Can you clear up a sisterly squabble for me?!
My sister thinks I shouldn't let my dog lick my face as I will catch something and if she licks my eye I will get that disease that makes you blind. We both grew up with dogs as kids and must have had every inch of our faces licked and neither of us ever got ill.
Please can you tell us the facts? (Though I bet I'm right!)
Susie Morris, Birmingham
Alison Logan, Vet, advises...
There are, I am afraid, elements of truth in your sister’s assertion.
I think that she is thinking of ocular larva migrans when she talks about you running the risk of going blind, but it is not contracted directly across the eye from a dog’s tongue. This is a rare complication of migrating Toxocara canis larvae within the body reaching the eyes.
If a dog has an active roundworm Toxocara canis burden, he or she will be passing T canis eggs in his or her faeces. These eggs are invisible to the naked eye, which is why routine preventative treatment for roundworms is recommended. After a few days in the environment, the eggs mature and became infective – if they are then accidentally swallowed by a person, larvae develop and can migrate through tissues, causing an inflammatory reaction. In rare cases, organs such as the liver or lungs may be damaged, and the larvae can affect vision or even cause blindness if they reach the eyes.
Simple personal hygiene measures such as washing your hands before eating greatly reduce the chances of accidentally ingesting roundworm eggs. This is why children are generally more at risk than adults. Visceral and ocular larva migrans are rare, but obviously to be avoided as the effects can be devastating.
So, with roundworm eggs needing to spend time maturing in the environment before they are infective, there should be no problem with your dog wiping your face with her loo paper. Yes, you did read that right! Whereas you and I drop soiled loo paper after use into the loo to be flushed away, your dog’s loo paper is her tongue. Therefore … well, need I say more? This is why we are taught to wash our hands after stroking our dogs, and other pets, before eating. Dogs wash themselves all over with their tongues, and may well wash their rear before washing their coat, or your face. Faeces, dog and human, are a potential source of other infections. We are taught to wash our hands after using the loo for very good reasons!