Heavy metal, abdominal pain in a dog

Unless you’re unlucky enough to live downwind of a mining operation, lead poisoning is a disease on the decline. Urban vets still intermittently see patients with the characteristic neurological symptoms, after home renovations liberate lead paint dust for pet to ingest.  Rarely it may be the old car battery, discarded in a paddock, or pewter drinking bowl. This toxic metal can also impact of  the health of human family members and vets may need to liaise with their medico counterparts. Below is a case report of a stubborn case of lead poisoning with an unusual presentation.

.

.

History:

Lita, a 3 year-old, desexed, female Border collie, presented with a 1 week history of mild lethargy, now associated with restlessness, agitated behaviour, and straining to defecate.  Apart from skin allergies and occasional episodes of constipation, there were no significant preexisting medical conditions. Physical exam identified only mild abdominal pain, and Xrays revealed large amounts of faeces in the colon. A tentative diagnosis of constipation was made and Lita was discharged that afternoon, after an enema, to be treated at home with a faecal softener.

Late that evening ‘Lita’ represented with increased agitation, dry, congested gums, severe abdominal pain and a temperature of 39.5°C. An elevated temperature could have been pain, or more serious diseases like obstructed or perforating bowel, especially given her colonic irrigation early that day. Intravenous fluids, with antibiotic, were commenced and blood samples taken for haematology and biochemistry. Three hours later, after abdominal pain persisted, despite narcotic pain relief,  emergency exploratory abdominal surgery was performed.

Surgery:

During surgery there appeared to be severe small intestinal spasm, gas distension of bowel and bone fragments in the colon, but nothing severe enough to explain the severe pain Lita seemed to be experiencing.  Bowel biopsies were collected, and Lita assessed as suffering severe intestinal spasm, of unknown cause, with secondary shock. Post-operatively, analgesia was maintained and over the following two days ‘Lita’ continued to improve with supportive therapy of intravenous fluids and antibiotic alone. The fever resolved and she began eating well.

Lab results:

Laboratory results revealed only mild elevation of liver enzymes and a marked elevation in red blood cells with nuclei, usually lost before they enter circulation, and a possible indicator of lead poisoning. Biopsies identified: acute erosive enteritis (bacterial and/or coronaviral in origin); severe chronic active eosinophilic enteritis; and enteric Sarcocystis infection. Most commonly, dogs with lead poisoning present with full, grand-mal siezures,  but this toxin can also result in more subtle behavioural or gastrointestinal symptoms.  A blood lead test was requested, and the owner was questioned regarding possible lead exposure.

Blood lead concentration was 5.3 pmol/L (> 1.7 considered toxic by the laboratory involved). Three possible sources of exposure were identified around the north shore, Sydney home. Previous owners of the property had repaired their trucks in the yard, over 20 years earlier; the house was sandblasted of it’s presumably lead based paint, 17 years previously; and the dog often slept under an old wooden boat. Enquires confirmed nautical anti-fouling agents contained mercury rather than lead.

Therapy:

Chelation therapy, which binds with the lead and carries it into the urine, was administered as subcutaneous injections twice daily for 5 days, followed by twice weekly for 4 weeks. Two weeks subsequently, repeat blood lead level was still in the toxic range (1.8 pmol/L) and the twice weekly treatment regimen was repeated for a further 4 weeks. Another blood sample was then submitted 2 weeks after discontinuation of therapy. Blood lead was 1.5 pmol/L, considered to be in the ‘suspect’ range (0.7 to 1.7 pmol/L).

Discussions with experts raised the possibility of lead continuing to leach from the bones and soft tissue compartments, maintaining blood lead concentrations without ongoing environmental exposure to the toxin. However, no one could provide any indication of the period over which this effect can occur.

It was decided to repeat the blood assay after 6 weeks without treatment. This test revealed blood lead was in the toxic range once again (2.3 pmol/L), and the twice weekly regimen of injections, described above,  was repeated. Finally, after 3 cycles of chelation therapy, Lita’s blood lead fell within the ‘normal range’.

Yes, there is a Blood lead level deemed to be normal! It simply implies a level that has not been proven to have a toxic effect, as far as we know. Like Mercury and Cadmium, we only just beginning to glimpse the long term and broad ranging toxic effects these metals can have.

Forensic toxicology:

Three months later the owner, now very familiar with the clinical signs of lead intoxication, accurately diagnosed the cause of recurrent neurological signs of agitation and pacing. Blood lead was again elevated. Chelation therapy was recommenced, and the NSW Lead Group and environmental toxicology consultants were contacted. Soil samples for lead assay were collected in the yard.

An analytical laboratory examined four samples, three adjacent the house and one 20m further away in the yard. The results were 35400, 28400, 3630, and 2050 mg/kg respectively, (normal range 200 to 300 mg/kg), The area were ‘Lita’ frequently lay was 3.5% lead!

As lead is not absorbed through the skin, Lita’s allergies, and associated licking and chewing of her itchy skin, may have increase her oral lead intake. The distribution of lead in the yard suggested the source was paint sand blasted from walls of the house. Interestingly, the owner recalled clouds of paint dust billowing across the fence provoking complaints from a school nearby.

Public health:

Young children are most vulnerable to the effects of lead ingestion due to mouthing activity,  and the severe impact it can have on intellectual development. However, inhalational intoxication occurs in adults exposed to aerosolised paint dust. Recent headline lead poisoning cases seem to happen on a mass scale: the indigenous communities of Mt Isa, downwind of mining operations; and the flock deaths of native birds in the mining port of Esperance.

In Lita’s case, there was little likelihood of ongoing lead exposure in other family members, the teenage kids who grew up Lita’s yard were performing well at school, and human testing were not conducted.  Vets sometimes need to consider the broader public health risk associated with environmental lead and  ensure clients are referred to medical practitioners when appropriate.

Lead poisoning  is one of the more elusive diagnoses when a dog presents with acute abdominal pain, without overt neurological signs.  Due to long-term persistence of lead residues, recent historical events may not always provide clues to with diagnosis of the disease, or pinpoint the source. Easily identifiable sources of lead can be simply and expediently removed from the environment, while cryptic  contamination is more likely to result in repeated intoxications.

‘Lita’ responded well to her final series of injections and, following excavations, is now lounging comfortably on a luxurious bed of freshly laid turf.

Tags: , , , , , , , , , ,

One Response to “Heavy metal, abdominal pain in a dog”

  1. japanese detox foot pads says:

    I have examined your excellent article, your site is pleasing to the eye. Thank you for putting yourself out there. I invite your advice on my own site that features posts on health related issues including and especially detox foot patch and their effeciveness as told by posters.

Leave a Reply