Dog owners often complain about their dog’s odor. It is important to recognize that dog odors have many sources, both natural and un-natural.
Natural Dog Odors
Dogs naturally produce secretions whose function is to allow for other dogs to recognize them as dogs and as individuals. People do not always appreciate these signals! Natural dog odors are most prominent near the anus, near the ears, and around the footpads.
Skin Glands: Dogs do not produce sweat for thermoregulation. Dogs do have sweat glands, though, called apocrine glands, associated with each group of hairs. It is suspected that these glands produce pheromones or chemical signals for communication with other dogs.
Dogs also have sweat glands on the pads of their paws and on their noses that help keep these moist and functioning properly, the eccrine glands. On the paw pads, natural micro-organisms living in the surface layers contribute to the typical odor of dog paw pads, which is a little like the odor of Cheese puff snacks! This odor is much more noticeable on dogs with moist paw pads than on those with dry pads.
Dogs also have numerous glands in their external ear canals called ceruminous glands and sebaceous glands. Together these two sets of glands produce natural ear wax, or cerumen. Micro-organisms live naturally in this material and give the ears a slightly yeasty odor even when healthy.
Dogs, like all carnivores, have two scent glands or anal sacs that communicate with the surface of the skin by ducts that open on either side of the anus. They produce a natural secretion that varies from thin and yellowish to pasty and grayish and with a very strong musty odor. A small amount of this material is normally deposited when dogs defecate and a large amount may be extruded when a dog is frightened. This secretion is thought to leave a signal to other dogs telling them who left fecal deposit. This odor is also the signal being sampled when strange dogs investigate one another by sniffing out the anal area.
Another source of odor that can be considered natural results from a common dog behavior. Dogs like to roll in and mark themselves with some natural products of other animals in their environment, including fecal deposits of natural prey animals. One of their favorites is rabbit droppings. This might be a method of communicating with pack members about the other animals that are active in the pack home territory – a behavior left over from ancestor wolves.
Un-natural Sources of Odor on Pet Dogs
Poor grooming of a dog with long, thick or corded hair can cause the haircoat to be a source of unpleasant odor. A coat that is not kept clean and groomed can trap dirt and other substances with unpleasant odors and if chronically wet, it can harbor lots of bacteria and yeast. Some dog breeds just depend on people to keep their coats healthy and odor-free!
Skin diseases can cause abnormal odors on affected dogs. Allergy causes increased sweating, and this creates a musty odor. This is termed hyperhidrosis, and it encourages yeast infection or bacterial skin infection. These micro-organisms produce odors as well. Dogs with seborrhea or keratinization defect, and dogs with deep skin folds (such as on the face of an English bulldog), are subject to secondary proliferation of bacteria or yeast on the skin surface as well.
Ear disease (otitis) is a common source of odor in dogs. The smell can be yeasty or actually smell like sewage. Anal sac disease or excessive anal sac production can cause a very musty pungent odor.
Anal sacs can become abscessed and infecting micro-organisms produce odor.
Dental disease or mouth ulcers can produce bad breath (halitosis). Dental calculus harbors numerous bacteria that produce the odor. Dental disease can also lead to excessive drooling, causing skin around the mouth to become infected, leading to more odor production.
Some medications, especially antibiotics, or medicated shampoos have odors that owners may find unpleasant. Chlorhexidine is a common disinfectant incorporated in skin medications that some people find has an unpleasant smell. Also, some dog foods based on fish meal or with added fish oil can make for fishy-smelling dogs.
Flatulence can be a problem for some dogs. This may be diet-related or a sign of gastrointestinal disease. This, in fact, may be the most commonly noticed source of unpleasant odor from dogs feed cereal-based commercial dog foods.
Skunks and dogs don’t mix well and a dog may be sprayed in the encounter. This results in an over-powering musky acrid odor that remains apparent in the ‘skunked’ dog’s coat for many days or even weeks until steps are taken to neutralize the odor.