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.

Brachycephalic (short-muzzled) dogs are increasingly popular pets worldwide, with marked increases in registrations of breeds such as the Pug and French Bulldog over the past decade in the UK. Despite their popularity, many brachycephalic breeds are affected by an early-onset, lifelong respiratory disorder, brachycephalic obstructive airway syndrome (BOAS). This disorder arises due to a mismatch in the proportions of the skull and the soft tissues held within the nose and pharynx, resulting in obstruction of the airway during respiration. Increased airway resistance encourages secondary changes such as eversion of the laryngeal saccules and collapse of the larynx. Clinical signs of BOAS are often early onset and chronic, including dyspnea, exercise intolerance, heat intolerance, and abnormal and increased respiratory noise. Episodes of severe dyspnea can also occur, leading to cyanosis, syncope, and death. BOAS may have a severe impact upon the welfare of affected dogs, compromising their ability to exercise, play, eat, and sleep. Although a well-described condition, with surgical treatments for the palliation of this disorder published since the 1920s, many dogs still experience airway restrictions postsurgically and a compromised quality of life. In addition, the prevalence of this disorder does not appear to have substantially reduced in this time, and may have increased. Ultimately, strategies to improve the breeding of these dogs to prevent BOAS are required to improve brachycephalic health and welfare. Recent studies have revealed conformational risk factors associated with BOAS, such as short muzzles and thick necks, which should be discouraged to avoid perpetuating this serious disorder. Positive changes to brachycephalic health may be impeded by a perception of BOAS being "normal for the breed". This perception must be avoided by owners, breeders, and vets alike to prevent undertreatment of individuals and the perpetuation of this serious disorder to future generations of dogs.

Hepatic encephalopathy (HE) is an important cause of morbidity and mortality in patients with liver disease. The pathogenesis of he is incompletely understood although ammonia and inflammatory cytokines have been implicated as key mediators. To facilitate further mechanistic understanding of the pathogenesis of HE, a large number of animal models have been developed which often involve the surgical creation of an anastomosis between the hepatic portal vein and the caudal vena cava. One of the most common congenital abnormalities in dogs is a congenital portosystemic shunt (cpss), which closely mimics these surgical experimental models of HE. Dogs with a cPSS often have clinical signs which mimic clinical signs observed in humans with HE. Our hypothesis is that the pathogenesis of HE in dogs with a cPSS is similar to humans with HE. The aim of the study was to measure a range of clinical, haematological and biochemical parameters, which have been linked to the development of HE in humans, in dogs with a cPSS and a known HE grade. One hundred and twenty dogs with a cPSS were included in the study and multiple regression analysis of clinical, haematological and biochemical variables revealed that plasma ammonia concentrations and systemic inflammatory response syndrome scores predicted the presence of HE. Our findings further support the notion that the pathogenesis of canine and human HE share many similarities and indicate that dogs with cPSS may be an informative spontaneous model of human HE. Further investigations on dogs with cPSS may allow studies on HE to be undertaken without creating surgical models of HE thereby allowing the number of large animals used in animal experimentation to be reduced.

In a survey of uk veterinary practitioners, 96 per cent indicated that they performed ovariohysterectomy on cats via flank laparatomy rather than a midline coeliotomy. At a veterinary teaching hospital 32 cats were spayed by the midline approach and 34 by the flank approach, by undergraduate students under the continuous supervision of a veterinary surgeon. The duration of each part of the procedures was recorded and information was obtained from the students, the supervisors and the owners of the cats by means of questionnaires. The total duration of the surgery and the students' assessment of the difficulty of the surgery were not significantly different between the two groups. The time taken from the skin incision to entering the peritoneum was significantly longer with the flank approach, but finding the uterus took significantly longer with the midline approach. There was a high incidence of wound complications, in the form of swelling, redness or discharges, but the only statistically significant difference between the groups was a greater incidence of discharges in the cats spayed via the flank (five cases) than in the cats spayed via the midline (one case).

Practical relevance Although a relatively uncommon condition, the investigation, diagnosis and initial medical management of feline congenital portosystemic shunts is often undertaken within general practice. Early recognition and appropriate treatment are important to ensure a good outcome.Clinical challenges Clinical signs associated with CPSSs in cats are extremely variable and can be intermittent. Signs can affect a variety of organ systems including the nervous system, and gastrointestinal and urinary tracts. Thus, the differential diagnosis list may be very long and a CPSS may not be suspected initially. More specific diagnostic tests and diagnostic imaging are indicated but may not be 100% accurate and may not be readily available to the general practitioner.Audience This review highlights challenging aspects of the investigation and management of CPSSs for the practising veterinarian, but is also relevant to postgraduate students and provides a practical summary for specialists.Patient group In practice, domestic shorthairs make up the majority of cats with CPSSs. However, Siamese, Persian and Himalayan cats may be more commonly affected than other purebreeds. While cats with CPSSs are typically under 6 months old, the condition is seen in mature animals, which may not have exhibited clinical signs for months or years.Evidence base Despite several retrospective studies of cats with CPSSs, the evidence base for management of the condition remains limited.