Poisonous snake bite in dogs

Introduction

• Venomonous snakes found through out the world

• world 2500 to 3000 (Species) PAKISTAN 330, land 300 , sea 30 and 29 venomous

• growing population result into humane encroachment to natural habitats

• Deadly encounter with poisonous snake have become more probable

•

The big fourCobra Krait

Russel’s viper Saw-scaled viper

Sheesh Nag, Kala Nag, Karo

Sung Choor

Koriwala

Lundi, Khappra, Sindh khappra, Waziristan khappra, Astola khappra

Poisonous Non poisonous

• Fangs : hollow like hypodermic needles

• Teeth : 2 long fangs

• Tail : compressed

• Short and solid

• Several small teeth

• Not much compressed

Non poisonous snake

Poisonous Snakes

• Neurotoxic – cobra,krait & coral

• Haemotoxic – vipers

• Myotoxic – sea snake

Venom gland

• Snake venom is produced in venom gland

• The fangs are a pair of enlarged teeth containing a channel connected with the venom gland.

•During bite of a prey including human, the venom isinjected subcutaneously or intramuscularly through the venom channel

Snake Venom• Snake venom have special biochemical and

pharmacological properties. They are either colourless or yellowish.

• All snake venoms contain multiple components with different mechanisms of action

• Procoagulant enzymes: (Special for viperidae) That stimulate blood clotting that result in

incoagulable blood. Venoms of such snake as Russelli's viper contain several different

procoagulants, which activate different steps of the clotting cascade

Snake Venom- Cont.• Haemorrhagins that damage the endothelial

lining of blood vessel causing spontaneous systemic haemorrhage.

• Cytolytic or necrotic toxins: • Haemolytic and myolytic phospholipases

A2: These enzymes damage cell membrane, endothelium, skeletal muscles, nerve

and red blood cells.

Snake Venom- cont.• Presynaptic neurotoxins (Typical of

Elapidae and some viperidae): These are phospholipases A2 that damage nerve endings, initially releasing acetylcholine, then interfering with its release

• Postsynaptic neurotoxins (Elapidae): These polypeptide compete with acetylcholine for receptors in the neuromuscular junction and lead to curare- like paralysis.

• Venom of cobra contain predominantly post synaptic neurotoxin and that of Krait contains both Pre and post synaptic neurotoxins

Local signs• fang marks • local pain• local bleeding • bruising• lymphangitis• lymph node enlargement• inflammation (swelling, redness, heat)• blistering • local infection, abscess formation• necrosis

General symtoms (1)

» Nausea, » vomiting,» malaise,» abdominal pain,» weakness, » drowsiness

THE MANAGEMENT OF SNAKE BITES

• Recommended first aid methods:• Immobilize the bitten limb with a splint or sling as

practiced in fracture of long bone.• Ideal is to provide pressure immobilization,

which is especially helpful for venomous cobra and krait bite.

First Aid Methods — Not Recommended

• Traditional tight tourniquets.• Incisions at the site of snake of bite or any other

place.• Local suction either by mouth or by application

of chick.• Application of herbal medicines, stones, seeds,

saliva, potassium permanganate solution.• Ingestion of herbal products like oil, ghee,

pepper to induce vomiting.• Unnecessary delaying.

Management

•Pressure immobilization•Clinical assessment / 20WBCT•ASV•Neostigmine•Supportive therapies ( dilaysis)•Adequate referral

Pressure immobilisation is recommended for bites by neurotoxic elapid snakes, including sea snakes but should not be used for viper bites because of the danger of increasing the local effects of the necrotic venom.

20WBCT(20minutes whole blood clotting test)

• Few ml of fresh venous blood placed in a NEW, CLEAN, DRY, GLASS test tube

• Left undisturbed for 20mn• Gently tilted to 45° and examined• If it has remained liquid: consumption

coagulopathy ASV required• Clotted: ASV not necessary (at this stage)

Treatment of adverse raction

• Usually within 20mn from start of ASV• Drug of choice = Adrenaline, 0.5 mg IM, to

be repeated if symptoms donot improve within 15mn

• 100 mg hydrocortisone + 25 mg Promethazine IM / 10 mg chlorphenimarine IV

Types of ASV available

• Liquid ASV (NIH)• Lyophilized (imported from India)• Liquid ASV requires no reconstitution but

of cold chain• Lyophylized ASV no refrigeration needed

but 1h required for reconstitution with distilled water

Dose of ASV (1)

• Depending on the amount of venom injected by the snake

• Cobra and Russel’s viper 60mg • Krait inject less venom but neurological

symptoms similar to Cobra • Each ASV vial neutralizes 6mg of Cobra

and Russel’s viper venom• Initial dose 8-10 vials (NIH/indian ASV

same neutalzing capacity)

Dose of ASV (2)• Saw scaled viper (Echis carnatus, smaller, found

in India) bite around 15 mg of venom• Larger saw scaled viper (Echis sochureki) found

in Pakistan: no studies

Administration

• Over 1 hour maximum• IV injection or continuous infusion• SC, IM, around bite site : no

Neostigmine

• Cobra venom is a post synaptic neurotoxin and blocks the nicotinic receptor causing acetylcholine to be unable to bind

• Neostigmine prolongs the life of acetylcholine by inhibiting cholinesterase, increasing the likelywood of acetylcholine binding with unblocked receptor

• 1.5 mg neostigmine methylsulfate + 0.6 mg Atropine• Repeat the tests• If objective improvement, repeat neostigmine + atropin

every 30mn

Prevention (1)• Education ! Know your local snakes, know the

sort of places where they like to live and hide, know at what times of year, at what times of day/night or in what kinds of weather they are most likely to be active.

• Be specially vigilant about snake bites after rains, during flooding, at harvest time and at night.

Thank You !