In glanders the nodular submaxillary enlargement is almost pathognomonic and still more so if the facial lymphatic vessels are thickened (corded) and both symptoms fail in purpura. In cutaneous glanders with swollen joints or limbs the attendant pain is much more severe, and the farcy buds, forming on the thickened and indurated lymph vessels, bursting and discharging an albuminoid fluid like oil have no counterpart in petechial fever. In cases of doubt the search for the glander bacillus, and above all the inoculation of a male Guinea pig in the flank and the discovery of the bacillus mallei in the resulting exudate and diseased testicle will decide. From _anthrax_ and _emphysematous anthrax_ petechial fever is distinguished by the absence of the large bacilli of these respective diseases from the exudate. It is not communicable, like anthrax, to the sheep, Guinea pig and rabbit, and does not crackle on manipulation, like emphysematous anthrax. The swellings are much more generally diffused than in anthrax and the hyperthermia much less. _Urticaria_ furnishes a skin eruption which may be indistinguishable from the earlier skin lesions of petechial fever, but these lesions are not associated with the petechiæ in the nasal and other mucosæ, and the swellings do not advance to great sanguineous engorgements, cracks, fissures, necrosis, and deep and extensive sores as in purpura. Urticaria is, moreover, usually traceable to some digestive disturbance and fault in feeding. _Malignant œdema_ is usually confined to the seat of the inoculation wound and an extension around that, the exudate is very watery and may be mixed with fetid gas bubbles, so as to crepitate slightly, and it contains an abundance of its specific, round ended bacillus, often in chain form. The carcass putrefies with great rapidity. _Horse pox_ affecting the pastern and limb with attendant swelling is distinguished by the absence of petechiæ on the mucosæ, and by the formation on the affected part of little pea-like papules, which early exude an abundant liquid, the concretion of which on the hairs forms a remarkable yellowish encrustation, embedded in the angry red sores beneath.