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Transcript of Animals
Howell Foster PharmD
The toxicology surrounding creatures found in Arkansas and other parts of the world is often wrong and filled with myth.
Very common in Arkansas
Painful bite with mild venom
Not considered "harmful" to man
Numerous coarse hairs on the body
Used as a defense mechanism
Black Widow (Latrodectus mactans)
Actually very common
Prefer dark areas and are timid
Typically jet black with reddish hour glass on the abdomen.
However color and pattern can vary
Black Widow Venom
At least six bioactive proteins
Small amt of proteolytic enzyme
Polypeptide consisting of approximately 1000 amino acids
Massive acetylcholine/NE release in the neuromuscular junction followed by depletion
Brown Recluse (Loxosceles reclusa)
Very common in Arkansas
Often found in homes, wood piles, leaf litter etc
Not web based
Violin shaped markings on the cephalothorax
Treatment black widow bites
Toxicity: Brown Recluse
Composed of a number of proteins, enzymes, and nonenzymatic polypeptides.
One of the proteins posses sphingomyelinase activity.
Currently, these mechanisms appear to be molecularly complex and may be dependent on many different toxins.
DERMAL NECROSIS/SYSTEMIC EFFECTS
Polymorphonuclear leukocytes also appear to play a role in the development of cutaneous loxoscelism (i.e., skin necrosis). Loxosceles venom has been shown to be a potent inducer of multiple inflammatory mediating chemokines in endothelial cell cultures.
Venom toxins may act as proteases upon fibrinogen and basement membrane constituents. Its postulated that all of these degrading activities are responsible for producing hemorrhage, delayed wound healing and renal failure. By disrupting the subendothelial basement membrane, blood vessel wall instability and increased permeability can occur.
Renal damage as well as increased serum urea concentrations without causing hemolysis has been seen in the mouse model. Researchers were able to identify a 30 kiloDalton toxin that bound to renal tissue in venom treated mice.
Monitoring/Treatment: Brown Recluse
CBC for evidence of hemolysis in patients with systemic symptoms. In severe envenomations follow platelet count, INR or PT, PTT, urinalysis, urine output, and renal function tests.
Type and crossmatch carefully in patients with evidence of hemolysis.
CPK in patients with systemic symptoms. Rhabdomyolysis has been reported following severe envenomation. Monitor LDH and serum potassium in patients with hemolysis.
The wound should be cleaned with soap and water. There is no local treatment which prevents or reduces systemic toxicity.
Parenteral opioids and antivenom remain the most effective therapy for severe Latrodectus envenomation.
SKELETAL MUSCLE RELAXANT
Muscle relaxants such as diazepam or methocarbamol may help relieve muscle spasm
ANTIVENIN (LATRODECTUS MACTANS)
Antivenin is indicated in the presence of serious systemic signs, in high-risk patients, and in patients whose pain is not adequately controlled by parenteral opioids and muscle relaxants.
Consider in high risk patients (age less than 5 years or greater than 60 years, respiratory difficulty, marked hypertension, pregnancy, patient distress not responding to other measures.
"There is no proven therapy with efficacy for loxoscelism, local wound care and first aid may be the most appropriate conservative therapy."
WOUND CARE: Most bites require little more than local care including thorough cleansing. Most wounds can then be treated with rest, ice, elevation and compression (RICE).
PRURITUS : Diphenhydramine 5 mg/kg/day orally, with a maximum dose of 25 to 50 mg 4 times a day. Hydroxyzine may also be used as follows: Adults: 25 to 50 mg every 6 to 8 hours; maximum dose 400 mg/day.
INFECTION: Antibiotics are indicated for confirmed infection, usually from Staphylococcus.
PAIN: For mild pain relief nonnarcotic analgesics are indicated. For moderate or severe pain narcotic analgesics may be given. Short term ice over the lesion may be effective.
SYSTEMIC ENVENOMATION: Systemic loxoscelism may develop in mild or severe cases; it is most likely to occur in children. Treatment for systemic effects includes hydration, serial monitoring of CBC, electrolytes, urinalysis for severe cases. Ensure adequate urine output in patients with hemolysis. Transfusion may be necessary in patients with severe hemolysis.
ANTIVENOM: Commercial antivenom is not available in the United States.
A variety of drugs and procedures have been advocated to reduce the extent of tissue necrosis, but none have been proven effective in controlled trials.
DAPSONE: It was presumed that by limiting both leukocyte migration and subsequent leukocyte degranulation and cytokine discharge at the site of envenomation, the microtubular inhibitors could limit the degree of tissue damage. COMPLICATIONS: Dapsone may cause hemolysis, which is also a complication of Loxosceles envenomation. The risk of hemolysis is greater in patients with G6PD deficiency. Dapsone may also cause severe methemoglobinemia.
CORTICOSTEROIDS: Systemic steroids have been used to prevent kidney failure and stop hemolysis. However, efficacy of steroid use has not been determined.
COLCHICINE : A leukocyte microtubular inhibitor; however, the effectiveness of this agent has NOT been supported in controlled drug trials and use may produce toxicity.
NITROGLYCERIN : There has been some anecdotal evidence that topical nitroglycerin may be effective to treat dermonecrotic lesions, but the research to date has been inconclusive. Its use is NOT recommended.
CURETTAGE: Early curettage to remove the subcutaneous tissue in the necrotic area of the lesion has also been advocated, but has not been well studied.
WOUND EXCISION: Early wound excision was once widely advocated,but more recent evidence suggests that early excision may increase the rate of complications and extend the dermonecrosis. Excision is only suggested in patients with a large lesion that has progressed over 6 to 8 weeks.
HYPERBARIC OXYGEN: Has been suggested for the treatment of rapidly progressing or cosmetically significant bites. Its effectiveness has not been proven in controlled trials. The findings have been inconclusive and the treatment cannot be recommended.
Common in Arkansas
Our species have only a mild venom
Sting is very painful
Treatment is directed at signs/symptoms
Scorpions (Arkansas Only)
US species mild venom
Like warm moist environment
Centipedes (Arkansas Only)
True Bug (Hemiptera)
Injects digestive enzymes directly into prey
Tx sxs (pain, itching and erythema)
Rarely Chagas Disease in the US
Assassin Bug (Triatoma sp)
Includes Bees, Wasp, Yellow Jackets, Hornets, and Ants
Possess a stinging apparatus
Wound typically has marked symptoms
Fatalities can occur in sensitive individuals
Good wound care
Antihistamines and analgesics
Dilute alkaline solutions (NaHCO3 or 2-3% ammonia)
Epi-Pen for sensitive individuals
Catfish stings or “finned”
Topical fish may be encountered
Rinse area well
Immerse in hot water (<113F)
Analgesic, ABX prn
Commonly found amphibian
Large glands behind the eyes secrete a milky substance
Newts and Salamanders
Found in lakes, streams, caves, and moist areas
Poisoning is from its secretions
Lizard found in the SW United States
More agile than it appears
Venom is located in the saliva