Calf Diphtheria

Calf Diphtheria

Oral necrobacillosis, Necrotic stomatitis and Necrotic laryngitis

 

Definition:

It is an infectious disease of calves characterized by ulcerative necrosis in the check, tongue, pharynx and larynx.

 

Etiology:

 

Fusobacterium necrophorum is a non-spore forming Gram negative obligate anaerobe and a normal inhabitant of the alimentary tract and the respiratory tract.

♦ The factors, which contribute to the pathogenicity of the organism, include a potent endotoxin, a polysaccharide capsule, an exotoxin (leukocidin) and a hemolysin.

♦ The organism is a common inhabitant of the gut and environment.

 

Epizootiology:

 

Geographical distribution: worldwide distribution.

Susceptibility: oral infection occurs in calves less than 3 months. A laryngeal infection is more common in older animals up to 18 months.

Sources of infection: saliva of infected animals and contaminated foods are the main sources of infection.

Transmission: infection occurs by penetration of the organism to the injured oral mucosa, which is caused by rough feed or erupting teeth.

 

Pathogenesis

 

The organism causes inflammation and necrosis of the injured oral mucosa, pharynx and larynx. Edema and inflammation of the mucosa of the larynx result in inspiratory dyspnea. Exudates can fill the lumen of the larynx and suffocate the calf. Swelling of the pharyngeal area develops. Fatal supportive bronchopneumonia and toxemia finally lead to death.

 

Clinical signs

 

  • Fever, depression and anorexia.
  • Necrotic stomatitis and necrotic ulcers in oral mucosa.
  • Salivation
  • Difficult breathing.
  • Moist painful cough and severe inspiratory dyspnea.
  • Swelling at pharyngeal region.
  • Spread to lungs causes fatal pneumonia, toxemia and death.

 

Post mortem lesions

 

  • Necrotic deep ulcers on the oral mucosa which are filled with necrotic material and covered with caseous material and diphtheritic membranes that bleeds when removed.
  • Similar lesions are present in pharynx and larynx (necrotic laryngitis).
  • In severe cases similar lesions are present in lungs and abomasums.

 

Treatment:

 

  1. Removal of necrotic material with application of antiseptic solution.
  2. Oral administration of sulphamethazine at a dose of 150 mg/ kg BWt daily for 3-5 days.
  3. Broad spectrum antibiotics can be used for up to 3 weeks.
  4. Non-steroidal anti-inflammatory drugs to reduce swelling and fever.
  5. Tracheotomy may be necessary.

 

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