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PARASITE CONTROL IN THE DOG, NORTH AMERICA
by Fred Lanting
Copyright July, 2008 -
WORMS
Most worms (nematodes) settle and grow in the small intestine, though some species are found in the cecum, heart, lung, and other tissues in various stages of development. The intestinal nematodes produce eggs, which are carried with the digestive products to exit in the feces. But since the egg-laying does not always coincide with the dog's bowel movements, stool samples may not show the presence of worms. A 5 day sampling will probably reveal some eggs if hookworms or roundworms are present, but tapeworms or whipworms may still escape detection. For this reason, many breeders rely instead on outward signs of poor coat, flatulence and/or diarrhea, loss of weight, and an abnormal look or smell to the stool.
In many breeds, the topcoat should lie flat, straight, and smooth, giving a water resistant thatch over the softer undercoat and skin. If these coarse, straight guard hairs stand up and out, or if the ends curl out away from the body, it may be a temporarily "open" condition due to worms. Luster and texture also is gone, and the feel is rough and dry, the natural lubrications being lost when worms take their tariff from the intestinal lining's rich supply of blood vessels, or otherwise interfere with normal absorption of nutrients. In this article you will see the word anthelmintics, which is the more accurate word for "wormer", "worm medicine", etc.
Roundworm — This is the most widespread of parasitic worms in dogs, cats, and many other animals. They are present in almost all newborn pups, having passed in larval stage through the placenta into the fetus's liver. After birth, these larvae are carried by the blood to the heart, then to the lungs. Irritation of the bronchial passages causes the dog to gag and cough the larvae up, then swallow them. This enables the larvae to reach the intestines where they latch onto the walls with lamprey-like tenacity, and in as few as ten days can be found to have matured into identifiable roundworms of egg laying capacity.
Older pups that get worms a second time usually do so by ingesting worm eggs from stool or stool-contaminated surfaces. Pups (and adults) may also pick up roundworms from cat stools, which present a tremendous attraction. Larvae have also been detected in bitch's milk. Swallowed roundworm eggs hatch in the intestine where the liberated larvae penetrate the wall and are carried in the lymph system to the veins. They, too, take the liver heart-lungs route, molt, and start laying eggs of their own four weeks after being ingested. So, it's a good idea to repeat initial worming a couple weeks later, whether it's a new litter or a dog you have just obtained but aren't sure of its worming history (such as may be the case with some imports).
Adults and half grown dogs tend to trap some roundworm larvae in body tissues in an encapsulated or encysted condition, where they do no further harm. Pregnant bitches, however, undergo a hormone change about three weeks before whelping that releases the encysted larvae, freeing them to migrate to the placenta and affect the fetuses as the bitch herself was affected when she was a growing embryo. This dormant stage of roundworm larvae can also exist in transient or intermediate hosts such as rodents, and if mice are eaten, the process of digestion will release the larvae in the dog's intestine, where they will not migrate (because they are in a different form), but develop into roundworms. Dogs that catch and eat beetles, cockroaches, mice, even earthworms, all of which may be hosts for roundworms, should periodically be given anthelmintics (wormers) as a routine control measure. Pyrantel pamoate (Strongid™, Nemex™) is an excellent anthelmintic for the youngest puppies because it is considered non-toxic and very safe even if rather overdosed accidentally; it is highly effective against round and hookworms. A good routine is to administer 2 weeks after birth, and then again 10 days after that. The next worming can be with ivermectin, but if you have a very small breed, you might want to dilute that. More on this anthelmintic drug later.
Hookworm — Hookworms are much smaller than roundworms and cannot be seen outside the dog, but as in the case of roundworms, eggs can be detected in fecal matter under the microscope. "Hook", as dog fanciers often call it, is a debilitating disease in adults and a frequent killer of pups. It is possibly the leading cause of death in puppies over two or three weeks of age. In chewing their way to blood vessels serving the intestinal walls, hookworms inflame the lining and make the organ less efficient. As a result, the dog becomes malnourished as well as anemic. Bloody stool, diarrhea, anemia, weakness, and dehydration are symptom of hookworm infestation, in addition to the sign of poor coat condition. There are a number of good anthelmintics, but the one I find most convenient, safe, and effective is ivermectin, good not only for heartworm prevention, but also for preventing and treating for round, hook, whip, and even ticks. Interceptor™ (milbemycin) is another heartworm "medicine" that gets many of these parasites. Since all wormers are potentially dangerous especially to debilitated pups, follow your veterinarian's orders when worming sick or very weak pups. Hookworm can commonly be picked up at dog shows, veterinarians' lawns and lobbies, city sidewalks, and parks where dogs defecate. The eggs can live a long time in the soil, but sunlight helps to kill them, and full strength chlorine bleach can destroy or force them to hatch and thus be susceptible to attack by products available from your veterinarian.
"A whip so small you could not see it, I've known to lash the mighty creature till it fell."
…Emily Dickinson, 1874
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A well-respected and frequent GSD specialty and all-breed judge for many clubs around the world, with KC and other-country credentials, Mr. Lanting since 1966 has lectured on Gait-and-Structure, Canine Orthopedic Disorders, and other topics, and has judged in about 30 countries, including the prestigious FCI Asian Shows hosted by Japan Kennel Club and the KC of India, the Scottish Kennel Club, and many National Specialties in the USA and elsewhere. He has been described by a former OFA director as the world’s leading non-veterinarian authority on hip dysplasia. A dog breeder since 1945, a GSD owner since 1947, and a show judge since 1979, he has lectured at numerous veterinary schools in the USA and abroad. He is the author of “must read” books for the dog owner (see below for ordering info). Curriculum Vitae available upon request.
Announcing the new “Canine HD and Other Orthopedics Disorders” book: The expanded revision is a comprehensive (nearly 600-page), amply illustrated, annotated, monumental work that is suitable as a coffee-table book, a reference work for breeders and veterinarians, and a study adjunct for veterinary students. It is equally valuable for the owner of any breed. It covers every aspect of HD and other orthopedic, bone, or spinal disorders, and includes genetics, diagnostic methods, treatment options, and the role of environment. Your autographed copy will be mailed from the USA as soon as the appropriate amount is received and is processed. Pricing: US $68, plus $5 postage in the U.S., or ask about mail overseas. Combine orders with “The Total German Shepherd Dog” by the same author ($50 plus postage). 17 of the 20 chapters are suitable for owners of any breed.
