01/07/2021
Calf Diphtheria
A case of calf diphtheria was diagnosed in a young calf on a cow-calf operation in southern Indiana. This case highlights calf diphtheria as a cause of death which can be prevented in calves.
The herdsman observed a week-old Charolaiscalf which was lethargic and becoming very distant from the rest of the herd. The calf had difficulty nursing, diarrhea, and made frequent painful swallowing attempts.
On physical examination, the referring veterinarian noted that the calfs breath had a fetid odor. The cheeks appeared to be swollen and a large lump was located in the left cheek. Excessive saliva dripped from the calfs mouth. The re**al temperature was 105F. Other clinical signs were tachypnea and loud wheezing. On examining the oral cavity, an ulcer was observed on the proximal aspect of the tongue and there was excessive pharyngeal edema. Based on the clinical signs, a diagnosis of calf diphtheria was made.
The herdsman stated that the mother, a first-calf heifer, would often leave the calf separated from the rest of the herd. He went on to say that the calf would continually bawl for the cow over an extended period of time. The veterinarian attributed the ulcers in the laryngeal and pharyngeal mucous membranes to be caused by the continuous bawling by the calf. The damaged oral mucous membranes allowed the secondary colonization of Fusobacteriumnecrophorum which is the primary cause of calf diphtheria.
The calf was given oral electrolytes by esophageal feeder and sulfamethazine boluses. However, the calf died within four days of the initial examination. On postmortem evaluation, several deep necrotic ulcers were present on the tongue, the inner surface of the cheeks, the lining of the pharynx, and the trachea. The cause of death was an acute necrotizing pneumonia which presumably resulted from aspiration of the infected oral tissue. The aspiration pneumonia may have been prevented if the sick calf had been noticed earlier and aggressive antibiotic therapy was immediately started. Frequently monitoring young calves on pasture is essential in identifying and preventing the spread of calf diphtheria.
Calf diphtheria is an infectious disease affecting the pharynx, larynx, and oral cavity. Fusobacteriumnecrophorum is part of the normal flora of the mouth, intestines, and ge***al tract of herbivores and omnivores. The organism is also widespread in the environment (Frasier, 1991). Fusobacteriumnecrophorum is considered to be a secondary invader instead of a primary cause of disease. The organism leads to infection by gaining access through traumatic injury of the oral mucous membranes.
Diphtheria most often occurs as necrotic stomatitis in calves less than three months of age, but usually occurs as necrotic laryngitis in older calves. As in the case previously discussed, necrotic stomatitis caused fever, depression, anorexia, excessive salivation, and a fetid smelling breath. Loud respiratory wheezes are most often observed in older calves with necrotic laryngitis. Some cases have been reported where calves have both necrotic stomatitis and necrotic laryngitis. If calves go untreated, death usually occurs in two to seven days from toxemia and pneumonia (Fraser, 1991).
The diagnosis of calf diphtheria is usually based on the clinical signs. Differential diagnoses include pharyngeal trauma, IBR,actinobacillosis, laiyngeal edema, trauma, paralysis, tumors, and abscesses (Smith, 1996). Lesions identified on necropsy include marked edema, hyperemia, and swollen oral, pharyngeal, and laryngeal mucous membranes surrounding a necrotic ulcer. In chronic cases, an ulcer may extend into the nasal cavity, trachea, or lungs. In smears from deep in the lesions, filamentous, beaded, gram-negative bacteria may be identified. The bacteria may also be cultured on blood agar in an anaerobic environment (Frasier, 1991).
Sulfonamides (140 mg/kg IV loading dose followed by 70 mg/kg daily) or procaine penicillin G (22,000 U/kgIM or SQb.i.d) are the drugs of choice (Smith, 1996). Flunixinmeglumine or aspirin may be given to reduce the fever and inflammation. Supportive care in the form of oral or IV fluids, shelter, adequate ventilation, and easy access to food and water is very important. The prognosis is good if the infectious disease is detected very early and aggressively treated. If animals are closely confined, the spread of this infectious disease can be prevented by thoroughly cleaning and disinfecting all calf feeders. Young calves must be examined daily to identify early stages of the disease.
This report serves as a reminder, that even though it occurs infrequently, cases of calf diphtheria are still diagnosed. With early detection, aggressive parental antibiotic therapy, and supportive care, complete recovery is likely.
