Over the past few months, we've discussed in great detail external parasites commonly found on our pets; including ticks, fleas and mites.Today, we delve beneath the skin and start our series on intestinal parasites in dogs. Although it is difficult for us to know when our pets have internal parasites because we cannot see them, intestinal parasites are one of the most common problems that veterinarians see in dogs. Most of these parasites are so well-adapted to the host dog, they live in balance and cause no observable health issues. However, when the parasites become too numerous, the pet's health is affected and it is therefore best to keep your pet on a preventative treatment programme so he iskept free of parasites before the balance is disturbed.
The four most common intestinal parasites in dogs are hookworms, roundworms, whipworms and tapeworms.There are quite a few species of hookworm but only four affect dogs, the most common species being Ancyclostoma caninum. They thrive under conditions of high temperature and humidity.Hookworms are small, thin worms about 0.6 to 1.3 cm long that fasten to the wall of the small intestine to suck blood and tissue fluid. The life cycle of the hookworm includes eggs, larvae and adults: male and female adult worms in the intestine mate, and the female lays about 30,000 eggs per day; the eggs are shed in the faeces of the dog; under the right environmental conditions, the eggs incubate and after 48 hours hatch into larvae that can survive for up to two weeks in warm, moist soil; the larvae are able to penetrate the skin of the paw, and once inside the body, they migrate through the vascular system to the lungs and from there up the trachea, and are swallowed. The larvae then pass down the oesophagus and enter the digestive system, finishing their journey in the intestine, where the larvae mature into adult worms within five�seven weeks.
There are five routes by which puppies (and adult dogs) can acquire the infection:
�2 Migration through the placenta in utero
�2 Ingesting larvae in mother's milk
�2 Ingesting larvae in the soil
�2 Direct penetration of the skin (usually through the pads of the paws)
�2 Ingesting an intermediate host such as a rodent
Most serious cases of hookworms in puppies result from transmission through their mother's milk, and occur during the first two months of life. Most of those worms reach the animal's small intestine where they do severe damage, and symptoms include bloody or tar-like diarrhoea.In puppies over three months old, many of these ingested larvae become encysted (trapped) and remain dormant in the pet's muscle and connective tissue. These as well as hookworms that have not yet arrived at the intestine are why puppies and heavily infested adult dogs need more than one worming. In adult dogs, the most common routes of infection are ingesting larvae and larvae migrating through the skin. These dogs become carriers via larvae encysted in their tissues. During periods of stress or illness, these larvae are released and a new outbreak of bloody diarrhoea occurs as worms appear in the intestines.
Adult dogs with chronic hookworms often have no symptoms. When symptoms do occur, they include tarry or bloody diarrhoea, pale mucous membranes caused by anaemia, weight loss and emaciation, and progressive weakness. Symptoms can appear as early as ten days after exposure. The diagnosis is made by finding eggs in the faeces, so your veterinarian will ask for a stool sample from your dog in order to confirm the presence of hookworm.While adult hookworms in dogs do not affect humans, the larvae can burrow into human skin causing itching. Although the larvae do not develop into adults in the human host, they migrate through the body and cause damage to eyes and internal organs.In rare cases the larvae have been reported to penetrate into the human intestine where they partially mature and cause enterocolitis (intestinal inflammation).Strict hygiene (washing hands and bathing), wearing shoes when outside, and prompt disposal of dog faeces are all important in preventing the transmission of hookworms to humans.
Copyright � Kristel-Marie Ramnath 2014. For further information, contact 689-8113 or bestpetsbehave@ hotmail.com