For many of us, our dogs and cats are important members of the family and they enhance our quality of life.  However as well as all the benefits of pet ownership, there are a few health risks.  This article describes a few of the diseases you could catch from your dog or cat.

To get things in perspective, the risk of picking up a disease from your pet is probably less than the risk of picking up a disease from another person.  People spread many of the most common diseases such as colds, flu, chicken pox, measles, hepatitis even AIDS, and pets don't!  However, there are some significant diseases that can be spread by dogs and cats.  If you know about them and take a few common sense precautions, the chances of catching a disease from your pet are minimal.

Diseases that can spread from animals to people are called zoonoses.  Here are some of the most common dog and cat zoonoses in our part of the world:

Dogs:  Roundworm infections, ringworm, and mange
Cats:  Ringworm, cat-scratch disease, and toxoplasmosis


If dogs are not given worm treatments (and this especially applies to puppies), they may have Toxocara roundworms in their stomach and intestine, and they will pass worm eggs in their faeces (or poo!).  It takes only a tiny amount of this poo to transmit worms to a person or another dog if it's inadvertently eaten!  Usually, this doesn't cause any problems but in very rare cases, after the developing worms have been taken into the mouth they travel around the body trying to find the gut.  As they do this they can cause inflammation in the organs they pass through, causing symptoms like vision disturbance, fever, and coughing.  Therefore it's important to have your dogs and especially puppies wormed regularly as directed by your vet, and it's very important to make sure you don't put your hands near your mouth or onto food after handling them.

(Note that the Toxocara worm is different from the threadworm that is so common in children, although they are both roundworms.)

Other types of worms can cause other types of problems.  Some types penetrate through the skin, most commonly the soles of the feet, causing irritation of the skin and sometimes other symptoms such as abdominal pain and diarrhea to fever, weakness, loss of appetite, and anaemia.  Fortunately, this seems to be rare in New Zealand.

Ringworm and mange

There are some skin diseases that can be shared between humans and dogs and cats.  The most common are mange and ringworm.  Mange is caused by tiny mites in the skin and ringworm by fungal infections.  In cats and dogs, both diseases cause patches of scaliness and hair loss that can be itchy, and both diseases should be treated by your vet using appropriate skin preparations and medications given by mouth or by injection.

Cat scratch disease

A cat scratch or bite can sometimes cause a nasty skin infection.  This is not usually serious but it can result in swollen lymph glands and even mild flu-like illness.

The bacteria that cause the infection (Bartonella henselae) can be found in cats' saliva and can be spread anywhere on their bodies by licking.  The bacteria are passed from cat to cat by fleas.  Some people acquire the infection by infected saliva getting into an existing cut.

The condition seems to be more commonly transmitted through the scratches of young cats, and the skin infections they cause are more common in young people (under 21 yrs old).  The rare cases in which the skin infections become serious can be treated with antibiotics.

Signs to look out for include:

  • a cat bite or scratch that doesn't heal in the usual time
  • a red area around the cat bite or scratch that continues to get bigger three days or more after the injury
  • a sore that develops around the area of a cat bite or scratch three to 10 days after it has happened
  • fever, headache, swollen lymph glands near the bite or scratch

To prevent these skin infections:

  • People especially children shouldn't invite scratches by teasing or provoking cats and kittens
  • Don't let cats lick any open cuts
  • Wash hands after stroking cats
  • Wash any cat scratches or bites thoroughly with soap and running water
  • Use flea treatments as necessary to prevent flea infestations in cats and kittens.


For a short time in their lives, some cats can spread a disease called toxoplasmosis.  This is caused by a tiny parasite and it is spread to humans through contact with cat poo.  Some cats pick up the disease from rats and mice when they first begin to hunt, and then they excrete Toxoplasma eggs for a few weeks.  After that, they are immune to the disease and they don't excrete the eggs.

Fortunately, human toxoplasmosis is rare, but when it does occur it is usually in a child who has played in and even eaten soil contaminated with cat poo.   Also at risk are pregnant women, because the infection can spread to the baby in their womb.  The baby may be born with brain or eye damage, or symptoms may not develop for several years.


At one time there were real health risks associated with dogs shedding hydatid tapeworm eggs, which could cause hydatid cysts in people.  This is no longer a risk because hydatids disease has been eliminated from New Zealand.


As a pet owner you can minimize the risk of zoonotic disease in your family:

  • Give your dog and cat worm treatments regularly as directed by your vet (the frequency of worming will depend on the age of your pet but should be much more frequent for puppies)
  • Give your dog and cat regular flea treatments
  • Practice good hygiene and encourage children to wash hands regularly, especially after playing in dirt or sandpits
  • Promptly dispose of dog and cat poos
  • Pregnant women should not empty cat dirt trays
  • Keep children from playing in soil or sandpits that might be contaminated
  • Cover sandpits when not in use
  • Keep your dog's environment clean, especially its bedding
  • Wear gloves when gardening
  • Get veterinary treatment for any pet that falls ill or develops skin problems