L6: Gastrointestinal Toxicants (Martyniuk) Flashcards
common source of zinc
pennies
NSAIDS MOA
- act on COX 1 and/or 2 pathways
- inhibit synthesis of prostaglandins (which protect gastric mucosa)
- decrease renal blood flow
- cause gastric ulceration
- uncouples oxidative phosphorylation at high doses –> increased lactic acid, metabolic acidosis
which NSAID are dogs most sensitive to?
ibuprofen
which NSAID are cats most sensitive to?
aspirin (due to lack of glucuronidation)
Which pathway, COX-1 or 2 is constitutive (always on)? What does it control?
COX-1
- homeostasis
- protection of gastric mucosa
Which pathway COX 1 or 2 is inducible? What does it control?
COX-2; mediates pain, inflammation, fever
Clinical effects of NSAID toxicity
- vasoconstrictive acute renal failure
- acute interstitial nephritis
- fluid/electrolyte imbalances
- renal papillary necrosis
- chronic renal failure
acute aspirin toxicity symptoms
- nausea, vomiting, anorexia
- fever, resp. stimulation
- depression, lethargy, seizure, coma
- acidosis with anion gap
- reduced renal flow, renal failure
chronic aspirin toxicity symptoms
- gastric ulcer
- anemia, bone marrow depression
- Heinz bodies, thrombocytopenia
Dx of NSAID toxicity
- Hx/CS
- anion gap
- inc. liver enzymes, jaundice
- dec. blood clotting, inc. bleeding time
- acute renal failure: casts, inc. BUN/creat.
Tx of NSAID toxicity
- induce emesis and activated charc.
- tx acidosis, correct electrolytes/glucose
- sucralfate or H2 blocker for ulcers
- DA or dobutamine to inc. renal blood flow
- diuresis to maintain urine flow
- dextrose w/insulin to tx hyperkalemia
misoprostol
prostaglandin analog that protects GI tract
arsenic sources
(#1 priority pollutant)
-insecticides, medicide, food production, electronics, shellfish, water
which is more toxic: inorganic or organic arsenic?
inorganic (10x)
MOA of inorganic arsenicals: ARSENITES (+3)
ARSENITES: bind to -SH groups and cause enzyme inhibition; effect protein function and are assoc. with blood problems
-cause toxicity to GI epithelium and capillary endothelium
MOA of inorganic arsenicals: ARSENATES (+5)
ARSENATES: substitute for phosphate and uncouple oxidative phosphorylation ; assoc. with mitochondrial dysfunction and disruption of electron transport chain –> CNS problems
-cause toxicity to GI epithelium and capillary endothelium
Are inorganic arsenicals absorbed/excreted rapidly?
yes for both
inorganic arsenicals is a problem mostly with what species?
cattle and dogs
signs of ACUTE inorganic arsenic poisoning
Acute exposure:
- sudden death
- abd pain, colic
- weakness
- salivation, vomiting
- diarrhea
- hypotension
- dehydration
signs of SUBACUTE inorganic arsenic poisoning
- live for 1-3d
- depressed, colic
- watery diarrhea
- PU/PD
- dehydration
- posterior paresis
- poor perfusion
lesions assoc. with inorganic arsenic toxicity
- no lesions if very high exposure
- brick red gut
- fluid GI contents
- soft yellow liver
- congested lungs
- damage to glomerulus and tubules
- no hemorrhage
Dx of inorganic arsenic toxicity
- sudden death of animal, esp. near water source
- arsenic in liver/kidney >5ppm
- arsenic in stomach/vomitus
Tx of inorganic arsenic tox.
- GI decon
- demulcents to protect injured mucosa
- chelation therapy (binds arsenic)
- fluids with B vitamins, electrolytes, dextrose for shock/urine flow
Zinc sources
galvanized metals, pennies, sunscreen, cold meds, herbals, paint, etc.
main role of zinc in body
antioxidant response; an important cofactor for enzymes used in the mitigation of oxidative stress
Symptoms of acute zinc toxicity
oxidative damage/hemolysis –> v, depression, anorexia, hemolytic anemia, jaundice, pancreatitis, lesions
in low pH environment, zinc forms zinc salts and interacts with GI mucosa to cause problems
:)
acute zinc toxicity occurs most often in which animals?
dogs, aquatic animals
chronic zinc toxicity occurs most often in which animals?
cattle
symptoms of CHRONIC zinc toxicity
bloating, d, PU, anorexia, hemolytic anemia, lamenss, lesions
Dx of zinc toxicity
- serum/liver zinc elevated
- dec. PCV, regenerative anemia
- liver/kid/pancreatic enzymes
- hemoglobinuria
- rads for hardware ingestion
Tx of zinc toxicity
- remove FB
- emesis
- fluids
- increase gastric pH**
- chelation with CaEDTA or d-penicillamine
- proton-pump inhibitors or H2 blockers
4th most common group of toxins the Animal Poison Control Center receives calls for
household chemicals:
Most to least toxic household chemicals
1) ammonia
2) toilet bowl cleaner
3) disinfectants
4) automatic dishwasher detergent
5) bleach
6) soaps/detergents
tx of soap/shampoo tox.
dilute with milk or water
-rarely fatal
tx of bleach tox.
- dilute with milk/water
- emesis, lavage (except if very caustic)
- act. charc., cathartics (except if very caustic)
- toxicity due to alkalinity*
2 types of disinfectants
Phenols
Pine oils
Phenol MOA
denatures and precipitates cellular proteins thus destroying all contacted cells
Pine oil MOA
directly irritating to mm. Cats more susceptible because detoxified by glucuronidation!
CS of phenol tox.
- corrosive burns of oral-esophageal pathway
- v, hypersalivation, ataxia, panting –> shock, arrhythmia, MetHb, hepatic/renal damage, coma
CS of Pine oil tox.
-nausea, hypersalivation, v, abd. pain, ataxia, hypotension, resp. depression, acute renal failure, pulm. edema
Tx of phenol tox.
- demulcents (milk/eggs)
- gastric lavage, emesis, act. charc. if no burns
- supportive therapy (fluids/resp. support)
- methylene blue for MetHb
Tx of Pine oil tox.
- dilute with milk, egg white, water
- emesis and lavage CONTRAINDICATED due to aspiration pneumonia
- follow dilution w/ act. charc. or cathartic
- supportive therapy (renal perfusion, acid/base and electrolyte balance)
toxicity of automatic dishwasher detergents due to:
high alkalinity
Tx of dishwasher detergent tox.
- dilute with milk/water
- analgesics
- steroids for inflammation
toxicity of toilet bowl cleaner due to:
high acidity
tx of toilet bowl cleaner tox.
- dilute with milk/water
- steroids if stricture possible
- emesis, lavage, act. charc./catharsis CONTRAINDICATED
ammonia/oven cleaner MOA
strong base causes caustic ulceration
tx of ammonia, oven cleaners
dilute with milk/water, steroids
What foods contain Phytoestrogens? Why?**
- beans, lentils, oats, carrots, sesame seeds
- plant defensive mech. to disrupt repro capabilities of their predators
Zearalenone chars.
- type of phytoestrogen
- a mycotoxin/metabolite of Fusarium spp. (grains)
- heat stable and resistant to most mold retardants
- affects most animals (pigs, cattle, sheep)
which animals resistant to zearalenone?
chickens
Zearalenone MOA
estrogen receptor agonist –> “hyperestrogen” syndrome
Symptoms of zearalenone intoxication
GILTS: swelling/edema of vulva, vaginal/rectal prolapse, ovarian atrophy, mammary enlargement
BOARS: testicular atrophy, decreased testosterone
BARROWS: mammary enlargement
SOWS: anestrus, small litters due to abortion, pseudopregnancy, weak piglets
similar symptoms in cattle/sheep
Dx/Tx of Zearalenone
Dx: detect in feed
Tx: change feed; act. charc. or high fiber may reduce elimination due to extensive enterohepatic recycling
