Idiopathic Asymptomatic Thrombocytopenia in Cavalier King Charles Spaniels Is an Autosomal Recessive Trait

Abstract

Cavalier King Charles Spaniels (CKCS) often have idiopathic asymptomatic thrombocytopenia. In affected dogs, the thrombocytes often are large, and it has been speculated that the condition could be an inherited macrothrombocytopenia. The aim of this study was to examine the inheritance of idiopathic, asymptomatic thrombocytopenia in CKCS. Sixteen families (both parents and > or = 3 offspring) of privately owned CKCS were included. There were 105 clinically healthy dogs (50 from Denmark and 55 from Sweden): 81 offspring and 26 parents (2 dogs had both roles). Because autoanalyzers have difficulty counting large platelets, the platelets were counted manually, with a counting chamber. Platelet counts were not influenced by age, gender, or heart murmur status. Thrombocytopenia (< or = 100,000 platelets/microL) was found in 46% of the parents. The pedigrees indicated that thrombocytopenia segregated as an autosomal recessive trait and that 100,000 platelets/microL was appropriate as a lower limit of normal. Affected offspring were found in all families, showing that all of the included parents were at least carriers. Therefore, the expected segregation ratios (which were in good accordance with the observed ones) were 1:0, 1:1, and 1:3 for the 3 crosses: affected x affected, normal x affected, and normal x normal. Within a given cross, the mean parental platelet count had no influence on the platelet counts of the offspring. We conclude that idiopathic, asymptomatic thrombocytopenia in CKCS is inherited in an autosomal recessive manner. The condition most likely constitutes an inherited macrothrombocytopenia in dogs.

Breed-Specific Hematological Phenotypes in the Dog: A Natural Resource for the Genetic Dissection of Hematological Parameters in a Mammalian Species

“…However, the principal component thresholds of -2 and +2 were arbitrary and increasing them (for example to -3 and +3) would have increased the stringency of the analysis and disclosed fewer ‘unique’ breeds. Notwithstanding this caveat, several of the breeds identified by PCA were those with published hematological phenotypes – for example the shar pei [39], Rottweiler [17], CKCS [14] and greyhound [15,16]. Several other breeds had not previously been identified in the literature and were also highlighted in our pairwise comparisons.…”

“…The creation of distinct breeds has introduced remarkable genetic homogeneity, providing an unparalleled opportunity to dissect the genetic basis of complex traits: studies that would require thousands of human subjects typically require fewer than 100 in the dog [12,13], which is rapidly gaining traction as a model species in a number of biomedical disciplines. Certain hematological phenotypes have been recognized in dogs for many years [14-21], but no large-scale, systematic studies of the phenotypic diversity of peripheral blood in this species have been undertaken. Our objective was therefore to undertake a comparative analysis of normal hematological profiles within a large veterinary database in order to identify possible breed-specific phenotypes as a prelude to genetic analysis of these traits in the future.…”

Platelet Disorders

“…25 A mutation in β1-tubulin likely leads to altered proplatelet formation in megakaryocytes. 25 A mutation in β1-tubulin likely leads to altered proplatelet formation in megakaryocytes.…”

Letters to the Editor

“…Outcome measures have largely been interpreted through use of the five freedoms, 3 which focus on the avoidance of negative welfare states, and more recently via the five domains, 4,5 which accommodate and encourage consideration of positive states and focus on attainable goals. Outcome measures have largely been interpreted through use of the five freedoms, 3 which focus on the avoidance of negative welfare states, and more recently via the five domains, 4,5 which accommodate and encourage consideration of positive states and focus on attainable goals.…”

“…3 As an enticement, colleges could use private money to support tuition discounts, bursaries, and scholarships in exchange for contractual agreements from students willing to make a set commitment (eg, 3 to 5 years) in an underserved practice sector. Companion animal practice is the choice for most new veterinary graduates, at the expense of other sectors such as food animal practice, public health, and governmental and corporate practice.…”