Dealing with flies Print E-mail
News - Rubrieke
Monday, 12 December 2016 15:22
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Dr Liesel van der Merwe is a small animal medicine specialist. Send her your questions: This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Dr Liesel van der Merwe

It is summer, it is warm and thank goodness the rain has started … but the flies are also out.

Some flies, such as the stable fly (Stomoxyscalcitrans), are major pests. They are obligate blood feeders although they spend only the necessary biting/feeding time on the host, digesting their meals while on another quiet surface. They feed on average twice a day – more frequently if interrupted.

The fly breeds in fermenting organic matter, which may or may not contain dung, such as lawn clippings or compost, and thus are associated with a suburban environment rather than just stables.

Their favourite areas to bite are the tips and upper surface ridges of the ear where the dog’s coat is thinner and the blood vessels are close to the surface. They will also bite on the thinner skin of the nose and lower limbs.

The ears are the most targeted, as the dogs cannot prevent them from getting there, except by flapping their ears. These bites are uncomfortable and once the skin is damaged, more flies will be attracted.

Dogs can cause self-trauma by just trying to keep flies off their ears. The persistent head shaking and ear flapping may also cause the development of an othaematoma, which is a large blood blister in-between the ear cartilages.

In cattle, flies can have a major impact on production, causing weight-loss and reduced milk production due to interrupted feeding and irritation.

The initial sign that your dog’s ears are being bitten is a dark granular ‘coffee grain’ kind of crusting on the hair, which is actually dried blood. If you see blood spots or flies congregating near your dog's ears then you can assume fly bites are occurring.

If unmanaged these areas become open sores and ulcerated and I have seen the tips of ears being ‘eaten right away’, leaving thickened damaged wound edges.

Topical Fly Control includes: Advantix and Exspot are the only top-spot flea, tick, mosquito and fly repellent product available. They are toxic to cats. The active ingredient stored in the skin helps to repel those biting flies just as effectively as products applied to the ears themselves. Exspot needs application at least every two weeks to be effective, whereas monthly application of Advantix is adequate in most cases.

Pyrethroid-based topical fly repellent sprays and ointments are cost-effective options. These are toxic to cats. If your cat grooms your dog, do not use it. Apply ointment around the face and ears and use spray on the body. Rub into the skin until the ointment disappears.

Repellent action lasts for two to three days, depending on the weather. If you have large dogs or are a multi-pet household, the pyrethroid spray packaged for horses may be a more cost-effective purchase.

The use of the spray could lead to steeple chase races around the garden, as my dogs have developed an aversion to the process and can spy me with the bottle in my hand at 50 meters. I have to resort to cunning and subterfuge to get them sprayed.

Environmental fly control is difficult, as you need to treat environmental ‘resting places’ and not just the animal affected. Animal areas should have fly bait or traps to capture adult flies before they can lay eggs. Even removing some flies from the breeding population will decrease the next generation. 

QuickBayt is a powder which, when mixed with water, is applied to walls and lasts for four weeks. It has a pheromone which attracts flies. The toxin is Imidacloprid, which is an insect neurotoxin and has low toxicity to mammals, but is very toxic to bees when used on plants.

Any food scraps or waste products left unattended in your yard will attract flies. Washing out your dog’s dish after each feeding and picking up dog faeces several times a day will help you maintain an outdoor space that is less appealing to flies.

In addition, there are several herbs you can plant that may repel flies (but usually only when crushed): basil, bay leaf, mint and rosemary, lavender, sweet woodruff and tansy.

And yes, I have a highly educated vet friend who swears by this . . . Another dog-friendly method of environmental fly control is less conventional than traditional cleanliness, but has a reputation for effectiveness and involves nothing more than a zip-top bag of water and some coins.

Despite lack of scientific explanation for its effectiveness, flies can be successfully repelled by hanging a clear bag of water or clear two litre plastic soda bottle with one or more copper coins in it around areas that are fly-infested.

So, while it can take a little bit of work, the problem of biting flies is actually fairly simple to solve.

Remove what the flies are attracted to (the bleeding ears and faeces), and then keep them away with Advantix or a fly repellent cream. Just watch out for those dangerous and ineffective remedies involving human skincare products, essential oils and garlic (very toxic to pets).

Mosquitoes are also a problem, but they seem to prefer biting cats to dogs, especially on the nose and bridge of the nose and sometimes the ears. Some cats are allergic to these bites and develop large red raised areas which appear very similar to skin cancer on the nose.

There is no repellent which is safe to use in cats, and most of the herbal repellents, with their strong scents, will actually cause cats more discomfort as they have such a well-developed sense of smell.

The best is to take your cat to your veterinarian if you see suspect lesions on the face and then treat accordingly with cortisone tablets as it flares up.


© 2020 Die/The Bronberger