Lead

Question 1

What is the most common poisoning of livestock?

Answer 1

lead

- but it affects all species

Question 2

what is the cause of the biochemical or subcellular effects of lead?

Answer 2

affinity of lead for SH (sulfhydryl) or imidazole groups

Question 3

The binding of lead to various macromolecules impair which functions?

Answer 3

enzymes - substrate
mitochondria - decrease ATP
reproduction - chromosomal damage
immune system - immunosuppression

Question 4

In which organ systems are the cellular and clinical affects most aparent?

Answer 4

GI
nervous
hemopoetic

Question 5

What are the GI effects of lead?

Answer 5

irritation, gastroenteritis, rumestasis in cattle

diarrhea/constipation

Question 6

What are the nervous effects?

Answer 6

encephalopathy
- capillary damage causes hemorrhage and congestion in the brain followed by edema and malacia
blindness and peripheral nerve degeneration
no direct harm to brain
affects vascular supply –> edema and swelling

Question 7

What are the hemopoetic effects?

Answer 7

anemia
reduced iron uptake
RBC fragility
heme synthesis altered
by enzymes containing SH

Question 8

What are the effects on the kidey?

Answer 8

degenerative changes

• tubular necrosis, nephritis, fibrosis and yaline degen
• acid fast inclusions bodies are present

Question 9

What are the effects on the liver?

Answer 9

mild degen

little clin significance

Question 10

What are the MSK effects?

Answer 10

osteoporosis

- common in sheep

Question 11

What are the affects on the resp system?

Answer 11

impaired neuro = impaired swallowing mech and cause aspiration pneumonia

Question 12

What are the acute and subacute syndromes characterized by? two general systems?

Answer 12

GI and neuro

Question 13

How long does the acute syndrome last? which age?

Answer 13

lasts 24h
usually younger animals
one or two in herd

Question 14

What are the clinical signs of acute poisoning?

Answer 14

behaviour
- mania, frenzy, charging fences, bellowing, head pressing

locomotor
- staggering an muscle tremors

nervous phenomena

• champing jaws, blindess, snapping eyelids
• hyperesthesia
• intermittent tonic-clonic convulsions
• opisthotonus

GIT

• frothing, salivation (impaired swallowing
• rumen stasis
• abdominal pain
• abnormal eructation

Question 15

How long does the subacute poisoning last? which age?

Answer 15

adults typically 3-4d

Question 16

What are the clinical signs of subacute poisoning?

Answer 16

behavioural

• dullness
• head pressing

locomotor

• abnormal gait
• incoordination, muscle tremors, staggering, often stand immobile, occasionally circle

nervous
- blind, depression, hyperesthesia, head bobbing, convulsions absent

GIT
– grinding teeth, rumen stasis, salivation, anorexia, diarrhea/constipation, abdominal pain

Question 17

What is the main difference between subacute and acute?

Answer 17

lasts longer and no convulsions with subacute

Question 18

What are signs/type is specific to sheep?

Answer 18

osteoporosis

usually subacute

Question 19

What type and signs are specific to horses?

Answer 19

chronic

• colic, pharyngeal paralysis (roaring)
• aspiration pneumonia
• no convulsions

Question 20

What type and signs are specific to pigs?

Answer 20

primarily GIT - vomiting

few CNS signs

Question 21

what type and signs are specific to dogs/cats?

Answer 21

similar to pigs

• vomiting
• hyperexcitability
• convulsions
• altered hysterical bark

Question 22

What are some sources of lead?

Answer 22

paint, oil, lubricants, lead toys, lead shot, batteries, used crankcase, old shingles, industrial contam

Question 23

What is the absorption and distribution?

Answer 23

higher absorption in young animal

cumulative
half life is many month
enters blood distributes rapidly to liver and kidney (1d)
displace Ca
does not accumulate in brain

gut>blood>kidney>liver>bones

Question 24

What Vitamin from sun can increase absorption?

Answer 24

Vit D

Question 25

What is the excretion?

Answer 25

kidney

milk - minor

Question 26

Why are young animal more susceptable?

Answer 26

low iron milk diet

iron competes with lead

Question 27

What can be submitted antemortem to confirm Dx?

Answer 27

heparinized blood (WHOLEBLOOD) in RBC
rumen contents
fecal contents

Question 28

What can be submitted postmortem?

Answer 28

liver and kidney (best)
rumen, fecal (variable)
brain (poor)

Question 29

What is detected on clin path?

Answer 29

anemia
basophilic stippling
increased ESR
anisocytosis
hypochromia
leptocytes
altered enzymatic activity

kidney damage
- proteinuria, glucouria

Question 30

What else can be seen diagnostically?

Answer 30

increased radiographic density
growth plates in bone
stomach or rumen contents

Question 31

What is the treatment for food animals?

Answer 31

discouraged

• food safety
• prognosis
• potential repro problems

Question 32

What are some treatment chelation therapys?

Answer 32

penicillamine (oral)
british antiLewistie IV
- short acting, lipid soluble
- penetrate CNS
Calcium EDTA (IV)
- no longer approved for livestock
succimer (oral)
- best for dogs but hard to get

Question 33

What other treatment options are there for lead?

Answer 33

thiamin (IV)
- chelates and cheap
MgSO4 (oral)
- acts as laxative and binds lead
sedation
rumen lavage
rumenotomy
zinc supplementation
rumen transplant

Question 34

What is the best treatment?

Answer 34

calcium EDTA + thiamin (IV)

Question 35

What is used for supportive therapy?

Answer 35

force feeding
oral fluids
mannitol (helps reduce swelling in the brain)
edema

Question 36

What is the epidemiology of lead?

Answer 36

young animals in season when batteries are changed (harvesting)
- may and august

Question 37

what is the economic implications of lead?

Answer 37

expensive in cattle 
meat and milk residues
lack of approved medications 
reportable disease in alberta
- must cull