Craig R. Breheny

A 10‐year‐old, female, neutered cocker spaniel presented for surgical debulking of an axillary and cranial thoracic wall liposarcoma. Pre‐surgical blood analysis demonstrated anaemia (packed cell volume 17%), leukocytosis (white blood cell count 43.95 × 10 9 /L) and thrombocytopenia (15 × 10 9 /L), with platelet loss secondary to chronic intra‐lesional haemorrhage or immune‐mediated destruction, and concomitant Staphylococcus pseudintermedius urinary tract infection. A blood transfusion and antibiotics were administered before surgery. Within 48 hours after surgery, an extreme leukocytosis (white blood cell count 170 × 10 9 /L), involving a severe left shift neutrophilia (95 × 10 9 /L) was observed; this resolved within 10 days. Serum granulocyte‐colony stimulating factor levels were similar to controls. The extreme leukocytosis was suspected to be related to a paraneoplastic leukaemoid reaction combined with an expected postoperative mild leukocytosis. Further investigation into the pathophysiology underlying similar cases is required. One month after surgery, all haematological abnormalities had normalised, and metronomic chemotherapy with chlorambucil commenced.

A 3‐year‐old labradoodle presented with prior history of generalised seizures and had recently developed acute pyrexia and shifting leg lameness, with joint effusions in several joints. The dog also later developed pleuritis with an exudative pleural effusion. Cytological findings for all joint effusions were consistent with immune‐mediated polyarthritis. Suspected lupus erythematosus cells were seen in the joints and pleural fluid, which were confirmed with Feulgen staining. Together with a positive antinuclear antibody titre, the dog was diagnosed with systemic lupus erythematosus, which responded to immunosuppressive doses of prednisolone. This case report describes the insidious nature of systemic lupus erythematosus, a rare disease that can imitate many different conditions. It is also the first reported case of lupus erythematosus cells in pleural effusion in veterinary medicine, highlighting the importance of lupus erythematosus cells as a valuable diagnostic aid to further support the diagnosis of systemic lupus erythematosus and enable early treatment to be initiated.

Case series summary Cats with non-erosive immune-mediated polyarthritis (IMPA) were identified from seven referral hospitals between 2009 and 2020 for a multicentre retrospective case series. Data were obtained from hospital records and referring veterinarians were contacted for follow-up. Twenty cases were identified: 12 castrated males (60%), one entire male (5%) and seven spayed females (35%). Common clinical signs included lameness (n = 20/20) and pyrexia (n = 10/18). Three cats presented with and two cats developed ligament laxity during treatment. Thirteen cats (65%) were diagnosed with non-associative IMPA and seven (35%) with associative IMPA. Comorbidities identified included chronic enteropathy (n = 3/7), feline immunodeficiency virus (n = 1/7), feline herpesvirus (n = 1/7), bronchopneumonia (n = 1/7) and discospondylitis (n = 1/7). Sampling of the tarsal joints most frequently identified an increased proportion of neutrophils, consistent with IMPA. Eighteen cats (90%) received immunosuppressants. Eleven cats were started on prednisolone; eight had a poor response resulting in the addition of a second agent, euthanasia or acceptance of the persisting signs. One cat received ciclosporin and required an alternative second agent owing to adverse effects. Five cats were started on prednisolone and ciclosporin; three had a poor response and required an alternative second agent. One cat received prednisolone and chlorambucil and had a good response. Two cats (10%) received meloxicam and had a good response, although the clinical signs recurred when medication was tapered. A good outcome was achieved in 14/20 cats (70%) with IMPA. In the cats with a poor outcome 4/6 were euthanased and 2/6 had chronic lameness. Relevance and novel information Prognosis for feline IMPA can be good. Multimodal immunosuppression was often required. IMPA should be considered in lame cats, with or without pyrexia, when there is no evidence of trauma or infection. The tarsal joints should be included in the multiple joints chosen for sampling. Ligament laxity can occur in non-erosive feline IMPA.