Dog in the woods

Seasonal Canine Illness (SCI)

Seasonal Canine Illness (SCI) is a very rare condition that affects dogs in autumn (most commonly September) who have recently walked in a woodland area. 

It affects dogs of any size, shape, age or gender. We don't currently  know what causes SCI and there is no cure, however you should still contact your vet as soon as possible if you're concerned your dog may have SCI.

What are the symptoms of SCI?

The main symptoms of SCI are usually seen within three days (72 hours) of being in a woodland area. Your dog will normally show the following behaviours:

  • vomiting
  • diarrhoea
  • tiredness
  • stomach pain
  • muscle tremors
  • high temperature

However, this rare condition is not the only reason why these symptoms may be seen. There are lots of other common causes for these symptoms.

What should I do if I suspect my dog has SCI?

SCI is rare but if you suspect that your dog is showing any symptoms contact your vet immediately, especially if it's within 72 hours of visiting a woodland area.

Is there a cure for SCI?

Due to researchers not understanding the cause of SCI, there is unfortunately no specific cure. However, some of the symptoms can be alleviated with anti-sickness medication and antibiotics. If treatment is given quickly, most dogs do recover from SCI.

How serious is SCI?

In some rare cases, SCI has been known to be very severe and sadly some dogs do not survive. But with early treatment, recovery is usually possible.

Luckily, research carried out by the Animal Health Trust suggests that there’s been a decrease in the number of fatal cases since 2010.

What can I do to reduce the risk of my dog getting SCI?

You should closely monitor your dog after they've been on a woodland walk. You can help reduce the risk of your dog getting SCI by:

  • keeping your dog hydrated
  • using preventative spray against mites before you walk your dog. Research suggests that harvest mites are commonly noted on dogs suffering with SCI, which means that using preventative spray on their paws and underside could potentially help prevent the illness.
  • if your dog is unwell please contact your vet asap and mention any woodland walks within the last few days. Visiting your vet at an early stage could be the difference between life and death.


At present there are no products licensed for treating harvest mites in dogs, but there is some evidence that Fipronil spray applied to the whole body may be effective. Always follow the manufacturer's instructions.

Page details


• 8 November 2022

Next review

• 8 November 2025

Approved by
Róisín Bolger

Veterinary Surgeon MRCVS