Todayโs path rounds are on ๐๐๐ซ๐๐ฌ๐๐๐ซ๐ข๐ฌ ๐๐ช๐ฎ๐จ๐ซ๐ฎ๐ฆ!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐๐ซ๐๐ฌ๐๐๐ซ๐ข๐ฌ ๐๐ช๐ฎ๐จ๐ซ๐ฎ๐ฆ is a type of ๐๐ฌ๐๐๐ซ๐ข๐, or roundworm, that affects the intestine of horses. These worms can get up to 50cm long!
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
This is most common in young horses, particularly foals and yearlings.
๐๐จ๐ฐ ๐๐จ ๐๐ง๐ข๐ฆ๐๐ฅ๐ฌ ๐ ๐๐ญ ๐ข๐ง๐๐๐๐ญ๐๐?
Parascaris has a ๐๐ข๐ซ๐๐๐ญ ๐ฅ๐ข๐๐๐๐ฒ๐๐ฅ๐, meaning that there are no other creatures involved in its transmission. Female worms in the intestine produce eggs, which are shed in the feces. Horses ingest feed contaminated with these eggs, which travels to the colon. In the colon, the eggs hatch into larvae which burrow into the colon wall and enter the blood stream. From there, the larvae migrate to the liver, then to the lungs, where they are coughed up and swallowed. When they reach the intestine, they mature and form adult worms.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
One of the first issues with Parascaris is the fact the larvae migrate through the lungs. In the lungs, the movement of the larvae can cause multiple small hemorrhages and pneumonia. This can lead to coughing, secondary infections and other respiratory issues.
In the intestine, heavy worm burdens can completely or partially block the flow of intestinal contents through the gut. This can lead to reduced weight gain in forms, inappetence, colic, ๐ข๐ง๐ญ๐ฎ๐ฌ๐ฌ๐ฎ๐ฌ๐๐๐ฉ๐ญ๐ข๐จ๐ง (telescoping of the intestine, see our previous post!) and in some cases even rupture of the intestine.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
Ascarid infection can be diagnosed by a ๐๐๐๐๐ฅ ๐๐ฅ๐จ๐๐ญ, where the number of ascarid eggs in the feces is counted. However, because you are only counting the eggs, this only tells the veterinarian about the number of female worms in the intestine, not the total population. To better appreciate the extent of infection, ultrasound is used to visualize the worms directly, and get a sense of how they are affecting the gastrointestinal tract.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐? ๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ฉ๐ซ๐๐ฏ๐๐ง๐ญ๐๐?
If the foal is presenting with colic symptoms, treatment can either be done surgically to remove the worms, or with high doses of ๐๐ง๐ญ๐ก๐๐ฅ๐ฆ๐ข๐ง๐ญ๐ข๐๐ฌ (dewormers). Routine fecal exams to look at numbers of eggs, and targeted deworming protocols, are the best bet for preventing these worm populations from getting out of control.
๐๐ก๐จ๐ญ๐จ๐ฌ
1-3) Examples of intestines with large numbers of ascarids inside.
4) An example where the intestine ruptured due to the large number of ascarids.
5) A cross-section of an ascarid on histology. They have organs just like animals do!
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 2. Sixth Edition.
Nielsen, M.K. Ascarid-associated colic in horses. Merck Veterinary Manual 2019.
Photos 1-3 courtesy of University of Calgary Diagnostic Services Unit.
Photos 4-5 courtesy of Noahโs Arkive.
