Diseases of Domesticated Animals

Gapes, due to worms in the wind-pipe causing the bird to gasp for breath, affects mainly young chicks. Gape-worm eggs passed in the bird's faeces contain larvae after ten days' time, and may hatch ; infestation is caused by swallowing free larvae or eggs containing larvae. Prevention is by isolation. Turkeys frequently carry the parasite, and should not run with chickens.

Fowl Cholera, very rare in Great Britain, is caused by B. avisepticus. It is characterized by profuse diarrhoea and is highly fatal. The intestinal mucous membrane usually shows acute in flammation and small haemorrhages are frequently present in the heart.

Fowl Plague, due to a filter-passing virus, has an incubation period of 24 to 48 hours; treatment is useless.

Parasitology.

The small intestines of colts are frequently infested with Ascaris equorum, producing malnutrition and anaemia, but the large intestine is the great worm reservoir for the horse. Here the strongyles are found, of which both larvae and adults induce disease. The former taken in with the food, pene trate the mucous membrane, reach certain tissues and blood vessels and finally return to the bowel. Sclerostoma tetracantha has a similar cycle except that it does not enter the blood vessels or distant tissues. Its symptoms are emaciation, foetid diarrhoea and weakness. The egg-laying females of Oxyuris curvula pass from the bowel to the anal region and produce pruritus. The botfly passes its larval stage in the stomach and when the larvae are numerous may cause disease. In sheep and cattle the common

fluke Distoma hepaticuon infests the liver, causing the highly fatal "liver rot." Small stomach strongyles produce serious effects in young cattle and lambs, with inflammation and diarrhoea, fol lowed by death from exhaustion. In cattle, sheep and pigs small thread-worms induce bronchitis, husk, and pneumonia. None of these parasites multiplies inside the host ; eggs and larvae pass to the exterior in the droppings or sputum, undergo certain changes, and return with the food. Tapeworms infest the domestic ani mals, particularly dogs and lambs. The larval Hydatids, or bladder-worms, are found in various organs, brain, liver, muscles, etc., causing giddiness and paralysis. Pigs are frequently infested with Ascaris lumbricoides, which may cause obstruction when numerous, and may wander into the bile ducts and induce fatal jaundice. External parasites cause disease of the skin, e.g., mange, scab and ring-worm in all domestic animals. Ticks and various flies are responsible for transmitting diseases due to blood parasites, e.g., redwater in cattle (England), Texas fever, equine biliary fever, jaundice in dogs, surra in horses and camels, heart water in ruminants (South Africa). Much advance has recently been made in the treatment of these diseases by organic com pounds of arsenic, antimony, etc.