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Dogs

A new differential for canine pneumothorax

6 Dec, 16 | by gmills

By Cameron Knight

An article recently published in Veterinary Record Case Reports describes a case of fatal pneumothorax in a dog secondary to malformation of a single lung lobe. Within the published literature, most canine cases with a similar presentation are diagnosed as congenital lobar emphysema (CLE). However, in this particular dog, CLE was ruled out by a panel of veterinary and human paediatric pathologists. Histological lesions closely resembled congenital pulmonary airway malformation (CPAM), a disease that is well recognised in children, but that has never been reported previously in any veterinary species. This report proposes that CPAM be considered in the differential diagnosis for canine spontaneous pneumothorax, and clarifies the distinction between CLE and CPAM.

The case describes an eight-month-old female boxer dog with progressive respiratory distress and no previous history of disease, trauma or toxin exposure. Pneumothorax was diagnosed and repeat thoracentesis and oxygen supplementation were performed for three days. CT confirmed bilateral pneumothorax and showed variably sized bullae in the right middle lung lobe, leading to a presumptive diagnosis of CLE.

During anaesthetic induction for lung lobectomy, the dog developed cardiopulmonary arrest and died. A postmortem examination was performed, which confirmed severe bilateral pneumothorax with atelectasis of all lung lobes, and revealed a small, pale and flaccid right middle lobe with several ruptured bullae (Fig 1). The primary bronchus supplying this lobe was flattened, with a slit-like, rather than circular lumen. In addition, the right subclavian artery had an aberrant origin from the left subclavian artery, rather than from the brachiocephalic trunk.

Fig 1: Right lung of a dog that died from spontaneous pneumothorax. (A) The right pleural cavity, with the cranial (RCr), middle (RMd) and caudal (RCd) lobes of the right lung labelled. The caudal lobe has been reflected dorsally to better expose the middle lobe. All lobes are severely atelectatic. In addition, the middle lobe is pale and flaccid. (B) The right middle lung lobe at higher magnification. Several collapsed bullae (yellow arrowheads) are present along its ventral and ventrocaudal margins

Histological sections of the right middle lobe were difficult to recognise as lung tissue. They consisted predominantly of thick fibrovascular trabecular networks outlining collapsed, empty cavities lined by a simple cuboidal to simple squamous epithelium. All other lung lobes in the dog had normal histological architecture.

A diagnosis of CLE was ruled out histologically. CLE requires overinflated alveoli or hyperplastic alveoli, whereas the affected lobe in this dog lacked alveoli. Instead, after consultation with seven human paediatric pathologists, a diagnosis of CPAM-like disease was reached. The term CPAM refers to a spectrum of human airway malformations characterised by abnormal development of various portions of the tracheobronchial tree. CPAMs are well recognised and relatively common in people, and are characterised by multiple irregular pulmonary cystic structures lined by varying types of epithelium. The distinction between CLE and CPAM in humans is not merely academic. Importantly, CPAM may progress to malignant neoplasia, while CLE does not. Lobectomy is generally indicated for CPAM lesions, while CLE may resolve spontaneously and can often be managed conservatively.

While CPAM-like disease has never been reported in the veterinary literature, there are 11 reports of CLE in dogs. After reviewing these, it is possible that some reported canine cases of CLE may, in fact, represent CPAM-like disease. This case highlights the necessity for histological distinction between these two diseases, and describes a novel condition that may result in spontaneous pneumothorax in dogs.

More details, images and discussion about this case can be found here: http://vetrecordcasereports.bmj.com/content/4/2/e000378.full.

Dog gets a raw deal

21 Jul, 15 | by gmills

An article recently published in Veterinary Record Case Reports describes a case of small intestinal segmental volvulus in a dog secondary to dietary obstruction. Small intestinal volvulus is an infrequently encountered condition in small animal practice. Within the published literature, there are notable contrasts in the clinical history and examination findings described as well as the success of the surgical intervention itself. This cases serves to propose both a cause for the volvulus and also describe its successful management.

The case describes a four-year-old golden retriever that had been vomiting intermittently and had been lethargic for a few days. The owners described the diet which the dog was being fed as consisting of a chicken bones and raw food (BARF) diet along with boiled potatoes and pasta. There was no history of foreign bodies having been consumed.

On clinical examination, there was an area of mid-abdominal intestinal thickening within the abdomen, but no discrete foreign body was palpated. Biochemistry, electrolyte and haematology blood samples were unremarkable, while abdominal radiographs were consistent with an intestinal foreign body (Fig 1).

At exploratory coeliotomy, segmental small intestinal volvulus was identified, and successfully excised by enterectomy without previous derotation. The patient made a smooth recovery from anaesthesia and surgery. Upon dissection of the excised portion of intestine, bones that were anatomically typical of those contained in chicken legs were found.

BARF diets have been recently increasing in popularity among dog owners. This is not currently mirrored by the profession where the vast majority are still cautious on their use especially in regard to the food hygiene and nutritional imbalance risks. This having been said, there are increasing numbers of the profession now considering whether BARF diets can be used in dogs, and if so how they can be nutritionally balanced.

This case demonstrates that intestinal volvulus, which is often considered to have an acute onset, may have a more delayed presentation, and still be successfully surgically managed. Additionally, it demonstrates that intestinal obstruction with secondary volvulus can occur due to dietary obstruction when a dog is fed a BARF diet.

More details, images and discussion about this case can be found here

Fig 1: (a and b) Right lateral and dorsoventral abdominal radiographs showed gastric as well as intestinal dilation, increasing the suspicion of gastrointestinal obstruction

Fig 1: (a and b) Right lateral and dorsoventral abdominal radiographs showed gastric as well as intestinal dilation, increasing the suspicion of gastrointestinal obstruction

Shock and awn: two unusual cases of grass seed ingestion in dogs

4 Dec, 14 | by Assistant Editor

 

It is well known that the common or garden grass seed is the root of many problems in veterinary practice. Two recent articles published in Veterinary Record Case Reports (here and here) describe less common, but serious consequences following the ingestion of a grass awn by dogs.

Case 1

A 15-month-old female mixed-breed hunting dog weighing 16.5 kg was referred with a three-day history of change in bark, progressively worsening dyspnoea, decreased appetite and dullness. The onset of clinical signs was shortly after hunting. On admission, the bitch showed abduction of the forelimbs and inspiratory dyspnoea. Thoracic auscultation revealed muffled heart and dull lung sounds in the caudodorsal part of the thorax, as well as crackles on the caudal lung lobes.

Three litres of air was aspirated from the chest and supplementary oxygen was delivered via a facemask. Thoracic radiography showed elevation of the heart from the sternum and increased thoracic lucency due to the presence of pleural air. The edges of the caudal lung lobes were retracted from the chest wall and an area of soft tissue opacity was evident in the area of the caudal vena cava, the caudal border of the heart and the cupula of the diaphragm.

 

F1.large

Radiograph showing elevation of the heart from the sternum, the presence of pleural air and an area of soft tissue opacity between the caudal vena cava, the caudal border of the heart and the cupula of the diaphragm

 

Soon after radiography the dog developed severe dyspnoea and cyanosis. Thoracentesis was repeated and 2500 cm3 of air was removed while the syringe plunger was forced back, indicating tension pneumothorax.

Tension pneumothorax is an emergency condition in which a flap of tissue acts as a one-way valve so that air entering the pleural space during inspiration cannot be expelled during expiration. This is a rapidly deteriorating state that must be recognised and treated quickly, otherwise it may prove fatal.

 

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The arrow shows a grass awn adhering to the parietal pleura

 

An emergency exploratory thoracotomy was performed and a grass awn was found adherent to the parietal pleura of the right 10th intercostal space and a 2 mm rupture, covered with fibrin, was identified in the ventral surface of the right caudal lung lobe. A partial lung lobectomy was performed. The dog recovered uneventfully, and was discharged two days after surgery. On re-examination two and six months later, the dog was normal and thoracic radiography revealed no abnormalities.

Case 2

In another case, a six-month-old male neutered crossbred dog presented with a two-week history of pain on opening the mouth and intermittent lethargy. There was also a history of mild blepharospasm of the right eye and pyrexia. On referral, ophthalmic examination revealed mild exophthalmia of the right eye, with a small amount of third eyelid protrusion and decreased retropulsion of the globe. There was marked pain on opening the mouth and palpation over the right temporal region of the skull.

Ocular ultrasound showed increased echogenicity of the tissue within the retrobulbar space and marked diffuse signal on Doppler examination. MRI of the brain and orbit revealed dependent fluid in the right frontal sinus and nasal cavity with mucosal thickening suggesting local rhinitis and sinusitis. There was hyperintense retrobulbar tissue thickening along the lateral aspect of the orbital lamella of the frontal bone, and evidence of regional myositis.

 

F2.large (1)

MRI images of the brain and orbit. These images show a marked degree of contrast enhancement in the retrobulbar tissue, periorbital tissue and frontal sinus mucosa

 

Right exophthalmos was present, likely due to diffuse retrobulbar swelling. Despite this, orbital structures were preserved.

Exploratory craniectomy was performed. And three grass seeds and approximately 4 ml of yellow, high viscosity fluid were removed from the surgical site, which was then lavaged with warm saline. Postoperatively the dog was maintained on intravenous amoxicillin and clavulanic acid before being discharged on oral medication.

Four months after the cessation of antibiotic therapy the dog was re-examined and the owner reported no problems when the dog opened its mouth. The dog was also reported to have returned to a normal life and general physical, neurological and ophthalmic examinations were unremarkable.

More details, images and discussion about these cases can be found here and here.

Simply bred: could global exchange of cryopreserved canine semen be preventing genetic isolation of populations?

20 Nov, 14 | by Assistant Editor

 

New research suggests that the global exchange of frozen semen from dogs of registered breeds may be reducing genetic divergence between geographically distant dog populations. The study, published in Veterinary Record, looked at similarities between groups of dogs in South Africa and the UK. 

 

According to rules set out by the Kennel Club in the UK (KCUK) and the Kennel Union of Southern Africa (KUSA), for a dog to be registered as a recognised breed, it must have five generations of ancestors of the same breed. Regulations such as this create a genetic barrier, limiting the number of genes that cross between breeds and reducing genetic diversity within breeds.

In a study published last year, Mellanby and others found that, in the UK, rottweilers, boxers and German shepherd dogs had the highest levels of inbreeding of the breeds studied. Labrador retrievers and border collies had lower levels of inbreeding (although genetic analysis showed that inbreeding was still present in these breeds). They also assessed a population of Jack Russell terriers, which are not recognised as a breed by KCUK, although they are by KUSA. Perhaps unsurprisingly, this non KCUK-registered population had the highest levels of genetic diversity in the study.

 

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Jack Russell terriers are not recognised as a breed by the UK Kennel Club, but they are by the Kennel Union of South Africa

While each individual breed is genetically distinct, it was not known whether dogs of a particular breed in one country differed genetically from those in another. If boxer breeders in the UK tended only to breed from UK stock, it would be expected that this population would begin to genetically diverge from boxers in other countries. In other words, is a collie from Cape Town similar to one from Carlisle? Do the genes of a dobermann in Durban resemble those of one in Durham? These were some of the questions that an international team of researchers from institutions in the UK and South Africa sought to answer in a recent study published in Veterinary Record.

‘We had found that different dog breeds had different levels of genetic variation,’ says Kim Summers, one of the authors of the study. ‘We also knew that there were restrictions about importing animals into some countries, so we wanted to find out whether this meant that dogs of the same breed in two countries had started to diverge genetically’.

DNA material was obtained from German shepherd dogs, labrador retrievers and Jack Russell terriers that were brought to the University of Pretoria veterinary clinic in South Africa. The DNA was analysed and compared with that of DNA from UK dogs that had been analysed in a previous study.

The study yielded several interesting results. First, a coincidental finding was that many dogs thought to be purebred were actually of mixed breed origins. While these misclassified dogs had the physical traits of the breed they were classified as, in-depth genetic analysis showed that almost a third (four out of 14) of the South African labrador retrievers and one of 26 German shepherd dogs actually had mixed breed ancestry. Several of the South African dogs studied were also found to have had one parent from the registered breed and another that was a mixed breed

‘Most studies in the past have used only pedigree dogs registered with a breed association,’ said Prof Summers. ‘We were interested in how well the breed could be identified by looking at the dog, because correct identification of breed is important for knowing which genetic variants might be important in diseases the dog may have.’

Perhaps even more surprisingly, population analysis revealed that within each breed, dogs were remarkably similar regardless of the country.

 

GILL_189

A boxer dog. Boxers are a registered breed in both the UK and Southern Africa

 

‘We found that our genetic markers could not distinguish dogs of one breed based on their country of origin,’ Prof Summers explains. ‘So there was a genetic signature for labrador retrievers that was the same in South Africa as in the UK.’ 

The fact that dogs in the UK were found to be similar to dogs of the same breed half way across the world is puzzling. This would indicate that there is a reasonable amount of genetic admixture between dogs of the same breed. One way that this could occur, the authors suggest, is through the use of cryopreserved canine semen for artificial insemination. This has been available to dog breeders for some 50 years and it is now possible for semen to be frozen and transported long distances before being used in breeding. This worldwide exchange of genetic material could be preventing genetic isolation from occurring within breeds, despite vast geographical distances.

‘Breed associations and breeders are very concerned with the health of their breed’, said Prof Summers. ‘Encouraging the use of a wide range of sires and reducing matings between relatives will maximise genetic diversity and ensure that breeds are similar and healthy across the world.’

 

Researchers investigate what really goes on in small animal consultations

5 Nov, 14 | by Assistant Editor

 

New open access research published in Veterinary Record indicates that almost half of veterinary consultations last longer than the 10 minutes allocated and that preventive medicine consultations last just as long as consultations for a specific health problem. The results raise issues to do with practice management, as well as the importance of educating veterinary students about comorbidities. 

 

Consultations are a major part of small animal practice, with small animal vets often meeting a large number of clients and patients each day. Generally speaking, 10 minutes is allocated for each consultation, but the amount of time required to address all of the client’s concerns can often exceed 10 minutes. Furthermore, consultations are often complex interactions in which a wide range of potential health problems are discussed.

In human medicine, large amounts of research has been conducted into the nitty gritty of how consultations work and the types of issues that are discussed. This has shown that more lengthy consultations tend to lead to more issues being discussed and better detection and management of certain conditions. However, until now, veterinary consultations have been less well understood.

A group of researchers at the University of Nottingham recently sought to fill these knowledge gaps by conducting some in-depth research into small animal consultations in the UK. They wanted not only to better understand how long consultations last and what happens during a consultation, but also to develop a tool that would make it easy to analyse veterinary consultations in depth. Their results are reported in two articles recently published in Veterinary Record (found here and here), both of which are open access.

Natalie Robinson, one of the authors of the studies, explains the idea behind them.

‘When the Centre for Evidence-based Veterinary Medicine was first set up at the University of Nottingham, one of our first questions was “What should our research priorities be?”’, she said. ‘We needed to make sure our research was relevant to first-opinion practitioners, so examining the veterinary caseload to determine what practitioners see and do every day was the first logical step. By examining consultations in greater depth, we can start to identify the important decision-making points during the consultation. This will allow us to generate new evidence which can support veterinary decision-making and hopefully lead to improved patient care.’

Eight small animal practices in England and Scotland took part in the study. The team observed a large number of consultations in detail, and recorded what they saw using a specially developed tool.

 

176_7631

The research showed that small animal consultations often ran over the allocated 10 minutes

 

Timings

One of the studies assessed how long consultations tended to last. The researchers timed 182 consultations involving 203 animals in two of the participating practices in England.

They found that there was a huge range in the length of consultations. The shortest consultation observed lasted for just 51 seconds, while the longest lasted for 36 minutes and 45 seconds. Almost half (48 per cent) of consultations exceeded the 10 minutes allocated. Perhaps unsurprisingly, consultations in which more problems were discussed, or which involved more patients, tended to last longer.

‘One of the things that surprised us is that preventive medicine consultations lasted just as long as consultations for a specific health problem’, said Dr Robinson. ‘Preventive medicine consultations are often seen as “quick and easy” but the results would suggest that this is not necessarily the case. In fact it would appear that preventive medicine consultations may be even more complex than other types of consultations, with even more problems discussed, and so are an important part of the healthcare of our pets.’

 

Looking at consultations in more detail

In another part of the study, a total of 1720 consultations (involving 1901 patients) were recorded and analysed. The results make interesting reading.

The first key finding was that a total of 4486 problems were discussed for the 1901 patients, an average of 2.4 problems per patient. In almost two-thirds of consultations, more than one problem was discussed. The highest number of problems discussed in one session was eight.

‘Interestingly, fewer problems were discussed for rabbits than for cats or dogs,’ said Dr Robinson. ‘While there could be a range of reasons for this finding, it could be that vets and owners are less familiar with identifying health problems in this species. Previous work within our group has suggested that vets feel there is less information available for rabbits than for dogs or cats, so it could be that rabbit medicine is an important area for the generation of new evidence.’ The previous study she refers to was published in Veterinary Record earlier this year.

 

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In almost two-thirds of consultations, more than one problem was discussed. The highest number of problems discussed in one session was eight.

 

More health problems were also discussed in consultations involving older animals, while when younger animals were presented, preventive medicine was more likely to be discussed.

While the results answer some questions, they also raise others. For example, if consultation length varies so widely, should vets begin to offer different types of appointments? The authors suggest that practices could set up geriatric clinics specifically aimed at older animals in which appointments are longer, ensuring enough time for all problems to be discussed.

They also note that the findings could have implications for veterinary education, as they show that comorbidities are common and consultations can be complex.

‘We need to make sure that training in consultation skills adequately prepares veterinary undergraduates for the realities of first-opinion practice,’ said Dr Robinson. ‘The findings suggest that first-opinion consultations often involve dealing with multiple problems and comorbidities within a single consultation, meaning the decision-making process is often complex.’

‘Ultimately, we need more evidence to support decision-making in patients with comorbidities, which will benefit not only undergraduate education, but also the wider veterinary profession and the patients they treat.’

 

Searching for a needle in a…

19 Aug, 14 | by Assistant Editor

 

Veterinary Record Case Reports publishes high quality cases in all disciplines, so that clinicians and researchers can easily find important information on both common and rare conditions. Here, Alastair MacMillan, Editor of the online-only journal, highlights an interesting case involving an inquisitive labrador.

An eight-month-old female labrador retriever presented with progressive cervical hyperaesthesia after being seen coughing close to a broken sewing kit two weeks previously. She had cervical hyperaesthesia and mild proprioceptive deficits in the right thoracic and pelvic limbs. CT imaging of the neck showed a thin metallic foreign body going in a ventrodorsal direction through the vertebral canal at the atlanto-occipital junction.

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CT showing a sewing needle going in a ventrodorsal direction through the vertebral canal at the atlanto-occipital junction 

Once the needle was located, it was easily grasped using Mosquito forceps, and removed in its entirety. Marked clinical improvement was observed the day after surgery and the owner reported a complete recovery of the patient, with return to normal activities in due course.

F3.large3D reconstruction showing the needle in the atlanto-occipital junction (arrow)

Reports of foreign bodies in the vertebral canal are rare in human and veterinary medicine. Although ingestion of foreign bodies is common in companion animals, sewing needles without an associated thread rarely cause a problem, as they either fail to reach the stomach, or pass through the intestinal tract uneventfully. Although brain abscessation associated with a penetrating needle has been previously reported, this is the first report of a sewing needle penetrating the vertebral canal and being surgically removed with complete clinical recovery of the patient.

To read the full report, click here.

Bark more likely than bite? Sterilisation programmes in India

9 May, 13 | by sarahbrown

 

Human dog bite injuries are a major public health problem, particularly where there are large populations of free-roaming or street dogs. In countries with endemic rabies, the bites of animals are the main means of transmission of this disease and dogs are accountable for 91.5 per cent of all bite wounds in India. Bites by dogs were also responsible for 96.2 per cent of human rabies cases in India. But despite the public health importance of dog bites, there has been little research into the causes or means of prevention.

In India, control of free-roaming dog populations has been attempted using animal birth control (ABC) programmes. Jack Reece and co-authors have previously reported that the ABC approach has been successful in controlling both the street dog population and rabies. The objective of their current study, recently published in Veterinary Record, was to determine if a relationship exists between the reproductive behaviour of dogs and human dog bites.1 Reece and his co-workers at Help in Suffering, Jaipur, had noted that the dispersal of pups of street dog litters from the dam occurred between 90 and 120 days after whelping. Anecdotal evidence from animal control personnel in the city indicated that bitches would often try to protect their two-to-three-month-old pups by biting personnel.

Canine reproduction has been found to be seasonal in Jaipur, with peak whelping activity in November. Humans being bitten by animals, as reported by the main government hospital in Jaipur, showed a seasonal trend with peaks in January and June; approximately 10 weeks after the seasonal peak of street dog breeding.

The authors found that, following the start of an ABC programme in 1996, the percentage total of the female dog population that had been spayed, rose quickly and has remained at between 70 and 80 per cent since 2003. They also observed that the number of human animal bite cases has declined since then, despite a rapidly expanding human population.

Children represent the biggest proportion of bite patients in India

They conclude that, whereas sterilisation could not have led to an immediate halt in the growth of the dog population, the rapid increase in the percentage of spayed females may have prevented the further increase in bite frequency, if dog bites are indeed primarily due to bitches trying to protect their puppies.

They add that the results of their study suggests that, in addition to the benefits of rabies control, ABC programmes may have an effect on the numbers of human animal bite cases that far exceed the effects of reducing the dog population to the same level by indiscriminate culling.

Jack Reece explained, ‘The ABC programme at Help in Suffering (HIS) was set up to gather data about the effects of such programmes. HIS is an animal welfare charity, not a veterinary research institute, which is why my colleagues and I not only sterilise and vaccinate large numbers of street dogs (3199 sterilisations last year; 81 in the last week), but also monitor the effects and record data on many aspects of the work, including the street dog population and biology. Animal welfare is clearly a driving force for veterinary surgeons and animal welfare charities such as HIS, but it is unlikely to influence political leaders or bureaucrats. It’s for this reason that the HIS team have tried, where possible, to show human health benefits to ABC work; by publishing such benefits in peer-reviewed international veterinary journals, we hope that these decision makers may change their policies from ineffective culling and removal to more effective humane dog population control. As ordinary practicing veterinary surgeons, rather than academic researchers, it is pleasing to be able to suggest that our veterinary work has a direct and measurable affect on the health and the safety of the public – an example perhaps of the currently fashionable ‘One Health’ concept.

Reece, J. F., Chawla, S. K. & Hilby, A. R. (2013) Decline in human dog bite cases during a street dog sterilisation programme in Jaipur, India. Veterinary Record doi: 10.1136/vr.101079

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