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Austwickia chelonae

Austwickia chelonae is a very contagious turtle disease that is still poorly understood. Placed in the Dermatophilaceae family of gram-positive bacteria, A. chelonae was named after the late botanist, Peter K. C. Austwick.

Despite having a name that is frankly hard to pronounce, these bacteria cause some very distinct symptoms that are easy to spot. In this article, we’re going to gain an understanding of what A. chelonae is and what these symptoms are. We’ll also discuss when to see a vet and how to prevent your pets from catching this disease in the first place.

What is Austwickia chelonae?

Austwickia Chelonae in reptiles
Here is a sampling of Austwickia Chelonae in reptiles. We have not been able to get images yet of tortoises with the disease, but these provide concrete examples – source

As I mentioned earlier, A. chelonae is a gram-positive bacterium in the Dermatophilaceae family. This is important to know, because it means that certain antibiotics will be more effective against it than others.

As with other members of the Dermatophilaceae family, it causes a disease known as Dermatophilosis. This is a type of skin infection that affects many animal species around the world and is characterised by the formation of growths known as Granulomas. In Turtles, we call it Chelonid Dermatophilosis.

As far as we know, Dermatophilosis from A. chelonae affects lizards, snakes, turtles, and tortoises. In one case, it was even identified in a King Cobra.

In captive reptiles, it now seems to be spreading amongst some of the more popular species. Of particular concern to us Chelonian (turtle and tortoise) enthusiasts is that it is spreading amongst captive Sulcata Tortoises (Geochelone sulcata).

This doesn’t mean other turtle species are safe from it, however. A. chelonae has also been identified in Australian side-neck turtles, Angulate tortoises (Chersina angulata), and Egyptian Tortoises (Testudo kleinmanni). In my opinion, we should assume that any turtle or tortoise could be infected if it encounters this disease.

Symptoms

Dermatophilosis from A. chelonae can be distinguished from other bacterial infections by the distinctive wart-like growths or boils it causes. These are known as granulomas. This symptom occurs because when infecting a reptile, A. chelonae irritates deep layers of skin tissue and provokes an inflammatory growth reaction (sometimes called a hypersensitivity reaction).

The granulomas can be just a bump at first, but usually grow into larger, yellowish boils. At this point, they may form scabs as well. In many cases with infected turtles, the granulomas have formed boils on the legs and jaw, and scabs on the nose. In larger turtles and tortoises, these lesions can be up to 1cm wide.

In previously healthy animals, the granulomas may stay on the surface. In weak animals, or animals left untreated, they will enter deeper tissue layers and eventually the body cavity. At this point, A. chelonae may also cause Mouth Rot (Necrotizing Stomatitis).

When the disease gets very serious, joint inflammation and Septicemia may also be present.

Let’s do a quick re-cap of the main A. chelonae symptoms:

  • Dry bumps, boils, or scabs on skin of legs and jaw – these may be yellow
  • Scabs on face
  • Mouth rot
  • Trouble walking from joint inflammation
  • Septicemia

When to see a vet

Any time you see unexplained scabs or what look like boils on your pets’ skin – it’s time to see a vet. It’s important to remember that the symptoms of A. chelonae are incredibly like some other chelonian diseases – all of which need veterinary treatment.

The boils, for example, can look like abscesses, the difference being that abscesses don’t tend to multiply. Either, way, you will need a vet to resolve the issue.

At this point, there is no home treatment for this disease, and it is recommended that you try your best to find a specialist reptile vet – even if it means travelling some distance. A. chelonae is still a poorly known disease, so don’t hesitate to ask your vet if they’ve heard of it. If they haven’t, they will nonetheless be able to access information that will help with treatment.

Treatment

With diseases such as A. chelonae, diagnosis can usually be done by taking a skin biopsy. After taking the biopsy, your vet will either examine it under a microscope to look for signs of Dermatophilosis or send it to a laboratory for a bacterial culture.

If a bacterial culture is taken, this may not give 100% certainty of whether A. chelonae is present. It will however make gram testing possible, and this will help your vet make the call. When a bacterial culture is used for diagnosis, vets occasionally start treating before the results come back if they have a good idea of what is causing the illness. This is nothing to worry about – sometimes it’s best to try to get a head start!

Following diagnosis, your vet will probably debride the boils. This means surgically removing the infected tissue under anaesthesia. If you’ve caught the infection early, debridement will only be minor surgery. And though this sounds serious, it will help recovery and healing in the long run. After debridement, the wounds will be treated with topical antibiotics such as povidone-iodine or silver sulfadiazine.

As with any severe bacterial disease, the most essential part of treatment will be a course of oral or intravenous antibiotics – known as systemic antibiotics. To our knowledge, veterinarians have yet to decide on one set antibiotic for treating this infection. What we do know, however, is that cephalothin, minocycline and ampicillin have proved effective.

Which of these your vet chooses, or whether they choose a related antibiotic, will be down to their opinion and what they have experience with. During treatment, your pet may have to stay at the vets for a period of several weeks.

After treatment, you should monitor your pet over the coming months to make sure the disease doesn’t come back. If any signs of a recurrence appear, go straight back to the vets.

Prevention

To prevent A. chelonae infections there are three main things we need to keep in mind:

  1. It is highly contagious and thought to spread through contact with skin.
  2. Weakened skin, through injury, parasitic infection or incorrect humidity levels is more likely to catch it.
  3. Just one new pet can spread it to the rest.

Let’s break these points down, so that we can understand how they relate to preventing the disease.

First, when we say that a disease is spread through contact with the skin, it doesn’t just mean contact between animals. It means contact between an animal’s skin and any infected surface. The infected surface could be the substrate, the hide box, the water bowl, or even food left in too long.

Always remember that strong hygiene measures are a must when dealing with reptiles. One of the main reasons for this being that germs thrive in warm, humid conditions. As we all know, warmth and reptiles go hand in hand! Your best way to combat this factor is to regularly clean and disinfect your animal’s enclosure with a veterinary approved disinfectant.

Or, if your animal lives outside, regularly clean its enclosure furniture and rotate it to a different patch of the lawn every week or so.

When it comes to weakened skin, good overall husbandry is the best way of preventing it. For preventing injury, safety should be your primary goal when designing any turtle or tortoise home. Turtles and tortoises are wonderful, inquisitive animals, but let’s be honest… they can be very clumsy.

Sharp rocks, high ledges, and shallow water (for aquatic turtles) can all lead to bumps, cuts or scrapes that allow infections like A. chelonae to take hold.

Always look at lots of examples of professionally designed enclosures before setting up your own. Then during set up, keep asking yourself: could an accident happen in this space?

Another point to consider carefully is the level of humidity your pet is exposed to. In a lot of articles, we put an emphasis on getting heat and humidity right, and for good reason. Diseases like A. chelonae love humidity. In fact, when Dermatophilosis, the condition caused by this family of bacteria occurs in horses, people often call it “rain rot”. In animals like the Sulcata Tortoise (Geochelone sulcata) which naturally needs low humidity, weakened skin and bacterial infections can be directly caused by a humidity level that is too high. To prevent this scenario, always thoroughly research the heat and humidity requirements for your pet species and make them a priority.

External parasites are uncommon in aquatic turtles, asides from leeches which are surprisingly pretty much harmless. In tortoises and terrestrial turtles, parasites can occur but are typically easy to spot. Inspect your pet from head to toe every week or so to make it is parasite free and seek veterinary assistance if you spot any.

Finally, let’s talk about quarantine as a prevention method. You may often have read that quarantining new pets away from the others is necessary – and this is 100% correct. Not only do you need to quarantine them, but you also need to make sure you aren’t taking any shortcuts.

No water bowl, feeding utensil, decoration, or anything else can pass between your new pet’s enclosure/area and the others. After handling the new animal, always wash your hands and wrists with antibacterial soap and change your shirt before attending to the rest of your pets.

Quarantine any new animal for 4 to 6 weeks, in a separate room, or in a separate area of the yard. This will allow any disease time to become apparent. During this time, there can be no exceptions at all – it really is that serious! As I mention earlier, it only takes one infected animal to create a problem.

Wrapping up

Austwickia chelonae causes a serious skin disease known as Dermatophilosis. This condition may rest on the surface of the skin or attack deeper tissue layers if the animal is unhealthy or has been living in poor husbandry conditions.

Whilst home treatment is not recommended, several antibiotics have been proven to be effective against this bacterium. If you suspect it in one of your pets, seek immediate veterinary help and you may be able to stop it in its tracks.

When dealing with such a serious condition, it’s obvious that prevention is a safer bet than treatment. It’s also easier and less expensive! Whenever you introduce a new pet to your home, be sure to quarantine and monitor it for at least a month.

As always, comment or get in touch for more advice!

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