Lethargy, inappetence, cough, fever, fatigue, and more are common signs of most infections or toxicities in dogs. Is it a bacterial or viral infection? Those are fairly common types of infections. Oftentimes we may overlook or forget fungal infections and hope that our dogs will get over it, but that is unwise and could be too late.
In this post, we will run through some of the numerous fungal infections in dogs, and their respective geographical locations, signs, and contagiousness. This is intended to be a checklist of sorts so you can give your veterinarian the complete picture to rule in or out a fungal infection faster.
The argument could be made that fungal infections are underdiagnosed. Vaccines against fungi are not currently available for companion dogs, although some are in development phases.
Aspergillosis
Geographical Location: Worldwide
Cause: Several species of aspergillus
Infection Route: Nasal or respiratory
Infection Area: Localized (nasal) or disseminated (takes time to develop)
Signs: Nasal – lethargy, bloody nasal discharge, nasal pain, sneezing, ulceration surrounding the nostrils, nosebleed.
Disseminated – affects spine, kidneys and other bones, organs and muscles. Other symptoms may include poor appetite, weight loss, muscle wasting, fever, weakness, lethargy, limping, vomiting, blood in the urine, urinary accidents, and lymph node enlargement. German Shepherds are overrepresented.
Mortality: Nasal infections can be treated fairly successfully; but the prognosis is poor for disseminated infections.
Contagiousness: Not contagious between animals.
Blastomycosis
Geographical Location: Eastern halves of United States and Canada
Cause: Blastomyces dermatitidis spores that live in moist soils with decaying matter.
Infection Route: Commonly inhaled; skin route is secondary
Infection Area: Usually systemic/disseminated
Signs: coughing, fever, lethargy, loss of appetite, exercise intolerance, difficulty breathing, enlarged lymph nodes, and weight loss.
Mortality: 40% – 90%
Contagiousness: Not contagious between mammals
Candidiasis (Thrush)
Geographical Location: None
Cause: Candida albicans (a yeast)
Infection Route: Numerous; burns, inflamed tissue, catheters, high-carbohydrate diets have been implicated.
Infection Area: Generally skin, but also urinary and gastrointestinal tracts can be affected depending on dog’s immune system and if catheters may have been used.
Signs: Skin irritation or open sores
Mortality: Unknown
Contagiousness: Not contagious between animals
Coccidioidomycosis (Valley Fever)
Geographical Location: Mexico, Southwest United States, expected to spread to Canadian border and Western States
Cause: Coccidioides immitis or Coccidioides posadasii
Infection Route: Respiratory
Infection Area: Initial signs in animals and humans are coughing, fever, weight loss, lack of appetite, and lack of energy. Disseminated Valley Fever can affect one or many parts of the body including the central nervous system and bones. Signs of disseminated Valley Fever are lameness or swelling of limbs, skin lesions, back or neck pain, with or without weakness/paralysis, seizures and other manifestations of brain swelling, soft abscess-like swelling under the skin, swollen lymph nodes, non-healing skin wounds that ooze fluid.
Mortality: 90% of treated dogs survive; but untreated dogs have serious and debilitating illness
Contagiousness: Not contagious between animals.
Dermatophytosis (Ringworm)
Geographical Location: Worldwide; thrives on damp surfaces; can live on furniture, hairbrushes, clothing, combs, towels, bedding, etc.
Cause: Several species of Dermatophytes
Infection Route: Skin
Infection Area: Localized to skin
Signs: Rough, circular lesions that can become inflamed and scab over.
Contagiousness: Contagious between animals and humans
Histoplasmosis
Geographical Location: Eastern halves of United States and Canada
Cause: Histoplasma capsulatum spores that live in moist soils that are generally contaminated with bird or bat feces
Infection Route: Inhalation or Consumption
Infection Area: Inhalation route can be localized, but can disseminate. Consumption route can also be localized to gastrointestinal tract or disseminate. Prolonged exposure increases risk of disease development.
Signs: Localized respiratory – labored breathing or cough. Gastrointestinal – persistent diarrhea, straining, tarry or bloody stools. Disseminated – enlargements of lymph nodes and some organs, skin lesions, joint pain or lameness, and eye infections. Other non-specific signs can be weight loss and fever.
Contagiousness: Not contagious between animals
Malassezia dermatitis (Yeast infection)
Geographical Location: None
Cause: Malassezia pachydermatis
Infection Route: Bodily reaction to underlying food sensitivity and/or seasonal/environmental allergen.
Infection area: Localized to skin
Signs: Itching, redness, musty “dog” odor, thickened skin, external ear infections, and crusty and flaky skin.
Contagiousness: Not contagious between animals
Conclusion
As you read over this snapshot of fungal infections in dogs, you probably realized that many of the signs and symptoms could indicate several different viral, bacterial or fungal infections.
A couple of items that help veterinarians prioritize fungal infection diagnoses are geographical locations and lifestyles. For instance, let’s say you took your companion dog to a dog park along a river in Wisconsin and a few days later he developed fever, coughing, or inappetence. Could it be distemper, kennel cough or blastomycosis? You don’t know. So, a descriptive context such as “dog park by a river in Wisconsin” is better than simply “dog park” when you take your companion dog to the veterinarian.