The two main causative factors, of paresis of the rumen on the one side and of specially fermentescible food and a multiplicity of microbian ferments on the other, must be recognized as more or less operative in different cases, and in many instances their combined action must be admitted. The tympany is the symptom and culmination of a great variety of morbid causes and conditions, and its prevention and treatment must correspondingly vary.
Symptoms. The whole left side of the abdomen being occupied by the rumen, its distension leads to an uniform swelling of that side, differing from that caused by simple excess of solid ingesta in being more prominent high up between the last rib and the outer angle of the ilium, and in giving out in this region a clear tympanitic or drumlike resonance on percussion. It has also a tense resiliency, like that of a distended bladder, easily pressed inward by the finger but starting out to its rotundity the moment the pressure of the finger is withdrawn. The distension caused by overloading with solids bulges out lower down, is not resonant but dull or flat when percussed, and yields like a mass of dough when pressed retaining the indentation of the finger for some time. The swelling of tympany, when extreme, rises above the level of the outer angle of the ilium and even of the lumbar spines on the left side, and if no relief is obtained the right side may undergo a similar distension.
Auscultation detects an active crepitation over the whole region of the rumen, finer in some cases and coarser in others, according to the activity of evolution and the size of the bubbles of gas. The crepitation is especially coarse and loud in fermentation of green food, and of spoiled potatoes or other tubers or roots.
In all acute or severe cases, there is anorexia, suspension of rumination, and the normal movements of the compressed bowels seem to be largely impaired, though the anus is protruded and a little semi-liquid fæces or urine may be expelled at intervals. The breathing is accelerated, short, and labored. The nostrils are dilated, the nose extended, the face anxious, the eyes bloodshot and the back arched. Froth may accumulate around the lips, or the mouth may be held open with the tongue pendent. Sometimes a quantity of gas may suddenly escape with a loud noise, but without securing permanent relief. The heart beats are violent and accelerated, the pulse increasingly small and finally imperceptible, and the visible mucous membranes are congested and cyanotic. Pregnant females are very liable to abort.
When the right flank as well as the left rises to the level of the lumbar spines death is imminent, and this may take place as early as fifteen or thirty minutes after the apparent onset of the attack. Death may result from nervous shock, from suffocation, or from the absorption of deleterious gases, or from all of these combined.
In the less acute cases the animal may live several hours before the affection terminates in death or recovery. As a rule he stands as long as he can and finally drops suddenly, the fall often leading to rupture of the diaphragm or stomach, to protrusion of the rectum, or the discharge of ingesta by the mouth and nose.
In still slighter cases relief comes through vomiting or more commonly through frequent and abundant belching of gas, the swelling of the flanks subsides, rumbling of the bowels may again be heard, and usually there is a period of diarrhœa.
Gases present. When the rumen is punctured before or after death so as to give exit to the gas in a fine stream it proves usually more or less inflammable, the lighted jet burning with a bluish flame. The usual inflammable ingredients are carbon monoxide, hydrogen carbide (marsh gas) and hydrogen sulphide, yet the relative proportion of the gases varies greatly with the nature of the food and the amount of gas evolved, carbon dioxide being usually largely in excess. The following table serves to illustrate the variability:
| Gas. | Pflüger. | Gmelin, from clover | Lassaigne. | Lameyran and Fremy, from clover. | Vogel. | Raiset. |
|---|---|---|---|---|---|---|
| CO | 60–80 | 5 | 29 | 5 | 27 | 74.23 |
| CO | 28–40 | |||||
| CH | 15 | 6 | 15 | 48 | 23.46 | |
| HS | 80 | 80 | ||||
| O | 14.7 | |||||
| N | 50.3 | 25 | 2.22 |
The most elaborate observations on this subject are those made by Lungwitz on the different aliments kept in closed vessels at the body temperature, and on similar agents fed for days as an exclusive aliment to oxen provided with a fistula of the rumen for purposes of collection. He found carbon dioxide to be the predominating gas in all cases, but that it was especially so in extreme tympanies and varied much with the nature of the food. The following table gives results: