So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

Sex Differences in Lifespan

Purebred dog health is thought to be compromised by an increasing occurence of inherited diseases but inadequate prevalence data on common disorders have hampered efforts to prioritise health reforms. Analysis of primary veterinary practice clinical data has been proposed for reliable estimation of disorder prevalence in dogs. Electronic patient record (EPR) data were collected on 148,741 dogs attending 93 clinics across central and south-eastern England. Analysis in detail of a random sample of EPRs relating to 3,884 dogs from 89 clinics identified the most frequently recorded disorders as otitis externa (prevalence 10.2%, 95% CI: 9.1–11.3), periodontal disease (9.3%, 95% CI: 8.3–10.3) and anal sac impaction (7.1%, 95% CI: 6.1–8.1). Using syndromic classification, the most prevalent body location affected was the head-and-neck (32.8%, 95% CI: 30.7–34.9), the most prevalent organ system affected was the integument (36.3%, 95% CI: 33.9–38.6) and the most prevalent pathophysiologic process diagnosed was inflammation (32.1%, 95% CI: 29.8–34.3). Among the twenty most-frequently recorded disorders, purebred dogs had a significantly higher prevalence compared with crossbreds for three: otitis externa (P = 0.001), obesity (P = 0.006) and skin mass lesion (P = 0.033), and popular breeds differed significantly from each other in their prevalence for five: periodontal disease (P = 0.002), overgrown nails (P = 0.004), degenerative joint disease (P = 0.005), obesity (P = 0.001) and lipoma (P = 0.003). These results fill a crucial data gap in disorder prevalence information and assist with disorder prioritisation. The results suggest that, for maximal impact, breeding reforms should target commonly-diagnosed complex disorders that are amenable to genetic improvement and should place special focus on at-risk breeds. Future studies evaluating disorder severity and duration will augment the usefulness of the disorder prevalence information reported herein.

/pdf/prevalence-of-disorders-recorded-in-dogs-attending-primary-d03yclmtgx.pdf

Prevalence of Disorders Recorded in Dogs Attending Primary-Care Veterinary Practices in England

Improved understanding of longevity represents a significant welfare opportunity for the domestic dog, given its unparalleled morphological diversity. Epidemiological research using electronic patient records (EPRs) collected from primary veterinary practices overcomes many inherent limitations of referral clinic, owner questionnaire and pet insurance data. Clinical health data from 102,609 owned dogs attending first opinion veterinary practices ( n  = 86) in central and southeast England were analysed, focusing on 5095 confirmed deaths. Of deceased dogs with information available, 3961 (77.9%) were purebred, 2386 (47.0%) were female, 2528 (49.8%) were neutered and 1105 (21.7%) were insured. The overall median longevity was 12.0 years (IQR 8.9–14.2). The longest-lived breeds were the Miniature poodle, Bearded collie, Border collie and Miniature dachshund, while the shortest-lived were the Dogue de Bordeaux and Great Dane. The most frequently attributed causes of death were neoplastic, musculoskeletal and neurological disorders. The results of multivariable modelling indicated that longevity in crossbred dogs exceeded purebred dogs by 1.2 years (95% confidence interval 0.9–1.4; P

/pdf/longevity-and-mortality-of-owned-dogs-in-england-150bfi8xfa.pdf

Longevity and mortality of owned dogs in England.

Cancer is a common problem in dogs and although all breeds of dog and crossbred dogs may be affected, it is notable that some breeds of pedigree dogs appear to be at increased risk of certain types of cancer suggesting underlying genetic predisposition to cancer susceptibility. Although the aetiology of most cancers is likely to be multifactorial, the limited genetic diversity seen in purebred dogs facilitates genetic linkage or association studies on relatively small populations as compared to humans, and by using newly developed resources, genome-wide association studies in dog breeds are proving to be a powerful tool for unravelling complex disorders. This paper will review the literature on canine breed susceptibility to histiocytic sarcoma, osteosarcoma, haemangiosarcoma, mast cell tumours, lymphoma, melanoma, and mammary tumours including the recent advances in knowledge through molecular genetic, cytogenetic, and genome wide association studies.

/pdf/breed-predispositions-to-cancer-in-pedigree-dogs-2eke8mxfn5.pdf

Breed-Predispositions to Cancer in Pedigree Dogs

Canine perinatal mortality: A cohort study of 224 breeds

Litter Size at Birth in Purebred Dogs--A Retrospective Study of 224 Breeds

The main objective of this study was to estimate the incidence and mortality rates of epilepsy in a large population of insured dogs and to evaluate the importance of a variety of risk factors. Survival time after a diagnosis of epilepsy was also investigated. The Swedish animal insurance database used in this study has previously been helpful in canine epidemiological investigations. More than 2,000,000 dog-years at-risk (DYAR) were available in the insurance database. In total, 5013 dogs had at least one veterinary care claim for epilepsy, and 2327 dogs were euthanased or died because of epilepsy. Based on veterinary care claims the incidence rate of epilepsy (including both idiopathic and symptomatic cases) was estimated to be 18 per 10,000 DYAR. Dogs were followed up until they were 10 (for life insurance claims) or 12 years of age (veterinary care claims). Among the 35 most common breeds in Sweden, the Boxer was at the highest risk of epilepsy with 60.3 cases per 10,000 DYAR, and also had the highest mortality rate of 46.7 per 10,000 DYAR (based on life insurance claims). Overall, males were at a higher risk than females (1.4:1). Median survival time (including euthanasia and death) after diagnosis was 1.5 years. In general, breeds kept solely for companionship lived longer after diagnosis than those kept for dual-purposes, such as hunting and shepherd and working breeds. The study demonstrates marked breed differences in incidence and mortality rates, which are assumed to reflect genetic predisposition to epilepsy.

A cohort study of epilepsy among 665,000 insured dogs: Incidence, mortality and survival after diagnosis

Background: A cat life insurance database can potentially be used to study feline mortality.



Hypothesis: The aim was to describe patterns of mortality in life-insured Swedish cats.



Cats: All cats (<13 years of age) with life insurance during the period 1999–2006 were included.



Methods: Age-standardized mortality rates (MR) were calculated with respect to sex (males and females), age, breed, and diagnosis. Survival to various ages is presented by time period and breed.



Results: The total number of cats insured was 49,450 and the number of cat-years at risk (CYAR) was 142,049. During the period, 6,491 cats died and of these 4,591 cats (71%) had a diagnosis, ie, were claimed for life insurance. The average annual MR was 462 deaths per 10,000 CYAR (95% confidence interval, 431–493). Sex-specific rates did not differ significantly. The overall mortality of the Persian and the Siamese groups was higher than that of several other breeds. Overall and breed-specific (for most breeds) survival increased with time when analyzed by 2-year periods. The 6 most common diagnostic categories (ignoring cats recorded as dead with no diagnosis) were urinary, traumatic, neoplastic, infectious, cardiovascular, and gastrointestinal. The MR within diagnostic categories varied by age and breed.



Conclusions and Clinical Importance: In this mainly purebred, insured cat population, the overall mortality varied with age and breed but not with sex. The increase in survival over time is likely a reflection of willingness to keep pet cats longer and increased access to and sophistication of veterinary care.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1939-1676.2009.0396.x

Mortality of Life‐Insured Swedish Cats during 1999–2006: Age, Breed, Sex, and Diagnosis

The primary aim of this article is to review the use of animal health insurance data in the scientific literature, especially in regard to morbidity or mortality in companion animals and horses. Methods and results were compared among studies on similar health conditions from different nations and years. A further objective was to critically evaluate benefits and limitations of such databases, to suggest ways to maximize their utility and to discuss the future use of animal insurance data for research purposes. Examples of studies on morbidity, mortality and survival estimates in dogs and horses, as well as neoplasia in dogs, are discussed.We conclude that insurance data can and should be used for research purposes in companion animals and horses. Insurance data have been successfully used, e.g. to quantify certain features that may have been hitherto assumed, but unmeasured. Validation of insurance databases is necessary if they are to be used in research. This must include the description of the insured population and an evaluation of the extent to which it represents the source population. Data content and accuracy must be determined over time, including the accuracy/consistency of diagnostic information. Readers must be cautioned as to limitations of the databases and, as always, critically appraise findings and synthesize information with other research. Similar findings from different study designs provide stronger evidence than a sole report. Insurance data can highlight common, expensive and severe conditions that may not be evident from teaching hospital case loads but may be significant burdens on the health of a population.

/pdf/insurance-data-for-research-in-companion-animals-benefits-57muniya26.pdf

Ane Nødtvedt

Papers

Canine perinatal mortality: A cohort study of 224 breeds

Litter Size at Birth in Purebred Dogs--A Retrospective Study of 224 Breeds

A cohort study of epilepsy among 665,000 insured dogs: Incidence, mortality and survival after diagnosis

Mortality of Life‐Insured Swedish Cats during 1999–2006: Age, Breed, Sex, and Diagnosis

Insurance data for research in companion animals: benefits and limitations