Vital information

What is seasonal canine illness?

Seasonal canine illness is a little-known condition that typically affects dogs in the autumn. Symptoms usually appear in dogs between one and three days after being walked in a wooded area. This condition, also called canine seasonal disease, is fast acting and potentially fatal, with symptoms often becoming severe within a matter of hours.

What to do if your dog is showing signs of seasonal canine illness?

Seasonal canine illness is life-threatening. Untreated, it can quickly lead to dehydration and death. You should contact your vet, or out of hours your nearest Vets Now, straight away if your dog or puppy is showing signs of this illness — particularly if it’s within three days of them roaming in woodland.

An image of a dog looking sick for Vets Now article on Seasonal Canine Illness
Seasonal canine illness can be life threatening if left untreated
Main symptoms

Seasonal canine illness symptoms

The main symptom of canine seasonal disease is vomiting, although this is often accompanied by diarrhoea and lethargy. Dogs with SCI may also show signs of abdominal pain, fever and muscular tremors. Bear in mind that these are also typical symptoms of gastrointestinal upsets and other conditions so don’t be misled into thinking your dog has simply eaten something unpleasant.

Symptoms of seasonal canine illness

An image of a dog laying down in a field next to a wild mushroom for Vets Now article on canine seasonal illness
Theories for canine seasonal illness have ranged from allergic reactions to mushrooms, algae and agricultural chemicals to infections from harvest mites
Causes & treatment

What causes seasonal canine illness in dogs?

The cause of SCI in dogs has been the subject of vigorous debate and research, but it remains unknown. Theories have ranged from allergic reactions to mushrooms, algae or agricultural chemicals to infections from harvest mites. The mushroom theory has now been discounted although there are still concerns over harvest mites. The reason for this is many of the dogs struck down by SCI have been infested with the tiny insects.

How is SCI in dogs diagnosed?

It can be difficult for vets to make a definitive diagnosis of SCI. This is partly because so little is known about the condition and partly because the symptoms of the disease are so similar to many other conditions affecting dogs. If your dog is hospitalised, they may be given intravenous fluid therapy (placed on a drip) and prescribed anti-sickness medicine and, in rare cases, antimicrobials. It’s likely your vet will also take steps to rule out other causes. This may involve carrying out tests including x-rays, ultrasound, a biochemistry panel and taking blood, urine and faecal samples. If harvest mites are present then your vet may also prescribe treatment to destroy them.

Image of Vets Now vet and vet nurse treating a dog with seasonal canine illness symptoms
If caught early, seasonal canine illness can be treated effectively

More on this topic

Prevention & prognosis

How to prevent SCI in dogs

The underlying cause of SCI remains unknown so prevention advice is limited to being vigilant and using a lead during woodland walks, keeping your dog well hydrated, closely monitoring your dog for mites, and raising awareness of SCI by telling others about the disease. If you’re concerned contact your vet straight away or, if it’s out of hours, your nearest Vets Now pet emergency service.

SCI survival rate

According to the Animal Health Trust, which has led the way in research into SCI, the prognosis is good for dogs treated early and appropriately. In 2010, when SCI was first reported, 20% of the cases recorded died. Two years later fewer than 2% died. Most dogs given intensive veterinary care recovered within seven to 10 days.

Seasonal canine illness locations

The first case of SCI was reported in 2010 after dogs had been walked in woodland in the Sandringham estate in Norfolk. Since then cases appear to have been concentrated in East Anglia, Nottinghamshire, Lincolnshire and Warwickshire, although there have been reports from further afield. They are generally seen from August onwards, with a peak in September and tailing off into November.