What Is Neosporosis?
Neosporosis is an infection caused by Neospora caninum, a single-celled parasite closely related to the organism behind toxoplasmosis. Dogs are the main host: the parasite completes its life cycle in the dog’s gut, and cattle are the most important intermediate host. For years, many cases in dogs were mistaken for toxoplasmosis until Neospora was identified as a separate parasite in the late 1980s.
Most infected adult dogs never show signs. The disease matters most in young puppies infected before birth, where the parasite attacks nerves and muscles and can cause progressive, sometimes permanent, hind-leg paralysis.
Why it matters
A puppy whose back legs slowly stiffen and straighten is often assumed to have an injury. Early testing and treatment give the best chance of keeping mobility.
How Dogs Get Infected
- Before birth: an infected mother can pass the parasite to her puppies across the placenta, and she may do so in more than one litter.
- Eating infected tissue: raw beef, offal, placentas, or aborted calves can carry tissue cysts. This is one reason vets caution about raw dog food and farm access.
- Contaminated soil or water: less commonly, from eggs shed in another dog’s feces.
Signs Owners Notice
- In puppies, usually from about 3 to 9 weeks old: weakness in the back legs that progresses to rigid, straight hind legs
- Muscle wasting, difficulty walking, or a puppy that drags its rear
- Trouble swallowing or a weak jaw in more advanced cases
- In adult dogs: incoordination, seizures, muscle pain, skin sores, cough, or heart problems
Diagnosis
Your vet will combine the neurological exam with blood tests for antibodies to Neospora, and sometimes PCR testing, a muscle biopsy, or spinal fluid analysis. Other causes of weakness have to be ruled out, including coonhound paralysis, myasthenia gravis, toxoplasmosis, distemper, and orthopedic problems that cause limping. Littermates are often tested too, because several puppies in one litter can be affected.
Treatment and Outlook
- Antiprotozoal medicine: clindamycin, trimethoprim-sulfonamide, or similar drugs, often for at least four weeks.
- Physical therapy: range-of-motion work and supported walking help limit muscle contracture.
- Supportive care: padded bedding, help with eating, and keeping the puppy clean if it cannot stand.
Puppies treated before their legs become rigid have the best chance of recovery. Once severe contracture develops, the outlook is guarded and some damage may be permanent. Adult dogs with milder disease often respond well to treatment.
Practical Tips for US Pet Owners
- Avoid feeding raw beef or offal, and keep dogs away from calving areas and livestock carcasses.
- Talk to your vet before breeding a female that has had an affected litter, since she may pass the infection again.
- Pick up dog feces promptly, especially on farms where cattle graze.
- Find a nearby practice through veterinary clinic listings.
When to see a vet
Book a visit right away if a young puppy shows weak, stiff, or straightening back legs, or if an adult dog suddenly becomes wobbly or starts having seizures.
Key Takeaways
- Neosporosis is caused by the parasite Neospora caninum, with dogs as the main host.
- Puppies infected before birth are at greatest risk of hind-leg paralysis.
- Early treatment improves the outlook; raw beef and farm exposure are key risks.
FAQ
Can people catch neosporosis from dogs?
There is no confirmed human disease caused by Neospora caninum. Good hygiene around dog feces is still sensible.
Is neosporosis the same as toxoplasmosis?
No. The parasites are related, but cats are the main host for Toxoplasma while dogs are the main host for Neospora.
Can cats get neosporosis?
Natural disease in cats is very rare. It is mainly a problem in dogs and cattle.