# Mycobacterium avium Infection in a Domestic Shorthair Cat Following Subdermal Hyaluronic Acid Filler Injection

## TL;DR

A cat developed a rare infection after a hyaluronic acid injection, which was successfully treated with a combination of antibiotics.

## Contribution

This is the first reported case of non-tuberculous mycobacterial infection in a cat following hyaluronic acid injection.

## Key findings

- Mycobacterium avium subsp. hominissuis infection was confirmed in a cat after subdermal hyaluronic acid injection.
- Intralesional amikacin injections helped reduce eyelid swelling and lymph node enlargement in the cat.
- Mycobacterial PCR became negative 4 months after diagnosis, and no recurrence was observed 18 months later.

## Abstract

To describe the diagnosis and treatment of a
Mycobacterium avium
(
M. avium
) infection in a cat following subdermal hyaluronic acid (HA) filler injection.

A five‐year‐old spayed female domestic shorthair cat with chronic inferior lateral entropion and chronic feline atopic skin syndrome (FASS).

Left inferior eyelid swelling and ipsilateral mandibular lymphadenomegaly developed approximately 2 weeks following subdermal HA injection OU. Culture of a fine needle aspirate (FNA) from the affected lymph node confirmed a
Mycobacterium avium
subsp. hominissuis infection resistant to most conventional antibiotics including fluoroquinolones and rifampin. Clinical response to sustained clarithromycin was poor and antitubercular isoniazid was poorly tolerated. As adjunctive therapy, two sequential intralesional injections with amikacin (12.5 mg/kg total dose per treatment) were performed into the affected eyelid and lymph node. Clinical reductions in eyelid swelling and lymphadenomegaly were observed thereafter. Approximately 4 months after diagnosis, mycobacterial PCR from an FNA of the affected lymph node was negative. Antibiotic therapy was completed approximately 6 months following diagnosis. No clinical signs of infection recurrence were present at the time of writing approximately 18 months following completion of antibiotic therapy.

Non‐tuberculous mycobacterial (NTM) infections are a known and documented complication of subdermal filler injections in human patients. This is the first described case of NTM infection associated with HA injection in a cat. Treatment success with conventional oral antibiotics may be limited, necessitating extended therapeutic courses and alternative drug delivery routes like intralesional injection.