking, squirming goat will spread the pus like butter on bread.
    • Shave the hair off of the cyst and 3 inches around it.
    • Cut the full length of the cyst from top to bottom. Not much pus will come out at this point - this stuff is thick.
    • Collect the pus in paper towels by gently squeezing the knot. There will be a lot of it. Make sure the cyst is completely empty of pus.
    • Thoroughly wash the inside of the empty cyst with 7% iodine. Also wash the shaved area around the cyst with iodine to insure that any stray pus is removed.
    • Collect all of your disposable stuff and burn it. Don't walk around the barn with your plastic shoe covers on after the procedure - that kind of defeats the purpose of cleaning up.
    • Keep the goat isolated from the herd for 3 days, during which you'll be opening the cut every day to wash it with the iodine again.
  3. The cyst can be killed.
    Inject the cyst with 1cc (1ml) of formalin two days in a row. Formalin is a weak cousin of formaldahyde. You know... that stuff that body parts are stored in for science classes. Insert the needle (20 gauge) about 1/2 inch into the cyst and draw back on the plunger. If you get pus in the syringe the chances are about 0.999999:1 that the cyst *is not* CL - stop the procedure. If you cannot draw any pus into the syringe then the chances are about 0.999999:1 that the cyst *is* CL - go ahead and inject the 1cc of formalin into the cyst. When you withdraw the needle hold your finger (which has a plastic glove on it) over the hole for a minute or two so that the formalin doesn't leak out. Repeat the treatment the next day. Within a week or two the cyst will fall off.
  4. Dispose of the goat.
    That does *not* mean sell it at the local auction barn or to some unsuspecting breeder. If you can't find a breeder who both wants the goat and knows how to manage CL then you must destroy said goat. Bury it *deep*.

Immunization - Some producers administer a commercially prepared immunizing agent containing killed pathogens. The primary source for a "generic" agent is Colorado Serum Company. Their product, CASEOUS D-TTM can be ordered from most supply houses but is not available at this time (July 2002) because of high demand. Colorado Serum Company does not make any representations concerning this product for use in goats. This is a sheep product and any use in goats is "off label" and not approved or recommended. Colorado Serum Company may be contacted at

P.O. BOX 16428
DENVER, CO 80216
PHONE: 800-525-2065
FAX: 303-295-1923
http://www.colorado-serum.com

Autogenous vaccines prepared specifically for each producer's herd are available. Your veterinarian can contact

American Animal Health, Inc.
1401 Joel East Road
Ft. Worth, TX 76140
(817) 293-6363
Fax: (817) 293-7711
Toll-Free: 1-800-272-8338
http://www.aahinc.com

PHL Associates, Inc.
2523 J Street, Suite 203
Sacramento, CA 95616-9410
1-877-566-7722
http://www.phlassociates.com

Grand Laboratories, Inc.
44130 279th Street Box 1050
Freeman, SD 57029
1-800-843-3386 
http://www.grandlab.com

Having a goat infected with CL is not the end of the world. It is, however, something to avoid and something to manage aggressively should it occur.
As always, consult your veterinarian before beginning any treatment regimen or immunization program.