Musculoskeletal & Pulmonary

Question 1

What are Phenoxyacetic Acid Herbicides?

Answer 1

2,4-D (Scott’s weed and feed), 2,4,5-T, Silvex
Low toxicity in most animals
Dogs most susceptible

Question 2

Mechanism of action of phenoxyacetic acid herbicides?

Answer 2

Unknown

Question 3

Clinical signs of phenoxyacetic acid herbicide toxicosis

Answer 3

GI- vomiting diarrhea, ulceration (often only signs in dogs)

Muscle- reluctance to move, rigid muscles, ataxia, weakness, seizure, rumen atony, MYTONIA with serious toxicosis

Renal tubular degeneration

Hepatic necrosis

Question 4

Diagnosis of phenoxyacetic acid herbicide toxicosis

Answer 4

Oral and GI ulcers
Enteritis, rumen stasis
Congestion of kidney/liver
Hyperemia of lymph nodes
Liver damage
Chemical analysis of serum, urine

Question 5

Treatment of phenoxyacetic acid herbicide toxicosis

Answer 5

GI emesis or lavage
Bathe 
Activated charcoal
Cathartic
Ion trapping

Question 6

What is ergot?

Answer 6

Alkaloid produced in small grains where seeds are replaced by sclerotia (look like mouse droppings)

Question 7

Mechanism of action of ergot toxicity

Answer 7

Dopamine serotonin receptor agonist which produce hallucinations

Leads to decreased prolactin secretion

Cause smooth muscle contraction (uterus and peripheral vasculature which cause abortion and ischemia) -> sever reproductive problems

Question 8

Clinical signs of ergotism (cattle, horses, pigs)

Answer 8

Cattle: Reduced feed intake, weight gain, heat intolerance, retained winter coat (“summer slump”), necrotizing ergotism, fat necrosis, poor reproductive performance

Horses: Abortion, weak foals, prolonged gestation

Pigs: infertility, early parturition, decreased milk production

Question 9

What is necrotizing ergotism?

Answer 9

Lameness, gangrene of extremities, sloughing of feet, ears, and tail during cold weather “Fescue foot”

Question 10

Diagnosis of ergotism

Answer 10

Evidence of sclerotia in feed
Fescue in forage matter
Chemical analysis of feed and forage for ergot metabolites

Question 11

Treatment of ergotism

Answer 11

Remove source, prevent secondary infection

Metoclopromide and domperidone to increase prolactin secretion and normalize gestation

Question 12

What are ionophores?

Answer 12

Compounds that form lipid-soluble complexes with cations and facilitate ion transport across specific membranes

Used as an antibiotic

Used to improve milk production

Question 13

Mechanism of action of ionophore toxicity

Answer 13

Act by increasing intracellular Na+ and Ca++ which leads to mitochondrial swelling and cell death

Usually a result of feed-mixing errors

Horse most sensitive, poultry least sensitive

Question 14

Clinical signs of ionophore toxicity

Answer 14

Horses: anorexia, colic, profuse sweating on flanks, incoordination, weakness

Cattle: same as horses but with diarrhea and respiratory difficulty

Poultry: down with legs and wings stretched out

Dogs: posterior paralysis from lasalocid

Cats: polyneuopathy from salinomycin

Question 15

Diagnosis of ionophore toxicity

Answer 15

Increased muscle enzymes and myoglobinuria
Elevated AST, CK, LDH, ALP, BUN, bilirubin
Decreased K and Ca
Chemical analysis of feed and water (not blood)

Question 16

Treatment of ionophore toxicity

Answer 16

No specific treatment or antidote
FEED CHANGE
Supportive therapy

Question 17

Characteristics of tetanus (clostridium tetani)

Answer 17

Mostly affects cattle

Usually caused by spores in puncture wounds or can be ingested

Question 18

Mechanism of action of tetanus

Answer 18

Toxin acts by blocking release of GABA and glycine (inhibitory transmitters)

Results in overstimulation of muscles leading to stiffness and tetany

Question 19

Clinical signs of tetanus

Answer 19

Stiffness, reluctance to move
Twitching, tremors 
Lockjaw
Unsteady gait with stiff, held out tail
Bloat is common in ruminants 
Later signs include collapse, spasm, death

Question 20

Treatment of tetanus

Answer 20

Antitoxin is available but only useful at very early stages of toxicity
Supportive therapy
Poor prognosis

Question 21

Common respiratory toxins

Answer 21

Ventilatory muscle paralysis:
Botulism, tetanus, snake venom, OP insecticides, strychnine

Respiratory center depression:
Barbiturates, opioids, ethylene glycol, hypnotics, sedatives, tricyclic antidepressants, crude oil