The basic steps involved in the treatment of tick paralysis are:
1. Thorough searches of the colony daily and prompt response to calls from the community for rescues.
2. Quick assessment to decide the prognosis. Signs that indicate the bat has little chance of survival and should be euthanased include:
- pulmonary edema
- a rectal temperature below 34 degrees centigrade
- lack of righting reflex
- severe infestation by maggots
- a low irregular heart rate
- inability to swallow
- presence of gasping
- inattention to what you are doing
If unsure of the prognosis, wait to treat the bat back at the hospital so there’s more time to assess. The adrenaline rush of seeing a human at close quarters can often make the bat seem in better condition than it really is.
If the bat is treatable, find and remove the tick immediately. There are many different ideas about how to do this. Some people like to poison or freeze the tick in situ. However this is very difficult in a wild animal with long hair and sharp teeth near the site of the tick. Others like to use various forms of forceps but again there are difficulties. We currently remove the tick very quickly and competently by having finger nails of the right length!
It is not is the best interests of the bat to try to treat it when the prognosis is poor.
3. Keep the bat calm. If the bat is female and has young, we need to make a decision of whether to leave the pup on the mother until we return to the bat hospital. The pup may be more settled, but we take the risk of a pup being bitten on the feet by the distressed mother. If we remove the pup, we tie coloured wool around the ankle of mother and baby for later identification. If the pup is removed from its’ mother, we wrap it in a cloth with a dummy in its’ mouth. We deal with any live maggots on the pup especially if in eyes.
5. Administer tick anti-toxin, about 2.5mls per adult bat mixed with 3-10mls of Hartmann’s fluids depending not he level of dehydration. We warm the mixture, more so if the bat is cold. We then inject the mix into the peritoneum with a 21 guage needle.
6. Provide the bat with a comfortable lying down position and the opportunity to grasp on to something with its thumbs. Our cages have mesh on the top and sides to allow this. Offer small amounts (1ml) of diluted mango and apple juice, more if the swallow is normal
7. Monitor the heart rate of the bat. Normally it is a strong 360 beats per minute, but this can drop to be very slow and irregular, or occasionally become extremely rapid. It can be difficult to distinguish between the rapid heart and the normal heart. Do not allow bat to try to hang until the heart rate is at least 300 beats per minute. Monitor closely but remember it is a wild animal and will be stressed by too much contact.
It may be necessary to administer other drugs under the direction of a veterinarian. We do not have a resident veterinarian but are supervised by the local Tableland Veterinary Service. We have been involved in research with Prof Rick Atwell from the University of Queensland’s Department of Veterinary Sciences. He is probably Australia’s leading veterinary authority on tick paralysis. His visit in November 2001 led to improvements in our approach to the treatment of bats with tick paralysis as well as the publication of a paper in the Australian Veterinary Journal in June 2003. Go to www.ava.com.au
Two tick Do not allow bat to try to hang until the heart rate is at least 300 beats per minute. Monitor closely but remember it is a wild animal and will be stressed by too much contact. It may be necessary to administer other drugs under the direction of a veterinarian.
This bat is being assessed for tick paralysis – rectal temperature and ability to swallow. For this, we prefer to use a large towel rather than gloves for protection.
Drawings of the various stages of the life cycle of the paralysis tick, Ixodes holocyclus. Tick paralysis is usually caused by a single adult female tick, but every second year or so we get a bat outside of the usual tick season with tick paralysis caused by the nymph stage of the tick. They are always infested with large numbers of nymphs.
In a bad season we find up to 50 tick-paralysed bats a day. These bats, although found dead or euthanased are usually in good condition for researchers. These bats have contributed to a number of important research papers, notably by Drs Sam Fox and David Westcott.