UNIVERSITY OF SURREY

FARM ANIMAL PATHOLOGY AND DISEASE SURVEILLANCE SERVICE

AUTUMN 2019 NEWSLETTER

Welcome to the autumn 2019 newsletter from the University of Surrey’s Veterinary Pathology Centre (VPC) .

DISEASE FOCUS

This is a new section that will focus on the diseases identified through the Centre’s surveillance activities.

Parasite gastroenteritis (PGE)

Find out more here: http://beefandlamb.ahdb.org.uk/wp/wp-content/uploads/2016/08/BRP-Worm-control-in-sheep-manual-8-170816.pdf

This was the most common diagnosis recorded in our Centre in sheep during the summer-autumn 2019 period.

Top tips

• Focus mostly on pasture parasite load, instead of just flock treatment, thus ensuringtreatments will be effective for longer periods.

• Periodically check faecal egg counts, following worm treatment to check effectivenessof treatment and for the development of anthelmintic resistance.

PLEASE REMEMBER THAT WORMS CAN KILL!

And

ANTHELMINTIC RESISTANCE IS RISING IN ENGLAND

Fox carcasses survey – APHA needs your help

Fox carcasses are wanted in your area to help the UK national surveillance program on Echinococcus multilocularis led by the APHA. Find out more in the attached leaflet.

fox-leaflet-oct19.pdf

SERVICE UPDATES

INTERESTING CASES INVESTIGATED BY the UNIVERSITY OF SURREY

Cattle

• Portocaval thromboembolism in a dairy cow• Salmonellosis infection in a dairy cow• Verminous pneumonia in a beef cow• Nephritis, cystitis and peritonitis in a steer• A case of bracken toxicity in a beef cow

Small ruminants

• PGE-Haemonchus spp.• Pituitary abscess syndrome• Copper toxicity

Pigs

Streptococcus suis infection in post-weaned pig

Birds

• Aspergillus infection in a duck• Marek’s disease in turkeys• Mycoplasma infection in chickens

EVENTS

-20 November 2019- Sheep Health, Wealth & Production Conference, University ofSurrey

-14-15 November 2019- London Vet Show, London

We look forward to working with you all,

Dr Benedetta Amato, DVM, MRCVS, PhD Surveillance Lead Farm Animal Pathology and Disease Surveillance Officer

INTERESTING CASES CATTLE Portocaval thromboembolism in a dairy cow 4 years old Friesian cow showing milk drop and wasting. Negative for Johne’s disease. No recent vaccinations. Post-mortem examination findings The conjunctiva and mucous membranes were congested. The abdominal cavity was filled with a large amount of yellowish to brownish, ascitic fluid. There were thick layers of fibrin among the liver, the diaphragm and the prestomachs. The diaphragm showed also some haemorrhagic petechiae. The Glisson’s capsule was markedly thickened and opaque (Fig. 1). The liver was increased in volume and consistency showing enhanced reticular pattern. Randomly spaced abscesses 2.0 to 4.0 cm in size were widely distributed into the liver parenchyma involving also the bile ducts that appeared thickened. A large septic thrombus was attached to the wall of the caudal vena cava suggesting necro-suppurative, chronic-active phlebitis (Fig.2). There was a mild to severe increase in thickness of the gallbladder wall and the content was scant. Lungs were variable in consistency due to the presence of intraparenchymal abscesses variable in size that are compatible with a metastatic, suppurative pneumonia (Fig.3). The heart showed haemorrhagic petechiae on the epicardium surface, embolic thrombi were also observed in the heart's chambers and the pericardium was thickened. The spleen was dark in colour. The post-mortem findings were suggestive of a caudal vena caval thrombosis and it was confirmed histologically. Caudal vena caval thrombosis in cattle is most commonly caused by liver abscesses. Liver abscesses are common in feedlot and dairy cattle fed rations that predispose to rumenitis. High-grain diets leads to the release and accumulation of short-chain fatty acids in the rumen. Accumulation of short-chain fatty acids can cause proliferation of rumen papillae to increase absorption surface, subsequently leading to a thickening of the rumen mucosa. Concentrate feeds are also responsible of the prolonged decline of the ruminal pH that can lead to subacute, lactic, ruminal acidosis predisposing to rumenitis. However past chronic fasciolosis may have contributed to the fibrotic changes of the liver.

Fig.1: Cow, liver, fibrosis.

Fig.2: Cow, vena cava, septic thrombus.

Fig.3: Cow, lungs, multiple abscesses. Salmonellosis infection in a dairy cow Dairy cow with post calving metritis showing the following clinical symptoms: fever, anorexia, reduced milk production, black diarrhoea. The dam was treated with Synulox for two days and with 20 ml of penicillin and streptomycin, before death. Post-mortem examination findings The conjunctiva and mucous membranes were slightly congested. The liver was increased in volume. The gallbladder content was dark green to black and thick. The spleen was dark in colour. The ruminal and omasal contents were dry. In particular, the omasum was moderately distended and impacted. The abomasum contained brown watery ingesta mixed with small stones, sand and undigested cereals. The jejunum and ileum were diffusely markedly congested and contained a blood-tinged content (Fig.5). The large intestinal and caecal contents were liquid. Faeces were scant and dark black in colour (melena). Urine was dark in colour and the bladder mucosa appeared slightly congested. The uterus was distended and filled with foul-smelling dark brown fluid (Fig.4). The endometrium was red-yellow and dull. The histological examination confirmed the endometritis and the systemic inflammatory reaction due to septicaemia/endotoxemia. Salmonella Typhimurium was isolated from the intestinal content, uterus, lungs and liver. Proteus spp. was isolated from the uterus. Occasionally Proteus spp. is associated with endometritis and it is responsible of the production of fetid purulent secretions. Furthermore, the presence of stones and sand could be indicative of pica due to mineral deficiency possibly associated with subclinical acidosis.

Salmonella: Serotyping

Serotype Sub Genus Serogroup S. Typhimurium I B

Phage Type Phage Type 104

Find out more in the attached leaflets and link:

salmonella investigations rumin

info-note-sal-farmers.pdf

https://www.who.int/news-room/fact-sheets/detail/salmonella-(non-typhoidal)

Fig.4: Cow, uterus, endometritis. Fig.5: Cow, small intestine, mucosal congestion.

Verminous pneumonia in a beef cow 9 months old Sussex female foaming from the mouth and wasting. Treated with antibiotics. Previous clinical signs of pneumonia in April 2019. Post-mortem examination findings There were traces of yellowish mucus around the nostrils. Haemorrhagic petechiae were observed on the subcutaneous tissue of the caudal third of the neck and the thorax. The same petechiae were also detected on the adventitia of the trachea and the epicardium. The thoracic cavity contained a small amount of clear yellow fluid. The trachea and bronchi contained a large amount of foam, yellowish mucus and several slender, threadlike, white, and 3-10 cm long nematodes grossly compatible with Dictyocaulus viviparus (Fig.6). The lung parenchyma appeared diffusely emphysematous. Air was also found in the subpleural space of the caudal lobes while the cranial lobes appeared moderately to markedly congested, consolidated and atelectatic. A focal round air-filled cavity of about 12 cm was observed in the left caudal lobe. The anatomopathological findings were suggestive of chronic verminous pneumonia with secondary bacterial infection. The histopathological examination of the lungs confirmed the gross findings observed. Lungworm larvae were identified following Baermann examination of faeces.

Fig.6: Cow, trachea, Dictyocaulus viviparus.

Nephritis, cystitis and peritonitis in a steer Steer grazed on council land with pedestrian access showing anorexia, hard abdomen, dehydration signs, foul-smelling breath, dyspnoea. Issues with urinating or passing faeces were also detected. The cow was treated with Loxicom, Betamox, Buscopan, Norfenicol, Restore, liquid paraffin. Post-mortem examination findings The abdominal cavity of the Sussex steer contained approximately 5 litres of clear yellow fluid. Several strands of fibrin extended between the liver, the omentum, the spleen, intestines, and rumen (Fig.7). The liver was pale in colour and the gallbladder appeared distended. The rumen content was moderately dry. The omasum was enlarged, and the content was dry. Furthermore, forestomachs and liver showed autolytic changes. The small and large intestines were pale. Kidneys were increased in volume and friable. The cortex was whitish to yellowish in colour with widespread haemorrhages (Fig.8). A progressive atrophy and cystic enlargement of some renal lobes was observed. The bladder was distended. The mucosa was irregularly reddened, necrotic and thickened. Some yellowish calculi up to 1 cm in diameter were observed in the bladder content together with a small quantity of blood tinged urine. The gross and histopathological findings identified a urinary insult (nephritis and cystitis) with concomitant peritonitis. Uroliths were also detected. Most reported cases occur in steers, mainly animals castrated at an early age. The dietary and environmental factors could influence the development of urolithiasis. Some predisposing factors include mineral imbalance (e.g. imbalance in the calcium to phosphorus ratio of the diet) or excessive mineral intake, lack of drinking water or water of poor quality and plants containing high levels of oxalate. The laboratory results showed mixed flora containing predominantly a very heavy growth of non-haemolytic Escherichia coli. Escherichia coli is one the most common agents involved in urinary tract infections.

Fig.7: Cow, abdominal cavity, peritonitis. Fig.8: Cow, kidneys, nephritis. A case of bracken toxicity in a beef cow Adult beef cow grazed in New Forest showing fever and treated with Ketoprofen and Pen/Strep. Post-mortem examination findings Several haemorrhagic petechiae were observed mainly in the subcutis and muscles of the left side of the animal. The left parascapular lymph nodes appeared swollen and haemorrhagic. The soft tissue around the lymph node was gelatinous and haemorrhagic. The thoracic and abdominal walls as well as the diaphragm were diffusely affected by haemorrhagic phenomena (Fig.9). The thoracic cavity contained a moderate amount of blood tinged fluid. The tracheal wall was gelatinous, yellow with haemorrhagic petechiae. Furthermore, trachea and bronchi showed a large amount of foam. Severe fibrous adhesions between lung lobes were detected. The lung parenchyma was oedematous, variable in colour with severely congested to dark haemorrhagic areas compatible with acute, fibrino-haemorrhagic interstitial lung disease. The pericardial fluid was moderately increased in volume and blood tinged. Haemorrhagic petechiae were observed on the epicardium. The abdominal cavity contained a moderate amount of blood tinged fluid. The rumen content was dry and contained a moderate amount of acorns and oak leaves. A rope and Paramphistomum larvae were also observed. The omasum was enlarged, and the content was dry. The thickness of the abomasal wall was increased. The mucosa was severely congested to haemorrhagic and showed raised, necrotic, haemorrhagic lesions. The liver was variable in colour showing yellowish to pinkish well demarcated discoloration areas. The gallbladder was markedly distended and showed haemorrhagic petechiae on the serosal surface. The uterus showed haemorrhagic petechiae as well as the foetus. Haemorrhagic petechiae were diffusely observed in the prestomachs and the small and large intestines. The intestinal content and

the faeces contained a large amount of blood. Two quarters of the mammary glands appeared increased in volume. The parenchyma was moderately congested showing some yellowish, well demarcated necrotic to purulent lesions. The content was watery, and blood tinged. The brain was moderately congested. The post mortem examination revealed systemic haemorrhages confirmed histologically. The absence of neutrophils observed in both the histological examination and a blood smear is justified by the trilineage bone marrow hypoplasia. It is likely that the cause of this condition was an acute bracken intoxication as a result of the potential exposure to the plant and the lesions observed. The identification of a moderate number of acorns and oak leaves in the rumen may have contributed to the rapid progression of the disease. Cattle can consume small quantities of acorn and oak leaves without any effect. However, they contain nephrotoxic tannins that can produce renal dysfunction.

Fig.9: Cow, thoracic cavity, hemorrhages.

SMALL RUMINANTS PGE-Haemonchus spp. 6 months old lambs in a poor condition. Recently wormed and moved to clean pasture. Post-mortem examination findings Three 6 months old lambs were submitted for post mortem examination. The three lambs showed similar pathological findings. The conjunctiva and mucous membranes were diffusely pale, white in colour. The abomasal content was fluid, dark brown and mixed with numerous hair-like worms 2-3 cm long grossly resembling Haemonchus spp (Fig.10). The abomasal mucosa was moderately to markedly congested. Melena was also detected in the gastrointestinal tract together with Moniezia spp. in the small intestine in two cases. Mesenteric lymph nodes were moderately to markedly enlarged. Two of them showed, also, lung consolidation compatible with pneumonia. All the three lambs showed severe anaemia, serous fat atrophy, poor body condition and the presence of hair-like roundworms in the abomasum. This condition is compatible with a severe Haemonchus spp. infestation and it was confirmed by laboratory results. The general condition of the animals was also compromised by the presence of Moniezia spp.

Fig.10: Sheep, abomasal content, Haemonchus spp.

Pituitary abscess syndrome Ram showing neurological signs including head tilt and ataxia. Treated with Oxytetracycline, Pen-Strep. Flock vaccinated for clostridial disease. Post-mortem examination findings A large amount of turbid cerebrospinal fluid was detected. The leptomeningeal surface appeared opaque. The brain was moderately congested and marked deposition of greenish purulent material around the sphenoid bone extending to the leptomeninges and medulla oblongata was observed (Fig.11). The gross pathology findings were suggestive of pituitary abscess syndrome. A moderate pure growth of Trueperella pyogenes was identified by the microbiological culture. This bacterium is commonly isolated in cases of suppurative meningitis in ruminants. Local bacterial invasion from a septic source or haematogenous spread of infection is the most common route of infection.

Fig.11: Sheep, skull, abscess.

Copper toxicity Adult sheep dying after showing malaise and dark urine. Recently the flock had problems of foot scald. Wormed recently with ivermectin and vaccinated with Heptavac P. Closed flock. Post-mortem examination findings A generalised jaundice involving the subcutis and inner organs was observed (Fig.12). The liver parenchyma was friable with marked diffuse tan/orange parenchymal discolouration. Kidneys were enlarged and dark grey in colour (gun metal grey). The urine was dark in colour (Fig.13).

Fig.12: Sheep, carcass, jaundice. Fig.13: Sheep, kidneys, 'Gun Metal' appearance. PIGS Streptococcus suis infection in post-weaned pig 2.5 months old gilt showing laboured breathing. Breeding sows vaccinated for Erysipelas and Parvo with access to outdoors. Post-mortem examination findings The conjunctiva and mucous membranes were red to bluish in colour as well as the cutis of the neck, thorax and, partially, abdomen cyanosis. Severe fibrous adhesions between lungs, the thoracic walls, the pericardium and the diaphragm were detected. The trachea and bronchi contained a large amount of foam. The lung parenchyma was variable in colour with a moderately congested to dark, mottled aspect involving about 60 percent of the organ (Fig.14). Abundant, yellow, clear fluid was detected into the pericardial space. The tracheobronchial lymph nodes were enlarged. The liver was variable in colour with scattered white spots 0.2-1 cm visible under the liver capsule associated to larger whitish discoloration areas (Fig.15). The consistency of the organ was increased. This condition is compatible with previous parasite migration and subsequent fibrosis (Ascaris suum). The small and large intestines were moderately congested. The brain was moderately congested.

The laboratory findings showed a pure growth of Streptococcus suis from the lungs. The histology examination reported a chronic, suppurative, eosinophilic broncho-interstitial pneumonia. No influenza or PRRS viruses were detected. The previous parasite migration has predisposed the pig to the bacterial pneumonia.

Fig.14: Pig, lungs, pneumonia. Fig.15: Pig, liver, white spots due to the parasite migration. POULTRY Aspergillus infection in a duck Lame duck. Treated with Meloxicam. Post-mortem examination findings The liver was pale and markedly enlarged. Lungs were moderately to markedly congested, partially consolidated showing multiple granulomas variable in size, white to yellow in colour and protrusive to the organ surface. The air sacs were diffusely thickened and filled with yellow to white necrotic material. Both lungs and air sacs showed a fuzzy-green appearance (Fig.16). The proventriculus and the ventriculus were empty. The pyloric sphincter of the ventriculus was obstructed by a metallic, sharp-pointed object (Fig.17). The pancreas showed a mottled appearance. Kidneys were pale in colour. The intestine was gas filled and empty. Aspergillus spp. infection was detected. In this case it was complicated by the metal foreign body that caused an obstruction.

Fig.16: Duck, air sacs, pneumonia. Granulomatous and Fig.17: Duck, gizzard, foreign body. necrotising air sacculitis. Marek’s disease in turkeys 3 months old turkeys showing lameness and poor growth rates. Vaccinated with Poulvac MG when they were 10 weeks old. Wormed with Flubendazole. Post-mortem examination findings Thoracic air sacs appeared thickened, opaque with multiple whitish lesions. Lungs showed severe congestion of pulmonary blood vessels. Increased yellow coloured fluid in pericardial sac was detected. The liver showed a mottled and pale appearance with some haemorrhagic areas and multiple whitish to yellowish circular multifocal to coalescing lesions (Fig.18). The latter were also observed in the spleen and in kidneys. Furthermore, both appeared diffusely moderately to markedly enlarged. The microbiological culture showed a very heavy pure growth of non-haemolytic Escherichia coli from the liver. The histopathological report supported the microbiological findings suggesting bacteraemia or septicaemia. However, the RT-PCR performed on the spleen was positive for vMDV. It is likely that in this occasion the bacterial involvement was secondary or terminal. Following the identification of Marek’s disease virus in the farm high standards of hygiene, all-in/all-out production and vaccination are recommended.

Fig.18: Turkey, liver, multifocal variably sized whitish nodular lesions. Mycoplasma infection in chickens Mixed laying and show chickens showing respiratory signs including sneezing and coughing. Kept indoors with outdoors pens. The same problem was detected in April in a different batch. The birds were treated with Tylan. Post-mortem examination findings The conjunctiva of the right eye appeared moderately congested. The crop was full. Lungs were slightly congested. The spleen appeared moderately enlarged. Kidneys were slightly enlarged. The RSA performed on the sera was positive for Mycoplasma gallisepticum and the most significant finding at the histopathological examination was the plasmalymphocytic sinusitis/rhinitis which is strongly suggestive of a mycoplasma infection as well. Routine infection control procedures, including good sanitation and disinfection, reduce the risk of transmission between birds. Mycoplasma gallisepticum can be inactivated by many disinfectants including 1% sodium hypochlorite, iodophors, phenolic disinfectants, peracetic acid, formaldehyde, glutaraldehyde, and ionic and non-ionic detergents. Furthermore, direct or indirect contact with potential sources of the organism should be avoided.

RELEVANT PUBLISHED PAPERS This is a new section of the newsletter created to support veterinary surgeons with their daily work. It contains a selection of at least two recently published, peer-reviewed scientific papers on relevant subjects. - Sturgess-Osborne C, Burgess S, Mitchell S, Wall R. (2019). Multiple resistance to macrocyclic lactones in the sheep scab mite Psoroptes ovis. Vet Parasitol.; 272:79-82. Abstract The astigmatid mite Psoroptes ovis (Acari: Proroptidae) causes the highly contagious and debilitating ovine disease, sheep scab. This ectoparasitic infection has a high economic and animal welfare impact on British sheep farming. Following recent work demonstrating resistance of Psoroptes mites to moxidectin, a widely used macrocyclic lactone (ML) treatment for scab, the current study compared the toxicity of three of the commonly administered macrocylic lactone therapeutic treatments (moxidectin, ivermectin and doramectin) to P.ovis from outbreak populations that had appeared unresponsive to treatment. These outbreak populations were from Wales and south west England. The data presented demonstrate that there is resistance to all three available ML compounds in populations of Psoroptes mites. However, considerable variation in response suggested that resistance alone was not responsible for the reported lack of efficacy in all of the submitted cases; lack of response in others may be associated with inappropriate treatment application or management. These data highlight the importance of the appropriate use of these compounds to manage national scab incidence at levels that are consistent with acceptable animal welfare standards, while attempting to reduce the development and spread of resistance.

- Kumssa DB, Penrose B, Bone PA, Lovatt JA, Broadley MR, Kendall NR, Ander EL. (2019). A reconnaissance survey of farmers' awareness of hypomagnesaemic tetany in UK cattle and sheep farms. PLoS One; 11;14(10). Abstract Hypomagnesaemic tetany (HypoMgT) in ruminants is a physiological disorder caused by inadequate intake or impaired absorption of magnesium (Mg) in the gut. If it is not detected and treated in time, HypoMgT can cause the death of the affected animal. A semi-structured questionnaire survey was conducted from July 2016-2017 to assess farmers' awareness of HypoMgT in cattle and sheep in the UK. The questionnaire was distributed to farmers at farm business events and agricultural shows, and through a collaborative group of independent veterinary practices to their clients. Farmers were asked about (i) the incidence of presumed HypoMgT (PHT); (ii) their strategies to treat or prevent HypoMgT; (iii) mineral tests on animals, forage and soil, and (iv) farm enterprise type. A total of 285 responses were received from 82 cattle, 157 mixed cattle and sheep, and 46 sheep farmers, of whom 39% reported HypoMgT in their livestock, affecting 1-30 animals. Treatment and/or prevention against HypoMgT was reported by 96% respondents with PHT and 79% of those without. Mineral tests on animal, forage, and soil was conducted by 24%, 53%, and 66% of the respondents, respectively, regardless of PHT. There was a highly significant association between the use of interventions to tackle HypoMgT and the incidence of PHT (p < 0.01). The top three treatment/prevention strategies used were reported as being free access supplementation (149), in feed supplementation (59) and direct to animal treatments (drenches, boluses and injections) (45) although these did vary by farm type. Although some (9) reported using Mg-lime, no other pasture management interventions were reported (e.g., Mg-fertilisation or sward composition). Generally, the results indicate that UK farmers are aware of the risks of HypoMgT. A more integrated soil-forage-animal assessment may improve the effectiveness of tackling HypoMgT and help highlight the root causes of the problem.

FARM ANIMAL PATHOLOGY AND DISEASE SURVEILLANCE TEAM VPC Director: Prof. Roberto La Ragione. Pathologists/Surveillance Officers: Dr. Benedetta Amato (Service Lead), Dr. David Harwood, Dr Laura Setyo, Dr Emma Borkowski. Epidemiologists/Consultants: Prof. Alex Cook, Pete Sewell, Andrew Watkins.

Surveillance Project Manager: Fernanda Haswell. VPC Administrator: Louise Ryan. Receptionist: Sue Grover-Smith. Technical Services Manager: Jon Cooper. Post-mortem Facilities Manager: Tom Hussey. Technical Staff: Mike Chaplin, Emily Tubb, Keith Hiley, Alice Robinson, Nic Scorovich, Ollie Skinner. Pathology Laboratory Manager: Katy Walker. Histology Technical Staff: Lucia Lozano White, Ella May.

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.