Current Vet

In this episode of Current Vet, Dr. Lottie talks about scabies, the mites that cause the condition, how we should approach diagnosis and what to warn owners about when it comes to zoonotic infections 

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Timeline:
00:00 Intro
00:48 Case
03:00 Aetiology & Pathogenesis
07:10 Clinical Signs
08:44 Diagnosis
11:33 Treatment
16:47 Zoonosis
19:27 Prevention
20:19 Key Points
22:06 Outro

References

Current Vet is an educational podcast intended for veterinary students, veterinary professionals, and individuals with an interest in veterinary medicine.

All content provided in this podcast and its associated materials is for educational and informational purposes only. It is not intended as, and must not be considered a substitute for, professional veterinary advice, diagnosis, or treatment.

Any clinical cases discussed in this podcast are fictional, and are designed to reflect typical or likely clinical scenarios for educational purposes. They do not represent specific real-life cases, clients, or animals.

While every effort is made to ensure accuracy and alignment with current evidence at the time of publication, veterinary medicine is a rapidly evolving field, and recommendations may change over time.

Creators and Guests

Host
Dr. Lottie Wilkinson
Creator and host of the Current Vet podcast

What is Current Vet?

The podcast that makes veterinary medicine simple.

In each episode, Dr. Lottie breaks down clinical conditions, cases, and concepts across species, focusing on pathophysiology, decision-making, diagnostics, and what actually matters in practice. It’s the kind of context that makes your knowledge finally click.

Every month, we’ll also have honest conversations with guests about the incredible variety of veterinary medicine, what you can do with a vet degree and how to think bigger about your career.

Whether you’re cramming for exams or looking for a soundtrack for your dog walk, Current Vet will make vet med simple

Intro

Hello, hello and welcome back to Current Vet, the podcast that makes veterinary medicine simple. I'm your host, Dr. Lottie, and today we're talking about scabies, also known as sarcoptic mange. We're gonna mainly focus on dogs because canine sarcoptic mange is the form you're most likely to see in practice, but we will also touch on cats, some wildlife, a bit of livestock, and people where it's relevant.

By the end of this episode, you should feel really confident recognizing scabies, understanding why these dogs are so itchy, knowing how to approach diagnosis when you can't find the mite, and knowing how to treat the patient properly thinking about all those , in contact animals and the zoonotic risks as well.
So let's start with our case.

Case

A two-year-old male neutered Cocker Spaniel called Milo is presented to your clinic for severe itching. His owner says that he's been scratching for about three weeks now, but over the last few days it has become much, much worse. He's waking them up at night, chewing his legs, rubbing his face along the carpet, and generally seems really uncomfortable.

He has never had skin disease before, and the owner is worried because this has come on quite suddenly. Milo is generally well in himself. He's still eating, drinking, and behaving normally apart from this itching. His vaccines are up to date, but his parasite prevention has been inconsistent.

He lives with another dog and the owner also mentions that they recently started walking in a nice natural wooded area On exam, Milo is bright and alert, but he is extremely pruritic. You can barely examine him without him to scratch or chew. His ear margins are crusted. There are papules and crusts around his elbows.

There's erythema and alopecia around the hocks, and his ventral abdomen is red and excoriated from self-trauma. You gently rub the edge of one ear and Milo immediately starts to scratch with his hind leg. That response is actually called the pinnal-pedal reflex, and it's classically associated with sarcoptic mange.
Because it is not diagnostic on its own, a positive reflex does not automatically mean the dog has scabies and a negative reflex doesn't fully rule it out. But in a dog like Milo with that severe pruritus, ear margin crusting, the elbow and hock lesions, it is a really useful clue.

So at this point, your differential list should include allergic skin disease, something like atopic dermatitis, flea allergy dermatitis, or food-responsive dermatitis. You should also think about superficial pyoderma, Malassezia dermatitis, Cheyletiella mites, demodecosis, possibly dermatophytosis, also known as ringworm, and a lesser differential is maybe something like contact dermatitis. But of course, scabies is gonna be really high on that list

Aetiology / Pathogenesis

So what is scabies? Scabies is a contagious parasitic skin disease caused by mites from the genus Sarcoptes. In dogs, the mite we're usually talking about here is Sarcoptes scabiei variant canis. So these mites are very small. They're round, kind of oval-shaped mites that live in the superficial layers of the skin.
They are not like fleas, which move around on the skin surface and jump between animals. They are not like ticks, which attach and feed in one place, and they are not like demodex, which live down in the hair follicles and the sebaceous glands. Sarcoptes mites are burrowing mites. So the adult female mite burrows into the stratum corneum, which is that outer layer of the epidermis.

She then lays eggs within these burrows. Those eggs hatch into larvae, and the larvae then develop through nymph stages into adult mites. The whole life cycle usually takes around two to three weeks and happens on the host

Transmission usually happens through direct contact with an affected animal. In dogs, that typically means another dog, but foxes are also possible sources of infection as well. So in Milo's case, those new walks around the wooded area is a possible risk for exposure.

Scabies can also spread in environments where animals are housed closely together, so places like shelters, kennels, , rescue centers, breeding facilities, and then also multi-dog households. The mite isn't gonna survive indefinitely when it's off the host because it relies on the host for that life cycle, but it can survive long enough in the environment for contaminated bedding and equipment or shared resting areas to matter for indirect transmission,

So when you take a history, it's worth asking about contact with other dogs, any history of being rescued or kennels, grooming facilities, daycare, possible wildlife exposure, or any other itchy animals in the household, or even if any people in the household are itchy as well So how is this mite's life cycle gonna cause the itching that we see in infected animals?

So the first part is gonna be direct physical irritation of the skin. The mites are burrowing through the epidermis, and that burrowing is gonna damage the skin barrier. And then the female mites lay eggs in the burrows, and as the mites feed and move and reproduce, the skin is exposed to mite antigens, mite faeces, and secretions

But the severe itch that we see with scabies is not just because of that physical irritation
A really big part of it is due to hypersensitivity. So the dog's immune system or the affected animal's immune system reacts to those mite antigens, and this immune response drives a lot of the inflammation and pruritus, which is why dogs with scabies can be unbelievably itchy even when the mite burden is actually really quite low This is gonna be really important when we're talking about diagnosis because you can do lots of skin scrapings and really not find many mites at all or actually find none, but the dog may still have severe disease because the clinical signs are being driven by that exaggerated inflammatory hypersensitivity response.

So as the skin becomes inflamed, you start to see erythema, which is that redness. We see papules, crusting, scaling, and alopecia. The dog then scratches, chews, rubs, and bites at the skin because it is so itchy, which then causes self-trauma. That self-trauma further damages the skin barrier and it makes secondary bacterial or yeast infections much more likely.

So by the time you are seeing a dog, you may not just be dealing with the mites, you may be dealing with the mites, the inflammation, the excoriation, the barrier damage, the secondary pyoderma, and potentially things like malassezia as well

Clinical Signs

So what clinical signs are we gonna see in a patient with scabies? The main sign is, of course, intense pruritus. These dogs are often really, really, really itchy. They can scratch constantly. They can chew at themselves. They may rub their face or body on furniture. They may wake their owners up overnight from this incessant scratching.

Some dogs become really restless or irritable because they're just so uncomfortable. Other typical lesions are gonna include those papules, that erythema, crust, scale, alopecia, and excoriations from scratching. In more chronic cases, we can also see things like lichenification, hyperpigmentation, and thickened skin.
The classic kind of distribution of these lesions is the ear margins, elbows, hocks, ventral chest, ventral abdomen, and sometimes the face. The ear margins are particularly useful if you see a severely itchy dog with crusty ear margins, scabies should be on your differential list for sure

And this is when we're going to use that pinnal-pedal reflex we spoke about before to support your suspicion. So this is basically when you rub the margin of the ear and it triggers a scratching motion from the hind limb of the animal. It is a helpful clue because many dogs with sarcoptic mange will have a positive response, but remember that it is not perfect

Diagnosis

Okay, so let's talk a little bit about diagnosis. The classic diagnostic test is a superficial skin scrape. So because Sarcoptes mites live in that superficial epidermal layer, you do a superficial scrape rather than deep scrapings. So good sites to sample are gonna be those hotspots that we mentioned, those common locations that we find mites, so the ear margins, elbows, hocks, and any crusted papules or lesions that you see on the body.

Ideally, you kind of wanna choose areas that are affected but not completely destroyed by self-trauma because the dog may have scratched away most of that epidermal layer that the mites would be burrowed in. On microscopy, you're then looking for adult mites or eggs or, or faeces or other evidence of infestation.
If you find them, brilliant, you've got your diagnosis. But very often you actually don't find them, and is the main diagnostic problem with scabies. Skin scrapes can confirm the disease, but negative scrapes do not rule it out. So a couple of reasons for this. Firstly, the mite burden can be very low.

You may have sampled an area that doesn't actually contain any mites. The dog may have removed the mites through grooming or scratching, and as we said earlier, the clinical signs are typically driven more by that hypersensitivity than huge numbers of mites, so it's actually quite difficult to get a good sample of them

Other tests can sometimes help as well, so fecal flotations Can actually occasionally identify mites or eggs that may have been swallowed during grooming, although it's not gonna be your, your kind of go-to diagnostic test in everyday practice, a lot of cases are gonna be diagnosed based on the overall picture, so the history, the clinical signs, that lesion distribution, and then a positive response to treatment and exclusion of other differentials.

So this is where something like a therapeutic trial can come in. So if scabies is high on your differential list, it is reasonable to treat for scabies even if you haven't found a mite.

So this is gonna include a good acaricide treatment, treating all susceptible or in-contact animals, managing any secondary infections , cleaning the environment, and then obviously allowing enough time to see a response But a poor treatment trial can be really misleading.

So if you treat one dog once, ignore potentially another dog in the household or a contaminated environment, and then decide it can't be scabies because the itch has not completely resolved a week later, that's not gonna be a good trial and a good test

Treatment

Let's now talk about how to treat Milo. So the goals of treatment are to kill the mites, treat all in-contact animals, reduce transmission, manage secondary skin disease, relieve discomfort, and of course, prevent recurrence or reinfestation. There are several effective treatment options for sarcoptic mange, and the best choice depends on where you're practicing and what products are actually licensed, of course.

And then we also have things like breed considerations, um, sensitivities, - any concurrent medications, and owner factors, if they are able to be compliant with the formulation and make sure that all treatments are up to date. So common options are gonna include isoxazolines, selamectin, moxidectin, ivermectin, and in some cases, we might also use lime sulfur dips.

So isoxazolines are now commonly used in small animal practice, and they are gonna be our drugs ending in -lena. So afoxolener, florfelena, sarolener, , lotilena. These drugs act on the arthropod ligand-gated chloride channels, and this then leads to parasite paralysis and death. So in practice, they're really convenient because they're given orally, and they have activity against fleas and ticks as well as mites.
Selamectin and moxidectin are going to be your macrocyclic lactones. They act on the parasite chloride channels causing parasite paralysis and death. These are often topical products and can be useful in cases where oral medication is not ideal. Maybe your dog is really difficult to tablet.

And the owner isn't able to stay consistent with that treatment. There is a big caution here, however, and that is gonna be the MDR1 gene mutation risk. So dogs with that mutation, classically those collie breeds, are really susceptible to neurotoxicity from certain drugs, including ivermectin.

So toxicity can cause those neuro signs like ataxia, tremors, blindness, depression, and comatose. So we need to be really careful with those breeds and make sure that we are not prescribing these drugs for them Lime sulfur is another option. It is an , older option. It's quite messy. It's quite smelly.

It needs to be applied every week for around one to two months, and it's not especially popular with owners, but it can still be useful in some situations, particularly if those other options aren't appropriate for whatever reason. So whichever treatment you choose, the most important thing is that we need to be treating all susceptible and contact animals. So in Milo's case, this means that the other dog in the household must be treated too, even if he's not currently itchy

If we're not treating that dog, they may continue to carry mites, become clinical later, and then you can end up with reinfection. So treating in-contact animals gives you a much better chance of actually clearing the problem all in one go

Environmental management is also important. So sarcoptes mites, as we say, don't live forever away from the host, but things like bedding and blankets or grooming equipment can contribute to ongoing exposure for these animals. So owners should make sure that they wash the bedding and blankets, clean any grooming tools really well, give the house a bit of a vacuum, and avoid sharing bedding between animals while they're being treated

You also need to reduce contact with other animals until infected animals are clear. So we need to be really vigilant on avoiding dog parks, daycares, grooming, kennels, any training classes, any close contact with other dogs that could potentially become infected

If Milo has signs of a secondary pyoderma

Mild infections could be managed with a bit of topical therapy, so like chlorhexidine products. But systemic antibiotics may be needed if the infection is quite widespread or deep or severe, or it's not being managed effectively with those topical medications. , And culture and sensitivity can also be considered if infection is recurrent or just non-responsive.

The final part of treatment is going to be itch relief. So these dogs can be extremely, extremely uncomfortable And once acaricides have been started, short-term anti-inflammatories like prednisone can also be considered in some cases to improve welfare and relieve that itch

Owners do need to know that the itch may not stop immediately This is gonna be really important because otherwise they may think that the treatment has failed after a couple of days. But even if the mites are dying, the skin is still inflamed and that hypersensitive reaction is still trying to settle down.
, And the barrier damage also takes time to repair. So pruritus often just improves gradually over a couple of days, a couple of weeks, and then the crusting and alopecia and secondary infections can also take longer to resolve.

Zoonosis

Okay, I do wanna quickly mention scabies is zoonotic. So we do need to talk to owners about the human risk as well Canine sarcoptic mites are adapted to dogs,

But they can cause the itchy lesions in people, particularly in areas that have been in contact with the dog, so like the arms or legs or abdomen. In people , canine scabies typically causes a short-term, like transient dermatitis rather than a full ongoing infestation the same way as a human-adapted scabies mite can, but it can still be very uncomfortable.

So client advice should include making sure to avoid close contact with the infected dog until treatment
has ended. Not letting the dog sleep in the bed during that particularly infectious period. Washing bedding and blankets. Treating those in-contact pets as we said before. And then if they do think they've developed sk- itchy lesions, seeking medical advice

As we said right at the start, this episode was really focused on dogs, but it is useful to understand where scabies fits in with some other species as well. So cats - can occasionally be affected by Sarcoptes, but feline scabies is more commonly associated with Notoedres cati, which is the feline mange mite.
So notoedric mange is very pruritic and contagious. It's gonna cause that crusting and alopecia around the ear margins and the face and neck, and sometimes actually around the paws as well. It can become quite generalized in severe cases

So this is gonna be an important differential for an itchy, crusty cat, particularly in a high-density, like a rescue or multi-cat environment. In livestock, sarcoptic mange can occur in species like pigs and can be really important as both an individual animal welfare issue and a herd problem as well.
So in pigs it causes obviously that pruritus, rubbing, crusting, and also production losses. And then the principles are gonna be really similar, so that contagious mite just causes skin irritation, hypersensitivity. And then control, it requires treating all those in-contact animals and managing the environment to prevent re-infestation.

Humans actually have their own form of scabies caused by the human-adapted mite, Sarcoptes scabiei variant hominis, and that is different from canine scabies. But canine mites can still cause that dermatitis

Prevention

Prevention of scabies is mainly about reducing exposure, using really good parasite control and acting quickly when cases are suspected. So for an individual pet dog, that means maintaining good ectoparasite prevention, avoiding contact with known infected animals, limiting exposure to wildlife when possible, treating cases really promptly, and treating in-contact animals when scabies is suspected or confirmed
In shelter environments or kennels and rescues, affected animals should be isolated and exposed animals need treatment as well. And then we need to implement really tight cleaning protocols and make sure to restrict any movement between groups so we're not getting reinfection or continued spread

Key Points

If you're not gonna remember anything else from today's episode, - make sure you remember these next points. So scabies or sarcoptic mange is a contagious parasitic skin disease caused by Sarcoptes scabiei mites. The mites burrow into the superficial epidermis, but much of the severe pruritus is caused by hypersensitivity to those mite antigens.

Classic signs are gonna include intense pruritus, papules, crusting, bit of alopecia, excoriations, and then potentially a secondary infection. And common affected sites are the ear margins, elbows, hocks, and ventrum. The pennal-pedal reflex is a really useful diagnostic clue, but it is not , 100% specific for scabies.
Skin scrapings can confirm scabies if you find mites or other evidence of infection, but false negatives are common, so a negative scrape does not rule it out. Our treatment options are gonna be isoxazoline, selamectin, moxidectin, ivermectin, or lime sulfur, but be aware to not use ivermectin in breeds at risk of the MDR1 mutation All susceptible in-contact animals must be treated even if they are not showing clinical signs.

And environmental management is also really important, so making sure to clean the bedding, any blankets, any equipment, and any shared areas. Scabies is zoonotic, so owners need clear advice , about human skin lesions and should be told to contact their doctor if they see any signs.

Outro

And that is scabies.

Thank you so much for listening to this episode of Current Vet. If you found it helpful, follow or subscribe wherever you get your podcasts, and share it with a friend or colleague who could use a little dermatology refresher as well. As always, if there is a topic you'd like covered in a future episode, let us know in the comments below or find us on Instagram and TikTok at veterinaryvista.

We'll see you next time