Horseflies-Borne Diseases in Dogs and Cats

Common info

Horsefly is a type of blood-sucking insects with biting behavior which often causes severe pain in the bitten creatures.  It looks like a fly but is larger in size with more noisy flight. Horseflies can be seen all over the world, and are called under different names based on the regions they are found, including gadflies, breeze flies, zimbs or clegs. In Australia, they are called, "March Flies" while in some areas of Canada, they are referred to as, “Bull Dog Flies”. The common symptoms of Horseflies-borne diseases in dogs and cats including severe itching,  blood, and pus draining from the skin, etc.


Horseflies are commonly found in Europe, the Middle East and the East, esp. around Palearctic, mostly in the forest areas. An infestation is often caused by female horseflies due to their biting and blood-eating behaviors found in both humans and animals.


Among dogs, 1 or 2 horseflies’ bites may not have any severe effects in them. However, more bites will cause the wounds to open, with blood repeatedly draining, attracting these horseflies to eat the blood. In some cases, this may result in the bitten wounds being infected.  


  • Otitis
  • Blood and pus draining from the skin
  • Skin inflammation
  • Severe itching

The symptoms of Horseflies-Borne Diseases in dogs and cats include otitis, blood, and pus draining from the skin, severe itching, and skin inflammation.

Treatment and Prevention

Clean the bitten skin with liquid soap or plain warm water using cotton, followed by an application of antiseptic, such as Betadine, on the wound.  After that, cover the wound with a bandage.  Wounds around the ear can be treated by applying Neosporin on them, to relieve the inflammation.

  1. Wikipedia | Haematopota pluvialis
  2. Petguide | Treating horse fly bites dogs
  3. F. Baldacchino, L. Gardes, E. De Stordeur, P. Jay-Robert and C. Garros. 2014.Blood-feeding patterns of horse flies in the French Pyreness. Veterinary Parasitology.199:283-288.
  4. R. H. Gooding, B. M. Rolseth and A. W. Thomas. 1977. DIGESTIVE PROCESSES OF HEMATOPHAGOUS INSECTS X. Effects of mammalian sera upon two trypsins from female horse flies and deer flies (Diptera: Tabanidae).14(1):23-38.
  5. Tanasak Changbunjong, Benjaporn Bhusri, Poonyapat Sedwisai, Thekhawet Weluwanarak, Eakanan Nitiyamatawat, Theeraphap Chareonviriyaphap, Jiraporn Ruangsittichai. 2018. Species identification of horse flies (Diptera: Tabanidae) in Thailand using DNA barcoding. Veterinary Parasitology.259:35-43.
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