Why Is My Dog Sick After Walking in Woodland? Seasonal Canine Illness Facts

Updated on October 2, 2019
Sophie Jackson profile image

Sophie Jackson is a dog lover and trainer living in the UK. She competes in agility and obedience with her four dogs.

The first cases of Seasonal Canine Illness were in dogs who had been walked at the royal Sandringham estate
The first cases of Seasonal Canine Illness were in dogs who had been walked at the royal Sandringham estate | Source

Seasonal Canine Illness: The Mystery Killer

Seasonal Canine Illness (SCI) is a mysterious disease that first appeared in 2009 on the Sandringham Estate. While Sandringham is owned by the royal family, the woodlands are open to the public and many people walk their dogs there. In the autumn of 2009, several dogs became sick after walking at Sandringham without there being any obvious cause. Some dogs did not recover from the unknown illness.

With the arrival of winter, the cases of sickness disappeared, and through the spring and summer, everything appeared fine. However, in the Autumn of 2010, the mysterious illness returned. By now there was concern that a new disease had emerged within the UK dog population. Due to the restrictive period in which the illness was noticed, it became known as Seasonal Canine Illness.

Though initially the disease was only seen around Sandringham, within the next few years, similar cases were being reported across the country and it seemed that whatever was behind the sickness was rapidly spreading.

In 2010, the Animal Health Trust, a charitable organisation that aims to help animals live healthier and happier lives through research into disease, began investigating SCI. Currently, the research is ongoing and no definitive explanation for the condition or why it affects some dogs and not others has been put forward.

The lack of knowledge surrounding SCI has turned it into a monster in the minds of dog lovers—how can you keep your pet safe from a disease that you know nothing about? Fortunately, there are some things we do know for sure about SCI and this gives us a way to protect our dogs, even if we are not certain about the causes of the sickness.

Cases of SCI have been linked to dogs being walked in woodland
Cases of SCI have been linked to dogs being walked in woodland | Source

What Is SCI?

Seasonal Canine Illness has a vague set of symptoms which can be mistaken for other diseases. Dogs develop vomiting and diarrhea, which might be mistaken for a simple tummy bug. What marks SCI out is the extreme lethargy dogs experience, along with acute abdominal pain. Some dogs become extremely nauseated, and they may have a high temperature or muscle tremors. A dog suffering from SCI will appear almost in a state of collapse, weak and unwilling to move, along with being hunched up through abdominal pain.

If left untreated, dogs can become dehydrated and in severe cases, the illness can be fatal. However, with prompt medical treatment, which usually involves putting the dog on a drip, administering anti-sickness medicines and sometimes antibiotics, most dogs recover.

According to First Aid for Pets (which offers veterinary-approved courses in first aid for animals) the majority of dogs that contract SCI and receive treatment recover within 7-10 days. As of 2012, only 2% of dogs with SCI have died from the condition. This is believed to be due to better awareness of SCI among vets and owners. In contrast, when the disease was first noticed in 2009/2010, 20% of affected dogs died.

One of the key factors of diagnosing SCI is understanding that the disease will manifest within 24–72 hours after a dog has been walked in woodland. If your dog exhibits the symptoms above and has been in woodland within the last three days, there is a good chance they have SCI and will need immediate veterinary treatment.

Another important point is that SCI only appears at certain times of the year (hence the 'seasonal' part of the name). Cases are typically seen between August and November. There is a clear time pattern for the disease and also a specific location where it is contracted suggests an environmental element to the condition. Something appears in woodlands during the autumn that triggers this illness in dogs, the real question remains—what could that 'something' be?

SCI occurs during the late summer and autumn
SCI occurs during the late summer and autumn | Source

What Is the Risk of My Dog Catching SCI?

Though SCI is an unpleasant condition, it needs to be remembered that it is quite rare and; according to the Blue Cross, the number of reported cases of the illness have declined since it was first recognised in 2010. Equally, with better understanding, the number of fatal cases of SCI have significantly decreased.

The disease can strike a dog of any age, gender, size or breed, and there is no obvious group or types of dogs (ie. puppies) that are more at risk. Numerous dogs can be walked over the same piece of woodland and only one or two become sick. Whether the affected dogs are somehow predisposed to the disease, or whether non-affected dogs have a natural immunity is another open question.

Many people choose to avoid walking in woodland between August to November, though the Animal Health Trust states: "We would never want to say to people 'do not go to the woods' because the percentage of dogs that get ill is small."

During the prime SCI period, many working dogs will be found in woodland, including on the Sandringham estate as the shooting season begins. Cases of SCI among these dogs are limited and there has been speculation that dogs that are regularly walked in woodland develop a resistance to whatever causes SCI. Though, again, the evidence for this is unclear.

The important thing to bear in mind is that:

  1. SCI is rare.
  2. If you can avoid woodland walks between August and November you will likely never encounter the disease.
  3. Even if SCI strikes, the majority of dogs survive it.

Harvest Mites, also known as Chiggers, have been blamed for SCI
Harvest Mites, also known as Chiggers, have been blamed for SCI | Source

What Is Being Done to Stop SCI?

With growing awareness of SCI, many dog owners are asking what is being done to stop the disease spreading, and what research is happening concerning the illness? When the Animal Health Trust began investigating SCI in 2010 there were a variety of theories about the cause of the sickness, including that fungal spores or blue-green algae might be the trigger.

These were eventually ruled out and, in 2013, the AHT began a pilot study investigating whether harvest mites could be the key. Several of the dogs suffering from SCI were also found to have harvest mites and, as these are seasonal creatures active at the same time as SCI cases appear, there might be a link.

Harvest mites are tiny, red critters that eat the skin cells of animals, including humans. They go through four life stages—egg, larva, nymph and adult. Only while in the larval stage do the mites feed on animals. They are commonly found in woodland, but can also be found in gardens, parks and other grassy areas. When the mite attaches to a dog, it begins to eat a hole as it munches up skin cells. This causes acute irritation and many dogs become very itchy in the late summer and autumn from harvest mite bites.

Unlucky dogs can suffer from severe infestations, with swarms of mites covering their skin, especially on the chest, armpits, tummy and around the genitals. The mites look like tiny red or orange dots, but more often people notice the damage they have caused rather than the parasite, with the dog's skin developing nasty red welts.

Harvest mites in the UK were not considered disease carriers, until the recent SCI outbreaks. However, in East Asia, a type of mite from the same family as the UK's harvest mite is known to carry a disease called Scrub Typhus, which affects humans and presents with the symptoms of fever, headache, muscle pain, cough and gastrointestinal problems. Which is curiously similar to the symptoms of SCI in dogs. Could the UK harvest mite have become a carrier for a similar disease to Scrub Typhus that only affects dogs?

Research remains ongoing to prove conclusively that harvest mites are to blame, in the meantime, one suggested way to protect dogs is to use a fipronil-based parasite treatment. Castle Vets of Reading provides this information:

"There is no official licenced preventative treatment for harvest mites in the UK but Fipronil spray treats some other mites effectively and is thought to have an effect on the harvest mite. Fipronil spray is a prescription medication that is available from most veterinary practices (alternatively you can ask your vet for a prescription so that you may buy it elsewhere)."

Until such a time as the full causes and details of SCI are understood, the most important thing is to be vigilant, avoid woodland if possible between August and November and to always seek veterinary advice when your pet becomes unwell.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.


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