Why Does My Dog Or Cat Have Bad Breath And What Can I Do About It?

Why Does My Dog Or Cat Have Bad Breath

Tooth And Gum Problems And What I Can Do?

Ron Hines DVM PhD

Read about natural ways to deal with bad breath here


A lot of things can be going on in your dog or cat’s mouth without you realizing it. It is usually a dog or cat’s strong breath (halitosis) that motivates pet owners to visit their veterinarian and inquire why. In fact bad breath is probably the second place of all reasons dog owners visit their vets. In the UK that is the case – just behind the first place reason, ear infections and just ahead of the third most common problem, anal sac impactions and scooting. (read here)

Halitosis is the the medical term for bad breath. Halitosis is to what is occurring in your dog or cat’s mouth as smoke is to fire. Now there are medical conditions that can occasionally cause a change in your dog or cat’s breath odor: the acetone-like smell that sometimes accompanies diabetic ketoacidosis (read here) , the gastric reflux and vomiting that accompanies indigestion  (read here) , esophageal problems (read here). Although the scents of those conditions are distinctive, they are not the intense, offending odor that drives pet owners to visit their veterinarian. What does are mouth infections. In perhaps 2% of the cases, a bone, toy or sharp object might be lodged in your pet’s mouth or a tooth fractured. In the rest, the source of the odor is gum infection that accompanies heavy tooth tartar buildup and the putrid, decaying food that surrounds it.

Certain bacteria thrive in that rancid decay. Common among them are species that liberate sulfur-containing compounds with exceptional bad odors (eg Porphyromonas and Prevotella). (read here & here) These, and similar bacteria liberate sulfide-containing compounds (volatile sulfur compounds) that are responsible for the odor. Besides their offensive odor, these compounds are toxic in their own right. (read here)

Bad breath, gum and periodontal disease in dogs and cats often go hand in hand with other serious health problems. Clumps of bacteria and diseased tissue have the ability to enter your pet’s general blood circulation from infected sites in its mouth. In humans, periodontal disease is a known risk for heart disease, It probably is in our pets as well. (read here) Periodontal inflammation can even raise the blood level of proBNP, one of the major blood tests your veterinarian uses to detect heart disease your dog or cat. (read here) So it is important to treat and control periodontal disease and associated mouth problems in your pet – even if its breath odor is not that objectionable to you. As dogs and cats age, those that receive primarily soft diets are particularly prone to face dental and mouth issues. This problem tends to be considerably more severe in smaller dogs. Veterinarians are unsure why. Perhaps toy breeds are more manipulative in demanding the foods their owners eat – and more importantly, getting it. The teeth of small breeds are also often crowded and misaligned. Little breeds also tend to live a long time – giving dental problems time to develop. These toy breeds might have genetic predispositions to these problem as well. We really do not know. I put lifestyle at the top of the list because I have see many senior chihuahuas and other tiny breeds with excellent teeth. What they all have in common is a crunchy diet and a lack of access to soft table scraps.

Soft pet foods, when mixed with saliva, leave mineralized residues on and around your dog and cat’s teeth that attract and protect unhealthy bacteria. Those bacteria organize into biofilms. With time, these layers thicken into hard, mineralized tartar (calculus). The portion of the tartar that is in touch with the living tissue of the gums is the most damaging. Mechanical irritation from this tartar, along with irritating compounds the bacteria in it release, produce chronic gum inflammation. That eventually leads to the loss of bone and cementum that anchor your pet’s the teeth. As inflammation continues, their gums slowly recede exposing softer, more porous root material . Unlike us humans, dogs and cats rarely develop cavities. A fractured tooth may lead to a root infection and cats occasionally suffer from odontoclastic tooth resorption, but tooth cavities as we experience them are quite rare in cats and dogs. Remarkably, pets with periodontal disease condition rarely eat less.


Early in dental disease, the plaque (tartar/calculus=calcified plaque) that accumulates is no more than a thin brownish or yellowish coating on the sides of the teeth. It is most noticeable and thickest on the outer (lateral/buccal) surface of the larger molar teeth – the side adjacent to the cheeks and lips. In severe cases the margins where teeth and gums meet become highly inflamed, bright red and bleed when they are touched – like the cat in the photo above.

What Can I Do When My Dog Or Cat Already Has This Problem?

The first thing to remember is the difference between prevention and treatment. Bad breath and tooth problems in dogs and cats are easily prevented by selecting foods for them that replicate their natural diets and prevent the issue from ever occurring. Various treatment your veterinarian can offer will slow the progress of periodontal disease and the bad breath it causes. But it will not reverse much of the damage that has already been done. That damage is gum recession – a slow shrinkage of the healthy tissue that surrounds the base of all teeth that eventually loosens them. Various techniques, in order of sophistication include: manual removal of tartar with scrapers, ultrasonic scaling, root planing and periodontal flap surgery with bone grafts. I’ll start with treatments and get to prevention later in the article:

Scaling With Tartar Scrapers


The scaling instruments you see in the first image above are very effective in removing the majority of tartar (plaque) from a dog or a cat. Most pets find the sensations that accompany using them intimidating – or at least annoying. Depending on your pet’s temperament, and the age at which you introduce them to the feel of the procedure, many pet owners can perform periodic tooth scaling at home. Sometimes, a mild tranquilizer is quite helpful. You will find many videos on YouTube that will instruct you how it is properly done. Overly vigorous or incorrectly performed scaling at the gum line can seriously damage the gums.

What About The American Veterinary Dental College (AVDC)?

The AVDC is an association of veterinarians that specialize in sophisticated dental techniques. These veterinarians are without doubt highly skilled in advanced dental treatments  that your local veterinarian would be unlikely to attempt. The AVDC jealously guards their turf and they define their turf broadly. They are dead set against anyone but veterinarians performing tartar removal. Some of their statement are quite over-the-top – a form of cruelty to the great many dogs and cats that cannot afford their services. They also subtracts from the believability of other, quite-legitimate, points they bring up. The non-veterinarians who provide these services and whom they pursue in administrative courts are generally pet groomers. I know for a fact that some of those people do an excellent job of delicately removing tartar from your dog and cat’s teeth as well as under its gum line; but I also know that others do a job that leaves a lot to be desired. In a perfect world, all pet owners would all be wealthy enough to afford the services of an AVDC-member veterinarian, there would be no homeless pets, and Medicare would cover the dental needs of the treasured pets of lonely elderly folks living on meager pensions. That is probably is not going to happen. In light of the Greater Good, perhaps the AVDC needs to reconsider their stance and offer dental assistant certification programs. That’s probably not going to happen either.

Anesthesia-free tooth care is an acceptable choice for dogs and cats whose temperament allows it. It is never acceptable for fearful, overly-active or aggressive pets. It is also not a substitute for a dental specialist’s care or when periodontal disease, bone loss and infection are advanced. Its your job as a responsible pet owner to see to it that your pet’s diet, food choices, chew-treats and home hygiene never let mouth problems get to that stage. The AVDC states that having skilled non-veterinarians assist in keeping your pet’s teeth clean is dangerous. However, they present no data to support that. On the contrary, all evidence suggests that frequent removal of biofilms and tartar from teeth – including that which develops at and just under the gum line – delays and prevents more serious dental disease from developing later. (read here ,  here  & here) What is important for your pet is that it be done professionally, not that it be done by professionals. It is also important that deep root probing and planing not be done without sufficient cause nor over-zealously done. ( read here & here)

Ultrasonic Scaling


Your veterinarian begins a dental cleaning with the same tartar-removing instruments and techniques. However, tartar scrapers do not remove every bit of tartar. For that an  ultrasonic scaling unit similar to the above photo is required. These units use transducers to generate very rapid vibrations at the tip of the probe. When in contact with a tooth, these vibrations produce tiny bubbles of water vapor that implode releasing heat and pressure that loosens residual tartar. Because this occurs within a constant jet of water, no heat or discomfort occurs. The problem is that the noise of the apparatus frightens dogs and cats. That is why most veterinarians insist that pets be anesthetized or heavily tranquilized before attempting to use these machines. When the veterinarian or technician assigned to the pet is finished, they often follow up with a low abrasive polishing paste to leave as smooth a tooth surface as possible. A smoother enamel gives bacteria less ability to cling to the tooth surface. 

Root Planing


Root planing attempts to remove tartar that has accumulated deep below the gum line on your pet’s tooth root surfaces. These surfaces are much rougher, softer and more porous than the exposed upper enamel surface of teeth. When they are affected by periodontal disease, healthy gum tissue will no longer bind to them. The goal of root planing is to remove the toxic most outer layer of cementum that shields the dentin root structure. The goal is to create a surface that healthy gum tissue can attach to.

Periodontal flap surgery – Sometimes With Bone Grafts


When dental x-rays and your veterinarian’s examination show that tartar extends far below the gum line, that tartar needs to be removed. In many pets, that can be done sufficiently well by the root planing technique I mentioned earlier. But in some dogs and cats, a larger portion of the tooth root needs to be exposed to do it well. The veterinarian cuts a three-sided flap of tissue covering the root and bends it outward on the remaining tissue hinge. I drew an approximation of that in the diagram just above. That allows a close examination of the tooth root’s condition and gives room to remove all tartar, devitalized tissue, and to smooth the contours of the root. The surgical technique in making this flap is quite similar to that used to extract deep-rooted teeth. When that is accomplished, the veterinarian stitches the flap back into place with very fine suture. Often, living tissue that surrounds the tooth can then reestablish natural bonding to the tooth root better.

Bone Grafts


In advanced cases, so much bone and surrounding tissue has been lost that a pocket is formed.  If you choose to, there are advanced option to treat that as well. They are best performed by a veterinarian who specializes in restorative dentistry. It requires a series of procedures beginning with removing as much reachable tartar as possible and, perhaps, antibiotics to lessen the degree of mouth infection. Several types of replacement material meant to stimulate the body to produce its own bone are commercially available. They are meant to be a filler and a scaffolding to facilitate that process.  They also act as a mineral reservoir. These products have all been formulated to not be recognized by the pet’s body as being foreign material. So in themselves, they cause no inflammation. Some of these products are called autogenous bone graft material or autografts. They are taken from elsewhere in the patient’s body. When used, they have the possible advantage of containing living tissue that the pet’s body will accept. They are rarely performed other than in a research setting. Another type of grafting bone is allogenic. That is non-living bone that has been harvested from other patients, ground up, sterilized, and proteins that the body would recognize as foreign removed. It serves only to fill the void and act as a framework or scaffolding to be replaced by the body with its own bone and tissue later. If it is not derived from the same species of animal, it is an xenogenic grafting material. Other bone grafting material are entirely or partially synthetic substitutes. Canine bone, processed for this purpose is commercially available. (see here) If still online, you can view a YouTube video on its use here.  Not all recent research has found the results of bone grafting to be superior to simply scrupulously cleaning and smoothing the root area exposed by a flap. (read here)

Some form of membrane or protective barrier film is generally placed around all of these products to keep them in place during the 4-6 months it can take for the pet’s own tissue to fully replace the grafted product. Most of these commercially available membranes are composed of resorbable cross-linked collagen. Unfortunate beagle dogs are a preferred model in developing dental bone graft products. You can read articles on their use in dogs for that purpose. (read here,   here and here). None of these techniques are likely to succeed long-term if mouth infection is not adequately controlled. Post-surgical antibiotics and life style changes can help with that. Each cat or dog is unique in its immune defenses and oral pathology, so outcomes are unpredictable.

Regenerative Dentistry

The use of mesenchymal stem cells derived from the fat of individual pets or the substitute use of  platelet-rich plasma might also be helpful as an adjunct to periodontal flaps and bone grafts. No well-controlled studies proving its effectiveness exist but you can read about these experimental procedures here and here.

Sprays And Gels

There are a large number of sprays and gels marketed to treat dogs and cats with periodontal disease and bad breath. Some contain essential oils and antioxidants, others antiseptic rinses (chlorhexidine). Still others contain enzymes. Some advertise as a “PET DENTIST IN A BOTTLE”. These products can reduce your pet’s oral odor because they are perfumed and inhibit the replication of bacteria. However, they do nothing to address tartar buildup, lodged food particles, and oral inflammation that are the causes of the smell. They also inhibit protective oral bacteria as well as the damaging ones. There are over 700 species of bacteria that can inhabit your mouth ; and one can assume dogs and cats harbor quite a few helpful bacteria as well too. So the effect of the long term use of sprays and gels that kill them indiscriminately is problematic. The oral cavity is the entrance to the digestive tract, and like the other portions, bacteria play positive as well as negative roles. Better to attack the underlying cause of the problem by eliminating tartar.


Brushing Your Pet’s Teeth

Brushing you dog or cat’s teeth frequently, gently and thoroughly has the same positive effect on your its gums and teeth as it does on yours. But it is time consuming, many pets dislike it and the vast majority of pet owners do not brush their pet’s teeth. Just like for you, it is not a cure-all against the various problems that affect the mouth. It is also not a substitute for feeding your pet a diet that has a natural, dental-friendly consistency or adding food items that compensate for the unhealthy things we feed our pets. Again, there are videos on YouTube that will instruct you how to do it properly. Use a toothpaste and toothbrush or finger brush designed for pets, not for humans. I have no experience using wipes. I prefer an application device that gets between teeth. To see the benefits from tooth brushing, the pet has to either be started on the procedure early in life (the earlier the better) or the pet’s teeth need to be professionally cleaned and unsalvageable teeth removed before starting a successful tooth brushing program. Start by simply massaging your pets lips and mouth with your fingers. When your pet is comfortable with that, get it accustomed to having its lips and teeth rubbed. Place a little of the toothpaste on your fingers as you do this. If you are fastidious, wear gloves. Most of the tartar (~80%) forms on the outer (buccal, cheek side) surface of the teeth so you do not need to spend as much time cleaning the inner surfaces as the outer ones. Begin brushing for very short periods; very gently and very slowly. When you are done, give your pet praise for being a good patient. Proceed longer and more thoroughly gradually from day to day and stop when your pet begins to squirm or show annoyance. Within a few weeks you should be able to do a rather thorough job. Some pets by nature resent tooth brushing more than others. Obstinate or fearful pets will have to rely more on therapeutic dental chews and dental diets.

What Else Can I Do To Prevent My Dog Or Cat From Developing Advanced Bad Breath And Dental Problems?


The Primary Factor That Determines Whether Your Pet Will Face Dental And Breath Issues During Its Lifetime Is What You Feed It.

I listed the time consuming and costly procedures first. That was to motivate you to take some much easier steps now – before your pet reaches that point so those steps will never have to be taken. Letting your dog or cat determine its own food choices is no different than letting a toddler make his food choice decisions. You are the parent, you need to make those decisions, not your pet. And just like toddlers, the longer in their lives you procrastinate, the tougher it will be to correct ingrained bad habits.

Tartar only forms on the teeth of carnivores when the foods they are eating do not scrap off bacterial biofilms as they form. This occurs naturally when canines and feline eat the diets their teeth architecture and mouth were designed for. It does not occur when they eat canned food, table scraps and soft treats. Ordinary dry kibble does a better job than those other food items, but it is not sufficiently abrasive to mimic a natural diet. In the last few years, prescription and non-prescription “dental diets” have become common. In shape, size and consistency they attempt to increase the cleansing action that occurs as pets eat them. I do not know of any independent studies that evaluate their effectiveness.

What I do know to be effective are treats that require gnawing and extended chewing. Things like fresh pig ears and snouts and cow tracheas. Soft bones (cancelous bones) like ribs tend to be swallowed in amounts that can cause indigestion. With the demise of independent butchers, those preferred items are hard to find. I never trust the quality of chew items hanging on hooks at pet supply stores, supermarkets and retail centers or those composed of imported hides and sold by veterinarians. Dogs and cats retain glistening teeth and healthy gums when they are given meaty bones. I used to feed my geriatric beagle colony at the NIH oxtails. These were retired breeders from research kennels. Only one of the 30 dogs had an incident of a portion of the oxtail lodging crosswise against it palate. My kennel man removed it easily. Once these dog’s teeth had been ultrasonically cleaned on arrival, they maintained a tartar-free mouth when given the tails twice a week. You can read about how these food items maintain oral health here.

Dental Chews And Treats

The best alternative to grizzle and appropriate bones for keeping your cat or dog’s teeth and gums healthy are the new generation of dog and cat chews. Within the last few years, a number of companies have developed heat and injection pressure-molding processes that produce flavorful, digestible treats that are hard enough to keep a pet’s teeth clean. Most have a high content of cross-linked (“beaded”) potato starch. Some contain similarly processed corn starch and calcium carbonate. In the vast majority of pets, given in appropriate amounts, they are safely digested. One of the new ones, Milkbone™’s “Brushing Chews” for example, contain rice flour, modified food starch and chicken by-product meal as their first three ingredients. Because these products are so effective, there is a lot of jockeying for sales volume and claims-hype within the industry. (see here)  A number of manufacturer-generated studies (not the most unbiased source of information) appear to find them helpful. (read here & here)

No preventative dental plan for your dog or cat can be perfect. Chews and treats are occasionally dangerous. Some dog’s are gulpers that swallow things greedily whole or in large bits. They are not the kind of pets that would benefit from these chews anyway because it is chewing and gnawing that cleans teeth. When you offer these products, follow the directions on the package. Select the size that is right for your pet, give them one-at-a-time in limited numbers while you are present. Preferably start when they are young. As with all things eaten, some pets digest them better than others. These are modified starch-containing products. Dogs differ in their ability to digest starch (carbohydrates) based on the amount of amylase they produce. It appears that the closer genetically they are to wolves, the less ability to digest starch they have. (read here) Whether domestic cats also differ in these abilities is unknown. But I believe that on the whole, these compressed products are considerably safer than jerky, rawhide, store-bought preserved bones and treats with imported ingredients. NEVER, leave these chews where dogs can consume them in large quantities. At the least, they will get a tummy ache, or worse. If your pet is overweight, remember, these products have lots of calories too – cut back their calories elsewhere. Read about that here.

If you are still apprehensive, try one of the prescription dental diets veterinarians sell for cats and dogs.

Extraction Of Diseased And Loose Teeth

Once the ligaments that fasten teeth to the bone of the jaw have been extensively damaged by periodontal disease and gum recession (shrinkage) scaling and ultrasonic cleaning will not heal them. Mildly loose teeth can sometimes be preserved by cleaning, several weeks of doxycycline or other therapy provided either with oral tablets or oral patches (although the need for post-treatment antibiotics has been questioned. Your pet’s severely loose teeth are best removed for its general well being. They are a constant source of infection and discomfort. Dogs and cats do very very well with few remaining teeth. I believe that owner and veterinarian resistance to extractions are due primarily to projecting their fear of visual appearance onto their pets. There are exceptions – guard dogs, police and work dogs, perhaps a show dog or two.

Tooth Restorations

Any cosmetic dental procedure that is available for humans is available for your pet – usually performed by a veterinarian who does nothing else. I rarely send dog or cat clients to them for fillings, crowns or implants. When I do, it is generally for repair or replacement of a canine tooth (fang) broken off through trauma. As I just mentioned, I have not observed that dogs or cats with multiple or total tooth extractions lead any less happy lives than those who go to dental specialty clinics for complicated dental restorations. Dogs and cats do not contemplate their appearance in the mirror as we do. They are not vain. When a pet looses one of its bottom canine teeth, its tongue will usually protrudes outward on the same side. That does give them a comical appearance that might offend some pet owner’s sensibilities. But it causes them no pain, self-consciousness or discomfort.

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