Saturday, August 14, 2010

Got Tack?

We are getting ready for our Annual Fall Tack Sale on Sept. 25 at The Farm Store Pet Adoption Fair. Thanks to the generous donations from our friends, our two yearly tack sales (Spring and Fall) raise critical funds for the rescue.

YOU can help!

How? Clean out the tack room and send those bridles, bits, pads, saddles, breast collars, reins, sidepulls, etc. our way. Donations can be dropped off during the day wit Thommie at The Farm Store (map) or in the evening with Cherie at Freshwater Stables. Thank you everyone!

Sunday, August 8, 2010

Toxic Plants in Your Hay and Pasture - Be Informed!

Plant poisoning in horses is preventable, and being able to recognize plants that are potentially hazardous will help you safeguard your horse’s health and well-being. Several poisonous plant species are common to this general area, and may be found in both hay and pasture. Also, there are numerous plants that are not poisonous per se, but are mechanically injurious, and can cause marked discomfort for your horse. Because of this, you should be particular about where and what your horse is eating.

Why are some plants poisonous?

It is generally accepted that poisonous plants have evolved toxic components as a means of protection against predators and disease. Grazing animals are only one group of plant predators, and may, in fact be incidental victims of toxins that are present as protection against insects, and microorganisms, such as fungi. On the other hand, some plants are poisonous to livestock only after they have been damaged by freezing or inclement weather or because they are infested with fungi that produce toxins. The amount of toxic material in some poisonous plants can vary due to growth stage, season, and other environmental factors. Therefore, it is often difficult to specify the amount of plant material that needs to be ingested before poisoning is evident. As a general rule of thumb, poisonous plants are not harmful only if your horse doesn’t eat them.


Plants that cause liver damage: Common groundsel, Tansy ragwort, and Fiddleneck.

Common groundsel (Senecio vulgaris):
This winter annual appears in abundance in the spring, is a common weed in gardens and along walkways, and can be a contaminant of pastures and first-cutting alfalfa. Common groundsel can be recognized by its flowers, which are clustered, tight, yellow-tipped buds that open to expose silky-white-haired seeds. The leaves are elongated, with jagged margins that have smooth edges. Smooth stems may be single or have many branches. The entire plant may vary in size from 6 to 24 inches in height. It is generally avoided by horses in pasture, unless other more palatable forage is sparse. Alternatively, pastured horses may inadvertently consume groundsel that is hidden amidst lush stands of spring grass. Most poisonings occur after ingestion of contaminated hay. Groundsel is
toxic either fresh or dried


Tansy ragwort (Senecio jacobea):
This hardy biennial plant can behave as a winter annual or as a perennial. It thrives in many soil types, from sand and gravel to clay. The flowers of Tansy ragwort are clustered at the tops of branches which arise from a single stem, and open to expose bright yellow petals, similar to daisies. The leaves have a ragged appearance, are 2 to 8 inches long, with a hairy, cobweb texture to the undersides. The mature plant ranges from 1 to 3 feet tall. It is found along roadsides and in pastures, especially in the Northcoast counties. Severe pasture contamination in Oregon has been responsible for many livestock fatalities in the past. The lethal dose for a horse is 3 to 7% of its body weight, or 30 to 70 lbs. for a 1000 lb.
horse. It is toxic either fresh or dried


Fiddleneck (Amsinkia intermerdia):
This California native annual is common to pastures and roadsides, is a common contaminant of untreated grain crops, and out hay fields, and may be found in first cutting alfalfa. The plant sprouts a flowering stalk which contains small orange-yellow flowers in a curl at the top (like a fiddle). Stems may be single or branched, dark to grayish green, with lance-shaped hairy leaves. The seeds are the most toxic part of this plant. Livestock poisonings have resulted from feeding seed-contaminated grain or grain-screenings, and hay containing dried fiddleneck plants. Inadvertent consumption in lush pasture is also possible.

Toxic Components
These three plants all contain compounds called pyrrolizidine alkaloids (PA’s). The PA’s themselves are not toxic, but are converted in the liver (metabolized) to highly reactive compounds that either cause cell death or damage. Ingestion of large amounts of PA’s in a short time results in massive liver damage, acute liver failure, and death. A more chronic syndrome is often seen with ingestion of small amounts over a longer period of time (even seasonally). In these cases, the liver is damaged a little at a time, and clinical signs are not evident until a large portion of the liver has become non-functional. This may occur 6 months to years after ingestion of the toxic plants.

Clinical Signs of Liver Toxicity and Diagnosis

Clinical signs vary, and may include behavioral changes, such as dullness, depression, aimless wandering, head pressing, and photosensitization causing sunburn of pink-skinned areas, weight loss, bleeding disorders, and jaundice of mucus membranes. Blood and urine tests and liver biopsy are useful in diagnosing liver toxicity.

Yellow Starthistle (Centaurea solsititalis):
This annual weed has become widely distributed throughout California. It is common in non-irrigated pasture, especially where overgrazing has occurred, and can be a contaminant of grass, grain, or alfalfa hay. The gray-green, cottony-leafed rosette sends up branching, woody stems topped with spiked yellow flowers. The mature plant may be 1 to 3 feet in height. Although the toxic constituent of yellow Starthistle is unknown, the entire plant is apparently toxic, either fresh or dried. Typically unpalatable and avoided in pasture, horses may acquire a taste for this plant and seek it out despite the presence of more palatable food. Contamination of hay results in inadvertent ingestion. Yellow Starthistle poisoning only affects horses, and causes an irreversible necrosis of two specific regions of the brain. A large quantity (600 plus lbs.) must be eaten, typically over a period of 1 to 3 months before poisoning is evident.

Clinical Signs and Diagnosis of Starthistle Poisoning:

Clinical signs occur abruptly and involve difficulty in eating and drinking. There may be uncontrolled twitching of the lips, and the mouth may remain open. Swallowing is not affected, but the horse cannot pick up, chew, and move food back to be swallowed. There is no treatment for this poisoning. Affected horses will die of starvation and dehydration if left unattended. Diagnosis is based upon clinical signs, physical examination, and evidence of access to the plant.

Oleander (Nerium oleander)
This common ornamental shrub bears mentioning because of its prevalence as a landscaping plant. It is not readily eaten, but poisoning of horses and other livestock has resulted from access to hardened trimmings, or when leaves are baled with hay. Bored horses might chew on plants which grow near their paddocks. A highly toxic cardioactive compound is found in all parts of the plant, especially the seeds, and the lethal dose is very small. Ingestion causes digestive disturbances, and cardiac arrhythmias. Treatment is often unsuccessful, and this type of poisoning is generally fatal.

Plants that Cause Mechanical Injury
Numerous species of grasses produce barbed seed heads (commonly call foxtails) that penetrate and can become imbedded in skin and mucus membranes. Ulceration and infection, and abscess can result. Ulcerations in the oral cavity may cause pain with eating and weight loss. Wild barley, wild oats, and yellow bristle grass are examples of barbed grasses that may be found in pasture or first cutting hay.

Prevention of Plant Poisoning and Plant Injuries

  • Provide sufficient high quality forage
  • Manage pasture to prevent overgrazing and to control weeds
  • Be knowledgeable
  • Be particular

Courtesy of UC Davis. More information available, including a list of all the poisonous species in the USA, at