Neurological dysfunction in three dogs and one cat following attenuation of intrahepatic portosystemic shunts

Neurological consequences after portosystemic shunt attenuation in cats: A meta-analysis study

Neurological symptoms that occur after treatment of portosystemic shunts, in cats, known as post-attenuation neurological signs (PANS) can be quite severe. This study seeks to analyze a better understanding of the neurological outcomes that result from reducing portosystemic shunts in felines and provide insights that could guide future clinical approaches and treatment strategies for congenital portosystemic shunts (CPSS).The research utilized the MOOSE Checklist as a guide. PubMed/MEDLINE, Web of Science ScienceDirect, Embase, Scopus, ProQuest, and Google Scholar were used. The study investigated diversity using variance, Cochran Q tests with Applied fixed effects, and random effects models. A meta-regression model identified contributors. Eggers test funnel plot and Beggs test for asymmetry addressed publication bias. 12 high-quality studies were discovered from 664 research papers. This research covered years, shunt morphology, and surgery. PANS occurred 38.9 % of the time in cats, while PAS occurred 20.2 %. The overall PANS mortality rate was 17 %, while PAS was 37.2 %. The complete ligation technique was most common in subgroup analysis. PANS occurrence ranged from 26.8 % to 56.5 % in cats with congenital extrahepatic portosystemic shunts The cause of PANS in cats is still unknown, and there is only limited evidence to justify the use of preventive antiepileptic medications such as levetiracetam. The treatment primarily aims to control neurologic symptoms, and the long-term outlook varies, with the potential for the reappearance of symptoms.

ACVIM Consensus Statement on the management of status epilepticus and cluster seizures in dogs and cats

BACKGROUND

Seizure emergencies (ie, status epilepticus [SE] and cluster seizures [CS]), are common challenging disorders with complex pathophysiology, rapidly progressive drug-resistant and self-sustaining character, and high morbidity and mortality. Current treatment approaches are characterized by considerable variations, but official guidelines are lacking.

OBJECTIVES

To establish evidence-based guidelines and an agreement among board-certified specialists for the appropriate management of SE and CS in dogs and cats.

ANIMALS

None.

MATERIALS AND METHODS

A panel of 5 specialists was formed to assess and summarize evidence in the peer-reviewed literature with the aim to establish consensus clinical recommendations. Evidence from veterinary pharmacokinetic studies, basic research, and human medicine also was used to support the panel's recommendations, especially for the interventions where veterinary clinical evidence was lacking.

RESULTS

The majority of the evidence was on the first-line management (ie, benzodiazepines and their various administration routes) in both species. Overall, there was less evidence available on the management of emergency seizure disorders in cats in contrast to dogs. Most recommendations made by the panel were supported by a combination of a moderate level of veterinary clinical evidence and pharmacokinetic data as well as studies in humans and basic research studies.

CONCLUSIONS AND CLINICAL RELEVANCE

Successful management of seizure emergencies should include an early, rapid, and stage-based treatment approach consisting of interventions with moderate to preferably high ACVIM recommendations; management of complications and underlying causes related to seizure emergencies should accompany antiseizure medications.

Congenital Portosystemic Shunts in Dogs and Cats: Treatment, Complications and Prognosis

Congenital portosystemic shunts (CPSS) are a common vascular anomaly of the liver in dogs and cats. Clinical signs of CPSS are non-specific and may wax and wane, while laboratory findings can raise the clinical suspicion for CPSS, but they are also not specific. Definitive diagnosis will be established by evaluation of liver function tests and diagnostic imaging. The aim of this article is to review the management, both medical and surgical, complications, and prognosis of CPSS in dogs and cats. Attenuation of the CPSS is the treatment of choice and may be performed by open surgical intervention using ameroid ring constrictors, thin film banding, and partial or complete suture ligation or by percutaneous transvenous coil embolization. There is no strong evidence to recommend one surgical technique over another. Medical treatment strategies include administration of non-absorbable disaccharides (i.e., lactulose), antibiotics, and dietary changes, and are indicated for pre-surgical stabilization or when surgical intervention is not feasible. After CPSS attenuation, short- and long-term post-surgical complications may be seen, such as post-operative seizures and recurrence of clinical signs, respectively. Prognosis after surgical attenuation of CPSS is generally favorable for dogs and fair for cats.

Postattenuation neurologic signs after surgical correction of congenital portosystemic shunts in cats: A narrative review

Development of postattenuation neurological signs (PANS) is a potentially severe complication after surgical attenuation of congenital portosystemic shunts in cats. This review summarizes findings of 15 publications that report occurrence of PANS in cats. PANS includes seizures but also milder neurologic signs such as blindness, ataxia, abnormal behavior, tremors, and twitching. Incidence of PANS and specifically postattenuation seizures in studies including a minimum of five cats ranges from 14.3% to 62.0% and 0% to 32.0%, respectively. Etiology of PANS in cats is unknown, however, several hypotheses have been proposed including central nervous system disease/derangement, perioperative hypoglycemia and electrolyte disturbances, and postoperative portal hypertension. A number of possible risk factors have been identified including lower grades of intraoperative postocclusion mesenteric portovenography and osmolality at 24 h postoperatively. Evidence for use of prophylactic antiepileptics such as levetiracetam to prevent or reduce incidence of PANS in cats is limited and does not support their use. Because the cause is unknown, treatment is aimed at controlling neurologic signs, preventing progression to more severe signs, and providing general supportive care. Prospective studies comparing the efficacy of different antiepileptics for treatment of PANS in cats are required. Prognosis for recovery is variable and dependent on severity of neurologic signs. For cats surviving to discharge, long-term survival is possible but persistence or recurrence of neurologic signs in the long-term is not uncommon.

Diagnosis of post-attenuation neurological signs syndrome in a cat with refractory status epilepticus and clinical response to therapeutic plasma exchange

Case summary

An 8-year-old female spayed British Shorthair cat that underwent surgical portosystemic shunt (PSS) attenuation developed progressive neurological signs 7 days postoperatively. Neurological signs progressed, despite medical management, and seizure activity became rapidly refractory to anticonvulsants. The diagnosis of post-attenuation neurological signs (PANS) was made based on the timing of the occurrence of clinical signs following surgery, absence of hyperammonaemia and suggestive MRI findings of the brain. The cat developed status epilepticus that required treatment with general anaesthesia and mechanical ventilation, from which the cat could not be effectively weaned without the recurrence of seizures. Therapeutic plasma exchange (TPE) was performed as a rescue therapy for PANS and associated refractory status epilepticus. A total of two plasma volumes were processed during one single TPE session. The seizure activity resolved immediately after the TPE session, the cat showed progressive improvement of neurological signs and remained stable thereafter. No significant complications associated with the TPE were observed. The cat was discharged 11 days after admission and was fully recovered.

Relevance and novel information

This is an unusual report of PANS diagnosed in a cat based on clinical and MRI findings. The cat developed refractory status epilepticus and had a positive outcome following TPE as rescue therapy. The MRI findings in this report could be useful for the diagnosis of PANS in cats. We speculate that TPE could be taken into consideration as a possible therapeutic intervention in PANS syndrome.

Long-term outcome and quality of life of dogs that developed neurologic signs after surgical treatment of a congenital portosystemic shunt: 50 cases (2005-2020)

OBJECTIVE

To determine survival time and quality of life of dogs that developed postattenuation neurologic signs (PANS) after surgical treatment of a single congenital portosystemic shunt and survived at least 30 days and identify whether neurologic signs present at the time of discharge would resolve or reoccur.

ANIMALS

50 client-owned dogs.

PROCEDURES

Medical records were retrospectively reviewed, and follow-up data relating to neurologic signs and seizure activity were obtained. Owners were asked to complete a questionnaire related to the presence of neurologic signs, including seizures, and their dog's quality of life.

RESULTS

Thirty of the 50 (60%) dogs had postattenuation seizures with or without other nonseizure neurologic signs, and 20 (40%) had neurologic signs other than seizures. Neurologic signs had fully resolved by the time of discharge in 24 (48%) dogs. Signs resolved in 18 of the remaining 26 (69%) dogs that still had PANS other than seizures at the time of discharge. Seizures reoccurred in 15 of the 30 dogs that had postattenuation seizures. Twenty-seven of 33 (82%) owners graded their dog's long-term (> 30 days after surgery) quality-of-life as high. Forty-five (90%) dogs survived > 6 months. Most (29/43 [67%]) neurologic signs (other than seizures) present at the time of hospital discharge resolved.

CLINICAL RELEVANCE

Findings highlighted that survival times of > 6 months and a high QOL can be achieved in most dogs with PANS that survive at least 30 days. Most neurologic signs other than seizures resolved within 1 month postoperatively. Half of the dogs with postattenuation seizures had a reoccurrence.

Postattenuation neurologic signs after surgical attenuation of congenital portosystemic shunts in dogs: A review

The development of postattenuation neurologic signs (PANS) is a poorly understood and potentially devastating complication after surgical attenuation of congenital portosystemic shunts in dogs. Postattenuation neurologic signs include seizures but also more subtle neurologic signs such as depression, behavioral changes, tremors, and twitching. They most commonly occur within 7 days postoperatively and are typically unrelated to hyperammonemia, hypoglycemia, or electrolyte disturbances. This narrative review summarizes the findings of 50 publications from 1988-2020 that report occurrence of PANS. While most published reports included only dogs affected by postattenuation seizures (PAS), others included dogs with any form of PANS. Overall, PANS (including PAS) affected 1.6%-27.3% of dogs, whereas incidence of PAS ranged from 0%-18.2%. The etiology of PANS remains unknown; however, several theories have been proposed. Risk factors include preoperative hepatic encephalopathy, increasing age, and possibly certain breeds and extrahepatic shunt morphology. There is increasing evidence that prophylactic antiepileptic drugs do not prevent PANS. Treatment is centered around controlling neurologic signs with antiepileptic drugs and providing supportive intensive care. The 30-day survival rate in studies that included a minimum of four dogs affected by PANS was 0%-100% (median, 50.0%) and 0%-75.0% (median, 37.5%) for those with PAS. Mortality associated with PANS was typically related to occurrence of generalized seizure activity. Prognostic factors positively associated with short-term survival included having a history of preoperative seizures and development of focal seizures only. If affected dogs survived to discharge, survival for several years was possible, and the majority of neurologic signs manifested as part of the phenomenon of PANS appeared to resolve.

Continuous rate infusion of midazolam as emergent treatment for seizures in dogs

Background

Midazolam delivered by continuous rate infusion (CRI) might be effective in dogs with cluster seizures (CS) or status epilepticus (SE).

Objective

To describe the use and safety of midazolam CRI in dogs with CS or SE.

Animals

One‐hundred six client‐owned dogs presenting to a veterinary teaching hospital with CS or SE.

Methods

Retrospective review of medical records for dogs with CS or SE treated with a midazolam CRI.

Results

Seventy‐nine dogs presented with CS and 27 dogs had SE. Seizure control was achieved in 82/106 dogs (77.4%) receiving a midazolam CRI. The median dose associated with seizure control was 0.3 mg/kg/h (range, 0.1‐2.5 mg/kg/h). The median duration of CRI was 25 hours (range, 2‐96 hours). Seizures were controlled in 34/40 dogs (85%) with idiopathic epilepsy, 32/43 dogs (74%) with structural epilepsy, 12/16 dogs (75%) with unknown epilepsy, and 4/7 dogs (57%) with reactive seizures (P = .20). Seizure control was achieved in 81% of dogs with CS and 67% in dogs with SE (P = .18). Dogs with idiopathic/unknown epilepsy were more likely to survive than those with structural epilepsy (87% vs 63%, P = .009). Adverse effects were reported in 24 dogs (22.6%) and were mild in all cases.

Conclusions and Clinical Importance

Midazolam CRI is apparently safe and might be an effective treatment in dogs with CS or SE.

Astrocyte lesions in cerebral cortex and cerebellum of dogs with congenital ortosystemic shunting

Background

Congenital portosystemic shunt (cPSS) is one of the most common congenital disorders diagnosed in dogs. Hepatic encephalopathy (HE) is a frequent complication in dogs with a cPSS and is a major cause of morbidity and mortality. Despite HE been a major cause of morbidity in dogs with a cPSS, little is known about the cellular changes that occur in the central nervous system of dogs with a cPSS.

Objectives

The objective of this study was to characterise the histological changes in the cerebral cortex and cerebellum of dogs with cPSS with particular emphasis on astrocyte morphology.

Methods

Eight dogs with a confirmed cPSS were included in the study.

Results

Six dogs had substantial numbers of Alzheimer type II astrocytes and all cases had increased immunoreactivity for glial fibrillary acidic protein in the cerebral cortex, even if there were minimal other morphological changes.

Conclusions

This study demonstrates that dogs with a cPSS have marked cellular changes in the cerebral cortex and cerebellum. The cellular changes that occur in the cerebral cortex and cerebellum of dogs with spontaneously arising HE are similar to changes which occur in humans with HE, further validating dogs with a cPSS as a good model for human HE.

Prognostic factors for short-term survival of dogs that experience postattenuation seizures after surgical correction of single congenital extrahepatic portosystemic shunts: 93 cases (2005-2018)

OBJECTIVE

To identify prognostic factors for short-term survival of dogs that experience seizures within 7 days after surgical correction of single congenital extrahepatic portosystemic shunts (cEHPSS).

STUDY DESIGN

Multi-institutional retrospective study.

SAMPLE POPULATION

Ninety-three client-owned dogs.

METHODS

Medical records at 14 veterinary institutions were reviewed to identify dogs that underwent surgical attenuation of a single cEHPSS from January 1, 2005 through February 28, 2018 and experienced postattenuation seizures (PAS) within 7 days postoperatively. Logistic regression analysis was performed to identify factors associated with 1-month survival. Factors investigated included participating institution, signalment, shunt morphology, concurrent/historical conditions, presence of preoperative neurologic signs, presence of preoperative seizures, aspects of preoperative medical management, surgical details including method and degree of shunt attenuation, type of PAS (focal only or generalized ± focal), drugs administered as part of the treatment of PAS, and development of complications during treatment of PAS.

RESULTS

Thirty (32.3%) dogs survived to 30 days. Seventy-six (81.7%) dogs experienced generalized PAS. Factors positively associated with short-term survival included having a history of preoperative seizures (P = .004) and development of focal PAS only (P = .0003). Most nonsurvivors were humanely euthanized because of uncontrolled or recurrent seizures.

CONCLUSION

Dogs that experienced PAS that had a history of preoperative seizures and those that experienced focal PAS only had significantly improved short-term survival.

CLINICAL SIGNIFICANCE

The results of this study provide information that will help in the counseling of owners who seek treatment for PAS after surgical correction of cEHPSS. © 2020 The American College of Veterinary Surgeons.

Hepatic encephalopathy in dogs and cats

OBJECTIVE

To comparatively review the pathogenesis, clinical presentation, diagnosis, and management of hepatic encephalopathy (HE) in dogs and cats.

DATA SOURCES

The Medline database was searched for articles related to HE in people, dogs, and cats. Articles published within the last 5 years were given special importance.

HUMAN DATA SYNTHESIS

The pathogenesis of HE is complex and incompletely understood, but ammonia appears to play a central role. Hyperammonemia leads to accumulation of glutamine in astrocytes, with subsequent astrocyte swelling and neurological dysfunction. The development of HE in patients with hepatic cirrhosis is a poor prognostic indicator. The fermentable disaccharide lactulose and the antimicrobial rifaximin are US Food and Drug Administration approved treatments for human HE. Severe protein restriction is no longer recommended for patients with this condition.

VETERINARY DATA SYNTHESIS

HE is often associated with portosystemic shunting in dogs and cats. Ammonia plays a central role in the pathogenesis of HE in dogs and cats, but other factors such as manganese and endogenous benzodiazepines may also contribute. Recently, a soy protein-based diet was found to be beneficial in treating canine HE. Severe dietary protein restriction is likely to be detrimental in affected animals. There have been no clinical trials of drugs routinely used in the management HE in veterinary medicine, but lactulose and antimicrobials such as metronidazole are well-established treatments.

CONCLUSIONS

HE is a potentially life-threatening condition that is probably underdiagnosed in companion animals. Although various treatment recommendations have been proposed, there is a lack of evidence in the veterinary literature regarding optimal strategies for the management of this condition. As our understanding of the pathogenesis of HE in dogs and cats evolves, novel diagnostic tests and therapeutic agents may become available.

Clinical presentation and management of moxidectin toxicity in two dogs

Moxidectin is a macrocyclic lactone related to ivermectin used in horses and dogs for endoparasite treatment and prophylaxis. The clinical and neurological presentation of moxidectin toxicity in two dogs following inadvertent poisoning with a moxidectin-containing equine de-worming medication is reported here. In both the dogs, the predominant clinical signs were generalised tremors and ataxia. Moxidectin exerts its neurotoxic effects in mammals by potentiating the effect of gamma-aminobutyric acid and, consistent with this, both the dogs demonstrated a poor response to treatment with diazepam. It would be more appropriate to avoid gamma-aminobutyric acid agonists, such as benzodiazepines and barbiturates, in dogs with moxidectin toxicity and consider using anaesthetic agents with a different mode of action, such as propofol. The prognosis in dogs accidentally exposed to moxidectin-containing equine de-worming medication appears to be excellent if the cause of the neurotoxicity is correctly identified and the case is appropriately managed.

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.