CHAPTER SIX
Parasites that cause skin problems
Chapter Contents
Mange: Scabies and Demodex mites
Ticks
Fleas
Lice
Skin sores – bacterial skin infections
In this chapter you can find information about different parasites that cause skin problems in dogs and cats.
At the end of the chapter, there is also some information about how skin problems in animals can be a problem for human health.
Dogs can have two different types of mange mites. The mites are called:
- Scabies mite – scientific name: Sarcoptes scabiei
- Demodex mite – scientific name: Demodex canis
Scabies mange
Scabies mange is caused by scabies mites.
It is sometime also called ‘sarcoptic mange’.
The scientific name for dog scabies mite is Sarcoptes scabiei var canis.
How do scabies mites cause sickness in dogs?
It only takes a few scabies mites to make a dog very, very itchy.
Scabies mites chew a burrow in the dog’s skin and lay their eggs. The mites’ spit makes the dog itch.
Dogs catch scabies mites from other dogs with scabies, or from places where mangy dogs have been. Old foam mattresses and dirty bedding are good hiding places for scabies mites.
Scabies mite seen under a microscope. Image courtesy Graeme Brown
Did you know?
Scabies mites can only live for about 3 days in the environment. After 3 days, they will die of starvation if they’re not on a host animal to feed.
On dogs, scabies mites can breed up and spread quickly from dog to dog.
If there is dog scabies in a house, most dogs from that house will have scabies mange.
Chapter 7 has information about treating dogs for scabies mange.
Does dog scabies cause health problems for people?
Yes. Dog scabies can cause problems for people.
People have their own type of scabies mite (Sarcoptes scabiei var. hominis). Human scabies can be a major problem for people in communities.
But dog scabies mite (Sarcoptes scabiei var canis) can also cause problems for people.
Dog scabies mites can move from dogs to people. This makes people itchy, but usually only for a few days.
Scabies mites make people and dogs itch so much that they can get sores on their skin. There is more information about skin sores at the end of this chapter.
If people have a weak immune system and catch dog scabies mites, the mites can breed up and cause a type of crusted scabies.
Dogs can also act as a “reservoir” or a hiding place for human scabies mites.
It’s also important to remember that mangy dogs also cause fear and shame for people who live with them. This can impact people’s mental health.
For both the dog and its human family, it is important that dogs are treated for mange and kept healthy.
Demodex mange
Demodex is another type of mite which can cause mange.
Mange caused by demodex mites is sometimes also called ‘demodectic mange’.
The scientific name for dog demodex mite is Demodex canis.
How do demodex mites cause sickness in dogs?
Dogs with lots of demodex mites can lose their hair, but it is different to scabies mange because dogs with demodex are usually not very itchy.
Demodex mites live in the hair roots. The mites die quickly if they are not on a dog.
It is normal for healthy dog to have small numbers of demodex mites.
On some dogs, the demodex mites breed up too much and cause demodectic mange.
Demodex is mostly only a problem for dogs with weak immune systems. Healthy adult dogs do not get demodex from other dogs.
Most dogs that do have a problem with demodex will have gotten the demodex mites from their mother when they were very young, and their immune system was still weak.
Some dog breeds, like Shar-peis, Pitbulls, Bull Arabs and Staffordshire Bull Terriers, have bad genes which can cause problems with demodex mites.
Dogs with bad demodex will usually pass it onto their puppies. It is best to desex dogs with bad demodex, so that they don’t breed.
Chapter 7 has information about treating dogs for demodex mange.
Does dog demodex cause health problems for people?
No. People do not catch demodex from dogs.
Demodex mites live in the dog’s hair roots.
Puppies can get demodex mites from their mother when they drink milk.
How to tell what is causing a dog’s mange
Mangy dogs can all look the same. A dog with scabies mange can look the same as a dog with demodex mange.
A vet can do a skin scrape and look at the mites under a microscope to tell if a dog has scabies mange or demodex mange.
Without a microscope, there a few things to look for, that can help you tell the difference between scabies and demodex mange.
A mangy dog probably has scabies mange if:
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- It is very, very itchy.
- It has crusty skin.
- Other dogs in the house have mange too.
- People in the household are itchy too.
- You know there is a problem with dog scabies in the community.
- Ivermectin or Moxidectin work very quickly to fix it.
See Chapter 7 to learn more about treating mange.
A dog probably has demodex mange if:
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- It looks mangy but is not very itchy.
- It had a mother or father with the same problem.
- It is a pig-dog type breed, or a Shar-Pei, Pitbull or Staffordshire Bull Terrier.
- Ivermectin or Moxidectin do not work very well.
See Chapter 7 to learn more about treating mange.
AMRRIC has made a poster which summarises the differences between scabies and demodex mange. Click here to download the poster.
Some other skin problems can look like mange. These include:
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- Ringworm
- Flea allergy – see the section on fleas, later in this chapter
- Scarred skin from bad ticks, old mange or hot water burns
If a mangy dog isn’t getting better with treatment, talk to your vet or AMRRIC about what else might be the cause of the problem.
Scabies mange or demodex mange?
Dogs with probable demodex mange. Image courtesy Stephen Cutter.
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Dog with probable demodectic mange. Image courtesy Courtney Falls/AMRRIC.
Dog with probable scabies. Image courtesy Ted Donelan.
Old dog with probable demodex mange.
This old dog probably has demodex. He is not very itchy. He has lost his hair but has no open sores or scabs. Old animals have weaker immune systems. When animals have a weak immune system, the demodex mites can breed up and cause hair loss. (Image courtesy Stephen Cutter.)
TICKS
Ticks are small parasites that bite, attach to the skin and feed on the blood of animals (or sometimes humans).
When they feed on blood, ticks’ bellies swell up like a balloon.
Ticks are more common in warm, humid weather, and can be a big problem, especially in the wet season in the Top End.
Ticks survive well in the environment. They like to live in long grass or bushy areas, but some ticks can breed up quickly in house yards too.
One female tick can lay up to 5000 eggs, so without long-lasting medicine, it can be hard to get rid of ticks.
There are lots of different types of ticks, but there are only two types of ticks that usually cause problems for pets in communities:
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- Brown dog tick – scientific name: Rhipicephalus sanguineus
- Paralysis tick – scientific name: Ixodes holocyclus
Brown dog tick
Brown dog ticks are the type of ticks that are seen most in communities.
They are the tick that people see all over dog’s ears and backs. Brown dog ticks can also be on other areas of the dog, like on their armpits, groin and belly.
Brown dog ticks are not usually a problem for cats.
Brown dog ticks are only found where there are dogs. They are not bush ticks.
If dogs are not given tick medicine the ticks build up in the environment.
Chapter 7 has information about tick medicines that will stop brown dog ticks.
How do brown dog ticks cause sickness in dogs?
Like all ticks, brown dog ticks bite through the skin and feed on blood.
Brown dog ticks can be a big problem for dogs, in a number of ways:
Brown dog ticks come in lots of sizes. The smaller ticks in this dog’s ear are young; the big grey ticks are adult females. Image courtesy of Jan Allen/AMRRIC.
1. Animal Welfare
If a dog has too many ticks it is an animal welfare problem.
Ticks make dogs feel itchy and sick. They can make large sores on the dog.
The owner may not want the dog around with so many ticks. This can mean the dog will not get the food and love it needs.
This number of ticks is a health and welfare problem. Image courtesy Jan Allen/AMRRIC
2. Weak Blood: Anaemia
Each tick on a dog sucks blood.
If there are too many ticks the dog will not have enough blood left and will get very weak.
When this happens, we say that these dogs have ‘anaemia’ or are ‘anaemic’.
Dogs and puppies can die from ticks causing anaemia.
This dog has very white gums because it has lost a lot of blood. It is anaemic. Image courtesy Bonny Cumming/AMRRIC.
Vector-borne diseases
Vector-borne diseases are diseases passed from ticks, fleas, mosquitoes or other biting insects, to animals (or people).
There are a number of vector-borne diseases that can be passed from brown dog ticks to dogs, including:
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- Babesiosis
- Anaplasmosis
- Ehrlichiosis
- Haemoplasmosis
- Hepatozoonosis
- Rickettsiosis
Brown dog ticks can carry more than one of these diseases at the same time.
Dog with these diseases can be lethargic (lazy and sleepy), lose weight, have a fever and become anaemic.
Some dogs will recover, but some will die from these diseases.
These diseases are usually worse for young dogs.
Some of these diseases are also a problem for people – see Chapter 8 for more information on vector-borne diseases.
Do brown dog ticks cause health problems for people?
Yes. Brown dog ticks can be a problem for people.
When they breed up, there can hundreds of ticks in a house.
As well as crawling onto dogs, ticks can crawl up the walls, over bedding and onto people.
When there are lots of brown dog ticks in a house, it can make people feel unhappy and stop people sleeping well.
When they are looking for a feed, brown dog ticks sometimes also bite people.
These bites can get infected and turn into a skin sore. There is more information about skin sores at the end of this chapter.
When they bite people, brown dog ticks might also spread vector-borne diseases to people. See Chapter 8 for more information on vector-borne diseases.
There are hundreds of ticks crawling up this cat cage. Image courtesy Jan Allen/AMRRIC.
Did you know?
In other countries, we know that brown dog ticks spread vector-borne diseases that make lots of people sick. We also know that in Australia, other types of ticks can carry tick-borne diseases that make people sick.
We don’t know about any cases of vector-borne disease from brown dog ticks in people in Australia yet, but there is a lot more research needed before we can say for sure.