Anderson Moores Vet Specialists take referrals from vets; research treatments and causes of Alabama Rot. The presentation covered the background, literature, case information and prognosis of CRGV.

On 23rd June 2015 I attended a presentation by David Walker BVetMed(Hons) DipACVIM DipECVIM-CA MRCVS from Anderson Moores Veterinary Specialists (AMVS) on cutaneous and renal glomerular vasculopathy (CRGV) (aka Alabama Rot). The meeting was at Sparsholt Agricultural College near Winchester. About 30 vets, vet nurses and others attended the meeting.

Davids’ presentation covered the background, previous literature, case information and prognosis of CRGV.

Background

It all began with four cases of dogs with AKI* and skin lesions from the New Forest between December 2012 and February 2013. Post mortem revealed Thrombotic Microangiopathy (TMA) in which damaged endothelial and red blood cells block blood vessels. reducing blood flow, leading to AKI within 10 days and subsequent organ death. CRGV was suspected.

* Acute Kidney Injury (AKI) is a sign of CRGV in most cases. AKI is an acute deterioration of renal functions within 48 hours leading to increased serum creatinine levels and reduced urine (oliguria).

Previous Literature

David said that he had spent just 2 minutes on CRGV in vet school! David presented the previous literature on CRGV citing half a dozen papers since the 1980s.

Case Information

David summarised the confirmed cases to date:

• Nov 12 - Mar 13: 10 cases
• Dec 13 - Jun 14: 31 cases
• Sep 14 - 1 outlier case
• Nov 14 - May 15: 16 cases

The latest March 2015 paper by Laura Holm and David Walker reviewed 30 cases (of 58 dogs of which 9 survived). David estimated that over 100 dogs have died of CRGV in the UK since November 2012 - a further 11 or 12 have survived.

During 2014/15 proportionally fewer dogs died in Hampshire - this suggests that the high proportion of cases in the New Forest in 2012/13/14 might be due to greater awareness of CRGV by local vets (Anderson Moores are located in Winchester, Hampshire), said David.

From the confirmed cases map I’ve summarised the cases, in the New Forest compared to total UK cases:

• 2012 - 2013: 4 cases in New Forest of 10 UK cases (40%)
• 2013 - 2014: 9 cases in New Forest of 30 UK cases (30%)
• 2014 - 2015: 2 cases in New Forest of 16 UK cases (12%)

Clinical signs of CRGV are skin lesions in all 30 cases and anorexia, vomiting, lethargy and hypothermia in two thirds of cases.

CRGV does not appear to be Leptospirosis. Additional tests undertaken have been for Circovirus, viral metagenomics (known viruses), 16s rRNA-directed probes (known bacteria), Borrelia (Lyme disease), heavy metals and urine toxicology (ethylene glycol poisoning).

Of the 9 surviving dogs, 2 were treated at RVC with Plasma Exchange (NB. both dogs had low creatinine levels).

The differential diagnosis (DDx) for canine TMA is;

• CRGV
• Haemolytic Uremic Syndrome (HUS) - only reported in 5 dogs worldwide and non had skin lesions. In humans, HUS (STEC-HUS or D+ HUS) is most common in summer, in small geographical clusters (eg in 2009 in Surrey) and sometimes associated with E.coli shiga toxin.
• Disseminated Intravascular Coagulation (DIC) - but CRGV only affects kidneys and no other organs and coagulations are normal.
• atypical HUS (aHUS) in people have complement dysregulation possibly triggered by the environment or diet. Skin lesions are rare. No reports of aHUS in dogs.

Depending on the underlying cause, according to David Walker (AMVS) TMA management is by:

• Plasma (fluid therapy) - which dampens down symptoms
• monoclonal Shiga toxin antibodies
• Anti-C5 antibodies for aHUS. I note that in 2015 Eculizumab by Sotiris was funded for use in UK people.
• According to David Walker (AMVS), Plasma Exchange costs £15,000. All dogs with CRGV treated by Anderson Moores get offered Plasma Exchange (David said that this is a precaution in case it is shown in 10 years time that CRGV is treatable by Plasma Exchange).
• Renal transplantation

Unanswered Questions

• Is CRGV a novel disease or does it represent STEC-HUS, aHUS or something else?
• Why did 43% of dogs in contact with a dog with CRGV develop skin lesions but no AKI?
• Is CRGV seasonal?
• What is optimal management for CRGV?
• What should be procedure for dogs with skin lesions?

Prognosis

CRGV has a 80-85% mortality compared to Lepto 15% mortality.

Take Home Messages (THM)

• CRGV is a disease of unknown aetiology
• CRGV affects breeds other than greyhounds
• Skin lesions typically appear <1 week before clinical signs attributable to AKI
• Thrombocytopaenia is seen in 75% of cases
• Anaemia and jaundice may be seen
• Prognosis may be poor (80-85% mortality rate)

Veterinary Record March 2015 Paper by Laura Holm, David Walker et al

Available free on this website.

Management of AKI

David Walker explained the management of AKI including:

• fluid therapy (to prevent dehydration)
• Furosemide (first line drug)
• Mannitol
• Dopamine
• Continuous Renal Replacement Therapy (CRRT)/Dialysis/Plasma Exchange
  • in the 2 cases at Royal Veterinary College (RVC) both dogs had only mild Thrombocytopaenia
• Monitoring
  • Body weight, blood pressure, electrolytes etc
• Overhydration
• Gastroprotectants
• Anti-emetics
• Nutrition
• Tapering Fluid Therapy
  • creatinine levels

Acknowledgements

David Walker acknowledged:

• Laura Holm MRCVS
• Royal Veterinary College (RVC)
• Animal Health Trust (AHT)
• New Forest District Council
• Forestry Commission
• Forest Veterinary Clinic
• UC Davis Veterinary Medicine
• New Forest Dog Owners Group
• Texas A&M University

Questions to David Walker

I asked ‘With a CRGV survival rate of 10-15% what should be our target if vets were to follow your ‘best practises’ eg fluid treatment. David replied that a CRGV dog survival rate of 60% should not be unrealistic (similar to non-CRGV AKI).

I also asked ‘ Could Eculizumab C5 antibody be used to treat CRGV? David replied that further work is required on canine complement system since it differs from the human compliment system.

 

Chris Street BSc (Hons) MBA PGDipMedChem

www.alabamarot.co.uk