October 13, 2023

All dogs carry Demodex mites, which the mother passes to her pups in their first few days of life. Unlike sarcoptic mange, demodectic mange is not contagious to other dogs or humans. While sarcoptic mange mites live just under the skin’s surface and cause intense itching, Demodex mites live in hair follicles and seldom cause any problems. A daily bath with a special medicated shampoo and a course of Bravecto tablets (fluralaner) usually clears up the condition. 


Healthy dogs usually don’t have any problems with mites. Infestations that develop into demodectic mange are frequently a symptom of a compromised immune system that cannot control the rapid increase of the skin mites, which a vet can diagnose with a skin scraping. Even though this type of mange is not contagious, visually, it can look quite frightful when the dog loses hair in patches all over its body. 


On the other hand, sarcoptic mange is a cause for concern, especially in urban areas where the habitat of roaming foxes overlaps with our domestic dogs. Foxes can and do become infected with sarcoptic mange. Several thousand female Sarcoptes scabiei mites may burrow into a single square centimetre of skin, depositing an accumulation of tissue fluids and debris on the fox’s skin, which forms an intensely itching crust up to 1.5 centimetres thick. The animal will chew or scratch obsessively at the affected area, causing a loss of hair and skin lesions that often become infected. As the mites burrow, they feed on tissue fluid and lay their eggs. Subsequently, on maturity, they extend their mothers’ burrow system. A severely infected animal may be host to several million mites. Sarcoptic mange is highly contagious. Over 30% of foxes can be infected in specific clusters depending on population densities. Following the 1994 mange outbreak in the Bristol area of the UK, the fox population decreased by 95%. While numerous foxes died, mange infestation also reduced the reproductive capabilities of males and females. In subsequent years, similar numbers have been recorded in various European outbreaks. 


Even though the infection can clear up on its own, it will spread all over its body if the animal cannot overcome the infestation, resulting in generalised skin lesions, thick crusts, and foul odour, with an increase in bacteria and yeast, will eventually lead to emaciation and death.


In a Swedish study, researchers intentionally infected three red foxes with Sarcoptes scabiei. The first sign of mange appeared in all the foxes thirty-one days after infection. Over the following months, two of the foxes developed severe symptoms, one of which died 121 days after being infected. Sarcoptic mange is highly contagious to dogs and humans, although they cannot complete their lifecycle in humans and rarely survive more than a few days. Because mites can survive between 3-21 days without a host, on the ground, and on vegetation, even in cold weather, we are advised to keep dogs from areas that foxes frequent to prevent infection.