There are various intestinal worms that can infect dogs and cats, with hook worms, round worms (ascarids), whip worms (mainly in dogs) and tapeworms being the main groups. Symptoms can include diarrhoea, bloody stools, weight loss, anaemia, pot belly, dry hair and/or general poor appearance. If left untreated, worm infestations can be fatal. Worms can be picked up from the mother (either in utero or via milk), from the environment (infected stools), from eating infected prey (lizard or mouse), or, in the case of tapeworms, from fleas. Worms can also be transmitted to humans.
Giardia intestinalis and Giardia duodenalis are single celled protozoan parasites, which inhabit the affected dog’s small intestine, causing clinical signs of Gardiasis. The protozoa attach themselves to the intestines and multiply. They may be directly swept through the intestines and appear in the infected dog’s faeces or they may develop into a tougher more durable ‘cyst’ form, which is again passed in the dogs faeces but is able to survive for long periods in the external environment. Dogs are infected by ingesting the cysts from contaminated water and the environment. Infected dogs may not show any clinical signs of Gardiasis, but they can still shed the protozoa from their systems, spreading the infection to other healthy animals. Infection and subsequent illness is more commonly seen in younger animals. Signs of infection include: chronic or intermittent diarrhoea that may appear ‘fatty’ and slimy, accompanied by a very foul smell. Weight loss is also possible if left untreated.