Toxicology and wound management

A thorough medical history is essential to

approaching emergency treatment of toxicosis

Toxicology

The study of the adverse effects of chemicals and other types of exposures on living organisms and the environment

Toxins

Natural toxic substances produced by plants, animals, and microorganisms (such as snake venom and bacterial toxins)

Most common routes of toxicant exposure

Ocular, dermal, and ingestion

When dyspnea or cyanosis is present

Artificial respiration should be provided for the animal

Decontamination

Is crucial to prevent toxicant absorption and is guided by the animals history, clinical signs, and time frame

If dermal exposure happens

They should be washed using mild liquid dishwashing detergent and water

If ocular exposure happens

The eyes are repeatedly flushed with lukewarm water or saline for 30 minutes

If external exposures happen

Induction of emesis (vomiting) should be done with caution and it isn’t performed on rodents, rabbits, birds, horses, and ruminants

Animals that aren’t candidates for emesis induction

• Animals with current or previous cardiovascular disease

• Animals with poorly controlled epilepsy

• Severely debilitated or weak animals

• Animals that have had recent abdominal surgery

• Hyperactive animals

• Depressed or comatose animals

Emesis shouldn’t be induced for

Toxicants that are corrosive because vomiting these substances will re-traumatize the esophagus

In the case of corrosive substances

the stomach contents should be diluted with water or milk, and GI protectants should be administered

Activated charcoal

Is an adsorbent, meaning it attracts substances to its surface

Dose for activated charcoal

1 to 2 g per kg of body weight

What chemicals don’t absorb to activated charcoal?

alcohols, petroleum distillates, heavy metals, iodides, NaCl, chlorate, floride, and fertilizer

Cathratics

Purgatives and decrease GI transit time, are used to enhance the elimination of the activated charcoal and absorbed toxicant complex

What is gastric lavage?

this entails emptying the toxicant-containing stomach contents

What is an enterogastric lavage?

It’s essentially a gastric lavage followed by an enema, and also called a through and through lavage

Mycotoxins

Found in moldy food can cause tremors and seizures in animals

Theobromine and methylxanthines (caffeine)

They’re found in chocolate and are toxic to dogs and cats

Methylxanthines can cause

polyuria, polydipsia, vomiting, diarrhea, hyperactivity, increased HR, tremors, and even death

Onions and other members of the allium family (garlics and leeks) can cause

Red blood cell damage (hemolytic anemia) in dogs, cats, cattle, and horses

The main toxic principle in onions

n-propyl disulfide

Ingestion of macadamia nuts by dogs

They may experience tremors, hyperthermia, ataxia, vomiting, depression, and weakness

The dough rising process in bread dough causes

Intoxication and bloating that can be limited by administering cold water or ice cubes (by mouth or stomach tube)

Grapes and rasins and cause

Kidney failure in dogs

Xylitol

A sugar substitute found in human foods and dental products

Xylitol toxicosis

Induces insulin release in dogs, causing hypoglycemia, weakness, ataxia, vomiting, and depression

Common toxic acids

• hydrochloric acid

• sulfuric acid

• nitric acid

• phosphoric acid

• oxalic acid

• sodium bisulfate

Household cleaning agents and items that are toxic for small animals

• alkalis

• bleaches

• detergents: anionic and nonionic

• detergents: cationic

• zinc

• lead

• nicotine

• glowing jewelry

Alkalis

Found in drain openers, oven cleaners, hair relaxers, and electric dishwashing liquids; they cause direct tissue damage. Are treated in the same manner as acids

Bleaches

Are mucosal irritants, and exposure is treated by bathing the animal and diluting the bleach

Detergents: Anionic and Nonionic

These types can be toxic to pets when ingested and can cause ocular and skin irritation

Detergents: Cationic

These can cause systemic and local toxicity, and causes lesions that are similar to those caused by acids and alkalis and are treated as such

Zinc

Is contained in metal implements (wires and screws) and coins. It’s absorption can cause hemolytic anemia, renal failure, and possibly death

Lead

Found in building and automotive materials causes GI, CNS, and blood toxicity

Nicotine

Ingestion from tobacco products can cause tachycardia, excitation, and other symptoms due to the cholinergic effects; later, brachycardia and respiratory paralysis can ensue

The toxic principle in glowing jewelry

n-butyl phthalate

Cardiotoxic plants

• milkweed

• yew

• avocado

• cotton

• white snakeroot

• monkshood

• larkspur

Hepatotoxic plants

• cocklebur

• ragwort, rattlebox, comfrey

• blue-green algae

• lantana

• mushrooms

• Blue paricum kleingrass, punturevine, bunchgrass, agave

Nephrotoxic plants

• grapes/raisins

• oak

• pigweed

• shamrock, sorrel, dock, rhubarb

Castor beans

A source of medicinal castor oil, which is nontoxic, but they contain a very toxic substance called ricin that causes multiorgan failure if ingested

Cycad palms

Also known as sago palms, contains the toxic compound cycasin, which causes GI signs and hepatic toxicity

Lillies

Cats are very vulnerable to it, and it causes renal failure and death

Oxalate crystals

are contained in plants such as philodendrons and dieffenbachia species

Cats are more sensitive to

concentrated permpethrin preparations (common flea meds) than in dogs and exposure can lead to muscle tremors and seizures

Methocarbamol

can be used to treat muscle tremors, and seizure-control meds, such as barbiturates and diazepam, can be used to address the seizures

Several common household plants contain

insoluble calcium oxalate crystals

Anticoagulants in rodent baits

Are a source of toxicity for companion animals

Ethylene glycol

The most hazardous form of antifreeze

Cats are more sensitive to

acetaminophen than dogs

Acetaminophen toxicity causes

methemoglobinemia, hypothermia, hepatic necrosis, and possible death

The tuberculosis medicine isoniazid

Can cause life-threatening seizures and decidosis

Ethanol can cause

CNS, depression, hypotension, arrhythmias

Cocaine can cause

CNS excitement, hyperthermia, tachycardia, seizures

Meth can cause

increase blood pressure, tachycardia, ataxia, mydriasis, hyperactivity, tremors, seizures

Marijuana can cause

When dried or heated, ataxia, hypothermia, disorientation, urinary incontinence

Wound healing

Is the overall process by which the skin and associated tissues repair themselves

Wound healing can be delayed due to

patient factors, such as diabetes, or corticosteroid treatment

3 phases of wound healing

inflammatory, proliferation, maturation

Inflammatory (lag) phase

(3 to 5 days) begins immediately, injured blood vessels leak blood components, leading to local swelling, and damaged cells and pathogens are removed from the wound by macrophages and neutrophils

Proliferation phase

Characterized by a rebuilding of tissue with collagen and extracellular matrix, myofibroblasts function to help contract the wound edges to bring them closer together

Maturation phase

Is the remodeling phase and begins approximately 3 weeks after injury; it can continue for years

Puncture wounds

are caused by pointed and sharp objects or bullets, these create small holes that can be deep

Abrasions

are characterized by superficial layers of skin that have been scraped away

Incisions

are cuts made by a sharp object such as a scalpel

Lacerations

are tears in the skin and deeper tissues

Avulsion

is tearing away a large section of skin, a degloving injury is this type that’s torn away from the underlying tissue, resembling how a glove is removed

Burn wounds

are caused by heat, electricity, chemicals or radiation

First-degree burns

are superficial and involve only the epidermis

Second-degree burns

are partial-thickness injuries that may form blisters

Third-degree burns

are full-thickness injuries forming an eschar (dead dermis tissue that’s dry and dark

Ulcerations

are formed by tissue eroding away

Bite wounds

can have a combination of puncture, laceration, and crushing characteristics and are usually contaminated

Pressure sores

are ulcerations caused by prolonged skin pressure

The goal of debridement

Is the removal of obviously contaminated, devitalized, or necrotic tissue and elimination of foreign debris from the wound

Wound closure is typically based on

The approximation of tissue edges during the healing process

Primary or first intention healing

wound healing that occurs when the wound edges are approximated, and granulation tissue formation doesn’t occur

Delayed primary closure

Wound healing in which the wound is left open to allow drainage and then surgically closed before granulation tissue forms

Secondary or second intention healing

A type of wound healing in which the formation of granulation tissue fills the wound

Secondary closure or third intention healing

Wound healing in the wound is cleaned, observed for infection development, and then surgically closed

Wound drainage isn’t necessarily

a sign of infection

The normal inflammatory exudate (a serosanguinous clear fluid)

may be copious and it may benefit from the placement of drains (such as a penrose drain)

When an infection is present in a wound, signs such as

swelling, heat, pain, and redness are seen in or around the wound area

Most bandages are composed of 3 layers:

the primary, secondary, and tertiary

The primary layer

contacts the wound

The secondary layer

serves as cushioning

The tertiary layer

protects the 1st 2 layers

Moisture-retaining layers are

the preferred primary bandage layer for most wounds due to improved epithelialization

Robert Jones Bandages

They’re used to provide temporary support for injuries located distal to the elbow and stifle joints in dogs and cats, most commonly used in small animals

Modified Robert Jones Bandages

They’re soft, padded bandages used more often than the traditional one

Casts are used to provide

stability for joint injuries or fractures, temporary presurgical support, treatment, and additional support after bone surgery

Preferred material for casts used in small animals

lightweight, rigid fiberglass casting tape

Spica splints

are used to immobilize any forelimb or hindlimb joint

Ehmer slings

are used to protect the hip joint after an injury, they maintain the femoral head in the acetabulum after a dosed reduction of a craniodorsal coxofemoral luxation

Hobbles

are used to prevent limb abduction for ventral coxofemoral luxation

Non-weight-bearing slings

aren’t maintained for more than three weeks due to the risk of joint and muscle contracture

Proud flesh

Horses that develop exuberant granulation tissue during wound healing

The splint material most commonly used for horses

Polyvinylchloride (PVC) pipe due to its lightweight and strength