Could I get a little more information?
Has the dog been physically examined - by you or a vet?
Does the dog have long hair or short hair?
Do you notice the dog scratching? If so, where?
Is he acting normal otherwise? Eating, drinking okay?
Dogs with skin infections can smell terrible. The same can occur with ear infections. They can have a bad enough smell to fill a whole room like you are describing. With hot spots and areas of bad infection there can actually become areas that become infected and necrotic (dead) that can add to the smell. One thing that I worry about with dogs with long hair and skin issues is an infestation of maggots. I do not know if this is possible in the area where you live at this time of year - but if it is possible I would examine the dog very closely for this problem. The smell can definitely be like something has died. What happens is that there is an area that becomes infected and stays moist. Underneath a heavy coat in a damp environment is a very attractive spot for flies to lay eggs. The maggot then feed on the debris and can even start in invade the body underneath the skin. If you notice any maggots I can help you with ideas to remove them.
For treatment of skin conditions and ear infections will probably require antibiotics. You can try bathing the dog and treating yourself at home - but it may not be successful. I would recommend using clippers and removing all hair from any areas of skin that appear to be infected. This helps the area to stay dry and heal. You can shave the whole dog short as well. This can help to identify previously hidden skin problems as well. The infected areas can be cleansed with benzoyl peroxide shampoos and may heal on their own if you can keep the dog from digging at them. Neosporin type ointments can also be helpful in localized lesions. I would also recommend cleansing the ears with a commercial ear cleaner.
Allergies can be an underlying cause for itching and subsequent infections. Benadryl has been frequently prescribed for this problem at 1mg per pound of body weight twice daily - I wouldn't exceed 50mg however. This usually takes several days of continued use to notice a benefit. Flea allergies are also common - which can cause severe reactions from just a few bites. I recommend treatment with frontline as this seems to be the best product for killing the fleas before they have a chance to bite - thus preventing the allergic reaction.
I hope this was helpful. If you need more information just reply with followup question.
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I would search for them down by the skin in any area the the fur seems moist. They seem to be especially common around the hind quarters and around the anus. Any area that there is moisture under the hair is possible though. There may or may not be obvious sores in the area. I have shaved several dogs infested with maggots that will have an intial area of infestation and other areas in different parts of the body that I didn't originally even suspect. If this is a possibility with the weather in your area I would suggest shaving the dog's coat very short so you can see the skin well. There is a pill called capstar for fleas that is effective against maggots as well.
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