The companionship and pleasure derived from owning a dog cannot be calculated, but close association with pet dogs can have some serious effects on human health and we propose to discuss some of the more common of these together with some simple precautions.
The most important disease transmissible to the man from the dog is hydatids. This can be a deadly disease in which multiple cysts develop in the liver, lungs, brain, and other vital organs of humans.
The adult tapeworm carried by the dog is only a few millimeters long and causes the dog no inconvenience. Eggs pass out in the feces and contaminate the environment of the dog so that the infective stages of the parasite lodge on the animal’s coat.
Humans ingest the infective stage by patting the dog and failing to wash their hands before eating, kissing it, and by allowing the dog on to the bed or rug where children are playing.
Prevention of the disease in humans is comparatively simple. The dog becomes infected by being fed infected raw offal from freshly killed sheep or cattle. Dogs allowed to roam freely in country properties may find a freshly dead sheep or lamb.
They do not become infected themselves by merely associating with country dogs but infective eggs hazardous to humans can be passively transmitted from the coats of infected dogs to the household pet.
It can be seen that dogs carefully fed and living a suburban life have little chance of harboring hydatid tapeworm. Nevertheless it is very desirable that all dogs are routinely dosed with an efficient drug that acts on all tapeworm species including hydatids.
The other major parasite of dogs that is dangerous to man is the roundworm or ascarid.
For all practical purposes every puppy and the young dog must be considered as harboring roundworms. The life cycle of this parasite is so efficient that it is almost certain that all young animals are born with roundworms.
Worm eggs are passed in the droppings and also in the bitch’s milk, and infection of the unborn puppy can occur within the mother’s uterus.
Each mature roundworm produces hundreds of eggs so that the surroundings of the puppy can quickly contain massive numbers of eggs. The eggs are sticky and adhere to the animal’s coat, carpets, blankets, and child’s toys.
The eggs when swallowed by a human penetrate the intestine and are carried by the bloodstream throughout the body. Mature worms do not develop in the unnatural host but the wondering larvae can cause irritation in both skin and deeper organs. In some rare cases severe eye damage has been recorded as well as disorders of the brain and spinal cord.
Fortunately roundworms in dogs can be effectively controlled. It is now recommended that puppies should be treated at 2 weeks of age and again at 3 weeks. Then every 2 or 3 weeks until the puppy is 6 months. Female dogs should be treated before mating, in early pregnancy and again each time the puppies are wormed.
Children should be discouraged from rolling on the carpet playing with very young puppies and encouraged to wash their hands after handling. Pets and children alike must be trained early to practice good hygiene.