The fact that icterus usually sets in several days after such an exposure, whether in man or dog, indicates a period of incubation, and thereby sustains the theory of infection.
Symptoms. In the majority of cases, gastro-enteritis constitutes the first step of this affection and the early symptoms are characteristic of that disease. Frequent vomiting, at first of food, and later of a glairy fluid which may be discolored by bile, redness of the tongue, especially along its margins, bloodshot, watery eyes, lying down with the nose on the right side of the abdomen, or standing with the abdomen tucked up and the back arched, halting movements of the limbs, wincing if manipulation is made of the spine or the epigastrium, elevated temperature, accelerated pulse and breathing, anorexia and perhaps purging, mark the onset. So long as the liver is unaffected prostration is not a marked feature.
Even when the liver is invaded, a fair measure of life and activity may often be retained so long as the kidneys remain sound and active. The bile pigments and salts, and the toxins generated by the invading microbes are alike eliminated in large part in the urine, and the profound poisoning and prostration of the nervous system are in a measure prevented. In many cases therefore the urine is strongly jaundiced without much or any discoloration of the mucosæ and in such cases the prospects are usually good for an early and complete recovery. It must not, however, be inferred that such a happy issue will always follow, as the pigments are by no means as toxic as are other hepatic products and fatal results may ensue with very slight jaundice of the tissues.
As a rule, however, the jaundice of the tissues (eyes, nose, mouth, white portions of the skin) is to be accepted as a grave manifestation, indicating either an excessive production and absorption of bile, or a suppressed secretion through the kidneys, or both. Then the poisoning by biliary salts and bacterial toxins is shown in profound dullness, prostration, muscular weakness, indisposition to rise, moving stiffly and only when dragged by the collar, the limbs trembling and the back arched. The tender back is arched, the right hypochondrium sensitive, the expression dull, stupid and listless, and constipation or a fœtid diarrhœa is liable to set in. The heart beats may be strong and irregular, the breathing is easily disturbed and hurried. The temperature at first 104° to 107° may descend to the normal as the system becomes charged with the toxic products, and does not usually exceed 99.5° after two or three days of jaundice of the tissues.
The icterus is shown in the eye or mouth, or on any white portion of the skin, and in the urine it will be detected by the eye or by the tests above given.
In the worst cases the urine is very scanty and of a deep yellowish brown color, prostration is extreme, tympany, colic, obstinate constipation or bloody diarrhœa may set in, the breathing, hurried or not, is trembling, the pulse small, and the temperature at first high may descend to 95° or even much lower before death.
The course of the disease varies according to its gravity. If there is complete retention of bile, and abundant production of toxins, the animal dies in one or two days in a state of collapse. If there is general progressive degeneration and destruction of the hepatic tissue without at first absolute suppression of the discharge of bile into the duodenum, the patient may last till the fourth or fifth day, or later.
Lesions. There are usually congestion, tumefaction, friability, ecchymosis and even ulceration of the gastric and duodenal mucosa. The organs are empty, but show a reddish brown exudate of a glairy consistency, and containing red blood globules and pus corpuscles. The same inflammatory lesions are to be traced into the common bile duct, the cystic duct and bladder, the biliary ducts, and the acini. The mouth of the common duct is usually blocked with a plug of tenacious mucus, the gall bladder having been unable to expel this and the inspissated bile into the intestine. The liver is slightly enlarged, yellowish, with patches of brownish yellow more or less deep, and the acini contain an abundance of oily globules, and yellowish brown granules. The acini have no clear line of delimitation, and the contained hepatic cells are shrunken and distorted, standing apart from each other in a dropsical or watery medium.
The kidneys are congested and ecchymosed; the cortical substance brown, friable, and with numerous areas of necrosis of a bluish white color, and even abscesses. The medullary substance is yellow and the uriniferous tubes contain an abundance of yellowish brown granules.
The lungs have a yellowish red color, with patches of ecchymosis.