Post mortem magnetic resonance imaging of multiple congenital ocular anomalies in a Comtois mare

Multiple congenital ocular anomalies syndrome consists of several abnormalities mainly localised to the anterior segment of the eye. This condition, comprising iridal or ciliary cysts with or without iridal hypoplasia, an excessively protruding cornea (‘cornea globosa’), miotic pupils, retinal dysplasia, cataract, and other lesions, has been reported in several breeds and is strongly related to the silver coat colour, as a result of a dominant mutant allele at the PMEL17 locus. This report describes the macroscopic, ultrasonographic, histological and magnetic resonance imaging findings of the ocular abnormalities in a Comtois mare with multiple congenital ocular anomalies syndrome.     

Congenital ocular anomalies in purebred and crossbred Rocky and Kentucky Mountain horses in Canada

Multiple congenital ocular anomalies in purebred and crossbred Rocky and Kentucky Mountain horses in Canada are frequently diagnosed with biomicroscopic and indirect ophthalmoscopic examination. In order of frequency detected, these include temporal ciliary epithelial cysts; iridal hypoplasia; prominent corneas; focal temporal retinal degeneration related to ciliary cysts; and, rarely, retinal detachment. A pedigree analysis confirms a dominant mode of inheritance with incomplete penetrance and with a linkage to coat color.     

Phenotypic description of multiple congenital ocular anomalies in Comtois horses

Multiple congenital ocular anomalies (MCOA) and their relation to coat colour genotype have not yet been described in Comtois horses, unlike in Rocky Mountain Horses. The objectives of the study were to describe prevalence, nature and severity of congenital ocular anomalies relating to the PMEL17 (Silver) mutation in Comtois horses. Seventy‐four purebred Comtois and one half‐cross Comtois horses, aged 10 days to 18 years, were examined by transillumination, direct ophthalmoscopy and ultrasonography. Hair samples were collected from 34 horses for coat colour genotyping. Sixty‐six horses (88%) revealed cysts (65 horses) or abnormal thickness (one horse) of the ciliary bodies, most of them only diagnosed by ultrasonography. Cysts were localised in the nasal part of the eye in 8 horses. All these horses presented the silver phenotype with mane and tail being white or flaxen, or were chestnut with genetic testing confirming PMEL17 mutation. Of these, 39 (58%) showed MCOA‐syndrome with iridal hypoplasia (100%), cataract (85%), cornea globosa (56%) and lens luxation (8%). Only 8 bay mature horses (11%) were classified as being disease‐free. Genetic testing confirmed that cyst‐phenotype horses were heterozygous carriers for the Silver mutation, MCOA‐phenotype horses were homozygous carriers, and bay horses were noncarriers. Bay homozygous carriers had significantly lighter coat colour than heterozygous carriers. One foal with heterozygous mutation had normal eyes. Thus, MCOA‐syndrome related to PMEL17 mutation is overrepresented in Comtois horses, and should be taken into consideration for breeding purposes. Ultrasonography permitted detection of cysts in all Silver carriers apart from one, some of them being localised in the nasal part of the eye.     

Congenital odontogenic keratocyst in a filly

This report describes a congenital odontogenic keratocyst in the left mandible of a filly. A definitive diagnosis was only made after histopathological examination. Mandibular cysts of odontogenic and osteogenic origin have been reported in the past but a case of a keratocyst has not been previously reported in the horse.     

Congenital abnormalities of the feline vertebral column.

Radiographs of vertebral segments from 200 cats were retrospectively assessed to determine the incidence of congenital axial skeletal abnormalities. The axial skeleton was divided into cervical, thoracic, lumbar, sacral, and caudal segments and the presence and types of congenital abnormalities present were recorded for each segment. A total of 598 axial skeletal segments were examined. Congenital abnormalities were found in 46 cats and involved 54 spinal segments. Block vertebrae were identified in three cats. No hemivertebrae or spina bifida were noted. Transitional abnormalities were most common, and were identified in 51 spinal segments. Abnormalities at the sacrocaudal junction were the most common of these; 19 examples were found. The second most common transitional abnormality was thoracicization of L1, with 18 such cats identified. Extra ribs on L1 were often smaller and fragmented and it may be possible for an inexperienced clinician to confuse these with rib fractures. The last rib(s) are also often used for anatomic localization of surgical procedures; the presence of a transitional lumbar vertebra with one or two extra ribs introduces the possibility of error or confusion about choice of surgical site.     

Survey of ocular abnormalities in draft horses

Objective

To determine the prevalence of ocular disease in draft horses in the United States.

Animals

Draft horses of various breeds and ages.

Procedure

Nondilated ophthalmic examination was performed using slit lamp biomicroscopy and indirect ophthalmoscopy. Intraocular pressures were measured when possible.

Results

One hundred sixty-five draft horses were examined. Age range: 10 days to 33 years (mean 10.8 years, median 10 years); 87 geldings (52.7%), 71 mares (43.0%), 7 stallions (4.2%); 64 Percherons (38.8%), 51 Belgians (30.9%), 29 Clydesdales (17.6%), 15 Shires (9%), and 6 other draft breed (3.6%). Intraocular pressure: mean 24.7 mmHg OD, range 13-37 mmHg; mean 25.0 mmHg OS, range 11-37 mmHg. Vision-threatening disease was present in 9 horses (5.5%): complete cataracts 1, post-traumatic optic nerve atrophy 1, uveitis and secondary glaucoma 1, retinal detachment 1, large chorioretinal scar 3, phthisis bulbi 2. Non-vision-threatening ocular disease was present in 56 horses (33.9%) involving one or more ocular structures: eyelid trauma/notch defect 14 (8.5%), SCC-type adnexal lesions 12 (7.3%), corneal scars 16 (9.7%), keratitis 6 (3.6%), corpora nigra cyst 15 (9.1%), incipient/punctate cataract 50 (30.3%), vitreous degeneration 10 (6.1%), asteroid hyalosis 1, “bullethole” chorioretinal scars 3, RPE coloboma 1. Linear keratopathy was present in 28 horses (17%) with 2/28 having concurrent vision threatening ocular disease.

Conclusions

Ocular abnormalities, in particular minor cataracts, were relatively common in this population, but not typically vision-threatening. Additionally, this survey demonstrated a greater prevalence of linear keratopathy in draft horses compared with reports in other breeds; however, it does not appear to be associated with concurrent ocular disease.     

Delayed metastasis of ocular squamous cell carcinoma following treatment in five horses

Identification of regional and/or distant metastasis following treatment and local resolution of primary ocular squamous cell carcinoma (SCC) was observed in 5 horses. In all cases, identification of metastasis occurred at least 18 months following treatment of the primary ocular lesions. In 3 cases, invasion of blood or lymphatic vessels by neoplastic cells was identified in the excisional biopsies of the primary tumour. Two horses developed SCC at 2 or more separate sites. At the time metastases were identified, there was no evidence of local recurrence of the ocular tumour in any of the horses. These cases confirm the importance of long‐term monitoring of horses for metastatic disease following treatment of ocular SCC even in the absence of local recurrence.     

Multiple congenital ocular anomalies syndrome in a family of Shetland and Deutsches Classic ponies in Belgium

The multiple congenital ocular anomalies (MCOA) syndrome has been associated with the Silver phenotype only in a few equine breeds. This report describes the phenotypic and genotypic characteristics of MCOA in a family of Silver‐coated Shetland ponies including a 20‐year‐old stallion, 17‐year‐old mare and their 1.5‐year‐old female offspring. Another 7‐year‐old Silver female Deutsches Classic Pony descending from the same dam but from a different sire, was also examined. Each pony underwent a complete ophthalmic examination, tonometry, ocular ultrasonography and genotyping for the silver coat colour. The stallion had a thickened iris, temporal retinal atrophy and bilateral iridociliary and peripheral retinal cysts. All females presented more severe anomalies: cornea globosa, iridocorneal adhesions, miosis, hypoplastic granula iridica and poorly responsive pupils to light and to pharmacological mydriasis. Iris hypoplasia, anterior cortical cataracts and temporal retinal atrophy were detected in 2 mares. One female presented bilateral lens subluxation. Supero‐temporal cystic structures were confirmed ultrasonographically in all ponies. The stallion was heterozygous for the Silver mutation, whereas all females were homozygous. This is the first report of the MCOA syndrome in a family of Shetland ponies and a Deutsches Classic Pony in association with the Silver phenotype, in Europe.     

Congenital limb abnormality in a Thoroughbred foal in Trinidad

A congenital defect of the right hindlimb of a 36‐h‐old Thoroughbred foal as reported for the first time in Trinidad, West Indies. The foal was subjected to euthanasia and radiographs of both hindlimbs revealed that the bones distal to P1 of the right hindlimb only, were missing. Insertion of both the superficial and deep digital flexor tendons were found to be on the most proximal aspect of P1. Necropsy revealed no other congential defects.     

Congenital bilateral aplasia of the metacarpophalangeal joints in a foal

A 2‐day‐old Warmblood filly was presented for examination of an angular limb deformity of the left front limb and an upright conformation of both metacarpophalangeal joints. Radiological examination revealed bilateral absence of the metacarpophalangeal joint space with fusion of the third metacarpal bone and first phalanx (synostosis). No treatment was undertaken. The filly was readmitted to the clinic 10 weeks later for bilateral front limb lameness. On radiological examination, the synostosis of the front metacarpophalangeal joints was still present. Physitis of the distal growth plate of the right third metacarpal bone and proximal growth plate of the right proximal phalanx, and an avulsion fracture of the palmaromedial and proximal aspect of the left middle phalanx, with a cystic like lesion on the medial aspect of distal first phalanx and proximal middle phalanx were diagnosed. Given the poor prognosis, the foal was subjected to euthanasia. Post mortem examination confirmed the absence of the metacarpophalangeal joint space with a trabecular bony union between the third metacarpal bone and the first phalanx. A rudimentary joint capsule was present at the level of the absent joints as well as a small zone of articular cartilage, which invaginated over a short distance into the dorsal trabecular bone on the right front limb. On the medial aspect of the left proximal interphalangeal joint, a focal defect of articular cartilage with exposure of subchondral bone was observed. This is the first case report of a foal born with congenital aplasia of both metacarpophalangeal joints. Congenital malformations should be considered as differential diagnosis in lame foals or foals born with angular or flexural limb deformities.     

Congenital hypoplasia of the dorsal colon in a Quarter Horse filly with chronic,intermittent colic

Congenital colonic anomalies are rare in the horse and, to the authors' knowledge, no cases have been reported that include measurements of each segment of the large colon to confirm which section is abnormal. This case report describes chronic, intermittent colic in a Quarter Horse filly that had been attributed to chronic idiopathic hepatitis prior to an exploratory laparotomy. A colonic anomaly discovered at surgery became the primary differential for aetiology of the intermittent colic. Euthanasia of the filly and necropsy allowed further examination of the anomaly, where it was determined that the dorsal colon was short compared to the ventral large colon. In addition, the diagnosis of chronic idiopathic hepatitis was confirmed.     

Congenital oesophageal stricture in an Arabian filly treated by balloon dilation

Congenital oesophageal stricture was diagnosed via endoscopy in a 3‐day‐old Arabian filly suffering from nasal milk regurgitation. Vascular ring anomaly or other extramural, intramural or intraluminal causes were not identified on radiographs or on a computed tomography scan; thus a functional abnormality was suspected. The filly was treated with antibiotics for aspiration pneumonia and was fed milk through an indwelling nasoesophageal tube. Two sessions of balloon bougienage at the stenotic site, under sedation, resulted in marked clinical improvement and thereafter the filly was gradually reintroduced to suckling from the mare. The filly was discharged from the hospital after 17 days and on follow‐up there were no reports of food regurgitation even after the introduction of solid food. The filly was still doing well in the latest follow‐up at age 11 months.     

三河马血红蛋白的遗传多态性

采用等电聚焦电泳对25匹三河马进行了血红蛋白多态性的检测，结果表明：该位点共发现有4种基因型，由3个等位基因HbT^BⅡ、HbBIt Hb^AⅡ控制，基因型BⅡ/BⅡ、BI/BⅡ、Bi/BI和AⅡ/BⅠ的频率分别为0.08,0.52,0.36和0.04，其中杂合型BI/BⅡ为优势基因型，等位基因Hb^BⅡ、Hb^BI和HbA^Ⅱ的频率分别为0.34,0.64和0.02。基因杂合度、个体识别概率和亲仔关系排除概率分别为0.47,0.59和0.20。