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 rectal
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
genital 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.
References:
Frasier, Clarence M.ed,et.al.. The Merck Veterinary
Manual, Seventh Edition, Merck and Co. Inc..NJ, 1991,
p. 719.
Smith, Bradford P., Large Animal Internal Medicine,
Second Edition.Mosby, St. Louis,
1996, pp. 627-628.
- by Brad Cooper, Class of 1997
- edited by KathyClarke,DVM
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