Caseous Lymphadenitis in Sheep and Goats: avoid it before you get it
When we look for a used car, we often ask for the Carfax®. This report tells you the history of the vehicle and gives you a vision of what potential issues you may run into in the future. When purchasing animals at market or on farms, use the precautionary principle for each one of your potential purchases. You should ask for the history of these animals and inspect them thoroughly. There are some diseases that are increasingly more common since many producers have limited information on the importance of biosecurity measures. By implementing these measures you can prevent the entrance of pathogens such as virus and bacteria onto your farm. In this article we will talk about Caseous Lymphadenitis (CL), a common disease people often introduce to local herds when purchasing sheep and goats as replacements.
Introducing the pathogen
Caseous Lymphadenitis is a bacterial infection that affects lymph nodes of sheep and goats. The bacterium responsible for this disease is Corynobacterium pseudotuberculosis. This bacterium is highly contagious and resilient under Florida climatic conditions. It survives in the soil for months to years even in direct sunlight. This microbe causes the development of lymph node abscesses two weeks after initial exposure in most cases. It can also appear several months after exposure in some animals.
Economic losses associated with CL include death of infected animals, carcass condemnation and loss due to trimming infected areas in the carcass, hide and wool loss, loss of sales for breeding animals, and premature culling of infected animals.
Seen most commonly on goats – Infected lymph node abscesses are visible (enlarged) under the skin. Abscesses can grow to a size of 1-2 inches in diameter. Most commonly, infected animals will have abscessed lymph nodes on the jaw, in front of the shoulder and in the flank.
Eventually the skin surrounding the abscess will break and release thick green and white pus. When this happens, the potential for herd contamination increases dramatically.
Lymph nodes deep within the body become infected. The nodes in the thoracic cavity are most commonly involved. Swelling and abscessing of nodes create discomfort to the animal to the point that the animal will start losing weight (in older animals) or slow to minimal weight gain (in younger animals). At slaughter, the carcasses of these animals are condemned.
Caseous lymphadenitis can spread via contact with bodily fluids of infected animals, particularly nasal discharges, which can contaminate surfaces in common areas such as feeders and waterers. Shearing equipment, combs and other tack contaminated with pus from the abscesses can also spread the bacterium. Aside from sheep and goats, this disease can sometimes be transmitted to other farm animals such as horses, cattle, swine, camelids and even deer. It is considered zoonotic as well, since humans can contract it.
Caseous lymphadenitis is not considered a curable disease. Treatment of this disease requires the help of a veterinarian who will design a program to reduce the spread of CL. Culling and isolating infected animals, treating abscesses and the use of antibiotics are key strategies to eliminate this disease from your farm.
Invest in Biosecurity
- Create a quarantine area on the farm. This area should be used to place new arrivals under observation before releasing them into your herd/flock. Do not share feeders, water troughs and other equipment with general flock equipment.
- Know what you are purchasing. Screen newly purchased animals for signs of CL. Examine newly purchased animals by looking for previous scarring from healed abscesses around jaw, shoulder and flank regions.
- Control your fly populations. Flies feed on bodily fluids and can spread CL around the herd/flock.
- Disinfect equipment that is used for common maintenance – shearing equipment, combs, milking equipment, etc.
- Vaccinate against CL – the vaccine will not eliminate infections, but will reduce the incidence of abscesses in infected animals.
- Isolate animals with abscesses until the infection is resolved. Work with your veterinarian on a plan for reentry of infected animals to the general population.
- Remove barbed wire, nails and other potentially hazardous items from common areas to decrease injury and potential transmission of CL by abscess ruptures.
Give us a call!
For more information on sheep and goat diseases or management of your herd/flock, contact the UF/IFAS Extension Hardee County Office at 863-773-2164.