What is Seasonal Canine Illness (SCI)
Seasonal Canine Illness (SCI) is a rare but serious condition that can affect dogs of any age or breed, typically during the autumn months (August–November). It develops quickly and can be life-threatening, with symptoms sometimes worsening within hours.
The exact cause of SCI is unknown. Some dogs affected have recently walked in woodland areas, and there is ongoing concern about harvest mites, although other theories such as algae exposure or agricultural chemicals have been suggested.
Written by Dr. Mariella Roberts, Veterinary Surgeon, Animal Trust Vets CIC | Published October 2025 | Review date October 2028 | This advice is for UK pets only and is not a replacement for seeing a vet
Symptoms of Seasonal Canine Illness (SCI)
Diarrhoea
Weakness or low energy
Abdominal pain
Fever (high body temperature)
Muscle tremors
Severe dehydration
When to contact your vet
If you notice any of the symptoms above, make an appointment to see your vet.
Diagnosis of Seasonal Canine Illness (SCI)
A thorough history and clinical examination
Tests are not specific to SCI but may include blood, urine, and stool tests
Treatment for Seasonal Canine Illness (SCI)
Early treatment is crucial, and this may include:
Fluid therapy (drip to maintain hydration)
Anti-sickness medication
Pain relief
Occasionally, antibiotics if a secondary infection is suspected
Prevention of Seasonal Canine Illness (SCI)
Minimise woodland walks in the autumn, and keep dogs on a lead
Use veterinary-prescribed sprays on feet and legs to prevent harvest mites
Wipe your dog’s feet and legs after walks
Outlook
With early and intensive veterinary care, most dogs recover well. However, SCI can progress rapidly and be fatal if left untreated. Immediate veterinary attention is essential if symptoms appear.