Statistical analysis in support of maintaining a healthy traditional Siamese cat population

Background For many years, breeders of companion animals have applied inbreeding or line breeding to transfer desirable genetic traits from parents to their offspring. Simultaneously, this resulted in a considerable spread of hereditary diseases and phenomena associated with inbreeding depression. Results Our cluster analysis of kinship and inbreeding coefficients suggests that the Thai or traditional Siamese cat could be considered as a subpopulation of the Siamese cat, which shares common ancestors, although they are considered as separate breeds. In addition, model-based cluster analysis could detect regional differences between Thai subpopulations. We show that by applying optimal contribution selection and simultaneously limiting the contributions by other breeds, the genetic diversity within subpopulations can be improved. Conclusion In principle, the European mainland Thai cat population can achieve a genetic diversity of about 26 founder genome equivalents, a value that could potentially sustain a genetically diverse population. However, reaching such a target will be difficult in the absence of a supervised breeding program. Suboptimal solutions can be obtained by minimisation of kinships within regional subpopulations. Exchanging animals between different regions on a small scale might be already quite useful to reduce the kinship, by achieving a potential diversity of 23 founder genome equivalents. However, contributions by other breeds should be minimised to preserve the original Siamese gene pool.

Siamese cat tyrosinase has enhanced proteasome degradation and increased cellular aggregation

Siamese cats are a notable example of a temperature-sensitive partial albinism phenotype. The signature color-pointing pattern is the result of an amino acid substitution – G302R – in the cysteine-rich domain of feline tyrosinase. The precise mechanism for the loss of tyrosinase enzyme activity due to this mutation is unknown.ObjectiveWe have used a cellular biology approach to begin unravel relationships between feline coloration, behavior and increased risk for feline cognitive dysfunction syndrome. GFP-fusion constructs of wild type domestic short hair tyrosinase and Siamese (G302R) tyrosinase generated to study cellular trafficking, degradation and the propensity for cellular aggregation.Data DescriptionC-terminal GFP G302R expression has reduced Golgi localization, increased cytosolic fractions with reduced calnexin co-localization. N-terminal GFP constructs were retained in the ER, with little to no Golgi associated forms. C-terminal and N-terminal GFP G302R TYR is observed to have increased high molecular weight aggregation following proteasome inhibition.

Baboon bearing resemblance in pigmentation pattern to Siamese cat carries a missense mutation in the tyrosinase gene

An infant hamadryas baboon exhibiting an albino phenotype—white body hair and red eyes—was born to parents with wild-type body color. Pigmentation on some parts of its body surfaced during childhood and progressed with age. This baboon in adulthood has gray hair on parts of its body, such as the tail, distal portion of the legs, and face, with the remainder being white. This pigmentation pattern resembles that of the Siamese cat and the Himalayan variants of the mouse and the mink. The distinguishing phenotypes in these animals are known to be caused by a temperature-sensitive activity of tyrosinase, an enzyme essential for biosynthesis of melanin. We sequenced all the five exons of the tyrosinase (TYR) gene of this albino baboon, which were amplified by PCR, and found a base substitution leading to alteration of the 365th amino acid from Ala to Thr. Tyrosinase requires copper as a cofactor for its enzyme function. It has two copper-binding sites, the second of which contains His residues in positions 363 and 367 that are critical to its function. Thus, p.(Ala365Thr) due to a mutation in the TYR gene is a likely candidate for the cause of the albino phenotype in this baboon.

Surgical Management of Bicornual Uterine Prolapse in a Siamese Cat: A Case Report

Uterine prolapse is a rare condition in cats that can be managed by performing either an external hysterectomy or manual reduction followed by ovariohysterectomy. This article describes surgical management of bilateral uterine prolapse in a queen. A one year old female, pluriparous Siamese cat (Felis catus) with no past history of dystocia and weighing 2.8 kg was presented to Andys Veterinary hospital, Nairobi, Kenya with a protruding mass through the vulval. The queen had a history of recent queening and had delivered three kittens a week earlier. The owner noticed the protruding mass about 24 hours after the delivery of the last neonate. A few days later, the cat was not suckling the kittens well and was in appetent. As a sequel to this, two kittens died. After a week, the protruding mass had a pungent smell and the client presented the cat to the hospital. Complete bilateral uterine prolapse was diagnosed after a visual examination and palpation of the mass. The uterus was swollen, had necrotic areas and debris. Accordingly, a two staged ovariohysterectomy was opted for to manage the case. An internal ovariectomy was first done via a ventral midline celiotomy followed by an external hysterectomy. Post-operative management included pain medication and antibiotic therapy and the patient recovered well and was discharged after 2 days. The skin sutures were removed 10 days postoperatively. The cat recovered uneventfully with no further complications reported by the owner. In conclusion, this article shows that when the prolapsed uterus is swollen, damaged and necrotic, a two staged ovariohysterectomy should be the method of treatment and the outcome is good despite the duration of the condition.

Dermoid sinus in the perirectal fossa of a Siamese cat with involvement of the vaginal wall

A 2.5-year-old spayed female Siamese cat was presented with a recurrent exudative wound in the right perirectal fossa. Clinical examination at presentation revealed a 1 cm long open wound with purulent discharge in the right perirectal fossa but was otherwise unremarkable. A computed tomography contrast-enhanced study showed a tracking sinus which could be traced from the right dorsolateral perianal region right up to the level of the vagina. Surgical exploration was performed from the perirectal region. The intermuscular sinus tract, which formed a cystic structure and connected to the vaginal wall, was en bloc excised. Histopathological examination confirmed the diagnosis of a dermoid sinus in the perirectal fossa with vaginal infiltration. To the authors’ knowledge, this is the first case report in the veterinary literature of the successful surgical management of a dermoid sinus in the perianal region connected to the vaginal wall in a cat.

Fibrosarcoma arising after femur osteosynthesis with pin and plate placement in a cat

A 6-year old spayed female Siamese cat was presented with a history of left limb acute lameness. Radiographic imaging revealed a complete comminuted diaphyseal femur fracture, which was corrected through intramedullary pin placement along with plate osteosynthesis. After two months the animal returned to the hospital presenting severe diffuse enlargement of the left hindlimb, characterized as a non-delimited, solid, and firm plaque-like mass surrounding the pin and bone, which extended from the femorotibiopatelar joint to the pelvis, and infiltrated the adjacent musculature. Incisional biopsy exam indicated a highly malignant sarcoma. The entire limb was surgically removed and sent to histopathological evaluation. Microscopically, the mass was composed of spindle shaped cells, displaying high pleomorphism and cellular atypia. Abundant collagen production was evidenced through Masson's trichrome stain and strong cytoplasmic staining for vimentin. These results were consistent with fibrosarcoma. The cat went through one session of chemotherapy; however, tumor recurrence occurred 20 days later, and the animal was submitted to euthanasia. This is the first description of fibrosarcoma arising in the vicinity of an intramedullary pin and plate in a cat.