?Tis the season to be bitten . . . PDF Print E-mail
News - Rubrieke
Thursday, 21 October 2010 04:47
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In this column veterinarian Dr Liesel van der Merwe provides practical assistance for common problems in companion animals. She is a specialist physician at the Onderstepoort animal teaching hospital and a senior lecturer in the section of small animal medicine. Send your questions to This e-mail address is being protected from spambots. You need JavaScript enabled to view it


Dr Liesel van der Merwe

I have just returned from a weekend in the country outside Bela Bela with my dog Gemma. Now Gemma is an escape artist and I ended up going for a run with her off her lead and she went off into the bush to explore. As I was running along I saw three nice fat snake “footprints” in the sandy road. This, needless to say, did not instil a relaxed feeling. What to do if your dog is bitten by a snake? Well, all I can advise is to get it to a vet as soon as possible.

There are two main types of snake envenomations. Puffadders have venom which causes severe tissue damage and swelling; these are called cytotoxic snakes. Cobras and rinkhals cause paralysis and are called neurotoxic snakes. Some cobras, such as the Mozambican cobras, have dual action. The tree snake causes blood clotting but the position of the fangs in the back of its mouth, as well as those of the neurotoxic mamba, make them uncommon culprits in dog envenomations.

Unfortunately we do not always see what has bitten our dogs. If you or your dog has killed the snake, bring it in, but be careful not to be accidentally “bitten” even if the snake is dead and make sure it is not just “playing dead”. This may help your veterinarian to decide which treatment course to follow.

Not all snake bites result in symptoms, because the snake does not always inject venom. I would, however, not suggest that you “wait and see first at home” because then you might not have time to get to the vet once symptoms begin showing. If your dog has been sprayed in the eyes with venom you should immediately rinse the eyes with copious amounts of water, cold tea or milk.

Adder bites, with the severe tissue swelling and damage, can cause breathing problems as the dogs are most often bitten on the head and neck. The dogs will generally just show severe tissue swelling which may result in signs of shock and sometimes severe septicaemia due to tissue breakdown and bleeding into the affected area.

Treatment is mainly aimed at supporting the blood circulation and kidneys with intravenous fluids and even sometime blood transfusions. Anti-venom can be injected to try and bind some of the circulating venom, especially in smaller dogs such as fox terriers, Jack Russells and daschunds, but is not an essential component to therapy.

Dogs that have been bitten by a cobra will show weakness and will die from paralysis of the chest muscles and suffocation. These signs can be immediate or can be delayed. If a small dose of venom was injected, your dog may only show partial paralysis.

Severely affected patients need to have an endotracheal tube and need to be placed on a respirator or manually ambu-bagged (ventilated) until the venom is worked out of the system. Anything from six to 12 hours are needed for normal breathing to resume and a bit longer to regain full strength.

In these cases the use of anti-venom is crucial to limit symptoms. Once again, rather get the dog to the vet and then decide together, based on how symptoms are progressing, whether it is necessary to use the anti-venom. Anti-venom is polyvalent – which means it is made up against a variety of snake venoms, is expensive and is also a rare biological product. The anti-venom dose is based on an average per snake, and not on the size of your dog.

In general it is recommended that at least four to five vials are needed to counteract the injected dose of venom. If finances are tight I would suggest, especially in neurotoxic bites, to try for a minimum of two vials, which may be what is needed to prevent total respiratory paralysis.

I would recommend that you contact your veterinarian if you are in an area with a high snake population and find out what their antivenom status is. Anti-venom is also obtainable from various hospitals.

 

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