By Dial A Vet Veterinary Team
Last updated: 2 November 2026
Toxoplasmosis is a parasite infection that most dogs carry without ever showing a sign. The problem is the minority that do get sick. In a young puppy, or in an adult dog whose immune system is already under pressure, the same parasite can spread through the lungs, liver, muscles and brain and cause a serious illness. Knowing which dogs are at risk, and which signs need a vet the same day, makes a real difference.
Key takeaways
- Toxoplasmosis is caused by Toxoplasma gondii, a single-celled parasite that can infect almost any warm-blooded animal, including people.
- Cats are the only animals in which the parasite completes its life cycle. Dogs pick it up mainly from raw or undercooked meat, prey animals, contaminated soil, or cat faeces.
- Healthy adult dogs usually control the infection and show no signs.
- Puppies and dogs with weakened immune systems can develop fever, diarrhoea, coughing, breathing trouble, jaundice and seizures.
- Many dogs never need treatment. Sick dogs are treated by a vet, sometimes in hospital.
- Cooking meat properly and keeping dogs out of the litter tray are the most useful prevention steps.
How dogs catch Toxoplasma
The Merck Veterinary Manual explains that wild and domestic cats are the only true hosts of Toxoplasma, meaning the parasite needs a cat to complete its life cycle. Infected cats shed microscopic eggs in their faeces, and those eggs end up in litter trays, garden beds and soil.
Dogs are exposed in a few everyday ways:
- Eating raw or undercooked meat that contains dormant parasite cysts
- Catching and eating rodents, birds or other small animals
- Raiding the cat's litter tray, which many dogs find irresistible
- Sniffing and licking soil in gardens where cats toilet
Once a dog swallows the parasite, it can spread through the body. In most healthy adults the immune system walls it off, and the dog carries a dormant infection with no illness at all.
Which dogs get sick
Merck notes that serious disease is mainly seen in two groups:
- Puppies. Their immune systems are still developing, so the parasite can spread widely.
- Adult dogs with weakened immunity. This includes dogs with other serious illnesses and dogs on medicines that suppress the immune system. These dogs are at high risk of severe, sudden disease.
Signs of toxoplasmosis in dogs
Signs depend on where the parasite settles. Merck lists fever, diarrhoea, coughing, breathing difficulty, yellowing of the skin and eyes (jaundice) and seizures in puppies, and the disease can be fatal. You may also notice:
- Lethargy and poor appetite
- Weakness, wobbliness or stiff, painful muscles
- Tremors or other changes in behaviour
None of these signs are specific. Many other infections and diseases look the same, including neosporosis, a related parasite that was confused with toxoplasmosis for years before it was identified as a separate disease. That is why testing matters.
When to see a vet
Book a vet visit within a day if your dog:
- Has a fever, has gone off food or is unusually flat for more than a day
- Has ongoing diarrhoea, especially a puppy
- Has a cough or seems to tire quickly on walks
Go to an emergency vet now if your dog:
- Is struggling to breathe or breathing with an open mouth at rest
- Has a seizure, or seems confused, unsteady or unable to stand
- Has yellow gums or eyes
- Is a young puppy that is weak, cold or not feeding
How vets diagnose it
Your vet will start with a full history, including diet (raw feeding matters here), hunting habits and whether there is a cat at home. A physical exam is usually followed by blood and urine tests to check organ function and look for clues of infection.
Antibody blood tests can show that a dog has been exposed to Toxoplasma, but because so many healthy dogs carry the parasite, a positive result does not prove it is causing the current illness. Vets interpret the results alongside the signs, and may also test for Neospora because the two can look so alike. Dogs with neurological signs may need further work-up at a referral hospital.
Treatment and outlook
Merck notes that in many cases no treatment is needed. When a dog is unwell, your vet may prescribe an antibiotic that acts against the parasite. Dogs with seizures need medicine to control them, and very sick or dehydrated dogs may be hospitalised for intravenous fluids and supportive care.
The outlook depends on which organs are affected and how quickly treatment starts. Dogs with mild disease often recover well. Puppies with widespread infection, and dogs with severe lung or brain involvement, have a more guarded outlook. Treatment controls the active parasite but does not always clear dormant cysts, so your vet may talk about monitoring for relapse if your dog's immune system is weakened again later.
Prevention
- Feed commercial dog food or thoroughly cooked meat. Merck notes that cooking meat to at least 67°C, or freezing it, kills the parasite.
- Be aware that raw diets carry this risk. If you choose to feed raw, discuss safe sourcing and handling with your vet.
- Put the litter tray somewhere your dog cannot reach, and scoop it daily.
- Discourage hunting and scavenging on walks.
- Wash your hands, chopping boards and knives after handling raw meat.
Is my dog a risk to my family?
Dogs do not complete the parasite's life cycle, so they are not the main way people catch toxoplasmosis. Healthdirect notes that people usually catch it from cats and their faeces, and that it is also found in other animals and soil. Undercooked meat, unwashed vegetables and gardening without washing hands are common routes.
If you are pregnant, toxoplasmosis can harm your baby, so it is worth talking to your doctor or midwife about your own risk. Simple steps help: have someone else scoop the litter, wear gloves in the garden, and wash your hands after handling raw meat or soil.
FAQ
Can my dog catch toxoplasmosis from my cat?
Indirectly, yes. Dogs that eat cat faeces from the litter tray or garden can swallow the parasite's eggs. Keeping the tray out of reach and scooping it daily lowers the risk.
Is toxoplasmosis in dogs contagious to other dogs?
It does not spread from dog to dog by normal contact. Dogs catch it from contaminated meat, prey, soil or cat faeces.
Should I stop feeding raw meat?
Raw meat is one of the main sources of infection. Talk with your vet about whether a raw diet suits your dog, especially if you have a puppy, a dog with a weak immune system, or a pregnant person in the house.
Can toxoplasmosis come back?
The parasite can stay dormant in the body. If the immune system is later weakened, it can reactivate, which is why vets watch high-risk dogs closely.
Talk with a vet
If your dog is off colour and you are not sure how urgent it is, Dial A Vet's real vets and vet nurses can talk it through with you on a video consult, help you decide whether your dog needs to be seen in person today, and explain which tests your local vet may suggest. Dial A Vet consults cover dogs and cats. For breathing trouble or seizures, go straight to your nearest emergency vet. Related reading: toxoplasmosis in cats and neosporosis in dogs. Book a video consult with Dial A Vet.
References
- Merck Veterinary Manual. Toxoplasmosis in Dogs.
- Merck Veterinary Manual. Neosporosis in Dogs.
- VCA Animal Hospitals. Toxoplasmosis.
- Healthdirect Australia. Toxoplasmosis.
Disclaimer: Educational only. This page does not replace an examination or advice from your own veterinarian. If you are worried about your pet right now, contact your local vet or nearest emergency animal hospital.