Management of the Patient with Canine Parvovirus Enteritis

PROCEEDINGS OF THE NEW ZEALAND VETERINARY NURSING ASSOCIATION ANNUAL CONFERENCE 2015 5 Management of the Patient with Canine Parvovirus Enteritis Philip R Judge BVSc MVS PG Cert Vet Stud MACVSc (Veterinary Emergency and Critical Care; Medicine of Dogs) Senior Lecturer: Veterinary Emergency and Critical Care, James Cook University, Australia Director: Vet Education Pty Ltd (www.veteducation.net) All documents are copyright to Vet Education Pty Ltd. Permission has been granted for inclusion in the NZVNA conference proceedings. Canine Parvovirus is a highly contagious virus that aects typically causes symptoms of disease in tissue with rapidly dogs, resulting in severe gastrointestinal disease and dividing cells such as the gastrointestinal tract and bone occasionally cardiac disease. e virus itself is what is termed marrow: “non-enveloped”, and is made up of viral DNA. Canine - Cells of the intestines replicate rapidly on an ongoing parvovirus infection is a serious viral infection in dogs, basis, and are therefore aected by (and destroyed by) and as mentioned above, is highly contagious, being readily parvovirus infection, which results in diarrhoea and transmitted from one dog to another through contact with vomiting. infected faeces. - Cells of the bone marrow of young dogs are replicating, producing red and white blood cells. Infection with ere are some important facts about the virus itself that parvovirus aects production of white blood cells, and underpin some important aspects of patient management… can result in profound leukopaenia in infected patients. • Canine parvovirus is a stable virus that can survive for up - In young dogs that are born to unvaccinated parents, to ve to seven months in the environment. is means, and that are infected within the rst two weeks of life, susceptible dogs can contract the virus simply by contacting the muscles of the heart may be aected as they replicate and ingesting virus in a contaminated environment. in the rst two weeks of life, causing myocarditis. As • One gram of faeces from an infected, virus-shedding dog most dogs have some history of vaccination, cardiac is thought to contain enough viral material to infect over manifestation of parvovirus has become much less 10 million susceptible dogs by oral exposure! common – because maternal antibody usually provides • Canine parvovirus vaccination is very eective in protection against parvovirus infection in neonates preventing disease. However, young animals may still during the rst two weeks of life, during myocardial be at risk of contracting the disease despite vaccination, development. because antibodies in circulation from maternal colostrum • Symptoms appear when the virus infects cells within inactivate early puppy vaccinations in a number of puppies. the body. Intestinal cells become infected by day four In fact, a 12 week vaccination with a modied live canine of infection – and gastrointestinal symptoms of disease parvovirus vaccination will be inactivated by colostrum- usually appear over the subsequent two to three days. derived antibody in the puppy in approximately 8% of puppies. Vaccination protocols that stop at 12 weeks of Clinical Signs age can result in susceptible puppies. e clinical signs of canine parvovirus are usually the result • e virus initially infects the lymphoid tissue in the pharynx of intestinal and bone marrow cell destruction by the virus, before it enters the bloodstream, where it contaminates and therefore include the following: cells around the body, including the intestines, bone • Anorexia marrow and dividing cardiac cells in the very young. • Depression • Canine parvovirus replicates in dividing cells, and thus • Vomiting • Profuse haemorrhagic diarrhoea Histopathology slides from a normal myocardium (le!) and myocardium infected with canine parvovirus (right). Note the Photographs of canine parvovirus. Being non-enveloped presence of large numbers of in"ammatory cells and the loss renders the virus extremely resistant to desiccation of pink muscle tissue in the infected section. 6 PROCEEDINGS OF THE NEW ZEALAND VETERINARY NURSING ASSOCIATION ANNUAL CONFERENCE 2015 • Abdominal discomfort possible; evaluate stool characteristics. Collect faeces • Cardiovascular shock for evaluation • Dehydration g. Complete full physical examination • Pyrexia 3. Collect a Patient Data Base – for patients with diarrhoea • Infection – resulting from leukopaenia – or decreased as a presenting sign, the following samples should be white blood cell count, and disruption to the intestinal collected at admission, or shortly following admission, to mucosal barrier, which allows intestinal bacteria to gain facilitate diagnostic evaluation of the patient: access to systemic circulation a. PCV/TP • Sudden death and congestive heart failure – may result if b. Glucose myocardial damage occurs in very young patients c. Electrolyte evaluation Diagnosis d. Blood gas analysis !e diagnosis of canine parvovirus is made on the basis of e. Serum biochemistry and complete blood count clinical signs and a history of poor vaccination protocol, or f. Urinalysis lack of vaccination history, along with con"rmation using g. Faecal evaluation – smear, faecal $otation, immunologic a faecal antigen test (parvovirus “snap” tests). In addition, assessment e.g. parvovirus, giardia, clostridium because there are many other diseases that may also result perfringens; culture if required e.g. campylobacter spp., in similar clinical signs, a thorough evaluation of the patient salmonella spp. must be performed as outlined below… h. Abdominal radiography – preferably three views – right and le% lateral and ventro-dorsal recumbency views. !e diagnostic evaluation of the patient with acute Radiographic contrast studies may be carried out based gastroenteritis is critical to ensure that speci"c therapeutic on results of physical examination, blood tests, and modalities are not overlooked, and to ensure that inappropriate survey radiography. treatment is not administered to the patient. !e diagnostic i. Abdominal ultrasound evaluation usually follows the following format: A Note on Faecal Analysis 1. History – obtaining a complete and thorough history can !e diagnosis of acute infectious gastroenteritis is made aid in directing an appropriate diagnostic approach to the on the basis of history (including the health of in-contact patient. Pertinent questions to raise during history-taking animals and people); clinical examination, results of serum include: biochemistry, CBC and urinalysis, and faecal evaluation. a. Diet – current diet, any recent change, previously noted intolerances Faecal analysis should begin with faecal $otation – which will b. Behaviour of the patient - scavenging behaviour enable detection of organisms such as giardia, toxoplasma, c. Duration and progression of presenting signs and the whipworm Trichuris vulpis etc. Direct faecal smears d. Environment – does the patient have access o# the are useful for detection of intestinal parasites. A stained owners’ property etc? smear of faeces and immunological techniques can allow e. Parasite control detection of clostridium enterotoxin etc., and faecal culture f. Toxin exposure – are there herbicides, pesticides, can be useful in other infections. household products, human medications that the Staining of a faecal smear may allow detection of many patient has access to etc. organisms associated with infectious enteritis in dogs and g. Is the patient de-sexed? cats, as outlined below: h. Concurrent medical conditions i. Previous medical history 1. Wright’s Giemsa or Di# Quick stain – allows detection of a. White blood cells – the presence of neutrophils suggests 2. Physical examination – physical examination should in$ammation, commonly seen in Salmonella spp., reveal the presence of the following: campylobacter spp., or clostridium spp., and should a. Fluid de"cit – hydration status, evidence of blood prompt faecal culture to be performed volume depletion b. Bacterial morphology consistent with campylobacter b. Mentation spp., clostridium perfringens c. Abdominal evaluation c. Mononuclear cell examination – may reveal presence of i. Conformation Histoplasma spp. ii. Auscultation 2. Methylene Blue staining allows detection of d. Palpation – palpate the abdomen several times during a. Trophozoites of enteric protozoa the course of initial evaluation. Evaluate for the presence of pain; abnormal organ shape, size, or position; A Note on Faecal Elisa Tests for Parvovirus evidence of obstruction; palpation of unusual structures Enteritis e.g. tube-like thickening of intestines in intussusception !e faecal ELISA tests are very accurate, but can give etc. erroneous results on occasion – for example: e. Pain (nature, severity, location) • False positive results – where a dog does not have f. Rectal evaluation – palpate prostate or uterus if parvovirus, but tests positive for it – can occur between PROCEEDINGS OF THE NEW ZEALAND VETERINARY NURSING ASSOCIATION ANNUAL CONFERENCE 2015 7 Faecal analysis may reveal Whipworm (Trichuris) egg (le), Giardia cyst (centre) or hookworm (ancylostoma) egg (right) ve and een days following a vaccination - Hypochloraemia may be present, along with • False negative results – where a dog has parvovirus, but hypokalaemia +/- hyponatraemia does not test positive for it – can occur if a faecal sample - Urea and creatinine +/- phosphorus may be elevated is taken very early in the disease (within one to four days also of becoming infected). False negative tests should

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