How do I know if my dog has a fungal or bacterial infection
Identifying and Treating Fungal Infections in Dogs
By Reyna Gobel
Bacteria and viruses are what typically spring to mind hen pet parents think infection, but fungi can also be to blame. While not as common as bacterial or viral infections, fungal infections can be just as serious. Dogs can contract fungal infections from other animals, from the environment, or as a result of the overgrowth of fungi that are naturally present on their own bodies. Every pet is potentially at risk for contracting a fungal infection, and an accurate diagnosis is necessary before appropriate treatment can begin. Read on to learn more about fungal infections in dogs.
Fungal Skin Infections
When your dog starts scratching himself more than is normal, it can be hard to tell whether its because of an allergy, flea bites, infection, or something else. Excessive itching can be quite worrisome, especially if your dog develops bald spots or damages his own skin as a result.
One telltale sign of fleas is the presence of flea dirt (small black clumps of flea feces) on your dogs skin and fur. If you see flea dirt or actual fleas, treat him right away. But if fleas or ticks arent to blame, dont self-diagnose or rely on Dr. Google, warns Dr. John DaJong, a veterinarian at Newton Animal Hospital in Massachusetts. After performing a complete physical exam, your veterinarian can conduct specific tests to help diagnose the problem and identify whether a fungal infection is to blame.
Lets look at two common types of fungal infections that affect the skin of dogs and how to treat them.
Ringworm
Ringworm is a common fungal infection in pets. It can affect a dogs skin, fur, and also the nails. Common symptoms include hair loss, itching, flaky or crusty skin, and misshapen or brittle nails. While you should treat any infection as soon as possible, time is of the essence with ringworm because it can easily spread to other household animals and humans, says Dr. Andrew Rosenberg, a veterinarian at Riverdale Veterinary Dermatology clinic in Riverdale, New Jersey.
To diagnose ringworm, your veterinarian will perform a fungal culture of hair or skin cells or a microscopic examination of a hair sample. Depending on the severity of the infection, ringworm may be treated with medicated baths and dips and/or oral antifungal medications. Vacuuming and disinfecting the house will also help lessen the chances that ringworm will spread between pets and people.
Yeast Infection
Overgrowth of yeast on a dogs body can lead to irritating yeast infections, commonly affecting the skin, paws, and ears. These infections can be extremely uncomfortable for dogs, says Rosenberg. Theyre generally secondary to allergies or other conditions that disrupt the skins ability to control the yeast that normally live there.
If I suspect a dog might have a yeast infection, I take an impression smear of the area that might be infected and look at it under a microscope, Rosenberg says. When the slide is stained, the yeast look like little purple peanuts.
Treatment normally involves an antiseptic or antifungal drug applied to the skin. Oral medications may be necessary in severe cases. Unlike ringworm, yeast infections arent contagious to other pets or people. To prevent yeast infections from recurring, its important to treat any underlying conditions as recommended by your veterinarian.
If your pet is constantly itching and scratching, schedule an appointment with your veterinarian. Unfortunately, not all conditions can be solved with one visit. Sometimes it could take several visits to pinpoint the cause of your dogs itching or require a visit to a veterinary dermatologist, Rosenberg says.
Systemic Fungal Infections
Fungal infections on the surface of the body are bad enough, but those that invade deeper structures can have even more serious consequences. Lets look at several common types of systemic fungal infections in dogs and how to treat them.
Blastomycosis
Blastomycosis is most commonly diagnosed in dogs that have spent time in Mississippi, Ohio, Missouri, Tennessee, the St. Lawrence River valley, the mid-Atlantic, and around the Great Lakes because the types of soil that are typically found in these areas support the growth of the fungus. Dogs that spend time sniffing around in the dirt are at risk for inhaling fungal spores, which can lead to a lung infection, says Dr. Jennifer Coates, veterinarian and author of Dictionary of Veterinary Terms, Vet-Speak Deciphered for the Non-Veterinarian. From there, the organism can travel almost anywhere in the body. According to Coates, common symptoms include poor appetite, weight loss, coughing, difficulty breathing, limping, eye problems, skin lesions (particularly around the toenails), enlarged lymph nodes, and fever. If the disease is caught early enough, treatment with an oral anti-fungal medication can be curative.
Cryptococcosis
While cats are more commonly infected with the fungus Cryptococcus, Coates says dogs tend to develop a more severe form of the disease. The fungus is present in soils world-wide but may be especially prevalent in areas where pigeons and other birds congregate. As is the case with blastomycosis, dogs typically inhale the Cryptococcus fungus, leading to a lung infection. It can then spread almost anywhere in the body, which can cause symptoms ranging from lethargy, coughing, nasal discharge, eye problems, skin lesions, and even seizures and other neurologic abnormalities. Coates warns that treating cryptococosis can be difficult. Oral antifungal medications may need to be given for a year or more and some dogs will still succumb to the disease.
Coccidioidomycosis
Dogs can get coccidioidomycosis (also known as Valley Fever) from inhaling dust or dirt that contains coccidioides fungal spores,says Dr. Carol Hillhouse, a veterinarian in Panhandle, Texas. It tends to grow in desert areas with little rain and sandy soil, such as California, Nevada, Arizona, New Mexico, and Texas, she says. Strong winds, earthquakes, construction areas, and even crop harvesting can stir up the spores into the air.
Once the spores are inhaled, the fungus may simply cause a chronic cough, Hillhouse says. In other cases, especially if immunosuppressed, the dog may develop pneumonia or the fungus can spread to other areas in the body, such as bone or the eyes, she says. It can be difficult to diagnose, and usually requires radiographs, blood, and cell testing. Valley fever requires long-term treatment with oral antifungal medications, but the prognosis is pretty good if caught early, she says.
Histoplasmosis
Another soil-borne fungus, Histoplasma, prefers the temperate climates of Ohio, Mississippi, and Missouri River Valleys, Hillhouse says. This fungus grows best in nitrogen-rich soil, such as bird and bat excrement, and is usually acquired by inhalation of the organism from the environment.Infected dogs can show weight loss, fever, cough, eye inflammation, vomiting, and diarrhea, she says. Often, a combination of blood and urine tests, as well as radiographs, are used to make the diagnosis. Sometimes biopsies are required as well. Treatment involves long-term fungal medication, but prevention is best by restricting access to soil that is contaminated with bird or bat droppings.
Aspergillosis
Infections with Aspergillusfungus are usually limited to a dogs nasal passages. Aspergillosis can affect dogs residing in almost any part of the country since the fungus is present in most soils. Treatment typically involves anesthetizing the pet and infusing his nasal passages with a liquid anti-fungal medication. Most dogs will recover if treated appropriately, although a second treatment may be necessary in some cases.
Preventing Fungal Infections in Dogs
Fungal infections in dogs range from localized annoyances to potentially fatal systemic diseases. Prevention is not always possible, but common sense measures can help. If you live in an area where a certain type of fungal infection is endemic, avoid high risk environments. Pets with ringworm should be isolated to limit the spread of the disease to people or other animals. Finally, appropriately manage any underlying health problems that increase your dogs risk for developing a fungal infection.
Dog Bacterial Skin Infections [With Pictures & Vet Advice]
Canine skin disease is a common problem that can affect any breed. Most dog lovers have had some experience caring for dogs with red, itchy skin.While all dogs are vulnerable to canine skin disease, some breeds are more susceptible.
For example, Shar Peis and French Bulldogs are prone to infections in their skin folds. Labradors and Golden Retrievers attract hot spots, while Basset hounds are prime real estate for yeast and bacterial growth.Dermatological problems can be very frustrating.Not only is your pooch uncomfortable, but the necessary treatments can often be prolonged.
Working as a veterinary technician in a busy veterinary hospital, Ive treated many dogs suffering from itchy, painful skin. From what I have seen, the surest path to resolving the problem is to obtain an accurate diagnosis right from the start.
Symptoms of bacterial skin disease
The majority of canine skin infections are bacterial.They are usually secondary to another disease process.Here are some of the main symptoms to watch out for that many indicate bacterial skin infection (also known as pyodermas):
- Redness, pustules, or papules
- Crusty lesions or flaky skin
- Swelling, oozing or draining of a blood-tinged fluid or pus
- Small red bumps
The picture below shows a red, circular lesion that is quite inflamed (staphylococcus bacterial infection). This is sometimes called a bullseye lesion:
With bacterial infections, there is usually inflammation of the hair follicle called folliculitis. This can lead to the build-up of crusts (scabs form). There may be small bumps (papules), raised hairs (tufted papules) and hair loss. Learn more about Folliculitis.
The picture below shows several pustules and inflamed red skin from a bacterial skin infection.
Skin infections can lead to skin irritation that may result in hyperpigmentation and black spots on a dogs skin. As hyperpigmentation results from chronic irritation, these spots will lie flat as part of the skin and will not have a mass-like appearance.
Bacterial skin infections (usually Staphylococcus sp.) cause black spots on the skin in the same manner as injuries, as the infection damages the skins barrier. This damage is a result of the inflammation present secondary to the infection.
When the infection clears in response to treatment, the spots should fade as well. It is normal to see black spots remain much longer after the infection is resolved. The circular sores associated with bacterial infections are referred to as epidermal collarettes. As these sores resolve, the skin becomes hyperpigmented.
Some of these signs are shared by other diseases, like certain immune disorders and neoplasias.Your veterinarian will be able to determine the true cause of the symptoms using their experience and diagnostic tools.
Four Common causes of bacterial skin infections in dogs
Any illness that weakens your dogs immune system increases the chance of a bacterial skin infection. The following interfere with the skins health in a more direct way:
1. Cushings Disease
Cushings Disease decreases the amount of normal collagen found in the skin, causing the skin to become weak and thin with extra folds. The skin may develop dark lesions as well as small raised bumps.Unfortunately, this makes the dog a prime candidate for a secondary bacterial infection.View pictures of dogs with Cushings disease.
2. Hypothyroidism
Hypothyroidism decreases the activity of certain enzymes resulting in changes to the natural skin barriers.The skin develops a darker pigment, there are areas of hair loss and the skin becomes more susceptible to bacterial infection.
3. Flea bite dermatitis
Flea bite dermatitis is an allergic reaction to flea saliva.Your dog will develop itchy skin with hair loss starting on the back and extending to the base of the tail. If left untreated it can progress forward up to the neck and head.Your dogs licking and chewing the itchy skin causes scabs and red bumps, leaving the skin vulnerable to secondary bacterial infection.
4. Sarcoptic scabies and demodex
Sarcoptic scabies and demodex are two parasitic mites that can infect a dogs skin.Demodex is a natural inhabitant of dog skin and only becomes an issue when a dogs immune system is compromised.On the other hand, scabies is spread from dog to dog.
Both of these infections cause great damage to the skin and increase the chance of a bacterial infection setting in.An infection of scabies or demodex is commonly called mange. You will see hair loss and red, scaly skin.
Note: Sarcoptic mange or scabies is contagious to people.
More types and causes of bacterial skin infections
Pyodermas can be classified by the depth of tissue affected. Allergies, immune disorders, and some cancers often underly a bacterial infection.
Surface pyoderma
Only the outermost layer of skin, the epidermis is affected. Hot spots or acute moist dermatitis and skin fold pyoderma are examples of a surface pyoderma.
Hot spots
Canine hot spots are self-induced.When a dog scratches and chews at an itch they may cause small breaks in the skin.As they continue to chew the nerves become inflamed and cause more itching which leads to more chewing.
A hot spot can start as a tiny red spot and very quickly become a large red lesion infected with bacteria. Often they ooze blood-tinged fluid.
The initial itch can be due to fleas, insect bites, allergies, anal sac impaction, or matted fur that pulls at the skin and causes an itch. Additionally, boredom or anxiety can make a dog chew or lick incessantly causing a hot spot.
Skin fold pyoderma (intertrigo)
The friction caused by skin rubbing against skin causes inflammation.The area becomes moist and therefore an ideal place for bacteria to grow.Yeast also likes this environment and is often an additional pathogen (disease-causing organism).
Skin fold pyoderma appears as reddened skin with discharge. There may be a foul odor. The skin folds may need to be spread open to see the inflammation.
Superficial pyoderma
The outer layer of the skin, the epidermis is affected along with the hair follicles.Hair loss, redness, crusty lesions and bumps may be seen.Puppy pyoderma and folliculitis are examples of superficial pyodermas.
Puppy pyoderma
This is one bacterial skin infection that doesnt typically have an underlying disease involved.Puppies skin is sensitive and when it becomes irritated from things in the environment the bacteria that normally live on the surface of a dogs skin cause an infection.
It usually occurs on sparsely haired areas such as the belly, armpits and groin.Puppy pyoderma appears as red bumps or lesions that are sometimes scaly and itchy.
Folliculitis
A common ailment of dogs, folliculitis causes a moth eaten appearance to the hair coat along with redness and itching.Raised red bumps or pustules and flaking, crusty skin may be seen.Sometimes a foul odor may be noticed.Folliculitis is often seen secondary to allergies. View more pictures of folliculitis in dogs.
Deep pyoderma
In deep pyoderma, the deeper levels of the skin, the dermis and the subcutis are affected.This may start as superficial pyoderma and progress to a deep infection. In some cases, a deep pyoderma may arise on its own.Its often secondary to ademodex infection.
Redness, swelling, nodules, or fistulous tracts draining bloody fluid or pus may seen.There may be a foul odor.This is a painful condition, so prompt veterinarian care is necessary.
There are different types of deep pyodermas, including furunculosis and lick granulomas. Furunculosis is when the deep layers of the skin closest to the hair follicles become infected or red and painful nodules are seen. These usually occur in between the toes, around the anus, and on the face.
Also known as acral lick dermatitis, lick granulomas cause a localized lesion that is red, bumpy, and raised.It starts with excessive licking of the same spot.The licking may come from an allergic itch or it could be behavioral.These granulomas usually occur on the wrist, ankles, hocks, or feet.They can become fairly large and unsightly, looking like a tumor.
Diagnosing bacterial skin infections in dogs
Like any disease, obtaining a diagnosis starts with the clinical signs or symptoms. Your veterinarian is familiar with the different types of lesions affecting various areas of the body and this information aids in diagnoses.
But because most skin infections have similar clinical signs, tissue sampling is important.Tissue samples can be obtained via impression smear, skin scraping, or fine needle aspirates.
The samples are examined microscopically and may be submitted for culture and sensitivity testing.Any bacteria cultured is then tested for its sensitivity to various antibiotics.This lets the doctors know which antibiotic will be the most effective for your dog.
Red, itchy skin!Do I need to take my dog to the vet?
Besides the most minor cases, its a good idea to have skin irritations checked by a vet.Skin disease can progress quickly, so its smart to check for any serious diseases that may be the underlying cause.
Here are some reasons your dog needs to be seen by a veterinarian immediately:
- The skin disease is extensive, covering a large portion of your dogs body
- Your dog is showing other signs of illness such as trembling, vomiting, or not eating
- If your dogs skin is bleeding or oozing
Let your vet know the severity of the symptoms so that they will get you in to have your dog seen right away. Untreated skin infections can lead to systemic disease causing serious illness. Moreover, if your dog seems uncomfortable or in pain from constant itching and scratching, you may want to see a vet on an emergency basis to relieve the discomfort.
If the affected area is small and the symptoms are mild, you can try treating your dog on your own with commercial products.There are many shampoos, ointments and all natural remedies for your dogs itchy, inflamed skin. However, its a good idea to consult your veterinarian before using any at home treatment options so that they can recommend ones that are safe and effective.
When attempting a home remedy monitor your dog closely. If the symptoms worsen or there is no improvement after a few days, you need to see a veterinarian.Its imperative to get your dog on the right course of medications quickly to ensure a good outcome.
Treatment options
Surface pyodermas and some superficial pyodermas may resolve with daily bathing using a medicated shampoo prescribed by your veterinarian.
Oral antibiotics are often necessary to cure bacterial skin infections. In addition, medicated shampoos, sprays, or ointments are normally prescribed.It may take three to four weeks to be rid of the infection. Resistant cases may take eight to twelve weeks to cure. As the dog parent you must be diligent, bathing your dog as often as the vet prescribes.
Its necessary for your vet to treat the underlying disease to fully rid your dog of the infection. The cost to treat your dogs pyoderma varies depending on the severity of the infection and how quickly your dog responds to treatment.A mild infection may cost from $200 to $400 to treat.A serious infection could go much higher, costing from $500 to $1000.
These estimates include the exam fee, bloodwork, tissue sampling, cytology (microscopic evaluation of cells), culture and sensitivity, antibiotics, medicated shampoos and sprays.The underlying disease will also need to be addressed and that will involve further diagnostics and medications.
Zoonosis: can I catch my dogs nasty skin infection?
The majority of canine bacterial skin infections are caused by Staphylococcus species, some of which are contagious to people.People with compromised immune systems should use care to not come into contact with the infected dog and the dogs bedding.Healthy individuals should wash hands after handling the dog and perhaps temporarily forgo sharing the bed.
What can I do to prevent a bacterial skin infection in my dog?
Prevention of any disease starts with good nutrition and good hygiene. Regular bathing, keeping their ears clean and wiping skin folds daily goes a long way for skin health. Good grooming, trimming excess hairs of the feet and regular brushing to avoid mats is also important.Keeping up with flea and tick preventative is helpful as well.
Regular exercise helps keep your dog mentally healthy and may keep them from the excessive licking and self mutilation that bored, anxious dogs engage in.
Elana Benasutti is a Certified Veterinary Technician in the state of Pennsylvania. She earned her degree from Harcum College located in Bryn Mawr, Pa. Elana spent her first ten years as a certified technician working as the ultrasound technician in the Radiology Department at the University of Pennsylvanias veterinary teaching hospital, MJR VHUP. Elana spent the next seventeen years as a critical care nurse in the Intensive Care Unit of MJR VHUP.
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