Tetanus outbreak in a sheep flock due to ear tagging

Abstract

Tetanus is an acute, often fatal, infectious neuromuscular disease in all farmed mammals caused by Clostridium tetani . The disease is sporadic but outbreaks of tetanus have been described, as a result of wound contaminated with spores of C. tetani , which sporulates to the vegetative form and produce toxins. The present study reports an outbreak of tetanus in a sheep flock, shortly after ear tagging. Three sheep from a large flock (with a population of 1000 sheep) were presented with signs of: convulsion, limb stiffness, incoordination and trismus (“lock jaw”). There were wounds and scabs in most livestock where ear tags had been attached 1 week prior. Clinical examination revealed tachycardia, dyspnoea with dilated nostrils, mild fever, erected ear pinnae, teeth grinding, mild bloat, muscles rigidity, prolapse of third eyelid and anxiety. According to the history stated by the owner, the case fatality rate of the disease from the beginning was 50% during the outbreak. Necropsy did not reveal any significant finding. Gram‐positive bacilli with terminal spores representing C. tetani were isolated in anaerobic cultures which were taken from ear wounds. Procaine penicillin G was administrated at 20 000 IU/kg BW for 5 days, but antiglobulin was not available to treat affected animals. Mortality significantly declined one day after onset of treatment. In this report, the organism was probably introduced by contaminated instruments which were used for ear tagging of sheep. Wound exudation and adhesion following rubbing, created a favourable anaerobic condition for the spores to germinate with production of neurotoxin. Vaccination can protect animals against tetanus, but it does not preclude the need to apply standard hygienic principles when performing management procedures causing wounds. In pasture holding system, many pathogens are present in environment, so tetanus should be considered important in farm animals, because of its high fatality rate and the long course of convalescence.

Tetanus in Animals — Summary of Knowledge

“…The tetanus wound can be very small and sometimes it is difficult to find it. Tetanus may develop even after the wound has com- [6,9,11,16,31].…”

Vaccine Production to Protect Animals Against Pathogenic Clostridia

“…Sadly, the improper sterilization of surgical instruments used to cut the umbilical cord is the principal cause of neonatal tetanus, a relatively common condition in developing countries with poor health infrastructure [14]. In animals, wounds caused by castration, tailing, tagging, shear cuts, and fight bites are associated with C. tetani infections [4,72,73,74]. Horses are the most susceptible animals, followed by small ruminants [4,75].…”

“…The mortality rate of tetanus cases in both humans and animals is high [4,87,88]. Nevertheless, tetanus can be effectively prevented by vaccination.…”

“…Some pathogenic Clostridium species can reside inside the host as part of the normal microbiome or as latent spores without apparent adverse effects [4,5,6]. However, alterations such as the disruption of the gut microbiota by the use of antibiotics, damage caused by medically induced abortions, parasites, radiotherapy, chemotherapy, or diseases such as cancer or neutropenia can favor Clostridium pathogenesis [3].…”

“…Animal clostridiosis infections are probably more frequent and certainly less reported than human clostridia infections. Practices without the proper hygiene control, such as animal castration, vaccination, foot-trimming, marking, dehorning, dog bites, or the improper care of birth associated wounds are important contributing factors to tetanus, botulism, or gas gangrene in animals [4,17,18,19]. The sudden change in feeding or the improper supplementation of protein and phosphorus can lead to pulpy kidney or botulism [12,18].…”