Dog owners are being advised of the increased risk of lungworm.
Vets4Pets has warned that cooler nights means dogs are more likely to come into contact with snails and slugs, which are the most common hosts of the parasite.
Director of clinical services Dr Huw Stacey said: “Lungworm is a parasite and has a life-cycle which starts and ends with snails and slugs.
“The lungworm larvae are found in dogs’ faeces and are eaten by molluscs, which then infect other dogs that either eat these slugs or snails, or come into contact with their slime.”
Symptoms can include changes to breathing, coughing, weight loss and reduced appetite, and in advanced cases it can cause life-threatening bleeding.
The condition can be treated if diagnosed in time and preventative products are available.
To reduce the risk owners are advised to stop their pets putting molluscs in their mouths, bring in dog toys from the garden at night and not play with sticks that can harbour larvae.