Equine Toxicology

Question 1

• Progressive weight loss
• Elevation in sorbitol dehydrogenase, lactate, alkaline phosphatase and decrease in albumin.
• Abnormalities in hepatic cell division, resulting in large hepatocytes (megalocytosis)
• Triad: biliary hyperplasia, fibrosis, megalocytosis
• Peri-portal fibrosis, megalocytsis, and biliary hyperplasia

Answer 1

Pyrrolizidine alkaloid Crotalaria spp (plant)

Question 2

• Myelomalacia of the lower spinal cord - pelvic limb in coordination and urine dribbling
• No specific treatment

Answer 2

Sorghum

Question 3

• Coccidiostat in feedstuff of cattle
• Highly toxic for horses (10-15 times dose lower than for cow)
• Cardiomyopathy and myocardial necrosis
• No quick and easy antidote.
• Treatment trying to empty the intestinal tract using mineral oil, activated charcoal and fluid therapy

Answer 3

Monensin Ionophore

Question 4

• Arrhythmias

Answer 4

Cardiac glycoside Oleander

Question 5

• Sudde flexion (contraction of the lateral extensor tendons): muscle atrophy (lateral thigh, gluteal).
• Horse backed up: spasmodic hyperflexion hind limb resulting in high-stepping gait

Answer 5

Sweet pea Stringhalt
Lathyrus spp

Question 6

• Not understood pathogenesis
• Mycotoxin affecting the long myelinated nerves in the hind limbs has been suggested

Answer 6

Flatweed
Australian stringhalt
Hypochoeris radicata

Question 7

• Laminitis and colic

Answer 7

Black walnut

Question 8

• Acute hemolytic anemia
• Lethargy, anorexia, dyspnea, coffee-colored urine, and icterus
• Horses seem to eat leaves when branches are available (storms)
• The plant contains an identified hemolysin in wilted leaves.
• Ingestion can be fatal.

Answer 8

Red maple
Acer rubrum

Question 9

• Liver disease after chronic exposure

Answer 9

Groundsel
Senecio

Question 10

• Blister Beetle toxicity
• Mucosal irritation, resulting in colic and cystitis
• Hypocalcemia
• Endotoxin shock and renal failure (renal tubular damage) and cardiac arrhythmias
• Dead, colickIng, in cardiovascular shock.
• Vesicles form in the mouth and tongue and if live enough watery feces.

Answer 10

Cantharidin

Question 11

• Blister Beetle toxicity
• Mucosal irritation, resulting in colic and cystitis
• Hypocalcemia
• Endotoxin shock and renal failure (renal tubular damage) and cardiac arrhythmias
• Dead, colickIng, in cardiovascular shock.
• Vesicles form in the mouth and tongue and if live enough watery feces.

Answer 11

Cantharidin

Question 12

• Megalocytosis, fibrosis, and biliary hyperplasia of the liver (liver failure)
• Contain pyrrolizidine alkaloids as groundsel, ragwort, and senecios
• Secondary photosensitization as well as hepatic damage (cumulative and progressive)
• Treatment: supportive care for liver failure
• Poor prognosis

Answer 12

Pyrrolizidine alkaloid
Fiddleneck (Amsinckia intermedius)

Question 13

• Nigropalladial encephalomalacia (loss of the globus pallidus and substntia nigra, and extrapyramidal nuclei which control muscles of pretension
• Tremors and dystonia of the lip, muscles and tongue.

Answer 13

Yellow Star thistle

Question 14

• Fungi that create dicumarol, a warfarin-like toxin
• Inhibits Vitamin K that interferes with factors II, VII, IX, X.
• Best test: Prothrombin tine (PT).

Answer 14

Dicumarol
Moldy sweet clover

Question 15

• Hepatotoxicity

Answer 15

Anabaena, Aphanizomenon and Microcysts
Blue-green algae