Vet' Medicine

Introduction

Mycotoxicosis refers to poisoning caused by toxic compounds (mycotoxins) produced by certain fungi and molds growing on feed, grains, hay, silage, or stored agricultural products. These toxins can affect a wide range of animal species and are responsible for significant economic losses in livestock production worldwide.

Common and clinically important mycotoxins in veterinary medicine include aflatoxins, ochratoxins, and ergot alkaloids. The severity of disease depends on the type of toxin, concentration, duration of exposure, nutritional status, and species susceptibility.

General Causes and Risk Factors

Common Sources of Mycotoxins

• Moldy grains and feed
• Poorly stored hay or silage
• Warm and humid storage conditions
• Water-damaged feed ingredients
• Contaminated pasture grasses

Predisposing Factors

• Improper feed storage
• High environmental humidity
• Poor ventilation in storage facilities
• Extended storage periods
• Nutritional deficiencies or stress in animals

General Pathophysiology of Mycotoxicosis

• Mycotoxins are absorbed through the gastrointestinal tract
• Toxins interfere with cellular metabolism and enzyme systems
• Major target organs include the liver, kidneys, nervous system, and blood vessels
• Some toxins suppress immune function or impair reproduction

Clinical disease may be acute or chronic depending on toxin dose and duration of exposure.

Aflatoxicosis (Aflatoxin Poisoning)

Overview

Aflatoxins are produced mainly by Aspergillus species and are among the most important mycotoxins affecting livestock and poultry. They primarily cause liver damage and immunosuppression.

Common Sources

• Moldy corn and grains
• Peanuts and oilseed meals
• Poorly stored feed ingredients

Species Affected

• Poultry (highly susceptible)
• Pigs
• Cattle
• Dogs

Pathophysiology

• Toxin absorption from the gastrointestinal tract
• Metabolism in the liver into reactive compounds
• Severe liver cell injury and impaired protein synthesis
• Reduced immune function and clotting abnormalities

Clinical Signs

• Reduced feed intake
• Poor growth and weight loss
• Depression and weakness
• Jaundice
• Reduced egg or milk production
• Bleeding tendencies in severe cases

Diagnosis

• History of moldy feed exposure
• Liver dysfunction on blood tests
• Feed analysis for aflatoxin levels
• Postmortem evidence of enlarged or pale liver

Treatment and Control

• Immediate removal of contaminated feed
• Supportive nutritional therapy
• Use of toxin binders in feed where appropriate
• Improved feed storage conditions

Ochratoxicosis (Ochratoxin Poisoning)

Overview

Ochratoxins are fungal toxins primarily affecting the kidneys. They are produced by several species of Aspergillus and Penicillium.

Common Sources

• Moldy cereal grains
• Stored feed contaminated by fungi
• Poor-quality feed ingredients

Species Affected

• Pigs (particularly susceptible)
• Poultry
• Dogs

Pathophysiology

• Toxin accumulation in kidney tissues
• Damage to renal tubules
• Impaired kidney filtration and function
• Possible immunosuppressive effects

Clinical Signs

• Excessive thirst and urination
• Poor growth and weight loss
• Weakness and dehydration
• Kidney failure in severe cases

Diagnosis

• History of mold exposure
• Evidence of kidney dysfunction
• Feed testing for ochratoxins
• Postmortem kidney lesions

Treatment and Control

• Removal of contaminated feed
• Supportive fluid therapy
• Monitoring kidney function
• Proper storage and drying of feed

Ergotism (Ergot Alkaloid Poisoning)

Overview

Ergot alkaloids are toxins produced by fungi such as Claviceps species that infect cereal grains and grasses. These toxins primarily affect blood vessels and the nervous system.

Common Sources

• Ergot-contaminated rye and cereal grains
• Infected pasture grasses
• Contaminated hay or silage

Pathophysiology

• Constriction of blood vessels (vasoconstriction)
• Reduced blood supply to extremities
• Nervous system stimulation or depression
• Reduced prolactin secretion and reproductive effects

Clinical Signs

Gangrenous Form

• Lameness
• Cold extremities
• Necrosis of ears, tail, or hooves
• Sloughing of affected tissues

Nervous Form

• Tremors
• Excitement or convulsions
• Incoordination

Reproductive Effects

• Reduced milk production
• Poor reproductive performance
• Agalactia in lactating animals

Diagnosis

• History of contaminated grain or pasture exposure
• Identification of ergot bodies in feed
• Clinical evidence of gangrene or neurological disease

Treatment and Control

• Removal from contaminated feed or pasture
• Supportive therapy
• Protection of affected tissues from further injury
• Proper grain cleaning and pasture management

General Diagnosis of Mycotoxicosis

• Detailed feed history
• Inspection for mold contamination
• Laboratory testing of feed samples
• Blood chemistry and organ function testing
• Postmortem examination where necessary

General Prevention and Control

• Proper drying and storage of feed
• Regular inspection of feed for mold growth
• Maintaining low moisture levels in storage facilities
• Use of mold inhibitors or toxin binders where appropriate
• Discarding visibly moldy feed

Economic and Clinical Importance

Mycotoxicosis is a major cause of production losses and health problems in livestock industries worldwide.

• Reduced growth and feed efficiency
• Immunosuppression and increased disease susceptibility
• Reproductive losses
• Reduced milk, meat, and egg production
• Feed wastage and economic losses

Effective feed management and storage practices are essential for preventing mycotoxin contamination and protecting animal health.