Genetic Eye Disorders in
Cavalier King Charles Spaniels

Overview

The cavalier King Charles spaniel has more than its fair share of severe genetic diseases afflicting the eye.* A 2008 study of cavaliers conducted by the Canine Eye Registration Foundation showed that an average of 28% of all CKCSs evaluated had eye problems.

* See, American College of Veterinary Ophthalmologists (ACVO) and Ophthalmic Disease in Veterinary Medicine.

They include hereditary cataracts, corneal dystrophy, corneal ulcers, distichiasis, dry eye syndrome, entropion, microphthalmia, progressive retinal degeneration, retinal dysplasia, and cherry eye , all of which are discussed on this website. Other hereditary eye disorders, of more minor nature, are not discussed.

In our Veterinary Resources section below, we also include citations to veterinary journal articles on other vision disorders for which cavaliers have been treated, including  reticulosis and Ehlers-Danlos syndrome.

In many instances, the eye disorders CKCSs experience may be attributed to the brachycephalic shape of their heads. Also, in a November 2016 article, UK ophthalmologists found that the size of the eyes of the cavalier, which is classified by kennel clubs as  a small dog, was larger than other small dogs and fit within the eye size of medium sized dogs.

All cavaliers should be examined at least annually by a board certified veterinary ophthalmologist. They are listed on this webpage of the website of the American College of Veterinary Ophthalmologists.

Eye

 

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List of Eye Disorders

The cavaliers' eye disorders include the following. Click on them to be directed to our articles about them.

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Glaucoma

Glaucoma eyeGlaucoma is a neuro-degenerative disease in which the retinal ganglion cells begin to die and the optic nerve degenerate. It is one of the leading causes of blindness in dogs. Canine glaucoma is generally classified as either primary or secondary. In primary glaucoma, intraocular pressure (lOP) increases through a reduction in aqueous fluid drainage due to hereditary abnormality. The most frequent causes of secondary glaucoma include lens displacement, anterior uveitis, intraocular neoplasia, postcataract surgery, and trauma. The cause of the elevated lOP is generally assumed to be the obstruction of the aqueous humor outflow pathways. We have found these articles in which cavalier King Charles spaniels have been diagnosed with glaucoma: September 2006, March 2011, November 2016.

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Heartworm -- Angiostrongylus vasorum in the eye

The heartworm Angiostrongylus vasorum is a parasitic nematode that lives in the pulmonary vessels and the heart of dogs.  A higher occurrence of this parasite has been found in cavaliers than other breeds, and especially in the cavaliers' eyes as well as the heart and blood vessels.  See these veterinary reports for details about this disorder in CKCSs: June 1994, 2004, March 2016.

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Keratitis

Keratitis is an inflammation of the cornea, the anterior part of the eye which covers the pupil. Corneal inflammations can be caused by bacteria, fungus or virus – but whatever the agent the cornea is going to present some quite nasty symptoms. Keratitis sicca is also known as "dry eye syndrome", which we cover separately at its own webpage.

We have found two veterinary journal articles describing the diagnoses and treatments of cavaliers with keratitis infections. Both of them included surgeries. Keratomycosis - AfterKeratomycosis - BeforeIn this September 2015 article, a cavalier was among five dogs with keratomycosis, an infection in the cornea caused by a fungus. Due to the severity of the infection, a keratectomy (corneal surgery) and conjunctival graft surgery were successfully performed. See the before (left) and after (right) photos of this cavalier's eye.

In this June 2016 article, a cavalier was one of six dogs and two cats studied. The CKCS had infectious crystalline keratopathy (ICK) in its cornea. An anterior lamellar keratectomy and a corneoconjunctival transposition surgical procedure were successfully performed.

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Related Links:

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Ocu-GLO RxWhat You Can Do:

 Ocu-GLO Rx is a nutraceutical containing several natural antioxidants in a combination blend formulated specifically for canine eye health. Many veterinary ophthalmologists recommend this product to maintain healthy eyes. Even if your dog has not been diagnosed with a vision disorder, antioxidants contained in Ocu-GLO Rx are considered helpful in keeping dogs' eyes healthy.

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Research News:

November 2016: Cavalier eye sizes are large for small dogs but fit in the medium dog group. In a November 2016 article, UK ophthalmologists (Carolin L. H. Chiwitt, Stephen J. Baines, Paul Mahoney, Andrew Tanner, Christine L. Heinrich, Michael Rhodes, Heidi J. Featherstone) found that the size of the eyes of the cavalier King Charles spaniel, a small dog, was larger than other small dogs and fit within the eye size of medium sized dogs. The researchers measured the eye sizes of 100 dogs in ten breeds, incuding 10 cavalier King Charles spaniels.

The three different measurement planes of the eye which the researchers used are the sagittal, the equatorial, and the horizontal, as this figure shows:Ocular Biometry

The researchers used both B-mode ocular ultrasound and computed tomography (CT) to do so in a procedure called "ocular biometry", which is the measurement of the dimensions of the eye, its components, and their interrelationships. They divided the 100 dogs into three size groups -- small, medium, and large based upon the UK Kennel Club assignments -- and placed the CKCS in the small dog group. They measured eye length, width, and height using the both of the devices -- ultrasound and CT.

They found that the CKCS had a relatively large eye for the small breed group, and there was no significant difference between the CKCS eye and those in the medium breed group. They also found that their measurements using both B-mode ultrasound and CT can be applied for the diagnosis of microphthalmos and buphthalmos.

November 2016: Brazilian researchers use digital video imaging to determine eye blink rates in cavaliers. In an October 2016 abstract, a team of Brazilian ophthalmologists (GV Fontinhas Netto, AR Eyherabide, AP Ribeiro, AA Bolzan) used digital video imaging to determine the eye blink rates per minute (EBR) in eleven healthy cavalier King Charles spaniels. They found no significant difference between the left and right eyes, and the mean value of EBR was 9.6 blinks/minute. They also measured the central corneal sensitivity by evaluating the corneal touch threshold (CTT) with the Cochet-Bonnet aesthesiometer, and tear production using the Schirmer tear test 1 (STT1). Mean ± SD tear production was 24.1 ± 1.6 mm/minute and CTT was 1.7 ± 0.3 cm. All tests were performed without anesthetic eye drops.

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Veterinary Resources:

Reticulosis of the eyes and the central nervous system in a dog. NL Garmer, P Naeser, AJ Bergman. J.Small Animal Prac.; Jan. 1981;22(1):39-45. Quote: "Bilateral optic neuritis was diagnosed in a 5-year old dog, which had been blind for two days. ... CASE REPORT A 5-year old, 10 kg, male Cavalier King Charles Spaniel was examined because the dog had appeared blind for two days. ... Vision returned after corticosteroid therapy. Two weeks after the end of this treatment the dog became blind again and, in addition, showed ataxia. Post-mortem examination revealed changes in both the central nervous system and the eyes. The histopathological changes observed were consistent with those of reticulosis.

Ehlers-Danlos syndrome in a dog: ocular, cutaneous and articular abnormalities. KC Barnett, BD Cottrell. J.Small Animal Prac. - Journal of Small Animal Practice; Oct. 1987;28(10):941-946. Quote: "Ehlers-Danlos syndrome (EDS) is an hereditary connective tissue disease in man in which the skin is easily torn. A similar condition has been described in dogs and other animals. This case report records a case in the United Kingdom in which the whole syndrome was exhibited: skin fragility, joint laxity and ocular signs of bilateral lens luxation, cataract and corneal oedema. It is the first report of ocular signs in EDS in the dog and joint laxity has been reported only rarely. ... A crossbred bitch (Cavalier King Charles Spaniel x Rorder Collie bitch) was presented at the age of 12 months for investigation of failing vision. ... The case reported here was a Cavalier King Charles Spaniel x Border Collie; neither breed has previously been implicated."

Angiostrongylus vasorum in the anterior chamber of a dog's eye. M. C. A. King, R. M. R. Grose, G. Startup. J. Small Anim. Prac. June 1994;35:326–8. Quote: "An unusual case of Angiostrongylus vasorum infestation occurred in a three-year-old female cavalier King Charles spaniel. The dog presented with signs consistent with right otitis interna, followed by the appearance of a free-swimming nematode in the anterior chamber of the right eye. The dog died of acute heart failure before surgical removal of the parasite was possible. Post mortem examination confirmed the presence of large numbers of worms in the pulmonary artery and right ventricle. These worms were identified histologically as A vasorum." Age, sex and breed: 3-year-old female Cavalier King Charles Spaniel. Location: UK. Clinical presentation: Otitis interna, head tilt, submaxillary lymph node enlargement. Presence of a motile worm in the anterior chamber of the eye on a one-day follow up visit. The dog died from a sudden attack of acute respiratory distress. Diagnosis: Numerous A. vasorum adults in the right ventricle and pulmonary artery and one adult in the anterior chamber detected at post-mortem examination.

Control of Canine Genetic Diseases. Padgett, G.A., Howell Book House 1998, pp. 198-199, 239.

Ocular Disorders Presumed to be Inherited in Purebred Dogs. Genetics Committee, A.C.V.O. 1999.

Guide to Congenital and Heritable Disorders in Dogs. Dodds WJ, Hall S, Inks K, A.V.A.R., Jan 2004, Section II(88).

Breed Predispositions to Disease in Dogs & Cats. Alex Gough, Alison Thomas. 2004; Blackwell Publ. 44-45.

Angiostrongylus vasorum at a pre-adult phase in the anterior chamber of a young dog’s eye. D. Payne. Munich: International Veterinary Ophthalmology Meeting. 2004;pg.125. Age and breed: 8-month-old Cavalier King Charles Spaniel. Location: France. Clinical presentation: Cough, uveitis, and presence of a motile worm in the anterior chamber of the eye. Diagnosis: Faecal and broncho-alveolar washing examination negative for A. vasorum larvae. One immature A. vasorum female extracted from the eye. Anthelmintic treatment: Fenbendazole-based treatment for 2 weeks.

Incidence of Canine Glaucoma with Goniodysplasia in Japan: A Retrospective Study. Kumiko Kato, Nobuo Sasaki, Satoru Matsunaga, Ryohei Nishimura, Hiroyuki Ogawa. J. Vet. Med. Sci. August 2006;68(8):853-858. Quote: The incidence of primary and secondary glaucoma in dogs was investigated. A total of 1244 dogs received ophthalmologic examinations, including tonometry and gonioscopy. Goniophotographs were taken using a goniolens to evaluate the iridocorneal angle (ICA) as well as pectinate ligament (PL). The anterior width of the ciliary cleft and the total distance from the origin of the PL to the anterior corneal surface were measured from the goniophotographs. Glaucoma was diagnosed based on the cupping of the optic nerve head, clinical signs, ocular changes, and high IOP, and it was synchronized with gonioscopic grades to differentiate between primary and secondary glaucoma. We investigated 1244 dogs of 29 breeds, including the mixed breed; among these, glaucoma was diagnosed in 127 dogs (162 eyes) [including two cavalier King Charles spaniels]. Of 162 eyes, primary glaucoma was diagnosed in 129 eyes and secondary glaucoma in 33 eyes. Shiba Inu dogs (42 dogs, 33%) showed the highest incidence of glaucoma, followed by Shih-Tzu (21 dogs, 16.5%). Furthermore, all the glaucomatous Shiba Inu dogs had primary glaucoma with abnormal ICA grades and dysplastic PLs. The findings of our study reveal that the Shiba Inu breed in Japan may have a hereditary predisposition to glaucoma.

Ophthalmic Disease in Veterinary Medicine. Charles L. Martin. Manson Publ. 2009; page 475, table 15.1. Quote: "Presumed Inherited Ocular Diseases: Table 15.1: Breed predisposition to eye disease in dogs: Cavalier King Charles Spaniel: ... ."

Breed Predispositions to Disease in Dogs & Cats (2d Ed.). Alex Gough, Alison Thomas. 2010; Blackwell Publ. 53.

Ocular conditions affecting the brachycephalic breeds. Peter G.C. Bedford. 2010. RVC. Quote: "There are two types of disease which affect the eye of the brachycephalic breeds and both are directly or indirectly related to genetic predisposition. First and by far the commonest are those conditions which are due to be conformation of skull and are related to the exophthalmos which is the common feature of these breeds. Second there are those conditions which have been unwittingly bred into some brachycephalic breeds in the pursuit of desired breed characteristics. In this lecture I will present an overview of all the diseases that the small animal practitioner is likely to encounter in the brachycephalic breeds of pedigree dog. The fourteen breeds I have included for discussion are the Affenpinscher, Boston Terrier, Boxer, Bulldog, Cavalier King Charles and the King Charles Spaniels, (mesaticephalic) French Bulldog, Griffon Bruxellois, Japanese Chin, Lhasa Apso, Pekingese, Pug, Shih Tzu and Tibetan Spaniel. ... Corneal Lipid Dystrophy: The term applies to the characteristic cholesterol and triglyceride deposits in the superficial corneal stroma seen most commonly in the Cavalier King Charles Spaniel. It is clinically benign and seldom affects vision to any noticeable degree. ... Hereditary Cataract: Hereditary cataract is seen in the Boston Terrier and the Cavalier King Charles Spaniel. ... Microphthalmos (MoD): Again the American literature suggests that microphthalmos (MoD) may be inherited in the Cavalier King Charles Spaniel."

Epidemiology of canine glaucoma presented to University of Zurich from 1995 to 2009. Part 2: secondary glaucoma (217 cases). Ann Refstrup Strom, Michael Hässig, Tine M. Iburg, Bernhard M. Spiess. Vet. Ophth. March 2011;14(2):127-132. Quote: Objective: To investigate the epidemiology of canine secondary glaucomas in the cases presented to the University of Zurich, Vetsuisse Faculty (UZH) from 1995 to 2009 focusing on possible risk factors for developing secondary glaucoma in this population of dogs. Methods: Information was obtained from the computer database of patients examined by members of the UZH Ophthalmology Service, between January 1995 and August 2009. Secondary glaucoma was diagnosed based on the presence of antecedent eye conditions. The data was evaluated for breed, gender, age at presentation, and for antecedent eye conditions known to cause glaucoma including anterior uveitis of unknown cause (AU), lens luxation (LL), intraocular surgery (SX), intraocular neoplasia (IN), unspecified trauma to the globe (T), ocular melanosis (OM), hypermature cataract (PY), hyphema (HY), and six other less frequent conditions. Results: A total of 217 dogs were diagnosed with secondary glaucoma from 1995 to 2009. The age of the dogs with secondary glaucoma ranged between 88 days and 19 years (mean 7.7 ± 3.6 years). Data suggested a predisposition for secondary glaucoma in the Cairn Terrier and the Jack Russell Terrier breeds from 2004 to 2009. Common causes of secondary glaucoma from 1995 to 2009 were AU (23.0%), LL (22.6%), SX (13.4%), IN (10.6%), T (8.3%), OM and PY (both 6.9%) and HY (3.23%). Conclusion: The report presents the epidemiology of secondary glaucomas presented to UZH from 1995 to 2009. ... The proportion of the Cairn Terriers, Jack Russell Terriers, Cocker Spaniels, Cavalier King Charles Spaniels, and Manchester Terriers in SEC0409 [secondary glaucoma group] were all overrepresented compared with the proportion of the same breeds in GAO409 [all the dogs presented to the hospital]. [Of 72 CKCSs presented to the hospital, 2 were diagnosed with secondary glaucoma.] ... Fourteen risk factors were recorded for secondary glaucoma. This is the first paper documenting OM in the Swiss Cairn Terrier dog population.

Ocular Disorders Presumed to be inherited in purebred dogs. Genetics Committee of the American College of Veterinary Ophthalmologists. Blue Book 6th Ed. 2013. pp. 241-247.

Blindness: A Step-by-Step Approach to Diagnosis. Alison Clode. NAVC Clinician's Brief. April 2014;14-15.

The genetics of eye disorders in the dog. Cathryn S. Mellersh. Canine Genetics & Epidemiology. April 2014. Quote: "Inherited forms of eye disease are arguably the best described and best characterized of all inherited diseases in the dog, at both the clinical and molecular level and at the time of writing 29 different mutations have been documented in the scientific literature that are associated with an inherited ocular disorder in the dog. The dog has already played an important role in the identification of genes that are important for ocular development and function as well as emerging therapies for inherited blindness in humans. Similarities in disease phenotype and eye structure and function between dog and man, together with the increasingly sophisticated genetic tools that are available for the dog, mean that the dog is likely to play an ever increasing role in both our understanding of the normal functioning of the eye and in our ability to treat inherited eye disorders. This review summarises the mutations that have been associated with inherited eye disorders in the dog."

Keratomycosis in five dogs. Jessica C. Nevile, Simon D. Hurn, Andrew G. Turner. Vet. Ophthalmology. September 2015. Quote: "Five cases of canine keratomycosis were diagnosed and treated at a private Veterinary Ophthalmology Practice in Melbourne, Australia. Clinical presentations varied between dogs. Predisposing factors were identified in 4 of 5 cases. Diagnostic modalities utilized were corneal cytology and fungal culture. ... Case 1. A 10-year 7-month-old spayed female Cavalier King Charles Spaniel was referred for a corneal ulcer in the right eye (OD). The dog was systemically healthy, there was no known history of trauma, and the dog had not been treated with topical or systemic corticosteroids prior to presentation. ... Corneal cytology confirmed the presence of fungal organisms in all five cases. Aspergillus, Scedosporium, and Candida were cultured from three cases, respectively. Specific antifungal treatment included 1% voriconazole solution or 1% itraconazole ointment. Keratectomy and conjunctival grafting surgery was performed in two patients. Resolution of infection and preservation of vision were achieved in 4 of 5 patients."

Angiostrongylus vasorum in the eye: new case reports and a review of the literature. Vito Colella, Riccardo Paolo Lia, Johana Premont, Paul Gilmore, Mario Cervone, Maria Stefania Latrofa, Nunzio D’Anna, Diana Williams, Domenico Otranto. BioMed Central. March 2016. Quote: "Background: Nematodes of the genus Angiostrongylus are important causes of potentially life-threatening diseases in several animal species and humans. Angiostrongylus vasorum affects the right ventricle of the heart and the pulmonary arteries in dogs, red foxes and other carnivores. The diagnosis of canine angiostrongylosis may be challenging due to the wide spectrum of clinical signs. Ocular manifestations have been seldom reported but have serious implications for patients. Methods: The clinical history of three cases of infection with A. vasorum in dogs diagnosed in UK, France and Italy, was obtained from clinical records provided by the veterinary surgeons along with information on the diagnostic procedures and treatment. Nematodes collected from the eyes of infected dogs were morphologically identified to the species level and molecularly analysed by the amplification of the nuclear 18S rRNA gene. Results: On admission, the dogs were presented with various degrees of ocular discomfort and hyphema because of the presence of a motile object in the eye. The three patients had ocular surgery during which nematodes were removed and subsequently morphologically and molecularly identified as two adult males and one female of A. vasorum. ... Angiostrongylus vasorum in the eye of CKCSCase 2: A 2-year-old male Cavalier King Charles Spaniel dog was referred to a private veterinary clinic in Paris (France) due to persistent blepharospasm and epiphora. The dog that lived in the city centre was walked in a forest nearby. On clinical ophthalmological examination the dog showed prolapse of the nictitating membrane, photophobia on the left eye, iris hyperaemia and corneal oedema. The intraocular pressure was 14 mmHg in the left eye and 16 mmHg in the right eye, the fluorescein test was negative and the Schirmer test showed a slightly increased lacrymation. A thread-like organism was noticed in the anterior chamber of the left eye (photo at right), which was very motile under light stimuli. ... Removal of the parasite was performed by anterior chamber paracentesis and the nematode was morphologically and molecularly processed. The specimen was identified as an unfertilised A. vasorum female. Briefly, the female nematode measured 16 mm in length and 0.2 mm in width; genital ducts were coiled around the reddish intestine, which appeared visible throughout the cuticle. However, the nematode was damaged and further morphological features were not evaluated, with the exception of the uteri, which lacked first-stage larvae, and the vulva. Therefore, the dog was subjected to coprological examination for the detection of L1 using the Baermann technique. The 18S rDNA sequences obtained from both L1 collected from the faeces and the female nematode displayed 100 % identity to the nucleotide sequence of A. vasorum [GenBank: AJ920365]. The dog lacked any signs of respiratory infection, both previously and during the observation period. The animal was treated with fenbendazol 25 mg/Kg per os SID for 3 weeks associated with prednisolone 0.2 mg/Kg. ... Conclusions: Three new cases of canine ocular angiostrongylosis are reported along with a review of other published clinical cases to improve the diagnosis and provide clinical recommendation for this parasitic condition. In addition, the significance of migratory patterns of larvae inside the host body is discussed. Veterinary healthcare workers should include canine angiostrongylosis in the differential diagnosis of ocular diseases. ... Interestingly, all dogs suffering from canine ocular angiostrongylosis were under the 3 years of age (i.e. 5 months to 3 years), and of the few reports now available in literature, three and in Case 2, involved Cavalier King Charles Spaniel dogs. However, additional epidemiological data are needed for a clear assessment of risk factors (e.g. breed and age) related to the occurrence of canine ocular angiostrongylosis."

Infectious crystalline keratopathy in dogs and cats: clinical, in vivo confocal microscopic, histopathologic, and microbiologic features of eight cases. Eric C. Ledbetter, Patrick L. McDonough, Kay Kim. Veterinary Ophthalmology. June 2016. Quote: Objective: To describe clinical, in vivo confocal microscopic, histopathologic, and microbiologic features of canine and feline cases of infectious crystalline keratopathy (ICK). Animals studied: Six dogs [including one cavalier King Charles spaniel] and two cats with naturally acquired ICK. Procedures: Medical records of dogs and cats with a clinical diagnosis of ICK were reviewed. Signalment, medical history, clinical findings, and diagnostic evaluations were retrieved, including corneal cytology, histopathology, in vivo confocal microscopy, and microbiology results. Results: All animals presented with fine, needle-like, and branching white crystalline anterior stromal opacities emanating from corneal facets or corneal epithelial defects. Mild conjunctival hyperemia and anterior uveitis were frequently present. Concurrent ocular and systemic diseases were common, including keratoconjunctivitis sicca, corneal sequestrum, diabetes mellitus, hyperadrenocorticism, and malignant neoplasia. Bacteria, with minimal or absent leukocytes, were identified by cytology and histopathology. Histopathologically, the crystalline corneal opacities corresponded with dense accumulations of bacteria present in the interlamellar stromal spaces and forming cord-like projections within the stroma. In vivo confocal microscopy demonstrated deposits of reflective crystalline or amorphous structures within the stroma with a paucity of associated inflammatory changes. The most frequently cultured bacteria were alpha-hemolytic Streptococcus and Staphylococcus species. Resolution of clinical lesions was achieved in most cases with long-term medical or surgical therapy; however, the initiation of medical treatment was associated with an acute, dramatic onset of severe keratitis and anterior uveitis in some animals. Conclusions: Infectious crystalline keratopathy in dogs and cats shares many features with this condition in human patients. Prolonged medical therapy, or surgical intervention, is required for resolution.

Eye blink rate, tear production, and corneal sensitivity in cavalier king charles spaniels. GV Fontinhas Netto, AR Eyherabide, AP Ribeiro, AA Bolzan. Vet. Ophthal. November 2016;19(6):E25#29. Quote: Purpose: To determine the eye blink rate, tear production and corneal sensitivity in the Cavalier King Charles Spaniels. Methods: Eleven healthy Cavalier King Charles Spaniels (5 females and 6 males) aged from 3 to 10 years were included in this study. These dogs were from the “Lilies Cavaliers Kennel” (Valinhos, Sao Paulo, Brazil) and all procedures were conducted with the consent of the owner. The eye blink rate (EBR) was obtained from digital video imaging of each dog’s eyes captured during three minutes and represented a counting of the eyelid movements (complete and incomplete blinks). Tear production was measured with the Schirmer tear test 1 (STT1). The central corneal sensitivity was determined by evaluating the corneal touch threshold (CTT) with the Cochet-Bonnet aesthesiometer. The tests were performed in both eyes without instillation of anesthetic eye drops. The right eye was the first eye tested. Results: There were no significant differences between the left and right eyes (P ≤ 0.05). The mean value of the EBR was 9.6 blinks/minute (0.6 complete blinks and 9.0 incomplete blinks). Mean ± SD tear production was 24.1 ± 1.6 mm/minute and CTT was 1.7 ± 0.3 cm. Conclusions: The procedures were easy to perform and reliable to measure the chosen parameters. The values obtained in our study are original (except tear production) and may contribute to establish normal patterns for eye blink rate, tear production and corneal sensitivity in adult Cavalier King Charles Spaniels.

Ocular biometry by computed tomography in different dog breeds. Carolin L. H. Chiwitt, Stephen J. Baines, Paul Mahoney, Andrew Tanner, Christine L. Heinrich, Michael Rhodes, Heidi J. Featherstone. Vet. Ophth. November 2016. Quote: Objective: To (i) correlate B-mode ocular ultrasound (US) and computed tomography (CT) (prospective pilot study), (ii) establish a reliable method to measure the normal canine eye using CT, (iii) establish a reference guide for some dog breeds, (iv) compare eye size between different breeds and breed groups, and (v) investigate the correlation between eye dimensions and body weight, gender, and skull type (retrospective study). Procedure: B-mode US and CT were performed on ten sheep cadaveric eyes. CT biometry involved 100 adult pure-bred dogs with nonocular and nonorbital disease, representing eleven breeds [including ten cavalier King Charles spaniels]. Eye length, width, and height were each measured in two of three planes (horizontal, sagittal, and equatorial). Results: B-mode US and CT measurements of sheep cadaveric eyes correlated well (0.70–0.71). The shape of the canine eye was found to be akin to an oblate spheroid (a flattened sphere). A reference guide was established for eleven breeds. Eyes of large breed dogs (GSD, Labrador Retriever, Boxer) were significantly larger than those of medium ((Border Collie, SBT, Cocker Spaniel, ESS) and small breed dogs (CKCS, Border Terrier, JRT, WHWT) (P < 0.01), and eyes of medium breed dogs were significantly larger than those of small breed dogs (P < 0.01). ... There was no significant difference between the CKCS eye (a small breed) and the medium breed group. ... Eye size correlated with body weight (0.74–0.82) but not gender or skull type. Conclusions: Computed tomography is a suitable method for biometry of the canine eye, and a reference guide was established for eleven breeds. Eye size correlated with breed size and body weight. ... The CKCS had a relatively large eye for the small breed group. ... Because correlation between B-mode US and CT was shown, the obtained values can be applied in the clinical setting, for example, for the diagnosis of microphthalmos and buphthalmos.Ocular Biometry

Use of a 350-mm2 Baerveldt glaucoma drainage device to maintain vision and control intraocular pressure in dogs with glaucoma: a retrospective study (2013–2016). Kathleen L. Graham, David Donaldson, Francis A. Billson, F. Mark Billson. Vet. Ophth. November 2016. Quote: Objective: To evaluate the 350-mm2 Baerveldt glaucoma drainage device (GDD) in dogs with refractory glaucoma when modifications to address postoperative hypotony (extraluminal ligature; intraluminal stent) and the fibroproliferative response (intraoperative Mitomycin-C; postoperative oral colchicine and prednisolone) are implemented as reported in human ophthalmology. Design: Retrospective case series. Animals: Twenty-eight client-owned dogs [including a cavalier King Charles spaniel] (32 eyes) including seven dogs (nine eyes) with primary glaucoma and 21 dogs (23 eyes) with secondary glaucoma. Methods: The medical records of all dogs undergoing placement of a 350-mm2 Baerveldt GDD at a veterinary ophthalmology referral service between 2013 and 2016 were reviewed. Signalment, diagnosis, duration and previous treatment of glaucoma, previous intraocular surgery, IOP, visual, and surgical outcomes were recorded. Results: IOP was maintained <20mmHg in 24 of 32 (75.0%) eyes. Fourteen eyes (43.8%) required no adjunctive treatments to maintain this IOP control. Fewer doses of glaucoma medication were required following surgery. Vision was retained in 18 of 27 (66.7%) eyes with vision at the time of surgery. No eyes that were blind at the time of surgery (n = 5) had restoration of functional vision. Complications following surgery included hypotony (26/32; 81.3%), intraocular hypertension (24/32; 75.0%), and fibrin formation within the anterior chamber (20/32; 62.5%). The average follow-up after placement of the GDD was 361.1 days (median 395.6 days). Conclusion: Efforts to minimize postoperative hypotony and address the fibroproliferative response following placement of a 350-mm2 Baerveldt GDD showed an increased success rate to other reports of this device in dogs and offers an alternative surgical treatment for controlling intraocular pressure in dogs with glaucoma.

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