UNIVERSITY OF SURREY

FARM ANIMAL PATHOLOGY AND DISEASE SURVEILLANCE SERVICE

Spring 2018 NEWSLETTER

Welcome to the fifth newsletter from the Veterinary Pathology Centre (VPC) at the University of Surrey.

Our reduced disposal costs for adult cattle (over 12 months of age) submitted and accepted under the APHA surveillance scheme, with a price saving of £100, only has two months to go.

We have a 48 hour window in place to help ensure the quality of the post-mortem examination - meaning that we are unlikely to accept any submissions that have been dead longer than 48hours. If a carcase is severely autolysed (48+ hours), gross lesions are difficult to identify andfurther testing (e.g. histology and bacteriology) may give inconclusive results. Please encourageyour clients to keep the carcass cool, away from scavengers and call to submit as soon aspossible. This is especially relevant for adult cattle during periods of warm weather, as theydecompose quickly.

The Surveillance Team would like to thank everyone who has participated in the Farm Animal Surveillance Service survey. Your input will greatly help us improve our service. If you have not received an invitation to take part, but are interested, please let us know.

Finally, you may have seen our recent Twitter campaign. Do you recognise this?:

Interactive PRRS dashboard now available on-line

An interactive dashboard focused on GB diagnoses of porcine reproductive and respiratory syndrome (PRRS) has been developed by the Surveillance Intelligence Unit at APHA with the Pig Expert Group.

The dashboard is available on this link: https://public.tableau.com/profile/siu.apha#!/vizhome/Porcinereproductiveandrespiratorysyndrome/PRRS

Updated APHA collection service link: To check if you are in an area where free collection is available, follow this link: http://apha.defra.gov.uk/postcode/pme.asp

For more information, please visit: http://www.surreyvetpathology.com/pathology-services/surveillance-services and look at the Surveillance Post Mortem prices.

Please do not hesitate to contact us if you would like to provide feedback or have any questions about using our service. It is important that the responsible veterinary surgeon calls us to discuss a case before submission, to ensure that it is eligible for a surveillance post-mortem examination. Eligible cases are heavily subsidised by the APHA and do not incur additional fees for routine diagnostic tests.

We look forward to working with you all.

EVENTS:

17 May 2018: Veterinary Pathology Showcase event Please register your attendance for the event on the Eventbrite page here

2 July 2018: Microbiology Society Focused Meeting on Emerging Zoonoses and AMR: A Global Threat For more details please visit: microbiologysociety.org/focused-meeting-surrey

28-29 Sept 18: British Society of Veterinary Pathology (BSVP) Autumn MeetingApplied ruminant pathology: Disease investigation, diagnosis and surveillance For more details please visit: http://www.bsvp.org

Dr Pernille Jorgensen, CandVetMed MRCVS. Surveillance Lead Farm Animal Pathology and Disease Surveillance Officer

Dr Chris Palgrave, BSc(Hons) BVM&S PhD FRCPath FHEA MRCVS Lead Pathologist: Farm Animal Pathology and Disease Surveillance Deputy Director, Surrey Veterinary Pathology Centre

INTERESTING CASES:

CATTLE

Sporadic lymphosarcoma was diagnosed in a fourteen-year old Highland cow, who had presented with clinical symptoms of inappetence, recumbency and diarrhoea for a couple of days prior to euthanasia. The gross findings consisted of icterus, severe dehydration and the presence of a 5.9 kg mass around the base of the heart and the cranial lung lobes, with formation of strong adhesions between the organs and the tumour (figure 1). Histology confirmed the diagnosis; it is suspected that the tumour may have originated from the thymus or the mediastinal lymph nodes. Based on the microscopic lesions and the position of the tumour at the heart base, as a precaution a PCR was performed on the tumour tissue to rule out Enzootic Bovine Leukosis (EBL), which is a notifiable, exotic disease to the United Kingdom. The result was negative.

A diagnosis of chronic cholangiohepatitis due to Fasciola hepatica was also made in the same case, as obvious fibrosis and calcification of the bile duct walls was seen, in addition to the presence of adult flukes within the bile ducts and gall bladder.

Figure 1: Large lymphosarcoma placed near the base of the heart.

Septicaemia and abortion due to Salmonella Newport was diagnosed in a premature limousin-cross calf, originating from a suckler herd of 55 animals. Five other cases of abortion, stillbirth and weakly born calves had occurred within a fortnight, and the dams were noticed to be lethargic prior to calving, and had retained foetal membranes. The main gross findings consisted of a large amount (roughly two litres) of yellow, thick, foul-smelling peritoneal fluid, containing fibrin, and a generalised icterus (figure 2). In addition, severe hypertrophy of the right ventricle was identified, with a ratio between left and right ventricular free wall of 1.5:1, compared to the ideal ration of 3:1. Salmonella enterica serovar Newport was isolated from the lung, liver and peritoneal fluid. There are few reported cases of Salmonella Newport in cattle, and outbreaks in beef cattle appear to be particularly rare. High mortality of both cows and calves has been reported however, and the subspecies is considered a zoonosis.

Figure 2. Generalised jaundice and suppurative peritonitis.

SMALL RUMINANTS

Ovine Pulmonary Adenocarcinoma (OPA/Jaagsiekte) was diagnosed in a five-year old pregnant ewe with clinical symptoms of laboured breathing for about 24 hours prior to death and chronic weight loss. The affected tissue consisted of multifocal to coalescing areas of consolidation of the pulmonary parenchyma, which was grey, firm and fleshy and occasionally wet on the cut surface (figure 3). The tissue sank when placed in formalin. This contagious lung tumour is caused by infection with Jaagsiekte sheep retrovirus (JSRV), which results in a progressive replacement of normal lung parenchyma with tumour tissue. The disease is highly infectious and invariable fatal.

Figure 3. Affected areas of lung are firm, fleshy, grey and severely consolidated.

Another form of neoplasia was diagnosed in a six-year old ewe with clinical symptoms of weight loss and weakness one month prior to expected lambing. A post-mortem examination identified multifocal serosal implantation metastases along a nearly two metre section of jejunum, which was covered in fibrin (figure 4). A diagnosis of small intestinal adenocarcinoma with local transcoelomic spread was made microscopically. This is the most frequently reported type of neoplasm in sheep, and is often seen in older animals, with a clinical presentation of ill-thrift, initially. Predisposing factors of this condition have not been established, although cases are most commonly seen in animals grazing pastures with high levels of bracken. Exposure to herbicides has also been associated with intestinal adenocarcinoma in sheep, while no associations with infectious agents have been described. The condition has been reported to have a low incidence in flocks.

Figure 4. Section of jejunum with serosa implantation metastases.

Enterotoxaemia associated with Clostridium perfringens Type D (Pulpy Kidney Disease) was diagnosed as a cause of sudden death in a four-year old, male pet goat. Gross pathology identified a large fibrin clot within the pericardial sac (figure 5), which is considered almost pathognomonic for pulpy kidney disease in sheep, but not a common feature in goats, where the gross pathology predominantly consists of haemorrhagic enterocolitis. The diagnosis was confirmed by isolation of Epsilon toxin within the small intestinal contents. Parasitic gastro-enteritis (PGE) was also diagnosed, based on the presence of roundworms within the intestinal tract.

It is not uncommon for goats to develop enterotoxaemia and PGE despite vaccination and regular worming, as the immune system of goats is notoriously poor, compared to other ruminants, hence specific consideration to correct dosage and administration of anthelmintics should apply.

Figure 5. Fibrin clot within the pericardial sac.

Concurrent Pulpy Kidney Disease (clostridial enterotoxaemia) and Listeria monocytogenes infection was diagnosed in a seven-week old lamb that presented with clinical symptoms of nasal discharge, bloating, seizuring and death within 24 hours. Six other lambs on farm had died within a few days whilst out on pasture. The main gross findings on post-mortem examination included diffuse, bilateral congestion of the lungs, congestion of the liver and petechia within the epicardium. These changes, although nonspecific, can be suggestive of enterotoxaemia associated with Clostridium perfringens Type D infection. Detection of Epsilon toxin from the small intestinal contents confirmed a diagnosis of Pulpy Kidney Disease. The microscopic changes seen within the brain were not characteristic of enterotoxaemia, however multifocal microabscessation did indicate encephalitic listeriosis. Listeria monocytogenes was subsequently isolated from the brain both in direct and enrichment culture.

Outbreaks of encephalitis associated with Listeria monocytogenes in young lambs have been reported; these are characterised by a rapid course of disease and possible death within 24-48 hours after the onset of clinical symptoms. The point of entry for the bacterium in this case was suspected to be the gingiva, as inflammation associated with eruption of the temporary premolars was noticed on gross examination. The lamb had not been fed silage, but a large amount of grass was present in the forestomaches and abomasum, which suggests that close-grazing and soil ingestion was the source of Listeria.

PIGS

Enterotoxaemic colibacillosis (Oedema Disease) was diagnosed in a five-month finisher pig with a history of ataxia and weakness prior to death. The pig was the third animal to die on a smallholding with ten animals. A gross diagnosis was made based on identification of subtle oedema of the eyelids, mesocolon (figure 6a), stomach (figure 6b) and heart-base. Dry faeces was present in the colon and rectum, and fibrin was seen covering the small and large intestines and within the pericardial sac (figure 5). Isolation of a heavy pure growth of haemolytic Escherichia coli, serotype E4 from the faeces and small intestines, in addition to identification of verocytotoxigenic E. coli on multiplex PCR, confirmed the diagnosis. Oedema Disease is most commonly seen one to four weeks after weaning and is associated with a change in diet, in combination with the stress of weaning, which causes the bacteria to multiply and elaborate toxins.

Figure 6a. Subtle oedema of mesocolon.

Figure 6b. Cross section of stomach. Marked oedema of the submucosa noticed.

POULTRY

Four Sussex-cross pet-hens had died within a 1-2 days, some of them with symptoms of hypersalivation and recumbency prior to death. A gross presentation of severe chronic diffuse fibrinous and purulent peritonitis/coelomitis, highly suggestive of Egg Yolk Peritonitis associated with a possible secondary E. coli infection was identified (figure 7). A granulomatous enteritis and peritonitis/coelomitis was diagnosed microscopically, which is a feature of colibacillosis. The main differential diagnosis is such cases is peritoneal carcinomatosis, however this could not be ruled out due to advanced autolysis. A mixed growth including a heavy growth of non-haemolytic coliforms was isolated from the carcass, which may support an assumption of secondary E. coli infection, however this could also be due to post-mortem opportunistic growth.

Typical Egg Yolk Peritonitis is caused by free yolk within the coelomic cavity which provokes a severe foreign-body type inflammatory response and peritonitis. Secondary infection with opportunistic bacteria such as E. coli, may also occur in some cases. The disease is therefore not considered infectious as such. Risk factors for Egg Yolk Peritonitis include anything that will cause damage to the vitelline membrane, such as trauma, bacterial septicaemia or systemic viral infections and rupture.

Figure 8. Severe chronic diffuse fibrinous and purulent peritonitis/coelomitis.

FARM ANIMAL PATHOLOGY AND DISEASE SURVEILLANCE TEAM

VPC Director: Prof. Roberto La Ragione

Pathologists/Surveillance Officers: Dr. Pernille Jorgensen (Service Lead) Dr. Chris Palgrave Dr. Barbara Bacci Dr. David Harwood Dr. Javier Salguero Dr. Alex Stoll Dr. Ana Resendes

Epidemiologists/Consultants: Prof. Alex Cook Pete Sewell Dan Cooper

Surveillance Project Manager: Julia Gerhold

VPC Administrator: Louise Ryan

Receptionist: Sue Grover-Smith

Technical Services Manager: Jon Cooper

Post-mortem Facilities Manager: Tom Hussey

Technical Staff: Ian Freeman, Kat Gowan, Emily Tubb, Mike Chaplin, Keith Hiley, Alice Robinson Pathology Laboratory Manager: Abbe Martyn

Histology Technical Staff: Duncan Grainger, Lucia Lozano White

Business Development Manager: Rachel Hargreaves

SURREY VETERINARY PATHOLOGY CENTRE

Surrey Veterinary Pathology Centre (left) and the main post-mortem room (right)

HOW TO FIND US

If using a Sat Nav, please follow postcode: GU2 7YW and do NOT turn left at the traffic lights after leaving the A3 http://www.surreyvetpathology.com