Toxic PlantsPossibly Pretty but Don’t Touch or Eat

Bob Morgan, DVM

Type of Problems for

Horses1. Mechanical Irritation

2. Internal Poisoning

3. Unexpected Consequences

Mechanical Irritation

Foxtail Barley

Mechanical Irritation

Filaree

Mechanical Irritation

Bristle Grass(setaria)

Mechanical Irritation Yellow Star Thistle

Mechanical Irritation

Internal Poisoning

Internal Poisoning(cases in descending order)

CAHFS 1990-2007

Oleander

Oleander 1. All parts of plant are toxic 2. Plant contains Oleadrin(a cardio-toxin) 3. ~ 20 Leaves can be fatal to adult Eq. 4. Signs of ingestion may include: depression, weakness, irregular heartbeat, diarrhea, and sudden death.5 Immediate medical intervention is

imperative. Bring a sample of the plant!!

Oleander-TreatmentECG exam

Cardiac supportive drugs

IV fluids

Gastric lavage and adsorbents

Yellow Star Thistle

Yellow Star ThistleToxic principle is a complex compound that “liquifies” a portion of the brain which controls prehension.

Clinical signs include: weakness, lethargy, and incoordinted actions of the lips and tongue.

Yellow Star Thistle

1. Most cases die of starvation.2. No effective treatment.3. If on YST pasture, feed aggressively.4. ~600# of plant causes clinical signs

Pyrrolizidine Alkaloid Toxicity

Common Groundsel Fiddleneck

These plant are often incorporated in first cutting hay from California

Horses will not graze these plants

Pyrrolizidine Alkaloid Toxicity

Inspect hay for signs of PA containing plants.

PA Toxicity

1.Weight loss2. Lethargy3. Poor Appetite4. Icterus (Jaundice)5. Dark colored urine

Toxicity can occur with ingestion of as little of 12# of plant over time.

PA ToxicityPrognosis depends severity of

liver damage(liver fibrosis).

No specific treatment.Bloodwork, liver biopsy, and

behavior will aid in judging severity.

.

Unintended Consequences

Non-toxic weeds: dandelion, filaree, red clover, and mallow can concentrate sugars and fructans posing a risk for laminitis.

This can also be true of other pasture grasses on warm afternoons and after a heavy frost.

Restrict laminitis prone Eq. from these pastures or use grazing muzzle.

Unintended Consequences

Acorns/Oak

All parts of oak contain tanins/phenolswhich can lead to GIupset and colic; can be problem for EQ predisposed to laminitis.

Large amounts consumed for 2-3days in a row or longer are problematic

Take Home PointsProvide adequate, good quality feed.

Identify and remove known toxic plants.

If poisoning is suspected, contact the clinic. The patient and the plant should be examined.

Extra Credit

Extra Credit