54. Internal Parasites

These are the worms that live inside pigeons. Round worms are by far the most numerous. Tape worms are occasionally found in pigeons, but seldom present a serious problem.

a. Ascarids, or common large round worms are the largest and most prevalent of the round worms. Adult worms are from 1 to 2 inches long.

(1) Habits. Knowledge of the life cycle of a round worm is of great importance for successful control of this troublesome parasite. This worm has a “direct” life cycle ([fig. 47]) (completing it in one species).

(a) Mature worms live in the upper part of the small intestines and feed by absorbing food from the intestinal contents through their own body walls.

(b) Eggs (ova) are deposited by female worms in the intestinal contents of the pigeon, and later pass out in the pigeon droppings. It has been estimated that female worms lay as many as 12,000 eggs a day. Feces from parasitized birds often contain countless numbers of ova.

(c) Freshly deposited worm eggs are much like freshly laid pigeon eggs, in that they must be incubated before they are ready to hatch. They need to remain in warm, moist litter or soil for 10 to 16 days before the worm larvae can develop. Severe freezing, excessively hot soil, and direct sunlight will destroy the eggs.

(d) When birds eat the incubated eggs, the worms hatch out in their intestines.

(e) The tiny larvae then “sew” themselves into the lining of the intestines and begin to grow.

(f) After a few days, the larvae crawl back into the intestinal canal where they mature in 30 to 40 days.

(2) Diagnosis. Ascarids injure birds in several ways.

(a) When the newly hatched worm “sews” itself into the intestinal lining the area around the puncture becomes inflamed because of mechanical injury, loss of blood, and introduced infection. This localized inflammation renders that part of the intestinal lining useless for digesting and absorbing food.

(b) The worm absorbs food from the intestinal contents which should go to the birds.

(c) In order to protect themselves and avoid being digested, the worms give off a substance that neutralizes digestive juices. This substance becomes mixed with intestinal contents and prevents proper digestion.

(d) Worms sometimes become so numerous that they actually clog the intestines. As many as 500 worms have been found in a single bird.

(e) Worm-infested birds show loss of condition and general unhealthiness. Diagnosis is made by finding worms or worm eggs in droppings or by autopsy on typical specimens.

(3) Treatment. The following drugs are only effective against mature worms and, at best, are only 80 percent efficient:

1-CC Oil of turpentine per bird.
½-CC Tetrachlorethylene per bird.
½-CC Carbon tetrachloride per bird.

(4) Prevention. This is relatively simple and practically 100 percent effective.

(a) Clean loft daily and provide fresh water.

(b) If aviary does not have a wire bottom spread clean sand about 1 or 2 inches deep over its floor once every two weeks.

b. Strongyles are the most dangerous of the common round worms and one of the most common causes of death among poorly kept pigeons. The “strongyle” is a very small parasite which multiplies rapidly and is a vicious blood sucker. Adult worms are from ½ to ¾ inches long and about the same size as thin thread.

(1) Habits. This worm has a “direct” cycle; that gives the key to successful control ([fig. 45]).

Figure 44. Life cycle of pigeon ascarids.

(a) Adult strongyles live in the upper intestinal contents, but may be found as far up as the crop.

(b) Strongyles are ravenous blood suckers.

(d) Eggs incubate in about 1 day, if conditions are favorable.

(e) Young larvae hatch out and molt about 8 hours later. These larvae again molt in about 3 days and are then infective. Thus, about 5 days elapse from the time the eggs are voided by the bird and the time the young larval worms hatch, molt, and become infective.

(f) The infective larvae are eaten by the pigeons. Then they pass to the intestines where they mature.

(2) Diagnosis. (a) Strongyles injure the birds by lacerating the intestine and sucking blood. After the parasite moves on, the laceration still bleeds considerably before a blood clot forms. Each laceration results in an area of infection and inflammation.

(b) Constant movement of the worms over the inflamed intestine adds to the irritation.

(c) Severe, and sometimes rapid, loss of condition and accompanying anemia are usual symptoms. Diagnosis is confirmed by finding strongyles in the intestine upon autopsy of typical specimens.

(3) Treatment. Treatment is not satisfactory. One-half CC doses of tetrachlorethylene may be tried.

Figure 45. Life cycle of pigeon strongyle.

(4) Prevention. The same methods prescribed for ascarids apply to strongyles.

c. Other round worms attacking pigeons are numerous, but only capillary worms will be discussed here. These are very thin, hair-like worms sometimes found in the digestive tract of pigeons from the crop down through the intestine. Their life cycle is direct. No satisfactory drug has been found to rid pigeons of this worm. Fortunately, their life cycle is similar to that of ascarids, and the same preventive measures are effective.

d. Tape worms, which are occasionally seen in pigeons, acquire a length of 6 to 8 inches.

(1) Life cycle. Tape worms have what is called an indirect life cycle, that is they must pass through at least two different species to complete it ([fig. 46]).

(a) Adult tape worms are found in the small intestine. Their bodies are made up of a head and segments. The head is essentially an anchor that fastens the worm to the intestine of the bird. The body segments form at the head and mature as they grow further from the head.

(b) Each segment contains both male and female sex organs and, as it matures, becomes virtually a packet of tape worm eggs.

(d) The tape worm’s eggs are then eaten by a snail, slug, beetle, or other insect which becomes the “intermediate host.” Here the tape worm undergoes a certain amount of development.

Figure 46. Life cycle of pigeon tape worm.

(e) If the intermediate host is eaten by a pigeon, the young tape worm attaches itself to the bird’s intestine and soon grows to maturity.

(2) Diagnosis. Tape worms harm the host by injuring the intestine at the point where they bury their heads, by absorbing food, and by giving off antenzymes.

(3) Treatment. Unsatisfactory.

(4) Prevention. (a) Pigeons must be well-cared-for and fed so that they will not care to eat the intermediate hosts.

(b) The method of prevention prescribed for ascarids is also applicable for tape worms.