University:
University of Edinburgh
Course:
BILG08011 | Animal Biology 2
Academic year:

2023
Views:

412

Pages:

2
Author:

cissoulzlv

INTERNAL MEDICINE CASE STUDIES Primary adipsia in 7 month old entire female Staffordshire Bull Terrier A 7 month old entire female Staffordshire Bull Terrier was referred to the R(D)SVS Internal Medicine Service with a 2 week history of depression, anorexia, hindlimb weakness and collapse. The owner reported that she had never seen the dog drink water. On clinical examination, the dog was depressed and recumbent. Serum biochemistry revealed marked increases in serum sodium and chloride concentrations (table 1). Urine specific gravity was 1.030. The finding of marked hypernatraemia and concentrated urine in a dog with a history of adipsia was highly suggestive of primary adipsia. The dog was treated with intravenous fluids with the aim of slowly correcting the hypernatraemia. In this case it was likely that the hypernatraemic state had developed over many weeks and a rapid reduction of plasma osmolality could result in an intracellular influx of water into neurons resulting in further neurological dysfunction. Over the following five days the dog’s serum sodium concentration were slowly lowered and the dog’s demeanour and appetite improved. The dog was discharged with instructions to add the dog’s daily water requirement to the dog’s low sodium diet. At a recheck two weeks after discharge, her owner reported that the dog was very lively and exercising normally. Serum sodium and chloride concentrations were marginally above the reference range (table 1). Under normal physiological conditions, the presence of hyperosmolality induces the release of arginine vasopressin and stimulates thirst receptors in the hypothalamus. Despite marked increases in plasma osmolality and sodium, these mechanisms fail to stimulate adipsic dogs to drink water. There have only been a handful of cases of primary adipsia reported in dogs and tend to occur in dogs with brain malformations and inflammatory brain disorders which may impair hypothalamic osmoreceptor function1. In this case, the adipsic condition had been present from birth and advanced brain imaging, ideally MRI, would have been required to further evaluate the brain for any structural abnormalities. In terms of management of hypernatraemia associated with primary adipsia, the key requirement is to slowly reduce serum sodium concentrations and to closely monitor electrolytes during hospitalisation. In the absence of a significant primary CNS pathology, the long term prognosis for primary adipsia is reasonably good. . page 1 of 2 Sodium (mmol/l) Potassium (mmol/l) Chloride (mmol/l) Day 1 196 * 3.9 143 * Day 2 186 * 3.9 136 * Day 3 168 * 4.0 125 * Day 4 147 4.1 112 Day 5 135 4.5 101 Day 20 156 * 5.0 118 * Reference range 139-154 3.6-5.6 99-115 Table 1 : Serum electrolyte concentrations * above reference range, ** below reference range References 1 Jeffery et al (2003) Brain malformations associated with primary adipsia identified using magnetic resonance imaging. Veterinary Record. 152, 436-38 The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. www.ed.ac.uk/vet/hfsa-int-med page 2 of 2