PID SPOTS PRACTICAL - Infectious diseases of the alimentary system

Question 1

2 pathogenetic mechanisms of diarrhoea in calves and piglets

Answer 1

MALABDSORPTIVE - viruses destroy epithelial cells, loss of cells means loss of absorptive mechanisms and enzymes, accumulation of ions, proteins and sugars draws water into lumen from cells. Water absorption is reduced as Na absorption is reduced
SECRETORY - ETEC enterotoxins increase chloride secretion, leads to increased osmotic pressure in lumen of GIT, draws water in from cells

Question 2

Vaccine to control diarrhoea in calves. How about an oral vaccine? What about pigs?

Answer 2

Vaccines available against rotavirus, coronavirus and ETEC for the dam to increase antibodies in colostrum. Vaccines against Cryptosporidium are not available. Oral vaccines containing these components for use in newborn calves are also
available but efficacy is controversial
The same principle applies for the protection of piglets (vaccination of sows)
Vaccines contain ETEC antigens as well as Clostridium perfringens toxoid (no
rotavirus or coronavirus vaccines are licensed for pigs in the UK).

Question 3

What causes infectious canine hepatitis?

Answer 3

Canine adenovirus type 1

Question 4

What does Canine adenovirus type 1 infect? 2

Answer 4

hepatocytes and endothelial cells

Question 5

Clinical signs of canine adenovirus type 1?

Answer 5

vomiting
S/c oedema (head, neck and trunk)
centrolobular necrosis

Question 6

Clinical signs of a dog with Campylobacter jejuni

Answer 6

diarrhoea, some abdominal pain, normal temperature, still eating and drinking, Campylobacter jejuni in faecal sample

Question 7

Define AFB. How would you detect it?

Answer 7

Acid fast bacteria - Ziehl Nielson stain (appears blue)

Question 8

Name 2 hameorrhagic notifiable diseases of pigs

Answer 8

African Swine Fever and Epizootic Haemorrhagic Disease.

Question 9

What causes Porcine Proliferative Enteritis?

Answer 9

Lawsonia intracellularis

Question 10

What happens if you detect E coli in faeces?

Answer 10

It is very common to find non-pathogenic E.coli in faeces. Very rare to be able to perform tests to confirm the presence of F4/F5 and toxins.

Question 11

Describe lesions of BVDV

Answer 11

Erosions on the gum, roof of the mouth and tongue (NO vesicles)

Question 12

When do BVDV positive animals show lesions?

Answer 12

Mucosal disease caused by bovine viral diarrhoea virus. Persistently infected animals are often (but not always) “poor doers”. They were infected with BVDV non-cytopathogenic in utero and do not mount an immune response to BVDV (at least not to strains that are antigenically similar to the one they were infected
with). If the strain with which they are persistently infected mutates to a cytopathogenic BVDV strain they develop mucosal disease which is usually fatal.

Question 13

Describe FMDV lesions

Answer 13

Vesicles on the mucosa of the tongue or on the snout, some vesicles have ruptured
Erosions and skin necrosis (in older lesions 3-2)

Question 14

What lesion is highly suscpicious of FMDV?

Answer 14

Any vesicles on oral mucosa and skin (and on feet)
are highly suspicious of FMDV. Mucosal disease for example does not cause vesicles. Older FMDV lesions may be less straightforward to recognise.

Question 15

What other vesicular lesions are notifiable in farm animals?

Answer 15

Other vesicular diseases of cattle (vesicular stomatitis) and pigs (swine vesicular disease and vesicular stomatitis) are also exotic and notifiable.

Question 16

Clincial signs of canine adenovirus 1 induced canine infectious hepatitis….

Answer 16

Anorexia, depression, abdominal pain, sudden death is possible. Some dogs show petechial haemorrhages on mucosal membranes and skin (coagulation affected due to damage to liver and bleeding due to damage to
vascular endothelium)/ Canine adenovirus type 1 is now rarely seen due to good vaccine uptake. It has
to be considered though in unvaccinated dogs. Long term shedding of the virus in urine is possible and dogs may contract the virus from the environment without direct contact to infected dogs.

Question 17

Should you treat a Campylobacter jejuni infection in a dog with antibiotics?

Answer 17

Treating with antibiotics is not recommended in humans but many vets still do treat. The infection is self-limiting but can take several days to resolve.

Question 18

Clinical signs - Campylobacter jejuni - in humans…

Answer 18

Campylobacter jejuni can cause a serious, bloody, mucoid diarrhoea in humans. Children can be severely affected.

Question 19

Other than a ZN stain, how can you confirm Map infection?

Answer 19

A blood ELISA test for antibody or a PCR on the faeces.

Question 20

What treatment or control measures are necessary for Johne’s disease?

Answer 20

Antibiotic treatment has been tried but with little success unless in the early stages. Reinfection after treatment is likely because the organisms survive in the environment. Vaccination is available for very young animals.Otherwise test and slaughter to try and eradicate or slaughter animals showing wasting.

Question 21

What complex is porcine haemorrhagic enteropathy a part of?

Answer 21

The PIA complex = porcine intestinal adenomatosis

Question 22

4 methods to control notifiable pig gastro diseases

Answer 22

Biosecurity, prophylactic, antimicrobials, vaccination