Seasonal Canine Illness (SCI)

Cases of SCI have occurred in the highlighted areas.

Cases of SCI have occurred in the highlighted areas.

Seasonal canine illness (SCI) is a potentially life threatening syndrome seen in dogs that have been walked in woodlands in the 3 days prior to falling ill.

SCI was first identified in 2009 at the Sandringham Estate in Norfolk and around the same time, cases were also identified in Thetford Forest (Norfolk), Sherwood Forest and Clumber Park (Nottinghamshire), and Rendlesham Forest (Suffolk). The disease is called seasonal canine illness as most cases are seen between August and November, with a peak in September. The Animal Health Trust in Newmarket is currently conducting research to identify the cause of SCI through a Kennel Club Charitable Trust funded investigation.

What causes SCI?

The cause of SCI is not known. Many cases of dogs with SCI have been found to have harvest mites, and this potential link is currently being investigated further. Although harvest mites are not known to transmit disease in the UK, similar mites are known to do so in other countries. So far, the Animal Health Trust investigation has identified potential risk factors which may increase the likelihood of a dog getting SCI. Small dogs that are on holiday with their owner, and run out of sight through the undergrowth appear to be at increased risk of becoming ill.

How do dogs with SCI present?

Fig 2

Dogs present with sudden onset vomiting and diarrhoea within 72 hours of walking in woodland. Many dogs with SCI are lethargic (tired) and withdrawn and they may appear uncomfortable. Several cases have been noted to have a rash, particularly on their legs and belly.

If you suspect that your dog may have SCI then it is important to seek veterinary advice.

How is SCI diagnosed?

There are many potential causes of vomiting and diarrhoea in dogs, therefore it is difficult to be sure of a diagnosis of SCI.

Your vet will make a diagnosis of SCI is based on:

  • a suspicious history (walking in affected areas between August and November)
  • compatible signs (vomiting and/or diarrhoea)
  • ruling out other diseases that may appear similar

It is important that other diseases are fully considered as some toxins, infections, hormonal problems or even cancers may look similar to SCI on first appearance.

Harvest mites (orange) within the haircoat of a dog

Harvest mites (orange) within the haircoat of a dog

As mentioned above, there is a possible link between harvest mites and SCI that is currently being investigated. If a dog is suspected of having SCI it should be carefully examined for harvest mites, particularly between the toes and around the ears.

Can SCI be treated?

Just as the diagnosis of SCI is challenging, the lack of a known cause makes it difficult to treat. Many dogs with SCI require hospitalisation so that they can receive intravenous fluids. Additionally dogs with SCI are routinely treated with anti-sickness medications, antacids and sometimes antibiotics. Many of these treatments help with the other conditions that mimic SCI and so they can be used while waiting for test results or if the diagnosis is uncertain. In milder cases of vomiting and diarrhoea, hospitalisation and antibiotics may not be of benefit but this is a difficult judgement that is best made after a thorough examination by a veterinary surgeon.

Given the possible link between harvest mites and SCI, treatment of mites is recommended. There are no treatments in the UK licenced for the treatment of harvest mites on dogs but fipronil based products treat other mites on dogs safely and this drug is thought to be effective at killing harvest mites. Sprays are preferred to the spot-on products as they reach higher concentrations between the toes where the mites live. Fipronil sprays are prescription products that should only be used under specific veterinary advice.

What is the prognosis?

SCI is a potentially life threatening disease. In 2010, when the Animal Health Trust first started its investigation, 20% of the cases identified unfortunately died. Thankfully in 2012, the last complete year with data available, that was reduced to only 2%. This appears to be because of increased awareness of SCI, highlighting that prompt recognition and veterinary attention is of the utmost importance. With prompt recognition and care, most dogs make a complete recovery and 7-10 days later they are back to their normal happy selves!

For more information, the latest updates and to see how you can help with this research visit