Poison, Parasites, and Toxicology Notes

Poison & Parasites

• Ear Mite
• DANGER
• POISON
• Flea Eggs
• Flea Larva
• Tapeworm
• Adult Flea
• Tick
• Sarcoptes Mange
• Heartworm

Introduction to Toxic Agents and Toxicity

• Poison: Any substance (natural or synthetic) that can destroy life or injure health upon introduction to a living organism.
• Toxin: Poisonous compounds of biologic origin, synthesized by animals, plants, or organisms.
• Toxicity: Refers to the amount of a toxic agent necessary to cause a detrimental effect.
• Toxicosis: A pathological condition caused by the action of a poison or toxin.

Toxicology

• Definition: Study of adverse effects of chemical substances on living organisms.
• ADME Concept:
  • Absorption: How a toxic agent enters the body.
  • Distribution: How the agent spreads through the body.
  • Metabolism: How the body transforms the agent.
  • Excretion: How the body eliminates the agent.

Factors Affecting Toxicity in Animals

• Dose-dependant: The biological effect often depends on the dose administered.
• Route of exposure: Ingestion, inhalation, or dermal contact can affect toxicity.
• Duration and frequency of exposure: Longer or more frequent exposure increases risk of toxicity.
• Modes of action:
  • Systemic: Effects are spread throughout the body.
  • Organ Toxicants: Effects are localized to specific organs.
• Environmental factors can influence consumption rates and occurrence of toxic agents.

Biologic Factors Affecting Toxicity in Animals

• Selective toxicity: Certain species may be more susceptible based on genetics.
• Age and size: Younger or smaller animals may be more vulnerable.
• Nutritional and dietary factors: Nutritional status can affect toxin metabolism.

Principles of Therapy for Toxicosis

• Three Basic Principles:
  1. Prevention of further absorption: Washing, emesis, gastric lavage, laxatives, activated charcoal.
  2. Supportive/symptomatic treatment: Managing symptoms like seizures, breathing issues, shock, heart problems.
  3. Specific antidotes: Depending on the toxin involved.

Cyanogenic Plants

• Hydrogen Cyanide (HCN): Highly poisonous, blocks cellular respiration.
  • Found in cyanogenic glucosides that release HCN when plant tissue is damaged.
• Mechanism of action: HCN prevents body cells from receiving oxygen, leading to cellular asphyxiation.
• Water accelerates release of HCN, causing acute poisoning and death.
• Affected animals may exhibit cherry red blood prior to death, indicative of cyanide poisoning.
• Chronic Effects: Prolonged exposure to sublethal doses may cause nerve function loss.

Common Cyanogenic Plants

• Includes:
  • Lily of the Valley
  • Maleberry
  • Marijuana
  • Milkweed
  • Nightshade
  • Oleander
  • Rhododendron
  • Wild Black Cherry
  • Others listed in transcript.

Cocklebur (Xanthium spp.)

• Toxic principle: Glycoside carboxyatractyloside (CAT).
• Target organ: Liver, causes acute and severe necrosis.
• Signs of poisoning: Depression, weakness, unusual gait, convulsions, and potentially death.
• Ingestion effects: As little as 0.75% of body weight can be lethal, symptoms appear hours after ingestion.

Loco Weed (Astragalus and Oxytropis spp.)

• Most widespread poisonous plant: Affects horses, cattle, sheep, and goats.
• Toxin: Swainsonine, which causes oligosaccharide accumulation leading to cellular dysfunction.
• Effects: Neurological damage, emaciation, reproductive dysfunction, congestive heart failure.

Castor Bean (Ricinus communis)

• Contains ricin: Highly toxic to all animals, inhibits ribosomal protein synthesis.
• Signs of poisoning: Loss of appetite, weakness, colic, CNS depression, and possibly bloody diarrhea.
• Treatment: Inducing vomiting or admin of activated charcoal if ingestion occurs.

Parasites

• Definition: Organisms living on or inside another living organism (host), obtaining benefit at the host's expense.
• Types:
  • Ectoparasites: Live outside the host (e.g., ticks, fleas).
  • Endoparasites: Live inside the host (e.g., roundworms, tapeworms).
• Anthelmintic: Chemical used to control parasitic infections.

Common Ectoparasites

• Flies: Blood-sucking; can transmit diseases.
• Lice: Wingless, cause itching and hair loss.
• Mites: Cause mange; tunnel into skin.
• Mosquitoes: Transmit diseases like West Nile virus.
• Ticks: Blood-feeding and disease vectors.

Common Endoparasites

Horses

• Includes large and small strongyles, roundworms, and bot flies.

Cattle

• Affected by roundworms, tapeworms, lungworms, and coccidia.

Sheep/Goats

• Notable for barber pole worm; affects health and productivity.

Pigs

• Large roundworms cause significant health issues.

Chickens

• Various roundworms impacting egg production and overall health.

Fasciola hepatica (Common Liver Fluke)

• Causes fascioliasis in ruminants, acquired from contaminated water plants.
• Symptoms: Abdominal pain, anemia, sudden death with acute disease; chronic infection may show subtle signs.
• Diagnosis & Management: Fecal tests and antibody tests for diagnosis; treatment and prevention are possible.

Parasite Management

• Maintain cleanliness in environments to reduce parasite load.
• Use feeding practices that limit ground contamination.
• Provide a balanced diet to promote health.
• Rotate pastures and check livestock regularly for infestations.