Small Animal News editor, Harriet Woodhall, brings us an article on the Pet Blood Bank, a fantastically important and lifesaving service.
Pet Blood Bank
Harriet Woodhall (Vet News Small Animal News Editor)
The Pet Blood Bank is a UK charity that supplies blood products to veterinary professionals for canine blood transfusions and has recently hit its 5000th donor in its seventh year as a charity.
Like human blood donations, there are certain criteria that dogs need to meet to ensure that donated blood is safe for a transfusion patient and not contaminated. The donor should: weigh more than 25kg, be aged between one and eight years old, have a good temperament, be up to date with vaccinations, never have traveled abroad, be fit and healthy and not be on any medication.
When a blood donation is made, the dog also needs to be blood typed so that any transfusions made are using the correct type. If given an unmatched type, the immune system will recognise the new cells as foreign and prematurely destroy them, which could lead to other complications. What causes the body to recognise foreign or self red blood cells is whether they have aminosaccharide molecules on the red blood cell membranes. As well as the presence/absence of these molecules, there are also very small differences in their structure, giving them antigenic properties.
A canine donor is normally classified as DEA (Dog Erythrocyte Antigen) 1.1 negative or positive, but the other major antigens are 1.2, 3, 4, 5, 6 and 7. DEA 1.1 negative patients should only receive 1.1 negative, whereas patients that are DEA 1.1 positive can receive both 1.1 negative and 1.1 positive. However, due to the lack of DEA 1.1 negative blood, it is always recommended that 1.1 positives receive 1.1 positive, so that supplies of 1.1 negative are preserved. The dog’s blood is screened to check Packed Red Cell Volume (PCV) and Total Solids (TS) before donation. The donors are also micro-chipped so that all blood can be traced, and have annual haematology and biochemistry screens. Once all criteria and tests are met then the dog is suggested to donate blood three to four times a year.
There are a range of blood products available:
Packed Red Blood Cells (PRBC)
Fresh Frozen Plasma (FFP)
Frozen Plasma (FP)
Fresh Whole Blood (FWB)
Stored Whole Blood (SWB)
Blood is taken from the jugular vein in the dog’s neck and put into a collection bag containing anti-coagulants. Once blood is collected from a donor, it is transported to a processing centre and is kept at 20 degrees Centigrade while travelling. The blood is then inspected and logged with a reference number for tracking purposes. Under sterile conditions, the tubing and needle are removed, blood is weighed and then centrifuged (spun at 3800 revolutions per minute) for 15 minutes to allow the red blood cells to separate from the plasma. The plasma and red blood cells are then stored separately and in special conditions to increase shelf life: plasma is stored in a minus eighty degrees Centigrade freezer, once frozen it can then be transferred into a minus thirty four degrees Centigrade freezer where it can be stored for up to five years. Red Blood Cells can only be stored for up to six weeks and are kept at four degrees Centigrade in specialist fridges.
Choosing which blood product to use depends on the reason for transfusion. For example, several diseases causing anaemia would require PRBC whereas conditions such as thrombocytopaenia (platelet deficiency) would need FWB. Some conditions could receive several suitable products but there are often superior products that are favoured if more than one option is available.
At present, only canine blood products are available from the bank. Feline patients that need transfusion can only receive fresh whole blood from emergency donors.
Rabies & The Pet Travel Scheme
Harriet Woodhall (Vet News Small Animal News Editor)
Rabies has been frequently in the news over the past couple of months due to increasing concerns that it could enter the UK and due to the presence of World Rabies Day on 28th September. There have been several cases of rabies in the Netherlands and other EU countries recently that have led to increased Government pressure to review UK quarantine laws that were previously relaxed to save pet owners money.
Rabies is a fatal disease that can potentially affect all mammals, even humans. Due to the variable incubation period and ranging characteristics, it is often difficult to diagnose and predict the spread of the disease. Rabies has a wide range of clinical signs; meaning it has to be confirmed in a laboratory; however typical signs include sudden behavioural changes and progressive paralysis leading to death, if without treatment. The disease is mainly transmitted via saliva from a bite of an infected animal; dogs being the source of 99% of human rabies deaths.
Under the Pet Travel Scheme (PETS) dogs, cats and ferrets are allowed to enter the UK without being put in quarantine, provided they have a microchip, rabies vaccination 21 days before travelling and a pet passport; dogs also need tapeworm treatment. If the requirements are not met, the animal is then put into quarantine on arrival into the UK. Only once the requirements of the PETS scheme are met can the animal be released.
A blood test and a wait of 6 months following vaccination was previously needed to enter the UK from the EU or approved countries; this was relaxed in January 2012: blood tests are no longer needed and the wait before entering is now only 21 days. The relaxed wait could be seen as a risk, seeing as the rabies incubation period is so variable and can often be longer than 21 days.
One of the biggest concerns is the increasing numbers of smuggled dogs and puppies entering the UK with forged passports, often without vaccination or vaccination at a too young age. It is thought that since regulation changes, people are less concerned about being caught due to the shorter quarantine time. This is a particularly big problem when the dog’s origin is unknown, as rabies is still endemic in parts of the world. Many vets are now suggesting that quarantine regulations are not strict enough, and are warning of the increased risk of rabies entering the UK. BVA President, Robin Hargreaves also stated that this increase and the case in the Netherlands should “be a serious wake-up call to potential pet owners who must always ask about the animal’s background and ask to see it with its mother”.
Government officials state that the risk of rabies entering the UK is still very low, but several animal welfare charities are still concerned that they are putting their staff at risk, now suggesting that staff themselves are vaccinated against the disease.
Hormone Implants for Pet Ferrets with Adrenal Disease
Charlotte Hitch (Vet News Exotics Editor)
Hyperadrenocorticism is arguably one of the most serious and prevalent diseases in pet ferrets in the USA and United Kingdom. There is a particularly high rate of incidence in neutered individuals; studies show that 50-75% of neutered ferrets develop the condition at some point in their lives. Although the prognoses may differ depending on how early in its development intervention occurs, the condition can potentially be life threatening in some cases if inflamed tissue causes anuria. The animal is then unable to remove waste and toxins from its body through urination.
Neutering the animal is considered to be one of the main causes of the onset of the disease, aside from excessive artificial light exposure and genetic predisposition. In the endocrine system, hormones work antagonistically against each other, and the presence of high levels of one hormone in the blood can stimulate the release of a different hormone to counteract the effects of the first. After neutering, there is no negative feedback from the gonads to the pituitary gland, so the pituitary gland continually releases a hormone called Gonadotrophin Releasing Hormone (GnRH) which in turn stimulates the overproduction of gonadotrophins (sex steroids) from the adrenal glands, situated beside each kidney.
One hormone produced in great quantities is Luteinizing Hormone (LH), which stimulates ovulation. The gonads are no longer present to respond to high blood LH levels, so negative feedback does not occur and the levels continue to rise in an unregulated manner. Hyperplasia occurs in the adrenal cortices, and this can lead to adenoma or carcinoma formation.
The main symptoms of the disease include severe alopecia, pruritus (itchiness), polydipsia (excessive drinking), aggressive behaviour, swollen or enlarged vulva/prostate tissue, and muscular atrophy. Adrenocortical hyperplasia may cause malignant tumours to develop; in this case the condition is often life threatening.
Current treatment options include surgery to remove the affected gland, inhibition of the release of GnRH using melatonin, and desensitisation of the pituitary gland using Lupron Depot injections, again stopping the production of GnRH. Unfortunately, surgery has limitations in that only the left gland can be removed safely because ferrets with both adrenal glands absent are likely to develop Addison’s disease, and the right gland is extremely close to the vena cava. Melatonin and Lupron only work to relieve the symptoms; they do not remove the tumour (although Lupron may shrink it).
Recently, subcutaneous deslorelin implants manufactured by Virbac have been legally marketed in the UK. Over the period of about 8 months, the implant releases hormones which antagonise the release of GnRHs, removing the stimulus for the overproduction of sex hormones by the adrenal glands. This treatment is multifunctional because not only can it be used to reduce the effects or prevent the onset of adrenal disease, but it can even be used as an alternative to neutering, saving the ferret the pain and risk associated with surgery. The implants are not yet approved in the USA, but with further research they may have great potential in the treatment of this highly prevalent condition.
Immune Mediated Haemolytic Anaemia (IMHA) in Dogs
Harriet Woodhall (Vet News Small Animal Editor)
In a normal, healthy dog red blood cells (RBCs) live around 4 months and are then destroyed by the immune system to be replaced. In a dog with IMHA the immune system destroys RBCs prematurely as if they were a foreign virus or infection; this means they cannot be replaced at the same rate.
There are two forms of IMHA: primary (idiopathic) and secondary. In primary IMHA the body produces anti-erythrocyte (RBC) antibodies which bind to surface antigens on RBCs and lead to their destruction. Although the exact cause is unknown, there are some breeds more susceptible: Cocker Spaniels, Poodles, Old English Sheepdogs and Irish Setters. Secondary IMHA also results in antibody attachment to RBCs but occurs when the patient is exposed to a drug, toxin or has an underlying neoplastic or infectious disease.
Common symptoms include anaemia, lethargy, tachypnea (increased respiratory rate), anorexia, weakness and vomiting. Most of the symptoms arise from reduced RBCs and lack of oxygen delivery to tissues.
Diagnosis can be particularly difficult and expensive with the primary purpose to demonstrate that antibodies are attached to the surface of the RBCs. A physical exam and history need to be taken along various laboratory tests such as a Complete Blood Count and a Saline Auto-Agglutination (to evaluate the clumping of cells which arise from antibody attachment). Although the most useful starting point is Saline Auto-Agglutination it can often take a lot of laboratory tests to fully diagnose the disease.
At present there is no cure for IMHA, current treatments aim to improve RBC concentration and to stabilise the patient.
Most emergency cases need blood transfusions which try to increase haemoglobin concentrations in the blood. Transfusion products can be whole blood, red blood cells or haemoglobin concentrates with the main goal to improve oxygen delivery to the tissues. While most dogs don’t have naturally occurring alloantibodies, blood typing is still important with the universally accepted blood donor being DEA (dog erythrocyte antigen) 1.1 negative.
Another treatment method is immunosuppressive therapy using corticosteroids to slow down RBC destruction and RBC phagocytosis as well as reducing antibody production.
It is thought that T regulatory cells play a part in autoimmune diseases when there are a reduced number or they have functional defects. Therefore there is the suggestion that replacing the T-regulatory cells with those grown from stem cells would be an effective treatment for the disease. Although this seems feasible a lot more research needs to be done to ensure effective delivery of the cells and whether the treatment is practical and safe.
We have a NEW member of the Vet News Editorial Team in the form of Harriet Woodhall, who has taken on the mantle of covering articles of interest in the small animal sphere. So, big welcome to you Harriet and thank you for your first article, which this month is on Canine Diabetes Mellitus.
But before we start….. an intro 🙂
I’m 17 and will be applying for Vet School in September. I live just outside Cambridge along with two (adorable) black Labradors and some chickens. Aside from researching and studying I’m very interested in the conservation of wild species and enjoy playing piano.
Canine Diabetes Mellitus
Harriet Woodhall (Vet News Small Animal Editor)
It is estimated that approximately 1 in 500 dogs develop diabetes and although there are certain breeds that are more susceptible, (Golden Retrievers, Keeshond and Poodles being just a few), all breeds of dog can be affected, most often when middle aged or older.
The disease is caused by inadequate/complete lack of insulin from islet cells in the pancreas. Insulin is the hormone responsible for controlling the concentrations of glucose in the blood – this is achieved by preventing glucose production in the liver and making sure that excess glucose is put into storage.
Common signs of diabetes mellitus include polyuria (production of too much dilute urine), polydipsia (excessive thirst) and polyphagia (losing weight despite increase appetite). Cataracts are also often seen in diabetic dogs due to increased glucose levels. Along with the clinical signs, hyperglycaemia (high blood sugar levels) and glycosuria (sugar in the urine) are often enough of an indication for diagnosis. Diabetes is best diagnosed early, as when left untreated serious secondary complications can arise such as diabetes ketoacidosis.
Like humans, dogs can have insulin therapy, most having two insulin injections a day. Bitches should be spayed, as the hormone progesterone produced by the ovaries has a negative influence on insulin. In combination with injections it is recommended to have diet, exercise and weight control. For dogs, a diet high in fibre and complex carbohydrates is suggested, so glucose is more easily controlled and released more slowly.
Researchers in Barcelona have recently been able to cure diabetes in Beagles with gene therapy. The Beagles were given two extra genes which work together to reduce hyperglycaemia. One gene produces the insulin needed and the other produces an enzyme called Glucokinase, responsible for regulating the uptake amount of glucose from the blood. The genes are transferred by adeno-associated vectors, also a new technology. Using a non-pathogenic virus, the genes can be injected into the hind legs of the dog in a single session.
As the first successful study of its kind, there will need to be more evidence using a larger test sample. However, it seems the future use of gene therapy could provide a more effective and practical method of controlling diabetes in dogs
Callejas D, Mann CJ, Ayuso E, Lage R, Grifoll I, Roca C, Andaluz A, Ruiz-de Gopegui R, Montane J, Munoz S, Ferre T, Haurigot V, Zhou S, Ruberte J, Mingozzi F, High K, Garcia F, Bosch F. Treatment of Diabetes and Long-term Survival Following Insulin and Glucokinase Gene Therapy.
New PCR Test available for bovine mycoplasma
Bovine mycoplasma is a bacterial infection that is responsible for several diseases in the cow. Although it mainly causes respiratory disease, it can also be responsible for abortions, mastitis and arthritis. Clearly, this leads to huge economical losses within the dairy industry: €500 million per year in the European dairy industry alone. The disease is a tricky one to conquer. It is hard to diagnose due to its inconsistent gene expression and varying response to treatment. M. bovis is also very similar to another bacterium, m. agalactiae, varying by only 8 nucleotides in its genetic makeup. It is also incredibly slow and difficult to culture, and treatment with antibiotics is not cost-effective. Therefore, the main means of controlling the disease lies with prevention. Recently, a new PCR test for m. bovis has become available, making the future for the control of the disease much brighter.
PCR testing is a method of copying fragments of DNA, which can then be used to locate the presence of a pathogen in an organism. Firstly, the DNA strand is separated using a thermocycler at a high temperature. The mixture is then cooled and sequences of nucleotides that have complementary bases to each end of the DNA fragment that needs to be copied, called ‘primers’ are attached. These provide a starting sequence for the copying of DNA. Then, the temperature is increased to around 72°C to provide the optimum temperature for DNA polymerase to work at. This adds other nucleotides to the DNA sequence, thereby copying the DNA. In a short amount of time, several copies of the DNA can be made. These can then be compared to the DNA of the bacterium to see whether it is present. It is a rapid and efficient method of pin pointing the disease – this particular test takes only 2.5 hours before the results are ready. “The improved sensitivity of this new test means that veterinarians will be able to monitor dairy herds for sub-clinical infection using samples from the bulk tank,” said Eric Sellal, Head of Animal Health EMEA at Life Technologies.The scientists have improved upon the previous test by locating a new target gene on the mycoplasma bovis genome, which is clearer to locate.
Hopefully, this new test will provide veterinarians with a tool for quickly locating this pathogen and preventing its rapid spread throughout the herd.
AQA Biology A2 textbook – Glen Toole and Susan Toole (Nelson Thornes)
Scientists believe that SBV may affect wild animals
Emma Plowright (Vet News Farm Animal Editor)
Scientists in Europe are concerned that wild animals may be acting as a ‘reservoir’ for the midge-bourne Schmallenberg virus (SBV) which has been detected on nearly 1,000 farms in England and Wales.
A team from the Universite de Liege in Belgium who have been monitoring the disease in wildlife have noted that it can also affect roe deer and red deer. One member of the team has called for “specific surveillance of wild animals for SBV”
If pregnant ewes are infected, the virus causes deformities and neurological abnormalities in. An expert at the University of Nottingham has stated that although we can confirm that deer get the disease, it is not currently known how they will be affected. The placental structure of a deer differs from that of cows and sheep meaning that, at present, it is not known if the virus can cross the placenta.
SBV has a huge economic impact and figures from the University of Nottingham show that some farms are suffering up to 30% losses; this can have a devastating effect on farmers’ livelihoods. Professor Trevor Drew of the UK government’s Animal Health and Veterinary Laboratories Agency spoke recently of the difficulties in trying to control the disease: it is midge Bourne and “It is just impossible to control midges across an area the size of Europe”
Alick Simmons, the UK’s chief veterinary officer, has stated that he believes the disease “will either through vaccination or through natural spread become less of a problem over time”, adding that several vaccines are currently being developed. He also pointed out that some areas which were affected by the virus last year were not affected so severely this year.
Continuing on from my regular Nerdy Vet feature on a clinically relevant topic, this month I was reminded of an all too common condition that we see in small animal practice and which can be easily prevented. Unfortunately it is a problem that many pet owners are simply unaware exists and a lot find out for the first time when their pet is admitted to hospital for investigation and subsequent treatment, all costing a fair amount of money and anxiety for all concerned. What is it we’re talking about? Well, this month our vet lesson is on….
This literally translates as ‘pus’ (pyo) and ‘uterus’ (metra) so no prizes for guessing that it refers to an infection of the uterus, with the vast majority of cases we see in practice being in non-spayed bitches shortly after the end of their most recent season. The reason for this classic timing is to do with the changes in uterine environment and conditions associated with the hormones of oestrus, resulting in a really nice, nutrient rich environment for bacteria to proliferate with less hassle from the immune system. This doesn’t necessarily lead to trouble assuming that the body’s defences can keep any infection in check and clear it up once the animal finishes oestrus and all things return to ‘normal.’ It is highly likely that many dogs have bacteria present in their uterus around the time of heat, simply as a result of their cervix being wide open to the world, but thanks to the wonders of immunity and the fact that bad luck tends to occur far less than some pessimists might have us believe, they get on with life and no problems arise.
There are two main types of pyometra that we might consider. The first is what we refer to as an ‘open’ pyo, in which the cervix is still open and pus can, and does, freely drain from the uterus. This one is generally much easier to a) diagnose (they have pus dribbling from their bits!) and b) treat, as they will often respond well to antibiotics with the safety of being able to monitor the improvement (pus clears up generally equals dog better). I would then recommend neutering that bitch at the next suitable opportunity, most likely several weeks later once everything has involuted and it becomes a ‘safer’ surgical procedure to perform, as our standard advice on spay timing.
The bad boy scenario is the second type, which we refer to as a ‘closed’ pyo. Imagine having an infection raging on behind closed doors, in this case a closed cervix. The uterus, being an organ of finite capacity, fills with pus and expands. The result is an inflamed, pus filled, very unhappy uterus, with the bitch eventually showing signs of general illness. Some will present with signs much sooner than others, with some bitches apparently being as hard as nails and looking fine clinically in spite of having an abdomen full of pus-filled uterus! The bacterial toxins that are produced by the infection can enter the blood and lead to a host of clinical signs, including an increased thirst, malaise and lethargy, vomiting, diarrhoea, and generally just being off their food and out of sorts.
The normal presentation is a bitch who has been generally off colour for a little while and who has a history of being in season within the past few weeks, although pyometra can occur at any time so should always be considered a differential in un-neutered females. They may have clear aberations in their clinical parameters, such as congested mucus membranes, or tachycardia (higher than normal heart rate), and will often be reported as drinking more than normal, off their food and possibly even nauseous, all fairly non-specific signs of illness. If suspected, then a blood test, including haematology to check white cell count, is a good idea, as is an ultrasound scan. Classic cases will show a marked elevation in white cell numbers, especially neutrophils, which are like the riot police of the immune system, being the first to pile on in to areas of infection to start the fight. A scan will usually, but not always, especially if it is a ‘small’ pyo, show fluid filled loops of uterus, with a floculent (think static on your TV) appearance, as opposed to a nice dark liquid appearance. Such changes would be enough to advise rapid treatment.
In some cases, where there is considered to be no risk of uterine rupture, and where the cervix is open, allowing pus to freely drain out of the body, medical management can be considered as an initial measure, the aim being to bring the infection under control and reduce the size of all structures involved in preparation for surgery to neuter as per a normal elective procedure. This usually takes a couple of weeks and can be a very nice way of managing the patient. The cost is possibly a little less than immediate, emergency surgery, although when you factor in the revisits, medication used and the possibility of the animal not responding as planned, then the costs are often very similar. Most cases of confirmed pyometra are still taken to surgery immediately, in order to remove the infected uterus and ovaries (ovariohysterectomy) and thus solve the problem straightaway. These patients would be given antibiotics, anti-inflammatories and intra-venous fluid therapy both prior to, during, and if necessary, after surgery, and would almost certainly go home with antibiotics and anti-inflammatories. Most, if managed sensibly by their owners at home, recover very well and within a week are the bright, happy, appetant animals that their owners remembered having. It is a very satisfying surgery to perform as you know that what you’re doing is making an immediate and clear difference to the chances of that patient surviving and recovering.
In terms of the surgery itself, the approach is the same as for a standard spay, with a midline, ventra (belly) approach to the abdomen and careful incision into the abdominal cavity. The risk with these compared to standard neutering ops is that the uterus is often very distended and may be punctured on your approach into the abdomen itself, which would be a disaster. Once safely in the abdomen, it is usually very easy to find the uterus (look for the big, fluid filled loops of ‘sausages’). Thus starts the very careful task of exteriorising the loops and finding the ovarian pedicles (the ligamental and vascular attachments of the uterus and ovaries to the kidneys on both sides. The risk is that the turgid, fragile uterus could rupture at any moment, spilling it’s toxic contents into your patient and effectively signing their death warrant, so we handle the tissues as if they were made of rice paper, with gentle, smooth movements and avoiding anything that could result in them being torn or punctured. Having an assistant can be extremely helpful in such situations. The ovarian pedicles are clamped and ligated (I personally prefer to transfix, which means I anchor my ligatures in the pedicle itself) and the ovary and uterus separated from it’s attachment, allowing the safely ligated pedicle to be returned to the abdomen. The same is repeated on the other side, followed by the careful clamping and ligating of the cervix. Once free of all attachments my aim is to get that horrid pus filled uterus as far away from my surgical site as I can, but doing so very carefully as it can still rupture and spoil the party at the last minute. Once it’s out of the danger zone, then assuming we have no bleeding or other issues, the abdomen is closed as per usual and the patient recovered.
Neutering. Simple. Unless owners are planning to breed their bitches then there really is little good reason why they should need to remain entire. Ask any owner who was hesitant about spaying their bitch before they had a pyo what their thoughts on neutering are afterwards, then I would confidently guess that the vast majority would be strong advocates of neutering. Yes it can be risky surgery but then developing pyometra, or mammary cancer for that matter, is no walk in the park either and both can be prevented by the application of veterinary knowledge and skill.
So, there you have it. Pyometra is this month’s Vet Lesson and is one you are bound to see at some point during your time on work experience.