ALABAMA Rot or Cutaneous and Renal Glomerular Vasculopathy (CRGV) is a condition I’m not aware encountering in general practice and only recollect being briefly mentioned at college as a rare disease of greyhounds with the last confirmed case in the UK being reported back in the early 2000s.
That was until three years ago when, between December 2012 and February 2013, four dogs, all from the New Forest, were referred to Anderson Moores Veterinary Specialists (AMVS) with acute kidney injury (AKI) having developed skin lesions several days earlier.
Two of these dogs were sadly euthanased due to their disease; post-mortem examination revealed thrombotic microangiopathy (TMA), a finding consistent with CRGV.
Since December 2012 there have been 56 confirmed cases of CRGV reported from all over the country and to help raise awareness, The Webinar Vet arranged for David Walker from Anderson Moores to discuss this devastating disease.
He explained CRGV has been recognised for around 30 years and was generally confined to the greyhound population in the USA. The aetiology remains unknown although it appears to be a disease affecting young to middle-aged greyhounds with no sex predilection.
CRGV is characterised by a TMA causing damage to the vascular endothelium with widespread formation of microthrombi within the skin and kidneys which variably leads to consumptive thrombocytopaenia, microangiopathic haemolytic anaemia and acute kidney injury.
Interestingly, historical studies in the USA showed some dogs developing skin lesions only, others developing acute kidney injury (AKI) only and some developing both. From these studies the question has to be asked whether some dogs in the recent outbreak in the UK just developed skin lesions without going on to develop AKI and, if this is the case, are these cases passing us by without a diagnosis?
There have been 56 cases of CRGV confirmed by post-mortem since 2012 and most of these cases were seen between the months of November to April, indicating seasonality to the disease process. From these 56 cases, David and colleagues analysed data from 30 dogs and the results showed CRGV was no longer a disease found predominantly in greyhounds but can affect a wide range of breeds and any size of dog (from a JRT to a flat coated retriever). The age of these animals ranged between one and 12 years with an average age of five years.
The distribution of this CRGV outbreak initially seemed biased towards Hampshire but David believes this was probably awareness-driven as over time the proportion of cases in Hampshire has reduced and CRGV now appears to be a disease with a nationwide distribution.
Clinical presentation
Skin lesions tended to develop in most cases before systemic signs were seen. Nine out of the 30 dogs showed systemic illness at the same time. Skin lesions were usually seen in the distal limbs and most appeared superficial with most vets attributing the lesions to wounds, bites, stings and focal dermatitis at initial consultation.
More marked dermal signs were also noted and included erythema, oedema and ulceration. If not already present, dogs would go on to develop clinical signs of acute kidney injury on average around four days after presenting with skin lesions.
Clinical pathology
Seven out of 30 dogs were anaemic at the time of presentation and eight more went on to develop anaemia; 15 were thrombocytopaenic at presentation and four became thrombocytopaenic.
The average platelet number (46 x 10(9)/L) measured in these thrombocytopaenic dogs sat just above the level expected for spontaneous bleeding (30 x 10^9/L).
Twenty-six dogs were azotaemic and nine were hyperbilirubinaemic at presentation. A further four went on to develop hyperbilirubinaemia during hospitalisation.
Leptospirosis was tested for in these cases as it was considered a potential differential diagnosis. Some tests proved positive but David explained dogs can be maintenance hosts where organisms can be detected without causing any clinical signs.
As there should be a survival rate of 70% with dogs suffering from leptospirosis and as the presence of skin lesions does not fit the clinical picture for leptospirosis, it was assumed these cases had not developed AKI as a consequence of leptospirosis and were indeed asymptomatic maintenance hosts.
Outcome
Of the 30 dogs analysed, 24 were euthanased on welfare grounds and six were euthanased at the owners’ request. The mean time from presentation to euthanasia was seven days despite aggressive treatment for AKI.
Antibiotics were given to 27/30 dogs; an anti-inflammatory dose of steroids was given to 7/30 and an immuno-suppressive dose was given to 1/30. These medications appeared to make no difference to the outcome of these patients.
As stated previously, there have been 56 confirmed cases of CRGV and this diagnosis was made at post-mortem where TMA could be identified at histopathology.
David explained there have been eight further cases which survived and although CRGV was not confirmed there was a very high index of suspicion for the disease. When this group of patients were compared to those that did not survive there appeared to be no difference in age, breed, sex or clinical pathology results. However, this is not a big data set from which to draw conclusions.
Unanswered questions
By raising awareness of CRGV, David is hoping to gather a much greater database from which further information can be derived about this often fatal disease.
For example, is there a population of dogs which develop skin lesions without developing AKI and consequently go on to survive? With such a small database to call on, is this disease really seasonal? Is there a specific treatment out there which can help?
Currently we just don’t know the answer to these questions and many more and David hopes with greater awareness amongst vets, further cases can be identified from which further data can be compiled.
Unusual skin lesions?
If at all concerned about a patient presenting with unusual skin lesions David advises measuring a baseline creatinine level which, in dogs suffering from CRGV, is likely to increase over two to three days. Urinalysis can also prove useful to check for protein loss secondary to renal glomerular injury.
A drop in GFR could also be seen and David urges contacting Anderson Moores who can advise vets further. The practice is also collating data on cases nationally.
David discussed many aspects of CRGV in much greater depth during this webinar, even comparing it to some similar conditions in humans. Clearly this is a disease which needs considerably more research and by raising awareness to vets all over the country, we can identify more cases of CRGV and gather further data so we are better prepared to try to prevent, diagnose and manage these cases.
The Webinar Vet has provided an important platform on which awareness about Alabama Rot can be raised and I urge you to watch this veterinary webinar to find out more about this devastating disease.
