A potential new tool to help with the eradication of cats on islands
Control and eradication of feral cats: field trials of a new toxin
Murphy, E.C.,1,2 Shapiro, L.,3 Hix, S.,3 MacMorran, D.3 & Eason, C.T.3,4
Research & Development Group, Department of Conservation, PO Box 13 049,
Christchurch 8141, New Zealand. E-mail: [email protected]
Invasive Animals Cooperative Research Centre, University of Canberra, Canberra, ACT
Connovation Ltd., 36B Sir William Ave, East Tamaki, Manukau 2013, New Zealand
Faculty of Agriculture and Life Sciences, Lincoln University, PO Box 94, Lincoln,
Feral cats (Felis catus) have caused the decline and extinction of threatened
species on islands worldwide. Their eradication or control is an essential part of restoring
biodiversity on these islands. In most situations, a combination of lethal techniques are
required to remove feral cats, including trapping, hunting and poisoning. Para-
aminopropiophenone (PAPP) is being developed as a new, humane poison for feral cats.
Mammalian carnivore species appear more susceptible to PAPP than birds, so it potentially
has higher target selectivity than other available toxins. A proprietary formulation of PAPP
(PredaSTOP®) developed by Connovation N.Z. Ltd. has been shown to kill cats humanely
when delivered in a meat bait in pen trials. Two field trials of the formulation were
undertaken with radio-collared cats. Toxic baiting was carried out by placing meat baits
containing 80 mg PAPP in bait stations. 5/8 radio-collared cats in the South Island study and
13/16 radio-collared cats in the North Island study were poisoned. In the latter study, an
additional three cats without collars that were monitored using infra-red cameras were also
poisoned. Our results indicate that PAPP is an effective toxin for cats in the field, with
potential application for their eradication or control on islands.
Control; eradication; feral cat; Felis catus; field trial; humane; para-
aminopropiophenone; PAPP; poison; radio-tracking; toxin
Running Head: Field trials of a new cat toxin INTRODUCTION
Domestic cats (Felis catus) were brought to New Zealand from 1769 onwards and
transported to many offshore and outlying islands. As well as causing some initial extinctions,
they are responsible for the ongoing decline of a number of threatened species (Dowding and
Murphy 2001; Gillies and Fitzgerald 2005). Cats have caused the extinction and decline of
threatened species on islands worldwide and their eradication or control on these islands is an
essential part of preserving and restoring biodiversity (Courchamp et al. 2003; Nogales et al.
2004). In most situations several lethal techniques are required to achieve their eradication,
including trapping, hunting and poisoning (Veitch 1985, 2001; Nogales et al. 2004). In a
recent review of cat eradications on islands, the application of toxic baits targeting cats was
used in 32% of operations where the eradication methods were documented (Campbell et al.
Para-aminopropiophenone (PAPP) is being investigated as a new humane toxin for
introduced predators, including feral cats, in both New Zealand and Australia (Marks et al.
2004; Fisher et al. 2005; Murphy et al. 2007; Johnston etal. this issue). Previous research on
PAPP has explored its potential as a cyanide antidote (Baskin and Fricke 1992), as a radio-
protective agent (DeFeo et al. 1972), and as a selective toxin for controlling coyotes, Canis latrans (Savarie et al. 1983). The toxic effects of PAPP appear to be related to the rapid
formation of methaemoglobin in some species. A high concentration of methaemoglobin
leads to a rapid and lethal deficit of oxygen in cardiac muscle and the brain, resulting in
animals becoming lethargic and unconscious prior to death (Vandenbelt et al. 1944; Marrs et al. 1991). PAPP has generally lower oral toxicity to birds than to mammalian carnivores, so
presents some degree of target selectivity (Savarie et al. 1983; Fisher et al. 2008; Eason et al.
2010). PAPP is rapidly metabolised and excreted and is unlikely to cause secondary
poisoning (Wood et al. 1991; Eason et al. 2010). Dogs (Canis familiaris), laboratory rats
(Rattus norvegicus) and macaques monkeys (Macaca fascicularis) given sub-lethal doses of
PAPP excreted 75-85% of it within 24 hours (Wood et al. 1991). Methylene blue is a widely-
available and effective antidote for methaemoglobinemia caused by PAPP poisoning
A proprietary formulation of PAPP (PredaSTOP®) has been developed by Connovation N.Z.
Ltd. Feral cats fed 80 mg of PAPP in this formulation in meat baits became lethargic after 22-
55 minutes, lost consciousness without spasms or convulsions and died after 54 to 125
minutes (Murphy et al. 2007). The aim of the study reported here was to determine the field
efficacy of PredaSTOP® in reducing feral cat numbers, to provide data for registration
MATERIALS AND METHODS Study areas
The first trial was undertaken in May 2008 in the South Island, at two sites in North
Canterbury; the Patoa pig farm near Culverden (c. 480 ha) and the Kate Valley landfill near
Waipara (c. 100 ha). The second trial was undertaken in June 2009 at Ngamatea Station,
between Taihape and Napier on the central plateau in the North Island. This site was c. 1500
ha, and consisted mainly of pasture, pine windbreak hedging, and seral vegetation.
Cats were trapped using Havahart® live capture traps and were injected intramuscularly with
Domitor® (50-100 µg/kg) in the first trial, and Domitor® (50-100 µg/kg) and Ketamine (100
mg/kg) in the second trial. Radio transmitters with an external whip aerial were attached to
the cats using collars. After securing the collars in the first trial, the cats were injected
intramuscularly with Antisedan® (125-375 µg/kg) to reverse the anaesthesia until they were
fully revived (c.10-30 min) and then released. In the second trial, cats were returned to
covered cages to recover and released when fully revived (c.30-40 min). The radio
transmitters (Sirtrack Ltd) emitted 40 pulses per minute with a ‘mortality’ function that
switched to 80 pulses per minute after 12 hours without movement. Tracking was carried out
using a TR4 (Telonics, Inc) receiver and a Yagi three-element aerial. Three infra-red motion-
detection cameras (DigitalEye™ 12.1 in IR Stealth Flash, Pixcontroller) were used in the
second trial to monitor cats visiting bait stations. Cameras were moved around the study area
and put at each station for at least two nights in the pre-feeding stage and were then used to
check that cats came back to the stations after being radio-collared. Once this was confirmed,
the cameras were used to monitor three cats without collars that were consistently identified
PredaSTOP® paste (200 mg) was applied to c.15 g meat baits to deliver 80 mg of PAPP in
each bait. Meat baits consisted of minced beef (trial 1) and minced rabbit (trial 2) in a ball
with the PAPP paste placed inside. ‘Submarine’ bait stations (see Fig 2 in Warburton and
Poutu 2002) were used in both trials to minimise non-target interference. Before toxic baiting,
pre-feeding was carried out by removing the wire mesh from the ends of the bait stations and
placing tracking cards inside. Once prints of cats were found in the majority of feed stations
the wire mesh was then attached to either end of the bait station, limiting access to the top
Twenty-two bait stations were spread around the pig farm and 10 bait stations were
distributed at the landfill. There were three nights of PAPP baiting at the pig farm and eight
nights at the landfill. 1-3 baits were placed in each bait station and checked each day to assess
condition. Cats were radio-tracked daily to determine whether they were still alive and in the
Toxic baiting was carried out for five nights by placing five baits in each of 22 bait stations
spread around the farm. Weather conditions were recorded and baits were checked, counted,
removed each morning and replaced each evening. A snow storm on the fourth night meant
that this night of baiting was delayed until the following night. As before, cats were radio-
Eleven cats were captured and radio collared - six at the Patoa pig farm and five at the Kate
Valley landfill. Of the six collared cats at the pig farm, one left the study area before toxic
baiting, four were found dead after the first night of baiting and the remaining cat survived.
Four cats without collars were also found dead, three after the first night of baiting, and one
Of the five cats collared at the Kate Valley landfill, two were found dead before toxic baiting
and appeared to have been crushed by heavy machinery. Of the remaining three collared cats,
one was found dead after the first night of baiting and the other two survived. One cat
without a collar was found dead after the first night of baiting and a second cat without a
collar was found dead after the second night. The additional nights of baiting at the landfill
site did not increase mortality amongst the radio-collared cats.
All 11 cats found dead after PAPP baiting (5 radio-collared and 6 without collars) showed
cyanosis around the mouth, consistent with poisoning by PAPP. Cats poisoned by PAPP in
this trial ranged in weight from 1.31-3.35 kg.
Twenty-one cats were caught and radio-collared - one of these died and four left the study
area before toxic baiting. Thirteen of the 16 that were alive and in the study area at the time
of toxic baiting died (Table 1). The three cats without collars monitored by cameras were also
found dead after toxic baiting. All 16 cats showed cyanosis around the mouth, consistent with
poisoning by PAPP. The 16/19 cats poisoned results in a mortality rate of 0.84 (95%
binomial confidence interval 0.60-0.97 for underlying mortality rate based on assuming each
cat had an equal probability of mortality). Cats poisoned by PAPP in this trial ranged in
Over the five nights of toxic baiting there was confirmed bait take by feral cats on 23
occasions, with sixteen of these attributed to the radio-collared and camera-monitored cats.
Unidentified cats were therefore also probably poisoned, as bait take and cat prints were
recorded from seven bait stations where no carcasses were found. On four occasions multiple
baits in stations were not entirely eaten but a monitored cat was found dead in the vicinity
The results reported here are from the first field trials of PAPP baits targeting feral cats in
New Zealand. They support the results of earlier cage trials (Murphy et al. 2007), and suggest
that PAPP is an effective new tool for feral cat control in the field. Mortality was also
achieved when cats partly ate baits, indicating that using multiple baits in stations could be an
effective strategy to overcome the reluctance some cats may have about eating whole baits.
Although feral cats are naturally cautious and can be difficult to trap (Twyford et al. 2000;
Veitch 1985, 2001), cameras showed that all 21 cats in the North Island trial fed regularly on
non-toxic bait from the submarine stations before being captured and collared. Four of the
collared cats left the trial area immediately after release, suggesting that these procedures
may have changed their normal ranges and behaviour. Although the other cats remained in
the area, their foraging behaviour may also have been affected by capture and an association
with human presence, possibly explaining why three of them did not enter the bait stations
after being collared. In operational poisoning using bait stations, without prior live-capture, a
higher bait take and resulting mortality seems likely.
Nogales et al (2004) recommended that feral cats should be routinely eradicated from islands
where possible and that new techniques should be developed to do this. PAPP promises to be
a useful addition to available tools for cat eradications, especially on larger islands and in the
early stages of eradication. After trapping and hunting, the most frequently used technique for
eradicating cats from islands is direct poisoning (Nogales et al. 2004). Poisoning can be the
most successful and effective technique for reducing the population quickly (Veitch 1985;
Twyford et al. 2000) and the most commonly used toxin for primary poisoning is sodium
monofluoroacetate (1080, Campbell et al. this issue). Although its use for island eradications
of cats has been successful, the use of 1080 can be controversial; it has broad-spectrum
toxicity to mammals and birds, and primary and secondary mortality of non-target species
can therefore be a concern (Eason 2002; Weaver 2003).
Although PAPP has some selectivity, in that mammalian carnivores are more susceptible
weight-for-weight than most bird species tested, there is considerable inter-specific variation
in response to PAPP in terms of susceptibility and toxico-dynamics (Savarie et al. 1983;
Fisher et al. 2008; Eason et al. 2010). Also, as most birds weigh considerably less than cats,
some bird species could still be at risk of poisoning if they ingest PAPP baits intended for
feral cats (Murphy 1995). Reptiles may also be vulnerable to the toxic effects of PAPP.
Acetaminophen (paracetamol) is used for control of brown tree snakes (Boiga irregularis) on
Guam (Savarie et al. 2001) and this compound, like PAPP, elevates methaemoglobin to lethal
levels in some species. No evidence was found of any non-target species eating PAPP baits in
our trials, and we believe the submarine bait stations we used help ensure targeted delivery in
Other methods of delivering PAPP to feral cats (and other pests) are also being trialled. A
tunnel system has been designed which uses compressed gas to propel a measured amount of
PAPP paste onto the abdomen of pests as they pass over a trigger. Oral exposure occurs when
the animal grooms the paste from its coat. Cage trials have achieved proof of concept for this
method as a means of killing stoats (Mustela erminea), indicating that a device capable of
safely delivering multiple lethal doses of toxin without regular resetting can be produced
In conclusion, the promising mortality established in these trials suggests that PAPP could be
a useful additional tool for the control and eradication of feral cat populations. Despite some
selective toxicity of PAPP for mammalian carnivores, there are potential non-target issues for
birds that access bait, but it may be possible to lessen these by development of targeted
delivery systems, such as bait stations, the tunnel system mentioned above, or by specific bait
presentations that exploit cat feeding behaviour and physiology (Marks et al. 2004; Marks et al. 2006; Johnston et al. this issue). Few toxins are currently available for the control or
eradication of cats. We believe the development of PAPP represents a significant advance. It
is humane in comparison to available toxins, more toxic to cats than birds, and presents a low
Thanks to John Dowding for help and advice with the North Canterbury trial and comments
on this manuscript. Thanks also to the two referees for their helpful comments and Ian
Westbrooke for statistical advice. Thanks to staff at the Kate Valley landfill and the Patoa
pig farm for letting us work at their sites and helping with fieldwork. Thanks to Renata Apatu
of Ngamatea Station for agreeing to the North Island study and to Martin Benstrum at Central
Districts Pest Control for identifying an ideal site. Graham Dixon helped set up the North
Island trial and provided ongoing support. Alan Beer and Rod Dixon at Hawkes Bay
Regional Council supplied live capture traps and field support. Thanks also to Dr Lynn Booth
for QA analyses and Paul Aylett for formulation.
The use of PAPP in these field studies was authorised by the Environmental Risk
Management Authority approval numbers HSC000319 and HSC10000. Provisional
registration was also obtained from the NZ Food Safety Authority (V9513). All animal
manipulations were approved by the Lincoln University Animal Ethics Committee
(Approval# 189). The authors acknowledge the funding support of the NZ Department of
Conservation under DOC Science Investigation No. 3932.
Baskin, S.I. and Fricke, R.F. 1992. The pharmacology of p-aminopropiophenone in the
detoxification of cyanide. Cardiovascular Drug Reviews 10: 358-375.
Bodansky, O. and Gutman, H. 1947. Treatment of methemoglobinema. Journal of Pharmacology and Experimental Therapeutics 90: 46-56.
Campbell, K.J.; Harper, G.; Algar, D.; Hanson, C.C.; Keitt, B.S. and Robinson, S. This issue.
Updated review of feral cat eradications on islands.
Courchamp, F.; Chapuis, J-L. and Pascal, M. 2003. Mammal invaders on islands: impact,
control and control impact. Biological Review 78: 347-383.
DeFeo, F.G.; Fitzgerald, T.J. and Doull, J. 1972. Synthesis and biologic activity of p-
hydroxylaminopropiophenone. Journal of Medicinal Chemistry 15: 1185-1187.
Dowding, J.E. and Murphy, E.C. 2001: The impact of predation by introduced mammals on
endemic shorebirds in New Zealand: a conservation perspective. Biological Conservation99:
Eason, C. 2002. Sodium monofluoroacetate (1080) risk assessment and risk communication.
Eason, C.T.; Murphy, E.C.; Hix, S.; Henderson, R.J. and MacMorran, D. 2010. Susceptibility
of four bird species to para-aminopropiophenone. DOC Research & Development Series 320.
Department of Conservation, Wellington. 15p.
Fisher, P.M.; O’Connor, C.E. and Murphy, E.C. 2005: Acute oral toxicity of p-
aminopropiophenone to stoats. New Zealand Journal of Zoology 32: 163–169.
Fisher, P.; O’Connor, C.E. and Morriss, G. 2008: Oral toxicity of p-aminopropiophenone to
brushtail possums (Trichosurus vulpecula), dama wallabies (Macropus eugenii), and mallards
(Anas platyrhynchos). Journal of Wildlife Diseases 44: 655–663.
Gillies, C. and Fitzgerald, B.M. 2005: Feral cat. In King, C.M. (ed.): The handbook of New Zealand mammals, pp. 308–326 Second edition. Oxford University Press, Oxford, UK.
Johnston, M.; Algar, D.; O’Donoghue, M. and Morris, J. This issue. Field efficacy of the
Curiosity® feral cat bait on three Australian islands.
Marks, C.A.; Gigliotti, F.; Busana, F.; Johnston, M. and Lindeman, M. 2004. Fox control
using a para-aminopropiophenone formulation with the M-44 ejector. Animal Welfare 13:
Marks, C.A.; Johnston, M.J.; Fisher, P.F.; Pontin, K.M. and Shaw, M.J. 2006. Differential
particle size ingestion: promoting target-specific baiting of feral cats. Journal of Wildlife
Marrs, T.C., Inns, R.H., Bright, J.E. and Wood, S.G. 1991. The Formation of
Methaemoglobin by 4-aminopropiophenone (PAPP) and 4-(N-hydroxy) aminopropiophenone.
Human and Experimental Toxicology 10: 183–188.
Murphy, E.C.; Lavrent, A.; MacMorran, D.; Robbins, L. and Ross, P. 2005. Development of
a humane toxin for the control of introduced mammalian predators in New Zealand.
Proceedings of the 13th Australasian Vertebrate Pest Conference, pp.137-142. Wellington,
Murphy, E.C.; Eason, C.T.; Hix, S. and MacMorran, D.B. 2007. Developing a new toxin for
potential control of feral cats, stoats and wild dogs in New Zealand. In Witmer, G.W., Pitt,
W.C. and Fagerstone, K.A. (eds.). Managing vertebrate invasive species, pp. 469–473.
Proceedings of an International Symposium, National Wildlife Research Centre, Fort Collins,
Nogales, M.; Martin, A.; Tershy, B.R.; Donlan, C.J.; Veitch, C.R.; Puerta, N. Wood, B. and
Alonso, J. 2004. A review of feral cat eradications on islands. Conservation Biology 18: 310-
Savarie, P.J., Huo Ping Pan, D., Hayes, J.D., Roberts, G.J., Dasch, R. Felton and E. W.
Schafer. 1983 Comparative acute oral toxicity of para-aminopropiophenone. Bulletin of Environmental Contamination and Toxicology 30: 122-126.
Savarie, P.J.; Shivik, J.A.; White, G.C.; Hurley, J.C. and Clark, L. 2001. Use of
Acetaminophen for large-scale control of brown tree snakes. Journal of Wildlife Management
Twyford, K.L.; Humphrey, P.G.; Nunn, R.P. and Willoughby, L. 2000. Eradication of feral
cats (Felis catus) from Gabo Island, south-east Victoria. Ecological Management &
Vanderbelt, J.M.; Pfeiffer, C.; Kaiser, M.and Sibert, M. 1944. Methemoglobinemia after
administration of p-aminoacetophenone and p-aminopropiophenone. The Journal of Pharmacology and Experimental Therapeutics 80: 31-38.
Veitch, C. R. 1985. Methods of eradicating feral cats from the offshore islands in New
Zealand. In Moors, P. J. (ed.). Conservation of island birds: case studies for the management of threatened island birds, pp.125-142. Cambridge, International Council for
Veitch, C. R. 2001. The eradication of feral cats (Felis catus) from Little Barrier Island, New
Zealand. New Zealand Journal of Zoology 28: 1-12.
Warburton, B. and Poutu, N. 2002: Effectiveness of three trapping systems for killing feral
cats DOC Science Internal Series, No. 50. Department of Conservation, Wellington.
Weaver, S. 2003. Policy implications of 1080 toxicology in New Zealand. Journal of Rural and Remote Environmental Health 2: 46-59.
Wood, S.G.; Fitzpatrick, K.; Bright, J.E.; Inns, R.H. and Marrs, T.C. 1991. Studies of the
pharmacokinetics and metabolism of 4-aminopropiophenone (PAPP) in rats, dogs and
Cynomolgus monkeys. Human and Experimental Toxicology 10: 365–374.
Table 1. Details on the feral cats monitored at Ngamatea Station during the poison trial, and
their fates. Toxic baiting was carried out for five nights, using five baits in each of the 22 bait
GRANO PAIN RELIEF & WELLNESS CENTER p:(973) 383-5533 f:(973) 383-5501 p:(973) 827-0003 f:(973) 827-0063 [email protected][email protected] NUTRITION EVALUATION: 04/17/2012 PATIENT INFORMATION DATA USED FOR ANALYSIS Height: 5'6"Weight: 145Blood Pressure: 139 / 95O2 Level: 83%Heart Rate: 98 PRIMARY FINDINGS SUGGESTIVE OF The purpose for this nutrition and lif
Adverse Drug Reaction Alert Bulletin (ADRAB) A fortnightly alert to remind you of common and not so common adverse drug reactions Please inform [email protected] of any adverse drug reaction that you think we need to remind people of – a brief vignette is good – or just email the adverse reaction . Confidentiality applies Proton pump inhibitors – remember GI adverse effects a