bioRxiv preprint doi: https://doi.org/10.1101/2021.01.22.427753; this version posted January 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 1 Risk and protective factors of feline tooth resorption in 8115 Finnish cats 1,2 ¶ 1¶ 1,2,3* 1 2 Katariina Vapalahti , Henriikka Neittaanmäki , Hannes Lohi , Anna-Maija Virtala 3 4 1Department of Veterinary Biosciences, University of Helsinki 5 2Department of Medical and Clinical Genetics, University of Helsinki 6 3Folkhälsan Research Center 7 8 *Corresponding author 9 Email: [email protected] 10 ¶ These authors contributed equally to this work. 1 bioRxiv preprint doi: https://doi.org/10.1101/2021.01.22.427753; this version posted January 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 11 Abstract 12 Tooth resorption (TR) is the most common dental disease in cats. It causes painful lesions in the teeth, 13 the only treatment being tooth extraction. The prevalence of the TR is high in clinical studies while 14 the estimate in the population sample is unknown. The aetiology of the disease remains unclear, but 15 associations to old age, breed, other oral and dental diseases, viral infections and certain 16 environmental factors have been suspected. We wanted to determine the prevalence, risk factors and 17 heredity of feline TR in a population sample of Finnish cats. We collected health and environmental 18 information of 8115 Finnish cats in 41 breeds through an online survey targeted for breeders and 19 owners. The prevalence of veterinary-diagnosed TR was 3.9% in the whole data and 15% in cats 20 diagnosed with oral or dental disease. Results indicated an increased risk by age and decreased risk 21 by constantly available food. Periodontitis and stomatitis were more common in the TR-affected cats. 22 The interaction between gingivitis, dental calculus, and age suggests that the predisposition of young 23 cats to TR is associated with gingivitis, which could partially be prevented by proper dental hygiene. 24 The observed differences between breeds highlight the genetic contribution. 25 26 Introduction 27 Tooth resorption (TR) is the most common dental disease in cats [1]. It is a painful disease 28 characterised by progressive dental destruction, which eventually results in loss of teeth. Dental 29 radiography is necessary to evaluate the overall situation [1]. Prevention of the disease is not possible 30 since the aetiology is still unknown. The goal of treatment is to relieve the pain and discomfort caused 31 by these lesions [2]. The main cause of destruction are odontoclasts, which are multinuclear cells that 32 resorb mineralized tissue [3]. Odontoclasts are responsible for resorption of deciduous teeth in young 33 animals, but their abnormal activity in permanent teeth is the cause of TR [4]. The reason for this 34 process remains unclear, although many different theories have been proposed. Tooth resorption can 2 bioRxiv preprint doi: https://doi.org/10.1101/2021.01.22.427753; this version posted January 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 35 include plaque accumulation, inflammation of the adjacent tissue and alveolar bone ankylosis [5]. 36 Because the pathogenesis of tooth resorption has been unclear, many different terms have been used 37 to describe the lesion, i.e. erosion, neck lesion, FORL (feline odontoclastic resorptive lesion). 38 Nowadays, most used term is TR. 39 40 TR is a relatively new disease, which has become more common in the last decades [6]. Almost no 41 resorptions could be found in feline skulls from the 1930–1950’s but starting from 1960’s they were 42 increasing in number [7]. First publication about TR came out in 1955 [6]. The size and origin of the 43 study population have had a major impact on the reported prevalence of TR in previous studies 44 varying from 29-85% (Table 1). Most studies are based on a small clinical sample (n< 150) and no 45 reports have been published yet in a large population sample. TR exists also in large cats, such as 46 leopards and lions, but rarely in humans and dogs [1]. The increasing number of tooth resorption 47 indicates a change in the environment of domestic cats [4]. For example, the factors preventing 48 resorption in the outer surface of the teeth could have been compromised [1]. Only lesions that occur 49 in the crown or in the cemento-enamel junction can be detected clinically [1]. However, resorption 50 can occur at any surface of the teeth or in the root and can lead to massive destruction in the adjacent 51 tissue. 52 53 Table 1. Prevalence of feline tooth resorption in previous studies. NK = not known Reference Country Target population Study population Method Prevalence (n), average age (%) (years) Coles 1990 Australia General 64, NK Clinical 52 [13] anaesthesia van Wessum Netherlands Dental procedure 432, NK Clinical 62 et al. 1992 [7] 3 bioRxiv preprint doi: https://doi.org/10.1101/2021.01.22.427753; this version posted January 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. van Wessum United Dental procedure 78, NK Clinical and 67 et al. 1992 States radiographs [7] Lund et al. United General 145, 7.9 Clinical 48 1998 [15] States anaesthesia Ingham et al. United Clinically healthy 228, 4.9 Clinical and 29 2001 [16] Kingdom test animals radiographs Pettersson & Sweden Sedation 96, 6.0 Clinical and 32 Mannerfelt radiographs 2003 [17] DeLaurier et United Clinically and 13, NK Electron 85 al. 2009 [5] States radiographically microscopy normal teeth Our study Finland Finnish cat 8115, 5.3 Questionnaire 3.9 / 15 population: all / cats with oral or dental disease 54 55 American Veterinary Dental College has developed a classification for tooth resorption based on their 56 radiographic appearance. In type 1 tooth resorption there is a focal radiolucent area in the tooth that 57 appears otherwise normal with a normal periodontal ligament space. In type 2 tooth resorption, there 58 is decreased radiopacity, which indicates that the root is being replaced with alveolar bone. In type 3 59 tooth resorption, there are signs of both type 1 and type 2 resorptions [8,9]. The same cat can suffer 60 from different types of resorptions [9]. The three resorption types have been suspected to have 61 different aetiologies [10]. 62 63 Unlike the previous clinical studies, our aim was to investigate the prevalence of veterinary-diagnosed 64 TR, its risk factors and variation between breeds in a large population sample of Finnish cats collected 65 during 2012–2015 using an online feline health survey data [11]. 4 bioRxiv preprint doi: https://doi.org/10.1101/2021.01.22.427753; this version posted January 22, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 66 67 Results 68 69 Prevalence 70 Our cat population consisted of 8115 cats in 41 breeds, of which 4290 (53%) were females. 2070 71 (26%) cats were diagnosed with oral or dental disease and 316 cats had veterinarian diagnosed TR. 72 The mean age of the cat population was 5.3 years - for cats without TR 5.1 and for cats with 73 veterinarian diagnosed TR 9.8 years. The prevalence of veterinary-diagnosed TR in our study was 74 3.9% (95% CI 3.5–4.3%, Table 1). The prevalence increased strongly by age, being 0.4% in 1 to <3 75 years old, 3.0% in 3 to <7 years old, 8.8% in 7 to <11 years old, and 11.6% in at least 11 years old 76 cats. TR was not reported in cats under one year of age. For comparison, in subgroup of cats that had 77 been diagnosed with oral or dental disease, the prevalence of TR was 15.2% (95% CI 13.5–16.8%, 78 Table 1), increasing again by age 3.7%, 12.6%, 24.3% and 28.1%, respectively. 79 80 We did not find any significant difference between the TR prevalence in purebred cats and non- 81 pedigree house cats (3.8%; CI 3.4–4.3% and 4.2% and CI 3.3–5.3%, respectively, P = 0.551, Fisher). 82 However, in some breeds, the prevalence was much higher or lower than in the entire population or 83 in-house cats – high in Siamese (9.9%), Abyssinian (9.3%), Oriental Shorthair (9.1%) and Cornish 84 Rex (8.9%), and much lower than average in Turkish Van (0.4%) and Birmans (1.3%). TR was not 85 reported in breeds of Burmilla, American Shorthair, Don Sphynx, Egyptian Mau, Kurilian Bobtail, 86 Manx, Neva Masquerade and Seychellois. However, these breeds were present in low numbers in our 87 dataset.