cis-Atracurium in dogs with and without porto-systemic shunts

OBJECTIVE: To evaluate the non-depolarizing neuromuscular blocking drug cis-atracurium in dogs with porto-systemic shunts, and to compare it in clinically normal animals. ANIMALS: Thirteen dogs of mixed breed and sex, aged between 3 and 31 months old, weighing 2.2-25.5 kg, with ASA physical status II-IV, and undergoing surgical attenuation of porto-systemic shunt. A control group of 11 bitches of mixed breed, between 8 and 60 months old, and weighing 4.5-41.0 kg, all ASA physical status I, undergoing routine ovarohysterectomy were also studied. MATERIALS AND METHODS: Pre-anaesthetic medication was an opioid analgesic, given either alone or in combination with acepromazine. Following induction of general anaesthesia with intravenous (IV) propofol and oro-tracheal intubation, anaesthesia was maintained using isoflurane in either oxygen or oxygen and nitrous oxide. Ventilation was controlled. The train of four (TOF) technique was used to monitor neuromuscular blockade. An initial dose of 0.1 mg kg(-1)cis-atracurium was given IV and additional doses of 0.03 mg kg(-1)cis-atracurium were administered when at least one twitch of the TOF was present. RESULTS: Except for one dog that was killed during surgery because its anomaly was inoperable, all animals recovered satisfactorily from anaesthesia and surgery. In dogs with porto-systemic shunt, onset of neuromuscular blockade was 3.1 +/- 1.1 minutes (mean +/- SD) and in control dogs was 3.4 +/- 0.7 minutes (not significantly different). Neuromuscular blockade lasted 34 +/- 13 minutes in dogs with porto-systemic shunt and 29 +/- 17 minutes in control dogs (not significantly different). CONCLUSIONS: The presence of porto-systemic shunt did not affect the rate of onset or duration of action of cis-atracurium. CLINICAL RELEVANCE: cis-Atracurium may have a use in veterinary anaesthesia for producing neuromuscular blockade in dogs with hepatic insufficiency, including those with porto-systemic shunt.     

Effect of breed on anatomy of portosystemic shunts resulting from congenital diseases in dogs and cats: a review of 242 cases

OBJECTIVE: To evaluate the effect of species and breed on the anatomy of portosystemic vascular anomalies in dogs and cats. DESIGN: Retrospective study of 233 dogs and nine cats presenting to the University Veterinary Centre, Sydney. METHODS: Case records were evaluated for breed, sex, age, anatomical and histological diagnosis. Cases were included when a portosystemic vascular anomaly resulted from a congenital or developmental abnormality of the liver or portal venous system. RESULTS: Disease conditions included single congenital portosystemic shunt with patent portal vasculature (214 dogs, nine cats), portal vein aplasia (nine dogs), multiple acquired shunts resulting from portal vein hypoplasia (seven dogs), biliary atresia (one dog) and microvascular dysplasia (one dog). One Maltese had a single, congenital shunt and multiple acquired shunts resulting from hepatic cirrhosis. Breeds that were significantly over-represented included the Maltese, Silky Terrier, Australian Cattle Dog, Bichon Frise, Shih Tzu, Miniature Schnauzer, Border Collie, Jack Russell Terrier, Irish Wolfhound and Himalayan cat. Bichon Frise with shunts were significantly more likely to be female than male (12:2, P < 0.001). Two hundred and fourteen dogs (91.4%), and all cats, had shunts that were amenable to attenuation. Inoperable shunts occurred in 19 dogs (8.2%). Fifty six of 61 (92%) operable shunts in large breed dogs were intrahepatic, versus 10/153 (7%) in small breeds (P < 0.0001). Breeds that were not predisposed to portosystemic shunts were significantly more likely to have unusual or inoperable shunts than dogs from predisposed breeds (29% versus 7.6%, P < 0.0001). No significant relationship between breed and shunt type could be determined in cats. CONCLUSION: Breed has a significant influence on shunt anatomy in dogs. Animals presenting with signs of portosystemic shunting may suffer from a wide range of operable or inoperable conditions. Veterinarians should be aware that unusual or inoperable shunts are much more likely to occur in breeds that are not predisposed to congenital portosystemic shunts.     

Congenital portosystemic shunts in dogs and cats

Congenital portosystemic shunts (PPS) are abnormal vascular communications that allow blood from the intestine to bypass the liver, and are classified as intrahepatic or extrahepatic. Clinical signs are generally related to the nervous, gastrointestinal or urinary systems, and are often vague. In addition, changes present on routine blood analysis are often mild and non-specific. For this reason, alternative tests are required for a diagnosis. Diagnostic tests include serum bile-acid concentrations, ammonia tolerance test, portography, ultrasonography and/or scintigraphy. Medical therapy involves reducing absorption of encephalopathic toxins from the gastrointestinal tract and may prolong survival. Surgical therapy is aimed at attenuation of the shunting vessel and provides improved survival rates. The traditional approach has been complete or partial ligation of the shunt. More recent approaches have involved slow, progressive attenuation with ameroid constrictors or cellophane banding. Overall, prognosis following surgical therapy is good in dogs and fair in cats.     

Outcomes of cellophane banding for congenital portosystemic shunts in 106 dogs and 5 cats

OBJECTIVE : To report outcomes after cellophane banding of single congenital portosystemic shunts in dogs and cats. STUDY DESIGN : Retrospective study of sequential cases. ANIMALS : One hundred and six dogs and five cats. METHODS : Medical records were reviewed for breed, sex, age at surgery, shunt anatomy, results of pre- and postoperative biochemical analysis, development of postligation neurologic dysfunction, portal hypertension or other serious complications, and the owners' perception of their animal's response to surgery. RESULTS : Ninety-five dogs and all 5 cats had extrahepatic shunts. Eleven dogs had intrahepatic shunts. Six dogs (5.5%) died as a result of surgery from portal hypertension (2 dogs), postligation neurologic dysfunction (2), splenic hemorrhage (1) and suspected narcotic overdose (1). Serious complications were more common in dogs with intrahepatic shunts than those with extrahepatic shunts (P=.002). Postligation neurologic dysfunction necessitated treatment in 10 dogs and 1 cat; 8 dogs and the cat survived. Clinical signs attributed to portosystemic shunting resolved or were substantially attenuated in all survivors. Postoperative serum bile acid concentrations or results of ammonia tolerance testing were available for 88 animals; 74 (84%) were normal and 14 (16%) were abnormal. Multiple acquired shunts were documented in two animals. CONCLUSIONS : Cellophane banding is a safe and effective alternative to other methods of attenuation. CLINICAL RELEVANCE : Slow occlusion of portosystemic shunts using a variety of methods is being evaluated world wide. Cellophane banding is a relatively simple procedure with comparable safety and efficacy to previously reported techniques.     

Glomerulopathy in dogs with congenital portosystemic shunts

Kidney specimens from 12 dogs with congenital portosystemic shunts were examined histologically. Glomerulopathy of variable severity was present in the kidney sections of all 12. Marked irregular thickening of the glomerular capillary wall was the most prominent pathological change, the renal interstitium being largely unaffected. The severity of lesions was not correlated with the age of dogs at the time of necropsy. An immunoperoxidase technique failed to demonstrate significant IgA or IgG deposition in affected glomeruli. Proteinuria was generally mild or absent despite significant glomerular lesions, except in dogs with concurrent urinary tract infection.     

Methods of gradual vascular occlusion and their applications in treatment of congenital portosystemic shunts in dogs: a review

OBJECTIVE: To provide a comprehensive review of the experimental and clinical data related to gradual vascular occlusion of congenital portosystemic shunts (CPS) in dogs. STUDY DESIGN: Literature review. METHODS: PubMed literature search (1966-2004). RESULTS: Surgical intervention and complete vascular occlusion have been recommended for CPS therapy in dogs; however, acute complete ligation of CPS is often associated with life-threatening portal hypertension. Recently, several investigators have attempted to reduce the risk of postoperative portal hypertension by using gradual vascular occlusion. Successful vascular occlusion has been achieved using partial ligation with silk suture, ameroid constrictors, cellophane bands, thrombogenic coils and hydraulic vascular occluders. Objective comparisons of the reliability and rate of vascular occlusion produced by each of these methods have been limited by differences in experimental models and a lack of definitive follow up evaluation in some clinical studies. CONCLUSIONS: Gradual vascular occlusion is widely used in the clinical treatment of CPS in dogs. Objective evaluation of the experimental and clinical data on each of the techniques for gradual vascular occlusion is necessary for informed clinical practice and for the planning of future research into this important area. CLINICAL RELEVANCE: Even from the limited data available, it is clear that the ideal method for gradual vascular occlusion of CPS has yet to be identified.     

Congenital hypothyroidism of dogs and cats: a review

Congenital hypothyroidism is a rare and underdiagnosed congenital endocrine disorder in dogs and cats and the true incidence is unknown. The disorder may cause a range of clinical signs depending on the primary defect, which affect production of thyroid hormones; some cases present when adult. Hallmark clinical signs of congenital hypothyroidism are mental impairment and skeletal developmental abnormalities, resulting in disproportionate dwarfism; goitre may or may not be present. Documented causes of congenital hypothyroidism in dogs include deficiency of, or unresponsiveness to, thyrotropin-releasing hormone (TRH) or thyroid-stimulating hormone (TSH), thyroid dysgenesis, dyshormonogenesis and iodine deficiency. In cats, TSH unresponsiveness, thyroid dysgenesis, dyshormonogenesis and iodine deficiency have been confirmed. Adequate replacement therapy results in a successful outcome in the majority of cases, especially when started early in life, as permanent developmental abnormalities can be prevented. This review describes reported cases in dogs and cats, diagnostic investigation, and recommendations for treatment.     

Iron homeostasis and disorders in dogs and cats: a review

Iron is an essential element for nearly all living organisms and disruption of iron homeostasis can lead to a number of clinical manifestations. Iron is used in the formation of both hemoglobin and myoglobin, as well as numerous enzyme systems of the body. Disorders of iron in the body include iron deficiency anemia, anemia of inflammatory disease, and iron overload. This article reviews normal iron metabolism, disease syndromes of iron imbalance, diagnostic testing, and treatment of either iron deficiency or excess. Recent advances in diagnosing iron deficiency using reticulocyte indices are reviewed.     

Hemostatic profiles in 39 dogs with congenital portosystemic shunts

OBJECTIVES: To determine if there were significant changes in prothrombin time (PT), partial thromboplastin time (PTT), and fibrinogen levels in dogs with naturally occurring congenital portosystemic shunts (CPSS) and to determine if there was any association between these values, serum albumin concentration, and the ability to attenuate the shunt vessel. STUDY DESIGN: Retrospective clinical study. ANIMALS: Thirty-nine client-owned dogs. METHODS: Medical records of 60 dogs with confirmed CPSS were retrospectively evaluated. Hemostatic profiles had been performed before surgery in 39 cases. RESULTS: Dogs with CPSS had significantly higher values for PTT (P < .001) when compared with normal dogs. Of the total number of dogs, 64.1% had a PTT greater than 16 seconds (25/39). PTT was prolonged by 25% or more in 51.3% of dogs (20/39). PT tended to be higher in dogs with CPSS (P = .036), although only 7.7% (3/39) of dogs had a PT greater than 12 seconds (the maximum reference value). Dogs with CPSS had significantly lower values for albumin and fibrinogen (P < .001). Platelet numbers were within the normal range in 87.2% of cases (34/39). Of the 5 dogs with platelet numbers outside the normal range, 3 were mildly thrombocytopenic. Fibrin degradation product concentrations were not elevated in any dogs tested (N = 22). There was no significant difference in any of the measured variables between dogs with extrahepatic shunts and those with intrahepatic shunts (P > .1). For PT, PTT, albumin, and fibrinogen, there was no significant difference between dogs that underwent total, partial, or no attenuation (P > .3). CONCLUSIONS: Dogs with CPSS have a tendency to have a prolonged PTT. There was no significant difference in hemostatic profile results between dogs with intrahepatic shunts versus extrahepatic shunts. Preoperative hemostatic profile abnormalities were not useful as predictors of ability to attenuate CPSS. CLINICAL RELEVANCE: Prolonged PTT was not associated with bleeding tendencies in any of the dogs. Assays of individual clotting factors may help to further characterize the abnormalities present in animals with CPSS and may identify specific factor deficiencies. This might enable identification of a noninvasive diagnostic or prognostic indicator.     

The pathophysiology and laboratory diagnosis of congenital portosystemic shunts in dogs

Abstract Congenital portosystemic shunts generally arise as single vascular anomalies that cause the portal blood to bypass the liver and enter the systemic venous circulation directly. The liver is primarily affected, as it is deprived of perfusion by portal hepatotrophic factors such as insulin, glucagon, and amino acids. There is progressive hepatic atrophy, and as a consequence, dysfunction. Hepatic encephalopathy can result from increased levels of ammonia and gamma-aminobutyric acid within the systemic circulation. Variably toxic amines, captans and short chain fatty acids may act as false neurotransmitters. Hypoglycaemia will exacerbate the effects of these substances. Increased concentrations of ammonia and uric acid in the urine predispose to the precipitation of ammonium biurate crystals and the formation of calculi. Haematological changes include anaemia, microcytosis, hypoproteinaemia, leucocytosis, and coagulation abnormalities. Gastrointestinal effects are common. They may be displayed as anorexia, vomiting, ptyalism, pica, diarrhoea, or polyphagia. Most dogs are less than 1 year of age at initial presentation. Diagnosis from a laboratory viewpoint will involve a consideration of the history, clinical findings, haematology, serum biochemistry and urinalysis. If the findings are suggestive of a congenital portosystemic shunt, the demonstration of elevated fasting or, more consistently, post-prandial serum bile acid concentrations, and subsequent histological examination of a liver biopsy will provide a definitive diagnosis.     

Diagnostic approach to hematuria in dogs and cats.

Hematuria indicates the presence of urogenital disease in dogs and cats. Persistent hematuria (macroscopic or microscopic) should be evaluated to determine the source of bleeding and the underlying cause so that appropriate treatment can be recommended. Results of the history and physical examination often help to localize disease to the urinary tract (either upper or lower) or genital tract.Additional diagnostic evaluation, including laboratory testing(eg, urinalysis, urine culture), diagnostic imaging (eg, abdominal radiographs, ultrasound), and collection of tissues for cytologic or histopathologic evaluation, may be needed to identify the underlying cause. If a thorough evaluation fails to reveal the source or cause of hematuria, exploratory celiotomy should be considered,especially if idiopathic renal hematuria is possible.     

Intussusception in dogs and cats: A review of 36 cases

Intussusception is recognized as a common cause of bowel obstruction in small animals. This study documents the clinical and surgical findings in nine cats and 27 dogs diagnosed as having intussusception. The main purposes of the study were to define the predisposing causes and clinical signs of intussusception and to evaluate various surgical techniques commonly employed in its treatment. No common predisposing cause could be established. Diagnosis of intussusception was based most often on clinical signs of bowel obstruction in association with the palpable abdominal mass. The majority of the intussusceptions involved the enterocolic junction. Formation of adhesions was more frequent in cats. Surgical treatments included simple reduction, manual reduction with plication, intestinal resection/anastomosis, and intestinal resection/anastamosis with plication. There was no statistically significant difference (p>0.05) in the recurrence rate of the intussusceptions when the various surgical techniques were compared. Recurrence of an intussusception was not related to either the bowel segment involved or whether a simple reduction, bowel resection, or intestinal plication was performed at the initial surgery.     

Complications and long-term outcomes of the ligation of congenital portosystemic shunts in 49 cats

Only two of 49 cats undergoing surgical ligation of congenital extra- and intrahepatic portosystemic shunts died perioperatively, a mortality rate comparable with the mortality rates of dogs undergoing surgical attenuation of congenital portosystemic shunts and cats in which the shunts are attenuated with an ameroid ring constrictor. Thirty (83 per cent) of the 36 cats for which long-term information was available were still alive at a median follow-up period of 47 months (range six to 105 months); the outcome was excellent (no clinical signs) in 20 of them (median follow-up 37 months, range six to 105 months) and good (minimal clinical signs) in seven (median follow-up 39 months, range 10 to 73 months) and none of these 27 cats was on any long-term medication or special diet. The only major cause of morbidity was the development of neurological signs in 18 (37 per cent) of the cats. These included seizures and a wide variety of other neurological signs, and their development and persistence was not affected by the presence of preoperative seizures, the type of shunt, the degree of shunt attenuation or the age of the cat. The serum concentrations of ammonia and preprandial bile acids were normal or significantly below normal in the cats with neurological signs. Liver histopathology was similar in the cats with and without neurological signs. Ten (56 per cent) of the 18 cats that developed neurological signs recovered normal neurological function long term.     

Ultrasonographic evaluation of partially attenuated congenital extrahepatic portosystemic shunts in 14 dogs

Doppler ultrasonography was used to evaluate the portal vein in 14 dogs before, immediately after and four weeks after a partial ligation of a congenital extrahepatic portocaval shunt. By four weeks after the operation, the hepatofugal or zero flow in the portal vein segment cranial to the shunt origin had become a hepatopetal flow in 13 of the dogs, which became clinically healthy. The other dog continued to have a hepatofugal flow in the portal vein cranial to the origin of the shunt and continued to show clinical signs of hepatic encephalopathy. The shunt remained functional in six of the dogs, and three of them developed portosystemic collaterals in addition. In the other eight dogs the patent shunt was non-functional, because a hepatopetal flow was detected in the shunt adjacent to the portal vein. This flow was the result of the splenic vein entering the shunt, and the splenic blood dividing; some flowed via the shunt towards the portal vein, preventing the portal blood from shunting, and the rest flowed via the attenuated shunt segment to the caudal vena cava. Shunting of the splenic venous blood was clinically insignificant.     

Sacral fractures in dogs and cats: a classification scheme and review of 51 cases

classification scheme for sacral fractures was based on a review of sacral fractures in 34 dogs and 17 cats. They were classified into five categories based on their radiographic appearance on standard lateral and ventrodorsal radiographs of the pelvis. Concomitant pelvic injuries were commonly observed: 32 per cent of dogs had a fracture of an ilium and 65 per cent of cats had unior bilateral sacroiliac subluxation. Neurological deficits were common where the fractures traversed the spinal canal or sacral foraminae. Comparison is made between sacral fractures in dogs and cats, and humans.