Hey, pet parents. The word "mange" can sound pretty scary, and it brings to mind images of stray dogs with patchy hair loss. Mange is simply a skin disease caused by microscopic mites. There are two main types of mange in dogs, and they are completely different diseases with different causes, signs, and treatments. Let's clear up the confusion about Demodectic Mange and Sarcoptic Mange.
Demodectic Mange (Demodex)
What is it?
Demodectic mange is caused by the Demodex canis mite. Here's the surprising part: these mites are a normal inhabitant of your dog's skin! In fact, all dogs (and all people) have a small number of Demodex mites living in their hair follicles. They are passed from the mother to her puppies in the first few days of life.
In a healthy dog with a normal immune system, these mites cause no problems at all. Demodectic mange as a disease occurs when the dog's immune system is not able to keep the mite population in check. The mites proliferate out of control, leading to hair loss and skin inflammation.
Demodectic mange is not contagious to other dogs or to people.
Who gets it?
There are two main forms:
- •Localized Demodectic Mange: This is common in puppies under 18 months of age. Their immune system is still developing, and they can't always keep the mites under control. It usually appears as one or more small, well-defined patches of hair loss, most often on the face.
- 1Generalized Demodectic Mange: This is a more serious condition. It can occur in juvenile dogs with a genetic defect in their immune system, or in adult dogs whose immune system is suppressed by another underlying disease (like Cushing's disease, hypothyroidism, or cancer). In this form, there are large areas of hair loss all over the body.
Signs:
- •Patches of hair loss (alopecia).
- •The skin is usually not itchy in the early stages.
- •In generalized demodicosis, the skin can become very red, crusty, and infected with bacteria, which can then become itchy.
Diagnosis and Treatment:
The diagnosis is made by performing a deep skin scrape. Your vet will scrape the skin with a blade to collect a sample from the hair follicles and will look for the cigar-shaped Demodex mites under a microscope.
- •Localized Mange: In puppies, over 90% of localized cases will resolve on their own without any treatment as the immune system matures.
- •Generalized Mange: This form requires treatment. The new class of isoxazoline flea and tick preventatives (the oral products like Bravecto, Nexgard, Simparica, and Credelio) have been a complete game-changer for treating Demodex. They are incredibly safe and effective. A few months of treatment is usually curative. It's also important to look for and treat any underlying disease in adult-onset cases.
Sarcoptic Mange (Scabies)
What is it?
Sarcoptic mange, also known as Canine Scabies, is caused by the Sarcoptes scabiei mite. Unlike Demodex, these mites are not normal inhabitants of the skin. They are highly contagious parasites that are passed from an infected dog (or a fox) to another dog.
These mites burrow into the skin to lay their eggs, which causes an intense allergic reaction and severe itching.
Sarcoptic mange is highly contagious to other dogs and can also be temporarily contagious to people, causing a red, itchy rash.
Signs:
- •INTENSE Itchiness: This is the hallmark sign. The dog is relentlessly itchy and can't stop scratching.
- •Crusty Ear Tips: The edges of the ears often become crusty and scaly.
- •Hair Loss: Especially on the ears, elbows, hocks, and belly.
- •Self-Trauma: The intense scratching can lead to sores and secondary skin infections.
Diagnosis and Treatment:
Diagnosing scabies can be tricky. Your vet will perform a skin scrape, but the mites can be very difficult to find. Often, a diagnosis is made based on the intense itchiness and a positive "pinnal-pedal reflex" (when the vet scratches the edge of the ear, the dog's back leg will start to "thump").
Because the mites are so hard to find, if a vet suspects scabies, they will often just treat for it. This is called a "treatment trial."
Just like with Demodex, the isoxazoline flea and tick preventatives are the treatment of choice for scabies. They are extremely effective at killing the mites. All other dogs in the household should also be treated.
With effective treatment, the prognosis for a full recovery from both types of mange is excellent.
Sources & Further Reading:
- •VCA Animal Hospitals - Mange in Dogs
- 1Merck Veterinary Manual - Mange in Dogs