Lecture 6 - Cardiac and pulmonary toxicants

How do cardiac glycosides cause toxicity?

Inhibit NaK ATPase pump in cardiac muscle

What are the clinical signs of cardiac glycosides?

Almost every type of arrhythmia described

How do you treat cardiac glyoside toxicity?

-IV fluids - do NOT use calcium containing fluids

-Monitor and correct arrhythmias as they occur

Digibind (Digoxin) - antidote

What are the sources of cardiac glycosides?

-Oleander

-Foxglove

-Lily-of-the-valley

-Broad-leaved milkweed

How do Bufo toads cause toxicity? What two species are toxic?

-Eat or lick compounds secreted from glands

-Rhinella marina and Incilius alvarius

How are Photinus spp. (fireflies) toxic?

Lucibufagens (related to cardiac glycosides)

How do grayanotoxins cause toxicity?

Bind to sodium channels and cause cells to maintain a state of prolonged depolarization

What are grayanotoxins found in?

-Rhododendron

-Azalea

-Laurels

-Japanese pieris

What signs does white snakeroot cause?

-Congestive heart failure

-ECG changes

What does white snakeroot toxicity cause in horses?

-Myocardial degeneration, necrosis and fibrosis

-Residual circulatory dysfunction

What compound makes avocados toxic? What does it cause?

-Persin

-Causes mastitis and cardiac failure

What does an overdose in albuterol activate?

Beta-1 and Beta-2 agonists (normally only beta-2 activated)

What are the clinical signs of albuterol toxicity?

-Tachycardia

-Hypokalemia

What is the treatment for albuterol toxicity?

Propranolol (non-selective beta blocker)

What are the clinical signs of phenylpropanolamine (PPA) toxicity?

-Tachycardia

-Hypertension

-Panting

-Piloerection

-Tremors and seizures

What is the treatment for phenylpropanolamine (PPA) toxicity?

-Emesis and activated charcoal if caught early enough

-Drugs that cause vasodilation (Ace/chlorpromazine or nitroprusside)

-Atropine contraindicated even with bradycardia (since they are hypertensive)

How does paraquat cause toxicity?

Concentrates in lungs and forms a free radical

What signs does paraquat toxicity cause?

-Caustic effects on GI tract

-Renal failure

-Progressive pulmonary fibrosis

What is the treatment for paraquat toxicity? Why should you not give oxygen?

-Aggressive decontamination

-Do NOT administer oxygen = increases free radicals and pulmonary damage

What are the potential causes of acute bovine pulmonary emphysema and edema?

-Tryptophan in lush pastures and corn

-Perilla ketones from purple mint

-4-ipomeanol from moldy sweet potatoes

How does tryptophan cause damage in cattle?

Destroys club cells and type-I pneumocytes

What are the signs of fog fever?

-Dyspnea, rapid breathing

-Feet wide, head and neck extended and lowered, flared nostrils

-Afebrile pneumonia

-Muffled, consolidated lung sounds

-Exercise intolerance

How do purple mint and moldy sweet potatoes cause toxicity?

Toxic to type I pneumocytes

What does hydrogen sulfide (H2S) toxicity cause?

-Loss of smell (anosmia)

-Paralyzed respiratory center

How is hydrogen sulfide toxicity treated? What should you not do?

-Fresh air and oxygen

-Never enter manure pits

How does teflon (polytetrafluoroethylene) cause toxicity? In what species?

Seizures, acute pulmonary edema, pulmonary hemorrhage, and congestion in birds

What type of petroleum distillates are toxic?

Low viscosity, lightweight, volatile hydrocarbons

What does petroleum distillate toxicity cause?

Aspiration and chemical pneumonitis