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Cantharidin Poisoning

Other Names: Blister Beetle Toxicity

Cantharidin poisoning is caused by ingestion of blister beetles (Epicauta spp. and Tegrodera latecincta), which contain varying amounts of the toxin canthanridin. Blister beetles are most common in the south central United States. The swarming behavior of blister beetles during mating often result in a large concentration of beetles.

Blister beetles are attracted to alfalfa, and mesquite trees (Prosopis glandulosa) especially the flowers and blossoms. There are thousands of different species of blister beetles.
Each species has differing amounts of cantharidin in their bodies, varying from 1 to 11.3% of their dry weight. Blister beetles are most abundant during the mid-summer months and are attracted to light sources.

Cantharidin is a vesicant and irritant, which initially affects the GI tract following ingestion. Once absorbed, it is eliminated via the kidneys. Elimination results in damage to the kidneys and urinary tract mucosa. The toxin damages the myocardium.


Treatment


Unfortunately, there is no known antidote to cantharidin poisoning. Focus is geared towards reducing toxin absorption and maximizing toxin elimination, replacing fluid losses and correcting electrolyte imbalances, controlling signs of pain, and protecting the GI mucosa.

Clinical Signs

Ataxia
Vomiting beetles
Loss of appetite
Depression
Tachycardia (accelerated heart rate)
Tachypnea (increased respiratory rate)
Sudden death

Diagnosis

  • History
  • Clinical signs
  • Necropsy

Reported Cases

  • Case 1: Cantharidin poisoning in a Bustard A great bustard died by a traumatism, but also presented diarrhoea, congestion of the gastrointestinal tract and kidneys. They had ingested several blister beetles of the species Berberomeloe majalis. The analysis of the stomach content by GC–MS revealed the presence of cantharidin at a concentration of 1.37 g/g of wet weight, a similar level than in other birds poisoned in captivity. Ref

  • Case 2: Cantharidin poisoning in a Chickens Mortality in young chickens was associated with blister beetle consumption. Two species of these insects, Cyaneolytta sp. and Cylindrothorax sp., were found in the chickens' crops, and erosive lesions in the gastrointestinal tract were compatible with blister beetle poisoning (cantharidiasis). Ref

  • Case 3: Cantharidin poisoning in a Emus In 1992, the Texas Veterinary Medical Diagnostic Laboratory received for necropsy several frozen 1-3 month old emu chicks from 1 ranching operation. Insects had swarmed to blooms on mesquite trees (Prosopis glandulosa) near the chick barn, and when a cool front arrived, lights were left on inside to encourage the chicks to seek shelter. As dusk fell, the insects were attracted to the lighted area, and could be seem covering the floor of the barn. Following consumption of the insects, some chicks became ataxic, vomited beetles, became prostate, and died. Others survived following vigorous treatment with oral fluids. At necropsy, the esophagus of each bird was congested and edematous, and the proventricular serosa was hemorrhagic. The gizzard linings were sloughed, the intestinal contents were pink and the livers pale. Ref

Treatment

NameSummary
Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Activated charcoalTo absorb the toxin in the GI tract.
Intravenous fluid therapyTo help correct hypovolemia, provide calcium and magnesium, and to induce diuresis.
NSAIDsFor pain control.

Support

Prevention

Mesquite trees are known to attract blister beetles, therefore don't plant these near your chickens and/or don't allow them to eat the insects from this tree.

Prognosis

Poor

Scientific References

Risk Factors

  • Mesquite trees

Seasonality

WinterSpringSummerAutumn