There's a lump on the back of my dog’s neck. What should I do? Lumps in dogs can occur for multiple reasons and there are a vast array of different types ranging from benign and harmless to highly malignant and potentially life threatening. A lump on the back of your dog’s neck can be any one of the lumps commonly seen in dogs, but it is worth also taking into consideration vaccination. If your dog has been vaccinated within the last three weeks it is fairly normal to be able to feel a small lump usually around 2cm in the scruff of your dog’s neck where the injection was given. Our vet explains about the possible causes of a lump on the back of your dog’s neck. Are you concerned about your pet? Meet a vet online!Included free as part of many pet insurance policiesHelp, treatment and if you need it, a referral to your local vetOpen 24/7, 365 days a year Book an appointment A lump on the neck can persist for a couple of weeks after a routine vaccination, however, this is rare. The lump may also be accompanied by other signs such as tenderness in the area, general lethargy and being off colour. If the lump seems to be growing, or your dog has not been recently vaccinated, it is important to book an appointment with your vet to perform a full examination and potentially sample the lump.Common causes of lumps in dogsVaccination site reactionSkin tagSkin reaction to an insect biteLipoma (fatty lump)Sebaceous cystAbscessHivesHistiocytomaWart (Papilloma)Hygroma (a soft swelling filled with fluid usually over a joint)HaematomaMast Cell TumourMelanomaSoft Tissue SarcomaSquamous Cell CarcinomaDiagnosis of your dog’s lumpThe lump is often sampled using a small needle to take some cells. These cells are analysed under the microscope to identify their origin and any indications of malignancy. Sometimes it is not possible to achieve a definitive diagnosis in this way, in which case your vet will recommend removing a larger biopsy sample, or the whole lump, for analysis. This is usually performed under general anaesthesia. Surgery may be straight forward or complex depending upon size, location, infiltration into surrounding tissue and the type of mass present.If analysis of the lump indicates a malignant tumour then sometimes further treatment such as chemotherapy or radiotherapy is required.Remember! Not all lumps in dogs are cancerous but having them examined by your vet and tested is the safest way to monitor any lumps and bumps your dog might have.When to see your vet?The lump has persisted beyond 3 weeksThe lump has rapidly changed in size, shape, colour or changes in the overlying skinThe lump is accompanied by any of the general signs aboveStill worried?Book a video appointment to have a chat with one of our vets.