Todayโs path rounds are on ๐ฐ๐๐ซ๐๐ฅ๐๐ฌ!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐๐ซ๐๐ฅ๐๐ฌ is a condition caused by the larvae of flies migrating in the skin. Once in the skin, these larvae form a nodule with a hole to the external skin surface to allow them to breathe. Gross.
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
We most commonly see this disease in cattle!
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
There are two main species of fly that cause this disease, ๐๐ฒ๐ฉ๐จ๐๐๐ซ๐ฆ๐ ๐๐จ๐ฏ๐ข๐ฌ and ๐๐ฒ๐ฉ๐จ๐๐๐ซ๐ฆ๐ ๐ฅ๐ข๐ง๐๐๐ญ๐ฎ๐ฆ. Both of these flies lay their eggs onto the legs of cattle. The eggs will hatch into larvae, which will burrow into the skin without causing too many issues. These larvae are initially looking for somewhere warm within the cow to hang out over the winter! H. bovis likes to live in the fat near the spinal cord, while H. lineatum likes to live next to the esophagus. In the spring, these larvae migrate to the skin along the back of the animal, and form a nodule. This nodule has a little hole in it that allows them to breathe. Eventually, the larvae will have matured enough to leave their little home, fall off the cow into the soil, and develop into a fly.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
The nodules of the larvae can be painful, but generally this isnโt enough to cause big issues for the cow. The biggest problem is primarily economic, because these nodules can decrease both the carcass value and the hide value of the animal at processing. So for producers, these little tiny warbles can be a big deal!
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
Typically this disease is diagnosed by squeezing the nodule to pop out the larvae. That pretty much confirms the diagnosis!
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐?
These larvae can be killed by our typical insecticide products, including pour-on products that a producer might apply to the back of the cow. The timing is the most important aspect fo treatment, because the cattle should be treated immediately following fly season. This allows any larvae that did burrow into the cow to be killed long before they will do their spring migration to the skin. Treating them in the spring once they have already moved is far too late!
๐๐ก๐จ๐ญ๐จ๐ฌ
1) What Hypoderma larvae look like.
2-4) Skin samples with the larvae in their little homes.
5) A larvae hanging out next to the esophagus. What species would this larvae be?
6) A poor cow with several Hypoderma nodules, along with the larvae removed from them 
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 1. Sixth Edition.
Reichard, M.V. Hypoderma spp. Merck Veterinary Manual 2015.
Photo 1, 2, 6 ยฉ Wikimedia Commons contributors Lucyin, Wadudu licensed under CC BY 3.0.
Photos 3-5 ยฉ Noahโs Arkive contributors King, Tyler licensed under CC BY-SA 4.0.
