Phenobarb/KBr as a cause of Protein Losing Nephropathy??

Re: Phenobarb/KBr as a cause of Protein Losing Nephropathy??

Andrew Kent — Thu, 29 Jan 2015 18:13:08 GMT

Thanks for the update Louise, I would suggest that you check the renal parameters 3-5 days after starting the ACEi to ensure that the drop in GFR doesn't lead to a significant azotaemia.

Please keep us updated with how you get on,

Andy

Re: Phenobarb/KBr as a cause of Protein Losing Nephropathy??

Louise Smith — Thu, 29 Jan 2015 15:00:02 GMT

Thank you very much for your replies. Despite the high dose the last phenobarb level was 26, so around the middle of our labs ref range (14-40). I will definitely get a urine sample and run a UCCR to see if I can rule Cushings out and its reassuring to know that renal biopsies aren't necessarily required to guide treatment of proteinuria. I have already started the dog on an ACEi and if I don't get anywhere with a diagnosis of Cushings then I'll start her on a renal diet and omega 3 too.

Thanks

Louise

Re: Phenobarb/KBr as a cause of Protein Losing Nephropathy??

Andrew Kent — Tue, 27 Jan 2015 22:49:48 GMT

Hi Louise,

I think it is unlikely that this is drug related, but I share Anthony's suggestion to check the serum levels of these drugs to make sure that you are within the therapeutic and not toxic range. PUPD and hepatomegaly are both reported as a result of phenobarb, though my experience is the hepatomegaly tends to be fairly mild.

This degree of proteinuria is higher than you typically expect as a steroid effect but never say never. Unfortunately dogs on phenobarb can look very like dogs with HAC so it could be difficult to determine. A urine cortisol:creatinine ratio on a relaxed morning sample might be a good screen to see if you can exclude the disease with a normal ratio before considering ACTH/LDDST.

In terms of management of the proteinuria - yes a renal biopsy is nice in these cases but it doesn't often change what you do so I understand if it is declined. If you do take one then submit it to one of the centres involved in the WSAVA renal biopsy standardisation scheme not just for standard light microscopy.

The evidence base behind interventions is rather lacking, there is a 2004 ACVIM consensus statement which you can read HERE on this topic, in brief it would suggest a renal diet, omega 3 supplementation and an ACE inhibitor (with close monitoring of renal function).

This dog is well over the suggested level for treatment and so I would definitely advise it.

Hope this helps and do keep us updated with how you get on,

Andy

Re: Phenobarb/KBr as a cause of Protein Losing Nephropathy??

Anthony Dennison — Tue, 27 Jan 2015 14:43:29 GMT

I'm sure Mark Lowrie or some of the internal medics will be along soon and give a better answer, but that seems like quite a high dose of phenobarb, what are the serum levels like? High or low end of normal? When you say a cluster seizure, how many seizures does she have in that 48hr period? Not perfect control, but often it is hard to get this. Have they slowly increased in frequency until every 6-8 weeks, or has it always been like this?

I had a dog on high doses of phenobarb and it looked like you described, I switched to Keppra and these signs resolved. However, Keppra has a 'honeymoon period' where it works fantastically but then we had to increase the dose, and add in lower doses of phenobarb later on. I started at 10mg/kg Keppra, but it can be increased up to 30mg/kg in some cases.

There is a possibility that the dog could be cushingoid, maybe whatever is causing the seizures isn't idiopathic epilepsy and is leading to changes in the pituitary gland...