Malaysia Veterinary Forum (Archive)

Dr csh · Joined: 21 Jan 2006 Posts: 425

Most of us have never heard of MCF affecting swine... at least I had not when I graduated from vet school. Let me guide you through the history.

I was called one day to examine an inappetent pig. When I got to the barn, I saw an adult large yorkshire cross that was visably lethargic. There were 2 other pigs on the premise one was a berkshire cross and another a duroc polish spotted cross which seemed fine. There were 3 sheep also in the pen next to the pigs but they were fine.

Physical exam on the pig was unremarkable except a mild fever, scant feces and lethargy. I really did not know what was wrong with the pig but I knew there was something wrong and the owner was more than willing to send it into the hospital for a full work up. It was hospitalized for a week or so and when they realized the condition was deteriorating, they euthanized it and sent it for necropsy.

I'm not sure what they found grossly but the pathologists thought that the histological lesions were similar to MCF and she had read an article about MCF in pigs from a scandinavian journal. Of course MCF has never been reported in pigs in the US so it would have been a first. Samples were sent to Washington Animal Disease Diag Lab for PCR and antibody ELISA for Ovine herpes virus type 2 and both tests were positive...... Of course this increased our suspicions.

So, I went back to the farm and collected samples from the remaining pigs and sheep on the farm and submitted the samples for PCR and ELISA. One pig was positive on ELISA but negative on PCR and the other pig was negative for both. All 3 sheep were positive both for PCR and ELISA. The positive antibody ELISA in one of the pigs could have meant seroconversion but no OvHV-2 was found on PCR.

It has been almost a year and a half since the tests and the pigs and sheep are doing fine although they are no longer kept in the same area.

In summary, it is likely that MCF may infect pigs but it would be a weak infection and should not be too high on your differential lists. However, as most herpes infection in abbarent hosts, it seems like MCF, once contracted, do not respond readily to therapy.

Hope you enjoyed this interesting but ultimately insignificant case report :)

varanus · Joined: 12 Feb 2006 Posts: 469

Do you see any changes in the eyes? Any discharges, from the nose? Or just alimentary form?

Very interesting because apparently only cattle, buffalo, deers are affected. First time hear in swine. Is there anyway you can find out about the necropsy report and histopath finding?

Dr csh · Joined: 21 Jan 2006 Posts: 425

There were no typical MCF clinical signs such as muco purrulent ocular or nasal discharges nor were there laminitis signs or even diarrhea.

I had never heard of MCF in swine either and it was the first reported case in north america in swine. About th necropsy report and histopath findings, I will have to get back to you on that.

Dr csh · Joined: 21 Jan 2006 Posts: 425

I did not see or noticed any ocular or nasal discharge when I saw it and referred it to the teaching hospital.
I re-read the necropsy report and I saw that the pig later developed stertor which worsened with more pronounced and increasingly muco-purrulent nasal discharge. The pig also started developing vestibular signs after consult by a Neurologist was thought to be central dx meningitis. This neurological and respiratory signs progressed until nares almost non-patent and profound ataxia, collapses and was euthanased.

Gross lesions:
- small cyst on right kidney (common incidental finding)
- petechiation on kidney parenchyma, mesentery and pancreas, epicardium
- mild rostral, ulcerative rhinitis and mild chronic otitis externa.

Brain, and spinal chord was grossly normal but as the animal was a rabies suspect and a section was submitted for rabies testing (which was negative).

Histological diagnosis:
Brain and spinal chord: severe multifocal, subacute, lymphocytic and histiocytic meningoencephalitis, myelitis and choroid plexitis
Brachial plexus and sciatic nerves: Moderate, moltifocal, subacute, lymphoplasmacytic and histiocytic perineuritis
Kidney: Severe, multifocal, subacute lymphoplasmacytic and histiocytic interstitial nephritis with severe fibrinoid vasculitis and focal renal cyst
Heart: Mild, multifocal, subacute, lymphocytic myocarditis
Lung: Moderate, multifocal subacute lymphocytic and histiocytic peribronchitis, pleuritis and vasculitis
Pancreas: Moderate, multifocal, subacute lymphocytic and histiocytic necrotizing pancreatitis and multifocal fat necrosis
Stomach: Severe, multifocal, lymphoplasmacytic and histiocytic erosive gastritis
Liver: Mild, multifocal, subacute, lymphocytic, periportal hepatitis
Nose: Severe, multifocal, acute to subacute, lymphocytic and histiocytic, rhinitis with fibrinoid vasculitis, hemorrhage and edema
Eye: Severe, locally extensive, acute to subacute, lymphocytic and histiocytic panophtalmitis and neuritis.

If you are interested in more details in the histological findings of a particular part of the brain or organ, I can give you a far more thorough report but I am getting tired just typing this much!

varanus · Joined: 12 Feb 2006 Posts: 469

From the histopath report, with all the mononuclear infiltration and perivascular cuffing, it sounds very much like MCF. Thanks for your report. What' s the advice to the farmer. In cattle we know need to separate the shhep from the cattle, how about the swine?

I am not sure about other diseases, but do you think you can squenze in Pseudorabies or Nipah into the DDx?

Dr csh · Joined: 21 Jan 2006 Posts: 425

Well, the advice to the owners (it was a pet pig) was to seperate the sheep from the pigs. It is unlikely that the OvHV-2 cross species to pigs easily since the pigs and sheep have been living together for years and only one pig came down with the disease. I've seen how easily MCF transmits from sheep to cows and even without direct contact. It just does not behave the same way with pigs.

Yes, I suppose you could add those disease into the differential lists but both pseudorabies and Nipah behave differently. I would not expect pseudorabies to kill an adult pig and I would suspect at least one of the cats if not the sheep that live in the barn would develop mad itch. Nipah could be the problem as it affects some pigs more than others. To be honest, I do not know how gross lesions of nipah would look like but I imagine the histology might be similar... maybe somebody can enlighten me.