Michael Tivers

A retrospective study of surgically treated cases of septic peritonitis in the cat (2000–2007)

OBJECTIVES To review aetiology, clinical signs and outcome of cats surgically treated for septic peritonitis (2000-2007). METHODS A retrospective study. Inclusion criteria were the identification of intracellular bacteria and degenerate neutrophils and/or a positive culture from abdominal fluid and exploratory coeliotomy. Aetiology, clinical signs, haematological and biochemical parameters, surgical treatment and outcome were recorded and analysed. RESULTS Twenty-six cats fulfilled the inclusion criteria. Abdominal pain was reported in 10 (38 per cent) and vomiting was reported in 11 (42 per cent) of the cats. The most common aetiology was trauma (31 per cent). The principal source of contamination was the gastrointestinal tract. Hyperlactataemia, hypoproteinaemia and hyperglycaemia were reported in 9, 13 and 14 of the 26 cases, respectively. Non-survivors had significantly higher blood lactate concentrations than survivors (P=0.02). Nineteen cats were managed with primary closure, two with closed suction drains and three with open peritoneal drainage. Twelve (46 per cent) cats survived to discharge. CLINICAL SIGNIFICANCE In cats, lethargy, depression and anorexia were more common clinical signs than abdominal pain. Lactate level at the time of diagnosis may be a useful prognostic indicator in cats. The proportion of cats that survived was lower than previously reported and owners should be given a guarded prognosis.

Canine stifle positive contrast computed tomography arthrography for assessment of caudal horn meniscal injury: a cadaver study

OBJECTIVE To investigate the use of computed tomography (CT) arthrography in cadaveric canine stifles with particular emphasis on the diagnosis of meniscal injury. STUDY DESIGN Prospective cadaver study. SAMPLE POPULATION Pelvic limbs from adult Beagles (n=10). METHODS After survey CT scan of each stifle oriented in the dorsal plane, positive contrast stifle CT arthrogram (CTA) was performed using the same slice orientation. Each stifle was then randomly allocated into 1 of 2 treatment groups: group A--arthrotomy, cranial cruciate ligament (CCL) transection and simulated injury to the caudal horn of the medial meniscus; group B--arthrotomy and CCL transection only. CT scan was repeated as before and post-arthrotomy images were interpreted by a radiologist unaware of treatment grouping. RESULTS The cranial and caudal cruciate ligaments, medial and lateral menisci, menisco-femoral ligament, and long digital extensor tendon were all identifiable on CTA images. CTA was 90% sensitive and 100% specific for diagnosing simulated caudal horn meniscal injury. CONCLUSIONS Stifle CTA enables identification of intra-articular structures within the stifle and is a reliable method for identifying simulated meniscal injuries in a cadaver model. CLINICAL RELEVANCE CTA imaging of the canine stifle has potential clinical value for detection of meniscal injury.

Impact of Facial Conformation on Canine Health: Brachycephalic Obstructive Airway Syndrome

The domestic dog may be the most morphologically diverse terrestrial mammalian species known to man; pedigree dogs are artificially selected for extreme aesthetics dictated by formal Breed Standards, and breed-related disorders linked to conformation are ubiquitous and diverse. Brachycephaly–foreshortening of the facial skeleton–is a discrete mutation that has been selected for in many popular dog breeds e.g. the Bulldog, Pug, and French Bulldog. A chronic, debilitating respiratory syndrome, whereby soft tissue blocks the airways, predominantly affects dogs with this conformation, and thus is labelled Brachycephalic Obstructive Airway Syndrome (BOAS). Despite the name of the syndrome, scientific evidence quantitatively linking brachycephaly with BOAS is lacking, but it could aid efforts to select for healthier conformations. Here we show, in (1) an exploratory study of 700 dogs of diverse breeds and conformations, and (2) a confirmatory study of 154 brachycephalic dogs, that BOAS risk increases sharply in a non-linear manner as relative muzzle length shortens. BOAS only occurred in dogs whose muzzles comprised less than half their cranial lengths. Thicker neck girths also increased BOAS risk in both populations: a risk factor for human sleep apnoea and not previously realised in dogs; and obesity was found to further increase BOAS risk. This study provides evidence that breeding for brachycephaly leads to an increased risk of BOAS in dogs, with risk increasing as the morphology becomes more exaggerated. As such, dog breeders and buyers should be aware of this risk when selecting dogs, and breeding organisations should actively discourage exaggeration of this high-risk conformation in breed standards and the show ring.

Diagnostic accuracy of positive contrast computed tomography arthrography for the detection of injuries to the medial meniscus in dogs with naturally occurring cranial cruciate ligament insufficiency

OBJECTIVE To assess the usefulness of computed tomography arthrography of the stifle in diagnosing meniscal tears in dogs with cranial cruciate ligament insufficiency. METHODS A prospective clinical study was performed. Dogs were included if they had evidence of cranial cruciate ligament insufficiency or persistent or recurrent lameness following surgery for cranial cruciate ligament insufficiency. Dogs were sedated for a computed tomography scan of the affected stifle, orientated in the dorsal plane. A survey computed tomography scan was followed by a computed tomography arthrogram. A stifle arthrotomy was performed, and the surgical findings were recorded. The computed tomography scans were reviewed by three blinded reviewers, and the results were compared to the surgical findings. RESULTS Twenty-one computed tomography arthrograms from 20 dogs were included. At surgery, damage to the medial meniscus was identified in 14 stifles. Initial interpretation of computed tomography arthrography images was 57 to 64 per cent sensitive and 71 to 100 per cent specific for diagnosing medial meniscal injuries. Interpretation of the images on retrospective analysis was 71 per cent sensitive and 100 per cent specific, with an accuracy of 0.857. CLINICAL SIGNIFICANCE The accuracy of stifle computed tomography arthrography for the diagnosis of tears to the medial meniscus was found to be good. It is a minimally invasive and repeatable technique, which does not require general anaesthesia or specialist training to obtain the images. The ability to reliably diagnose meniscal injury without the need for surgery may be advantageous, particularly in dogs which had previously had surgery for cranial cruciate ligament insufficiency.

Does a fabella-tibial suture alter the outcome for dogs with cranial cruciate ligament insufficiency undergoing arthrotomy and caudal pole medial meniscectomy?

OBJECTIVES The objective of this study was to evaluate the effects of fabella-tibial suture (FTS) on long-term outcome in dogs with cranial cruciate ligament (CCL) insufficiency and concurrent medial meniscal tear (MMT) that were managed by an open, caudal pole medial meniscectomy (CPMM). METHODS A retrospective review was performed of the clinical records of dogs treated for CCL insufficiency with concurrent MMT by open CPMM, with or without the non-random addition of a nylon FTS according to surgeon preference, during the period of 2001 to 2004. The Bristol Osteoarthritis in Dogs questionnaire was modified for owner assessment of outcome using a visual analogue scale based on several criteria: level of activity, disability, severity of lameness and frequency of lameness before and after surgery. RESULTS Completed questionnaires from 31 dog owners were received. A FTS was used after CPMM in 22 dogs (FTS group), but in nine dogs (control group) only a CPMM was performed. The median time to follow up was longer in the FTS group (25 months) than the control group (16 months) (P=0.03). There were not any significant differences between the two groups before and after surgery for the following: disability, activity, frequency of lameness, severity of lameness, ability to climb stairs and ability to sit down. CLINICAL SIGNIFICANCE The placement of a FTS following stifle joint arthrotomy and CPMM in dogs with CCL deficiency and concurrent MMT may not be a significant factor affecting the ultimate surgical outcome, although our study is limited by the non-randomised study design.

Interleukin-2 and interferon-gamma mRNA expression in canine anal furunculosis lesions and the effect of ciclosporin therapy.

German Shepherd Dogs have an increased incidence of anal furunculosis (AF), which is a disease characterised by inflammation and ulceration of the perianal tissues. Ciclosporin, an immunosuppressive drug, has been successfully used to treat AF, suggesting that the pathogenesis of disease is likely to have an immune-mediated component. Previous research has shown that the cytokine mRNA profile in AF lesions is consistent with T cell-mediated inflammation. The aims of the current study were to quantify IL-2 and IFNgamma mRNA expression in AF biopsies taken before and after treatment with ciclosporin and to compare cytokine expression with lesion severity. Twenty-two dogs with AF were recruited into the study and lesional biopsies were taken prior to ciclosporin therapy. Lesion severity was graded using a visual analogue scale. All dogs were evaluated after 4 weeks of ciclosporin therapy and, in 10 dogs with persistent disease, residual lesions were resected. RNA was extracted from AF-lesional tissue and control perianal tissue samples (n=10), which was used as the template for RT-PCR. Analysis of IL-2 and IFNgamma mRNA expression was performed using real-time PCR. IL-2 and IFNgamma mRNA was consistently detected in pre-treatment AF biopsies and, when quantified, this was significantly increased compared to control tissue (P<0.05). However, no correlation was seen between lesion severity and pre-treatment cytokine mRNA expression. In the ten paired pre- and post-treatment samples, IL-2 mRNA expression was significantly reduced in residual disease tissue following ciclosporin therapy (P=0.013). Treatment with ciclosporin seemed to result in decreased expression of IFNgamma mRNA in AF lesions but this was not statistically significant. In six of the 10 dogs with persistent disease, T cell cytokine mRNA could still be detected in the tissues, suggesting that there was inadequate immunosuppression. The absence of a correlation between T cell cytokine expression and the severity of disease suggests that tissue destruction observed in AF might be a consequence of other inflammatory mediators or downstream effects of T cell activation.

Airway injury associated with cervical bite wounds in dogs and cats: 56 cases

OBJECTIVE To investigate the frequency of airway injury and damage to other vital structures associated with cervical bite wounds in dogs and cats and the implications for management and outcome. METHODS A retrospective search of electronic patient records was used to identify dogs and cats suffering cervical bite wounds that were presented to a large multidisciplinary veterinary hospital over a four year period. RESULTS Complete records were available for 55 animals, with one animal suffering two separate injuries. Fourteen animals (25%) had injuries to vital structures, including airway injury in nine (17%) which was surgically confirmed and treated in six (11%). Airway injuries were associated with either subcutaneous or mediastinal emphysema in all affected animals. Other structures injured included the jugular vein, pharynx, oesophagus and spine. Airway injuries were treated with primary repair in five animals and a fasciomuscular patch in one. Temporary tracheostomy was performed in three animals. Median duration of hospitalisation was one day (0-19) with 53 animals (54 cases) (96%) surviving to discharge. Long-term follow-up (16-114 months) revealed that 43 of 49 animals were alive with six that died due to unrelated reasons. CLINICAL SIGNIFICANCE Cervical bite wounds are associated with significant injury to vital structures. Up to 17% of animals may have injury to their airway. Identification and treatment of airway injury is vital and was associated with an excellent outcome in six animals.

Attenuation of congenital portosystemic shunt reduces inflammation in dogs

Liver disease is a major cause of morbidity and mortality. One of the most significant complications in patients with liver disease is the development of neurological disturbances, termed hepatic encephalopathy. The pathogenesis of hepatic encephalopathy is incompletely understood, which has resulted in the development of a wide range of experimental models. Congenital portosystemic shunt is one of the most common congenital disorders diagnosed in client owned dogs. Our recent studies have demonstrated that the pathophysiology of canine hepatic encephalopathy is very similar to human hepatic encephalopathy, which provides strong support for the use of dogs with a congenital portosystemic shunt as a naturally occurring model of human hepatic encephalopathy. Specifically, we have demonstrated an important role for ammonia and inflammation in the development of hepatic encephalopathy in dogs with a congenital portosystemic shunt. Despite the apparent importance of inflammation in driving hepatic encephalopathy in dogs, it is unclear whether inflammation resolves following the successful treatment of liver disease. We hypothesized that haematological and biochemical evidence of inflammation, as gauged by neutrophil, lymphocyte and monocyte concentrations together with C-reactive protein concentrations, would decrease following successful treatment of congenital portosystemic shunts in dogs. One hundred and forty dogs with a congenital portosystemic shunt were enrolled into the study. We found that the proportion of dogs with a monocyte concentration above the reference range was significantly greater in dogs with hepatic encephalopathy at time of initial diagnosis. Importantly, neutrophil and monocyte concentrations significantly decreased following surgical congenital portosystemic shunt attenuation. We also found a significant decrease in C-reactive protein concentrations following surgical attenuation of congenital portosystemic shunts. Our study demonstrates that haematological and biochemical indices of inflammation reduce following successful treatment of the underlying liver disorder.

Arteriovenous Haemangioma in Two Dogs and a Cat

Haemangiomas are benign vascular tumours and several types can be distinguished based on microscopical features. Capillary and cavernous haemangiomas are most commonly reported in man and domestic animals. Arteriovenous haemangiomas are rare variants in man and herein we describe this subtype in two dogs and one cat. One dog and the cat presented with a cutaneous vascular lesion, the other dog with a bleeding mass in the tongue. Surgically excised masses comprised non-encapsulated proliferations of variably sized arterial- and venous-like vessels, accompanied by clusters of capillaries and immature vascular structures in the feline cutaneous tumour and the canine lingual neoplasm. All vasoformative elements had von Willebrand factor-positive endothelia enclosed by a smooth muscle actin-positive tunica media or by pericytes. The results of this study expand the range of differential diagnoses for vascular neoplasms in the dog and cat.

Duodenal Brunner's gland adenoma causing chronic small intestinal obstruction in a dog

An eight-year-old, neutered, female English springer spaniel was presented with a 14-month history of vomiting, marked weight loss and lethargy, all of which were non-responsive to medical therapy. Abdominal radiographs and ultrasonography showed an intraluminal soft tissue mass extending from the pyloric antrum to the proximal duodenum. Two spherical masses both approximately 8 cm in diameter were removed via a duodenotomy. Histopathological examination showed the first mass to be a trichobezoar and the aboral mass to be a Brunners gland adenoma. Surgery resulted in a complete resolution of the clinical signs.