Botulism

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Clostridium botulinum under electron microscopy[1]

Botulism is a systemic toxemia in dogs caused by Clostridium botulinum.

Toxemia associated with this disease is often seen in dogs that have consumed C. botulinum type C exotoxin or spores present in carcases of birds[2]. The ingested preformed toxin, absorbed into the blood, binds to nerve terminals and blocks release of acetylcholine. The result is flaccid muscle paralysis. Death is due to cardiac and respiratory arrest[3].

Clostridium botulinum produces 7 potent neurotoxins, but only 1 type (type C, BoNT/C) has been implicated in botulism in dogs[4].

Clinical signs in affected dogs are usually vague initially, followed rapidly by progressive tetraparesis/plegia[5] due to peripheral nerve dysfunction. Other signs such as facial weakness, dysphonia and respiratory compromise are common[6].

Diagnosis requires demonstration of the toxin via ELISA in serum, feces[7], vomitus, or samples of the ingested food[8]. It is often difficult to make a definitive diagnosis of botulism because circulating toxin levels are often low, source material may be absent, and available analytical methods lack sensitivity[9].

Differential diagnoses would include tick paralysis, myasthenia gravis, coral snake poisoning, idiopathic acute canine polyradiculoneuropathy (Coonhound paralysis)[10] and lasalocid poisoning[11].

Electromyography and electroneurography are usually supportive of a diagnosis[12] and affected dogs have characteristic prolonged insertional activity, low amplitude of the evoked muscle action potential, decreased amplitude of muscle action potential and slowing of motor and sensory velocities in the peripheral nerve[13].

Treatment is usually supportive. Placement of a urinary catheter is usually required due to retention overflow.

Broad-spectrum antimicrobials are often indicated, such as cephalosporin 15 mg/kg twice daily. Gastric feeding tube are recommended in dysphagic dogs.

Most dogs eventually recover in 1 - 2 weeks.

References

  1. Vetnext
  2. Borst GH et al (1986) Type-C botulism in dogs. Tijdschr Diergeneeskd 111(22):1104-1105
  3. Merck Vet Manual
  4. Kalluri P et al (2003) An outbreak of foodborne botulism associated with food sold at a salvage store in Texas. Clin Infect Diseases 37:1490–1495
  5. Wallace V & McDowell DM (1986) Botulism in a dog - first confirmed case in New Zealand. N Z Vet J 34(9):149-150
  6. Bruchim Y et al (2006) Toxicological, bacteriological and serological diagnosis of botulism in a dog. Vet Rec 158(22):768-769
  7. Farrow BR et al (1983) Type C botulism in young dogs. Aust Vet J 60(12):374-377
  8. Thomas RJ (1991) Detection of Clostridium botulinum types C and D toxin by ELISA. Aust Vet J 68(3):111-113
  9. Galey FD et al (2000) Type C botulism in dairy cattle from feed contaminated with a dead cat. J Vet Diagn Invest 12:204–209
  10. Bors M et al (1988) Neuromuscular disease in a dog. Cornell Vet 78(4):339-345
  11. Safran N et al (1993) Paralytic syndrome attributed to lasalocid residues in a commercial ration fed to dogs. J Am Vet Med Assoc 202(8):1273-1275
  12. Uriarte A et al (2010) Botulism in 2 urban dogs. Can Vet J 51(10):1139-1142
  13. van Nes JJ et al (1986) Electrophysiological evidence of peripheral nerve dysfunction in six dogs with botulism type C. Res Vet Sci 40(3):372-376