Certain parts of a dog are vulnerable
Q: I usually take my two Labradors with me when I tend to my horses and have noticed that there seem to be a lot of horseflies around this year, which can give a nasty bite. I generally spray myself with insect repellent to keep them away from me, but what can I do to protect my dogs, assuming there is a risk of them being bitten too?
A: Dogs that spend a lot of time outdoors, especially in a farm environment, are certainly at risk of being bitten by flies. A single fly bite may not do much damage, but multiple bites can lead to skin irritation that can sometimes become quite serious.
Flies can’t usually bite a dog’s body because a thick layer of hair or fur protects them, but there are certain less well-protected areas that are more vulnerable, such as over his ears and around his legs, nose and muzzle. A bite or two in these areas is likely to cause no more than minor pain and irritation.
The more a dog is bitten, however, the more he will rub or scratch himself and each time a fly bites it punctures the skin and creates small ulcers that ooze blood. In severe cases, these small wounds can become infected and, in turn, more likely to attract flies.

Protect bitten areas with a thin layer of Vaseline
Dogs and horsefly bites
If you see horseflies congregating around your dogs or you notice small blood spots on their ears and nose, you can assume that they are being bitten.
Protect them by using fly repellent, which is available at your local pet store. Alternatively, products intended for flea and tick control may also protect dogs against flies.
Can dogs get colds?
Q: My dog has suddenly started sneezing. Can dogs get colds and flu like humans? Over the past few days…
Can you prevent arthritis in dogs?
Q: Is there anything that can be done to delay or prevent the onset of arthritis in older dogs? Controlling…
If a dog sustains multiple fly bites, protect the area by applying a thin layer of petroleum jelly or Vaseline; remember to reapply it if your dog goes swimming or the area otherwise becomes wet.
Clean any open wounds or sores daily with mild soap and water and apply an antibiotic ointment to prevent infection.
Keep the dog indoors as much as you can until the wounds heal completely.