Fungal Infection in Dogs - Systemic and Localized Infections

We cannot list every type of fungus that can affect a dog because there are too many to list. It is important to know there are two main types since these will result in very different symptomologies. They are:

• Systemic fungal infection in dogs: a systemic fungal infection is one which affects the internal tissues of the dog's organism. Whether they have been inhaled, ingested or entered their body from any orifice, fungal infections can occur in the lungs, stomach or even the blood^[1]. When the fungal pathogen enters the blood, it can easily spread to other areas of their body. They can even occur due to an overproliferation of fungi that are normally present as part of a dog's microbiota.
  
  
• Localized fungal infection: this is what happens when your dog develops a fungus on a specific part of their body, usually their skin. Localized fungal infections are usually external. They are the most common type of fungal infection in dogs and we can directly observe them on the dog's skin. This is in contrast to systemic fungal infections which usually reveal themselves in other symptoms. Localized fungal infections can also affect internal tissues such as the mucus membranes or intestines.

We will better understand these types of canine fungal infections in the next sections.

When a dog has a fungal infection that is affecting internal tissues of their body, the symptoms are more generalized at the beginning. This makes it difficult to determine whether the issue is a fungal infection or another health problem. For example, when a dog is coughing, it could be as a result of a viral or bacterial infection, as well as underlying health problems such as congestive heart failure. It will usually not be until a veterinarian confirms the diagnosis that we know they have a systemic fungal infection.

Types of systemic fungal infections in dogs include:

• Aspergillosis: although this can be localized, disseminated aspergillosis in dogs can provide a systemic infection. Caused by fungi from the genus Aspergillus, it travels through the bloodstream to various other organs and tissues. Unfortunately, this disease can progress without symptoms for a long time and once symptoms such as coughing, fever, lethargy or jaundice occur, it could be in a very advanced state.
  
  
• Coccidioidomycosis: also known as valley fever due to its prevalence in dry desert areas of the US. It usually affects the lungs, but can spread throughout the body. Symptoms may not occur, but if they do it can lead t coughing, weight loss and depression. Once systemic, it can affect other organs and result in organ failure.
  
  
• Cryptococcosis: caused by fungi from the Cryptococcus genus, this is a very serious fungal infection in dogs that can spread easily. It can be inhaled or enter the body through other orifices or wounds. As with all fungal diseases, dogs which are immunosuppressed are more likely to develop in infection due to a weakened immune system.
  
  
• Histoplasmosis: this fungus often develops on the top of soil, with dogs inhaling it into their lungs when they sniff the ground. It can spread to other organs after entering the bloodstream through the lungs. Symptoms depend on the extent of the fungal infection and the organs affected. For example, jaundice in dogs can occur when liver failure is a result.

Similar fungal infections in dogs can result in systematic diseases such as sporotrichosis and phaeohyphomycosis can also occur. These diseases generally begin as being localized to areas such as the nasal passages or lungs, before spreading out to the rest of the body when they become systemic.

Systemic fungal infections also usually take time to progress. For this reason, the dog may be asymptomatic at the beginning, but then

We have already discussed how localized internal fungal infections can affect dogs. Localized external fungal infections will depend on the area affected. For example, if we see a dog keeps chewing their paws, it could be due to an interdigital fungal infection.

Different types of dog skin fungus can cause infection. Some of the most common types of skin fungus in dogs are:

• Yeast dermatitis: caused by the fungus Malassezia pachydermatis, it is one of the most common causes of skin dermatitis in dogs. Learn more with our article on malassezia in dogs.
  
  
• Ringworm: despite its name this is not a parasite, but a type of fungal infection which causes a ring-shaped lesion to appear on the skin. It is caused by various species of fungi.

As the fungal infection progresses, the skin will become inflamed and itchy. This is known as fungal dermatitis and it can result in the skin breaking, making the dog susceptible to secondary bacterial infections. When the fungal infection is not treated, the itching and frustration they cause can result in the dog becoming agitated or even depressed.

Some of the main symptoms of skin fungus in dogs include the following:

• Constant itching
• Hair loss
• Skin flaking
• Skin inflammation
• Reddening of the skin
• Wounds
• Nail injuries
• Bad odor
• Anxiety or depression

Some fungal infections have more specific symptoms. For example, a common symptom of a fungal yeast infection on their feet can cause a dog's paws to smell like Fritos. If we observe any of these symptoms, we need to take them to a veterinarian for diagnosis and treatment administration.

Once we take the dog to the veterinarian, they will run diagnostic tests. After a visual inspection of the lesions, the veterinarian might use something known as a wood lamp. This is a special UV radiating lamp which comes with a wood filter. It is designed to inspect skin for mites as well as bacterial or fungal infection^[2]. This will help locate the areas which need to be inspected further. Once the spot is located, lesion samples can be taken.

The samples are always taken from the peripheral area of the lesion. If the dog has many lesions, the sample is usually taken from the newer ones or the ones which seem to be in the greatest state of infection. In general, the oldest ones are most contaminated with other pathogens. They will likely clean the lesion with disinfectant before taking a sample so that they can get to the root of the infection.

The samples are of either skin, nails or hair. However, hair and skin are the most common types of sample taken. The hairs are usually plucked to achieve a proper diagnosis, not cut as they will not have the full extent of the infection. The peripheral area of a skin legion is better than the center as it will not be properly representative.

Once the sample has been appropriately obtained by the veterinarian, there are a few procedures used to achieve a diagnosis. Direct examination under a microscope is possible, but not the ideal as it can unfortunately achieve doubts and false positives. The most used method is to create a culture. They are the most accurate methods of diagnosis and can be used to see which antibiotics might be resistant to a particular fungus. Usually, however, this method involves sending the sample to a laboratory as the vet may not have the right equipment to analyze it in their clinic.

We have discussed above the importance of taking a dog with a suspected fungal infection to the vet where and accurate diagnosis can be made. However, before you have the chance to take them to the vet and you suspect a fungal infection, there are some tips which may prevent the situation from worsening:

• Do not bathe the dog too often as this can create an ideal environment for the fungus to proliferate. This may seem counterintuitive as their skin looks dirty, but you can wipe this dirt away instead if you are worried.
  
  
• Keep infected dogs away from other animals or members of the family home. This is because the fungus can spread. Especially refrain from letting the dog sleep in the same place together.
  
  
• There are fungi which can be transferred to humans (such as ringworm) so be hyper-vigilant and ensure to wash your hands with antibacterial soap every time you touch them.
  
  
• If you travel by car or have any communal areas where the dog might sit, ensure you lay down a blanket or protector and wash after use.

There are different types of treatment for fungal infections in dogs, both conventional allopathic treatment and home remedies. However, always go with the recommendation of a trusted vet as their expertise and experience will take precedence. Here we will take a look at some of the options available:

• Allopathic treatment: the main medical treatment of fungal infections in dogs include antifungal medications, antibiotics or a mixture of both. These can be topical applications which are found in ointments or lotions for localized dog skin fungus. Oral antifungal medications can be used for systemic infections. Antibiotic medicine will be administered if there are secondary bacterial infections. One of the most common antifungal medications is itraconazole for dogs which can be used for aspergillosis, coccidioidomycosis, histoplasmosis and others.
  
  
• Homeopathic treatment: there are some homeopathic treatments or home remedies available for fungal infections in dogs. The idea for most of them is that they will bring balance to your dog. Their effectiveness is not often backed up with conclusive scientific evidence and are certainly not recommended in extreme cases of infection.
  
  
• Healthy eating: in minor cases of fungal infection in dogs, it is possible that a change of diet can help them to build up their immune system and fight the infection this way. However, this will risk spread of the infection and are likely to prolong its length. It is better to include this in conjunction with more effective therapies as a means to help stave off other infections in the future.

If your dog does have a fungal infection, it is vital you do not give antifungal medication without veterinary prescription. The vet needs to determine the type of dog skin fungus or systemic fungus and provide the appropriate treatment. Giving the wrong kind can mean the fungus is not being treated or even worsen the clinical picture.

it is important to not only treat the condition, but ensure prevention of it coming back. This means minimizing the areas the dog stays in (although still allowing for exercise), keeping them away from other animals and not letting them spread the fungus to other areas. Thoroughly wash, properly dispose of or destroy blankets and fabrics with which the dog comes in contact.

Preventing your dog from having a relapse of fungal infection is important, but protecting the spread of this fungus is important for other reasons. Not all disease from which a dog suffers can be passed on to humans, but some fungal infections can be one of them. They can also be passed on to other dogs as well as animals of a different species such as cats or guinea pigs.

Not all fungal infections can spread to humans. Ringworm is one of the most common that can, but it will depend on how we interact with the dog.

Cross contamination of fungal infections can occur from direct contact, but also through peeled skin or infected pieces of fur. Ensuring your dog has limited contact throughout the treatment of the infection is important as it will help maintain the health of the rest of your family members.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Fungal Infection in Dogs - Systemic and Localized Infections, we recommend you visit our Bacterial diseases category.