tetanus- lock jaw

DEF
An acute, non-contagious disease of animals and man caused by Clostridium tetani invariably following some type of trauma or wound and characterized by hyperesthesia and tonic muscular spasms and sometimes leading to convulsions.
etiology

. Gram + sporeforming, drumstick rod - anaerobic and motile

. Multiple antigenic types - ten + - some with reduced virulence

Toxins of basically two components - Tetanolysin and

Tetanospasmin (most important)

Organism is found in soil (mostly) spore state) and in GI tract of many normal animals - Cultivated soils often support existence.

Spores withstand temperatures above 100 degrees C must have temperature above 115 degree C for 20 minutes to be sure spores are destroyed.
DISTRIBUTION

. Worldwide - likely to have more cases as you move nearer to the equator. However, measures of virulence end to indicate that some strains more distant from equator are much more virulent.

. Transmission

Most often subsequent to wound infection or following surgical and obstetrical procedure. Especially if instruments become contaminated with feces or soil.
Reported case in man arose following pecking by a hen. Tetanus neonatorum arises following umbilical cord infection.
Some animals, especially ruminants may normally have titers of antitoxin in the blood, indicating some low level field immunization.

. Susceptible Hosts

Table of susceptibility places Solipeds and man at the top. Next line will include sheep, cattle and swine.

Disease is rate in the dog and cat.

Extremely rare in poultry - High level nerve tissue insusceptibility

Turkey Buzzard almost totally immune.

Factors Influencing Susceptibility

a. Age - more disease in young - likely to have more injuries, surgical procedures (castration). Some build up a resistance with aging.

Pastures and Housing - Only as it relates to presence of objects predisposing to injury.

.Season and Climate - Probably no good relation- ship in animals. Studies in human tend to show slight increase or relationship to absence of protective clothing hence a warm weather problem.

. Economics

SYMPTOMS

. Incubation period is variable - most often 1-3 weeks.

Occasional cases in horses or boars following castration have developed within 72 hours.

Keep in mind that this disease doesn't always require a deep penetrating wound. A superficial skin scratch is often sufficient, especially for the horse.

Early signs include hyperirritability, slight alteration of gait showing some stiffness, prominence of the membrane nictitons, fixed ears.

Progressive signs - Fever to above 110 degrees F if animal has developed tetanic spasms, sweating,salivation, dilation of nostrils, attempts to chew, straw or hay often held in mouth - noise will usually cause animal to go into tetanic spasm. Animal is rigid - head and neck drawn backwards (Opisthotonos). Tail rigid and elevated.

Animals maintain consciousness and remain up if all possible. Dyspnea with developing respiratory failure in terminal stages.

Symptoms may come on gradually over period of several days or in some cases may develop rapidly within 24 hour periods and animal expires after proceeding to violent tetanic convulsion.

. Dictum of Hypocrites "such persons as are seized with tetanus die within four days or if they pass these they recover". Generally, the longer the incubation period the more gradual will you find the development of symptoms and the likelihood of recovery.

DIAGNOSIS
Based largely on classical symptomatology supported by history you may never locate the wound, but if found, smears taken from it for microscopic examination will confirm presence of Cl tetani.
D.D
Differential diagnosis should include

Strychnine poisoning

Tetanies related to mineral excesses or deficiencies

Stiff lamb disease

. Tying up syndrome in horses

. Botulism

. Rabies

. Poisonings, esp. insecticides producing CNS related twitchings and spasms.

POGNOSIS

Always guarded, but unfavorable in animals that have had short incubation period and developed violent spasms with exhaustion.

Recovery is generally slow

TREAT
Therapeutic approach - Steps to follow may vary

Neutralize toxin - can only be done with antitoxin. Question is raised whether toxin is irreversibly bound to nerve tissue.

Therapeutic dose of antitoxin is 100 units/lb body weight repeated in 24 hours and this often provesfutile.
Infuse antitoxin at would site and inject into tissue around.

Suppression of organism - use of antibiotics
Parenterally and locally - opening wounds for drainage (generally find only small amount of pus or fluid)
Wound therapy with oxidizing agents (This has merit though some report that it facilitates greater absorption of toxin).

.Sedation and Housing - Animals should be kept in well bedded stalls and special efforts made to prevent loud noises. While it is difficult to maintain animals in a complete state of calm and relaxation through t he use of muscle relaxants. Such drugs as succinglcholine (Sucostrin) and curare have merit in violent cases. Tranquilizers are likely to be given by most veterinarians for calming and sedative effect.

. Maintenance of adequate hydration and nutrition. Many animals will be unable to eat or drink - these should receive fluids and nutrients via stomach tube.

Keep water and feed at neck level - many animals cannot lower head to eat from the floor.
Oxygen Supply
Perform tracheotomy when indicated - Procedure hasn't generally been done in vet med for various reasons.
Hyperbaric chambers for increasing oxygen tension are useful at human level.

PREVENTION& CONTROL

Immunization

. Recommend Tetanus toxoid for equine species

Commercial preparations now in use are so concentrated that 1 ml injections of toxoid can be administered. Animals to be properly immunized should receive a second injection in 4-6 weeks and thereafter an annual booster injection.
Cattle, sheep and swine are seldom given toxoid, but consider its merit in valuable breeding animal.
Tetanus antitoxin provides passive immunity. Length of protection is probably no longer than 21 days in most instances and less if animal is subject to challenge.
Recommended doses --

Horses - always 1,500 units - more if treatment has been delayed.

Boars following castration 500-1,500 units.
Toxoid and antitoxin are generally used separately, but studies indicate they can be administered simultaneously in separate sites. The effect is one of reduced stimulation and effectiveness from the toxoid.

Sanitation

Be wary of using contaminated instruments - Discard needless, etc. that have been used at would sites -- 5% phenol is effective if kept in contact with surfaces for 10-12 hrs. Time can be reduced by adding 5% Hcl.3%. Formalin has been used - Bichloride of mercury is effective at 1-500, but has unfavorable action if corrosiveness to metals - Prolonged heat above 115 degrees C under pressure is always a good way to kill spores.

Burn carcasses to prevent spores from seeding soil.

Turn soil in paddocks and small lots to allow sunlight to act

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