Seasonal canine illness (SCI) Seasonal canine illness (canine seasonal disease) is a relatively rare condition that typically affects dogs in the autumn. This condition has a rapid onset and is potentially fatal; symptoms often become severe within a matter of hours. If left untreated, it can quickly lead to dehydration and death. You should contact your vet or FirstVet straight away if your dog or puppy is showing signs of this illness, especially if it is within three days of roaming in woodland. Are you concerned about your pet? Meet a vet online!Included free as part of many pet insurance policiesHelp, treatment and if you need it, a referral to your local vetOpen 24/7, 365 days a year Book an appointment The first case of SCI was reported in 2010 after the dog had been walked in woodland on the Sandringham Estate in Norfolk. However, it had been recognised by vets in other areas prior to this date but wasn’t classified as a separate disease until 2010. Cases tend to be concentrated in and around woodland. The disease has been diagnosed in the following regions: East Anglia, Nottinghamshire, Lincolnshire and Warwickshire, although there have been reports from further afield. It is generally seen from August onwards, with a peak in September that tails off into November.Signs of seasonal canine illnessSigns usually appear in dogs following a walk in a wooded area. The signs are non-specific so the condition may be missed. If your dog is vomiting or lethargic after recently being exercised in woodland then contact your vet immediately. Symptoms to look out for include:VomitingDiarrhoeaLethargyAbdominal painFeverMuscular tremorsCauses of seasonal canine illnessThe cause of SCI is currently unknown. There are many theories about the cause of SCI, from allergic reactions to mushrooms, algae, agricultural chemicals and infection from harvest mites. The mushroom theory has now been discounted, however there are still concerns over harvest mites as some of the dogs that have contracted SCI have been infested with them.Harvest mites are tiny orange insects found in long grasses in the late summer and autumn. They climb up the grass and jump onto passing mammals including humans, cats, dogs and rabbits. Harvest mites feed for two to three days on thin areas of skin such as in front of the ears, at the base of the ear flap or between the toes (although they can also found on the stomach, armpits, chin and lips). The bites are very itchy and can cause a considerable amount of discomfort. Harvest mites can be seen by the naked eye as very small orange dots.What you can do yourselfUse a lead during woodland walksKeep your dog well hydrated after a walkCheck your dog regularly for harvest mitesBe vigilant for symptoms of SCI in the days following woodland walksIf your dog is vomiting then make an appointment with either your own vet or FirstVet to discuss thisTreatment of seasonal canine illnessIt can be difficult to make a definitive diagnosis of SCI because very little is known about the disease and the symptoms are similar to many other common conditions that affect dogs. If your dog requires hospitalisation they may be given intravenous fluids and prescribed anti-nausea medication. Occasionally, antibiotics are given. It is likely that your vet will want to rule out other more common diseases as a precaution. This may involve tests such as x-rays, an ultrasound scan, and blood, urine and stool analysis. If harvest mites are present then your vet may also prescribe treatment to eliminate them.When to see your physical veterinarianIf your pet has recently been walked in woodland and you notice any of the above signsTo discuss anti-parasite treatments that protect against harvest mitesIf you have any concerns about seasonal canine illness, book a video appointment to have a chat with one of our FirstVet vets.