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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What Can I Catch From My Cat?

Although most feline infectious diseases only affect cats, some of these diseases can be transmitted from cats to people. Diseases that can be transmitted from animals to people are called zoonotic diseases. While not comprehensive, this article highlights the most common zoonotic diseases that may be carried by cats and simple precautions you can take to reduce your risk of contracting these diseases. For more information about specific risks, diagnosis, and treatment of zoonotic diseases, contact your physician/health professional.

What's the risk?

The likelihood of an average person contracting a zoonotic disease from a cat is low, but individuals with immature or weakened immune systems are more susceptible to these diseases. This includes infants, individuals with acquired immunodeficiency syndrome (AIDS), the elderly, and people undergoing cancer chemotherapy or receiving other drugs that may suppress their immune systems.

Common Feline Zoonotic Diseases

Bacterial Infections

Cat scratch disease (CSD) is caused by a bacterium called Bartonella henselae, which may be carried in the saliva of infected cats and in the bodies of cat fleas. As the name implies, this bacterial infection is usually transmitted from cat to human via scratches, although it can also be transmitted via bite wounds and when a cat licks the open wounds of a person. Among cats, this bacterium is most commonly transmitted by the bites of infected cat fleas, and it may also be found in the feces of these fleas, which can serve as sources of infection if exposed to an open wound in either a cat or a human.

People with CSD usually develop swelling and possibly a blister at the site of the bite or scratch. Lymph nodes in the region of the wound may swell and become painful, and affected individuals may experience fever, headache, sore muscles and joints, fatigue, and poor appetite. Healthy adults generally recover with no lasting effects, but it may take several months for the disease to go away completely. People with compromised immune systems may suffer more severe consequences, including infections of the eyes, brain, and heart. Severe cases of CSD may require antibiotic therapy to resolve.

Approximately 40 percent of cats are infected with Bartonella henselae, but most show no signs of disease. Antibiotics do not reliably cure infection in these cats and are not currently recommended. For humans, avoiding scratches and bites (for example, by not allowing children to play roughly with cats), washing hands after playing with cats, controlling fleas, and keeping cats indoors all reduce the risk of CSD. Because most cases of CSD result from contact with kittens under one year of age, immunocompromised people should avoid such contact.

Pasteurella multocida is a bacterium found in the mouths of between 70 and 90 percent of cats, and it has been found in between 50 and 80 percent of cat bites in humans that become serious enough to seek medical attention. Cat bites infected with this organism may develop pain, swelling, and redness at the wound site within 24 to 48 hours. Pasteurella-infected cat bite wounds are successfully treated with antibiotic therapy in the vast majority of cases, but more serious complications, such as the spread of bacteria through the blood stream and infection of heart valves, may occur in rare cases.

Salmonella poisoning, also called salmonellosis, is caused by a group of bacteria called Salmonella, and can lead to diarrhea, fever, and stomach pain beginning one to three days after infection. People usually contract salmonellosis by eating contaminated food, such as undercooked chicken or eggs, but it is possible to contract the disease from infected cats, which can carry Salmonella bacteria and pass them in their stool. Although salmonellosis usually resolves on its own, some individuals require medical attention to address severe diarrhea or the effects of the infection on organs other than the digestive tract.

Salmonella is more commonly found in cats that feed on raw meat or wild birds and animals, so owners can reduce the risk of salmonellosis in themselves and their cats by keeping cats indoors and feeding them cooked or commercially processed food. Wearing gloves when cleaning litterboxes or gardening (in case outdoor cats have defecated in the soil) and washing hands thoroughly after these activities is also recommended.

Parasitic Infections

Fleas are the most common external parasite of cats, and their bites can cause itching and inflammation in humans and cats alike. Fleas may also serve as vectors for CSD and other zoonotic diseases. Flea-infested cats may become infected with tapeworms from fleas ingested while grooming. While not common, people can also become infected with tapeworms by inadvertently ingesting fleas.

Scabies, or infection by the mange mite Sarcoptes scabiei, is another zoonotic external parasite of the skin of cats. While not as common as flea infestations, these mites can be passed from infected cats to people, where they burrow into the skin and cause itchy, raised lesions. Treatment in people usually involves the use of topical ointments to decrease itching, diligent treatment of infective pets, and careful cleaning of clothes and bedding.

Certain feline intestinal parasites, including roundworms (Toxocara) and hookworms (Ancylostoma), can also cause disease in people. Children are particularly at risk due to their higher likelihood of contact with soil that has been contaminated by cat feces. Although most people infected with feline intestinal parasites do not show signs of illness, some people may get sick.

Visceral larva migrans, a potentially serious disease that can affect various organs, results from consumption of Toxocara eggs (for instance, when soiled fingers are placed in the mouth). Toxocara larvae may then migrate to abdominal organs, including the liver, or to the central nervous system. Symptoms of visceral larva migrans may include fever, fatigue, coughing, wheezing, and abdominal pain. Ocular larva migrans is the term used for a condition in which Toxocara larvae migrate to the eye, causing visual disturbances, abnormal eye movements, or eye pain and discomfort.

Cutaneous larva migrans, an itchy skin disease, is caused by contact with soil contaminated with Ancylostoma larvae. These larvae may penetrate and migrate under the skin, with resultant inflammation, itching and pain, and raised, red linear lesions in the skin that follow the larva’s migration. Proper hygiene, including washing hands before meals, cleaning soil from vegetables, and reducing exposure to cat feces can prevent infection. Anti-parasite medications for kittens and annual fecal exams for adult cats can reduce environmental contamination and the risk of human infection.

Fungal Infections

Ringworm (or dermatophytosis) is not caused by a worm at all. Rather, it is a skin infection caused by a group of fungi. Infected cats most often come from environments housing large numbers of animals. In cats, ringworm usually appears as a dry, gray, scaly patch on the skin. In humans, ringworm often appears as a round, red, itchy lesion with a ring of scale around the edge. Lesions may be found in a variety of places, including the scalp, the feet (where’s its referred to as “athlete’s foot”), the groin, or the beard. Ringworm is transmitted by contact with an infected animal’s skin or fur, either directly or from a contaminated environment. Infected cats continuously drop fungal spores from their skin and fur. These spores, which remain capable of causing infection for many months, are difficult to eradicate from a household. Children are particularly at risk of infection. Treatment involves the use of either topical antifungal ointments or oral antifungal medication, depending upon the severity and location of lesions. To reduce environmental contamination, confine infected cats to one room until they are free of infection, then thoroughly clean and disinfect the household.

Protozoal Infections

Protozoans are single-celled organisms. The three most common protozoal diseases in cats and humans are cryptosporidiosis, giardiasis, and toxoplasmosis.

Cryptosporidiosis can cause diarrhea, vomiting, fever, abdominal cramps, and dehydration in both cats and people. Either direct or indirect contact with the feces of cats infected with Cryptosporidium organisms can lead to transmission of this disease. As with most other zoonotic diseases, immunocompromised individuals are at the greatest risk of infection. To prevent the spread of infection, schedule annual fecal examinations for your cats, and medicate infected cats as directed by your veterinarian. Other preventive measures include wearing gloves while handling feces-contaminated material and washing hands afterwards.

Giardiasis is caused by infection with the microscopic parasite Giardia. Many animal species (including the cat), are susceptible to infection with Giardia, which is passed in the feces and usually spread to other animals and humans via contaminated water sources, surfaces, or in uncooked food items. The symptoms of Giardia infection include diarrhea, flatulence, abdominal cramps, nausea, and dehydration. A number of prescription drugs are available to treat this condition, and most people that are infected make an uneventful recovery. It is important to realize that the majority of cases of giardiasis in people do not occur as a result of infection by cats, but rather by ingesting water or food contaminated by farm animals or wildlife.

Toxoplasmosis is caused by the parasitic protozoan Toxoplasma gondii. People with weakened immune systems and infants whose mothers are infected during pregnancy can develop severe illness from this parasite. Most people infected with Toxoplasma, however, show no overt signs of disease.

Cats can acquire Toxoplasma by eating infected rodents, birds, or anything contaminated with feces from another infected animal. An infected cat can shed the parasite in its feces for up to two weeks. Once shed in the feces, the parasite must mature for one to five days before it becomes capable of causing infection. However, it can persist in the environment for many months and continue to contaminate soil, water, gardens, sandboxes, or any place where an infected cat has defecated. Although pregnant women or immunosuppressed individuals are often advised to remove cats from the household to reduce the risk of toxoplasmosis, direct contact with cats is very unlikely to spread infection with this organism.

Cats can transmit Toxoplasma to people through their feces, but humans most commonly become infected by eating undercooked or raw meat, or by inadvertently consuming contaminated soil on unwashed or undercooked vegetables. The symptoms of toxoplasmosis include flu-like muscle aches and fever, and headache. In rare cases, more advanced symptoms such as confusion, seizures, vomiting, or diarrhea may be observed.

Basic hygiene can prevent the spread of Toxoplasma from cats to humans. Wear gloves when handling potentially contaminated material (for example, when gardening or scooping the litterbox), and be sure to wash your hands afterwards. Cover children’s sandboxes when not in use to prevent wandering cats from defecating in them.

Pregnant women or immunosuppressed individuals are safest when other household members clean the litter box.

Viral Infections

Rabies is a viral disease that is spread through the bite of an infected animal. Although most viruses infect only their natural host species, rabies is an important exception. Cats are highly susceptible to rabies, which attacks the central nervous system, causing a variety of signs. Rabies is almost always fatal. In people, rabies infections usually occur when an infected animal bites a person. In order to protect human health, rabies vaccination of cats is required by law in many areas. Even if your cat is kept indoors, it is important to keep rabies vaccines current because cats occasionally escape outdoors, and because rabid animals such as bats and raccoons occasionally enter houses. To further reduce your risk of rabies, avoid contact with wildlife and stray animals and see a doctor immediately if you have been bitten by an animal.

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