In carrying out CBPP diagnosis it is necessary to differentiate this disease from other diseases that may present similar clinical signs or lesions. Remember that the disease pattern in a herd is as important as the findings in a single animal when carrying out an investigation.
Some sources of confusion are:
Rinderpest: The confusion with rinderpest results from the fever and discharges observed from the eyes, nose and mouth. However, the characteristic lesions of rinderpest, which are essentially erosions in the mouth and throughout the digestive tract, together with the profuse, often bloody diarrhoea in advanced cases, should enable easy differentiation from CBPP in which these are not seen. Lung lesions are seen in more chronic cases of rinderpest, consisting of red areas of collapse together with emphysema of lung lobules and the septa separating them. At this stage, the erosive lesions of rinderpest may have healed.
Foot-and-mouth disease (FMD): Salivation, lameness and fever are the cause of confusion.
Haemorrhagic septicaemia (HS): This is an acute disease and most affected animals die within 6 to 72 hours after the onset of clinical signs. Buffaloes are particularly susceptible. Oedema of the throat and neck to the brisket is often very pronounced. The lung lesions seen in animals that survive the longest can appear very similar to the marbling lesion of CBPP. There may be yellow fluid in the chest cavity and the affected lung may adhere to the inside of the rib cage. Thus, in the individual case distinguishing between HS and CBPP can be difficult.
Bacterial or viral broncho-pneumonia: Clinical signs may resemble closely those of acute CBPP. Post mortem examination shows usually both lungs to be affected, fibrinous exudate may be present but not to the same extent as in CBPP. While dark, solid areas of lung may be seen, these are usually restricted to the anterior lobes (not the diaphragmatic lobe as in CBPP) and marbled lungs are not often seen.
Theileriosis (East Coast Fever): Coughing, nasal and ocular discharge and diarrhoea are observed. Affected cattle show general enlargement of superficial lymph nodes and especially those of the head. The lungs contain much clear liquid, which is also present in the chest cavity; the airways in the lung may be filled with white froth. “Cigarette burn-like” ulcers are seen in the abomasal folds. Neither pneumonia nor inflammation of the pleura is present.
Ephemeral fever: In most cases this is a self-limiting disease of short duration; most affected cattle recover quickly, even those which are severely affected. The fever fluctuates with two or more peaks. Pneumonia is not a main feature of the disease but a secondary pneumonia can occur with lung oedema and emphysema in a small proportion of cases. Confusion with CBPP arises from the presence of fever, discharges from the eyes and dripping of saliva from the mouth, lameness and swollen joints (but in animals of all ages, unlike CBPP).
Abscesses: They can be mistaken for sequestra. When cut open the content of abscesses is often offensive smelling, consisting of liquid purulent material. In abscesses a total destruction of the lung tissue occurs. Old, thickly encapsulated hydatid cysts can also cause some confusion.
Tuberculosis: Tubercular nodules can superficially resemble sequestra but they are degenerative cheese-like lesions, sometimes calcified. The lung tissue is destroyed and the same lesions are also seen in lymph nodes in the chest. The capsule of the tubercular nodules is not well defined when compared to that of sequestra.
Farcy: The lung lesions of farcy differ from sequestra as they are filled with foul smelling purulent material, as described for abscesses. Similar lymph node lesions are always present.
Actinobacillosis: The pulmonary lesions, when found, could be mistaken for sequestra. Lesions are generalized and seldom present in lungs alone.
Echinococcal (hydatid) cysts: These cysts have a double wall and contain a clear liquid, often calcified when old.
Foreign body reticulum pericarditis: Clinically similar to CBPP because of the dyspnoea associated with the disease. Only one animal is usually affected.