As a practitioner, one sees many fascinating breeds of cats pass through the doors, but their rarity compared with the general domestic shorthair and longhair cat population makes it difficult for veterinarians to stay up-to-date and be fully informed about all cat breeds. The breeds themselves are evolving quickly, as they are under perpetual development. Breeders select for characteristics that evolve quite quickly as standards are updated or expanded, and the set of new provisional or now extinct breeds also changes.
Accessing relevant information not only about the abnormalities that may afflict each breed, but about what is normal for that breed can be a time consuming task since literature about cat breed-related problems is sparse, and very widely dispersed. Many reports are found in journals outside the normal spectrum of practitioner subscription journals. Reviews in clinical practice journals tend to be tables of conditions, with limited depth of coverage of the conditions.
The scope of this resource is to provide only breed-related information-not general medicine and surgery, or treatment and does not cover detailed coat color genetics. Resources are provided in the appendix and reference lists for those wishing to access detailed material.
Note that different cat registries have disparate standards, and geographic variation within these standards occurs. Generic breed descriptions in the chapters have therefore been loosely based on the CFA standard, with detailed comparisons between registries being absent due to space constraints. Due to the fact that if a reader is in a part of the world where other registry standards predominate, referring to the local registry standard is recommended. Variations between registry standards are very complex, and can be significant, even to the point of different breed names, different categories and varieties being recognized, different conformation accepted, and different details of coat color, texture, and pattern distribution preferred.
Likewise, as far as specific breed origins, many different “stories” can be found in published reports. The summaries supplied herein are aggregated from many sources, relaying what could to be the most widely accepted “theory”. The interpretation of history may be flawed, and in many cases, it appears a lack of accurate historical documentation exists. This means that for some breed origins, we will never likely know the “real” story. New genetic tools are also changing the way we look at breed origins, and as new information accrues, it is likely some of the stories will give way to the new evidence.
The scope of this website encompasses the clinical signs and anticipated age of onset, progression, prognosis and cursory discussion of particularly helpful diagnostic tests. Where the scope of the tests is outside the standard minimum database, or selection or interpretation of those tests is non-standard, we have noted such.
Unfortunately for the cat world, support for research is sparse except when animal models of human disease apply. There is a dearth of studies reported since the 1980s, though recently with private funding bodies like the Winn Feline Foundation and American Association of Feline Practitioners supporting important projects, a new surge in research is now occurring. Advances in genetic technology provide new tools such as gene sequencing, with linkage and gene testing. These have inspired a new generation of researchers and provided new power for carrier detection. Still, when compared with dogs, there is very little available in the literature. Big holes are especially obvious in the rare breeds.
A weakness of reporting in the primary literature is the inconsistent definition of breed names. For example, Domestic Shorthair is sometimes used interchangeably with American Shorthair and British Shorthair if registration is not relayed in the signalment portion of the study. Since American Shorthair breed cats used to be called Domestic shorthair, older reports may actually refer to registered cats. If a study does not include “pedigreed” or “registered” in the content of the report, these were excluded from the present data gathering since the purebred and domestic population gene pool is now different because registries have been closed for quite a while. Some older references that dealt with American Shorthair (formerly Domestic Shorthair) will have thus been passed over. Breeds where color groups or hair coats have become breeds of their own in some registries also complicate study assignment to a breed. Scottish Fold/Highland Fold, Persian/Himalayan, Manx/Cymric are some examples.
Few formal breed-wide surveys have been done in cats, though recent efforts to gather breeder data into a larger database in the field have been carried out. Keeping data secure and protecting identity is often necessary for wide survey acceptance. Statistical significance which can be useful for management of breeding stock is still rarely generated. Breeder surveys are generally not statistically rigorous, and in evidence-based medicine not as high a level of significance, so results should be considered “getting a finger on the pulse” of a problem, rather than providing hard and fast data.
Another point to note is that much data from research colonies has been reported, with efforts at extrapolation; these populations are closed and do not necessarily reflect the wider picture in a breed. Establishing breed “normals” has just begun.
Many disorders have been documented in purebred or DSH/DLH cats. Some, like polycystic kidney disease in Persian and Persian-related cats, account for a major proportion of genetic disorders in the general registered cat population, others are only found in rare case reports. Rare conditions are often found in early literature, and may seemed to have apparently dropped out of existence since the report, but perhaps have undergone an insidious silent spread if not widely recognized.
If the veterinarian does not know about these rare cases, inevitably, the condition will not be widely recognized and diagnosed. The decision to place rare reports in our chapters was based on the need for the practitioner to be aware of their possible existence and to provide sources for research about these rarely reported conditions. Inclusion of these does not implicate it as a “breed problem” per se.
Lack of reported disorders in a chapter does not imply that those problems are not found in the breed, it just reflects the lack of reports-or the fact that is not a particularly breed-specific disorder. Conversely, a plethora of reports in a chapter does not necessarily correlate with an unhealthy breed, or a high prevalence of reported conditions, but may just reflect the reality that a breed is popular, therefore populous, and more literature reports are thus generated.
Many conditions are not breed specific and thus not covered in detail in this reference. Readers are referred to general feline and internal medicine texts to garner more information on those conditions.
The proportion of purebreds in the cat population is still lower than in dogs (cats are ratio of about 1 registered: 5 unregistered), so overall in practice one still sees more infectious and trauma cases than genetic disorders in cats. Nevertheless, newer studies are starting to point to genetically determined susceptibility to certain immune and infectious conditions (autoimmunity, FIP susceptibility, certain cancers) so inherited “disorders” are in fact, much more pervasive than was previously thought.
It remains difficult in some conditions to distinguish between congenital and inherited, versus environmental or acquired (nature versus nurture) etiologies. Thus, dividing these conditions by cause is somewhat arbitrary, and some breed conditions may need to be moved from the Disease Predispositions to the Inherited Diseases section or vice versa as further research elucidates these problems.
It is important to know about inherited disorders since many breeds of cats are genetically closed and suffer from reduced genetic diversity. It is important to identify and correctly manage these disorders in order to preserve genetic diversity without perpetuating harmful genetic conditions, and each veterinarian needs to understand and embrace proper genetic counseling.
Breeding closely to embed desirable genetic constitution can also co-select for rare mutations or polygenic traits that can be amplified within a line or a breed. Removal of undesirable genetic traits must be a gradual process so that strong genetic lines are not lost or compromised. Long-term commitment by breeders and the health care team is needed to properly manage such disorders from a population medicine point of view.
Newer advances in molecular biology allow linkage marker identification, definitive gene sequencing, and PCR-based genetic testing that can identify carriers at any age with non-invasive tests. These new advances are helping breeders and veterinarians make informed choices. This technology is a double edged sword though, and these powerful aids to selection must be applied intelligently. See the section from Dr. Bell on genetic counseling to review appropriate management recommendations for breeders.
Not every cat breed is included in the first edition, and as the website is updated, adjustments and additions will need to be made in order to keep the listing current. Readers are encouraged to send comments to help us update the cat breed section. Use the contact address provided in the website preface. Chapters are in alphabetical order.
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