Lena Dunham stands by her claims that her pet dog was abused before she adopted him from a shelter.

The Girls actress adopted Lamby in 2013 from the BARC animal shelter in Los Angeles but returned him in March after battling with his allegedly "challenging behaviour and aggression". Dunham's allegations that Lamby was abused as a puppy were strenuously denied by the shelter but the actress refuses to back down.

In a new and incredibly lengthy Instagram message posted on 7 July, Dunham writes: "It's come to my attention that the staff at the shelter where I adopted Lamby have a very different account of his early life and behavioural issues than I do.

"While I'm sorry to have disappointed them, I can't apologise. Lamby was and is one of the great loves of my life. When I met him I knew we'd have an amazing journey. But his aggression – which was unpredictable – and his particular issues, which remain myriad, weren't manageable, at least not by me."

Dunham, 31, goes on to reveal how she still supports Lamby financially and believes he is in a "much happier" environment. Clearly emotional after the ordeal, Dunham continued: "I hope those judging can imagine the incredible pain of letting go of your favourite creature on EARTH because you know you can't help them be healthy and happy.

"I would never say an unkind word about the staff of BARC, what they do is amazing and life saving for these animals – but we have different accounts of Lamby's behaviour and they were not present in my home nor did they live with him for an extended period. They did not witness the consistent and responsible care I provided. I have weathered a lot of micro-scandals but this one hurts MOST, because of the vulnerability of letting people know Lamby and my story, and because I miss him so damn much."

I need new 'Girls' episodes immediately

A post shared by Lamby Antonoff-Dunham (@lamby_antonoff) on

Barc have responded to Dunham's claims in their own statement, in which Robert Vazquez argues: "When she adopted the dog from us, it wasn't crazy. I have pictures of the dog loving on Lena and her mum, which is weird if the dog was abused. It wouldn't be cuddling with her or be in the bed with her 'boyfriend' in the pages of Vogue.

"If Lamby had a bad past or was abused, do you think BARC would have adopted him to Lena knowing she's a new star and put her — or the dog — in that situation? We would have told her if the dog had issues. We are a no-kill shelter. We don't lie about the dogs' histories because that gets them returned — and mentally it's not good for dogs."

Lamby, who is now said to be residing with a specialist handler in Los Angeles, featured in a photo shoot for Vogue magazine alongside Dunham, who also detailed his adoption in an issue of the New Yorker.