Although fairly common in other situations, worms are most frequently found infesting the intestines and stomach.
The cavities of the heart, nasal and respiratory passages, cranial cavity, and bile-duct are more rarely the seats of parasitic invasion in the dog. When the heart and respiratory tubes are affected, the parasites are of a minute, thread-like character, hence known as Filaria, or thread-worms.
The flat, lancet-shaped worm, sometimes found up the nose, is spoken of as a trematode; the round-worms in the stomach and bowels as nematodes; whilst the other long, flat, or tape-like worms, are called Tænia.
Very few dogs are entirely free from worms of one sort or another, though it is only when these become numerous that the dog shows signs of having these pests.
Gradual loss of condition, irregular appetite, irregular evacuations, harsh coat, sometimes vomiting, and increased redness of the membranes lining the eyelids, are the usual signs, significant of internal parasites. Positive proof is of course the passage of segments of tape-worms, or round-worms, either by vomiting, or in the evacuations.
Sneezing and a catarrhal discharge from the nose is generally present when the nasal passages are infested with the lancet-shaped worms already alluded to. An uncommon true blood-sucking worm (Spiroptera sanguinolenta) is occasionally found in the stomach.
Newly-born puppies seem predisposed to become infected with round-worms, known as Ascaris marginata, such infection taking place from the dam, hence the necessity for ridding her of worms, and the most suitable time to administer vermifuge medicine, in an efficacious manner, is prior to her coming in season.
With reference to the preventative measures against worm infestation, speaking practically, not a great deal can be done, the sources of infection being so varied. Feeding dogs on the viscera of animals must of course be condemned, and with the abolition of this practice so will diminish one source of infection. Many so-called worm specifics are now largely advertised, rival proprietors claiming superiority and even infallibility.
Some of these nostrums are given without fasting the dog, but said to be equally efficacious. This statement must be accepted with reservation, as all worm medicines act more energetically when the stomach and bowels are empty. Before administering worm medicine, it is advisable to fast adult dogs for twenty-four hours, but puppies should not be kept longer than fifteen hours without food.
Although an old, but well-tried remedy against both round and flat worms, areca nut still maintains its position, and rightly so, because when given in suitable doses, and in accordance with the old rules, it seldom fails to give a satisfactory account of its action.