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57 Cards in this Set
- Front
- Back
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What are some sources of lead?
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Paint, tires, batteries, lubricants, exhaust, news print, glazed pottery, linoleum, roofing, pesticides, herbicides
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What are the 3 toxic actions of lead?
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1) binds to sulfhydryl groups, interferes w/ enzymes
2) Interferes w/ ALA dehydrogenase activity -Impaired heme synthesis 3) Neurologic |
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What are 5 ways that lead causes neurologic damage?
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1) Capillary damage
2) Demyelination 3) Interferes w/ GABA 4) Interferes w/ dopamine 5) Interferes w/ Ca movement |
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What is the toxic dose of lead in calves? Cattle?
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Calves: 200-600 mg/kg
Cows: 600-800 mg/kg |
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What is the toxic dose of lead in goats? horses?
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Goats: 400 mg/kg
Horses: varies w/ time of exposure in chronic cases |
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Describe the absorption of lead.
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Slow and incomplete
-2-10% |
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How is lead transported in serum?
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As proteinate
-60-90% in erythrocytes once absorbed |
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Where is lead deposited?
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Bone
-After temporarily in soft tissue |
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How is lead excreted?
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Slowly in bile
-Little urine in chronic cases unless chelated |
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Why do cattle tend to get lead poisoning?
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Cattle are curious and chew on everything & swallow w/o chewing
-Lack of salt makes them lick more |
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What are 7 acute signs of lead poisoning in cattle?
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1) Twitching muscles
2) Hyperesthesia 3) Head pressing 4) Blindness 5) Ataxia, circling, stumbling 6) Odontoprisis 7) Seizures |
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What are the 3 major DDX for acute lead toxicity in cattle?
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1) Brain abscess
2) Polioencephalomalacia 3) Hepatic encephalopathy -Could also be T.E.M.E, organochlorine intoxication, rabies |
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What are the 3 circumstances of lead chronic lead poisoning in horses?
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1) Usually in soil & accumulates in forage
2) Lead in soil -near smelters -Lead mines -battery recycling plants -Near highways when leaded gasoline used 3) Consumed over a period of time |
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**What sign of chronic lead toxicity is less common in horses?
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Cerebral signs less common in horse
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What are the 9 signs of chronic lead toxicity in horses?
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1) Laryngeal paralysis
2) Dysphagia 3) Ataxia 4) Weight loss 5) Hyperesthesia, tremors 6) Lack of anal tone 7) Blindness 8) Cerebral signs less |
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What are 5 DDX for laryngeal hemiplegia caused by chronic lead toxicity in horses?
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1) Guttural pouch disease
2) Retropharyngeal abscess 3) Nutritional myopathy 4) Temperohyoid fracture 5) Botulism |
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What are 3 DDX for chronic lead toxicity in horses?
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1) Hepatic encephalopathy
2) EPM 3) Many other neuro diseases |
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What will you see on a CBC of animals with lead poisoning?
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-Inconsistent
-May have anemia, erythrocyte alterations, howell-jolly bodies -Basophilic stippling -**Seen less in Large animal |
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What can you do to test levels of lead in the blood if you think the lead has already began to store in the bone?
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Chelate with Ca EDTA
-Use heparin tubes, EDTA chelates lead & calcium |
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If you are dealing with a chronic case of lead toxicity, what abnormalities can be detected?
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1) Blood porphyrins increase (IV fluorescence)
2) Urine ALA increased |
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What are the gross lesions of lead poisoning upon post mortem examination?
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Minimal specific lesions
-Brain swelling, congestion -Pale liver & muscles |
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What can be seen histologically in an animal with lead toxicity?
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Laminar cortical necrosis
Renal tubular necrosis |
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What organs do you want to test for lead levels?
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Liver or kidney
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What can you do to treat lead toxicity?
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1) Chelate lead
-Ca disodium EDTA -DMSA 2) Ca-EDTA (not commercially available) 3) Thiamine may reduce clinical signs but not increase survivability 4) Control seziures 5) Supportive care -Fluid, nutrition 6) Remove lead in GI tract -MgSO4 or rumenotomy |
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Why do you have to use caution when using calcium disodium EDTA to treat lead poisoning?
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May increase blood levels and cause more damage
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What are 2 ways to prevent lead poisoning?
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1) Remove source
2) If topsoil Pb> 175 ppm don't feed forage |
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How do puppies get exposed to lead?
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Chew on painted areas w/ lead or ingest lead objects i.e. drapery weight, fishing sinkers
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How do cats get exposed to lead?
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Licking paws w/ lead contaminated dust from remodeling projects
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True or false. Acute death from lead toxicity is commonly seen in small animals.
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False, not common
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**What is the most common type of clinical signs seen in small animals with lead poisoning?
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Gastrointestinal
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What are 5 GI signs seen in small animals with lead toxicity?
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1) Anorexia
2) Depression 3) Mild abdominal pain 4) Vomiting/ diarrhea 5) Pica appetite |
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What are 2 neurological signs of lead toxicosis in small animals?
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1) Hyperexcitability/ hysterical or depression
2) Intermittent seizures |
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Why is lead poisoning in waterfowl and other birds often non-specific?
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Bc disease is often chronic in nature, occurs rapidly
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What usually kills waterfowl/birds with lead poisoning?
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Infectious processes e.g. aspergillus
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What are 5 ways to diagnose lead poisoning?
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1) History of potential exposure
2) Appropriate clinical signs: unexplained GI & NS, clin path unreliable 3) Radiograph: find source- can't rule out w/ radiographs 4) Histopathology- may see nice lesions in brain 5) chemical analysis |
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**Why shouldn't you base lead poisoning treatment on clinical signs?
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Whole blood levels do not correlate w/ clinical signs
-Elevated levels are diagnostic |
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What are some areas in the body you can measure lead levels in for diagnosis of toxicity?
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Liver & kidney***
Feces Urine, hair |
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What are the 2 major things seen on clinical pathology of lead poisoning?
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1) nRBCs w/o significant anemia
-Abnormal bone marrow release of nucleated cells due to effect on spaces of sinusoidal barrier 2) Basophilic stippling -not consistent and reliable in cats!!!~~ |
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What can you see on radiographs that is indicative of lead poisoning?
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Radiopaque material
Metaphyseal sclerosis Birds: hypochromic, regenerative anemia |
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Why aren't the gross lesions of lead poisoning very helpful?
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Often absent or nonspecific
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What are 6 ways to treat lead toxicity?
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1) Decontaminate
2) Chelation 3) Thiamine hydrochloride (vit B1) 4) Seizure control 5) Zinc supplementation 6) supportive |
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What are 5 ways to decontaminate a patient w/ lead toxicity?
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1) emetics
2) lavage 3) Cathartics -Mg or NaSO4- binds Pb 4) Surgery -essential to remove source 5) Birds- peanut butter and metamucil provides bulk and lubrication |
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What is lead chelation?
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Exchanges calcium for lead in blood, tissues and bone and enhances urinary excretion
-**They are not necessarily mutually exlcusive |
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What are 4 agents that can be used to chelate lead?
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1) Ca EDTA
2) Succimer 3) Dimercaprol 4) Penicillamine |
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What are the side effects of Ca EDTA?
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Renal tubule necrosis and transient bone marrow suppression
-24-48 h increased dumping into urine |
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What should you add to Ca EDTA when giving to cats or dogs?
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Dilute and add to lidocaine to ease the pain
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**What is the chelation drug of choice?
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Succimer
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Why do we like succimer for a chelating agent?
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No enhance lead GI absorption
-So don't need to remove source from gut first like w/ CaEDTA |
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What are the disadvantages of using dimercaprol for lead chelation?
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Very painful, nephrotoxic
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How does dimercaprol work?
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Enhances urinary and bile lead excretion
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**When do we use penicillamine for lead chelation?
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Mild intoxications or follow-up for in patient treatment
-Also used in Cu toxicity |
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*How is penicillamine adminsitered?
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Per os
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What is the disadvantage of penicillamine for a lead chelating agent?
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May exacerbate clinical signs due to redistribution
-If allergic to penicillin may also be allergic to penicillamine |
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Treating lead toxicity should include ______ supplementation.
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Zinc
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What are 6 things that can be done for supportive care of lead toxicity?
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1) Dexamethasone
2) Antibiotics 3) fluids 4) Caloric intake 5) Vit A, D, B complex 6) Calcium gluconate/lactate |
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What is the prognosis of an animal with blood lead levels < 1.0 ppm?
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Good
-Should see dramatic improvement in 24-48 h |
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When is lead toxicity a bad prognosis?
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> 1.0
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