Only Proper Testing Can Diagnose CL
|There seems to be much
confusion in the industry about Caseous Lymphadenitis (CL). Many producers
believe that every abscess on a goat is caused by CL.
CL is caused by Corynebacterium pseudotuberculosis. It is a chronic, recurring disease characterized by slow developing abscesses which may occur at the point of entry into the skin or in the lymph nodes. The disease may also spread via the circulatory or lymphatic system to internal lymph nodes or organs.
In goats the exudate (or puss) is usually odorless, soft, pasty, and greenish yellow to white in color.
You might be surprised to learn that there are actually many organisms that can cause abscesses on goats. These organisms are classified as pyogenic organisms.
Specifically, the abscess causing organisms are Actinobacillus lignieresii, Actinomyces pyogenes, Corynebacterium pseudotuberculosis, Corynebacterium pyogenes, Dermatophilus sp., Pasteurella multocida, Staphylococcus albus, Staphylococcus aureus, and Streptococcus sp.
In Texas our pastures are full of thorny trees, brush, cactus, and vines. Then there are the biting snakes and insects. Many of these plants and animals harbor pyogenic organisms in their mouths or on their thorns.
When a goat (or human for that matter) gets scratched, poked, or bitten unwelcome visitors are given access to an environment where they can grow and thrive causing superficial abscesses at the wound site.
Unfortunately, CL abscesses can occur at the same locations, so you cannot rule out CL based on the location of the abscess. In fact, the organism that causes CL can initially infect the animal through a thorn wound.
To complicate matters at least one other organism, Actinobacillus lignieresii, causes a nearly identical abscess of the lymph nodes, so you cannot necessarily confirm CL by the presence of lymph node abscesses.
CL abscesses do not typically contain smelly exudate. If you lance an abscess and the smell almost knocks you off your feet, you can probably assume the culprit is something other than CL. However, many other organisms cause abscesses with odorless exudates, so you cannot confirm CL by the lack of odor.
Exudates come in many consistencies and colors. I have drained abscesses with clear fluid, milky fluid, green paste, cream paste, and white paste. If the exudate is watery it is a pretty safe bet CL isn't your problem, but many organisms cause an exudate that is indistinguishable from CL, so appearance alone does not confirm CL infection.
A blood test is available for CL, however, it only confirms the presence of antibodies, not the infectious agent itself. False positives and negatives are common with this test.
The only way to obtain a definitive diagnosis of CL is to submit a sample of fresh exudate aspirated from an abscess to your vet for bacteriological examination. Corynebacterium pseudotuberculosis can easily be isolated, and a diagnosis confirmed.
It should be noted that in some cases more than one pyogenic organism will be present in the sample. This happens when the abscess is caused by multiple organisms.
Over the years I have lanced numerous abscesses, however, only one of the animals developed a second abscess. That particular animal developed numerous abscesses, and I eventually had the exudate cultured revealing that he was in fact infected with CL. I didn't allow any of his abscesses to drain on their own, and was able to prevent the spread of the disease.
The other abscesses were either caused by other organisms or perhaps the description of CL as a chronic, recurring disease is inaccurate. Some articles I have read make claims that 70% to 90% of abscesses (depending on who you want to believe) are caused by CL.
My own experience has been that most abscesses are caused by wounds infected with other organisms. Your own experience is probably going to depend on whether you have CL in your herd or not, how you treat infected animals, and the prevalence of things that can cause wounds on your goats in their pasture.
If you really want to know, I suggest you have the proper test performed.
|This page updated 08/09/07|