Fungal Infections Seen in Dogs

Fungal Infections Seen in Dogs

Health & Safety

The most common fungal infection seen in dogs and which most people are familiar with is ringworm. It's a very contagious condition that needs immediate and careful treatment or the infection may take hold and spread to other animals and people. However, there are quite a few other fungal infections that can affect dogs in different ways making them very ill. Fungal infections are quite different from bacterial infections and more often than not, they can be extremely difficult to treat.

The majority of standard antibiotics are not effective on certain types of fungal infections which often leads to severe infections that may attack any part of a dog's body. The only good news is the fungal infections are rarely very contagious with the exception being ringworm.

The Most Common Fungal Infection Seen in Dogs

As previously mentioned, ringworm is the most common fungal infection seen in dogs and is a skin disease that's caused by four different forms of fungus. The visible signs of ringworm are hairless round, extremely itchy lesions that become very sore and inflamed if left untreated. You need to be very careful when treating a dog (or other animal) that's suffering from the condition as you could catch it by touching the lesions. These days there are some very effective topical preparations available to treat ringworm, but if you are worried about your dog's condition, you should discuss it with your vet as soon as you can.

What is a Systemic Fungal Infection?

A systemic infection means it's a condition that affects the whole body, therefore a fungal infection that's diagnosed as systemic may affect a dog's entire body attacking the eyes, lungs, organs and bones. A fungal infections like Blastomycosis, is more commonly seen in dogs that live close to water and spend a lot of the time in it – namely retrievers. Around 40% of dogs that suffer from Blastomycosis have painful eye lesions with 85% of them suffering lung lesions. The other commonly symptom being small skin lesions that look very similar to abscesses which can be found anywhere on the body.


Another fungal disease affecting dogs and which can be a serious health issue if left untreated is Coccidiomycetes. The problem vets have with diagnosing this condition is that it can show up on x-rays as being cancer. For this reason it vitally important for a dog that's suspected of suffering from the condition, to see a vet as soon as possible for them to carry out in-depth tests to rule out cancer and then start an effective treatment for the fungal infection.

Other fungal infections to watch out for and which can seriously affect the health and well being of your dog are as follows:

  • Histoplasmosis
  • Malassezia Infection
  • Cryptococcal Infection


Histoplasmosis is a nasty fungal infection that affects a dog's lungs where it first takes hold after a dog has come into contact with contaminated ground or ingested bird or even bat droppings. It's usually seen in dogs that spend a lot of time outdoors, although “indoor” pets can get the disease too, and it's thought this happens if they come into contact with any manure that's been contaminated - this could include potting soil. However, it is usually more likely the dog picked it up from roaming in an area where there are lots of bird droppings, whether pigeon, poultry or even bat droppings (guano).


Malassezia is a yeast infection found both on a dog's skin and on their ears. It's perfectly normal for yeast to be present, however, when there is an “overgrowth” of yeast, it leads to dermatitis or an inflammation of the affected area. No one actually knows what causes the condition but it's thought to a congenital disorder although the jury is still out on this with some people thinking it could be connected to an allergy or that hormonal factors may come into play.

Malassezia infections cause a nasty skin irritations which can be quite smelly. The dog's skin becomes greasy turning red or even black. The skin is sore and very itchy which causes dogs with the condition a lot of discomfort, the more it irritates the dog and the more they scratch at it, which is a vicious circle.

Although all dogs can be affected by Malassezia, some breeds appear to be more predisposed to it than others which includes the following:

  • Poodles
  • Basset hounds
  • West HighlandsWhite terriers
  • Cocker spaniels
  • Dachshunds


Although Cryptococcal infections are more commonly seen in cats than dogs, they can still contract it and if left untreated can cause serious health problems. The symptoms to watch out for include the following:

  • Skin lesions
  • Ataxia
  • Seizures
  • Circling
  • Sneezing
  • Blindness

Luckily, this particular fungal infections is very rarely seen in the UK and is more commonly found in North America. However, all breeds of dogs anywhere in the world may contract Cryptococcosis with this particular fungal infection affecting their respiratory tract, more especially their nasal cavities, their eyes, skin and central nervous systems. Dogs pick it by from bird droppings when they either inhale the fungal spores or ingest the droppings. It is a systemic disease that needs to be diagnosed early and treated as soon as possible. Failure to have a diagnose made early could mean the infection spreads to the central nervous system and then the outlook for recovery is extremely poor.


If you are at all worried your dog may have been exposed to any harmful fungal spores and if they are showing any of the symptoms mentioned above, you should seek advice from your vet as soon as you possibly can. They will be able to carry out a thorough physical examination of your dog, take the necessary blood samples and other tests to determine whether your dog has indeed been infected and then recommend the right kind of treatment for them. For your dog to make a full recovery, the after care you offer them is very important when dealing with a fungal infection. Very often it means you may need to limit the amount of exercise you give your dog and you may have to take them back to the vet for regular check-ups until they have made a full recovery.

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