Todayโs path rounds are on ๐๐ฅ๐๐๐ค๐ฅ๐๐ !
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐ฅ๐๐๐ค๐ฅ๐๐ is a form of ๐ ๐๐ง๐ ๐ซ๐๐ง๐จ๐ฎ๐ฌ ๐ฆ๐ฒ๐จ๐ฌ๐ข๐ญ๐ข๐ฌ (muscle infection causing death of tissue) caused by bacterial infection. This disease is typically characterized by โbubblesโ in the muscle, from the bacteria producing gas.
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
This disease is most commonly seen in cattle, although other species can get it as well.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
Blackleg is caused by ๐๐ฅ๐จ๐ฌ๐ญ๐ซ๐ข๐๐ข๐ฎ๐ฆ ๐๐ก๐๐ฎ๐ฏ๐จ๐๐ข, a type of spore-forming bacteria. Cattle will ingest spores of the bacteria in the soil as they are out grazing pasture. The spores are absorbed by the intestine, and get distributed throughout the animal in the blood. These spores like to find a home in the muscle, where they remain ๐ฅ๐๐ญ๐๐ง๐ญ (not doing much).
The spores will hang out indefinitely, without causing any issues, until there is some type of muscle damage. This damage is typically from trauma, like getting kicked by another cow, or banging against the side of a chute. This muscle injury produces an area of low oxygen supply from the blood, which stimulates the spores to proliferate. The proliferating bacteria begins producing lots of gas, which causes the characteristic โbubblesโ we see at necropsy.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
Having these bacteria proliferating is very painful, and causes a lot of inflammation. These animals are often lame and have a raging fever, and in some cases the bacterial toxins can even cause ๐ฌ๐ก๐จ๐๐ค (circulatory system failure) leading to death. In fact, it is quite uncommon for these animals to survive beyond 24 to 36 hours after first developing muscle swelling.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
Because these animals die so rapidly, often we only make this diagnosis at necropsy. The characteristic finding is muscle that smells like ๐ซ๐๐ง๐๐ข๐ ๐๐ฎ๐ญ๐ญ๐๐ซ (weird, I know) and ๐๐ซ๐๐ฉ๐ข๐ญ๐ฎ๐ฌ of the muscle. Crepitus basically means feels like bubblewrap when you poke it. Fun!
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐? ๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ฉ๐ซ๐๐ฏ๐๐ง๐ญ๐๐?
Unfortunately, treatment isnโt really viable for these animals because they die so quickly. So prevention is the best method of control! Thankfully there are very effective ๐๐ง๐ญ๐ข-๐๐ฅ๐จ๐ฌ๐ญ๐ซ๐ข๐๐ข๐๐ฅ ๐ฏ๐๐๐๐ข๐ง๐๐ฌ available, including ones that target Clostridium chauvoei. Making sure that your animals are adequately vaccinated according to your veterinarianโs recommended protocol is best!
๐๐ก๐จ๐ญ๐จ๐ฌ
1-4) Examples of bubblewrap muscle from blackleg.
5) An example of blackleg affecting the heart. Any muscle can be affected!6) What a pathologist sees under the microscope. The little blue sticks are the bacteria themselves!
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 1. Sixth Edition.
Photos 1-6 ยฉ Noahโs Arkive contributors Mendes, Doster, Libioreiro, Rech, Jennings licensed under CC BY-SA 4.0.
