F.J. van Sluijs

Gauged attenuation of congenital portosystemic shunts: results in 160 dogs and 15 cats.

Summary Portosystemic shunts were ligated over a gauged stainless steel rod in 160 dogs and 15 cats, using a midline celiotomy. The diameter of the rod varied with the size of the shunt and the diameter of the portal vein cranial to the shunt. Shunts were narrowed to the smallest diameter that did not cause signs of portal hypertension such as cyanosis of the stomach, pancreas, and small intestine. A slight discoloration was accepted only if the heart rate, end‐expiratory CO2%, or arterial blood pressure (if available) did not deviate more than 15% from the values that were recorded at the beginning of the surgical procedure. The perioperative mortality (0–30 days) was 29%. The most common cause of death was euthanasia because of hypoplasia of the portal vein cranial to the shunt. Animals with intrahepatic shunts had a significantly lower probability of survival than animals with extrahepatic portocaval or portoazygos shunts. In dogs, large breed and a high body weight were also significant risk factors for non‐survival. Age had a significant effect on risk of non‐survival, with an increased risk for older dogs, irrespective of the breed of the dog (large breed vs. small breed). The probability of survival without recurrence of hepatoencephalopathy (HE) after 1 and 4 years was 61.3% and 55.7%, respectively. The only variable that was significantly associated with non‐recurrence of HE was the breed of the dog, there being a lower probability for large breeds. Among the animals that survived surgery for more than 30 days, there was a significant higher probability of recurrence of HE in cats than in dogs.

Results of adrenalectomy in 36 dogs with hyperadrenocorticism caused by adrenocortical tumour

A total of 38 adrenocortical tumours were removed from 36 dogs with hyperadrenocorticism. The surgical approach was by way of a unilateral flank laparotomy (32 dogs; 14 left and 18 right), a bilateral flank laparotomy (3 dogs) or a midline celiotomy (1 dog). Two dogs were euthanized during surgery because their tumours could not be resected. Eight dogs died from post-operative complications. Pancreatic necrosis with peritonitis was the most common cause of death. Eight of the 26 dogs that survived had signs of recurrence of hyperadrenocorticism. Unsuppressible hyperadrenocorticism was found in four dogs; one dog had probably pre-existent pituitary-dependent hyperadrenocorticism, and adrenocortical function could not be re-examined in the remaining three dogs. Among the 37 tumours examined microscopically expansion of neoplastic tissue into blood vessels was found in 22 of them. Four adrenal glands with adrenocortical tumours also contained phaeochromocytomas. Necropsy was performed in eight dogs. Metastases were found in the lungs of two dogs and in the lungs and liver in one dog. In combination with the data of previous reports, it is suggested that histological findings in surgery specimens are not good predictors for the clinical outcome.

Endocrinology: Hyperaldosteronism in a cat with metastasised adrenocortical tumour

Summary In a 12‐year‐old male shorthaired cat with attacks of hypo‐kalaemic muscular weakness in spite of oral potassium supplementation, highly elevated plasma aldosterone concentrations in combination with low plasma renin activity pointed to primary hyperaldosteronism. Ultrasonography and computed tomography revealed a large left‐sided adrenal tumour growing into the phrenicoabdominal vein and the caudal vena cava. The tumour and its intravascular extension were surgically removed, but the subsequent stenosis of the caudal vena cava caused congestion and renal failure. At autopsy pulmonary micrometastases of the aldosteronoma were found.

Small size of food particles and age as risk factors for gastric dilatation volvulus in great danes

A case-control study was conducted to investigate whether age, gender, neuter status, type of food, feeding frequency, food intake time, interval between feeding and exercise, duration of exercise and overall physical activity were risk factors for gastric dilatation volvulus (GDV) in the great dane. The sample population consisted of 38 great danes with acute GDV (cases) and 71 great danes owned by members of the Dutch Great Dane Association (controls). Information on the risk factors was collected by using clinical data in combination with a questionnaire, and the data were analysed by backward stepwise conditional logistic regression analysis. Dogs fed a diet containing particles of food >30 mm in size (kibble and/or dinner and/or home-prepared food with large pieces of meat) had a lower risk of GDV than dogs fed a diet containing only particles <30 mm in size (kibble or dinner and/or canned meat and/or home-prepared food cut into small pieces or ground in a food processor). Increasing age was also a risk factor for GDV. Gender, neuter status, feeding frequency, food intake time, the interval between feeding and exercise, the duration of exercise, and overall physical activity were not identified as risk factors. Feeding a diet including large pieces of meat may help to reduce the incidence of GDV in great danes.

Aldosteronoma in a dog with polyuria as the leading symptom

In a 10-year-old castrated male shorthaired German pointer polyuria was associated with slight hypokalemia, hypophosphatemia and alkalosis, as well as elevated plasma concentrations of a glucocorticoid-inducible iso-enzyme of alkaline phosphatase. Repeated measurements of urinary corticoids and normal suppressibility of the hypothalamus-pituitary-adrenocorticial axis excluded glucocorticoid excess. Urine osmolality (Uosm) did not increase during administration of the vasopressin analogue desmopressin. At the time water deprivation had caused Uosm to rise from 300 to 788 mOsm/kg, there was also plasma hypertonicity. During hypertonic saline infusion the osmotic threshold for vasopressin release was increased. The combination of elevated plasma aldosterone concentrations and unmeasurably low plasma renin activity pointed to primary hyperaldosteronism. As initially computed tomography (CT) did not reveal an adrenocortical lesion, the dog was treated with the aldosterone antagonist spironolactone. This caused Uosm to rise in a dose-dependent manner. However, well-concentrated urine was only achieved with doses that gave rise to adverse effects. Once repeated CT, using 2-mm-thick slices, had revealed a small nodule in the cranial pole of the left adrenal, unilateral adrenalectomy was performed which resolved the polyuria completely. Also the plasma concentrations of kalium, aldosterone and renin activity returned to within their respective reference ranges. The adrenocortical nodule had the histological characteristics of an aldosteronoma, with the non-affected zona glomerulosa being atrophic.In this dog with primary hyperaldosteronism the polyuria was characterized by vasopressin resistance and increased osmotic threshold of vasopressin release, similar to the polyuria of glucocorticoid excess. The possibility is discussed that the polyuria of glucocorticoid excess is actually a mineralocorticoid effect.

Perineal hernia repair in the dog by transposition of the internal obturator muscle. II. Complications and results in 100 patients.

A modified technique for transposition of the internal obturator muscle was used to repair perineal hernias in 100 dogs. Complications and long-term results are described. The most important complications were wound infection (45%), faecal incontinence (15%), and perineal fistula (7%). These complications often occurred in combination. The recurrence rate of perineal hernia was 5%. Nine of the 15 patients with faecal incontinence had paresis of the external anal sphincter or faecal incontinence before surgery. We suggest that in numerous patients, faecal incontinence is a complication of the condition rather than a complication of treatment. The owners assessment of the surgical result was good in 71% and moderate in 18% of the cases.

Quantitation of portosystemic shunting in dogs by ultrasound-guided injection of 99MTc-macroaggregates into a splenic vein

A technique is described for the ultrasound-guided injection of 99mTc-macroaggregates into a splenic vein in order to quantitate portosystemic collateral circulation. The fraction of portal blood by-passing the liver was derived from the radioactivity trapped in the liver and lungs and was expressed as the shunt index (SI). The method was tested in healthy dogs without shunting, and in dogs with single hereditary portosystemic shunts before and one month after surgical closure of the shunt. The mean SI was 0.01 (range 0.01 to 0.05) in healthy dogs and 0.94 (0.69 to 1.00) in dogs with hereditary shunts. After partial closure of the shunts the SI decreased to 0.25 (0.03 to 0.70). There was a significant positive correlation between the logarithms of the concentration of ammonia in plasma and the SI (r = 0.87, P < 0.001).

Persistent Mullerian duct syndrome in a Miniature Schnauzer dog with signs of feminization and a Sertoli cell tumour

A 5-year-old male Miniature Schnauzer was presented with unilateral cryptorchidism and signs of feminization. Abdominal ultrasonography revealed an enlarged right testis and a large, fluid-filled cavity that appeared to arise from the prostate. Computed tomography revealed the cavity to be consistent with an enlarged uterine body, arising from the prostate, and showed two structures resembling uterine horns that terminated close to the adjacent testes. The dog had a normal male karyotype, 78 XY. Gonadohysterectomy was performed and both the surgical and the histological findings confirmed the presence of a uterus in this male animal, resulting in a diagnosis of persistent Mullerian duct syndrome (PMDS). The enlarged intra-abdominal testis contained a Sertoli cell tumour. Computed tomography proved to be an excellent diagnostic tool for PMDS.

Effects of aging on brainstem responses to toneburst auditory stimuli: a cross-sectional and longitudinal study in dogs.

BACKGROUND It is assumed that the hearing of dogs becomes impaired with advancing age, but little is known about the prevalence and electrophysiologic characteristics of presbycusis in this species. HYPOTHESIS As in humans, hearing in dogs becomes impaired with aging across the entire frequency range, but primarily in the high-frequency area. This change can be assessed quantitatively by brainstem-evoked response audiometry (BERA). ANIMALS Three groups of 10 mixed-breed dogs with similar body weights but different mean ages were used. At the start of the study, the mean age was 1.9 years (range, 0.9-3.4) in group I, 5.7 years (3.5-7) in group II, and 12.7 years (11-14) in group III. METHODS In a cross-sectional study, the BERA audiograms obtained with toneburst stimuli were compared among the 3 groups. In a longitudinal study, changes in auditory thresholds of group II dogs were followed for 7 years. RESULTS Thresholds were significantly higher in group III than in groups I and II at all frequencies tested, and higher in group II than in group I at 4 kHz. The audiograms in group II indicated a progressive increase in thresholds associated with aging starting around 8-10 years of age and most pronounced in the middle- to high-frequency region (8-32 kHz). CONCLUSIONS AND CLINICAL IMPORTANCE Age-related hearing loss in these dogs started around 8-10 years of age and encompassed the entire frequency range, but started and progressed most rapidly in the middle- to high-frequency area. Its progression can be followed by BERA with frequency-specific stimulation.

Evidence of Inheritance of Intrahepatic Portosystemic Shunts in Irish Wolfhounds

BACKGROUND The etiogenesis of congenital portosystemic shunt in dogs is not understood. In Irish Wolfhounds, intrahepatic portosystemic shunt (IHPSS) is thought to be hereditary, but the mode of inheritance is unknown. OBJECTIVES To document the genetic background and investigate the potential mode of inheritance of IHPSS in Irish Wolfhounds. ANIMALS Three mature, privately owned, affected siblings and their progeny produced in 2 litters. METHODS Prospective, observational study. Two test matings of 1 affected sire with 2 of his affected sisters were used to determine the inheritance pattern. Affection status was determined by measuring venous blood ammonia concentrations, detection of the shunt by ultrasonography and confirmation during surgical attenuation of the intrahepatic shunting vessel. RESULTS In 1 litter of 5 pups all had an IHPSS. In the other litter 5 of 11 pups were affected. Both left- and right-sided shunts occurred in both litters. No sex predisposition was evident among affected dogs. CONCLUSIONS AND CLINICAL IMPORTANCE Our results show that IHPSS in Irish Wolfhounds is a familial disorder that is likely genetic. It is unlikely that the mode of inheritance is monogenic. A digenic, triallelic trait could explain the observed occurrence of IHPSS but other modes of inheritance cannot be excluded.