Our staff in print.
Many of our staff members contribute to our Newsletter and the DVS online Magazine as well as other professional publications. Much of this material is intended for veterinary professionals however, there are Fact Sheets available for our general readership (including pet owners) here at our website.

Polydipsia, defined as a water intake of over 100 ml/kg/day, is a common presenting medical complaint in dogs. Polydipsia can be secondary (eg, to central or nephrogenic diabetes insipidus) or primary in origin, where increased water intake cannot be explained as a response to obligatory water loss. Primary polydipsia is confirmed by ruling out other known causes of polydipsia and demonstrating that renal concentrating ability is intact.

The causes and associations of primary polydipsia in dogs are poorly defined. This report describes three dogs presented with signs of gastrointestinal disease with concurrent polydipsia. Investigations (including water deprivation testing) showed normal renal urinary concentrating ability and indicated primary polydipsia. Treatment of the gastrointestinal signs resulted in resolution of the polydipsia in each case. This is the first description of a possible association between gastrointestinal disease and primary polydipsia in the dog, the pathophysiology of which remains obscure.

Gastrointestinal/Primary polydipsia association

Ambulatory electrocardiography techniques are superior to standard electrocardiography in evaluating rhythm disturbances in dogs with episodic weakness or collapse. Disadvantages include cumbersome equipment, short recording periods and an inherent delay in trace analysis. A small programmable cardiac event recorder with combined automatic and owner-triggered recording capability was evaluated in 13 healthy dogs in a hospital environment. The unit was well tolerated and produced diagnostic recordings directly to a personal computer, with useful information about continuous heart rate. It detects premature complexes, pauses and bradycardias according to programmed detection thresholds.

These events were counted frequently but trace review revealed concerns regarding specificity. Recordings were often triggered by sinus arrhythmia, sinus tachycardia and unclassifiable rate changes rather than by clinically significant arrhythmias. Correct detection of ventricular ectopic complexes, a single supraventricular premature complex, sinus arrest and second-degree atrioventricular block occurred in individual dogs. Visual review of all automatically recorded events was essential and significantly increased the time required for event recording analysis. Manual recordings might be more useful and the overall results suggest that further studies are warranted to evaluate the system in clinical cases in the home environment.

ECG event recorder

A 13-year-old, crossbreed dog presented with a history of recent onset polydipsia, progressive lethargy, weakness and reduced appetite. Blood tests showed raised concentrations of alkaline phosphatase and alanine aminotransferase with marginally low serum potassium. There was a leucocytosis with a mature neutrophilia and no eosinophils. Endocrine tests showed a normal aldosterone concentration and an exaggerated adrenocorticotropic hormone (ACTH) stimulation test, consistent with a diagnosis of hyperadrenocorticism (HAC).

A diagnosis of adrenal-dependent HAC was made, based on the presence of a calcified mass involving the left adrenal gland, and hepatomegaly, on radiography and ultrasonography. The owners declined surgical adrenalectomy. Medical management with trilostane rapidly improved the clinical signs and normalised the serum chemistry. ACTH stimulation tests showed an improvement in post-ACTH cortisol concentrations and were used to make dose adjustments where necessary. At the time of writing, no adverse side effects had been seen and the dog remained well after 80 weeks of treatment.

Trilostane treatment, adrenocortical neoplasia

The case records of 36 cats and dogs undergoing surgical correction of a single extrahepatic portosystemic shunt were reviewed. In 12 animals, the shunt was fully ligated during the first surgical procedure, while, in the remaining 24, the shunting vessel could only be partially ligated. Assessment of serum bile acid concentrations demonstrated complete shunt occlusion in 15 of these latter 24 animals (63 per cent) between one and six months postoperatively.

Ten animals (28 per cent) had persistently high serum bile acid concentrations postoperatively. Portovenogram findings in these individuals revealed six that demonstrated shunting solely through the original vessel; In five of these, full shunt attenuation was achieved at second surgery. Further shunt manipulation was not possible in the sixth case due to extensive adhesion formation. In the remaining four animals with raised bile acid concentrations, the portovenogram demonstrated shunting through the original vessel as well as the development of multiple acquired shunts.