Pigs are resilient animals but, like all livestock, they hide the early signs of illness instinctively — a behaviour that evolved to avoid appearing vulnerable to predators. By the time an animal is showing obvious distress, the disease has often been present and progressing for days. Developing sharp observational skills during daily checks, and knowing specifically what to look for, is one of the most valuable skills a livestock keeper can develop.

This guide covers the most common and most important warning signs in pigs in Australian conditions. None of these signs is a diagnosis — they are indicators that require closer assessment, possibly veterinary advice, and prompt action.

1. Going off feed

A pig that refuses a meal it would normally eat eagerly is one of the most reliable early indicators that something is wrong. Pigs are typically voracious and consistent eaters — any individual repeatedly missing meals should be closely observed and their temperature taken. Normal pig rectal temperature is 38.5 to 39.5°C; above 40°C indicates fever and systemic illness.

2. Sneezing and nasal discharge

Occasional sneezing is normal; persistent, forceful sneezing with nasal discharge in multiple pigs suggests infectious disease. Atrophic rhinitis — caused by Pasteurella multocida and Bordetella bronchiseptica — is characterised by chronic sneezing, nasal discharge, and in advanced cases, a twisted or shortened snout from damage to the nasal turbinate bones. Porcine epidemic diarrhoea virus (PEDV) and other respiratory pathogens can also cause sneezing. Consult your vet if multiple animals are affected.

3. Coughing

Persistent coughing in pigs is not normal. Causes include enzootic pneumonia (caused by Mycoplasma hyopneumoniae), swine influenza, and other respiratory pathogens. A single coughing animal may indicate an individual airway irritation; multiple animals coughing suggests an infectious cause requiring veterinary assessment.

4. Diarrhoea

Scouring in pigs — particularly in weaners and growers — is one of the most common health challenges in pig production. Causes include bacterial enteritis (E. coli, Salmonella), rotavirus, post-weaning diarrhoea syndrome, swine dysentery, and nutritional causes. Age at onset and character of the faeces (watery versus bloody versus mucoid) guide diagnosis. Any pig with persistent diarrhoea and signs of dehydration (sunken eyes, dry skin) requires prompt attention.

5. Lameness and joint swelling

A pig that is reluctant to bear weight on a limb, has swollen joints, or is reluctant to rise and move may have joint ill (infectious arthritis, particularly in young pigs), foot injuries, or systemic illness affecting the musculoskeletal system. Sudden lameness in a pig on concrete is also associated with leg weakness — a condition common in fast-growing commercial lines that can be aggravated by slippery surfaces.

6. Skin changes

Multiple pigs in Australia can develop skin conditions ranging from the relatively benign to serious disease indicators. Thick, crusty skin on the ears, flanks, and face — greasy pig disease (exudative epidermitis, caused by Staphylococcus hyicus) — is a bacterial skin infection most common in young piglets. Circular, erythematous (red) lesions with a diamondback pattern on the skin of pigs suggest swine erysipelas, a serious bacterial disease requiring antibiotic treatment.

7. Sudden collapse or deaths

Sudden death or rapid collapse in pigs that appeared healthy — particularly in weaners on high-energy diets — suggests gut oedema disease (E. coli-associated), mulberry heart disease (vitamin E deficiency), or clostridial disease. Multiple sudden deaths in a group without clear cause requires immediate veterinary investigation and post-mortem examination to prevent further losses.

8. Reproductive failure

Sows that fail to come into oestrus, return to service repeatedly, have small litters, or experience mummified or stillborn piglets may have porcine reproductive and respiratory syndrome (PRRS), parvovirus, or nutritional deficiencies. Boars that show reduced libido or poor conception rates should have a breeding soundness evaluation — a single poorly performing boar in a small herd can dramatically reduce pregnancy rates before the problem is noticed.

When to call a vet

Any single animal showing multiple symptoms simultaneously, any situation involving multiple animals affected at once, any sign of neurological involvement (incoordination, circling, seizures), or any rapidly deteriorating animal should prompt immediate veterinary contact. Do not wait to see if the animal improves — the time lost in delay is frequently the margin between a treatable problem and a dead animal. Keep your vet's contact number saved in your phone and know the after-hours emergency number before you have an emergency.

For more on pigs health, see our Health Guide and FAQ page.

For more, see our Sick Sheep Symptoms: 10 Warning Signs Every Australian Farmer Should Know and Farrowing Checklist: Preparing for Piglets on Your Australian Farm.

Preventive Health Program

Many of the conditions above are considerably less likely with a basic preventive program in place rather than relying purely on early symptom detection. Core elements for Australian small-scale pig keepers include: a vaccination program appropriate to your region and risk (discuss with your vet — common inclusions are erysipelas and leptospirosis vaccination), a regular worming schedule (pigs are highly susceptible to internal parasites, particularly on ground they've occupied for extended periods), and iron supplementation for piglets in the first few days of life given sow's milk is naturally iron-poor. Routine observation — checking every animal daily for appetite, gait, breathing and general demeanor — remains the single most effective and lowest-cost tool available, since it's what catches problems while they're still cheap and simple to treat.

Biosecurity Basics for Small-Scale Keepers

Biosecurity is often thought of as a large-commercial-operation concern, but the basics matter just as much for a backyard producer with two or three pigs. Quarantine any new pig for at least two to three weeks before introducing it to existing stock, ideally with separate feeding equipment during that period. Limit visitor and vehicle access to pig areas, particularly from other properties keeping pigs, since several serious pig diseases spread readily via contaminated boots, equipment or vehicles. Never feed meat scraps or products containing meat to pigs — this is illegal in Australia under national biosecurity law, specifically because it's a known pathway for introducing serious exotic diseases like African swine fever into the domestic pig population. Report any unusual clustering of illness or death promptly to your vet or the Emergency Animal Disease Watch Hotline (1800 675 888) — early reporting of an unusual disease pattern is a genuine national biosecurity responsibility, not just good individual practice.