Treating Chytrid

Winter 2021 and 2022:  there was a very serious die-off of frog around the nation during these two winters and chytrid fungus was involved but not the only problem these animals had.  Cases that were drawn to our attention also had a bacterial problem that killed them quickly.  The problem was the worst in southern Qld and northern NSW where frogs don't normally brumate (hibernate) during the winter.

While a full treatment protocol to cure chytrid is best, many people are contacting us to say that all their backyard frogs are dying. This is a preventative action we are suggesting for everyone in any cold area, especially if you don't have a rescue group nearby who is experienced with frogs.

Chytrid is a cool climate fungus so tropical locations would only have to worry about this during the winter months. However, many other temperate and upper latitude locations would be dealing with the possibility of chytrid for most of the year.

We are providing this information to assist those who are unable to transport their frogs to us for treatment. However, you should not assume chytrid fungus is actually involved (and start treating for it) unless we have been able to discuss the symptoms with you.   There are many other fungal problems which might be treated differently as well as many other pathogens that make frogs sick but are not publicised in the media.

We don't receive a lot of chytrid cases because we are in the tropics where it doesn't grow well but every case we have seen always has another problem such as a bacterial infection. If you are treating a frog that has chytrid, be prepared to look for other symptoms as the chytrid starts to get killed off.

What YOU can do about chytrid

In the past, the use of heat to kill chytrid has been a standard with some other concurrent approaches (calcium, frog ringers, etc.) but heat can't be used for small frogs, tadpoles, or metamorphs and, even with adults, you can easily kill an adult frog if the temperature is not controlled exactly.  Last winter, we decided to try something completely different which seemed to work just fine and quickly with little chance of killing the frog.  The treatment can even be adapted for use on metamorphs.

The two items you need are some betadine (10% povidone iodine) and rosemary leaves (yes, the rosemary on your spice shelf you use for cooking).  Herbal medicine is a powerful tool that is often shunned by those with a financial interest in drugs but it was around a long time before 'big pharma' showed up.

For medium and large sized frogs, make a cup of rosemary tea (one level teaspoon of rosemary leaves in a cup of hot water - leave to steep until cold; then strain and use the tea as the water bowl in the frog's hospital tank
For small frogs, use 1/3rd strength in their water bowl in the hospital tank
For metamorphs, use the same 1/3rd strength and put in a spray bottle; spray the metamorphs and the vegetation in their enclosure twice a day for five days
Replace the tea in the water bowl with a new cup of rosemary tea every other day for medium and larger frogs - sooner if the tea becomes soiled
Use betadine straight from the bottle to wipe out the hospital tank once a day
every other day, make up the highly diluted solution of betadine solution and distilled/filtered water and give the frog a 60 second bath (avoid the face) in the betadine before returning to the newly cleaned hospital tank (procedures are in the rehab page)

You can also supplement the frog's care with liquid calcium supplement, frog ringers if you can get it, and keep the room a bit warm (27 deg C up to 30C)  but the rosemary is doing most of the work.  Rosemary is a very powerful anti-fungal but it doesn't work on every fungus.

Continue the rosemary and betadine treatments for at least five days or until the frog appears to be well again. Be sure to look out for other symptoms as the chytrid clears because every frog we've ever received that had chytrid also had a bacterial problem.  If you clear the chytrid and the frog is still not eating or pale spots appear on the skin, then take the frog to a vet to have the bacterial problem identified by impression smear so that the bacteria can be narrowed down to a gram positive or gram negative bug.  Don't bother with cultures - they take too long and cost too much.  Our own experience reveals that enrofloxacin is fine for gram negative bacteria and doxycycline is better for gram positive problems.  There may be other useful drugs but it depends on your region and what your vet has available.  We don't seem to have as many choices up here in FNQ.

Prevention for keepers

Preventing chytrid from infecting your pets is far better than trying to recover them. Keep in mind that chytrid is a winter problem so you should include some special procedures in your pet care routine at that time.

Give all your frogs a highly diluted betadine bath once every five days as a preventative (a betadine bath is 1 part "10% povidone iodine" per 250 parts water in a small bowl; sit the frog in the bath for ONLY 30 seconds but avoid the face)
Use new disposable gloves for each frog you handle
Avoid going out to look for frogs in the field during this time unless you are using disinfection procedures for yourself and your gear
Avoid obtaining or disposing of any pet frogs during winter but, if you must, give those frogs a few highly diluted betadine baths during the week before transfer
If you are receiving frogs, keep them separate from your other frogs for at least one month and handle with disposable gloves; give them several diluted betadine baths over that month and do not incorporate to your collection if they are not eating well or show any other abnormal signs such as sluggishness, variations in colour, etc.
If you are in an area that uses tank water, boil that water in the winter months and let cool before using for your frog collection; same applies to water from creeks although it really should be boiled year round

Prevention for pond owners

Exchanging anything with other pond owners is a great way to spread many problems, not just chytrid. Avoid exchanging plants, snails, fish and tadpoles with other pond owners.
When you buy plants from an aquatic nursery, apparently you can try giving them a special bath in the aquarium product "Rapid White-spot Remedy" (we have not tried this ourselves) before introducing them to your pond. Use the directions on the bottle and dilute by half to mix up the bath in a large bowl and let the plants soak in it for several minutes and then rinse off with fresh water before adding to your pond. Check to see if any tadpoles are present before you leave the shop as nursery troughs often attract frogs and then the tadpoles get distributed with the plants. If there notice tadpoles after you get home, you can return them to the nursery or you can raise them in a separate container (our raising tadpoles page will help you). If the nursery is further than 20 km from you, the metamorphs should be returned to the nursery area for release.
Another way to ensure that chytrid can't possibly get into your pond and kill amphibians is to drain the pond entirely each winter and only keep it filled during the warmer months. OR if the pond is small, you can add an aquarium heater to keep the water at 27 deg C for the winter (be mindful of electricity safety when running the cable to the power point). Bird baths and other small containers can be provided for backyard wildlife during the dry months and these can easily be kept regularly cleaned and disease-free. You might also keep a 5L container on your veranda/patio which is filled with rosemary tea or the aquarium heater mentioned above. Any frogs in your yard could be placed in this container for a soak each time you see them (use gloves to handle). This option MIGHT just help them keep chytrid fungus levels down so they don't become overwhelmed and die. There are no guarantees but some kind of help is better than nothing in this case.

Terminal Chytrid

As chytrid progresses to the point of being irreversible, the attack on the nervous system becomes more obvious. In the Common Green (White's/Litoria caerulea), the head can tilt forward to the point that it becomes at a right angle to the back; the toes can curl and the limbs can become paralysed even though the frog is still alive. Both heart rate and breathing slow right down and eventually just stop. The frog's posture becomes withdrawn in temperment and it sits in such as way as to reduce the amount of contact between its skin and the surface it is sitting on. The entire ventral surface can turn a flaming red/orange colour which is quite different to the reddening caused by the bacterial disease "Red leg".

If you have found a frog in this condition, you probably won't be able to save it but a frog disease researcher might want the body as part of their research into this hideous disease. If you don't know how to find a frog researcher in your area, email us and we can assist you.

Handling chytrid for pond owners

It really depends on how much you care about your backyard frogs as to whether you want to intervene if and when chytrid arrives in your yard. What you do about disinfecting your pond can be very involved if your pond is quite large. If your pond is small, prevent a tragedy from occuring in the first place by draining it for the winter (see option 3 on the right side above). If you believe that you might have a chytrid problem and want advice on managing your particular pond, you can contact us to describe your setup and location. In view of the severity of the outbreak over the past couple winters, you might also consider the rosemary tea (on a larger scale) described at the top of this page.

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