When a Dog Keeps Getting Sick, the Immune System May Hold the Answer
Recurrent pneumonia in dogs is a red flag — one bout can happen to any dog, but infection after infection, especially when it’s hard to treat, points to something deeper. A case report published in Frontiers in Veterinary Science describes exactly that scenario: a Bernedoodle who developed repeated, drug-resistant lung infections and ongoing stomach and gut problems. When veterinarians dug further, they found the root cause — selective IgA deficiency, a gap in the dog’s immune system that left it unable to properly defend its airways and digestive tract.
This is a single case report involving one dog, so it can’t tell us how common the problem is. But it offers a valuable reminder: when a dog keeps getting infections, especially in more than one part of the body, investigating the immune system may be a critical next step.
What Is IgA — and Why Does It Matter?
IgA (immunoglobulin A) is a type of antibody — one of the proteins your dog’s immune system makes to fight germs. What makes IgA special is where it works. Unlike some antibodies that patrol the bloodstream, IgA is found mainly at the body’s surfaces: the lining of the lungs, the gut, the nose, and the mouth. Think of it as the first line of border security, standing guard at the entrances where bacteria and viruses try to get in.
When a dog has selective IgA deficiency, it means the immune system doesn’t make enough of this specific antibody. Everything else may look fine — but that one layer of protection is missing. Without IgA doing its job at the body’s surfaces, germs that would normally be stopped can get a foothold and cause repeated infections.
What Happened to This Dog
The dog in this case was a Bernedoodle — a crossbreed of Bernese Mountain Dog and Poodle — that came in with a history of infections that kept coming back despite treatment. The lung infections were caused by bacteria that had become resistant to multiple antibiotics. That “multidrug resistance” is a serious complication: it means the usual treatments didn’t work, making each episode harder to manage.
The dog also had chronic enteropathy — a long-term condition causing gut symptoms like vomiting, diarrhea, or poor digestion. The gut problems weren’t separate bad luck. They were part of the same picture: without IgA protecting the digestive lining, that surface was also vulnerable.
After a thorough workup, veterinarians identified the selective IgA deficiency as the underlying reason for both sets of problems. The immune gap was affecting the dog at both ends — lungs and gut — because both are surfaces that rely heavily on IgA for defense.
Why Drug-Resistant Infections Are a Bigger Concern Than Standard Ones
Multidrug resistance means bacteria have developed ways to survive common antibiotics. In a healthy dog, the immune system might help clear these bacteria even when drugs struggle. But in a dog with IgA deficiency, the immune system is already working with a missing piece — so it has even less backup. The result can be infections that are harder to treat, take longer to resolve, and come back more quickly.
This is why the case stood out to the reporting veterinarians. The pattern of repeated, hard-to-treat infections in two separate body systems pointed them toward an immune investigation rather than just treating each infection as an isolated event.
What This Case Suggests for Dog Owners
This was a single dog, and findings from one case can’t be applied to all dogs. But the clinical lesson the authors highlight is worth knowing: if a dog experiences recurrent infections, especially in more than one body system, an immune disorder may be worth investigating.
Here are some signs that might prompt a conversation with your vet about immune testing:
- Infections that keep coming back after treatment, especially pneumonia or skin infections
- Gut problems that don’t fully resolve — chronic diarrhea, vomiting, or poor response to standard gut treatments
- Infections in multiple locations at the same time or in close succession
- Poor response to antibiotics or infections caused by unusual or resistant bacteria
Immune testing in dogs is not routine for every sick pet. But in cases where the pattern doesn’t quite add up, it can make a real difference in understanding and managing the underlying problem.
Breeds and Genetic Background
Certain dog breeds are more prone to immune system differences than others. Poodles and their mixed-breed relatives (like Bernedoodles, Goldendoodles, and Labradoodles) have been noted in veterinary literature as having a somewhat higher incidence of immune-related conditions, though selective IgA deficiency can occur in many breeds. If you have a dog from a breed known for immune sensitivity, keeping that in mind during health conversations with your vet can be helpful — though it shouldn’t cause alarm without clinical signs.
How Vets Diagnose IgA Deficiency
Diagnosing selective IgA deficiency requires a blood test to measure immunoglobulin levels. It’s not part of a standard wellness panel, so it typically needs to be specifically requested or ordered when the clinical picture suggests it. The test compares your dog’s IgA level to a normal reference range for dogs. A significantly low reading — especially combined with a history of recurrent mucosal infections (lung, gut, or both) — can point toward a diagnosis.
There’s no cure for selective IgA deficiency in dogs, but knowing about it changes how infections are managed. Vets can be more proactive about monitoring, choose treatments more carefully, and counsel owners on what signs to watch for so problems are caught early.
A Takeaway for Any Dog With Recurring Problems
The main value of this case report is the pattern it highlights. One infection is something that happens to many dogs. Two infections in different body systems that keep coming back despite treatment? That’s a signal worth following.
If your dog fits that pattern — recurrent respiratory infections, ongoing gut issues, or infections that resist standard treatment — ask your veterinarian whether an immune evaluation makes sense. A simple blood test to check immunoglobulin levels could provide answers that make a real difference in your dog’s long-term care.
This research is based on a single dog, and larger studies would be needed to understand how often selective IgA deficiency drives this pattern in the wider dog population. But for this one Bernedoodle, identifying the underlying immune gap changed everything about how the case was managed.
This article summarizes peer-reviewed research for educational purposes. Always consult with your veterinarian for personalized advice about your pet’s health and behavior.