Dog roundworms – what owners need to know
DOG worms are one of life’s less pleasant topics, but they do need to be discussed. Every dog owner should be aware of them, and should take steps to ensure that their pet – and their human family – are protected from these slimy, wriggly parasites.
There’s a wide range of dog worms, from the classical dog roundworm (Toxocara Canis), to tapeworms, hookworms, whipworms, lung worms and heart worms. Most of the time, dog worms go unnoticed: they hide inside the dog’s body, without causing any visible signs of a problem. But from time to time, unpleasant symptoms can develop, and rarely, serious or even fatal illness can follow.
It’s funny how age-old myths about pet health can sometimes stay around, long after they are no longer true. There’s a commonly held belief that when a dog rubs its bottom along the ground (so-called sledging or scooting), the most likely cause is worms. This belief is linked to the fact that the common worms that affect children (pinworms, or threadworms), often cause intense itchiness in this area, due to the fact that the female worms lay their eggs around the anus. In fact, dog worms rarely cause this type of itchiness, and there are dozens of other common causes of sledging. Examples include impacted or infected anal sacs, and allergies (to food, or to something in the environment).
People often also believe that when their child has worms, the dog must somehow be implicated. Again, this is a mixed up view of what’s really going on. Dogs cannot be infected with the human pinworm or threadworm, and they cannot pass it on to humans.
The reason why people believe this is because they have heard that dog worms can infect children, but it’s important to understand the truth behind this. The common dog worm, Toxocara canis, can indeed be passed on to humans. A healthy adult human’s immune system can deal effectively with the challenge, stopping the worms from moving into the adult’s body from the intestines. Children don’t have such effective immune defences, and if children swallow infective worm eggs, the worm larvae are likely to move through the intestinal wall, into the bloodstream and around the body. Even when this happens, most often the worms will settle into a tiny cyst somewhere harmless (such as in the muscles) and there won’t be a problem. ,often migrate through the child’s tissues. If a larvae ends up in the brain or eye of a child, there can be very serious consequences including seizures or blindness. It’s very rare for this to happen, but this risk is the reason why it’s so important to make sure that dogs are wormed regularly.
How often should dogs be given a worm dose? Typically, a puppy should be wormed every two weeks from two weeks to twelve weeks of age, once a month until six months of age, then every three months for the rest of its adult life. A good quality, broad spectrum wormer should be used. It’s best to talk to your vet about individualised dosing regimes: sometimes there are other issues that need to be considered apart from the common roundworm. For example, dogs that eat slugs and snails need to have regular lungworm dosing,and this can be combined in the same medication.
Studies have shown that around 25% of dogs are infected with Toxocara Canis, with older dogs being less likely to carry worms, and stray or neglected dogs carrying higher burdens. Often there are no visible signs of worms: this lack of any obvious signs of worms in dogs is the main reason why vets recommend routine de-worming, even when animals appear to be in full health.
It’s important to understand that although children can get worms from dogs, this doesn’t happen directly. Dog worm eggs only become dangerous to humans after the dog faeces has been incubating in the environment for a few weeks, giving the eggs time to mature to the infective stage. So rather than dogs being the risk, the problem is “old dog faeces”. This is why it’s so important for pet owners to pick up after their pets. In particular, it’s critically important that areas frequented by children are effectively protected from old dog faeces.
As well as treating dogs for worms, it makes sense to take steps to minimise any risk of children ingesting dog worm eggs from the environment. This is why it’s so important to remove faeces from any environment that is frequented by children (e.g. poop scooping in gardens and public places) and why hygiene measures are essential (e.g. hand washing before meals) in order to reduce the risk of worm infection. Worm eggs can survive for many years in the environment which is why it’s so important to prevent them from getting there in the first place (by worming dogs regularly and picking up poops. Historical studies of soil samples, before poop-scooping was commonplace, used to show that between 15 to 78% of soil samples from parks and playgrounds were positive for worm eggs. This figure is likely to have improved significantly now, because most people are aware of the need to pick up after dogs, but it’s a reminder of the potential risk.
Dog worms have been around for centuries, but at least now, with modern medication, they can be easily controlled.