Sylvia C. Djajadiningrat-Laanen

Primary hyperaldosteronism: Expanding the diagnostic net

Practical relevance Primary hyperaldosteronism is probably the most common adrenocortical disorder in cats. As in humans, it is often unrecognised, which excludes a potentially large number of cats from appropriate treatment. Patient group Affected cats present at a median age of 13 years (range 5–20 years). A breed or sex predilection has not been documented. The excessive secretion of mineralocorticoids usually leads to hypokalaemia and/or systemic arterial hypertension. Most affected cats present with muscular weakness and/or ocular signs of arterial hypertension. Diagnostics In any cat presenting with hypokalaemia and/or arterial hypertension, other potential causes should be excluded. The ratio of plasma aldosterone concentration to plasma renin activity (aldosterone:renin ratio) is currently the best screening test for feline primary hyperaldosteronism. Diagnostic imaging is required to differentiate between adrenocortical neoplasia and bilateral hyperplasia, and to detect any distant metastases. Clinical challenges The differentiation between adrenocortical neoplasia and bilateral hyperplasia is imperative for planning optimal therapy, but the limited sensitivity of diagnostic imaging may occasionally pose a problem. For confirmed unilateral primary hyperaldosteronism, unilateral adrenalectomy is the treatment of choice, and offers an excellent prognosis, but potentially fatal intra- and postoperative haemorrhage is a reported complication and risk factors have yet to be identified. Evidence base Only a few case reports are available on which to base the optimal diagnostic and therapeutic approach to feline primary hyperaldosteronism. This article reviews the physiology of aldosterone production and the pathophysiology of primary hyperaldosteronism, and summarises the currently available literature on the feline disease. Practical suggestions are given for the diagnostic investigation of cats with suspected primary hyperaldosteronism.

Urinary aldosterone to creatinine ratio in cats before and after suppression with salt or fludrocortisone acetate.

BACKGROUND The endocrine diagnosis of primary hyperaldosteronism in cats currently is based on an increased plasma aldosterone to renin ratio, which has several disadvantages for use in veterinary practice. OBJECTIVES To establish a reference range for the urinary aldosterone to creatinine ratio (UACR) and to determine whether oral administration of either sodium chloride or fludrocortisone acetate is effective for use in a suppression test. ANIMALS Forty-two healthy cats from an animal shelter and 1 cat with primary hyperaldosteronism from a veterinary teaching hospital. METHODS Morning urine samples for determination of the basal UACR were collected from 42 healthy cats. For the suppression tests, urine samples for the UACR were collected after twice daily oral administration for 4 consecutive days of either sodium chloride, 0.25 g/kg body weight (n = 22) or fludrocortisone acetate, 0.05 mg/kg body weight (n = 15). RESULTS The median basal UACR was 7.2 x 10(-9) (range, 1.8-52.3 x 10(-9)), with a calculated reference range of < 46.5 x 10(-9). Administration of sodium chloride resulted in adequate salt loading in 10 of 22 cats, but without significant reduction in the UACR. Administration of fludrocortisone resulted in a significant decrease in the UACR (median, 78%; range, 44-97%; P < .001) in healthy cats. In the cat with an aldosterone-producing adrenocortical carcinoma, the basal UACR and the UACR after fludrocortisone administration were 32 x 10(-9) and 36 x 10(-9), respectively. CONCLUSIONS AND CLINICAL IMPORTANCE Using the UACR for an oral fludrocortisone suppression test may be useful for the diagnosis of primary hyperaldosteronism in cats.

Characterization and prevalence of cataracts in Labrador Retrievers in The Netherlands.

OBJECTIVE To assess the prevalence and distribution of types of cataract, investigate the effects of selective breeding on cataract development, and identify the relationship between posterior polar cataract and other types of cortical cataracts in Labrador Retrievers in The Netherlands. ANIMALS 9,017 Labrador Retrievers. PROCEDURES Records of 18,283 ophthalmic examinations performed by veterinary ophthalmologists from 1977 through 2005 were reviewed. There were 522 dogs affected by hereditary cataracts in 1 or both eyes without progressive retinal atrophy (PRA) and 166 PRA-affected dogs with cataracts. These cataracts were divided into 3 groups: posterior polar (triangular) cataract, extensive immature and mature cataract, and a miscellaneous group. Dogs with PRA were analyzed separately. RESULTS From 1980 through 2000, the prevalence of hereditary cataracts was stable at 8%. The prevalence of cataracts in offspring of cataract-affected dogs was significantly increased, compared with the prevalence in offspring of nonaffected dogs. The distribution of types of cataract was significantly different between dogs with primary cataracts and PRA-affected dogs. Dogs with posterior polar (triangular) cataracts produced affected offspring with the same distribution of types of cataracts as the entire population of primary cataract-affected dogs. CONCLUSIONS AND CLINICAL RELEVANCE Cataract development in the Labrador Retriever population in The Netherlands appears to be a predominantly genetic disorder. Posterior polar (triangular) cataracts appear to be related to other types of hereditary cataract. Although there is no conclusive evidence, it seems valid to continue exclusion of all Labrador Retrievers affected by any type of primary cataract from breeding.

Use of bandage contact lenses for treatment of spontaneous chronic corneal epithelial defects in dogs.

OBJECTIVE To determine whether polyxylon bandage contact lenses influence healing time and ocular comfort in the management of spontaneous chronic corneal epithelial defects in dogs. METHODS Twenty dogs with spontaneous chronic corneal epithelial defects were included. All dogs were treated by debridement under topical anaesthesia at the first presentation. Ten dogs were assigned to the study group (application of a polyxylon bandage contact lens), and the remaining ten served as a control group. The healing time and ocular (dis)comfort were evaluated by assessment of the clinical findings and an owner-based questionnaire. All dogs received the same topical and systemic medication. RESULTS Healing time for dogs in the study population was significantly shorter (mean 14±0 days) than for dogs in the control group (mean 36±17 days; P=0·005). The spontaneous chronic corneal epithelial defects had completely healed at the first recheck in all dogs with a polyxylon bandage contact lens. The duration of blepharospasm following debridement was significantly shorter in the study population (mean 4±4 days) than in the control group (mean 30±20 days; P=0·001). CLINICAL SIGNIFICANCE The use of polyxylon bandage contact lenses is beneficial in the management of spontaneous chronic corneal epithelial defects.

Peri- and retrobulbar abscess caused by chronic otitis externa, media and interna in a dog

OTITIS externa is a common disease in dogs, and Proteus and Pseudomonas species are frequently cultured from chronic cases ([Welch Fossum 2002][1], [Krahwinkel 2003][2]). Otitis media in dogs is usually preceded by a bacterial infection of the external ear canal. The signs of otitis media, such as a

Development of tear production and intraocular pressure in healthy canine neonates

OBJECTIVE The aim of this study was to investigate the development of aqueous tear production and intraocular pressure in healthy canine neonates between 2 and 12 weeks of age. ANIMALS One litter, consisting of 8 healthy Beagle dogs--four males and four females-was used. PROCEDURES Between the age of 2 and 12 weeks, tear production and intraocular pressure were measured weekly in both eyes. Tear production was measured by Schirmer tear test, before (STT1) and after (STT2) topical anesthesia and drying of the conjunctival sac. Intraocular pressure (IOP) was measured using a rebound tonometer. As no significant differences existed between left and right eye measurements (STT1, STT2, and IOP) at all time points, only right eye measurements were further analyzed. RESULTS STT1, STT2, and IOP values increased significantly until the age of 9 weeks for STT1, until the age of 10 weeks for STT2, and until the age of 6 weeks and again between 10 and 11 weeks of age for IOP. IOP decreased significantly between 11 and 12 weeks of age. There were no significant differences in STT1, STT2, and IOP between males and females, except for IOP at 10 and 12 weeks of age. No significant correlation was demonstrated between body weight and STT1 or STT2. CONCLUSIONS STT1, STT2, and IOP values increased significantly in the first weeks after birth. The results of this study indicate that separate reference values for tear production and intraocular pressure need to be established for neonatal dogs.

Distichiasis in a ferret (Mustela putorius furo)

A 4-year-old intact male ferret was presented to the Ophthalmology Service of the Department of Clinical Sciences of Companion Animals of Utrecht University with chronic blepharospasm, epiphora, and conjunctivitis of the right eye. Examination of the eye revealed mild conjunctivitis and three hairs protruding from the openings of meibomian glands in the upper eyelid, providing the clinical diagnosis of distichiasis. The distichia were removed by transconjunctival unipolar electrocautery. Recovery was uneventful, but the original signs recurred 10 weeks after surgery. Ophthalmic examination revealed another distichia at a different location in the same eyelid and it was removed by full-thickness wedge excision. Histopathological examination failed to reveal the exact origin of the distichia. To our knowledge, this is the first reported case of distichiasis in a ferret.