Equine Toxicities Flashcards
Ability to transport ions across biological membranes
Ionophores
What are ionophores?
Lasalocoid, monensis, salinmycin
What are ionophores used for in ruminants?
Growth promotion, coccidostats
Which species are ionophores toxic to?
Horses
What is the MoA of ionophore tox in horses?
Distrubtion of mitochondria causes loss of aerobic energy production
What tissues are affected most by ionophore tox?
Muscular and neuro tissue
How soon after ionophore exposure do acute clinical signs develop?
Within 24h
What are acute clinical signs of ionophore toxicity?
Ataxia, anorexia, tremors, tachycardia, recumbency, death
What are long-term effects of ionophore toxicity?
Poor performance, exercise intolerance, arrhythmias
How does ionophore toxicity cause long-term effects?
Damage to the heart
How do you treat ionophore tox?
Check diet and remove source, no specific therapy
Used in insecticides
Organophosphates
What is the MoA of organophosphates?
Inhibits ACh-ase = accumulation of ACh @ post-synaptic receptors = excessive neurotransmitter activity
What are clinical signs of organophosphate toxicity in horses?
SLUDD signs, bradycardia, miosis
What other toxicity causes clinical signs similar to organophosphate tox and works via the same mechanism?
Carbamates
How do you treat carbamate tox?
Atropine and pralidoxime chloride (2-PAM)
What fungus is assoc. w/fescue?
Neotyphodium
What toxin does Neotyphodium produce?
Eropeptine alkaloids
What is the MoA of eropeptine alkaloids?
Dopamine agonist
What are clinical signs of fescue tox?
Prolonged gestation, placental thickening, agalactia
How do you dx fescue tox?
Empiric
How do you tx fescue tox?
Remove fescue + Domperidone
What plant causes acute hemolytic anemia in horses?
Wilted red maple
Are fresh red maple leaves toxic to horses?
No, just wilted ones
What does the wilted red maple toxin cause?
Oxidative damage to erythrocyte membranes (RBC lysis)
What are clinical signs of red maple tox?
Lethargy, dyspnea, dark-colored urine, acute renal failure
How do you treat red maple tox?
IVFT, blood transfusion, Vit C
What do blister beetles contain that is toxic to horses?
Cantharidin
Where do blister beetles live?
Alfalfa hay
What is the MoA of cantharidin?
GIT and kidney irritation
What samples can you take to ID catharidin?
Stomach or urine contents
How do you tx blister beetle toxicity?
Supportive care
What does moldy corn toxicity cause?
Leukoencephalomalacia
What toxin does moldy corn contain?
Mycotoxin fumonisin
What type of clinical signs does moldy corn tox produce?
Neuro more than liver-related
What are clinical signs of moldy corn tox?
Incoordination, blondness, head pressing, sweating, anorexia, lethargy
What toes moldy corn toxin cause in the brain?
Liquefactive necrosis and cerebral degeneration
How can you empty ionophores from the GIT of a horse?
Mineral oil, activated charcoal, IVFT
How does fescue cause reproductive failure in mares?
Prolactin suppression
Will GI or neuro signs appear first in horses affected by cantharidin (blister beetle tox)?
GI (colicking)
How do you treat organophosphate toxicity in dogs and cats?
Atropine or 2-PAM
