The symptoms of pericarditis and of cardiac disorder usually accompany those of pleurisy. The tumultuous heart beats, often associated with soft, weak or even rapid pulse, and later, a deadening or muffling of heart sounds, as in hydropericardium are characteristic when present. With endocarditis the early tumultuous heart beats, with small weak pulse, irregular and sometimes intermittent, become complicated by a blowing or hissing murmur with the first heart-sound. In such cases clots of blood are liable to form in connection with the valves, and may cause sudden and early death. When the heart is involved the tendency to extensive infiltration of limbs and lower aspect of the trunk is much enhanced. (See diagnosis for table of phenomena in influenza, fibrinous pneumonia and contagious pneumonia respectively).
Symptoms of digestive disorder are usually in evidence. Even in the thoracic forms the mouth is dry, hot, and has an offensive odor; the tongue coated above, has often red margins and tip; it may even be yellowish; the gums may be swollen and dark red or violet especially around the incisors; mastication may be slow and unwilling; the pharynx maybe swollen; the pharyngeal and submaxillary lymph glands may be tumid and tender; and swallowing may be difficult.
Congestions of the stomach and intestines are indicated by inappetence, sometimes flatulence, passage of flatus, constipation with small, round, mucous-coated balls passed in small numbers, and by slight transient colics, pawing, looking at the flanks, and retraction of the abdomen. The retention of bile and destruction of blood elements are indicated in a deeper yellow of the conjunctiva and visible mucosæ, and in a yellow, brown or red color of the urine. There may be tenderness of the abdomen, but this, like the colics, is moderate, the senses being blunted by the attendant stupor which is usually even greater than in the thoracic forms. Urination may become frequent with straining, and the urine may become turbid, opaque, with flocculi of cystic epithelium and mucus, and even albumen. In from three to five days diarrhœa supervenes, the fæces becoming soft, pulpy, watery, glairy or bloody, and escaping through a permanently dilated sphincter. The diarrhœa may alternate with periods of torpor or complete inactivity, otherwise tenesmus of the rectum is marked. The exposed rectal mucosa is congested, of a deep red or it may be of a dark violet hue. Eversion is not unknown.
In the worst cases death may ensue by the third or fourth day, but in others the diarrhœa is critical and heralds an improvement which goes on to a speedy recovery. In still other cases the bowel troubles continue, the fever does not give way and the privation of food and rapid metamorphosis of tissue produce steady emaciation and fatal marasmus.
A striking feature of the gastro-intestinal disease is the extraordinary susceptibility to laxatives. So much is this the case that I have known of two drachms of aloes proving fatal by superpurgation in a large, mature Percheron horse. It is never safe to use laxatives in equine influenza until one has ascertained whether in the special form of the epizoötic in question the gastro-intestinal organs are or are not especially involved.
Disorders of the eye are so common or constant as to have procured for certain epizoötics the name of pink eye. They set in suddenly, and equally in both eyes, with infiltration of the lids and particularly of the mucosa which is of a more or less deep red, and may bulge between the margins of the eyelids, (chemosis). The flow of tears is profuse, seropurulent matter accumulates at the canthi and in the lachrymal sacs, vision is impaired and there is intolerance of light. The cornea becomes bluish, cloudy or milky white, with a red zone around its margin and, above all, on the adjacent sclerotic. In some cases the aqueous humor becomes turbid or flocculent, and the iris changes its clear, healthy dark lustre for a dull brown or yellow tint. The tension of the globe may be materially encreased. They are readily distinguished from recurrent ophthalmia by the attendant weakness, stupor and hyperthermia, and by their non-recurrence in case the patient survives.
The nervous symptoms are especially manifest in the sudden seizure, great prostration, extreme weakness, profound stupor or lassitude, the staggering gait, in bad cases, insensibility to voice, slap or, it may be, even to the whip, the rigidity of the loins, their insensibility to pinching, the difficulty of turning in a short circle, or of backing. The high fever, disproportionate to the appreciable local lesions, and its sudden improvement at the critical period, the excessive weariness and the disposition to lie down contrary to the habit of other inflammatory chest diseases are further indications.
This may go on to coma, there may be more or less complete anorexia, muscular trembling, paresis, especially of the hind limbs, or delirious manifestations indicating meningitis.
Rheumatoid attacks of the muscles and joints usually appear in the advanced stages of the disease, but may appear earlier. They may occur in any latitude but seem to be especially common in cold, damp, inclement northern regions, and at seasons when climatic vicissitudes are sudden and extreme. These may appear suddenly and disappear with equal rapidity, or they may last for a time during and even after an apparent recovery in other respects. When the joints are involved they usually become engorged with exudates in the synovial membranes.
Lameness in either fore or hind limb may assume an intermittent type developed by exercise and subsiding with rest, evidently bespeaking local arterial embolism, and in such cases it is likely to persist for months.