Veterinary World, EISSN: 2231-0916 RESEARCH ARTICLE Available at www.veterinaryworld.org/Vol.13/January-2020/2.pdf Open Access A descriptive study of ciguatera fish poisoning in Cook Islands dogs and cats: Demographic, temporal, and spatial distribution of cases Michelle J. Gray Master of Veterinary Medicine Program, School of Veterinary Science, Massey University, Palmerston North, New Zealand. Corresponding author: Michelle J. Gray, e-mail: [email protected] Received: 17-09-2019, Accepted: 25-11-2019, Published online: 03-01-2020 doi: www.doi.org/10.14202/vetworld.2020.10-20 How to cite this article: Gray MJ (2020) A descriptive study of ciguatera fish poisoning in Cook Islands dogs and cats: Demographic, temporal, and spatial distribution of cases, Veterinary World, 13(1): 10-20. Abstract Background and Aim: Ciguatera fish poisoning (CFP) is the most common form of seafood toxicosis reported in humans worldwide. Dogs and cats are also susceptible to CFP, but there is little published and much unknown about the condition in these species. This study aimed to document the demographics of canine and feline cases of CFP, to examine the temporal and spatial distribution of cases, and to compare the incidence of animal and human CFP in the Cook Islands. Materials and Methods: Six years of medical records from the Esther Honey Foundation Animal Clinic (the only veterinary clinic in the Cook Islands during the study period) were reviewed to identify cases of CFP. The study variables included the date of presentation, species, age, sex, neutering status, and village/locality. Results: A total of 246 cases of CFP were identified, comprising 165 dogs and 81 cats. The sexes were equally represented; however, within each sex, entire animals outnumbered those that had been desexed. Cases occurred year-round, with slightly higher numbers recorded in spring. Annual case numbers trended downward over the study period. Cases were documented in all regions of Rarotonga and also one outer island (Aitutaki). Fewer cases were seen in areas with a narrow (<200 m) fringing lagoon, compared with a wide (>400 m) lagoon. Conclusion: This study documented epidemiologic patterns of canine and feline CFP cases for the first time. Based on the results, further investigation is warranted to establish whether desexing has a protective effect against CFP. Keywords: cats, ciguatera, Cook Islands, demographics, dogs, epidemiology. Introduction CFP occurs in a corresponding circumglobal belt o o Ciguatera fish poisoning (CFP) is a multisystem between latitudes 35 N and 35 S [29]. It can be assumed toxicosis that afflicts a number of species, including that canine and feline CFP occurs throughout the same humans, dogs, and cats. Cases of canine and feline CFP geographic region, however, to date, all of the published have been described sporadically in literature [1-6]. The case reports [1-6], experimental studies [14-19], and toxicosis has also been discussed in articles and books general articles [7-13] have originated in the Pacific. [7-13]. There were some early experimental studies Within the endemic region, spatial and temporal conducted [14-19], but there have been no objective patterns of Gambierdiscus spp. and ciguatoxin contain- studies of the condition published since the 1980s. ing fish are difficult to predict. Because reef fish tend CFP is caused by the ingestion of fish containing to stay within a defined home range, toxic food webs ciguatoxins. Fish are not inherently toxic but rather can exist in discrete areas. One reef can be affected acquire toxicity through the food chain in coral reef while an adjacent site is “safe” [30,31]. This heteroge- ecosystems [20-22]. Bottom-dwelling dinoflagellates neous, site-specific distribution is further complicated of the genus Gambierdiscus are the source of the CFP by temporal fluctuations in Gambierdiscus abun- toxin [23,24]. Herbivorous fish become toxic after dance and toxicity [32]. Areas previously “safe” may ingesting Gambierdiscus spp. [25,26]. Similarly, car- become ciguateric, and vice versa, as environmental nivorous fish become toxic after eating ciguatoxin factors impact on Gambierdiscus populations [31,33]. containing herbivores [27]. Risk factors for CFP have been studied in peo- CFP is a global phenomenon. Toxic Gambierdiscus ple, but not in animals. On a population level, envi- spp. are found in warm waters of the Pacific, Indian and ronmental processes including reef disturbances and Atlantic Oceans, and the Caribbean Sea [28]. Human climate cycles are thought to influence the spatial and temporal occurrence of CFP [34-36]. On an indi- Copyright: Gray. Open Access. This article is distributed under vidual level, demographic characteristics such as low the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which socioeconomic status, male gender, and age have been permits unrestricted use, distribution, and reproduction in any (inconsistently) associated with CFP in people [37-40]. medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons Finally, there are vector related factors: The risk of tox- license, and indicate if changes were made. The Creative Commons icity is thought to be higher with certain types/species Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this of fish, with certain parts of the fish (e.g., the viscera/ article, unless otherwise stated. and head), and with larger portion sizes [40,41]. Veterinary World, EISSN: 2231-0916 10 Available at www.veterinaryworld.org/Vol.13/January-2020/2.pdf This report is the first to examine the epidemio- Study design logic patterns of CFP in dogs and cats. There are no This was a retrospective case series. data currently available regarding the demographic Case selection characteristics of animals afflicted by CFP. The occur- The paper medical records of the Esther Honey rence of CFP in dogs and cats has never been tracked Foundation Animal Clinic were searched for eligible over time. Spatial analysis of canine and feline CFP cases. At the time of the study, handwritten records cases has never been attempted. Research into these from 2011 onward were available for review. Cases topics is necessary to identify the risk factors for the presenting in the 6-year period March 2011-February toxicity and develop mitigation strategies. 2017 were considered for inclusion. Inclusion criteria This study aimed to document the demographics were: (1) A presumptive diagnosis of CFP documented of canine and feline cases of CFP and to examine the by the attending clinician; and (2) no other diagnosis temporal and spatial distribution of cases. A secondary established during the period of care. objective was to compare the incidence of canine and feline CFP with the incidence of human CFP in the Data collection Cook Islands. Eligible patient files were scanned to portable doc- ument format and assigned a case identification number. Materials and Methods Each patient file was searched to identify the variables of Ethical approval interest: Date of presentation, species, age, sex, neuter- This retrospective review of case records was ing status, and village/locality. Data were collected using deemed to not require ethics approval (Massey Epi-Info software (version 7.2.1.0, CDC, Atlanta, USA). University). The age variable was assigned categorical values Study site based on the following criteria: The study was conducted in the Cook Islands, • Juvenile: Age given as ≤12 months or animal a country in which CFP is endemic in the human referred to as a puppy or kitten population [42]. Several articles evidence that CFP • Adult: Age given as >12 months and <8 years or occurs in Cook Islands dogs and cats as well as their animal referred to as an adult owners [3,4,7,9]. Cases for this study originated from • Senior: Age given as ≥8 years or animal referred the Esther Honey Foundation Animal Clinic, which to as senior, aged, or geriatric provided the only veterinary service in the Cook • Unspecified: Insufficient detail in medical record Islands from 1995 to 2017. to classify the case as juvenile, adult, or senior. Table-1: Study locations: Assignation of geographic sector, lagoon width, and wind exposure. Village/locality Lagoon width1 Wind exposure2 Map reference (Figure-1) Unspecified Not applicable Not applicable - Aitutaki Not applicable Not applicable - Aroa Wide Windward 1 Arorangi Intermediate Leeward 2 Atupa Narrow Leeward 3 Avana Wide Windward 4 Avarua Narrow Leeward 5 Avatiu Narrow Leeward 6 Betela Intermediate Leeward 7 Blackrock Intermediate Leeward 8 Kavera Intermediate Windward 9 Matavera Narrow Windward 10 Muri Wide Windward 11 Ngatangiia Wide Windward 12 Nikao Wide Leeward 13 Ruaau Narrow Leeward 14 Ruatonga Narrow Leeward 15 Rutaki Wide Windward 16 Takuvaine Narrow Leeward 17 Tikioki Wide Windward 18 Titikaveka Wide Windward 19 Tupapa Narrow Windward 20 Turangi Narrow Windward 21 Turoa Wide Windward 22 Tutakimoa Narrow Leeward 23 Vaimaanga Wide Windward 24 1Lagoon width measured in Google earth, classifications based on those of Rongo and van Woesik [35]: Lagoon width <200 m=Narrow; 200 m<lagoon width <400 m=Intermediate; lagoon width >400 m=Wide. 2Wind exposure based on the dominant south easterly wind direction [43] and consistent with that used by Rongo and van Woesik [35]. Veterinary World, EISSN: 2231-0916 11 Available at www.veterinaryworld.org/Vol.13/January-2020/2.pdf Table-2: Excluded cases: Final diagnoses. Species Excluding diagnosis Cat Aborting Cat Abscess Cat Chronic renal failure Cat Delayed organophosphate poisoning Cat Hemorrhagic gastroenteritis and shock Cat Hypoglycemia Cat Vestibular disease Dog Arthritis/hip pain Dog Arthritis/hip pain Dog Gastroenteritis Dog Intestinal parasitism Dog Respiratory disease Dog Respiratory disease/diaphragmatic hernia Dog Spinal injury/disc prolapse Dog Spinal injury/disc prolapse Figure-1: Rarotongan locations: Lagoon width and wind exposure.