Diagnosing Odor in Cats

Skin odor is a common manifestation of a skin infection. The most common skin infections in cats are bacterial (superficial pyoderma) and yeast (Malassezia dermatitis) infections. Skin discharge and/or odor can indicate that your cat may be suffering from a skin infection.

What are bacterial and yeast infections?

Bacterial infections are usually caused by bacteria that are part of the normal flora of the skin (e.g. Staphylococcus intermedius). For this reason, the infection is not contagious to other animals. In cats that have abnormal skin (e.g. allergies) the bacteria increases in number and causes red bumps (papules) and rancid odor. Some cats with bacterial skin infections also develop excessive shedding, patchy hair loss, and scaling. If the infection is left untreated, it may reach deeper parts of the skin. In these cases, nodules that have a purulent (pus) discharge develop. In most cases skin infections are secondary, so it is very important to pursue an underlying cause. Failure to do so will result in reoccurring infections.

Animals often develop a yeast infection (Malassezia dermatitis), which manifests itself as greasy, red, itchy skin with a rancid odor. Areas most commonly affected include the ventral neck, groin, armpits (axillae), and perineal areas. This infection is also secondary to an underlying disease, most commonly allergies. In some cats this may be a consequence of chronic antibiotic and steroid therapy but, as a general rule, cats do not develop yeast infections after antibiotic therapy as commonly as people do.

Diagnosis of Skin Discharge or Odor in Cats

• History is very important for the proper diagnosis of skin diseases. Your veterinarian will ask questions regarding the age of onset, progression of the disease, and response to previous treatments.

• Skin cytology provides useful information on the type and severity of infection. Your veterinarian may take samples of skin (e.g. swabs or tape impressions).

• In some cases, a biopsy may be necessary to establish a final diagnosis. Some samples may be used for cultures of various types while others may be sent to a pathologist to obtain more information about the cells that are present in the skin.

Treatment for Bacterial Dermatitis

Treatment for bacterial skin disorders is antibiotics. Some of the more commonly used antibiotics include ampicillin, cephalexin, enrofloxacin, clindamycin, clavulinc acid and sulf based drugs.

The minimum length of therapy for superficial pyoderma is 3 to 4 weeks. The minimum length of therapy for deep pyoderma is 8 weeks. As a rule, therapy should be continued for 2 to 4 weeks beyond the resolution of clinical signs.

Treatment of Malassezia Dermatitis​

Systemic therapy is reserved for severe cases. It is important to note that griseofulvin is not effective against yeasts. Ketoconazole, itraconazole and fluconazole are all effective against Malassezia.

Topical therapy as the sole treatment is only effective in mild cases while severe cases usually require systemic therapy. Selenium sulfide (Selsun Blue®) is a keratolytic, anti-seborrheic, degreasing agent that will kill Malassezia (effective in 65 percent of cases).

Ketoconazole shampoo (Nizoral®) is approved in many countries for the treatment of seborrheic dermatitis in people and is usually effective in killing Malassezia.

Chlorexidine at 2 to 4 percent might be effective against yeasts, 0.5 to 1 percent is not effective.

Miconazole (Dermazole ®, Resi-zole® leave on conditioner) is also effective.

Vinegar/water rinse (1/5 to 1/10) is a cheap and effective long-term maintenance treatment to prevent relapses.

At-Home Care for Cats

You will need to shampoo your cat with medicated shampoos. Benzoyl Peroxide is an excellent antibacterial antibiotic (e.g. Oxydex®, Pyoben® shampoo). Other antifungal shampoos contain miconazole or ketoconazole (e.g. Nizoral® shampoo for dandruff is now available OTC).

Contact time is important when using a medicated shampoo. You should allow a 10 to 15 minutes contact time for the product to be effective. Leave-on products are also available on the market for prolonged efficacy.

You may have to administer oral medications (either antibiotics or antifungal medications) to help treat the infection. Compliance is very important. Some cats may require medications for a prolonged time as skin infections usually take a while to clear. Speak with your veterinarian before administering medication to your pet.

If your cat keeps relapsing with infections, it is important to pursue an underlying cause. This will decrease the frequency of relapses and reduce the risk of resistance to medications used for prolonged periods of time.

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Flea Allergies in Cats and Dogs

Fleabites make most pets itch. But did you know—some cats and dogs are allergic to the pests! Your doctor may call this flea allergy dermatitis (FAD) or fleabite hypersensitivity. If your pet has a flea allergy, even one or two flea bites can make your pet's life miserable.

Many cats and dogs are allergic to fleas. In fact, FAD is the most common skin disease in dogs in the U.S. Flea allergies often spike in the summer, and pets that have seasonal allergies are more likely to have an allergic reaction to fleabites, but any pet can get FAD.

Spot the Signs

When a flea bites your dog or cat to draw blood, it injects saliva into your pet’s skin. Flea saliva is irritating to most animals, including humans. But the compounds in it can trigger an allergic reaction in some pets.

Everyday itching from a flea bite isn’t the same thing as a flea allergy. If your pet has FAD, the itching will be intense and last longer. Your pet may itch for up to 2 weeks after a bite and the itching will be severe and damaging to their skin.

Other signs of FAD include:

• A rash on your pet’s skin or raw, irritated, or bleeding areas on your pet’s body. Dogs usually have it near their back legs, stomach, or tail area. Cats are more likely to have it near their neck and face.

• Hair loss, especially in areas where the bites happened

• Small red or pink raised bumps that may look like pimples

• Constant itching, biting, clawing, or grooming

Help Your Pet Get Relief

Unfortunately, this isn't a one and done situation—it's a process.

Step 1: See your pet’s veterinarian. Don’t assume that because you can’t see any fleas, your dog or cat doesn’t have a flea allergy. Often, animals with one groom themselves constantly. They may remove any fleas from their bodies — but the allergic reaction from bites can last for weeks.

If your dog or cat is scratching itself, set up an appointment with your veterinarian. Fleas and flea allergies are common, but it could also be another health problem, like a tick bite. It’s important to get the right diagnosis before your pet starts any type of treatment.

A vet will check your pet’s fur and skin thoroughly for fleas and “flea dirt,” which is flea poop that looks like pepper flakes. It often turns red when it's wet. If the vet suspects another cause for your pet’s itching, they may order certain blood or skin tests to be sure. Your vet also makes sure that your dog or cat doesn’t have any open wounds. If a pet is itching or chewing on itself a lot, bacteria or yeast can get into the skin and cause an infection.

Step 2: Break the cycle. Putting an end to your pet’s flea allergy means getting rid of fleas. Though they're more common in warmer months, fleas can live year-round indoors. Once they lay eggs, new fleas hatch and then lay more eggs, which means your pet is constantly exposed.

Using year-round treatment with a flea preventative medication can help break the cycle and prevent future allergic reactions.

Topical medications and oral meds kill adult fleas. Talk to your pet’s veterinarian about which treatment is best for your pet.

Medication is only half the battle. Fleas don’t actually live on animals. They live in carpets, bedding, and other surfaces in your home and jump onto your pet to eat. That’s why it’s important to wash your bedding, your pet’s bedding, and your throw rugs with detergent and warm water.

To remove fleas, flea eggs, and larvae, vacuum your carpets, larger rugs, and chair and sofa cushions. Empty the vacuum bag or canister afterward. Make sure to do it outside, or they could get back into your living space.

You may also consider using a flea spray on your carpets and upholstered furniture. Be sure to keep your pets and your family away from sprayed areas until they’ve dried. Having fleas in teh home doesn't mean your house is dirty or that you are a bad pet owner. Fleas are attracted to food sources, which is any pet cat or dog.

Step 3: Ease the itch. Your pet’s veterinarian will recommend a topical, oral, or injected medication to ease your pet’s itching and inflammation. If your dog or cat has an infection, the veterinarian may also prescribe an antibiotic or antifungal medicine.
You may have heard that human antihistamines can treat pet allergies. The trouble is, they’re often not strong enough to ease inflammation for many pets with a flea allergy, and they don’t work at all for many animals. Talk to your vet before using them for your pet to determine the best solution and dosage if so.
At home, one of the easiest ways to help ease your dog or cat’s irritation is to give them a bath with cool water. Unless your pet hates water, this can help by making their skin feel better and removing some fleas.

Step 4: Avoid irritants. Don’t use flea shampoo or other topical flea products without talking to your pet’s veterinarian first. Flea shampoos and sprays can contain alcohol and other chemicals that can make a rash or open wounds worse!
You may have seen onion or garlic tablets marketed for pet flea relief, but they can be toxic to dogs and cats. Skip essential oils and products that contain them, too. This can cause further irritation to your pet's skin.

Step 5: Stay in touch with your pet’s veterinarian. Regular checkups are especially important for spotting infection and making sure your flea and allergy treatment plans are working.
If you have a question between scheduled visits, don’t hesitate to call your vet! It is always better to be safe than sorry. The longer something is put off because it doesn't seem serious, could end up something far worse while waiting. Early detection and treatment is of utmost importance.

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What Pet Owners Should Know About Food Allergies

You've heard it before. Limited Ingredient Diets. Grain-Free. Allergen-Free. Animal byproduct free. The majority of these companies suggest that these dog food formulas may be helpful for pets with allergies. How true are these claims, though?

As it turns out, food allergies are not as common as many pet food companies and websites may like for you to think. And while food allergies are one possible cause for your dog’s itchy skin, ear infections, or your cat’s diarrhea—there are many more likely causes which may have nothing to do with the food

What is a food allergy?

Food allergies occur when an animal’s immune system misidentifies a protein from an ingredient in their food as an invader rather than a food item and mounts an immune response. The end result of this response can be itchy skin or ear and skin infections in some pets, while it may cause vomiting or diarrhea in others. Some unlucky pets will have both skin and gastrointestinal symptoms. However, food allergies have to be distinguished from numerous other more common causes of these issues.

What are other causes of gastrointestinal signs in dogs and cats?

There are dozens of causes of gastrointestinal issues in dogs and cats – parasites, viruses, bacterial infections, pancreatitis, eating something they shouldn’t, and many others. For pets that have symptoms only on certain diets, it could be due to a food allergy, but it could also be due to an intolerance. For instance, the food may have too much fat, too much or too little fiber, or have other properties or ingredients that don’t agree with that particular pet but aren’t due to an allergy. An appointment with your veterinarian will help narrow down the issue(s) at hand.

What are other causes of itching, and skin and ear infections?

The most common cause of itching, skin infections, and ear infections in both dogs and cats are fleas, allergies to fleas, and environmental allergies – dust mites, pollen, grasses. Both flea allergies and environmental allergies are MUCH more common in pets than food allergies but flea, environmental, and food allergies can all have similar symptoms.

Diagnosis of food allergies

One of the most frustrating things about food allergies is that there really isn’t an easy test. While many tests – using blood, saliva, and even hair – that can be performed by your veterinarian or purchased by a pet owner online (and even sometimes shockingly, through a Groupon!) advertise that they can diagnose food allergies or “sensitivities”, there is no proof that they work. None of the currently available tests have been shown to be accurate – that non-allergic dogs test negative and allergic dogs (and only allergic dogs) test positive. In fact, multiple studies have shown that these kinds of tests are not very helpful in diagnosing food allergies, despite their widespread use for this purpose. Research results presented at a veterinary dermatology conference even showed that some tests “diagnosed” plain water and stuffed animal “fur” as having food allergies.

The “gold standard” or best method that we currently have, for diagnosing food allergies is the dietary elimination trial. This means feeding your pet a diet purchased through a veterinarian or carefully made at home that contains only a few ingredients (typically one protein and one carbohydrate plus necessary fats, vitamins, and minerals) that your pet has never been fed before or that are hydrolyzed (where the proteins are broken down into very small pieces that can hide from the immune system) or purified to remove the parts that are likely to cause allergies. This diet is then fed as the only food or flavored thing to go into your pet's mouth for a minimum of a month or more, depending on your pet's medical history and issues. If your pet’s signs dramatically improve during the trial, then to confirm a food allergy, your pet then has to go back to the old diet again. A quick relapse is suggestive of an allergy to an ingredient in the old diet. You then go back to the test diet until things get better again before trying one ingredient from the old diet at a time until you identify the specific foods that trigger the problem. Many people switch diets and their pets’ signs improve, but they never re-challenge, so we can’t know if it was coincidence or the diet that actually helped the pet! We see this commonly when the seasons change – pet owners assume it was the diet that caused the improvement in their pet’s allergies when actually it is because seasonal allergens – such as certain pollens – are much reduced.

The “allergy diet” myth

There are no diets that are completely “hypoallergenic”, meaning that they will not cause allergies. The closest we have to this kind of a diet are the hydrolyzed diets that can be purchased through veterinarians. Dogs and cats can be allergic to pretty much any protein or carbohydrate ingredient that can be found in pet food. Feeding a diet with duck, kangaroo, lamb, or venison doesn’t prevent food allergies, it just makes it likely that if your pet develops one, it will be to that protein instead of something more common like pork or chicken. Likewise, there is no evidence that continually changing (rotating) diet ingredients prevents food allergies, but it definitely can limit diet choices to try to diagnose them (since every ingredient your pet has eaten before is no longer available to be used in a dietary elimination trial).

What foods are associated with the most allergies in pets?

While the overall percentage of dogs and cats that have food allergies is low, there are some ingredients that are associated with more of the confirmed cases than others. The most commonly reported food allergies in dogs and cats are chicken, beef, dairy, and egg (and fish for cats). There is nothing particularly special about these ingredients other than they have been the most common ingredients in pet foods for the past few decades, so both cats and dogs often have been exposed to them a lot. What surprises many pet owners is that grains are actually uncommon causes of food allergies – most pets are allergic to animal proteins! Yes, the occasional pet is allergic to a specific grain, or even another plant-sourced ingredient such as potato, or even carrot, but this is less common than an allergy to an animal protein. Unfortunately, this information doesn’t prevent hundreds of companies from advertising their grain-free diets as being good for pets with allergies. Many companies also advertise gluten-free diets for pets. Gluten allergies seem to be extremely rare in pets, having been clearly documented only in Irish Setter dogs, possibly in Border Terrier dogs, and never in cats.

Do I have to use a diet from my vet for a diet trial?

Many companies make over-the-counter diets that they market as being good for dogs with allergies, but they often don’t live up to the hype. Many of these so-called “limited ingredient diets” contain more than 1 protein and 1 carbohydrate source. They may contain fruits and vegetables, alfalfa, kelp, or other ingredients that could interfere with a diet trial. Even those that only have 1 protein and 1 carbohydrate as well as the necessary vitamins and minerals listed on the bag may still contaminated with other ingredients. Several studies recently have shown that large proportions of over-the-counter diets contain ingredients (admittedly sometimes in very small amounts) not listed on the label, likely due at least in part to the common industry practice of running one diet after another in the same manufacturing line at the factory, without a thorough cleaning in between (this is like human foods that are labeled as being made in a factory that also processes nuts – even though they don’t contain nuts, they could have nut residues). Because of the high risk of contamination for over-the-counter diets, we strongly recommend using a veterinary diet for your dietary elimination trial (either novel ingredient or hydrolyzed, depending on the individual pet) or a carefully prepared home-cooked diet designed by a board-certified veterinary nutritionist. The best diets for a food trial have 2-3 ingredients plus fat sources (which are very low risk for allergies) and supplements. Diets for a diet trial should never include fruits and vegetables (unless a vegetable like a potato is one of the 2-3 ingredients), herbs, or ingredients such as kelp because they can make it hard to interpret the results if your pet doesn’t improve on the diet.

If your veterinarian diagnoses a food allergy using a dietary elimination trial with a veterinary diet or home-cooked diet, you may be able to manage your pet afterward with specific over-the-counter diets (once the specific allergen is identified), keeping in mind that you could see a flare-up if you unknowingly purchase a contaminated bag.

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