Fall Panicum Grass and Liver disease

“Panicgrass” – Fall Panicum toxicosis in horses.

In 2004, our practice was involved in documenting an important toxin for horses—fall Panicum (Panicum dichotomiflorum) grass.  This common native grass has been fed to horses in hay and in pasture probably since the Europeans first brought horses to our area.  But, while we know that it doesn’t cause illness all the time, certain growing conditions can cause it to become toxic, as it did in Nokesville, VA in 2004.  We don’t know what triggers the grass to become toxic, but we do know that it sometimes does become toxic, and the conditions are right this year. This study proved the hepatotoxicity: http://www.ncbi.nlm.nih.gov/m/pubmed/17186859/

Currently, there are several cases of liver disease in Fauquier, Clark and Loudon counties that appear to be from grazing Panicum grass in the pasture. Some signs of toxicity from eating the grasses includes: decreased appetite, lethargy, somnolence (unusual periods of sleepiness), mild colic, or neurological signs. Some horses have no symptoms at all.

If you have this plant in your pasture or if you find it in your hay cut this year, you may want to have your horses tested for liver disease; this involves a simple blood draw.  Call us at 703-754-3309 if you would like us to consult on a case you think might be panicum toxicosis, or if you just would like blood work on your horse to be sure.   You can also consult your County Extension agent if you need help with plant identification.



Panicum grass


Close up of Panicum seed heads.


Base of Panicum grass.


Equine Colic, Horse Colic

Equine Colic

Colic: the dread of every horse owner. But what are all these different types of equine colic you have heard us talking about? Colic is a general term for gastrointestinal pain, and there are many variations of colic in horses. There four basic problems that cause pain in the abdomen: stretching (from gas or impacted feed material), displacement of the intestine out of normal position, lack of oxygen (ischemia), or ulcerations. All these conditions are painful as you might imagine.

Gas colic: the most common type of colic. General intestinal spasms/cramping, this type usually resolves with flunixin (Banamine), and controlled re-feeding. Usually the horse feels better quickly after treatment.

Impaction colic: a blockage of feed/fecal material in the GI tract (“constipation”). This type of extremely common in cold weather when horses are not drinking enough water. Usually these colics can be treated on the farm with water and laxatives such as mineral oil via a nasogastric tube. Occasionally horses are so dehydrated they need further support with IV fluids. If the impaction doesn’t resolve with these steps, sometimes surgery is needed to open the intestine and remove the blockage.

Displacement: a movement of part of the colon out of its normal position. Sometimes these will go back into the correct position with pain control and fluids, but often the horse can need surgery.

Strangulating lipoma: usually seen in older horses, a small fatty tumor gets wrapped around a part of the small intestine and blocks it off, causing the blood supply to be cut off to that part of the intestine (ischemia). Often you will see lots of fluid and feed material (reflux) coming off the nasogastric tube. This is a surgical colic.

Torsion: this is what horsemen refer to as a “twisted gut.” The large colon is twisted on itself and blood supply is cut off to a large portion of their colon. Horses are extremely painful, and it can be very difficult to keep them on their feet. When this type of colic is diagnosed, the horse needs to get to surgical facility as quickly as possible. Often this colic has a poor prognosis.

Ulcers: these can occur in the stomach, or further back in the large colon. Usually the horse exhibits frequent bouts of mild colic, or may act uncomfortable especially after eating grain. These are diagnosed with endoscopy, and treated with anti-ulcer medications. For each one of these types of colic, there many other variations that could be listed and we could write many more blogs about each one. The horse’s gut is quite the complicated maze! The best advice we can give you is to NOT WAIT to call for a vet when your horse is uncomfortable. When in doubt, call!