Dysostoses of the canine and feline appendicular skeleton

Cardiomyopathy associated 5 (CMYA5) implicated as a genetic risk factor for radial hemimelia in Siamese cats

OBJECTIVES

The present study aimed to determine the inheritance pattern and genetic cause of congenital radial hemimelia (RH) in cats.

METHODS

Clinical and genetic analyses were conducted on a Siamese cat family (n = 18), including two siblings with RH. Radiographs were obtained for the affected kittens and echocardiograms of an affected kitten and sire. Whole genome sequencing was completed on the two cases and the parents. Genomic data were compared with the 99 Lives Cat Genome data set of 420 additional domestic cats with whole genome and whole exome sequencing data. Variants were considered as homozygous in the two cases of the siblings with RH and heterozygous in the parents. Candidate variants were genotyped by Sanger sequencing in the extended pedigree.

RESULTS

Radiographs of the female kitten revealed bilateral absence of the radii and bowing of the humeri, while the male kitten showed a dysplastic right radius. Echocardiography suggested the female kitten had restrictive cardiomyopathy with a positive left atrial-to-aortic root ratio (LA:Ao = 1.83 cm), whereas hypertrophic cardiomyopathy was more likely in the sire, showing diastolic dysfunction using tissue Doppler imaging (59.06 cm/s). Twenty-two DNA variants were unique and homozygous in the affected kittens and heterozygous in the parents. Seven variants clustered in one chromosomal region, including two frameshift variants in cardiomyopathy associated 5 (CMYA5) and five variants in junction mediating and regulatory protein, P53 cofactor (JMY ), including a missense and an in-frame deletion.

CONCLUSIONS AND RELEVANCE

The present study suggested an autosomal recessive mode of inheritance with variable expression for RH in the Siamese cat family. Candidate variants for the phenotype were identified, implicating their roles in bone development. These genes should be considered as potentially causal for other cats with RH. Siamese cat breeders should consider genetically testing their cats for these variants to prevent further dissemination of the suspected variants within the breed.

Bilateral patellar agenesis in dog: A case report

A bilateral patellar agenesis is an extremely rare congenital condition in which the patient does not develop both patellas and can present secondary alterations as bone, muscle and postural changes. There are some hypotheses that it has a genetic background presenting dominant characteristic. It is not yet standardized a gold treatment for this affection, but according to rare reports, clinical and surgical treatments are possible. This is a case report based on imagining exams of a mix breed male puppy that was born with bilateral patellar agenesis, an affection not yet reported in canine species.

Four Unusual Cases of Congenital Forelimb Malformations in Dogs

Simple Summary

Congenital limb defects are sporadically encountered in dogs during normal clinical practice. Literature concerning their diagnosis and management in canine species is poor. Sometimes, the diagnosis and description of congenital limb abnormalities are complicated by the concurrent presence of different malformations in the same limb and the lack of widely accepted classification schemes. In order to improve the knowledge about congenital limb anomalies in dogs, this report describes the clinical and radiographic findings in four dogs affected by unusual congenital forelimb defects, underlying also the importance of reviewing current terminology.

Abstract

Four dogs were presented with thoracic limb deformity. After clinical and radiographic examinations, a diagnosis of congenital malformations was performed for each of them. In one case, a deformity involving both the radial and ulnar side of the distal limb was observed. Based on clinical and radiological evaluations, a diagnosis of postaxial terminal longitudinal ulnar hemimelia was performed. The term ectrodactyly was used to refer different malformations characterized by skin and soft tissue separation of the distal forelimb observed in two dogs. Simple complete uncomplicated syndactyly of the right forelimb, and complex incomplete uncomplicated syndactyly of the left forelimb were diagnosed in the fourth case. To the authors’ knowledge, ectrodactyly and simple complete uncomplicated syndactyly are very uncommon anomalies in companion animals and have been rarely documented. Moreover, postaxial terminal longitudinal ulnar hemimelia has still not been reported in dogs.

Surgical Ectrodactyly Repair Using Limb-lengthening and Bone Tissue Engineering Techniques in a Toy Dog Breed

BACKGROUND/AIM

Bone tissue engineering is an emerging field of regenerative medicine that holds promise for the restoration of bones affected by trauma, neoplastic diseases, and congenital deformity. During the past decade, bone tissue engineering has evolved from the use of biomaterials that can only replace small areas of damaged bone, to the use of scaffolds in which grafts can be seeded before implantation. This case report proposes an alternative option for a veterinary patient suffering from ectrodactyly, which is one of several congenital deformities in dogs. A 2-month-old male toy poodle dog with ectrodactyly was treated using several stages of surgery involving pancarpal arthrodesis, limb lengthening, and bone tissue engineering techniques.

RESULTS AND CONCLUSION

Over a period of 2 years, the operated limb gained almost the same function as the contralateral limb. Bone tissue engineering techniques can be used for the treatment of congenital deformities in dogs.

Presence of congenital anomalies in three dog litters

This report describes multiple congenital malformations found in three dog litters delivered by emergency caesarean section. In all of the litters, some puppies were born alive but were euthanized because of the seriousness of their malformations and low probability of survival. In two litters, gastroschisis was associated with amelia of the right anterior limb. Other malformations such as anencephaly were also found in three puppies among the different litters. This report describes the morphological findings of the affected puppies, discusses the most appropriate terminologies for each case and highlights the importance of an epidemiological survey to identify potential factors associated with the cases.

Disentangling Timing of Admixture, Patterns of Introgression, and Phenotypic Indicators in a Hybridizing Wolf Population

Hybridization is a natural or anthropogenic process that can deeply affect the genetic make-up of populations, possibly decreasing individual fitness but sometimes favoring local adaptations. The population of Italian wolves (Canis lupus), after protracted demographic declines and isolation, is currently expanding in anthropic areas, with documented cases of hybridization with stray domestic dogs. However, identifying admixture patterns in deeply introgressed populations is far from trivial. In this study, we used a panel of 170,000 SNPs analyzed with multivariate, Bayesian and local ancestry reconstruction methods to identify hybrids, estimate their ancestry proportions and timing since admixture. Moreover, we carried out preliminary genotype-phenotype association analyses to identify the genetic bases of three phenotypic traits (black coat, white claws, and spur on the hind legs) putative indicators of hybridization. Results showed no sharp subdivisions between nonadmixed wolves and hybrids, indicating that recurrent hybridization and deep introgression might have started mostly at the beginning of the population reexpansion. In hybrids, we identified a number of genomic regions with excess of ancestry in one of the parental populations, and regions with excess or resistance to introgression compared with neutral expectations. The three morphological traits showed significant genotype-phenotype associations, with a single genomic region for black coats and white claws, and with multiple genomic regions for the spur. In all cases the associated haplotypes were likely derived from dogs. In conclusion, we show that the use of multiple genome-wide ancestry reconstructions allows clarifying the admixture dynamics even in highly introgressed populations, and supports their conservation management.

Congenital deformity of the distal extremities in three dogs

Congenital limb deformities are very rare conditions and the knowledge about etiology, pathogenesis, clinical presentation and treatment is still poor. Moreover, many defects are still not reported in veterinary literature. This report documents clinical and radiographic findings in three dogs with congenital deformity involving the distal extremities. Case 1 was affected with bilateral aphalangia of the pedes, case 2 presented a combination of brachydactyly and syndactyly, whereas in case 3 a unilateral ectrodactyly was observed. To the authors’ knowledge, brachydactyly, as well as aphalangia, are very uncommon anomalies and have been rarely documented. Moreover, association between syndactyly and brachydactyly has still not been reported.

Bilateral tibial agenesis and syndactyly in a cat

CASE DESCRIPTION

A three-year-old cat was referred to the Veterinary Teaching Hospital, University of Naples, Italy. The cat had severe pelvic limb deformity, and abnormal development of all four paws.

CLINICAL FINDINGS

Radiographs revealed bilateral tibial agenesis, syndactyly, and digital hypoplasia.

TREATMENT AND OUTCOME

No treatment was instituted because of the severity of the injury, the adaptation of the cat to the abnormal condition, and the owner's refusal to permit any treatment.

CLINICAL RELEVANCE

Congenital limb deformities are rarely reported in the cat and tibial agenesis is considered a very rare disease. This congenital anomaly is well documented and classified in man, and it has been associated with other abnormalities in more complex syndromes. This paper reports clinical and radiographic findings in a cat affected by bilateral complete tibial agenesis associated with other congenital anomalies.

Case Report of Bilateral 3-4 Metatarsal Syndactyly in a Pet Rabbit

We report the first case of spontaneous syndactyly reported in a pet rabbit. Syndactyly only caused an atypical gait in the rabbit. The radiological study revealed bilateral 3rd and 4th metatarsal bones fused in its entire length preserving normal joint surfaces resembling syndactyly type Ia. The cause of this congenital malformation was unknown.

Congenital bipartite atlas with hypodactyly in a dog: clinical, radiographic and CT findings

A three-year-old Border collie was diagnosed with a bipartite atlas and bilateral forelimb hypodactyly. The dog showed signs of acute, non-progressive neck pain, general stiffness and right thoracic limb non-weight-bearing lameness. Computed tomography imaging revealed a bipartite atlas with abaxial vertical bone proliferation, which was the cause of the clinical signs. In addition, bilateral hypodactyly of the second and fifth digits was incidentally found. This report suggests that hypodactyly may be associated with atlas malformations.

Surgical induction of metacarpal synostosis for treatment of ectrodactyly in a dog

Ectrodactyly is a rare developmental anomaly of the distal part of the forelimb. It is characterized by the presence of an abnormal longitudinal soft tissue and osseous separation or cleft between the digits and the metacarpal bones. It can be associated with hypoplasia, aplasia and malformation of one or more bones of the antebrachium, carpus, metacarpus and digits. Unilateral ectrodactyly and moderate lameness were diagnosed in a young female dog. The dog was treated surgically with reconstruction of soft tissues and stabilization of the metacarpal bones by two nylon cerclage sutures. After three years a mild residual lameness was present. Radiographic signs of synostosis between the metacarpal bones II, III and IV with presence of a cleft between carpal bones II and III were observed.

Congenital deformity of the paw in a captive tiger: case report

BACKGROUND

The aim of this report was to describe the clinical signs, diagnostic approach, treatment and outcome in the case of a tiger with a deformity of the paw.

CASE PRESENTATION

A 1.5-year-old tiger (Panthera tigris) was presented with lameness of the left thoracic limb. A deformity involving the first and second metacarpal bones, and a soft tissue separation between the second and third metacarpal bones of the left front paw were observed. The second digit constantly struck the ground during locomotion. Based on the physical and radiographic evaluations, a diagnosis of ectrodactyly was made. A soft tissue reconstruction of the cleft with excision of both the second digit and distal portion of the second metacarpal bone was performed. Marked improvement of the locomotion was observed after surgical treatment, although the tiger showed a low degree of lameness probably associated with the discrepancy in length between the thoracic limbs.

CONCLUSION

This report shows a rare deformity in an exotic feline that it is compatible to ectrodactyly. Reconstructive surgery of the cleft resulted in significant improvement of limb function.

Bilateral radial hemimelia and multiple malformations in a kitten

Hemimelia is a congenital disease of complete or partial absence of one or more bones. The most important hypothesis is that radial agenesis is a consequence of neural crest injury. Treatment selection depends on the degree of the deformity and the reduction of limb function. This report describes a case of bilateral radial hemimelia and multiple malformations in a kitten aged 2 months treated conservatively with splint bandage, until bone maturity. The re-evaluation was performed 4 years later.

Bilateral ectrodactyly and spinal deformation in a mixed-breed dog

A 3-year-old, female mixed-breed dog had malformations of both thoracic limbs and the vertebral column. Radiographs of the forelimbs showed bilateral development of 2 digits and aplasia of 3 carpal bones. Kyphosis, scoliosis, and deformed vertebrae were present in the thoracolumbar vertebral column.

Syndactyly in a litter of cats

In this case report, we describe the clinical and radiographic features of a litter of kittens affected with complex syndactyly. We also provide guidelines for the diagnosis, possible treatment and prevention of propagation of this condition. This is the first report of syndactyly in a litter of kittens and syndactyly affecting both the pectoral and pelvic limbs.