Abstract:
A 6-month-old female Staffordshire bull terrier cross presented to the Onderstepoort
Veterinary Academic Hospital with lethargy, weakness, decreased appetite, abnormal
vocalisation, twitching of the facial muscles and ears, circling, alopecia, pruritus, seborrhoea
sicca and erythema. Serum biochemistry revealed severe hypernatraemia (200.4 mmol/L;
Reference Interval 140 mmol/L – 155 mmol/L). Treatment required careful administration
of intravenous fluids. The electrolytes were monitored to ensure slow and controlled sodium
normalisation (the target reduction of Na concentration was by 0.5 mmol/L/h – 1 mmol/L/h
or 12 mmol/L/24 h – 24 mmol/L/24 h). Despite the careful fluid calculations and close
monitoring, the serum sodium levels dropped more than the recommended 0.5 mmol/L/h –
1 mmol/L/h in the first 4 h and the fluids had to be adjusted. The patient’s habitus improved
and the central nervous system signs started to resolve after 1 day of fluid treatment. The
puppy started eating food mixed with water, but made no attempt to drink water. The
pruritus and erythema resolved once the sodium levels normalised and the seborrhoea sicca
began to resolve. At a follow up visit 20 days post discharge the skin was normal. A diagnosis
of hypernatraemia as a result of pure water loss due to hypodipsia or adipsia was made, as
the puppy made no attempt to drink water when her serum sodium levels increased (a strong
thirst stimulus). Hypernatraemia recurred if she was not forced to take in adequate amounts
of water mixed with her food. Dermatological changes such as seborrhoea, hyperkeratosis and
alopecia have been reported in a few other cases of hypernatraemia in dogs and sodium levels
should be investigated in dermatological patients when no other cause can be established. This
study, supported by another retrospective study done in 2008, suggests that the Staffordshire
bull terrier may be a breed that is predisposed to hypernatraemia.
