Lecture 6 Flashcards
What are examples of anticoagulants and anticoagulant rodenticides
Warfarin- first generation compound; short half life
Brodifacoum- seond generation compound; long half life
Anticoagulant MOA
Inhibits vitamin K epoxide reductase and prevents formation of vit k dependent clotting factors
Clinical signs of anticoagulants
Delayed onset
Depression, anorexia, anemia, dyspnesa, nose bleeds, bleeding gums, bloody feces
Hemorrhage
Diagnosis of anticoagulants
History
Evidence of coagulopathy
Response to vit k therapy
Increased PT, APTT, or PTT with normal platelet counts
Treatment of anticoagulants
Emesis, adsorbent, cathartics
Vit K administration for long time (2 weeks to 1 month)
Possible blood transfusion if needed
Where are nitrates found
Fertilizers, plants, contamination of water
Who is susceptible to nitrate toxicosis
Pigs>cattle>sheep>horses
What does nitrate converted to nitrite cause
Vasodilation and oxidized ferrous iron in hemoglobin resulting in methemoglobinemia
Results in oxygen starvation of tissue
Clinical signs of nitrate
levels of MetHb: <10%= asymptomatic 15%= cyanosis, brown blood and membranes 50%= ataxia, seizures, coma >70%= death
How to diagnose nitrate toxicosis
Measure levels in food and water
Save plasma, serum, or eye for analysis in necropsy
Treatment of nitrate
IV methylene blue- most effective in ruminants; causes urine to become dark green
Use abscorbic acid in cats and horses
Educate farmers
Feed corn to increase nitrite reduction by rumen flora
Cardiac glycosides MOA
Come from plants- oleander, lilly of the valley, foxglove
Inhibit Na/K ATPase pump through competition with potassium for binding sites
Clinical signs of glycosides
Trembling, staggering, dypsnea
High Ca and Na and K
Tachy, arrhythmias, weak pulse
Clinical signs can depend on which plant and what part of plant is consumed
Treatment of glycosides
GI decontamination
Treat arrhtyhmias with propranolol
Treat hyperkalemia
Antidote is digoxin immune Fab fragments (digibind)
Where is cyanide found
Wilted leaves and seeds of wild black cherry, white clover, or fresh sorghum
Fertilizers, pesticides, rodenticides, fumigants, combustion
When is cyanide not toxic
When it is dry
Toxic when it is hydrogen cyanide gas
Cyanide MOA
Inhibition of cytochrome oxidase and oxidative phosphorylation
Clinical signs of cyanide
Very rapid
Cherry red blood that is slow to clot
Sudden death, dyspnea, weakness, tremors
Treatment of cyanide
- Induce methemoglobin formation with sodium nitrite to bind cyanide. Afterwards can treat MetHb
- Give sodium thiosulfate to increase formation of thiocyanate, which is non toxic
*basically just find another buddy for the cyanide besides the mitochondria
What are methylxanthines and where are they found
Caffeine, theobromine, theophylline
Found in chocolate, coffee, and medications
Methylxanthine MOA
Competitive antagonist of adenosine receptors
Cause CNS stimulation, vasoconstriction, and tachycardia
Prevents Ca reuptake leading to increased skeletal and cardiac muscle contractility
Inhibits phosphodiesterase which increased cAMP and GMP concentrations
Methylxanthine clinical signs
Vomiting, diarrhea, diuresis Hyperactivity, panting, bounce Tachycardia, hypertension Ataxia Tremors and seizures Coma Death from arrhythmia or resp failure
Diagnosis of methylxanthine
Can detect theobromine in system for 3-4 days after ingestion
Methylxanthine treatment
Gi decontamination- emesis and charcoal Monitor EKG- treat with lidocaine in dogs Treat seizures Maintain respiration Fluids
Where is gossypol found
Cottonseed- natural deterrent for insects to not eat the seed
Issue for large animals not small animals
Gossypol MOA
Accumulates in the plasma with time
Chelates iron and causes anemia
Inhibits dehydrogenase leading to low energy and stress
Clinical signs of gossypol
Weight loss, weakness, dyspnea, anemia, edema secondary to heart failure, myocardial necrosis, CHF
Dairy cows and lambs may die suddenly
Diagnosis of gossypol
History of ingestion
Cardiac necrosis, edema, vacuolization
Chemical analysis of gossypol
Treatment for gossypol
Feeding high protein diet, add vitamin A, iron, and lysine
Remove gossypol source
Where does cantharidin come from
Blister beetles or spanish flys in alfalfa hay
Who does cantharidin usually affect
Horses
MOA of cantharidin
Inhibits protein phosphatases
Irritates mucous membranes
Clinical signs of cantharidin
Colic, frequent urination, diaphragm contraction with heart beat, shock
Ulceration of oral, GI, and bladder epithelia (will see them dipping muzzles in water)
Causes cardiac toxicity
Cantharidin diagnosis
Alafala hay consumption Search for beetles in hay or stomach Hypocalcemia, increased BUN Ulceration of mm Cardiac necrosis Sudden death with no struggle
Treatment of cantharidin
GI decontamination and protection, antibiotics
